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1

TWO-PHASE FLOW OF TWO HFC REFRIGERANT MIXTURES THROUGH SHORT-TUBE ORIFICES  

EPA Science Inventory

The report gives results of an experimental investigation to develop an acceptable flow model for short tube orifice expansion devices used in heat pumps. The refrigerants investigated were two hydrofluorocarbon (HFC) mixtures considered hydrochlorofluorocarbon (HCFC)-22 replacem...

2

The Performance Evaluation of Vapor Compression Heat Pump System Using HFC Alternative Refrigerant Mixtures  

NASA Astrophysics Data System (ADS)

This paper deals with an experimental study on the performance evaluation of heat pump systems using HFC alternative refrigerants. The tested heat pump systems are modified from the R22 use to alternative refrigerants. Refrigerant mixtures of R410A, R407C. R32/125 and R32/134a are tested. where R410A and R407C launched into global market recently. Pure refrigerants of R22, R32, R125 and R134a are also tested. The experimental results of alternative refrigerants are evaluated in comparison with the result of R22, and the following are confirmed : (1) the performance of R32 is the highest. (2) adding R125 to R32 and R32/134a results into the deterioration of the performance, (3) the use of counter flow-like heat exchangers for a zeotropic refrigerant mixtures are effective, and (4) in case of R410A. the modification of the compressor to fit operating pressure heightens the performance. The effects of the performance of components on the COP are also analyzed based on the measured thermodynamic states at both ends of components in the system. Then, it is clarified that the most effective factor is irreversibility of compressors and the following is the pressure drop in low pressure side including the evaporator and the suction pipe.

Taira, Shigeharu; Yazima, Ryuzaburo; Tarutani, Isamu; Koyama, Shigeru

3

An Assessment of Thermodynamic Models for HFC Refrigerant Mixtures Through the Critical-Point Calculation  

NASA Astrophysics Data System (ADS)

An assessment of thermodynamic models for HFC refrigerant mixtures based on Helmholtz energy equations of state was made through critical-point calculations for ternary and quaternary mixtures. The calculations were performed using critical-point criteria expressed in terms of the Helmholtz free energy. For three ternary mixtures: difluoromethane (R-32) + pentafluoroethane (R-125) + 1,1,1,2-tetrafluoroethane (R-134a), R-125 + R-134a + 1,1,1-trifluoroethane (R-143a), and carbon dioxide (CO2) + R-32 + R-134a, and one quaternary mixture, R-32 + R-125 + R-134a + R-143a, calculated critical points were compared with experimental values, and the capability of the mixture models for representing the critical behavior was discussed.

Akasaka, Ryo

2008-08-01

4

Heat transfer and pressure drop characteristics of HFC quaternary refrigerant mixtures inside horizontal enhanced surface tubing  

Microsoft Academic Search

Heat transfer characteristics of two-phase flow condensation and boiling of quaternary (four components) refrigerant mixtures, on air\\/refrigerant horizontal enhanced surface tubing are presented, discussed and compared to other refrigerants proposed as substitutes for CFC-502, such as R-507 and R-407B. Heat transfer characteristics, such as average heat transfer coefficients, as well as pressure drops of ternary azeotropic refrigerant mixtures, flow condensation

S. M. Sami; B. Song

1996-01-01

5

Pressure drop of pure hfc refrigerants and their mixtures flowing in capillary tubes  

Microsoft Academic Search

The pressure drop of a capillary tube flow is experimentally investigated. In this study, pure refrigerants such as R32, R125 and R134a and their mixtures such as R32\\/R134a (3070 by mass fraction), R32\\/R125 (6040), R125\\/R134a (3070) and R32\\/R125\\/R134a (23\\/25\\/52) are used as test fluids. The binary interaction parameters for viscosities of the liquid state of refrigerant mixtures are found based

S.-D. Chang; S. T. Ro

1996-01-01

6

HFC Supermarket Refrigeration Demonstration. Phases 1 and 2.  

National Technical Information Service (NTIS)

The HFC Supermarket Refrigeration Demonstration tested and evaluated HFC refrigerants in a new Shop 'n Save supermarket in Glens Falls, New York. This project included laboratory testing of HFC refrigerants for medium- and low-temperature application, the...

H. Borhanian L. Rafuse

1996-01-01

7

Novel refrigeration lubricants for use with HFC refrigerants  

Microsoft Academic Search

A series of fluorinated alkyl aryl ethers composed of hydrocarbon components, fluorinated alkyl groups and ether linkage groups were evaluated as refrigeration lubricants for use with hydrofluorocarbon (HFC) refrigerants. The novel structure of these lubricants eliminates the problems of poor stability and high moisture absorption that are associated with conventional refrigeration lubricants for use with HFC refrigerants, such as polyalkylene

Hiroyuki Fukui; Ken-ichi Sanechika; Masanori Ikeda

2000-01-01

8

HFC supermarket refrigeration demonstration. Phases 1 and 2  

Microsoft Academic Search

The HFC Supermarket Refrigeration Demonstration tested and evaluated HFC refrigerants in a new Shop `n Save supermarket in Glens Falls, New York. This project included laboratory testing of HFC refrigerants for medium- and low-temperature application, the design of a supermarket refrigeration system to accommodate the new refrigerants, installation, start-up, and field monitoring.

H. Borhanian; L. Rafuse

1996-01-01

9

HFC supermarket refrigeration demonstration. Phases 1 and 2  

SciTech Connect

The HFC Supermarket Refrigeration Demonstration tested and evaluated HFC refrigerants in a new Shop `n Save supermarket in Glens Falls, New York. This project included laboratory testing of HFC refrigerants for medium- and low-temperature application, the design of a supermarket refrigeration system to accommodate the new refrigerants, installation, start-up, and field monitoring.

Borhanian, H.; Rafuse, L.

1996-04-01

10

Viscosities of HFC-32 and HFC-32/lubricant mixtures  

SciTech Connect

A modified capillary tube method has been used to measure viscosities for HFC-32 over a temperature range from {minus}20 to 90{degrees}C and a pressure range from 0.1 to 5.3 MPa, and for the liquid mixtures of HFC-32 with a synthetic polyolester oil at temperatures from 20 to 75{degrees}C and oil mass fractions from 0.44 to 1. Estimated uncertainties in the measured viscosities do not exceed {plus_minus}1.2 and {plus_minus}1.8% for the pure fluorocarbon and the mixtures, respectively. It is found that viscosity isotherms for HFC-32 at subcritical temperatures exhibit a minimum with increasing pressure, with the viscosity decreasing as much as 10% relative to its value at one atmosphere. Correlations are presented for dilute gas viscosities, excess viscosities, and saturated liquid and vapor viscosities. These correlations are shown to fit this data within experimental uncertainties. For HFC-32/lubricant mixtures, a free-volume viscosity model has been applied to correlate the experimental data.

Geller, V.Z. [Thermophysics Research Center, San Francisco, CA (United States); Paulaitis, M.E. [Univ. of Delaware, Newark, DE (United States); Bivens, D.B. [E.I. du Pont Nemours and Co., Wilmington, DE (United States)

1996-01-01

11

Ozone friendly HFC134a\\/HC mixture compatible with mineral oil in refrigeration system improves energy efficiency of a walk in cooler  

Microsoft Academic Search

In the event of chlorofluorocarbon (CFC) phase out, identifying a long term alternative to meet all our requirements in respect of system performance and service is an important area for research in the refrigeration and air conditioning (RAC) sector. Even though HFC134a and the HC blend (containing 55.2% HC600a and 44.8% HC290) have been reported to be substitutes for CFC12,

S. Joseph Sekhar; K. Senthil Kumar; D. Mohan Lal

2004-01-01

12

Condensation heat transfer coefficients of binary HFC mixtures on low fin and Turbo-C tubes  

Microsoft Academic Search

In this study, external condensation heat transfer coefficients (HTCs) are measured for nonazeotropic refrigerant mixtures (NARMs) of HFC32\\/HFC134a and HFC134a\\/HCFC123 on a low fin and Turbo-C tubes. All measurements are taken at the vapor temperature of 39°C with the wall subcooling of 3–8°C. Test results showed that condensation HTCs of NARMs on enhanced tubes were severely degraded from the ideal

Dongsoo Jung; Soonam Chae; Dongsoo Bae; Gilsang Yoo

2005-01-01

13

Effects of CFC and HFC refrigerants and ester lubricants on polyester insulation materials  

Microsoft Academic Search

Three polyester motor insulation films-“standard” poly ethylene terephthlate (PET), “low oligomer” PET, and poly ethylene naphthalate (PEN)-have been examined for compatibility with a range of ozone benign HFC refrigerants and mixed acid polyolester lubricants. The results indicate that the R134a\\/ester lubricant mixture is considerably more aggressive in terms of oligomer extraction than CFC 12\\/mineral oil standard refrigerant\\/lubricant mixtures. However, low

D. W. Anderson; M. Handa

1995-01-01

14

New concepts for refrigerant leak detection and mixture measurement  

NASA Astrophysics Data System (ADS)

Since the discovery that chlorofluorocarbons (CFC's) destroy the ozone layer, the need to reduce the release of these refrigerants into the environment has become critical. A total ban of ozone-depleting CFC's is expected within a few years, and hydrofluorocarbons (HFC's) and fluorocarbons (FC's) and their mixtures are expected to be used during a transition period. Several HFC and FC refrigerants are currently being considered as CFC substitutes. The electronic refrigerant leak detectors currently being considered as CFC substitutes. The electronic refrigerant leak detectors currently on the market were developed to detect CFC's and are not as sensitive to HFC's. Although incremental improvement can be made to these devices to detect HFC's, they often lead to increased false signals. Also, there is no simple device available to measure the composition of a refrigerant mixture. The authors present two new concepts to aid in the development of two portable instruments that can be used for HFC leak detection and for quantitative measurement of refrigerant mixture compositions. The development of simple, easy-to-use portable leak detectors and refrigerant mixture meters is essential to the wide use of alternative refrigerants in industry.

Chen, F. C.; Allman, S. L.; Chen, C. H.

15

PERFORMANCE OF CHLORINE-FREE BINARY ZEOTROPIC REFRIGERANT MIXTURES IN A HEAT PUMP  

EPA Science Inventory

The report gives results of a study that uses a simulation model and an experimental heat pump apparatus with counterflow heat exchangers to show that two hydrofluorocarbon (HFC) refrigerant mixtures, HFC-32/-152a and HFC-32/-134a, may be considered to be replacements for hydroch...

16

HFC-134A and HCFC-22 supermarket refrigeration demonstration and laboratory testing. Phase I. Final report  

SciTech Connect

Aspen Systems and a team of nineteen agencies and industry participants conducted a series of tests to determine the performance of HFC-134a, HCFC-22, and CFC-502 for supermarket application. This effort constitutes the first phase of a larger project aimed at carrying out both laboratory and demonstration tests of the most viable HFC refrigerants and the refrigerants they replace. The results of the Phase I effort are presented in the present report. The second phase of the project has also been completed. It centered on testing all viable HFC replacement refrigerants for CFC-502. These were HFC-507, HFC-404A, and HFC-407A. The latter results are published in the Phase II report for this project. As part of Phase I, a refrigeration rack utilizing a horizontal open drive screw compressor was constructed in our laboratory. This refrigeration rack is a duplicate of one we have installed in a supermarket in Clifton Park, NY.

NONE

1996-04-01

17

Lubrication of rolling element bearings with HFC–polyolester mixtures  

Microsoft Academic Search

Manufacturers of refrigeration and air-conditioning compressors have had to re-evaluate their knowledge of compressor bearing lubrication following the introduction of hydrofluorocarbon (HFC) refrigerants and polyolester lubricants. The lack of anti wear protection in comparison to traditionally used refrigerants\\/lubricants makes the lubrication of bearings using these modern systems a much more difficult task than before. This paper presents results from ongoing

Ulf J Jonsson

1999-01-01

18

Viscosity of gaseous mixtures of HFC125 (pentafluoroethane) + HFC134a (1,1,1,2-tetrafluoroethane) under pressure  

Microsoft Academic Search

This paper reports experimental results for the viscosity of gaseous mixtures of HFC-125 (pentafluoroethane) + HFC-134a (1,1,1,2-tetrafluoroethane) under pressure. The measurements were carried out with an oscillating-disk viscometer of the Maxwell type at temperatures from 298.15 to 423.15K. The viscosity was measured for three mixtures (mole fraction of HFC-125 is 0.7510, 0.5001 or 0.2508). The viscosity at normal pressure was

Chiaki Yokoyama; Tomomichi Nishino; Mitsuo Takahashi

2000-01-01

19

Heat transfer and pressure drop during HFC refrigerant vaporisation inside a brazed plate heat exchanger  

Microsoft Academic Search

This paper presents the experimental heat transfer coefficients and pressure drop measured during HFC refrigerant 134a, 410A and 236fa vaporisation inside a small brazed plate heat exchanger: the effects of heat flux, refrigerant mass flux, saturation temperature, outlet conditions and fluid properties are investigated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure

G. A. Longo; A. Gasparella

2007-01-01

20

Viscosity of Gaseous Mixtures of HFC134a (1,1,1,2-Tetrafluoroethane)+HFC32 (Difluoromethane)  

Microsoft Academic Search

This paper reports experimental results for the viscosity of gaseous mixtures of HFC-134a (1,1,1,2-tetrafluoroethane)+HFC-32 (difluoromethane). The measurements were carried out with an oscillating-disk viscometer of the Maxwell type at temperatures from 298.15 to 423.15 K. The viscosity was measured for three mixtures containing 25.00, 52.40, and 74.98 mole% HFC-134a in HFC-32. Experimental results for the viscosity at normal pressures show

C. Yokoyama; T. Nishino; M. Takahashi

2004-01-01

21

Simulation of vapor-compression refrigeration cycles using HFC134a and CFC12  

SciTech Connect

A performance comparison analysis of vapor-compression refrigeration systems using refrigerant HFC134a and CFC12 is presented. The analysis is based on computer simulation of actual cycles rather than the ideal cycles. The simulation models for HFC134a and CFC12 are developed on the basis of fluid properties and thermo-hydraulic characteristics obtained from available experimental data and/or correlations. Using the simulation model thus developed, system performance with HFC134a and CFC12 are examined. A comparison of the performance of HFC134a and CFC12 is presented using COP (and compressor power) as a criterion for the same cooling load. Results indicate that the COP for HFC134a is slightly (about 3%) lower than that for a CFC12 system. This means that the power requirement for a HFC134a system is slightly higher than that for CFC12 system for an identical cooling requirement. A comparison of these two systems from a thermodynamic point of view is also presented using exergy loss as a performance evaluation criterion. These results indicate that the HFC134a system is only slightly inferior to the CFC 12 systems due to a higher (about 3%) exergy loss with HFC134a.

Chen, Q. [Combustion Dynamics Ltd., Halifax, Nova Scotia (Canada)] [Combustion Dynamics Ltd., Halifax, Nova Scotia (Canada); Prasad, R.C. [Univ. of New Brunswick, Saint John, New Brunswick (Canada). Dept. of Engineering] [Univ. of New Brunswick, Saint John, New Brunswick (Canada). Dept. of Engineering

1999-05-01

22

Ideal-Gas Heat Capacities and Virial Coefficients of HFC Refrigerants  

Microsoft Academic Search

Thermodynamic properties of HFC (hydrofluorocarbon) compounds have been extensively studied with worldwide interest as alternative refrigerants. Both quality and quantity in the experimental data far exceed those for the CFC and HCFC refrigerants. These data now provide a great opportunity to examine the validity of theoretical models, and vice versa. Among them, the ideal-gas heat capacity Cp0 and virial coefficients

A. Yokozeki; H. Sato; K. Watanabe

1998-01-01

23

Exploring policy strategies for mitigating HFC emissions from refrigeration and air conditioning  

Microsoft Academic Search

The growing demand for cooling throughout the world, possibly increased by global climate change, requires the implementation of policies to mitigate the related greenhouse gas (GHG) emissions from energy and refrigerant use in the refrigeration and air conditioning (RAC) sector. This article aims to contribute to the discussion on strategies to reduce HFC emissions from RAC by looking at their

M. Hekkenberg; Anton J. M. Schoot Uiterkamp

2007-01-01

24

Solubility of HFC-134a refrigerant in glycol-type compounds: Effects of glycol structure. [1,1,1,2-tetrafluoroethane  

SciTech Connect

Environmental concerns have dictated the replacement of CFC-12 refrigerant with HFC-134a in air-conditioning (A/C) systems. Since polyglycols are synthetic compounds compatible with HFC-134a and considered as lubricants for the A/C compressor, interactions of HFC-134a with glycol-type compounds and thermodynamic properties of the solutions are important in designing an A/C system. In this work, the solubility of HFC-134a in four glycol-type compounds was measured at [minus]5 to 80 C and 90 to 960 kPa. HFC-134a had the greatest solubility in tetraethylene glycol dimethyl ether. HFC-134a was less soluble in hexylene glycol and tetraethylene glycol and least soluble in triethylene glycol. Mixtures of HFC-134a with TRIG or TGDE showed phase separation. Solubility data were used to calculate the activity coefficient of HFC-134a in glycol solutions. An equation of the form, ln[gamma][sub r] = (1 [minus] x[sub r])[A + Bx[sub r

Tseregounis, S.I.; Riley, M.J. (General Motors Research and Development Center, Warren, MI (United States). Fuels and Lubricants Dept.)

1994-04-01

25

HFC134a refrigerant gas hydrate formation process and RIN model  

Microsoft Academic Search

In this paper, the macroscopic visualization experiments of HFC-134a refrigerant gas hydrate formation are investigated. According\\u000a to the macroscopic photos and Mori’s microscopic photos of HFC-134a hydrate formation process, the mechanism of gas hydrate\\u000a formation is analyzed. A random inducement nucleation model is presented to describe the hydrate formation process. The factors\\u000a affecting the fractal growth dimension in the model,

Yongli Zhao; Kaihua Guo; Xiaocong Liu; Shuanshi Fan; Bifen Shu; Xinshi Ge

2001-01-01

26

Pressure drop of HFC refrigerants inside evaporator and condenser coils as determined by CFD  

Microsoft Academic Search

This paper presents pressure-drop data for inside evaporator and condenser coils of refrigeration and air conditioning systems using hydrofluorocarbon (HFC) refrigerants and blends. Computational fluid dynamics (CFD) was used to simulate the two-phase flows of different refrigerants through two types of coil common to the evaporator and condenser components found in a typical vapour-compression system. A comparison of single-phase and

S. J. Smith; L. Shao; S. B. Riffat

2001-01-01

27

Determination of properties of PVE lubricants with HFC refrigerants[PolyVinylEther  

SciTech Connect

Polyalkyleneglycol (PAG) and polyol ester (POE) have been developed as refrigeration lubricants, used with HFC134a. PAG is used for automotive air conditioning systems and POE is used for domestic reciprocating refrigerators and for A/C systems. Although PAG exhibits good lubricity performance, it is difficult to use for domestic reciprocating refrigerators due to its low dielectric property. POE is difficult to use for automotive A/C systems, due to hydrolysis and poor lubricity performance. Polyvinylether (PVE) can be used in place of PAG and POE with HFC refrigerants. PVE is used for A/C systems as well as refrigerator and freezer applications. PVE is an ideal lubricant for use with HFCs.

Kaneko, Masato; Sakanoue, Shuichi; Tazaki, Toshihiro; Tominaga, Shoichi; Takagi, Minoru; Goodin, M.

1999-07-01

28

Performance studies on mechanical + adsorption hybrid compression refrigeration cycles with HFC 134a  

Microsoft Academic Search

This paper presents the results of an investigation on the efficacy of hybrid compression process for refrigerant HFC 134a in cooling applications. The conventional mechanical compression is supplemented by thermal compression using a string of adsorption compressors. Activated carbon is the adsorbent for the thermal compression segment. The alternatives of bottoming either mechanical or thermal compression stages are investigated. It

N. D. Banker; P. Dutta; M. Prasad; K. Srinivasan

2008-01-01

29

Ideal-gas heat capacities and virial coefficients of HFC refrigerants  

SciTech Connect

Thermodynamic properties of HFC (hydrofluorocarbon) compounds have been extensively studied with worldwide interest as alternative refrigerants. Both quality and quantity in the experimental data far exceed those for the CFC and HCFC refrigerants. These data now provide a great opportunity to examine the validity of theoretical models, and vice versa. Among them, the ideal-gas heat capacity (C{sub p}{sup 0}) and virial coefficients derived from the experimental data are of particular interest, since they are directly related to the intramolecular and intermolecular potentials through the statistical mechanical procedure. There have been some discrepancies reported in the observed and theoretical C{sub p}{sup 0} for HFC compounds. The authors have performed new calculations for C{sub p}{sup 0} for several HFCs. The present results are consistent with the selected experimental values. The second (B) and Third (C) virial coefficients have been reported for these HFC refrigerants from speed of sound data and Burnett PVT data. Often, a square well-type intermolecular potential is employed to correlate the data. However, the model potential cannot account consistently for both B and C coefficients with the same potential parameters. They have analyzed the data with the Stockmayer potential and obtained self-consistent results for various HFC (R-23, R-32, R-125, R-134a, R-143a, and R-152a) compounds with physically reasonable potential parameters.

Yokozeki, A.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan)] [Keio Univ., Yokohama (Japan)

1998-01-01

30

Releases of refrigerant gases (CFC-12, HCFC-22 and HFC-134a) to the atmosphere  

NASA Astrophysics Data System (ADS)

Two of the gases, CFC-12 (dichlorodifluoromethane, CF 2Cl 2) and HCFC-22 (chlorodifluoromethane, CHClF 2) have long histories of emission from refrigeration and other uses. Production and sales records show the expected fall in the amounts of CFC-12 used in refrigeration after the Montreal Protocol came into effect but this does not seem to have been accompanied by significant substitution by HCFC-22, demand for which appears governed by organic growth. HFC-134a (1,1,1,2-tetrafluoroethane, CH 2FCF 3) is a relative newcomer that has partially substituted for CFC-12. After developing a single data set for the global use of each substance in refrigeration, foam blowing and aerosol propulsion, and other promptly emissive uses, annual releases of the compounds were estimated by applying emission functions derived from surveying both the producers of the chemicals and the principal industrial users. For CFC-12 and HFC-134a, atmospheric concentrations calculated from the emissions estimated here are in good agreement with observations, verifying that the emission functions adequately describe the relationship between the quantities in use, the atmospheric lifetimes of 100 and 14.6 years, respectively, and the extent of release into the atmosphere. The agreement between observation and calculation is poorer for HCFC-22, if its atmospheric lifetime is 12 years, but becomes much closer with a lifetime of 10 years. An 80% reduction in CFC requirement has been substituted only to the extent of 25% by HFC-134a. This is consistent with improved technology to curtail leakage and so enable lower system charges that, in turn, translate into less demand. For the same reason, the refrigeration emission function for HFC-134a over the period 1990-2000 was not significantly different from that of CFC-12. The lower absolute rate of leakage and lower absolute charge sizes combining to maintain a similar relative rate of loss.

McCulloch, Archie; Midgley, Pauline M.; Ashford, Paul

31

A review of lubrication and preformance issues in refrigeration systems using an HFC (R-134a) refrigerant  

SciTech Connect

It has been considered critical for refrigerant and compressor lubricant to be miscible with each other over part of the range of operating conditions of refrigerant systems. Adequate miscibility, many believe, provides oil return to the compressor. Presently, synthetic polyol esters have been selected for use with HFC refrigerants, such as R-134a, which are considered appropriate alternatives to CFCs. The authors will review the mechanical issues in miscible vs non-miscible naphthenic hydrocarbon oil-based lubricants. Extensive lab, test stand and cabinet testing has been conducted and data will be presented which show responsible and predictable performance based on the chemical and physical properties of the lubricant and refrigerant. Many non-miscible systems show satisfactory performance with the proper selection of lubricant, additives and mechanical configuration. 3 refs., 3 figs., 5 tabs.

Reyes-Gavilan, J.; Eckard, A.; Flak, T.; Tritak, T. [Witco Corporation, Oakland, NJ (United States)

1996-04-01

32

Evaluation of ozone-friendly hydrofluoropropane-based zeotropic refrigerant mixtures in a Lorenz-Meutzner refrigerator/freezer  

SciTech Connect

In this study, the L-M R/F having two evaporators and two intercoolers was experimentally tested in an environmental chamber according to Association of Home Appliance Manufacturers/Department of Energy testing standards using several hydrofluoropropane-based zeotropic mixtures. The results are compared to baseline testing with HFC-134a. A refrigerant sampling loop was added to determine the running composition of the mixture and its effect on the R/F performance.

Baskin, E.; Bayoglu, E.; Delafield, F.R.

1995-01-01

33

Study on the Interaction Coefficients in PR Equation with vdW Mixing Rules for HFC and HC Binary Mixtures  

NASA Astrophysics Data System (ADS)

The Peng-Robinson equation of state with the van der Waals mixing rules was used to correlate vapor-liquid equilibrium (VLE) data for HFC/HC, HFC/HFC, and HC/HC binary mixtures. The interaction parameter k ij was obtained for every binary mixture. It was assumed that k ij has contributions from the two components, and each component has its own constant contribution factor k i for the mixture, and the values of k ij indicate the degree in difference of properties between the two components. Therefore, the interaction parameters k ij is proposed as: k ij = k i - k j . The values of the mixing factor k i for Hydrofluorocarbons (HFCs) and Hydrocarbons (HCs), including propane, isobutane, n-butane, R23, R32, R125, R143a, R134a, R152a, R227ea R236fa, R236ea, and R245fa, were obtained by least-square fitting. In total, 39 refrigerant binary mixtures were analyzed on the basis of this method, and the results showed good agreement with experimental data. The overall average absolute deviations of pressure and vapor mole fraction are 1.3 % and 0.0089, respectively.

Chen, Jian-Xin; Hu, Peng; Chen, Ze-Shao

2008-12-01

34

Performance investigation on new refrigerant mixture  

Microsoft Academic Search

this research presents a theoretical investigation on the performance of a vapour compression refrigerating system using different mixtures of Hydrocarbons and Hydrofluorocarbons refrigerants as a refrigerant. Genetic Algorithm method was used to solve a nonlinear constrained optimization problem for the selection of the best blend. The performance of new mixtures of Hydrocarbons and Hydrofluorocarbons refrigerants is compared with the performance

E. Khorshid; B. Alshriaan; A. Alsairafi; A. Alazemi; A. Alhaddad

2011-01-01

35

Miscibility comparison for three refrigerant mixtures and four component refrigerants  

SciTech Connect

Miscibility data were taken and compared for seven different refrigerants when mixed with the same polyol ester (POE) lubricant. Four of the seven refrigerants were single-component refrigerants while three of the refrigerants were mixtures composed of various combinations of the pure refrigerants. The purpose of this research was to investigate the difference in miscibility characteristics between refrigerant mixtures and their respective component refrigerants. The POE lubricant was a penta erythritol mixed-acid type POE which has a viscosity ISO32. The four pure refrigerants were R-32, R-125, R-134a, and R-143a and the three refrigerant mixtures were R-404A, R407C, and R-410A. The miscibility tests were performed in a test facility consisting of a series of miniature test cells submerged in a constant temperature bath. The test cells were constructed to allow for complete visibility of the refrigerant/lubricant mixtures under all test conditions. The tests were performed over a concentration range of 0 to 100% and a temperature range of {minus}40 to 194 F. The miscibility test results for refrigerant mixtures are compared to component refrigerants. In all cases, the refrigerant mixtures appear to have better miscibility than their most immiscible pure component.

Kang, H.M.; Pate, M.B.

1999-07-01

36

High pressure vapor-liquid equilibria of binary mixtures composed of HFC32, 125, 134a, 143a, 152a, 227ea and R600a (isobutane)  

Microsoft Academic Search

The vapor–liquid equilibrium data for six binary mixtures of isobutane+HFC-32, +HFC-125, +HFC-134a, +HFC-143a, +HFC-152a, and +HFC-227ea were correlated with the Peng–Robinson–Stryjek–Vera (PRSV) EOS combined with the NRTL excess free energy model and original Huron–Vidal (HVO) mixing rules. Almost all the calculated values with these models give good agreement with the experimental data. In addition, the nonideality of these binary mixtures

Ji Young Park; Jong Sung Lim; Byung Gwon Lee

2002-01-01

37

Heat capacities and Joule-Thomson coefficients of HFC refrigerants  

SciTech Connect

In this report, the authors have examined the behavior of heat capacities and Joule-Thomson coefficients in low- and moderate-density regions based on recent theoretical studies of the ideal-gas heat capacity and virial coefficients of R-32, R-125, R-134a, r-143a, and R-152a. The results have been compared with those derived from empirical equations of state which have been recently developed, based on a large quantity of experimental data for these refrigerants. Both results are in good agreement. Proper behaviors for these second-derivative properties justify the use of the empirical equations of state in low-temperature and low-density regions where no experimental data are available.

Yokozeki, A.; Sato, H.; Watanabe, K. [Keio Univ., Yokohama (Japan). Dept. of System Design Engineering] [Keio Univ., Yokohama (Japan). Dept. of System Design Engineering

1999-01-01

38

Heat pumps and refrigerating units using a non-chlorinated refrigerant (HFC 134A).  

National Technical Information Service (NTIS)

The most often mentioned candidate named as the safe replacement to the most common of the ozone-attaching CFCs (CFC 12) is HFC 134a. It has thermodynamic and physical characteristics similar to those of CFC 12. Traditional lubricants are non-miscible wit...

B. Hivet R. Aufils L. Vuillame

1992-01-01

39

EVALUATION OF PERFORMANCE AND COMPOSITION SHIFT OF ZEOTROPIC MIXTURES IN A LORENZ-MEUTZNER REFRIGERATOR/FREEZER  

EPA Science Inventory

Results from previous testing of this refrigerator/freezer (R/F) using a 750 Btu/hr compressor and several zeotrophic mixtures revealed a performance enhancement up to 16 percent above that of HFC-134a. In the study presented in this paper, the Lorenz-Meutzner (LM) R/F equipped ...

40

Phase equilibria of chlorofluorocarbon alternative refrigerant mixtures  

SciTech Connect

Isothermal vapor-liquid equilibrium data were determined for binary systems of difluoromethane/1,1,1,2-tetrafluoroethane (HFC-32/HFC-134a), difluoromethane/pentafluoroethane (HFC-32/HFC-125), difluoromethane/1,1,1-trifluoroethane (HFC-32/HFC-143A), and difluoromethane/1,1-difluoroethane (HFC-32/HFC-152a). The vapor and liquid compositions and pressures were measured in a circulation-type apparatus at 303.15 K and 323.15 K. The experimental data were compared with literature results and correlated with the Canahan-Starling-De Santis equation of state within the uncertainty of {+-}1.0%.

Lee, B.G.; Park, J.Y.; Lim, J.S.; Cho, S.Y.; Park, K.Y. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of)] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of)

1999-03-01

41

Chemical and thermal stability of refrigerant-lubricant mixtures with metals  

SciTech Connect

This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.

Huttenlocher, D.F.

1992-07-10

42

Modeling and design study using HFC-236ea as an alternative refrigerant in a centrifugal compressor. Final report, January 1994-September 1995  

SciTech Connect

The Environmental Protection Agency (EPA) in cooperation with the Navy has been seeking a CFC-114 drop-in placement. One alternative HFC refrigerant which appears to satisfy all physical and chemical characteristics for the Navy fleet was found to be HFC-236ea refrigerant. The project represents a part of the investigation directed to evaluate this CFC-114 alternative refrigerant as a possible drop-in replacement in Navy chillers. The objective of the study was to conduct a thorough literature review regarding centrifugal compressors and the, on the basis of the information gathered, build an accurate but simple compressor model utilizing the available compressor experimental data. Further, the developed compressor model would be used to suggest eventual design adjustments to enhance compressor performance with the alternative HFC-236ea refrigerant.

Popovic, P.; Shapiro, H.N.

1997-04-01

43

Nearly Azeotropic Mixtures To Replace Refrigerant 12  

NASA Technical Reports Server (NTRS)

Number of nearly azeotropic fluid mixtures have saturation pressures similar to Refrigerant 12 while being about 2 percent as damaging to ozone layer. Five mixtures of R134a, R152a, R124, and R142b have low boiling-point spreads, low toxicity, and low ozone-damaging capability, are nonflammable, and more compatible with conventional oils than R134a. Pressure of combinations nearly equal to R12, and mixtures may be good "drop-in substitutes". Overall composition not altered by leakage. Usable in commercial, automotive, and household refrigerators and air conditioners.

Jones, Jack A.

1992-01-01

44

Measurements of the Saturated Liquid Density for HFC-134a+Oil Mixtures  

NASA Astrophysics Data System (ADS)

The present paper reports experimental results of the saturated liquid density for four combinations of HFC-134a and its compatible lubricants such as Polyalkyleneglycol (PAG) and Polyolester (POE) oils. The saturated liquid density is measured by the method using spherical buoys made of glass. The experiments have been conducted for temperatures from 256 to 313 K, densities from 933 to 1327 kg• m-3 and oil-concentrations from 0 to 1. The present results show that the saturated liquid density for HFC-134a+oil mixtures decreases with increasing oil-concentration at a constant-temperature while showing slightly positive or negative deviations from the mass fraction average for the experimental temperatures we have concerned.

Sato, Tomoaki; Takaishi, Yoshinori; Oguchi, Kosei

45

Condensation of Downward-Flowing Zeotropic Mixture HCFC-123/HFC-134a on a Staggered Bundle of Horizontal Low-Finned Tubes  

NASA Astrophysics Data System (ADS)

Expenmentswere conducted to obtain row-by-row heat transfer data during condensation of downward-flowing zeotropic refrigerant mixture HCFC-123/HFC-134 a on a staggered bundle of horizontal low-finned tubes. The vapor temperature and the HFC-134a m ass fraction at the tube bundle inlet were maintained at about 50°C and 14% respectively. The refrigerant mass velocity ranged from 9 to 33 kg/m2s, and the condensation temperature difference from 2 to 12K. Four kinds of low-finned tubes with different fin geometry were tested. The highest heat transfer coefficient was obtained with a tube which showed the highest performance for HCFC-123. However, the effect of fin geometry was much smaller for the mixture than for HCFC-123. The heat transfer coefficient and the vapor-phase mass transfer coefficient decreased significantly with decreasing mass velocity. On the other hand, the mass transfer coefficient increased with condensation temperature difference. This was due to the effect of suction associated with condensation. On the basis of the analogy between heat and mass transfer, a dimensionless correlation of the mass transfer coefficient was developed for each tube.

Honda, Hiroshi; Takamatsu, Hiroshi; Takata, Nobuo

46

Performance of environmentally friendly CFC-12 replacements for refrigerator/freezers  

SciTech Connect

The paper presents the capacity and energy consumption of refrigerant replacements for HFC-134a and/or CFC-12 as determined by experimental testing and analysis. Refrigerator/freezer (R/F) tests were run according to the Association of Home Appliance Manufacturer`s testing conditions in an environmental test chamber. The charge was optimized for each refrigerant, and the results were compared to those for HFC-134a and CFC-12. The numerical model and experiment results were compared to verify the model. The paper investigates HFC-245cb/HFC-134 and HFC-134. Computer modeling predicts that these azeotropes will perform similarly to HFC-134a, which has a higher global warming potential than any of the mixtures except HFC-245cb/HFC-134.

Baskin, E.; Bayoglu, E.S.; Delafield, F.R.

1995-12-31

47

Chemical and thermal stability of refrigerant-lubricant mixtures with metals. Quarterly report, 1 April 1992--30 June 1992  

SciTech Connect

This report presents completed sealed tube stability test results for the following eight refrigerant/lubricant mixtures: R-22/mineral oil; R-124/alkylbenzene; R-134a/pentaerythritol (PE) ester (mixed acid); R- 134a/PE (branched acid); R-134a/ PE (100 cSt viscosity); R- 142b/alkylbenzene; R-143a/ PE (branched acid); R-152a/alkylbenzene. Partial results are shown for an additional eight refrigerant-lubricant mixtures. Though work is in progress, no data are available at this point in time for the five remaining test mixtures. Reported are: visual observations on aged sealed tubes, gas chromatographic analyses on the vapor phase contents of the tubes, chloride ion contents of HCFC containing mixtures or fluoride ion contents of HFC mixtures, and total acid number values and infrared analysis results for mixtures containing ester lubricants.

Huttenlocher, D.F.

1992-07-10

48

Estimated 2017 refrigerant emissions of 2,3,3,3-tetrafluoropropene (HFC-1234yf) in the United States resulting from automobile air conditioning.  

PubMed

In response to recent regulations and concern over climate change, the global automotive community is evaluating alternatives to the current refrigerant used in automobile air conditioning units, 1,1,1,2-tetrafluoroethane, HFC-134a. One potential alternative is 2,3,3,3-tetrafluoropropene (HFC-1234yf, also known as HFO-1234yf). We have developed a spatially and temporally resolved inventory of likely future HFC refrigerant emissions from the U.S. vehicle fleet in 2017, considering regular, irregular, servicing, and end-of-life leakages. We estimate the annual leak rate emissions for each leakage category for a projected 2017 U.S. vehicle fleet by state, and spatially apportion these leaks to a 36 km square grid over the continental United States. This projected inventory is a necessary first step in analyzing for potential atmospheric and ecosystem effects, such as ozone and trifluoroacetic acid production, that might result from widespread replacement of HFC-134a with HFC-1234yf. PMID:20000517

Papasavva, Stella; Luecken, Deborah J; Waterland, Robert L; Taddonio, Kristen N; Andersen, Stephen O

2009-12-15

49

GAS CHROMATOGRAPHIC RETENTION PARAMETERS DATABASE FOR REFRIGERANT MIXTURE COMPOSITION MANAGEMENT  

EPA Science Inventory

Composition management of mixed refrigerant systems is a challenging problem in the laboratory, manufacturing facilities, and large refrigeration machinery. Ths issue of composition management is especially critical for the maintenance of machinery that utilizes zeotropic mixture...

50

Chemical and thermal stability of refrigerant-lubricant mixture with metal  

SciTech Connect

This report presents completed sealed tube stability test results for the R-123/mineral oil mixture and preliminary results for seven of the eighteen contracted refrigerant-lubricant mixtures. The R-123 mixture was tested at 105, 150, and 175{degrees}C. The results obtained indicate that prolonged exposure to temperatures of about 150{degree}C and higher will lead to rapid chemical deterioration of the R-123/mineral oil system. Chlorotrifluoroethane (R-133a) and trifluoroethane (R-143a) have been identified as decomposition products of R-123. Testing at 150 and 175{degrees}C have been completed for the HCFC refrigerants R-22, R-124, and R-142b with either mineral oil or alkylbenzene lubricants. These mixtures were very stable at the indicated temperatures. Testing at a higher temperature level will be necessary to define their upper temperature limits. Similarily, partial test results are available for HFC refrigerants R-32, R-125, R-134a (two esters), and R-143a with pentaerythritol ester lubricants at the 150 and 175{degrees}C temperature levels. Again, all five mixtures were found to be extremely stable at the test temperatures and additional testing will be needed to establish their upper temperature limits.

Huttenlocher, D.F. (Spauschus Associates, Inc., Atlanta, GA (United States))

1992-03-31

51

Global warming from hfc  

Microsoft Academic Search

Using a variety of public sources, a computer model of hydrofluorocarbon (HFC) refrigerant emissions in the UK has been developed. This model has been used to estimate and project emissions in 2010 under three types of scenarios: (1) business as usual; (2) voluntary agreements to reduce refrigerant leakage; and (3) comprehensive regulations to reduce refrigerant leakage. This resulting forecast is

Eric Johnson

1998-01-01

52

Comparison of R-290 and two HFC blends for walk-in refrigeration systems  

Microsoft Academic Search

To help provide a clear understanding of the relative performance potential of HFCs (R-404A and R-410A) as compared to R-290 for walk-in refrigeration systems representing direct expansion commercial refrigeration systems with small charge, an experimental evaluation of the three refrigerants was investigated. To compare the environmental impact of refrigerants over the entire life cycle of fluid and equipment, including power

Yunho Hwang; Dae-Hyun Jin; Reinhard Radermacher

2007-01-01

53

Elastohydrodynamic Lubrication with Polyolester Lubricants and HFC Refrigerants, Final Report, Volume 1  

SciTech Connect

The objective of this study was to investigate the film formation properties of refrigeration lubricants using the ultrathin film elastohydrodynamic (EHD) interferometry technique and to study the effects of refrigerants on film formation. Film thickness measurements were conducted as a function of lubricant viscosity, speed, temperature, and refrigerant concentration. Based on the EHD film thickness data, effective pressure-viscosity coefficients were calculated for the test fluids at different temperatures and the effects of refrigerants on pressure-viscosity properties were investigated.

Gunsel, Selda; Pozebanchuk, Michael

1999-04-01

54

Experimental investigation on condensation heat transfer and pressure drop of new HFC refrigerants (R134a, R125, R32, R410A, R236ea) in a horizontal smooth tube  

Microsoft Academic Search

This paper reports experimental heat transfer coefficients and pressure drops measured during condensation inside a smooth tube when operating with pure HFC refrigerants (R134a, R125, R236ea, R32) and the nearly azeotropic HFC refrigerant blend R410A. Data taken when condensing HCFC-22 are also reported for reference. The experimental runs are carried out at a saturation temperature ranging between 30 and 50°C,

A. Cavallini; G. Censi; D. Del Col; L. Doretti; G. A. Longo; L. Rossetto

2001-01-01

55

Energy and global warming impacts of HFC refrigerants and emerging technologies: TEWI-III  

Microsoft Academic Search

The use of hydrofluorocarbons (BFCs) which were developed as alternative refrigerants and insulating foam blowing agents to replace chlorofluorocarbons (CFCs) is now being affected by scientific investigations of greenhouse warming and questions about the effects of refrigerants and blowing agents on global warming. A Total Equivalent Warming Impact (TEWI) assessment analyzes the environmental affects of these halogenated working fluids in

J. R. Sand; S. K. Fischer; V. D. Baxter

1997-01-01

56

REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures  

National Institute of Standards and Technology Data Gateway

SRD 73 NIST REFLEAK: NIST Leak/Recharge Simulation Program for Refrigerant Mixtures (PC database for purchase)   REFLEAK estimates composition changes of zeotropic mixtures in leak and recharge processes.

57

Releases of refrigerant gases (CFC12, HCFC22 and HFC134a) to the atmosphere  

Microsoft Academic Search

Two of the gases, CFC-12 (dichlorodifluoromethane, CF2Cl2) and HCFC-22 (chlorodifluoromethane, CHClF2) have long histories of emission from refrigeration and other uses. Production and sales records show the expected fall in the amounts of CFC-12 used in refrigeration after the Montreal Protocol came into effect but this does not seem to have been accompanied by significant substitution by HCFC-22, demand for

Archie McCulloch; Pauline M Midgley; Paul Ashford

2003-01-01

58

Two-phase heat transfer coefficients of three HFC refrigerants inside a horizontal smooth tube, part II: condensation  

Microsoft Academic Search

This paper presents local heat transfer results obtained during the condensation of Isceon 59, R407C and R404A in a smooth horizontal tube. The results have been compared with existing correlations for condensation heat transfer to assess the validity of these models for refrigerant mixtures. Two correlations (Dobson MK, Chato JC. Condensation in smooth horizontal tubes. Journal of Heat Transfer, Transactions

X. Boissieux; M. R. Heikal; R. A. Johns

2000-01-01

59

Energy and global warming impacts of HFC refrigerants and emerging technologies: TEWI-III  

SciTech Connect

The use of hydrofluorocarbons (BFCs) which were developed as alternative refrigerants and insulating foam blowing agents to replace chlorofluorocarbons (CFCs) is now being affected by scientific investigations of greenhouse warming and questions about the effects of refrigerants and blowing agents on global warming. A Total Equivalent Warming Impact (TEWI) assessment analyzes the environmental affects of these halogenated working fluids in energy consuming applications by combining a direct effect resulting from the inadvertent release of HFCs to the atmosphere with an indirect effect resulting from the combustion of fossil fuels needed to provide the energy to operate equipment using these compounds as working fluids. TEWI is a more balanced measure of environmental impact because it is not based solely on the global warming potential (GWP) of the working fluid. It also shows the environmental benefit of efficient technologies that result in less CO{sub 2} generation and eventual emission to the earth`s atmosphere. The goal of TEWI is to assess total global warming impact of all the gases released to the atmosphere, including CO{sub 2} emissions from energy conversion. Alternative chemicals and technologies have been proposed as substitutes for HFCs in the vapor-compression cycle for refrigeration and air conditioning and for polymer foams in appliance and building insulations which claim substantial environmental benefits. Among these alternatives are: (1) Hydrocarbon (HC) refrigerants and blowing agents which have zero ozone depleting potential and a negligible global warming potential, (2) CO{sub 2} as a refrigerant and blowing agent, (3) Ammonia (NH{sub 3}) vapor compression systems, (4) Absorption chiller and heat pumping cycles using ammonia/water or lithium bromide/water, and (5) Evacuated panel insulations. This paper summarizes major results and conclusions of the detailed final report on the TEWI-111 study.

Sand, J.R.; Fischer, S.K.; Baxter, V.D.

1997-06-01

60

Modified Peng-Robinson Equation of State for Pure and Mixture Refrigerants with R-32,R-125 and R-134a  

NASA Astrophysics Data System (ADS)

On the basis of critically-evaluated thermodynamic property data among those recently published, a new Peng-Robinson equation of state for the HFC refrigerants,R-32,R-125 and R-134a,has be end eveloped so as to represent the VLE properties in the vapor-liquid coexisting phase at temperatures 223K-323K. In accord with a challenge to correlate the binary and/or ternary interatction parameters as functions of temperature, we have also applied the present modified Peng-Robinson equation of state to the promising alternative HFC refrigerant mixtures, i.e., R-32/125,R-32/134a and R-32/125/134a systems. The developed equation of state improves significantly its effectiveness for practical engineering property calculations at refrigerantion and air-conditioning industries in comparison with conventional Peng-Robinson equation.

Ll, Jin; Sato, Haruki; Watanabe, Koichi

61

Vapor-liquid equilibrium, coexistence curve, and critical locus for binary HFC-32/HFC-134a mixture  

NASA Astrophysics Data System (ADS)

Two kinds of equilibrium measurements of binary R-32/134a mixtures were carried out. The vapor-liquid equilibria were measured by the static method in the temperature range between 283 and 313 K. On the basis of the present experimental data, the temperature dependence of the binary interaction parameter k 12 for two equations of state, namely, the Soave-Redlich-Kwong equation and Carnahan-Starling-De Santis equation, was discussed. The vapor-liquid coexistence curve near the critical point was also measured by the observation of meniscus disappearance. The critical temperatures and critical densities of 30 and 70 wt% R-32 mixtures were determined on the basis of the saturation densities along the coexistence curve in the critical region. In addition, a correlation of the critical locus for this mixture is proposed as a function of composition.

Higashi, Y.

1995-09-01

62

Two-phase heat transfer coefficients of three HFC refrigerants inside a horizontal smooth tube, part I: evaporation  

Microsoft Academic Search

This paper presents experimental heat transfer results obtained during the evaporation of Isceon 59, R407C and R404A in a horizontal tube. The results have been compared with existing correlations which characterise the evaporative heat transfer coefficient to assess the validity of these models for refrigerant mixtures. The results compared well with the (Gungor K.E., Winterton, R.H.S. Simplified general correlation for

X. Boissieux; M. R. Heikal; R. A. Johns

2000-01-01

63

Tubeside condensation of nonazeotropic refrigerant mixtures for two enhanced surfaces.  

National Technical Information Service (NTIS)

As part of the Building Equipment Research program at Oak Ridge National Laboratory (ORNL), nonazeotropic refrigerant mixtures (NARMs) are being investigated to replace chlorofluorocarbon compounds. The condensation of NARMs is not isothermal, and this ca...

J. C. Conklin E. A. Vineyard

1990-01-01

64

Tubeside evaporation of nonazeotropic refrigerant mixtures from two enhanced surfaces.  

National Technical Information Service (NTIS)

As part of the Building Equipment Research program at Oak Ridge National Laboratory, nonazeotropic refrigerant mixtures (NARMs) are being investigated to replace chlorofluorocarbon compounds. The evaporation of NARMs is not isothermal, and this can improv...

J. C. Conklin E. A. Vineyard

1990-01-01

65

Testing of propane\\/isobutane mixture in domestic refrigerators  

Microsoft Academic Search

The performance of a propane\\/isobutane (R290\\/R600a) mixture was examined for domestic refrigerators. A thermodynamic cycle analysis indicated that the propane\\/isobutane mixture in the composition range of 0.2 to 0.6 mass fraction of propane yields an increase in the coefficient of performance (COP) of up to 2.3% as compared to CFC12. For the actual tests, two commercial refrigerators of 299 and

Dongsoo Jung; Chong-Bo Kim; Kilhong Song

2000-01-01

66

Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators  

NASA Astrophysics Data System (ADS)

The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the mixtures for achieving liquid nitrogen temperature range will be presented. Secondly, some important conclusions from the optimization of various mixed-refrigerant J-T cycles such as a simple J-T cycle and an auto-cascade mixed-refrigerant J-T cycle will be presented. Moreover, an auto-cascade, mixed-refrigerant J-T refrigerator with a special mixture capable of achieving about 50K will be mentioned. Finally, various prototypes based on the mixed-refrigerant refrigeration technology will be described. These applications include miniature J-T cryocoolers for cooling infrared detectors and high-temperature superconducting devices, cryosurgical knife for medical treatment, low-temperature refrigerators for biological storage and so forth. The on-going research work and unanswered questions for this technology will be also discussed.

Luo, E.; Gong, M.; Wu, J.; Zhou, Y.

2004-06-01

67

Thermophysical properties of HFC-143a and HFC-152a. Quarterly report, 1 July 1993--30 September 1993  

SciTech Connect

Numerous fluids have been identified as promising alternative refrigerants, but much of the information needed to predict their behavior as pure fluids and as components in mixtures does not exist. In particular, reliable thermophysical properties data and models are needed to predict the performance of the new refrigerants in heating and cooling equipment and to design and optimize equipment to be reliable and energy efficient. Objective of this project is to provide highly accurate, selected thermophysical properties data for refrigerants HFC-143a (CH{sub 3}CF{sub 3}) and HFC-152a (CH{sub 3}CHF{sub 2}) and to use these data to fit complex equations of state and detailed transport property models. The new data will fill gaps in the existing data sets and resolve problems and uncertainties that exist in and between the data sets.

Haynes, W.M.

1993-10-01

68

Performance of a new refrigeration cycle using refrigerant mixture R32\\/R134a for residential air-conditioner applications  

Microsoft Academic Search

In this paper, a new refrigeration cycle (NRC) using the binary non-azeotropic refrigerant mixture R32\\/R134a is presented, which can be an alternative refrigeration cycle applied in residential air-conditioner. In the NRC, refrigerant circuit of the evaporator is separated into two branches. Because the non-azeotropic mixture has the characteristic of temperature glide, an important benefit of such configuration is that the

Jianyong Chen; Jianlin Yu

2008-01-01

69

Comparative study of two phase flow boiling of refrigerant mixtures and pure refrigerants inside enhanced surface tubing  

SciTech Connect

In this paper, the characteristics of two phase flow boiling of pure refrigerant; R-22 as well as non-azeotropic refrigerant mixtures R-22/R-114 and R-22/R-152a inside horizontal enhanced surface tubing is presented. Correlations were proposed to predict the heat transfer characteristics of non-azeotropic refrigerant mixture flow boiling inside enhanced surface tubing. In addition, it was found that the enhancement of the heat transfer coefficient is dependent on the mixture components and their concentrations.

Sami, S.M.; Schnotale, J. (Mechanical Engineering, School of Engineering, Univ. of Moncton, Moncton, New Brunswick E1A 3E9 (CA))

1992-01-01

70

Experimental Determination of Forced Convection Evaporative Heat Transfer Coefficients for Non-Azeotropic Refrigerant Mixtures.  

National Technical Information Service (NTIS)

A number of experiments were conducted in the 1960's to determine the two phase heat transfer coefficient, h TP of pure refrigerants. Recently energy conservation requirements spurred interest in nonazeotropic refrigerant mixtures, because such mixtures c...

D. Didion H. Ross R. Radermacher

1983-01-01

71

Heat exchanger thermal performance for two nonazeotropic refrigerant mixtures.  

National Technical Information Service (NTIS)

Two nonazeotropic refrigerant mixtures (NARMs), the first consisting of 71% R22 and 29% R114 and the second consisting of 75% R143a and 25% R124 (approximate percentages by mass), were studied at various mass flow rate and heat loads in an experimental ap...

J. C. Conklin E. A. Vineyard

1991-01-01

72

EVALUATION OF OZONE-FRIENDLY HYDROFLUOROPROPANE-BASED ZEOTROPIC REFRIGERANT MIXTURES IN A LORENZ-MEUTZNER REFRIGERATOR/FREEZER  

EPA Science Inventory

The two-evaporator (located in the freezer and fresh food compartments) design of the Lorenz-Meutzner (L-M) refrigerator/freezer (R/F) makes it a leading candidate for use of zeotropic refrigerant mixtures. Zeotrophic mixtures can have significant temperature glides during evapor...

73

Chemical and thermal stability of refrigerant-lubricant mixture with metal. Materials compatibility and lubricants research on CFC-refrigerant substitutes: Quarterly report, 1 February 1992--31 March 1992  

SciTech Connect

This report presents completed sealed tube stability test results for the R-123/mineral oil mixture and preliminary results for seven of the eighteen contracted refrigerant-lubricant mixtures. The R-123 mixture was tested at 105, 150, and 175{degrees}C. The results obtained indicate that prolonged exposure to temperatures of about 150{degree}C and higher will lead to rapid chemical deterioration of the R-123/mineral oil system. Chlorotrifluoroethane (R-133a) and trifluoroethane (R-143a) have been identified as decomposition products of R-123. Testing at 150 and 175{degrees}C have been completed for the HCFC refrigerants R-22, R-124, and R-142b with either mineral oil or alkylbenzene lubricants. These mixtures were very stable at the indicated temperatures. Testing at a higher temperature level will be necessary to define their upper temperature limits. Similarily, partial test results are available for HFC refrigerants R-32, R-125, R-134a (two esters), and R-143a with pentaerythritol ester lubricants at the 150 and 175{degrees}C temperature levels. Again, all five mixtures were found to be extremely stable at the test temperatures and additional testing will be needed to establish their upper temperature limits.

Huttenlocher, D.F. [Spauschus Associates, Inc., Atlanta, GA (United States)

1992-03-31

74

Measurement of vapor–liquid equilibria for the binary mixture of propylene (R-1270) + 1,1,1,2-tetrafluoroethane (HFC134a)  

Microsoft Academic Search

Isothermal vapor–liquid equilibria data for the binary mixture of propylene (R-1270) + 1,1,1,2-tetrafluoroethane (HFC-134a) at five equally spaced temperatures between 273.15 and 313.15K were measured by using a circulation-type equilibrium apparatus. The experimental data were correlated with the Peng–Robinson equation of state (PR-EOS) combined with the Wong–Sandler mixing rule. It was confirmed that the data calculated by this equations of

Quang Nhu Ho; Byung Gwon Lee; Ji-Young Park; Jae-Duck Kim; Jong Sung Lim

2004-01-01

75

Investigation of the starting modes of the low-temperature refrigerating machines working on the mixtures of refrigerants  

Microsoft Academic Search

The starting mode of a small low-temperature Joule–Thomson refrigerating machine is in focus of the experimental investigation reported here. The refrigerating machine operates by the Linde cycle. A mixture of hydrocarbons – isobutane\\/ethane\\/methane – is used as a refrigerant. The object of cooling is a small testing chamber to be cooled down and thermostabilized at the temperature level of (?70,

Andrey Rozhentsev; Vjacheslav Naer

2009-01-01

76

Effect of mixture composition and hardware on the performance of a single stage JT refrigerator  

NASA Astrophysics Data System (ADS)

The specific refrigeration effect that can be obtained in a single stage mixed refrigerant Joule-Thomson refrigerator is strongly dependent on the composition of mixture used. Comprehensive methods have been developed over the last two decades to determine the mixture composition that results in the highest exergy efficiency or the refrigeration produced. However, what is not well known is the relationship between the mixture composition and the hardware, which ultimately decides the performance of the refrigerator. Experiments were conducted with seven different nitrogen-hydrocarbon mixtures in a single stage JT refrigerator to understand the effect of both composition and hardware on the performance of the refrigerator, the results of which are presented in this paper.

Lakshmi Narasimhan, N.; Venkatarathnam, G.

2011-08-01

77

Heat transfer evaluation of HFC-236ea and CFC-114 in condensation and evaporation. Final report, October 1992-March 1995  

SciTech Connect

The report gives results of a heat transfer evaluation of the refrigerants hexafluoropropane (HFC-236ea) and 1,1,2,2-dichloro-tetrafluoroethane (CFC-114). This research focuses on comparing the refrigerants not only in condesation and pool boiling, but also with various tube surfaces. The test facility used in this study was initially used for spray evaporation testing; however, it was redesigned and modified for use with condensation, pool boiling, or spray evaporation testing. During condensation, the rig was capable of producing saturated or superheated vapor. During pool boiling or spray evaporation, the test facility was capable of testing pure refrigerants or refrigerant/lubricant mixtures.

Huebsch, W.W.; Pate, M.B.

1996-06-01

78

Some Correlations for Saturated-Liquid Density of Refrigerant Mixtures  

NASA Astrophysics Data System (ADS)

Three methods to correlate and estimate the saturated-1iquid density of refrigerant mixtures are compared and evaluated on the basis of the measurements for five bibary and one ternary mixtures performed by the present authors. The first of them is a method using Peng-Robinson equation (PR-method) proposed originally by Peneloux et al. Since this method dose not require any measurements of the saturated-liquid density of mixture, it is useful for the estimation. However, the applicability of this method to various substances may be restricted. The second is the modified Rackett equation proposed by Spencer and Dannar (mR-method). The temperature functional form of this equation is quite simple, so it is useful to use it as a functional form of the fitting. Unfortunately this method can not be used for strongly non-ideal mixtures. The last one is the Hankinson-Brobst-Thomson equation (HBT-method). This method can provide the most accurate density values among the three methods with two kinds of binary parameters where these binary parameters are introduced by the present authors. In the case that many experimental saturated liquid densities of mixtures are available in the wide range of temperatures, the HBT-method is recommended for the practical use.

Maezawa, Yukishige; Sato, Haruki; Watanabe, Koichi

79

Prediction of two phase flow condensation of pure and refrigerant mixtures on enhanced surface tubing  

SciTech Connect

In this paper, the heat transfer characteristics of two phase flow condensation of pure refrigerants, as well as non-azeotropic refrigerant mixtures R-22/R-114 and R-22/R-152a, on horizontal enhances surface tubing is presented. Results showed that the enhancement of the heat transfer depends on the mixture components and their concentrations.

Sami, S.M.; Schnotale, J. (Mechanical Engineering School of Engineering, Univ. of Moncton, Moncton, New Brunswick E1A 3E9 (CA))

1992-03-01

80

Performance analysis of the natural mixture R744\\/R600a refrigeration cycle  

Microsoft Academic Search

Environmental conservation issue advances the refrigerant substitute for the Freons. Natural working fluid must be a perfect choice. Therefore, natural friendly refrigerants R744 and R600a are selected in this research to be a binary mixture. Such a mixture can weaken their shortcomings by decreasing high heat rejection pressure as that of pure R744, and reducing flammability as that of pure

Xianping Zhang; Aidong Chen; Huanlin Duan

2010-01-01

81

Flow regimes of refrigerant mixtures condensing inside tubes  

NASA Astrophysics Data System (ADS)

In order to take full advantage of the energy-conservation potential of refrigerant mixtures, the heat-transfer coefficients should be maintained high. More insight was sought into the condensation process by observing and photographing the flow regimes of the nonazeotropic mixed refrigerants condensing in a single-tube glass condenser. Measurements of pressure and temperature profiles through the condenser as well as chromatographic analysis of samples at several points along the condenser were taken. The four principal flow regimes from the entrance to the exit of the condenser are: annular flow, stratified flow, slug flow, and bubble flow. The most significant reduction in heat-transfer coefficient occurred in the midrange of the condenser on the operating system, and the regime was shown in the glass condenser to be stratified flow. Several explanations for the reduction in heat-transfer coefficient are selective diffusivity, temperature and concentration gradients, and vapor-liquid slip. Slip was prominent in the region where the major reduction in heat-transfer coefficient occurred, so inhibiting this slip may prevent at least some of the heat-transfer degradation.

Kornota, E.; Stoecker, W. F.

1985-06-01

82

Influence of Refrigerant Oil on Evaporator Performance  

NASA Astrophysics Data System (ADS)

Because of the phase-out CFC Freon series required by Montreal Protocal, the conversion to HFC alternatives for vapor compression refrigeration system have been in progress. The each component design of these system should need to be reassessed, however, to improve the performance and compactness of the evaporator, an influence of the refrigerant oil on the refrigerant side heat transfer remains as an important and unsolved subject. In this article, the previous research progresses on the thermophysical properties, two-phase flow regimes and heat transfer in evaporator tube of refrigerant and oil mixture are briefly reviewed and the ability of these results to the combination of the alternative refrigerant and oil system is discussed. According to the review, the limited quantitative agreements were obtained from the perfect miscible refrigerant and oil mixture and, in particular, the much detailed research on the heat transfer mechanisms are required in future.

Kim, Jong Soo; Katsuta, Masafumi

83

Boiling Heat Transfer and Pressure Drop of Non-Azeotropic Mixtures Inside a Horizontal Grooved Tube  

NASA Astrophysics Data System (ADS)

The evaporation of HCFC141b, HFC152a and HFC23, and non-azeotropic refrigerant mixture used at the very low temperature refrigeration system is experimentally studied in a horizontal spirally grooved tube with corrugation. The experiments were conducted at 0.03 to 0.47MPa of boiling pressure, 100 kg/(m2s) of mass flux, 1 to 15 kW/ m2 of heat flux, -26 to 21 °C of refrigerant temperature and 11.4 mm of average inner diameter. It is concluded that boiling heat transfer coefficients of single-refrigerant are higher than these of non-azeotropic refrigerant mixture. And dimensionless correlation of the heat transfer coefficirnts, i.e. Lockhart-Martinelli parameters agreed with equation (10) within the limit of ±40 percent. Pressure drops of these refrigerant mixture depend on its liquid density and flow pattern.

Kajikawa, Satoru; Ayukawa, Kyozo; Sogo, Motosuke; Okita, Yuji

84

SIMULATION OF NON-AZEOTROPIC REFRIGERANT MIXTURES FOR USE IN A DUAL-CIRCUIT REFRIGERATOR/FREEZER WITH COUNTERCURRENT HEAT EXCHANGES  

EPA Science Inventory

The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. This RF is housed in a stan...

85

Heat exchanger thermal performance for two nonazeotropic refrigerant mixtures  

NASA Astrophysics Data System (ADS)

Two nonazeotropic refrigerant mixtures (NARMs), the first consisting of 71 percent R22 and 29 percent R114 and the second consisting of 75 percent R143a and 25 percent R124 (approximate percentages by mass), were studied at various mass flow rates and heat loads in an experimental apparatus at Oak Ridge National Laboratory. The measured thermal performance of the evaporator and the condenser are presented in terms of the number of transfer units (NTU) and effectiveness epsilon. Because the phase-change process of the NARMs is nonisothermal, a specific heat for the two-phase region can be defined. This two-phase specific heat for the NARMs varies with respect to enthalpy. Because the standard NTU-(epsilon) analysis is valid only for constant specific heat fluids, an analysis that considers variable specific heat fluids is used to compare analytical predictions of the thermal performance with the observed thermal performance. The predicted and measured results show very good agreement when the pressure drop is low.

Conklin, J. C.; Vineyard, E. A.

1991-08-01

86

Cycle performance comparison between a nonazeotropic refrigerant mixture and R22.  

National Technical Information Service (NTIS)

In an effort to improve the efficiency of residential heat pumps and reduce the ozone depletion potential (ODP) of the refrigerant, nonazeotropic mixtures (NARMs) are being investigated as part of the Building Equipment Research program at Oak Ridge Natio...

E. A. Vineyard J. C. Conklin

1991-01-01

87

Heat transfer coefficients in two-phase flow for mixtures used in solar absorption refrigeration systems  

Microsoft Academic Search

This paper describes the experimental results obtained on the heat transfer in saturated nucleate boiling of refrigerant mixtures used in solar absorption refrigeration systems flowing upward in a uniformly heated vertical tube. The mixtures analysed were water\\/ammonia, ammonia\\/lithium nitrate and water\\/lithium bromide. The concentration range for the water\\/ammonia was from 38 to 48wt%, for the ammonia\\/lithium nitrate was from 38

W Rivera; V Vélez; A Xicale

2000-01-01

88

Experimental study of the refrigeration cycle performance for the R744\\/R290 mixtures  

Microsoft Academic Search

A new binary mixture of R744 and R290 as an alternative natural refrigerant to R13 was first presented in this paper. Its environmental performance is friendly. It has an ODP of zero and GWP smaller than 20. Experimental studies for this mixture and R13 were performed on a cascade refrigeration system only with modification to capillary in low-temperature circuit. COP

Baolian Niu; Yufeng Zhang

2007-01-01

89

Application of the Carnahan-Starling-DeSantis equation of state to mixtures of refrigerants  

SciTech Connect

A modification to the Carnahan-Starling equation of state to describe the properties of refrigerant materials and their binary and ternary mixtures is discussed. A detailed discussion of the ability to fit and predict the thermodynamic properties of R22 is included. The representations arising from limited and extensive data sets are compared. The binary mixture R22/R114 is discussed and compared briefly to other binary refrigerant mixtures. The ability of this model to describe ternary mixtures without any ternary information is discussed. Present uses of this model are described.

Morrison, G.; Mc Linden, M.O.

1987-01-01

90

Experimental investigation on mixed refrigerant Joule-Thomson cryocooler with flammable and non-flammable refrigerant mixtures  

NASA Astrophysics Data System (ADS)

The mixed refrigerant Joule-Thomson (MR J-T) cryocoolers have a wide application area covering the temperature range from 80 K to 200 K. The significant advantages of the system are simplicity of its design and working reliability with high level performance. The present paper discusses the experimental results of MR J-T cooler with different flammable and non-flammable mixture compositions. The work highlights the use of pressure-enthalpy and temperature-enthalpy diagrams for these mixtures to support the experimental results. A record lowest temperature of 65 K and a cooling capacity of 6 W at 80 K are obtained for a single stage MR J-T system starting at 300 K. Further, using a mixture of minimum flammable refrigerants, temperatures below 100 K is achieved.

Walimbe, N. S.; Narayankhedkar, K. G.; Atrey, M. D.

2010-10-01

91

Relationship between the cooldown characteristics of J-T refrigerators and mixture composition  

NASA Astrophysics Data System (ADS)

The performance of Joule-Thomson (J-T) refrigerators is strongly influenced by the composition of the refrigerant mixture used. The mixture composition changes if leaks occur, or when a silica-gel drier is used in the system. In this experimental study, we show how the composition changes can be estimated from the cooldown characteristics of J-T refrigerators without using a gas chromatograph. A novel way of representing the cooldown characteristics of J-T refrigerators is presented. The variation of compressor power during the cooldown is also discussed. The results presented here are useful for developers as well as field service engineers in selectively modifying the composition without discarding the entire mixture.

Rajesh Reddy, K.; Srinivasa Murthy, S.; Venkatarathnam, G.

2010-06-01

92

Simulation of nonazeotropic refrigerant mixtures for use in a dual-circuit refrigerator/freezer with countercurrent heat exchangers  

SciTech Connect

The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, this RF appears to provide energy savings of 24%, compared to current U.S. RF designs. The NARMs modeled with the best performance included R-32/-152a, R-22/-142b, and R-32/-142b. An 18% improvement can be expected from the dual-circuit system using R-12 alone, and an additional 6% improvement can be gained by replacing R-12 with the selected NARMs in countercurrent heat exchangers. The advantages of the system include greatly reduced energy consumption, easy temperature and humidity control for each compartment, no humidity or odors transferred between compartments, and increased time between defrost cycles.

Bare, J.C.; Gage, C.L.; Radermacher, R.; Jung, D.

1991-01-01

93

Flow Regimes of Refrigerant Mixtures Condensing inside Tubes.  

National Technical Information Service (NTIS)

This study sought more insight into the condensation process by observing and photographing the flow regimes of the same nonazeotropic mixed refrigerants condensing in a single-tube glass condenser. Measurements of pressure and temperature profiles throug...

E. Kornota W. F. Stoecker

1985-01-01

94

Performance Evaluation of Chlorine Free Zeotropic Refrigerant Mixtures in Heat Pumps Computer Study and Tests.  

National Technical Information Service (NTIS)

Fifteen binary zeotropic refrigerant mixtures consisting of the components R 23, R32, R125, R134a, , R143a, and R152a are investigated as possible replacement fluids for R22. The two mixtures of R32/R134a abd R32/R152a showed COP imporvements over R22 of ...

D. A. Didion J. Pannock R. Radermacher

2003-01-01

95

FLAME SUPPRESSION AND LUBRICANT INTERACTION OF HYDROCARBON MIXTURES FOR HOUSEHOLD REFRIGERANT/FREEZERS  

EPA Science Inventory

The paper discusses the flame suppression and lubricant interaction of hydrocarbon (HC) mixtures for household refrigerator/freezers (R/Fs). he work focuses on blending the minimum amount of a fluoroiodocarbon (FIC) with previously optimized R/F-tested HC mixtures to reduce their...

96

FLAME SUPPRESSION AND LUBRICANT INTERACTION OF HYDROCARBON MIXTURES FOR HOUSEHOLD REFRIGERATOR/FREEZERS  

EPA Science Inventory

The paper discusses the flame suppression and lubricant interaction of hydrocarbon (HC) mixtures for household refrigerator/freezers (R/Fs). The work focuses on blending the minimum amount of a fluoroiodocarbon (FIC) with previously optimized R/F-tested HC mixtures to reduce thei...

97

Thermodynamic Properties of the Mixtures R23\\/R744 and R41\\/R744 and their Efficiency as Refrigerants  

Microsoft Academic Search

Mixtures of refrigerants are widely used as working substances for refrigerating plants. Among them, mixtures of ozone-safe and natural refrigerants, in particular R23\\/R744 and R41\\/R744, are important. For calculating their thermodynamic properties, we compiled equations of state on the basis of the method in (1). According to this reference, the equation of state for a mixture is presented as a

Aleksandr Vasserman C; Valentine Malchevsky S

98

Experimental investigation on mixed refrigerant Joule–Thomson cryocooler with flammable and non-flammable refrigerant mixtures  

Microsoft Academic Search

The mixed refrigerant Joule–Thomson (MR J–T) cryocoolers have a wide application area covering the temperature range from 80K to 200K. The significant advantages of the system are simplicity of its design and working reliability with high level performance. The present paper discusses the experimental results of MR J–T cooler with different flammable and non-flammable mixture compositions. The work highlights the

N. S. Walimbe; K. G. Narayankhedkar; M. D. Atrey

2010-01-01

99

TRANSPORT PROPERTY MEASUREMENTS OF HFC-236EA  

EPA Science Inventory

The report gives results of an evaluation of transport properties of 1, 1, 1, 2, 3, 3-hexafluoropropane (HFC-236ea), with liquid viscosity and thermal conductivity being the two main transport properties of interest. In addition, the specific heat and density of refrigerant/lubri...

100

TRANSPORT PROPERTY MEASUREMENTS OF HFC-236EA  

EPA Science Inventory

The report gives results of an evaluation of transport properties of 1,1,1,2,3,3,-hexafluoropropane (HFC-236ea), with liquid viscosity and thermal conductivity being the two main transport properties of interest. In addition, the specific heat and density of refrigerant/lubrican...

101

The Effect of Circuiting Arrangement on the Thermal Performance of Refrigeration Mixtures in Tube-and-Fin Condensing Heat Exchangers  

SciTech Connect

For the pure or azeotropic refrigerants typically used in present air conditioning and refrigeration applications, the refrigerant changes phase at a constant temperature. Thus, the refrigerant circuiting arrangement such as crossfiow, counterfiow, or cross-counterflow, has no effect on the thermal performance. For zeotropic refrigerant mixtures, however, the phase-change occurs over a temperature range, or "glide", and the refrigerant circuiting arrangement, or flow path through the heat exchanger, can affect the thermal performance of both the heat exchangers as well as the overall efficiency of the vapor compression cooling cycle. The effects of tsvo diflerent circuiting arrangements on the thermal performance of a zeotropic retligerant mixture and an almost azeotropic refrigerant mixture in a four-row cross-countertlow heat exchanger arrangement are reported here. The two condensers differ only in the manner of circuiting the refrigerant tubes, where one has refrigerant always flowing downward in the active heat transfer region ("identical order") and the other has refrigerant alternating flow direction in the active heat transfer region ("inverted order"). All other geometric parameters, such as bce are% fin louver geometry, refrigerant tube size and enhancement etc., are the same for both heat exchangers. One refrigerant mixture (R-41OA) un&rgoes a small temperature change ("low glide") during phase change, and the other retligerant mixture (a multi- component proprietary mixture) has a substantial temperature change ("high glide") of approximately 10"C during the phase change process. The overall thermal conductance, two-phase conductance, and pressure drop are presented. For the flow conditions of these tests, which are representative of resi&ntial cooling conditions, inverted order circuiting is more desirable than identical order. The potential thermal advantages of the i&ntical order arrangement for high-glide zeotropic refrigerant mixtures are negated by the increased parasitic refrigerant-side pressure drop utiortunately resulting from tkbrication requirements of the identical order circuiting.

Chen, D.T.; Conklin, J.C.

1999-03-15

102

New concepts for refrigerant leak detection and mixture measurement.  

National Technical Information Service (NTIS)

Since the discovery that chlorofluorocarbons (CFCs) destroy the ozone layer, the need to reduce the release of these refrigerants into the environment has become critical. A total ban of ozone-depleting CFCs is expected within a few years, and hydrofluoro...

F. C. Chen, S. L. Allman, C. H. Chen

1993-01-01

103

TESTING OF REFRIGERANT MIXTURES IN RESIDENTIAL HEAT PUMPS  

EPA Science Inventory

The report gives results of an investigation of four possibilities for replacing Hydrochlorofluorocarbon-22 (HCFC-22) with the non-ozone-depleting new refrigerants R-407D and R-407C in residential heat pumps. The first and simplest scenario was a retrofit with no hardware modific...

104

Flow boiling heat transfer with HFC mixtures in a smooth horizontal tube. Part II: Assessment of predictive methods  

Microsoft Academic Search

In tube heat transfer characteristics of R410A and R404A have been experimentally investigated in a smooth horizontal tube made of stainless steel with an inner diameter of 6 mm and a length of 6 m, uniformly heated by the Joule effect. The evaporation pressures has been varied within the range from 3 to 12 bar, the refrigerant mass flux within

A. Greco; G. P. Vanoli

2005-01-01

105

Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators  

Microsoft Academic Search

The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the

E. Luo; M. Gong; J. Wu; Y. Zhou

2004-01-01

106

Accelerated screening methods for determining chemical and thermal stability of refrigerant-lubricant mixtures, Part 1: Method assessment. Final report  

SciTech Connect

This report presents results of a literature search performed to identify analytical techniques suitable for accelerated screening of chemical and thermal stabilities of different refrigerant/lubricant combinations. Search focused on three areas: Chemical stability data of HFC-134a and other non-chlorine containing refrigerant candidates; chemical stability data of CFC-12, HCFC-22, and other chlorine containing refrigerants; and accelerated thermal analytical techniques. Literature was catalogued and an abstract was written for each journal article or technical report. Several thermal analytical techniques were identified as candidates for development into accelerated screening tests. They are easy to operate, are common to most laboratories, and are expected to produce refrigerant/lubricant stability evaluations which agree with the current stability test ANSI/ASHRAE (American National Standards Institute/American Society of Heating, Refrigerating, and Air-Conditioning Engineers) Standard 97-1989, ``Sealed Glass Tube Method to Test the Chemical Stability of Material for Use Within Refrigerant Systems.`` Initial results of one accelerated thermal analytical candidate, DTA, are presented for CFC-12/mineral oil and HCFC-22/mineral oil combinations. Also described is research which will be performed in Part II to optimize the selected candidate.

Kauffman, R.

1993-04-01

107

Modeling of an intermittent solar absorption refrigeration system operating with ammonia–lithium nitrate mixture  

Microsoft Academic Search

The theoretical performance of an intermittent absorption refrigeration system operating with ammonia–lithium nitrate mixture is presented. The analysis was done for representative days of each season of 2001. Meteorological data were taken from a local meteorological station installed in the Energy Research Centre of the National University of Mexico in Temixco, Morelos, Mexico. The system consists of a generator-absorber, a

C. O Rivera; W Rivera

2003-01-01

108

Human Safety and Pharmacokinetics of the CFC Alternative Propellants HFC 134a (1,1,1,2-Tetrafluoroethane) and HFC 227 (1,1,1,2,3,3,3-Heptafluoropropane) Following Whole-Body Exposure  

Microsoft Academic Search

HFC 134a (1,1,1,2-tetrafluoroethane) and HFC 227 (1,1,1,2,3,3,3-heptafluoropropane) are used to replace chlorofluorocarbons (CFCs) in refrigerant and aerosol applications, including medical use in metered-dose inhalers. Production and consumption of CFCs are being phased out under the Montreal Protocol on Substances that Deplete the Ozone Layer. The safety and pharmacokinetics of HFC 134a and HFC 227 were assessed in two separate double-blind

H. H. Emmen; E. M. G. Hoogendijk; W. A. A. Klöpping-Ketelaars; H. Muijser; E. Duistermaat; J. C. Ravensberg; D. J. Alexander; D. Borkhataria; G. M. Rusch; B. Schmit

2000-01-01

109

Simulation of nonazeotropic refrigerant mixtures for use in a dual-circuit refrigerator/freezer with countercurrent heat exchanges  

SciTech Connect

The paper discusses the simulation of Non-azeotropic Refrigerant Mixtures (NARMs) for use in a dual-circuit refrigerator/freezer (RF) with countercurrent heat exchangers. The simulated RF has two complete and independent refrigeration cycles for its two compartments. It uses a NARM in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, the RF is simulated to provide energy savings of 24 percent compared to current U.S. RF designs. The NARMs modeled with the best performance are R-32/-152a, R-32/-142b, and R-22/-142b. An 18 percent improvement can be expected from the dual-circuit system using R-12 alone, and an additional 6 percent improvement can be gained by replacing R-12 with the selected NARMs in countercurrent heat exchangers. Advantages of the system include greatly reduced energy consumption, easy temperature and humidity control for each compartment, no humidity or odors transferred between compartments, and increased time between defrost cycles. Disadvantages include additional hardware requirements, compressor size, and the difficulties of using a NARM.

Bare, J.C.; Gage, C.L.; Radermacher, R.; Jung, D.S.

1992-01-01

110

40 CFR Appendix D to Subpart B of... - SAE J2810 Standard for Recovery Only Equipment for HFC-134a Refrigerant  

Code of Federal Regulations, 2010 CFR

...Mode and Effects Analysis in Design (Design FMEA) and Potential Failure Mode and Effects Analysis...Manufacturing and Assembly Processes (Process FMEA) and Effects Analysis for Machinery (Machinery FMEA). SAE J1771Criteria for Refrigerant...

2009-07-01

111

40 CFR Appendix D to Subpart B of... - SAE J2810 Standard for Recovery Only Equipment for HFC-134a Refrigerant  

Code of Federal Regulations, 2010 CFR

...Mode and Effects Analysis in Design (Design FMEA) and Potential Failure Mode and Effects Analysis...Manufacturing and Assembly Processes (Process FMEA) and Effects Analysis for Machinery (Machinery FMEA). SAE J1771Criteria for Refrigerant...

2010-07-01

112

40 CFR Appendix D to Subpart B of... - SAE J2810 Standard for Recovery Only Equipment for HFC-134a Refrigerant  

Code of Federal Regulations, 2010 CFR

...Mode and Effects Analysis in Design (Design FMEA) and Potential Failure Mode and Effects Analysis...Manufacturing and Assembly Processes (Process FMEA) and Effects Analysis for Machinery (Machinery FMEA). SAE J1771Criteria for Refrigerant...

2012-07-01

113

40 CFR Appendix D to Subpart B of... - SAE J2810 Standard for Recovery Only Equipment for HFC-134a Refrigerant  

Code of Federal Regulations, 2010 CFR

...Mode and Effects Analysis in Design (Design FMEA) and Potential Failure Mode and Effects Analysis...Manufacturing and Assembly Processes (Process FMEA) and Effects Analysis for Machinery (Machinery FMEA). SAE J1771Criteria for Refrigerant...

2011-07-01

114

Effects of synthetic oil in a compression refrigeration system using R410A. Part II: quality of heat transfer and pressure losses within the heat exchangers  

Microsoft Academic Search

The consequences of the oil rejected by the compressor of a vapour-compression refrigeration system on the operation of the evaporator and condenser are analysed. The modelled prototype uses the mixture of HFC R410A and a synthetic polyolester (POE) oil. The rise of the amount of lubricant circulating in the system leads to a progressive change in the behaviour of the

O. Lottin; P. Guillemet; J.-M. Lebreton

2003-01-01

115

Thermal Conductivity of Nonazeotropic Gaseous Mixtures of Fluorocarbon Refrigerants  

NASA Astrophysics Data System (ADS)

The thermal conductivity of four binary gaseous mixtures of R22 (CHCIF2) with R13(CClF3), R23(CHF3), R12(CCl2F2) and R114(CClF2·CClF2) has been measured at temperatures 298.15 and 323.15K under pressures from atmospheric to saturated pressures by a coaxial cylinder cell. The precision of the thermal conductivity obtained is within 2%. The thermal conductivity of mixtures increases with increasing temperature and pressure at a constant composition. The thermal conductivity in each mixture changes almost linearly with the concentration of R22 at a constant temperature and pressure, although the thermal conductivity at each composition is slightly larger than the calculated values by a simple molefraction average method. The experimental results were correlated with composition and pressure by empirical equations and compared with several kinds of prediction methods. The Brokaw's equation is found to reproduce the experimental data most successfully with a mean deviation of 0.7%.

Tanaka, Yoshiyuki; Ueno, Hiroshi; Kubota, Hironobu; Makita, Tadashi

116

An extension to the UNIFAC group assignment for prediction of vapor-liquid equilibria of mixtures containing refrigerants  

Microsoft Academic Search

All previously published vapor-liquid equilibrium data points for binary mixtures containing fluorinated hydrocarbons have been taken into account to develop an extension to the UNIFAC group assignment for common refrigerants. It is shown that ten new main groups are necessary to describe all the various forms of halogenated refrigerants. The accuracy of this extension is within the range usually obtained

Michael Kleiber

1995-01-01

117

Flow boiling heat transfer coefficients at cryogenic temperatures for multi-component refrigerant mixtures of nitrogen-hydrocarbons  

NASA Astrophysics Data System (ADS)

The recuperative heat exchanger governs the overall performance of the mixed refrigerant Joule-Thomson cryocooler. In these heat exchangers, the non-azeotropic refrigerant mixture of nitrogen-hydrocarbons undergoes boiling and condensation simultaneously at cryogenic temperature. Hence, the design of such heat exchanger is crucial. However, due to lack of empirical correlations to predict two-phase heat transfer coefficients of multi-component mixtures at low temperature, the design of such heat exchanger is difficult.

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

118

NEW CHEMICAL ALTERNATIVE FOR OZONE-DEPLETING SUBSTANCES: HFC-236FA  

EPA Science Inventory

The report gives results of a preliminary evaluation of a new hydrofluorocarbon (HFC)--HFC-236fa or 1,1,1,3,3,3-hexafluoropropane--as a possible alternative for chlorofluorocarbon (CFC)-114 (1,2-dichloro-1,1,2,2-tetrafluoroethane) refrigerant for chillers and as a possible fire s...

119

Efficiency of vapor compression heat pumps based on non-azeotropic refrigerant mixtures  

NASA Astrophysics Data System (ADS)

The work presents the results of cycle computation for vapor compression pumps based on ozone-safe mixed refrigerants. Non-azeotropic binary refrugerants R32/R152a (30/70) and R32/R134a (30/70) were considere as working substances. Properties of non-azeotropic refrigerants were calculated according to the additivity method of thermodynamic functions and method of Lemmon and Jacobsen. Deviations in the values of thermophysical properties obtained with two methods have been determined. It is shown that at the use of nonazeotropic mixture R32/R152a (30/70), energy conversion ratio increases by 2.2-3.6 % compared with the results for R32/R134a (30/70) at temperature difference between the processes of boiling and condensation from 28 to 53 °C.

Mezentseva, N. N.

2011-06-01

120

Evaluation of HFC 245ca and HFC 236ea as foam blowing agents  

NASA Technical Reports Server (NTRS)

Hydrochlorofluorocarbon (HCFC) 141b has been selected as the interim blowing agent for use in urethane insulations on NASA's Space Shuttle External Tank. Due to the expected limited commercial lifetime of this material, research efforts at the NASA Thermal Protection Systems Materials Research Laboratory at the Marshall Space Flight Center are now being devoted to the identification and development of alternatives with zero ozone depletion potential. Physical blowing agents identified to date have included hydrocarbons, fluorocarbons, hydrofluoroethers, and more predominantly, hydrofluorocarbons (HFCs). The majority of the HFC evaluations in industry have focused on the more readily available, low boiling candidates such as HFC 134a. Higher boiling HFC candidates that could be handled at ambient conditions and use current processing equipment would be more desirable. This paper will describe results from a research program of two such candidate HFC's performed as a cooperative effort between Martin Marietta Manned Space Systems, the U.S. Environmental Protection Agency, and Oak Ridge National Laboratories. The purpose of this effort was to perform a cursory evaluation of the developmental HFC's 245ca and 236ea as blowing agents in urethane based insulations. These two materials were selected from screening tests of 37 C2, C3, and C4 isomers based on physical properties, atmospheric lifetime, flammability, estimated toxicity, difficulty of synthesis, suitability for dual use as a refrigerant, and other factors. Solubility of the two materials in typical foam components was tested, pour foaming trials were performed, and preliminary data were gathered regarding foam insulation performance.

Sharpe, Jon; Macarthur, Doug; Kollie, Tom; Graves, Ron; Liu, Matthew; Hendriks, Robert V.

1995-01-01

121

Experimental investigation on the thermal stability of some new zero ODP refrigerants  

Microsoft Academic Search

Five zero ODP (ozone depletion potential) hydro-fluorocarbon refrigerants (HFC-23, HFC-143a, HFC-227ea, HFC-236fa, HFC-245fa) were tested to define their maximum usable temperature and their thermal degradation threshold. Pyrolysis is detected (a) as a pressure change at constant temperature and volume; (b) as a departure of the vapour pressure curve of the heated fluid from that of the original substance. Visual inspection

Gianfranco Angelino; Costante Invernizzi

2003-01-01

122

Influence of ultrasound on pool boiling heat transfer to mixtures of the refrigerants R23 and R134A  

Microsoft Academic Search

The effect of ultrasound on pool boiling heat transfer to mixtures of the refrigerants R23 and R134a has been investigated in a wide range of heat flux and saturation pressure. The enhancement of the heat transfer coefficient, which can be achieved by ultrasound, is much more pronounced for mixtures than for pure substances. It is, however, limited to rather small

Stefan Bonekamp; Konrad Bier

1997-01-01

123

Heat transfer coefficients in two phase flow for the water\\/lithium bromide mixture used in solar absorption refrigeration systems  

Microsoft Academic Search

This paper describes the experimental results obtained from the heat transfer in saturated nucleate boiling for the water\\/lithium bromide mixture flowing upward in a uniformly heated vertical tube, which is the generator of a solar absorption refrigeration system. The concentration range for the mixture was from 48 to 56wt.% Plots of local and average heat transfer coefficients are shown against

W. Rivera; A. Xicale

2001-01-01

124

Pool boiling heat transfer of refrigerant mixtures R32/R125  

SciTech Connect

Nucleate pool boiling heat transfer of new, environmentally harmless refrigerant mixtures R32/R125 has been systematically investigated in a wide range of pressure and heat flux under saturation conditions using a horizontal platinum wire (d = 0.1 mm). The platinum wire served as both heating element and resistance thermometer. The experimental results are compared with calculated values using a modified Jungnickel correlation. The comparison between all calculated data and experimental data shows good agreement. Most of the data fall within {+-}20% of the correlation. The mean average deviation is {+-}8.25%.

Shen, J.; Spindler, K.; Hahne, E.

1999-11-01

125

Thermal Conductivity of the Refrigerant Mixtures R404A, R407C, R410A, and R507A  

Microsoft Academic Search

New thermal conductivity data of the refrigerant mixtures R404A, R407C, R410A, and R507C are presented. For all these refrigerants, the thermal conductivity was measured in the vapor phase at atmospheric pressure over a temperature range from 250 to 400 K and also at moderate pressures. A modified steady-state hot-wire method was used for these measurements. The cumulative correction for end

V. Z. Geller; B. V. Nemzer; U. V. Cheremnykh

2001-01-01

126

Assessment of propane\\/commercial butane mixtures as possible alternatives to R134a in domestic refrigerators  

Microsoft Academic Search

The possibility of using hydrocarbon mixtures as working fluids to replace R134a in domestic refrigerators has been evaluated through a simulation analysis in the present work. The performance characteristics of domestic refrigerators were predicted over a wide range of evaporation temperatures (?35 to ?10°C) and condensation temperatures (40–60°C) for various working fluids such as R134a, propane, commercial butane and propane\\/iso-butane\\/n-butane

M. Fatouh; M. El Kafafy

2006-01-01

127

Refrigeration Circuit Employed New Refrigerant  

NASA Astrophysics Data System (ADS)

There is urgent need to develop alternative refrigerants following the amendments to the Fourth Montreal Protocol regarding the regulation for HCFC's that is effective from January 1, 1996, and eventual the phase out of HCFC's production, currently scheduled for the year 2030. These alternative refrigerant shave less affect to ward the global environment, but are required to meet many conditions such as safety, thermal characteristics, stability, price, energy efficiency, behavior with lubricants and materials and so on. This report explains the current status of evaluation of candidates, and suggest about what is the best way to choice the best alternative refrigerant for the Air-conditioners, including the environmentally acceptability and safety. And explain the development for technologies to make good use of new HFC refrigerants and issues for them.

Ohnishi, Haruo

128

Thermal conductivity of alternative refrigerants in the liquid phase  

SciTech Connect

Measurements of the thermal conductivity of five alternative refrigerants, namely, difluoromethane (HFC-32), pentafluoroethane (HFC-125), 1,1,1-trifluorethane (HFC-143a), and dichloropentafluoropropanes (HCFC-225ca and HCFC-225cb), are carried out in the liquid phase. The range of temperature is 253-324 K for HFC-32, 257-305 K for HFC-125, 268-314 K for HFC-134a, 267-325 K for HCF-225ca, and 286-345 K for HCFC-225cb. The pressure range is from saturation to 30 MPa. The reproducibility of the data is better than 0.5%, and the accuracy of the data is estimated to be of the order of 1%. The experimental results for the thermal conductivity of each substance are correlated by an equation which is a function of temperature and pressure. A short discussion is given to the comparison of the present results with literature values for HFC-125. The saturated liquid thermal conductivity values of HFC-32, HFC-125, and HFC-143a are compared with those of chlorodifluoromethane (HCFC-22) and tetrafluoroethane (HFC-134a) and it is shown that the value of HFC-32 is highest, while that of HFC-125 is lowest, among these substances. The dependence of thermal conductivity on number of fluorine atoms among the refrigerants with the same number of carbon and hydrogen atoms is discussed.

Yata, J.; Hori, M. [Kyoto Inst. of Technology (Japan); Kobayashi, K. [Kobe Steel Co., Ltd. (Japan); Minamiyama, T. [Fukyuama Univ. (Japan)

1996-05-01

129

Thermal conductivity of alternative refrigerants in the liquid phase  

NASA Astrophysics Data System (ADS)

Measurements ofthe thermal conductivity of five alternative refrigerants. namely, difluoromethane HFC-321. pentafluoroethane (HFC-125), 1,1,1-trifluoroethane (HFC-143a), and dichloropentafluoropropanes (HCFC-225ca and HCFC-225cb). are carried out in the liquid phase, The range of temperature is 253 324 K for HFC-32, 257 305 K for HFC-125, 268 314 K for HFC-134a. 267 325 K for HCFC-225ca, and 286 345 K for HCFC-225cb, The pressure rank is from saturation to 30 MPa, The reproducibility of the data is better than 0.5% and the accuracy of the data is estimated to be of the order of 1%. The experimental results for the thermal conductivity ofeach substance are correlated by an equation which is a function of temperature and pressure. A short discussion is given to the comparison of the present results with literature values for HFC-125, The saturated liquid thermal conductivity values of HFC-32. HFC-125, and HFC-143a are compared with those of chlorodifluoromethane (HCFC-22) and tetrafluoroethane (HFC-134a) and it is shown that the value of HFC-32 is highest, while that of HFC-125 is lowest, among these substances, The dependence of thermal conductivity on number of fluorine atoms among the refrigerants with the same number of carbon and hydrogen atoms is discussed.

Yata, J.; Hori, M.; Kobayashi, K.; Minamiyama, T.

1996-05-01

130

Occupational exposure to fluorinated hydrocarbons during refrigeration repair work.  

PubMed

This study describes refrigeration repair workers' occupational exposures to halogenated refrigerants, focusing on difluorochloromethane (HCFC 22), tetrafluoroethane (HFC 134a) and a mixture of tri-, tetra- and pentafluoroethane (R404A) in 30 work operations. Unlike earlier reported studies, the present study includes working procedures involving welding in order to measure possible occupational exposure to decomposition products. The measurements included hydrogen fluoride (HF), hydrogen chloride (HCl), phosgene (COCl2) and volatile organic compounds (VOC). The exposures were assessed during work operations on small-scale cooling installations like refrigerators and freezers. The repair workers' occupational exposures to refrigerants were moderate, and the major part of the exposures were associated with specific working procedures lasting for relatively short periods of time (<20 min). During these exposure events the concentrations were occasionally high (up to 42434 mg m(-3)). Although welding operations lasted only for short periods of time, HF was detected in 9 out of 15 samples when HCFC 22, HFC 134a or R404A had been used. Hydrogen chloride was detected in 3 out of 5 samples in air polluted with HCFC 22. Phosgene was not detected. A large number of VOCs in various concentrations were found during welding. Except for the applied refrigerants, halogenated compounds were only found in one sample. PMID:12729261

Gjølstad, Merete; Ellingsen, Dag G; Espeland, Oscar; Nordby, Karl-Christian; Evenseth, Harald; Thorud, Syvert; Skaugset, Nils Petter; Thomassen, Yngvar

2003-04-01

131

Blends of carbon dioxide and HFCs as working fluids for the low-temperature circuit in cascade refrigerating systems  

Microsoft Academic Search

This paper describes an analysis on the performances of a cascade refrigeration cycle operated with blends of carbon dioxide (CO2, or R744) and hydrofluorocarbons (HFC) as the low-temperature working fluid. The aim of this work was to study the possibility of using carbon dioxide mixtures in those applications where temperatures below CO2 triple point (216.58K) are needed. The analysis was

Giovanni Di Nicola; Giuliano Giuliani; Fabio Polonara; Roman Stryjek

2005-01-01

132

Experimental surface tensions for HFC-32, HCFC-124, HFC-125, HCFC-141b, HCFC-142b, and HFC-152a  

NASA Astrophysics Data System (ADS)

The surface tension of six alternative refrigerants, i.e., HFC-32 (CH, F, ). HCFC-124 (CHClFCF,), HFC-125 (CHF2CF3). HCFC-14lb ICH,CCI,F). HCFC-142b (CH3CCIF2), and HFC-152a (CH3CHF2), has been measured in the present study. The measurements were conducted under equilibrium conditions between the liquid and its saturated vapor. The differential capillary-rise method (DORM) used two glass capillaries, with inner radii of 0.3034 ± 0.0002 and 0.5717 ±0.0002 mm, respectively. Temperatures in the range from 270 to 340 K were considered. The accuracy of surface tension measurements is estimated to be within ±0.2 mN · m-1. The temperatures are accurate to within ±20 mK. The temperature dependence of the resultant data were successfully represented by van der Waals' correlations to within ±(1.1 mN m-1 for each substance. Available surface tension data are compared with the present data.

Okada, M.; Higashi, Y.

1995-05-01

133

Vapor-Liquid Equilibrium Measurements of the Binary R32+R125 Refrigerant Mixture  

NASA Astrophysics Data System (ADS)

Vapor-liquid equilibrium (VLE) data of the binary R32+R125 refrigerant mixture including R410A (50mass% R32 + 50mass% R125) were obtained by the circulation-type experimental apparatus with a liquid-bath thermostat. VLE measurements were carried out in the temperatures between 263.15 K and 318.15 K and in the pressures between 505 kPa and 2724 kPa. The experimental uncertainties of temperature, pressure, and composition measurements were estimated to be within 3 mK, 0.1 %, and 0.4 %, respectively. The present data were compared with reported experimental data against the REFPROP 6.01 as well as REFPROP 7.0 calculation results.

Higashi, Yukihiro; Miyake, Takeshi; Fujii, Ken-Ichi

134

Vapour-liquid equilibrium of ternary mixtures of the refrigerants R32, R125 and R134a  

Microsoft Academic Search

Ternary mixtures of R32, R125 and R134a of different compositions are recommended for replacing refrigerants R22 and R502. As a prerequisite for reliably calculating vapour pressure and phase equilibria of ternary mixtures within the relevant range of temperature and composition, VLE data of the three binary systems R32\\/R134a, R125\\/R134a and R32\\/R125 have been measured from ?70°C up to the critical

M Nagel; K Bier

1995-01-01

135

Solubility, viscosity and density of refrigerant/lubricant mixtures. Quarterly technical progress report, 1 January--31 March 1993.  

National Technical Information Service (NTIS)

This report presents results for low refrigerant concentration (70, 80, 90 and 100 weight percent lubricant) mixtures of the following fluids: CFC-12/ISO 32 naphthenic mineral oil, HCFC-22/ISO 32 naphthenic mineral oil, CFC-12/ISO 100 naphthenic mineral o...

D. R. Henderson

1993-01-01

136

COMPARISON OF CFC-114 AND HFC-236EA PERFORMANCE IN SHIPBOARD VAPOR COMPRESSION SYSTEMS  

EPA Science Inventory

The report gives results of a comparison of the performance of two refrigerants - 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and 1,2-dichloro-tetrafluoroethane (CFC-114) - in shipboard vapor compression refrigeration systems. (NOTE: In compliance with the Montreal Protocol and Dep...

137

A refrigeration system for supermarkets using natural refrigerant CO 2  

Microsoft Academic Search

This paper describes a refrigeration system using a natural refrigerant that has been developed to reduce significantly both direct and indirect greenhouse gas emissions. The new system uses both R-404A and CO2<\\/sub> (R-744) as refrigerants. The new system has very low global warming potential compared with conventional HFC systems which reduces significantly direct emissions. Indirect emissions are also much reduced

A. Campbell; G. G. Maidment; J. F. Missenden

2007-01-01

138

New chemical alternative for ozone-depleting substances: HFC-236ea. Final report, November 1996-March 1997  

SciTech Connect

The report gives results of a preliminary evaluation of a new hydrofluoro-carbon (HFC-236ea or 1,1,1,2,3,3-hexafluoropropane) as a possible alternative for chlorofluorocarbon (CFC)-114 (1,2-dichloro-1, 1,2,2-tetrafluoroethane) refrigerant in chillers and high-temperature industrial heat pumps. Evaluation tests included an examination of the flammability, stability, thermophysical properties, lubricant/refrigerant characteristics, materials compatibility, inhalation toxicity, and refrigeration performance. HFC-236ea was found to be an excellent alternative for CFC-114 refrigerant.

Brna, T.G.; Smith, N.D.; Hendriks, R.V.; Gage, C.L.

1997-10-01

139

A method for estimating the composition of the mixture to be charged to get the desired composition in circulation in a single stage JT refrigerator operating with mixtures  

NASA Astrophysics Data System (ADS)

It has been shown earlier in literature that the composition of the mixture in circulation at steady state is different from that charged into the system in Joule-Thomson refrigerators operating with mixtures. There are no methods in literature that help us charge a particular composition into the system in order to get the desired composition in circulation at steady state. Experiments were performed with 30 different charge compositions, two different heat exchangers, and two different heat loads to understand the relationship between the composition in circulation and that charged. Based on these experiments, a method is proposed for estimating the charge composition required to get the desired composition in circulation.

Lakshmi Narasimhan, N.; Venkatarathnam, G.

2010-02-01

140

Thermophysical Properties of a Quaternary Refrigerant Mixture: Comparison of Dynamic Light Scattering Measurements with a Simple Prediction Method  

Microsoft Academic Search

Dynamic light scattering (DLS) has been used for the measurement of several thermophysical properties of a quaternary refrigerant\\u000a mixture R-125\\/143a\\/32\\/134a in its liquid phase under saturation conditions. The thermal diffusivity and sound speed have been\\u000a obtained by light scattering from bulk fluids over a temperature range from about 293 K up to the liquid–vapor critical point.\\u000a By applying the method of

Andreas Paul Fröba; Cristina Botero; Heiko Kremer; Alfred Leipertz

2007-01-01

141

Anwendung der UNIFAC-Methode zur Vorausberechnung der Verdampfungsgleichgewichte von Kaeltemittelgemischen. (Application of the UNIFAC method for the precalculation of evaporation equilibria of refrigerant mixtures).  

National Technical Information Service (NTIS)

Considering the ozone problem, great importance is placed on the search of suitable substitutional materials for the presently used refrigerants in the future. Short-term alternatives could be represented by refigerant mixtures, consisting of a fully and ...

J. Storm

1989-01-01

142

Immediate opportunity for large greenhouse gas emissions reductions with new mobile air conditioning refrigerants  

Microsoft Academic Search

Vehicle air conditioning, or “mobile air conditioning” (MAC), has a significant impact on the Earth's climate. HFC-134a, the predominant refrigerant in today's MAC, has a global warming potential (GWP) of 1430. MAC is responsible for a third of global HFC emissions and is the single largest user of HFC-134a. Fortunately, three technically and economically feasible low-GWP refrigerant alternatives exist, making

Kristen N. Taddonio

2010-01-01

143

The use of an MHV-2 equation of state for modeling the thermodynamic properties of refrigerant mixtures  

SciTech Connect

This paper reports on the development and application of a thermodynamic model based on the second-order Modified Huron Vidal equation of state (MHV-2) to predict the properties of ternary mixtures of the refrigerants R32, R125, and R134a. The mixing rules of this equation of state have been used to incorporate directly an activity-coefficient model for the excess Gibbs free energy. The parameters for the activity-coefficient model have been derived from experimental VLE data for binary mixtures. This methodology has enabled the production of a thermodynamically consistent model which can be used to predict the phase equilibria of R32/R125/R134a mixtures. The input data used in the model are presented in the paper and the predictions of the model are compared with available experimental data. The model has been used to predict the behavior of ternary refrigerant blends of R32/R125/R134a in fractionation scenarios, such as liquid charging and vapor leakage, which are of direct interest to the refrigeration industry. Details of these applications and comparisons with experimental data are discussed, along with other general uses of the thermodynamic model.

Morrison, J.D.; Barley, M.H.; Parker, I.B. [Runcorn Technical Centre, Cheshire (United Kingdom)] [and others

1995-09-01

144

Experimental study of the heat transfer characteristics of refrigerant mixture R-22/R-114 in the annulus of enhanced surface tubing  

SciTech Connect

In this paper an experimental study of heat transfer characteristics of refrigerant mixture R-22/R-114 in the annuli of a horizontal enhanced surface tubing evaporator is presented. The enhanced surface tubing data showed a significant enhancement of the heat transfer compared to an equivalent smooth tube depending on the mixture's components and their concentrations. Correlations were proposed to predict the average heat transfer coefficients of R-22/R114 non-azeotropic refrigerant moisture flow boiling inside enhanced surface tubing.

Sami, S.M.; Duong, T.N. (Mechanical Engineering, School of Engineering, Univ. of Moncton, Moncton, New Brunswick E1A 3E9 (CA))

1991-07-01

145

Thermophysical Properties of the Refrigerant Mixtures R417A and R417B from Dynamic Light Scattering (DLS)  

NASA Astrophysics Data System (ADS)

Dynamic light scattering (DLS) has been used for the measurement of several thermophysical properties of the refrigerant mixtures R417A (50 % by mass 1,1,1,2-tetrafluoroethane—R134a, 46.6 % pentafluoroethane—R125, 3.4 % n-butane—R600) and R417B (79 % by mass R125, 18.25 % R134a, 2.75 % R600). Both refrigerant mixtures are designed for a replacement of R22 (chlorodifluoromethane) in existing refrigeration systems. Thermal diffusivity and sound speed have been obtained by light scattering from the bulk fluid for the liquid phase under saturation conditions over a temperature range from about 283 K up to the liquid-vapor critical point with estimated uncertainties between 1 % and 3 % and between 0.5 % and 2 %, respectively. By applying the method of DLS to a liquid-vapor interface, also called surface light scattering, the saturated liquid kinematic viscosity and surface tension have been determined simultaneously. These properties have been measured from 253.15 K up to the liquid-vapor critical point with estimated uncertainties between 1 % and 3 % for kinematic viscosity and between 1 % and 2 % for surface tension. The measured thermal diffusivity, sound speed, kinematic viscosity, and surface tension are represented by interpolating expressions with differences between the experimental and calculated values that are comparable with but always smaller than the uncertainties. The results are discussed in detail in comparison with literature data and with various prediction methods.

Heller, A.; Rausch, M. H.; Flohr, F.; Leipertz, A.; Fröba, A. P.

2012-03-01

146

Performance and Simulation of Once-Through and Separating Cycles Using Nonazeotropic Refrigerant Mixtures.  

National Technical Information Service (NTIS)

A simulation program developed at the University of Illinois at Urbana-Champaign was refined to match the performance of an experimental refrigeration facility located in the laboratory of the Department of Mechanical and Industrial Engineering in which t...

D. Boggs W. F. Stoecker

1986-01-01

147

Vapor-liquid equilibria for the difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a) system  

SciTech Connect

Isothermal vapor-liquid equilibrium data of the binary mixture of difluoromethane (HFC-32) + 1,1,1,2-tetrafluoroethane (HFC-134a) have been measured in the temperature range between 263 K and 323 K. The experiment was carried out with a circulation type apparatus with the measurement of temperature, pressure, and compositions of the liquid and vapor phases. The experimental data were correlated with the Peng-Robinson and Redlich-Kwong-Soave equations of state, and comparison with literature results has been made.

Chung, E.Y.; Kim, M.S. [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering] [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering

1997-11-01

148

Energy and global warming impacts of next generation refrigeration and air conditioning technologies  

Microsoft Academic Search

Significant developments have occurred in hydrofluorocarbon (HFC) and the application of ammonia and hydrocarbons as refrigerant working fluids since the original TEWI (Total Equivalent Warming Impact) report in 1991. System operating and performance data on alternative refrigerants and refrigeration technologies justify and updated evaluation of these new alternative refrigerants and competing technologies in well-characterized applications. Analytical and experimental results are

J. R. Sand; S. K. Fischer; V. D. Baxter

1996-01-01

149

HEAT TRANSFER EVALUATION OF HFC-236EA AND CFC-114 IN CONDENSATION AND EVAPORATION  

EPA Science Inventory

The report gives results of a heat transfer evaluation of the refrigerants hexafluoropropane (HFC-236ea) and 1,1,2,2-dichloro-tetrafluoroethane (CFC-114). (NOTE: With the mandatory phase-out of chlorofluorocarbons (CFCs), as dictated by the Montreal Protocol and Clean Air Act Ame...

150

NEW CHEMICAL ALTERNATIVE FOR OZONE-DEPLETING SUBSTANCES: HFC-236EA  

EPA Science Inventory

The report gives results of a preliminary evaluation of a new hydrofluorocarbon (HFC-236ea or 1, 1, 1, 2, 3, 3-hexafluoropropane) as a possible alternative for chlorofluorocarbon (CFC)-114 (1, 2-dichloro-1, 1, 2, 2-tetrafluoroethane) refrigerant in chillers and high-temperature i...

151

Growth of HFC-143a (CH3CF3) determined from in-situ observation at AGAGE observatories.  

NASA Astrophysics Data System (ADS)

High frequency, in-situ observation from the Advanced Global Atmospheric Gases Experiment (AGAGE) and System for the Observation of Greenhouse Gases in Europe (SOGE) networks for the period 2004 to 2008 have been used to capture the rapid growth of the HFC-143a (CH3CF3) in the atmosphere. These measurements indicate that the atmospheric accumulation has increased considerably since the only other reported measurements by Culbertson et al. (2004) indicated levels of 2ppt in 1997. The growth rate was 1.1 ppt/year (13%/yr) in 2008. The mole fraction in the lower troposphere in 2008 is estimated to be 8.5 ppt. The rapid increase is the effect of the phaseout of the HCFC compounds under the Montreal Protocol and the increased usage of HFC-143a in mixtures for commercial refrigeration as its main application. The extensive observations have been combined with a range of modelling techniques to derive global and regional emission estimates in a top down approach, which can be compared to bottom up estimates of emissions based on production and consumption data. This independent verification of emissions is vital in assessing the effectiveness of international treaties such as the Kyoto protocol.

O'Doherty, Simon

2010-05-01

152

Alternatives for CFC-12 refrigerant in automotive air conditioning. Report for October 1996-March 1997  

SciTech Connect

Ten refrigerants including CFC-12, HFC-134a, and eight refrigerant blends were tested in an instrumented automotive air-conditioning system designed for CFC-12. The refrigerants were compared at three test conditions for refrigeration capacity, coefficient of performance, compressor discharge pressure, compressor discharge temperature, and evaporator outlet pressure. The results were obtained by testing all the refrigerants in the same system under the same conditions, and the results provide an indication of the comparative performance of the refrigerants.

Jetter, J.J.; Delafield, F.R.

1997-12-31

153

New chemical alternative for ozone-depleting substances: HFC-236fa. Final report, December 1996-April 1997  

SciTech Connect

The report gives results of a preliminary evaluation of a new hydrofluoro-carbon (HFC)--HFC-236fa or 1,1,1,3,3,3-hexafluoropropane--asa possible alternative for chlorofluorocarbon (CFC)-114 (1,2-dichloro-1, 1,2,2-tetrafluoroethane) refrigerant for chillers and asa possible fire suppressant replacement for halon-1301 (bromotrifluoromethane). Evaluation tests included an examination of flammability, stability, atmospheric lifetime, thermophysical properties, lubricant miscibility and solubility, materials compatibility, inhalation toxicity, refrigerant performance, heat transfer characteristics, and flame suppression.

Smith, N.D.; Brna, T.G.; Gage, C.L.; Hendriks, R.V.

1997-07-01

154

Acute neurobehavioral effects in rats from exposure to HFC 134a or CFC 12.  

PubMed

1,1,1,2-Tetrafluoroethane (HFC 134a), a chlorine-free hydrofluoroalkane, is internationally replacing billions of pounds of dichlorodifluoromethane (CFC 12) for coolant, refrigerant and aerosol propellant applications. The ALC50 for HFC 134a in rats is 567,000 ppm for 4 h; its potential for cardiac epinephrine sensitization in beagle dogs is acceptable (75,000 ppm); and its capacity to induce carcinogenicity or developmental disorders in animals is minimal. HFC 134a, with a serum half life estimated at 4-11 min, has been accepted for use as a propellant in metered-dose inhalant products, implying a low human toxicity risk from periodic brief exposures. There has been little published human or animal research evaluating possible neurobehavioral toxicity from longer HFC 134a exposures, as may be expected to occur in operational scenarios. In this study, male Wistar rats were exposed to various concentrations of HFC 134a or CFC 12 for up to 30 min while performing in either a rotarod/motorized running wheel apparatus or in an operant chamber The relative neurobehavioral toxicity of CFC 12 and its ozone-depleting substance replacement HFC 134a was assessed by comparing both gross motor system incapacitation and more subtle changes in ability to perform an operant discrimination task. It was shown that exposure to HFC 134a or CFC 12 concentrations from 40,000 to 470,000 ppm, for up to 30 min, induced neurobehavioral deficits in every subject, ranging from reduced operant efficiency to apparent anesthesia. For neurobehavioral endpoints examined in these experiments, HFC 134a inhalation was shown to induce deficits more rapidly, and at lower concentrations when compared to CFC 12 exposure. PMID:11405255

Ritchie, G D; Kimmel, E C; Bowen, L E; Reboulet, J E; Rossi, J

2001-04-01

155

Evaluation of Ikon-12 (trade name) refrigerant for motor vehicle air conditioning. Report for October 1995-June 1996  

SciTech Connect

The paper gives results of an evaluation of a proprietary refrigerant, Ikon-12, as an alternative to hydrofluorocarbon (HFC)-134a for automotive air conditioning. In preliminary tests, Ikon-12 was found to be compatible with a polyolester lubricant and engineering materials. Refrigeration capacity and efficiency for Ikon-12 compared favorably to those for HFC-134a. In a preliminary durability test, Ikon-12 refrigerant showed no significant chemical breakdown after extended operation with an elevated compresssor discharge temperature.

Jetter, J.J.; Smith, N.D.; Ratanaphruks, K.; Ng, M.S.; Tufts, M.W.

1997-09-01

156

Refrigeration and thermometry of liquid 3He- 4He mixtures at very low temperatures  

NASA Astrophysics Data System (ADS)

In order to avoid possible sources of heat leaks into liquid 3He- 4He mixtures we have constructed an experimental setup using only materials of high purity. The inner part of an Ag-cell was furnished with a 700A?-Ag sinter ( A=110m 2) and two vibrating wires. The temperature of the cell wall was measured by a Pt-NMR thermometer. The temperature of the mixture was determined by the damping of the vibrating wires immersed in the pure 3He-phase of a phase-separated mixture. The achieved minimum temperature of a 6.8%-mixture at p=0.35bar is T=(130?25)?K.

Ko¨nig, R.; Pobell, F.

1994-02-01

157

Measurments of the Vapor Pressure for the Solutions of HFC-134a and Ester Based Oil  

NASA Astrophysics Data System (ADS)

The paper presents measurements of the vapor pressure for the solutions of HFC-134a and ester based oil. The oil employed is eater based synthetic lubricant that is thought to be one of the lubricants compatible with alternative refrigerant HFC-134a.The measurements have been carried out for the range of temperatures between 263.15 K and 323.15 K for the HFC134a/ester based oil solutions. The uncertainty of the measurments is estimated as ±10mK in temperature, ±5kPa in pressure and ±0.5% in concentration,respectively. Correlations that interpolate the experimental vapor pressure as a function of temperature and concentration are presented for practical use.

Takaishi, Yoshinori; Nakagawa, Hajime; Oguchi, Kosei

158

Performance of an auto refrigerant cascade refrigerator operating in gas refrigerant supply (GRS) mode with nitrogen-hydrocarbon and argon-hydrocarbon refrigerants  

NASA Astrophysics Data System (ADS)

There is a worldwide interest in the development of auto refrigerant cascade (ARC) refrigerators operating with refrigerant mixtures. Both flammable and non-flammable refrigerant mixtures can be used in these systems. The performance of an ARC system with optimum nitrogen-hydrocarbon and argon-hydrocarbon mixtures between 90 and 160 K is presented in this paper.

Gurudath Nayak, H.; Venkatarathnam, G.

2009-07-01

159

Proceedings of the 1993 non-fluorocarbon insulation, refrigeration and air conditioning technology workshop  

SciTech Connect

Sessions included: HFC blown polyurethanes, carbon dioxide blown foam and extruded polystyrenes, plastic foam insulations, evacuated panel insulation, refrigeration and air conditioning, absorption and adsorption and stirling cycle refrigeration, innovative cooling technologies, and natural refrigerants. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

Not Available

1994-09-01

160

Reproductive and developmental toxicity of hydrofluorocarbons used as refrigerants.  

PubMed

The present paper summarizes data on the reproductive and developmental toxicity of hydrofluorocarbons (HFCs), including pentafluoroethane (HFC-125), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), difluoromethane (HFC-32) and 1,1,1,3,3-pentafluoropropane (HFC-245fa), used as refrigerants, published in openly available scientific literature. No developmental toxicity of HFC-125 was found even at 50,000 ppm in rats or rabbits. Although HFC-134a exhibited no dominant lethal effect or reproductive toxicity in rats, it caused low body weight in pre- and postnatal offspring and slightly retarded skeletal ossification in fetuses at 50,000 ppm in rats. No maternal or developmental toxicity was noted after exposure to HFC-143a even at 40,000 ppm in rats or rabbits or HFC-152a even at 50,000 ppm in rats. HFC-32 is slightly maternally and developmentally toxic at 50,000 ppm in rats, but not in rabbits. HFC-245fa caused decreases in maternal body weight and food consumption at 10,000 and 50,000 ppm and fetal weight at 50 000ppm. No evidence of teratogenicity for these HFCs was noted in rats or rabbits. There is limited information about the reproductive toxicity of these HFCs. Animal studies remain necessary for risk assessments of chemicals because it is difficult to find alternative methods to determine the toxic effects of chemicals. It is required to reduce emissions of organic vapors containing HFCs to reduce the risk of exposure. PMID:19914373

Ema, Makoto; Naya, Masato; Yoshida, Kikuo; Nagaosa, Ryuichi

2010-04-01

161

Density and viscosity measurements of 1,1,1,2-tetrafluoroethane (HFC134a) from 199 K to 298 K and up to 100 MPa  

Microsoft Academic Search

New density results for liquid 1,1,1,2-tetrafluoroethane (HFC-134a) along five isotherms from 199 K to 298 K and at pressures up to 100 MPa are presented. The measurements were performed with a new vibrating-wire instrument operated in the forced mode of oscillation and were carried out on a round-robin sample of refrigerant HFC-134a. The viscosity of the fluid was measured simultaneously

A. A. H. Padua; J. M. N. A. Fareleira; J. C. G. Calado; W. A. Wakeham

1996-01-01

162

Relative permittivity measurements of 1,1,1,2-tetrafluoroethane (HFC 134a), pentafluoroethane (HFC 125), and difluoromethane (HFC 32)  

SciTech Connect

The relative permittivity of HFC 134a, HFC 32, and HFC 125 was measured as a function of temperature and pressure, to cover the liquid and gaseous states. The temperature range studied was 303 to 403 K, and the pressure range was 4.0 to 30.0 MPa. The relative permittivity, {epsilon}, could be fitted to the reduced density {rho}{sub r} using the function ({epsilon} {minus} 1)/(2{epsilon} + 1). The dipole moment of HFC 134 a in the liquid phase has been calculated.

Abbott, A.P.; Eardley, C.A.; Tooth, R. [Leicester Univ. (United Kingdom). Chemistry Dept.] [Leicester Univ. (United Kingdom). Chemistry Dept.

1999-01-01

163

The large contribution of projected HFC emissions to future climate forcing  

PubMed Central

The consumption and emissions of hydrofluorocarbons (HFCs) are projected to increase substantially in the coming decades in response to regulation of ozone depleting gases under the Montreal Protocol. The projected increases result primarily from sustained growth in demand for refrigeration, air-conditioning (AC) and insulating foam products in developing countries assuming no new regulation of HFC consumption or emissions. New HFC scenarios are presented based on current hydrochlorofluorocarbon (HCFC) consumption in leading applications, patterns of replacements of HCFCs by HFCs in developed countries, and gross domestic product (GDP) growth. Global HFC emissions significantly exceed previous estimates after 2025 with developing country emissions as much as 800% greater than in developed countries in 2050. Global HFC emissions in 2050 are equivalent to 9–19% (CO2-eq. basis) of projected global CO2 emissions in business-as-usual scenarios and contribute a radiative forcing equivalent to that from 6–13 years of CO2 emissions near 2050. This percentage increases to 28–45% compared with projected CO2 emissions in a 450-ppm CO2 stabilization scenario. In a hypothetical scenario based on a global cap followed by 4% annual reductions in consumption, HFC radiative forcing is shown to peak and begin to decline before 2050.

Velders, Guus J. M.; Fahey, David W.; Daniel, John S.; McFarland, Mack; Andersen, Stephen O.

2009-01-01

164

Positive Displacement Compressor Technology for Refrigeration  

NASA Astrophysics Data System (ADS)

Trends of compressor technologies for refrigerators, freezers and condensing units are presented in this paper. HFC refrigerants such as R134a and R404C are promising candidates as an altemative for R12. Performance of reciprocating and rotary compressors in the operation with R134A is described. In addition, compressor technologies such as efficiency improvement are described in the cases of reciprocating, rotary and scroll compressors.

Nagatomo, Shigemi

165

Lean flammability limit as a fundamental refrigerant property: Phase 3. Final technical report, February 1997--February 1998  

SciTech Connect

Alternative refrigerants are being developed by industry to prevent the further destruction of stratospheric ozone by chlorofluorocarbons (CFCs), which had been the working fluids of choice for many air-conditioning and refrigeration machines. Hydrofluorocarbons (HFCs) are one class of compounds that are being pursued as replacements because their ozone depletion potential is zero. In general, the exchange of fluorine atoms on an HFC molecule with hydrogen atoms decreases its atmospheric lifetime, and it may also increase the efficiency of the working fluid. Both of these effects are highly desirable from environmental considerations since they act to mitigate global warming. Unfortunately, more hydrogen on a HFC is usually associated with an increase in flammability. An accepted method for determining the flammability limits of gaseous fuels is ASTM Standard E 681. The minimum and maximum concentrations of the fuel in air for flame propagation are based upon the observed ignition and growth of a flame in a vessel filled with a quiescent fuel/air mixture. a Clear distinction is sought between a non-propagating flicker and a flame which has enough horizontal propagation to be hazardous. This report reviews the past work done on premixed, counter-flowing flames, describes the current counter-flow burner facility and operating procedures, presents the experimental results with the analysis that yields the above flammability limits, and recommends further activities that could lead to a science-based methodology for assessing the risk of fire from refrigeration machine working fluids. 30 figs.

Grosshandler, W.; Donnelly, M.; Womeldorf, C.

1998-08-01

166

Thermodynamic and transport properties of some alternative ozone-safe refrigerants for industrial refrigeration equipment: Study in Belarus and Ukraine  

SciTech Connect

The study of several hydrofluorocarbons (HFC) and fluorocarbons (FC) and their binary mixtures that have no ozone-depleting ability is being carried out in the framework of Belarus National program. The fluids include HFCs R134a, R152a, R125, and R32, and FC R218. The following properties are being investigated: (1) phase equilibrium parameters including the boiling and condensing curve and critical point, thermophysical properties at these parameters, and heat of evaporation; (2) isobaric and isochoric heat capacity, ethalpy, and entropy in the gas and liquid state; (3) speed of sound, thermal conductivity, viscosity, and density in the gas and liquid state; (4) dielectric properties and surface tension; (5) behavior of combined construction materials inside the refrigerant medium; and (6) solubility in compressor oils and other technological characteristics. The series of results obtained by authors during the period 1990-1993 is presented.

Grebenkov, A.J.; Klepatsky, P.M.; Beljajeva, O.V. [Inst. of Power Engineering Problems, Minsk (Belgium)] [and others

1996-05-01

167

Transport properties of refrigerants R32, R125, R134a, and R125+R32 mixtures in and beyond the critical region  

Microsoft Academic Search

A practical representation for the transport coefficients of pure refrigerants R32, R125, R134a, and R125+R32 mixtures is presented which is valid in the vapor–liquid critical region. The crossover expressions for the transport coefficients incorporate scaling laws near the critical point and are transformed to regular background values far away from the critical point. The regular background parts of the transport

S. B Kiselev; R. A Perkins; M. L Huber

1999-01-01

168

Quantification of the refrigerants R22 and R134a in mixtures by means of different polymers and reflectometric interference spectroscopy  

Microsoft Academic Search

The aim of this study was the quantification of vapors of the ozone-depleting refrigerant R22 in the presence of its most important substitute R134a, by the use of the reflectometric interference spectroscopy and polymers as sensitive layers. First, the sorption characteristic of different types of polymers exposed to the vapors of the two analytes was investigated. Then, binary mixtures of

F. Dieterle; G. Belge; C. Betsch; G. Gauglitz

2002-01-01

169

Experimental studies on HFC based two-stage half effect vapour absorption cooling system  

Microsoft Academic Search

An experimental investigation on the performance of a two-stage half effect vapour absorption cooling system has been carried out and presented. The prototype is designed for 1kW cooling capacity using HFC based working fluids (R134a as refrigerant and DMAC as absorbent). The performance of the system in terms of degassing range, coefficient of performance and second law efficiency has been

S. Arivazhagan; R. Saravanan; S. Renganarayanan

2006-01-01

170

Formation and dissociation of HFC134a gas hydrate in nano-copper suspension  

Microsoft Academic Search

The major technical issue in gas hydrates energy storage systems is how to increase the refrigerants-water mass and heat transfer and how to realize a rapid formation of clathrate hydrate. Borrowing ideas from heat transfer enhancement of the fluid with the addition of nano-sized particles, the formation and dissociation of HFC134a (CH2FCF3) hydrate were studied in nano-copper suspensions of different

Jinping Li; Deqing Liang; Kaihua Guo; Ruzhu Wang; Shuanshi Fan

2006-01-01

171

Applications of the Simple Multi-Fluid Model to Correlations of the Vapor-Liquid Equilibrium of Refrigerant Mixtures Containing Carbon Dioxide  

NASA Astrophysics Data System (ADS)

This study presents a simple multi-fluid model for Helmholtz energy equations of state. The model contains only three parameters, whereas rigorous multi-fluid models developed for several industrially important mixtures usually have more than 10 parameters and coefficients. Therefore, the model can be applied to mixtures where experimental data is limited. Vapor-liquid equilibrium (VLE) of the following seven mixtures have been successfully correlated with the model: CO2 + difluoromethane (R-32), CO2 + trifluoromethane (R-23), CO2 + fluoromethane (R-41), CO2 + 1,1,1,2- tetrafluoroethane (R-134a), CO2 + pentafluoroethane (R-125), CO2 + 1,1-difluoroethane (R-152a), and CO2 + dimethyl ether (DME). The best currently available equations of state for the pure refrigerants were used for the correlations. For all mixtures, average deviations in calculated bubble-point pressures from experimental values are within 2%. The simple multi-fluid model will be helpful for design and simulations of heat pumps and refrigeration systems using the mixtures as working fluid.

Akasaka, Ryo

172

HFC-23 (CHF3) emission trend response to HCFC-22 (CHClF2) production and recent HFC-23 emission abatement measures  

NASA Astrophysics Data System (ADS)

HFC-23 (also known as CHF3, fluoroform or trifluoromethane) is a potent greenhouse gas (GHG), with a global warming potential (GWP) of 14 800 for a 100-year time horizon. It is an unavoidable by-product of HCFC-22 (CHClF2, chlorodifluoromethane) production. HCFC-22, an ozone depleting substance (ODS), is used extensively in commercial refrigeration and air conditioning, in the extruded polystyrene (XPS) foam industries (dispersive applications) and also as a feedstock in fluoropolymer manufacture (a non-dispersive use). Aside from small markets in specialty uses, HFC-23 has historically been considered a waste gas that was, and often still is, simply vented to the atmosphere. Efforts have been made in the past two decades to reduce HFC-23 emissions, including destruction (incineration) in facilities in developing countries under the United Nations Framework Convention on Climate Change's (UNFCCC) Clean Development Mechanism (CDM), and by process optimization and/or voluntary incineration by most producers in developed countries. We present observations of lower-tropospheric mole fractions of HFC-23 measured by "Medusa" GC/MSD instruments from ambient air sampled in situ at the Advanced Global Atmospheric Gases Experiment (AGAGE) network of five remote sites (2007-2009) and in Cape Grim air archive (CGAA) samples (1978-2009) from Tasmania, Australia. These observations are used with the AGAGE 2-D atmospheric 12-box model and an inverse method to produce model mole fractions and a "top-down" HFC-23 emission history. The model 2009 annual mean global lower-tropospheric background abundance is 22.6 (±0.2) pmol mol-1. The derived HFC-23 emissions show a "plateau" during 1997-2003, followed by a rapid ~50% increase to a peak of 15.0 (+1.3/-1.2) Gg/yr in 2006. Following this peak, emissions of HFC-23 declined rapidly to 8.6 (+0.9/-1.0) Gg/yr in 2009, the lowest annual emission of the past 15 years. We derive a 1990-2008 "bottom-up" HFC-23 emission history using data from the United Nations Environment Programme and the UNFCCC. Comparison with the top-down HFC-23 emission history shows agreement within the stated uncertainties. In the 1990s, HFC-23 emissions from developed countries dominated all other sources, then began to decline and eventually became fairly constant during 2003-2008. By this point, with developed countries' emissions essentially at a plateau, the major factor controlling the annual dynamics of global HFC-23 emissions became the historical rise of developing countries' HCFC-22 dispersive use production, which peaked in 2007. Thereafter in 2007-2009, incineration through CDM projects became a larger factor, reducing global HFC-23 emissions despite rapidly rising HCFC-22 feedstock production in developing countries.

Miller, B. R.; Rigby, M.; Kuijpers, L. J. M.; Krummel, P. B.; Steele, L. P.; Leist, M.; Fraser, P. J.; McCulloch, A.; Harth, C.; Salameh, P.; Mühle, J.; Weiss, R. F.; Prinn, R. G.; Wang, R. H. J.; O'Doherty, S.; Greally, B. R.; Simmonds, P. G.

2010-08-01

173

HFC-23 (CHF3) emission trend response to HCFC-22 (CHClF2) production and recent HFC-23 emission abatement measures  

NASA Astrophysics Data System (ADS)

HFC-23 (also known as CHF3, fluoroform or trifluoromethane) is a potent greenhouse gas (GHG), with a global warming potential (GWP) of 14 800 for a 100-year time horizon. It is an unavoidable by-product of HCFC-22 (CHClF2, chlorodifluoromethane) production. HCFC-22, an ozone depleting substance (ODS), is used extensively in commercial refrigeration and air conditioning, in the extruded polystyrene (XPS) foam industries (dispersive applications) and also as a feedstock in fluoropolymer manufacture (a non-dispersive use). Aside from small markets in specialty uses, HFC-23 has historically been considered a waste gas that was, and often still is, simply vented to the atmosphere. Efforts have been made in the past two decades to reduce HFC-23 emissions, including destruction (incineration) in facilities in developing countries under the United Nations Framework Convention on Climate Change's (UNFCCC) Clean Development Mechanism (CDM), and by process optimization and/or voluntary incineration by most producers in developed countries. We present observations of lower-tropospheric mole fractions of HFC-23 measured by "Medusa" GC/MSD instruments from ambient air sampled in situ at the Advanced Global Atmospheric Gases Experiment (AGAGE) network of five remote sites and in Cape Grim air archive (CGAA) samples (1978-2009) from Tasmania, Australia. These observations are used with the AGAGE 2-D atmospheric 12-box model and an inverse method to produce model mole fractions and a "top-down" HFC-23 emission history. The model 2009 annual mean global lower-tropospheric background abundance is 22.8 (±0.2) pmol mol-1. The derived HFC-23 emissions show a "plateau" during 1997-2003, followed by a rapid ~50% increase to a peak of 15.0 (+1.3/-1.2) Gg/yr in 2006. Following this peak, emissions of HFC-23 declined rapidly to 8.6 (+0.9/-1.0) Gg/yr in 2009, the lowest annual emission of the past 15 years. We derive a 1990-2008 "bottom-up" HFC-23 emission history using data from the United Nations Environment Programme and the UNFCCC. Comparison with the top-down HFC-23 emission history shows agreement within the stated uncertainties. In the 1990s, HFC-23 emissions from developed countries dominated all other sources, then began to decline and eventually became fairly constant during 2003-2008. From the beginning of that plateau, the major factor determining the annual dynamics of global HFC-23 emissions became the historical rise of HCFC-22 production for dispersive uses in developing countries to a peak in 2007. Thereafter in 2007-2009, incineration through CDM projects became a larger factor, reducing global HFC-23 emissions despite rapidly rising HCFC-22 feedstock production in developing countries.

Miller, B. R.; Rigby, M.; Kuijpers, L. J. M.; Krummel, P. B.; Steele, L. P.; Leist, M.; Fraser, P. J.; McCulloch, A.; Harth, C.; Salameh, P.; Mühle, J.; Weiss, R. F.; Prinn, R. G.; Wang, R. H. J.; O'Doherty, S.; Greally, B. R.; Simmonds, P. G.

2010-05-01

174

Tribological Studies on Scuffing Due to the Influence of Carbon Dioxide Used as a Refrigerant in Compressors  

Microsoft Academic Search

Because hydrofluorocarbon (HFC) refrigerants in air-conditioning systems are known to have a negative effect on the environment, carbon dioxide (CO2) is a candidate as a replacement refrigerant. Research work related to CO2 as a refrigerant has been focused primarily on its thermodynamic performance, whereas work in the area of tribology related to carbon dioxide is absent. In this study, the

NICHOLAOS G. DEMAS; ANDREAS A. POLYCARPOU; THOMAS F. CONRY

2005-01-01

175

Growth of climate change commitments from HFC banks and emissions  

NASA Astrophysics Data System (ADS)

Chlorofluorocarbons (CFCs) are the primary cause of ozone depletion, and they also contribute to global climate change. With the global phaseout of CFCs and the coming phaseout of hydrochlorofluorocarbons (HCFCs), the substitute hydrofluorocarbons (HFCs) are increasingly used. While CFCs were originally used mainly in applications such as spray cans and were released within a year after production, concern about the ozone layer led to reductions in rapid-release applications, and the relative importance of slower-release applications grew. HFCs are now mainly used in refrigerators and air conditioners (AC) and are released over years to a decade after production. Their containment in such equipment represents banks, which are building up as production grows. A key finding of our work is that the increases of HFC banks represent a substantial unseen commitment to further radiative forcing of climate change also after production of the chemicals ceases. We show that earlier phaseouts of HFCs would provide greater benefits for climate protection than previously recognized, due to the avoided buildup of the banks. If, for example, HFC production were to be phased out in 2020 instead of 2050, not only could about 91-146 GtCO2-eq of cumulative emission be avoided from 2020 to 2050, but an additional bank of about 39-64 GtCO2-eq could also be avoided in 2050. Choices of later phaseout dates lead to larger commitments to climate change unless growing banks of HFCs from millions of dispersed locations are collected and destroyed.

Velders, G. J. M.; Solomon, S.; Daniel, J. S.

2014-05-01

176

Development of models for prediction of solubility for HFC working fluids in pentaerythritol ester compressor oils  

Microsoft Academic Search

This study aims to further develop a model of the group contribution type that can predict the solubility of mixtures of HFC working fluids and pentaerythritol ester compressor oils. The investigation is based on solubility data for 20 systems of five different HFCs in four different pentaerythritol esters. First, five different activity factor-based thermodynamic models were investigated to determine to

Åsa Wahlström; Lennart Vamling

2000-01-01

177

Evaporation of nonazeotropic mixture of refrigerants R143a and R124 flowing inside smooth and corrugated tubes.  

National Technical Information Service (NTIS)

Because heat exchanger thermal performance has a direct influence on the overall cycle performance of vapor-compression refrigeration machinery, enhanced heat transfer surfaces are of interest to improve the efficiency of heat pumps and air conditioners. ...

D. L. Hinton J. C. Conklin E. A. Vineyard

1992-01-01

178

Double-lift absorption refrigeration cycles driven by low–temperature heat sources using organic fluid mixtures as working pairs  

Microsoft Academic Search

At present, much interest is being shown in absorption refrigeration cycles driven by low temperature heat sources, such as solar energy or low-grade waste-heat. Double-lift absorption cycles working with ammonia-water have been recommended for refrigeration applications which require cold at 0°C and which are activated by waste heat between 70 and 100°C. This paper discusses the potential of the organic

M. Medrano; M. Bourouis; A. Coronas

2001-01-01

179

Recent increases in global HFC23 emissions  

Microsoft Academic Search

Firn-air and ambient air measurements of CHF3 (HFC-23) from three excursions to Antarctica between 2001 and 2009 are used to construct a consistent Southern Hemisphere (SH) atmospheric history. The results show atmospheric mixing ratios of HFC-23 continuing to increase through 2008. Mean global emissions derived from this data for 2006–2008 are 13.5 ± 2 Gg\\/yr (200 ± 30 × 1012

S. A. Montzka; L. Kuijpers; M. O. Battle; M. Aydin; K. R. Verhulst; E. S. Saltzman; D. W. Fahey

2010-01-01

180

40 CFR Appendix C to Subpart B of... - SAE J2788 Standard for Recovery/Recycle and Recovery/Recycle/Recharging Equipment for HFC-134a...  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false SAE J2788 Standard for Recovery/Recycle and Recovery/Recycle/Recharging Equipment for HFC-134a Refrigerant...of Part 82âSAE J2788 Standard for Recovery/Recycle and Recovery/Recycle/Recharging Equipment...

2009-07-01

181

40 CFR Appendix C to Subpart B of... - SAE J2788 Standard for Recovery/Recycle and Recovery/Recycle/Recharging Equipment for HFC-134a...  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false SAE J2788 Standard for Recovery/Recycle and Recovery/Recycle/Recharging Equipment for HFC-134a Refrigerant...of Part 82âSAE J2788 Standard for Recovery/Recycle and Recovery/Recycle/Recharging Equipment...

2010-07-01

182

Global warming impacts of ozone-safe refrigerants and refrigeration, heating, and air-conditioning technologies  

SciTech Connect

International agreements mandate the phase-out of many chlorine containing compounds that are used as the working fluid in refrigeration, air-conditioning, and heating equipment. Many of the chemical compounds that have been proposed, and are being used in place of the class of refrigerants eliminated by the Montreal Protocol are now being questioned because of their possible contributions to global warming. Natural refrigerants are put forth as inherently superior to manufactured refrigerants because they have very low or zero global warming potentials (GWPs). Questions are being raised about whether or not these manufactured refrigerants, primarily hydrofluorocarbons (HFCs), should be regulated and perhaps phased out in much the same manner as CFCs and HCFCs. Several of the major applications of refrigerants are examined in this paper and the results of an analysis of their contributions to greenhouse warming are presented. Supermarket refrigeration is shown to be an application where alternative technologies have the potential to reduce emissions of greenhouse gases (GHG) significantly with no clear advantage to either natural or HFC refrigerants. Mixed results are presented for automobile air conditioners with opportunities to reduce GHG emissions dependent on climate and comfort criteria. GHG emissions for hermetic and factory built systems (i.e. household refrigerators/freezers, unitary equipment, chillers) are shown to be dominated by energy use with much greater potential for reduction through efficiency improvements than by selection of refrigerant. The results for refrigerators also illustrate that hydrocarbon and carbon dioxide blown foam insulation have lower overall effects on GHG emissions than HFC blown foams at the cost of increased energy use.

Fischer, S.; Sand, J.; Baxter, V.

1997-12-01

183

Effect of Fin Geometry on Condensation of Zeotropic Refrigerant Mixture R407C in a Staggered Bundle of Horizontal Finned Tubes  

NASA Astrophysics Data System (ADS)

Row-by-row heat transfer data were obtained during condensation of downward-flowing refrigerant mixture R407C in a staggered bundle of horizontal finned tubes. Two kinds of conventional low-fin tubes with flat-sided annular fins and three kinds of three-dimensional fin tubes were tested. The refrigerant mass velocity ranged from 4 to 23 kg/m2s, and the condensation temperature difference from 1.5 to 12 K. At a low to medium film Reynolds number(<2000), the highest heat transfer coefficient was obtained by one of the three-dimensional fin tubes. At a high film Reynolds number(>2000), on the other hand, the highest performance was obtained by one of the low-fin tubes. For all tubes tested, the heat transfer coefficient decreased with decreasing mass velocity. On the basis of previous results for R134a, consideration was given to the characteristics of vapor phase mass transfer of R407C.

Honda, Hiroshi; Takata, Nobuo; Takamatsu, Hiroshi; Kim, Jeongsik; Usami, Keiichiro

184

Quantification of the refrigerants R22 and R134a in mixtures by means of different polymers and reflectometric interference spectroscopy.  

PubMed

The aim of this study was the quantification of vapors of the ozone-depleting refrigerant R22 in the presence of its most important substitute R134a, by the use of the reflectometric interference spectroscopy and polymers as sensitive layers. First, the sorption characteristic of different types of polymers exposed to the vapors of the two analytes was investigated. Then, binary mixtures of the two refrigerants were measured with an array set-up on the basis of six polymer sensors. The measurements were evaluated by the use of neural networks, whereby low limits of detection of 0.45 percentage volume (vol. %)for R22 and 1.45 vol. % for R134a could be established. Additionally, one polar polymer and one microporous polymer were selected for the measurements with a low-cost set-up. The quantification of R22 in the presence of R134a with this low-cost set-up was possible with a limit of detection of 0.44 vol. %, which would enable a fast and economical monitoring at recycling stations. PMID:12434242

Dieterle, F; Belge, G; Betsch, C; Gauglitz, G

2002-11-01

185

Rotary two-phase refrigeration apparatus and method  

Microsoft Academic Search

Rotary vacuum evaporation of a primary refrigerant cools a secondary refrigerant mixed with it. The secondary refrigerant does not change state and meanders through a low pressure cooling circuit for refrigeration applications. The primary refrigerant changes state and remains in a short and secure circuit. Evaporation is produced at a surface around the axis of rotation and within the mixture

McCutchen

1994-01-01

186

Refrigeration and thermometry of liquid {sup 3}He-{sup 4}He mixtures in the ballistic regime  

SciTech Connect

The ballistic regime of liquid {sup 3}He-{sup 4}He mixtures is characterized by a large mean free path {lambda} of the thermal excitations compared to the characteristic dimension of the experiment. We report on investigations of the transport properties of mixtures as well as superfluid {sup 3}He in the ballistic regime by means of the vibrating wire technique. In order to avoid possible sources of heat leaks into the liquid, the experimental setup was built as far as possible of pure materials only. The contribution of a Ag sinter to the heat leak as well as its influence on the attainable minimum temperature of the mixtures were investigated by performing measurements in two similar setups which differed in the size of the heat exchanger by about one order of magnitude. Moreover, we have used the vibrating wire partly immersed in the superfluid {sup 3}He-B phase of a phase-separated mixture as a very sensitive, continuously monitoring thermometer for liquid mixtures in their ballistic regime. The achieved minimum temperature of a 6.8%-mixture at p = 0.35 bar and of a 9.5%-mixture at p = 9.8 bar was 130 {mu}K. This value can be considered as an upper limit for the temperature of the mixtures as the damping of the vibrating wire thermometer saturates at this temperature due to its intrinsic properties.

Koenig, R.; Betat, A.; Pobell, F. [Universitaet Bayreuth (Germany)

1994-11-01

187

Performance of an auto refrigerant cascade refrigerator operating in liquid refrigerant supply (LRS) mode with different cascade heat exchangers  

NASA Astrophysics Data System (ADS)

Auto refrigerant cascade (ARC) refrigerators operating with zeotropic mixtures provide refrigeration at temperatures less than 173 K (-100 °C) using a single compressor. Different authors have suggested different cascade heat exchangers for ARC refrigerators. There is no study in literature that suggests at what temperature ranges one, two or three cascade heat exchangers are necessary. In this paper the performance of an ARC refrigerator operating in the liquid refrigerant supply mode and operating with optimized hydrocarbon mixtures and different cascade heat exchangers is studied. The optimum number of cascade heat exchangers (stages) to be used for different operating temperatures is suggested.

Gurudath Nayak, H.; Venkatarathnam, G.

2010-11-01

188

Potentially acceptable substitutes for the chlorofluorocarbons: properties and performance features of HFC-134a, HCFC-123, and HCFC-141b  

NASA Astrophysics Data System (ADS)

Potentially acceptable substitutes are known for CFC-11 and CFC-12-the most important Chlorofluorocarbons. HFC-134a could replace CFC-12 in airconditioning and refrigeration and both HCFC-123 and HCFC-141b show promise as CFC-11 substitutes. The replacement molecules all have significantly reduced greenhouse and ozone depletion potentials compared to their fully halogenated counterparts. HCFC-123 is theoretically a less efficient blowing agent than CFC-11, but 141b is more efficient. Results from experimental foaming tests confirm these relationships and show that initial insulating values are slightly lower for 141b and 123 than 11. Both substitutes are nonflammable liquids. Based on its physical properties, HFC-134a is an excellent replacement candidate for CFC-12. In addition, it is more thermally stable than CFC-12. A new family of HFC-134a compatible lubricant oils will be required. The estimated coefficient of performance (COP) of 134a is 96 98% that of CFC-12. Subacute toxicity tests show HFC-134a to have a low order of toxicity. HCFC-123 reveals no serious side effects at a concentration of 0.1% in subchronic tests and the inhalation toxicity of 141b is lower than that of CFC-11 based on a 6-h exposure. Chronic tests on all the new candidates will have to be completed for large-scale commercial use. Allied-Signal is conducting process development at a highly accelerated pace, and we plan to begin commercialization of substitutes within 5 years.

Sukornick, B.

1989-05-01

189

Overview of CFC replacement issues for household refrigeration  

NASA Astrophysics Data System (ADS)

In 1974, the famous ozone depletion theory of Rowland and Molina claimed that chlorofluorocarbons (CFCs) diffuse into the stratosphere where they are broken down by photolysis to release chlorine atoms that catalytically destroy ozone. Although the understanding of the science is still imperfect, there is little doubt that CFCs play a major role in the Antarctic ozone hole phenomenon and the decline in ozone observed in the rest of the world. Another issue that has become increasingly important is the potential of CFCs to change the earth's temperature and to modify the climate. While the main impact in global warming is made by increased concentrations of carbon dioxide, CFCs and other trace gases also contribute to this effect. In an effort to respond to the global environmental threat, a CFC protocol was adopted during a diplomatic conference in Montreal. This document, known as the Montreal Protocol, was ratified in 1988 and put into effect on January 1, 1989. In accordance with Article 6 of the Montreal Protocol, the countries that signed the agreement shall periodically assess the control measures provided for in the Protocol. As part of that assessment process, household refrigeration was investigated to determine the status of CFC-12 replacements. The conclusion was that much progress has been made towards finding a suitable replacement. Compressors designed for HFC-134a have efficiencies comparable to those for CFC-12 and acceptable reliability tests have been obtained with ester lubricants. In addition, other replacements such as R-152a and refrigerant mixtures exist, but will require more study. Cycle options, such as the Stirling cycle, may be viable, but are further out in the future. The impact of new refrigerants is expected to result in elimination of CFC-12 consumption in developed countries by 1997 and in developing countries by 2005.

Vineyard, E. A.; Roke, L.; Hallett, F.

190

Gas absorber and refrigeration system using same  

SciTech Connect

A refrigeration system is described comprising: (a) a separator for separating a refrigerant gas from a refrigerant-rich solution to produce a refrigerant-lean solution; (b) a condenser for emitting heat to thereby condense the refrigerant gas received from the separator and an evaporator for absorbing heat to thereby evaporate the condensed refrigerant gas; (c) an absorber assembly including: a precooler for precooling the refrigerant-lean solution received from the separator; a mixer for mixing the refrigerant gas from the evaporator with the precooled refrigerant-lean solution received form the precooler to thereby form a gas-solution mixture, the mixer having nozzles for allowing the refrigerant-lean solution to be injected there through into a flow of the gas-solution mixture, the nozzles being adapted to cause the refrigerant-lean solution to experience a predetermined pressure drop there across; and absorbent tubes for allowing the gas-solution mixture to flow there through while causing the refrigerant-lean solution to absorb the refrigerant gas to thereby generate a refrigerant-rich solution; (d) a solution receiver for receiving the refrigerant-rich solution through the absorber tubes and a manifold for containing an overflow through the absorber tubes during a normal operation of the refrigeration system, an upper part of the solution receiver serving to contain the refrigerant gas; (e) recycling means for controllably recycling the refrigerant gas from the solution receiver into the absorber assembly; and a solution pump for delivering the refrigerant-rich solution from the solution receiver to the separator through a generator for heating the refrigerant-rich solution.

Dehne, H.

1993-08-24

191

Speed-of-sound measurements in gaseous binary refrigerant mixtures of difluoromethane (R-32) + 1,1,1,2-tetrafluoroethane (R-134a)  

SciTech Connect

One hundred ninety-three speed-of-sound values in gaseous difluoromethane (R-32, CH{sub 2}F{sub 2}) + 1,1,1,2-tetrafluoroethane (R-134a, CF{sub 3}CH{sub 2}F) have been measured using a spherical resonator. The measurements have been carried out at temperatures from 303 K to 343 K, pressures up to 240 kPa, and mole fractions of R-32 from 0.16 to 0.90. The experimental uncertainties in the temperature, pressure, and speed of sound for the binary mixture are estimated to be not greater than {+-}8 mK, {+-}0.1 kPa, and {+-}0.0072%, respectively. The samples purified and analyzed by the manufacturers were used and were better than 99.99 mass % for R-32 and 99.98 and 99.99 mass % for two different R-134a samples. The authors have accurately determined the compositions of the binary refrigerant mixture, R-32 + R-134a, and the second acoustic virial coefficients from the speed-of-sound measurements.

Hozumi, Tsutomu; Sato, Haruki; Watanabe, Koichi [Keio Univ., Yokohama (Japan)] [Keio Univ., Yokohama (Japan)

1997-05-01

192

Pool boiling of enhanced heat transfer surfaces in refrigerant-oil mixtures and aqueous calcium sulfate solutions  

Microsoft Academic Search

Pool boiling data of structured surfaces in R113\\/3GS oil mixtures show a general decrease in heat transfer with oil concentration, degradation in performance of all surfaces at 10% oil, no change in enhancement of the structured surfaces over plain surface, and restoration of performance of the enhanced surfaces upon cleaning in denatured alcohol. Fouling data of structured surfaces in pool

L. A. Curcio; E. F. Somerscales

1994-01-01

193

Pool boiling of enhanced heat transfer surfaces in refrigerant-oil mixtures and aqueous calcium sulfate solutions.  

National Technical Information Service (NTIS)

Pool boiling data of structured surfaces in R113/3GS oil mixtures show a general decrease in heat transfer with oil concentration, degradation in performance of all surfaces at 10% oil, no change in enhancement of the structured surfaces over plain surfac...

L. A. Curcio E. F. Somerscales

1994-01-01

194

Refrigerant R134a condensation heat transfer and pressure drop inside a small brazed plate heat exchanger  

Microsoft Academic Search

This paper presents the experimental tests on HFC-134a condensation inside a small brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature and vapour super-heating are investigated.A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 20kg\\/m2s. For refrigerant mass flux lower than 20kg\\/m2s, the saturated vapour heat transfer

Giovanni A. Longo

2008-01-01

195

Mixtures  

NSDL National Science Digital Library

Mixtures allows exploration of percents through two piles of colored and uncolored chips. The user must decide how many chips to color to create the desired percentage of colored chips compared to the total pile. Mixtures is one of the Interactivate assessment explorers.

196

Experimental and theoretical study on flow condensation with non-azeotropic refrigerant mixtures of R32\\/R134a  

Microsoft Academic Search

Experiments on flow condensation have been conducted with both pure R32, R134a and their mixtures inside a tube (10 m long, 6 mm ID), with a mass flux of 131–369 kg m?2s?1 and average condensation temperature of 23–40°C. The experimental heat transfer coefficients are compared with those predicted from correlations. The maximum mean heat transfer coefficient reduction (from a linear

D. W Shao; E Granryd

1998-01-01

197

Hybrid fiber-coax (HFC) architecture overview  

NASA Astrophysics Data System (ADS)

Hybrid fiber-coax technology allows one network to deliver both traditional telephony as well as a host of broadband services including broadcast TV, cable TV, interactive TV, video-on- demand, enhanced pay-per-view, etc. This paper presents an overview of hybrid fiber-coax architecture including discussion of the components for transmission of telephony and broadband services from the headend/central office to the home. The components and architecture of an HFC system are compared to traditional telephony. An HFC system can be broken into 4 major sections: headend/central office and interoffice network, a feeder system, a distribution system, and a customer interface. The components within each of these sections include: local digital switches, host digital terminals, broadband and narrowband optical transmitters and receivers, optical nodes, power nodes, network interface units, set top terminals and several types of passives. The function of these components is reviewed as are spectrum allocation, and signal flow.

Kaplan, Blaina A.

1995-11-01

198

Phase Diagram Calculation of Gas Mixtures for Refrigeration; Reflection & Transmission Coefficients and the Effective Mass: Superconducting Proximity I-V Measurements.  

NASA Astrophysics Data System (ADS)

The efficiency of Joule-Thomson refrigerators greatly improves with the addition of hydrocarbons to nitrogen as coolant, and is highly dependent on the mixture composition. To optimize it, we calculated the mixture phase diagram using the Peng-Robinson equation of state. A program was developed to solve numerically a set of coupled non-linear equations for the equilibrium of the vapor and liquid phases of each mixture component. The program is highly efficient, quite stable, and reliable. Gases can be easily added to the program's database. We found that the cooling efficiency of the mixtures has a sharp ridge in composition space, and explain this. To better understand tunneling spectra of the high T_{rm c} cuprate superconductors, we analyzed the one-dimensional behavior of the wavefunction of a free particle striking a crystal interface. We describe the free particle using a wavepacket of plane waves, and the crystal using the Kronig-Penney model. We find that when the wavepacket is spread over many unit cells, it behaves like a free particle wavepacket striking a small potential step. The reflection and transmission coefficients are derived and one finds that they do not contain the particle's effective mass. We determine that the boundary conditions used in a standard effective mass approach must be modified to make it work. We conclude that one should not use the effective mass approximation in treating high T_{rm c} superconductor interfaces. We measured the dynamic resistance of a superconducting -normal metal-normal metal (SNN') geometry and observed that N', a superconductor at low enough temperatures, displays superconducting properties above its critical temperature. They disappear well below the critical temperature of S. We present a simple model of the proximity effect, which is self-consistent at any temperature and good for arbitrary thicknesses of N. The model shows how the superconducting gap decays with the distance from S. We observe that the proximity effect is long-ranged when the temperature is not much above the critical temperature of N'. We also present a calculation of the Andreev reflection coefficient in an SNS geometry, that may help to explain sharp resistive peaks previously observed by Holcomb.

Friedmann, Gideon

199

Physical and chemical properties of refrigeration lubricants  

SciTech Connect

The physical and chemical properties of refrigeration lubricants are discussed. Although much attention has been focused on the performance of candidate lubricants for use with hydrofluorocarbons (HFCs) in order to obtain satisfactory lubrication performance in compressors, the properties of the lubricants themselves have not been well discussed. In this paper, the properties of refrigeration lube base stocks and of lube-refrigerant mixtures are described, specifically the viscosity, density, and refrigerant solubility, the change in viscosity and density due to solution with HFCs, and the insulation properties of the base stocks and the refrigerant mixture.

Sunami, Motoshi

1999-07-01

200

Energy and global warming impacts of next generation refrigeration and air conditioning technologies  

SciTech Connect

Significant developments have occurred in hydrofluorocarbon (HFC) and the application of ammonia and hydrocarbons as refrigerant working fluids since the original TEWI (Total Equivalent Warming Impact) report in 1991. System operating and performance data on alternative refrigerants and refrigeration technologies justify and updated evaluation of these new alternative refrigerants and competing technologies in well-characterized applications. Analytical and experimental results are used to show quantitative comparisons between HFCS, HFC blends, hydrocarbons, and ammonia, used as refrigerants. An objective evaluation is presented for commercial and near commercial non-CFC refrigerants/blowing agents and alternative refrigeration technologies. This information is needed for objective and quantitative decisions on policies addressing greenhouse gas emissions from refrigeration and air conditioning equipment. The evaluation assesses the energy use and global warming impacts of refrigeration and air conditioning technologies that could be commercialized during the phase out of HCFCS. Quantitative comparison TEWI for two application areas are presented. Opportunities for significant reductions in TEWI are seen with currently known refrigerants through improved maintenance and servicing practices and improved product designs.

Sand, J.R.; Fischer, S.K.; Baxter, V.D.

1996-10-01

201

Thermionic refrigeration  

SciTech Connect

A refrigerator is described that is based upon thermionic emission. Room-temperature refrigeration is efficient when the work function of the anode is about 0.3--0.4 eV but those low values are unattainable. The refrigerator only operates at higher temperatures.

Mahan, G.D. (Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States) Solid State Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6030 (United States))

1994-10-01

202

Tiers of Service for Data Access in a HFC Architecture  

Microsoft Academic Search

This paper discusses the Hybrid Fiber-Coaxial cable TV environment as a data delivery service providing subscribers with specific levels of service. We overview HFC for data delivery and Com21's UPSTREAMS architecture for HFC data delivery using an ATM cell based format. We discuss the evaluation of levels of service for individual subscribers and the need for both new sim- ulation

Kathleen M. Nichols; Mark Laubach

1997-01-01

203

Refrigeration - Principles of Mechanical Refrigeration.  

National Technical Information Service (NTIS)

Shows the application of basic physics of heat transfer in refrigeration units. Explains how temperature changes in refrigerant passes through the expanision valve, compressor, condensor, and evaporator as it carries heat to the outside air.

1994-01-01

204

Pool boiling of enhanced heat transfer surfaces in refrigerant-oil mixtures and aqueous calcium sulfate solutions  

SciTech Connect

Pool boiling data of structured surfaces in R113/3GS oil mixtures show a general decrease in heat transfer with oil concentration, degradation in performance of all surfaces at 10% oil, no change in enhancement of the structured surfaces over plain surface, and restoration of performance of the enhanced surfaces upon cleaning in denatured alcohol. Fouling data of structured surfaces in pool boiling of sat. aq. CaSO{sub 4} solution show that effects of fouling (wall superheat changes, deposit weight) are more pronounced at 80 kW/m{sup 2} than at 10 kW/m{sup 2} heat flux; precipitation fouling show an effect within the first 2 h exposure. High flux surfaces have lower deposition weight than other surfaces; thus the deposition rate may depend strongly on wall superheat. The numerous nucleation sites of the enhanced surfaces provide more turbulent motion near the boiling surface than for the plain surface; thus the removal rate should be greater for an enhanced surface, although no removal of a deposit was ever observed.

Curcio, L.A.; Somerscales, E.F.

1994-08-01

205

Electrochemical investigations in liquid and supercritical 1,1,1,2-tetrafluoroethane (HFC 134a) and difluoromethane (HFC 32)  

Microsoft Academic Search

This communication outlines the use of HFC 134a and HFC 32 in both the liquid and supercritical states. The comparatively mild critical conditions are used to show that both of these solvents are important for studying electrochemical processes in the supercritical state. The higher polarity of these media in the supercritical state circumvent many of the problems associated with solubility,

Andrew P. Abbott; Christopher A. Eardley; John C. Harper; Eric G. Hope

1998-01-01

206

Experimental evaluation of automotive air-conditioning using HFC-134a and HC-134a  

NASA Astrophysics Data System (ADS)

An experimental study to evaluate the energy consumption of an automotive air conditioning is presented. In this study, these refrigerants will be tested using the experimental rig which simulated the actual cars as a cabin complete with a cooling system component of the actual car that is as the blower, evaporator, condenser, radiators, electric motor, which acts as a vehicle engine, and then the electric motor will operate the compressor using a belt and pulley system, as well as to the alternator will recharge the battery. The compressor working with the fluids HFC-134a and HC-134a and has been tested varying the speed in the range 1000, 1500, 2000 and 2500 rpm. The measurements taken during the one hour experimental periods at 2-minutes interval times for temperature setpoint of 20°C with internal heat loads 0, 500, 700 and 1000 W. The final results of this study show an overall better energy consumption of the HFC-134a compared with the HC-134a.

Nasution, Henry; Zainudin, Muhammad Amir; Aziz, Azhar Abdul; Latiff, Zulkarnain Abdul; Perang, Mohd Rozi Mohd; Rahman, Abd Halim Abdul

2012-06-01

207

Thermoacoustic refrigeration  

NASA Technical Reports Server (NTRS)

A new refrigerator which uses resonant high amplitude sound in inert gases to pump heat is described and demonstrated. The phasing of the thermoacoustic cycle is provided by thermal conduction. This 'natural' phasing allows the entire refrigerator to operate with only one moving part (the loudspeaker diaphragm). The thermoacoustic refrigerator has no sliding seals, requires no lubrication, uses only low-tolerance machine parts, and contains no expensive components. Because the compressor moving mass is typically small and the oscillation frequency is high, the small amount of vibration is very easily isolated. This low vibration and lack of sliding seals makes thermoacoustic refrigeration an excellent candidate for food refrigeration and commercial/residential air conditioning applications. The design, fabrication, and performance of the first practical, autonomous thermoacoustic refrigerator, which will be flown on the Space Shuttle (STS-42), are described, and designs for terrestrial applications are presented.

Garrett, Steven L.; Hofler, Thomas J.

1991-01-01

208

Literature survey of heat transfer enhancement techniques in refrigeration applications  

SciTech Connect

A survey has been performed of the technical and patent literature on enhanced heat transfer of refrigerants in pool boiling, forced convection evaporation, and condensation. Extensive bibliographies of the technical literature and patents are given. Many passive and active techniques were examined for pure refrigerants, refrigerant-oil mixtures, and refrigerant mixtures. The citations were categorized according to enhancement technique, heat transfer mode, and tube or shell side focus. The effects of the enhancement techniques relative to smooth and/or pure refrigerants were illustrated through the discussion of selected papers. Patented enhancement techniques also are discussed. Enhanced heat transfer has demonstrated significant improvements in performance in many refrigerant applications. However, refrigerant mixtures and refrigerant-oil mixtures have not been studied extensively; no research has been performed with enhanced refrigerant mixtures with oil. Most studies have been of the parametric type; there has been inadequate examination of the fundamental processes governing enhanced refrigerant heat transfer, but some modeling is being done and correlations developed. It is clear that an enhancement technique must be optimized for the refrigerant and operating condition. Fundamental processes governing the heat transfer must be examined if models for enhancement techniques are to be developed; these models could provide the method to optimize a surface. Refrigerant mixtures, with and without oil present, must be studied with enhancement devices; there is too little known to be able to estimate the effects of mixtures (particularly NARMs) with enhanced heat transfer. Other conclusions and recommendations are offered.

Jensen, M.K.; Shome, B. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Mechanical Engineering, Aeronautical Engineering and Mechanics

1994-05-01

209

Thermotile Refrigerators  

NASA Technical Reports Server (NTRS)

Thermoelectric tiles provide cooling exactly where needed. Thermotile is modular thermoelectric cooling unit that incorporates sensor and electronic circuitry in addition to thermoelectric device. Refrigerator/freezer is lined with thermotiles clipped into supporting lattices. Small fans used to circulate air in refrigerator and freezer compartments. Elimination of conventional mechanical refrigeration machinery reduces number of moving parts and completely eliminates noise and vibration. Data capabilities of thermotile refrigeration system used for diagnosis of defects or monitoring local temperatures. Thermotiles produced by automated manufacturing techniques. Custom shapes molded as needed.

Park, Brian V.

1994-01-01

210

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2011 CFR

...acetylene-propadiene mixture must have a refrigeration system without vapor compression or have a refrigeration system with the following features...separate cargo piping, vent piping, and refrigeration equipment for methyl...

2011-10-01

211

Heat transfer during condensation of HFC-134a and R-404A inside of a horizontal smooth and micro-fin tube  

SciTech Connect

In recent small and medium capacity refrigeration systems, the condenser tubes are provided with micro-fins from inside. The vapour refrigerant at the compressor outlet and the condenser inlet is in superheat state. As it advances in the condenser it is in two phases and at the outlet it is in sub cooled liquid. The heat transfer coefficient (HTC) during condensation of HFC-134a and R-404A in a smooth (8.56 mm ID) and micro-fin tubes (8.96 mm ID) are experimentally investigated. Different from previous studies, the present experiments are performed for various condensing temperatures, with superheating and sub cooling and using hermetically sealed compressor. The test runs are done at average saturated condensing temperatures ranging from 35 C to 60 C. The mass fluxes are between 90 and 800 kg m{sup -2} s{sup -1}. The experimental results indicate that the average HTC increases with mass flux but decreases with increasing condensing temperature for both smooth and micro-fin tubes. The average condensation HTCs of HFC-134a and R-404A for the micro-fin tubes were 1.5-2.5 and 1.3-2 times larger than that in smooth tube respectively. The HTCs for R-404A are less than that of HFC-134a. New correlations based on the data gathered during the experimentation for predicting condensation HTCs are proposed for wide range of operating conditions. (author)

Sapali, S.N. [Govt. College of Engineering, Department of Mechanical Engineering, Shivaji Nagar, Pune, Maharashtra 411 005 (India); Patil, Pradeep A. [AISSMS College of Engineering, Pune University, Mechanical Engineering Department, Kennedy Road, Near R.T.O., Pune, Maharashtra 411 001 (India)

2010-11-15

212

The hierarchical fair competition (HFC) model for parallel evolutionary algorithms  

Microsoft Academic Search

The HFC model for evolutionary computation is inspired by the stratified competition often seen in society and biology. Subpopulations are stratified by fitness. Individuals move from low-fitness subpopulations to higher-fitness subpopulations if and only if they exceed the fitness-based admission threshold of the receiving subpopulation, but not of a higher one. HFC's balanced exploration and exploitation, while avoiding premature convergence,

Jian Jun Hu; Erik D. Goodman

2002-01-01

213

CFC prices rise above dropping HFC prices, spread should widen  

SciTech Connect

Chlorofluorocarbon (CFC) replacement hydrofluorocarbon (HFC)-134a has gained an economic edge over CFC-12 in the U.S. says ICI Americas Chemicals & Plastics president Robin Gadsby. Although conversion costs are keeping many customers from making the switch. Gadsby says demand for HFC-134a should exceed global capacity in the mid-1990s. He adds that ICI can recoup its $430-million investment in HFCs.

Kirschner, E.

1993-12-15

214

Accelerated screening methods for determining chemical and thermal stability of refrigerant-lubricant mixtures: Part 2, Experimental comparison and verification of methods. Quarterly technical progress report, 1 March 1993--30 June 1993  

SciTech Connect

Initial research focused on conductivity measurements to perform in heated situ degradation measurements of CFC-12/mineral oil and HCFC-22/mineral oil mixtures at 175C in sealed glass tubes. Tungsten rods were sealed into round bottoms of the sealed tubes to provide electrical connections for in situ conductivity measurements. Steel, Cu and W were used as catalysts as well as conductivity probes. Conductivity measurements have been made with both ac and dc voltage inputs. Preliminary results indicate that in situ conductivity measurements correlate with refrigerant/lubricant degradation as determined by other analytical techniques (color, gas chromatography). Some of the continuous conductivity measurement tests appear to accelerate as well as monitor the refrigerant/lubricant degradation. W posts with a valve steel catalyst appear optimum combination for conductivity measurements. Ferric fluoride catalysts and differential thermal analysis were also investigated. Initial tests indicate that the ferric fluoride catalyst has potential for testing lubricant stability at temperatures lower than 175C . Differential thermal analysis have minimal potential for in situ measurements of long-term refrigerant/lubricant degradation processes.

Kauffman, R.

1993-10-01

215

Vapor-liquid equilibria for the difluoromethane (HFC-32) + 1,1,1-trifluoroethane (HFC-143a) system  

SciTech Connect

Isothermal vapor-liquid equilibrium data of the binary system of difluoromethane (HFC-32) + 1,1,1-trifluoroethane (HFC-143a) were obtained in the temperature range from 263.15 K to 313.15 K. Temperature, pressure, and compositions of the liquid and vapor phases were measured with a circulation type apparatus. The experimental data were correlated with the Canahan-Starling-De Santis, Peng-Robinson, and Redlich-Kwong-Soave equations of state.

Kim, C.N.; Park, Y.M.

2000-02-01

216

Condensation heat transfer of a pure fluid and binary mixture outside a bundle of smooth horizontal tubes. Comparison of experimental results and a classical model  

Microsoft Academic Search

The condensation of pure HFC134a and different zeotropic mixtures with pure HFC134a and HFC23 on the outside of a bundle of smooth tubes was studied. The local heat transfer coefficient for each row was experimentally determined using a test section composed by a 13×3 staggered bundle of smooth copper tubes, measuring cooling water temperature in the inlet and the outlet

M. Belghazi; A. Bontemps; J. C. Signe; C. Marvillet

2001-01-01

217

Measurement of Concentration of Refrigerant in Refrigeration Oil by Capacitance Sensor  

NASA Astrophysics Data System (ADS)

In general, refrigeration oil of good solubility with refrigerant is used in refrigeration compressors, and development of a concentration sensor of refrigerant dissolved in the oil is needed. In this study, oil and refrigerant concentrations are measured with newly developed capacitance sensor which measure the change of dielectric constant with the concentration. It is found that in most cases of oil-refrigerant combinations the dielectric constant of refrigerant is two to three times as large as that of refrigeration oil and the dielectric constant of mixtures increases linearly with the concentration of refrigerant. When measuring the refrigerant concentration of R410A, t he measurement of the concentration by the dielectric constant is also feasible as long as the composition of each refrigerant component dissolved in the oil does not change from the nominal composition. Prototypes of small sensors, such as a cylindrical type and a needle type, are developed and the performance of the needle sensor with shield is preferable. A correlation for a given oil-refrigerant mixture obtained by a large capacitance sensor is applicable for the small sensors after correcting for stray capacitance. Flow of fluid in the sensors does not affect the capacitance measured by the sensors, while bubbles due to foaming do affect the measurement.

Fukuta, Mitsuhiro; Yanagisawa, Yadashi; Ogi, Yasuhiro; Tanaka, Junya

218

Density and viscosity measurements of 1,1,1,2-tetrafluoroethane (HFC-134a) from 199 K to 298 K and up to 100 MPa  

SciTech Connect

New density results for liquid 1,1,1,2-tetrafluoroethane (HFC-134a) along five isotherms from 199 K to 298 K and at pressures up to 100 MPa are presented. The measurements were performed with a new vibrating-wire instrument operated in the forced mode of oscillation and were carried out on a round-robin sample of refrigerant HFC-134a. The viscosity of the fluid was measured simultaneously with the density, using the same vibrating-wire sensor, at temperatures above 248 K over the entire pressure range. The results are compared with recent literature data. The precision of the present values is {+-}0.03% for the density and {+-}0.6% for the viscosity. The corresponding estimated accuracies are {+-}0.05% and {+-}2.5%, respectively.

Padua, A.A.H.; Fareleira, J.M.N.A.; Calado, J.C.G. [Inst. Superior Tecnico, Lisboa (Portugal)] [Inst. Superior Tecnico, Lisboa (Portugal); Wakeham, W.A. [Imperial Coll. (United Kingdom). Dept. of Chemical Engineering and Chemical Technology] [Imperial Coll. (United Kingdom). Dept. of Chemical Engineering and Chemical Technology

1996-07-01

219

Aging of polyurethane foam insulation in simulated refrigerator walls  

SciTech Connect

Laboratory data are presented on the thermal conductivity of polyurethane foam insulation in composite test panels that simulate refrigerator walls. The test panels consisted of a steel skin, an ABS plastic liner, and a polyurethane foam core. Foam cores were produced with three different blowing agents (CFC-11, HCFC-141b, and a HCFC-142/22 blend). Periodic thermal measurements have been made on these panels over a three and one half year period in an effort to detect aging processes. Data obtained on foam encased in the panels were compared with measurements on thin foam slices that were removed from similar panels. The data show that the encapsulation of the foam in the solid boundary materials greatly reduces the aging rate. The plan is presented for a follow-on project that is being conducted on the aging of foams blown with HCFC-141b, HFC-134a, HFC-245fa, and cyclopentane.

Wilkes, K.E.; Yarbrough, D.W.; Weaver, F.J.

1997-10-01

220

Transmission design in a multimode HFC network  

NASA Astrophysics Data System (ADS)

Contemporary hybrid fiber coaxial (HFC) networks are capable of supporting a wide range of services including traditional analog video, telephony, digital video, and data services. Each service has unique performance or service requirements. This contribution examines transmission design for one such network. Pacific Bell's advanced communications network (ACN). The design methodology begins with a set of end to end service quality objectives. Network impairments, such as noise, distortion and delay, are allocated across the network elements using a set of standard network models. These models are a representative set of the actual field designs and bound the network operating parameters. Network components, headend equipment, and customer premises equipment are specified analytically or characterized empirically in relationship to the chosen impairment set. The component parameters are then included in analytical models to estimate overall network performance. In addition to the forward path transmission considerations examined by traditional coaxial network designers, other dimensions including power consumption, traffic demand, and message latency are taken into account. Analytical models are used to estimate the effects of multiple modulation schemes within the unified network. The variability introduced by on demand services such as telephony and interactive digital services changes the base computational domain from deterministic models to stochastic ones. These models are then used to set operating parameters at measurable points throughout the network for proof of performance prior to turn up, and for ongoing performance monitoring. For closure, empirical results are compared with model projections as a way of verifying and improving the predictive models.

Cambron, G. Keith

1996-11-01

221

Alternatives to ozone depleting refrigerants in test equipment  

NASA Technical Reports Server (NTRS)

This paper describes the initial results of a refrigerant retrofit project at the Aerospace Guidance and Metrology Center (AGMC) at Newark Air Force Base, Ohio. The objective is to convert selected types of test equipment to properly operate on hydrofluorocarbon (HFC) alternative refrigerants, having no ozone depleting potential, without compromising system reliability or durability. This paper discusses the primary technical issues and summarizes the test results for 17 different types of test equipment: ten environmental chambers, two ultralow temperature freezers, two coolant recirculators, one temperature control unit, one vapor degreaser, and one refrigerant recovery system. The postconversion performance test results have been very encouraging: system capacity and input power remained virtually unchanged. In some cases, the minimum operating temperature increased by a few degrees as a result of the conversion, but never beyond AGMC's functional requirements.

Hall, Richard L.; Johnson, Madeleine R.

1995-01-01

222

Thermoelectric refrigerator  

NASA Technical Reports Server (NTRS)

A refrigerator is provided which combines the benefits of superinsulation materials with thermoelectric devices and phase change materials to provide an environmentally benign system that is energy efficient and can maintain relatively uniform temperatures for extended periods of time with relatively low electrical power requirements. The refrigerator includes a thermoelectric assembly having a thermoelectric device with a hot sink and a cold sink. The superinsulation materials include a plurality of vacuum panels. The refrigerator is formed from an enclosed structure having a door. The vacuum panels may be contained within the walls of the enclosed structure and the door. By mounting the thermoelectric assembly on the door, the manufacturer of the enclosed structure is simplified and the overall R rating of the refrigerator increased. Also an electrical motor and propellers may be mounted on the door to assist in the circulation of air to improve the efficiency of the cold sink and the hot sink. A propeller and/or impeller is preferably mounted within the refrigerator to assist in establishing the desired air circulation flow path.

Park, Brian V. (Inventor); Smith, Jr., Malcolm C. (Inventor); McGrath, Ralph D. (Inventor); Gilley, Michael D. (Inventor); Criscuolo, Lance (Inventor); Nelson, John L. (Inventor)

1996-01-01

223

Atmospheric trend and emission estimates for HFC-43-10mee (1999 to 2010)  

NASA Astrophysics Data System (ADS)

We present the first atmospheric measurements of HFC-43-10mee (1,1,1,2,2,3,4,5,5,5-decafluoropentane), an anthropogenic gas introduced in the mid-1990s as a substitute for CFC-113 (1,1,2-trichlorotrifluoroethane). The global warming potential of this HFC (hydrofluorocarbon) has been reported as 1640 (100-year time horizon), hence, its inclusion within a class of chemicals in the Kyoto Protocol and now its consideration for addition in the Montreal Protocol. Commercial HFC-43-10mee is a mixture of two diastereomers; both detectable using the Medusa GC-MS cryogenic trapping system (Miller et al., 2008), and included in our calculations for total HFC-43-10mee concentration. Chen et al. [2010] recently reported that the diastereomers have identical lifetimes in the troposphere of ?18 years. Our northern hemisphere (NH) tropospheric record spans from 1999 to present day, utilizing 12 archive samples together with recent in situ measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) program at Trinidad Head and La Jolla, California. Precisions of < 0.01 ppt (parts-per-trillion, dry air mole fraction) allow for observation of an accelerated rise from 0.04 ppt in 2000 (growth rate of 0.01 ppt/yr) to 0.10 ppt in 2005 (0.02 ppt/yr) and 0.21 ppt in 2010 (0.03 ppt/yr). From the experimentally defined mole fractions in the background NH, we estimate the growth trend in the southern hemisphere using a simple box model which includes the stratosphere. Further, we estimate ‘top-down’ emissions to the global atmosphere for 2009 at ? 1200 tonnes. ‘Bottom-up’ estimates from the Emission Database for Global Atmospheric Research (EDGAR) v.4.0 only include emissions from Austria and France in 2005, which total 206 tonnes. For comparison, the global emissions in 2005 from our model equate to ? 800 tonnes. Further measurement and modeling efforts are warranted together with projections of future consumption. References: Miller, B. R., R. F. Weiss, P. K. Salameh, T. Tanhua, B. R. Greally, J. Mühle, and P. G. Simmonds (2008), Medusa: A sample preconcentration and GC/MS detector system for in situ measurements of atmospheric trace halocarbons, hydrocarbons and sulfur compounds, Anal. Chem., 80, 1536- 1545. Chen, L., S. Uchimaru, K. Kutsuna, K.Tokuhashi and A. Sekiya (2010), Kinetics study of gas-phase reactions of erythro/threo-CF3CHFCHFC2F5 with OH radicals at 253-328 K, Chem. Phys. Lett., 488, 22-26

Arnold, T.; Ivy, D. J.; Muhle, J.; Harth, C. M.; Salameh, P.; Weiss, R. F.

2010-12-01

224

Investigation of flushing and clean-out methods for refrigeration equipment to ensure system compatibility. Quarterly technical progress report, September 15, 1994--December 15, 1994  

SciTech Connect

Integral Sciences Incorporated is engaged in Part 2 of ARTI Contract No. 660-52502 assessing methods for removing residual mineral oil during retrofits of refrigeration systems. Part 2 focuses on a low side oil separator technique for removing mineral oil from systems being retrofitted to use HFC-134a. The method appears less expensive than the current practice of three lubricant changes with polyolester and may effect an accelerated transition to HFC`s. Testing and method verification has been performed using a refrigeration system located at ISI`s facility. Two HFC-134a field retrofits employing this method will be implemented during the first quarter of 1995. A third and final field retrofit will also be performed to evaluate the advanced method in an R-502 conversion.

Byrne, J.J. [Integral Sciences, Inc., Columbus, OH (United States)

1995-07-01

225

Refrigeration Showcases  

NASA Technical Reports Server (NTRS)

Through the Technology Affiliates Program at the Jet Propulsion Laboratory (JPL), valuable modifications were made to refrigerator displays built by Displaymor Manufacturing Company, Inc. By working with JPL, Displaymor could address stiffer requirements that ensure the freshness of foods. The application of the space technology meant that the small business would be able to continue to market its cases without incurring expenses that could threaten the viability of the business, and the future of several dozen jobs. Research and development improvements in air flow distribution and refrigeration coil technology contributed greatly to certifying Displaymor's showcases given the new federal regulations. These modifications resulted in a refrigerator case that will keep foods cooler, longer. Such changes maintained the openness of the display, critical to customer visibility and accessibility, impulse buying, and cross-merchandising.

1997-01-01

226

Viscosity of gaseous HFC-125 (pentafluoroethane) under high pressures  

SciTech Connect

This paper reports experimental results for the viscosity of gaseous HFC-125 (pentafluoroethane) under high pressures. The measurements were carried out with an oscillating-disk viscometer of the Maxwell type at temperatures from 298.15 to 423.15 K and at pressures up to the saturated vapor pressures at each temperature at subcritical conditions or up to 9 MPa at supercritical temperatures. Intermolecular scaling parameters of HFC-125 for the extended corresponding states were determined from the viscosity data at 0.1 MPa. An empirical viscosity equation is proposed to interpolate the present experimental results as a function of temperature and density.

Takahashi, M.; Shibasaki-Kitakawa, N.; Yokoyama, C. [Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science] [Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science

1999-03-01

227

Refrigeration Servicing.  

ERIC Educational Resources Information Center

This self-study course is designed to familiarize Marine enlisted personnel with the services required to be performed on refrigeration equipment. The course contains four study units. Each study unit begins with a general objective, which is a statement of what the student should learn from the unit. The study units are divided into numbered work…

Hamilton, Donald L.; And Others

228

Laboratory evaluation of skin refrigerants used in dermabrasion  

SciTech Connect

Six skin refrigerants were evaluated for maximum cooling temperature. The temperatures produced correlated well with the chemical components and also the gelatin freeze-thaw times. Freon 114 and Freon 114-ethyl chloride mixtures are time-tested, safe skin refrigerants. Some of the newer skin refrigerants are pure sources of Freon 12 or mixtures of Freon 12 and Freon 11. These newer, colder products have the potential to damage the skin and represent a hazard to successful dermabrasion.

Hanke, C.W.; O'Brian, J.J.; Solow, E.B.

1985-01-01

229

Infrared absorption cross-sections and integrated absorption intensities of HFC-134 and HFC-143a vapour.  

NASA Astrophysics Data System (ADS)

Infrared absorption cross-sections and integrated absorption intensities of HFC-134 (1,1,2,2-tetrafluoroethane) and HFC-143a (1,1,1-trifluoroethane) vapour have been determined from laboratory measurements at six temperatures (203, 213, 233, 253, 273 and 297 K) for the region 560-1900 cm-1 (5.3-17.9 ?m) at 0.03 cm-1 instrument resolution, by Fourier transform infrared spectroscopy. In addition, air-broadened spectra have been recorded at 297 K and pressures of 5, 20 and 100 kPa air. Inter-comparisons between this work and previous studies have been made where possible.

Smith, K.; Newnham, D.; Page, M.; Ballard, J.; Duxbury, G.

1998-05-01

230

Alternatives to CFC-114 in high-temperature heat pumps: Compressor performance with HFC-236ea and HFC-236fa  

SciTech Connect

The paper gives results of comprehensive calorimeter tests on a semihermetic compressor with chlorofluorocarbon (CFC)-114, hydrofluorocarbon (HFC)-236ea, and HFC-236fa over a wide range of temperature test conditions: evaporating temperatures from 0 to 35 C and condensing temperatures from 40 to 110 C. Parameters assessed as criteria for performance evaluation and for reliable performance include: cooling capacity; electric power input, current, and voltage; coefficients of performance; compressor volumetric and isentropic efficiencies; and discharge and oil temperatures. Polyolester oil was used as lubricant in the compressor.

Kazachki, G.S.; Gage, C.L.; Hendriks, R.V.

1996-12-31

231

Carbon dioxide emission implications if hydrofluorocarbons are regulated: a refrigeration case study.  

PubMed

The U.S. is strongly considering regulating hydrofluorocarbons (HFCs) due to their global climate change forcing effects. A drop-in replacement hydrofluoroether has been evaluated using a gate-to-grave life cycle assessment of greenhouse gas emissions for the trade-offs between direct and indirect carbon dioxide equivalent emissions compared to a current HFC and a historically used refrigerant. The results indicate current regulations being considered may increase global climate change. PMID:20050659

Blowers, Paul; Lownsbury, James M

2010-03-01

232

Experiment and simulation on the performance of an autocascade refrigeration system using carbon dioxide as a refrigerant  

Microsoft Academic Search

The main purpose of this study is to investigate the performance of an autocascade refrigeration system using zeotropic refrigerant mixtures of R744\\/134a and R744\\/290. One of the advantages of this system is the possibility of keeping the highest pressure of the system within a limit by selecting the composition of a refrigerant mixture as compared to that in the vapor

S. G Kim; M. S Kim

2002-01-01

233

SARPVBR-a VBR rate control algorithm for HFC networks  

Microsoft Academic Search

The paper presents a VBR rate control algorithm for the SARP (simple ATM based reservation protocol) for HFC (hybrid fiber coax) networks. The SARP is a hybrid reservation and rate based protocol, based on ATM, whose main characteristics are its simplicity, high efficiency, and flexibility to support different classes of traffic. SARPVBR tries to match the transmission grant rates given

M. M. Macedo; M. S. Nunes; H. D. Ramos

1997-01-01

234

A study of TCP dynamics over HFC networks  

Microsoft Academic Search

New broadband access technologies such as hybrid fiber coaxial (HFC) are likely to provide fast and cost effective support to a variety of applications including video on demand (VoD), interactive computer games, and Internet-type applications such as Web browsing, FTP, email, and telephony. Since most of these applications, use TCP as the transport layer protocol, the key to their success

Omar Elloumi; Nada Golmie; H. Afifi; David Su

1998-01-01

235

Impulse noise identification for the HFC upstream channel  

Microsoft Academic Search

An algorithm is described that identifies the shape of the impulse within the impulse noise component of the HFC upstream channel. The cross-correlation function (CCF) is used to align samples of the impulse waveforms in time. The singular value decomposition (SVD) finds the dominant basis waveforms that represent the collection of samples. We find that two frequency-modulated basis waveforms sufficiently

Kuo-Hui Li; Arden Huang; Mary Ann Ingram; Daniel Howard

1998-01-01

236

Dynamic bandwidth allocation for the HFC DOCSIS MAC protocol  

Microsoft Academic Search

DOCSIS (Data Over Cable Service Interface Specifications) is the new specification for data transmission over the HFC (hybrid fiber\\/coax) networks. In the DOCSIS media access control (MAC) layer, the headend or CMTS (cable modem termination system) controls transmissions in the upstream direction using a centralized reservation-based approach, and is also responsible for downstream transmissions. We explore mechanisms for delivering quality

Mamdouh Droubi; Nasser Idirene; Charles Chen

2000-01-01

237

46 CFR 151.50-79 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2011 CFR

...acetylene-propadiene mixture must have a refrigeration system that does not compress the cargo vapor or have a refrigeration system with the following features...piping system, including the cargo refrigeration system, for tanks to be...

2011-10-01

238

HFC-6000 for Nuclear I and C Upgrade  

SciTech Connect

The scalability of the HFC-6000 product line makes it an effective solution for nuclear power plant I and C upgrade applications. Its 19-in. rack-mounted platform provides a modular structure whose components can be used for many different nuclear power plant safety applications. This single-platform solution reduces the overall complexity of I and C implementation by minimizing operational and maintenance requirements. The HFC-6000 product line is designed to operate with either single or multiple control remote units in each channel. The main controller module in a remote unit is the system controller (HFCSBC06), which executes control logic programs, I/O scan, and C-Link communication. All three functions are handled by dedicated 64/32-bit microprocessors. A redundant configuration of system controllers consists of two HFC-SBC06 modules and one HFC-DPM06 dual-ported memory module. The hardware interface with external peripheral equipment is provided by an HFC-PCC06 peripheral interface module in the same rack. This module communicates with dedicated Control Switch Modules (the operator interface for digital control) and M/A stations (the operator interface for analog control), which are mounted on the plant main control board. Individual input/output modules serve as the hardware interface with the field devices under control and are implemented by different types of I/O modules. Each I/O module has a redundant serial communication interface. This serial interface employs a proprietary poll-response intercommunication link (ICL) protocol for communication with the system controllers. When a remote is configured with redundant controllers, the two ICL interfaces on each I/O module are connected to separate system controllers to create a redundant link. The I/O modules can be installed locally or remotely. If the I/O modules are physically remote from the controller, the ICL can be implemented with fiber optics to provide physical and electrical isolation from non-safety components. An HFC-FPD06 Flat Panel Display Module can be used as a human-machine interface (HMI). This HMI is composed of a qualified flat panel display and an HFC-FPC06 FPD controller. The FPC06 module has hardware interfaces for both the ICL and the fast Ethernet C-Link. It is configured as a subordinate to the HFC-SBC06 system controller and controls graphic displays on the HMI; it can also perform data voting and validation functions for redundant or triple redundant safety channels. The HFC-FPC06 can be used in either single or redundant configurations. The Power Supply Module consists of a redundant, rack-mounted power supply set. The typical configuration provides 24-vdc for all logic functions and 48-vdc for excitation power. Individual power supplies are redundant and hot swappable. Currently, HFC-6000 system is being installed in Kori Units no.1 to no.4 for its AAC D/G control and monitoring system and several other NPP I and C upgrade projects. (authors)

Taylor, Jonathan; Hsu, Allen; Gerardis, Terry; Stevens, John; McCreary, Tim; Yang, Steve [HF Controls Corporation, 16650 Westgrove Dr., Suite 500s (United States)

2006-07-01

239

Magnetic refrigeration development  

NASA Technical Reports Server (NTRS)

Magnetic refrigeration is being developed to determine whether it may be used as an alternative to the Joule-Thomson circuit of a closed cycle refrigerator for providing 4 K refrigeration. An engineering model 4-15 K magnetic refrigerator has been designed and is being fabricated. This article describes the overall design of the magnetic refrigerator.

Deardoff, D. D.; Johnson, D. L.

1984-01-01

240

Fluorescent refrigeration  

DOEpatents

Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement.

Epstein, Richard I. (Santa Fe, NM) [Santa Fe, NM; Edwards, Bradley C. (Los Alamos, NM) [Los Alamos, NM; Buchwald, Melvin I. (Santa Fe, NM) [Santa Fe, NM; Gosnell, Timothy R. (Santa Fe, NM) [Santa Fe, NM

1995-01-01

241

Refrigerant pressurization system with a two-phase condensing ejector  

DOEpatents

A refrigerant pressurization system including an ejector having a first conduit for flowing a liquid refrigerant therethrough and a nozzle for accelerating a vapor refrigerant therethrough. The first conduit is positioned such that the liquid refrigerant is discharged from the first conduit into the nozzle. The ejector includes a mixing chamber for condensing the vapor refrigerant. The mixing chamber comprises at least a portion of the nozzle and transitions into a second conduit having a substantially constant cross sectional area. The condensation of the vapor refrigerant in the mixing chamber causes the refrigerant mixture in at least a portion of the mixing chamber to be at a pressure greater than that of the refrigerant entering the nozzle and greater than that entering the first conduit.

Bergander, Mark (Madison, CT) [Madison, CT

2009-07-14

242

Stirling Refrigerating Machines — Promising Equipement for Moderate Refrigeration  

Microsoft Academic Search

Data on Stirling refrigerating machines for supermarket refrigerating systems, domestic refrigerators, refrigerating plants, automobile air conditioners, etc., are given. The technical level and experience of Stirling refrigerating machine making in Russia are analyzed.

N. G. Kirillov

2005-01-01

243

Refrigerant directly cooled capacitors  

DOEpatents

The invention is a direct contact refrigerant cooling system using a refrigerant floating loop having a refrigerant and refrigeration devices. The cooling system has at least one hermetic container disposed in the refrigerant floating loop. The hermetic container has at least one electronic component selected from the group consisting of capacitors, power electronic switches and gating signal module. The refrigerant is in direct contact with the electronic component.

Hsu, John S. (Oak Ridge, TN); Seiber, Larry E. (Oak Ridge, TN); Marlino, Laura D. (Oak Ridge, TN); Ayers, Curtis W. (Kingston, TN)

2007-09-11

244

Choked flow mechanism of HFC-134a flowing through short-tube orifices  

SciTech Connect

This paper is a continuation of the author's previous work. New experimental data on the occurrence of choked flow phenomenon and mass flow rate of HFC-134a inside short-tube orifices under choked flow condition are presented. Short-tube orifices diameters ranging from 0.406 mm to 0.686 mm with lengths ranging from 1 mm to 3 mm which can be applied to a miniature vapour-compression refrigeration system are examined. The experimental results indicated that the occurrence of choked flow phenomena inside short-tube orifices is different from that obtained from short-tube orifice diameters of greater than 1 mm, which are typically used in air-conditioner. The beginning of choked flow is dependent on the downstream pressure, degree of subcooling, and length-to-diameter ratio. Under choked flow condition, the mass flow rate is greatly varied with the short-tube orifice dimension, but it is slightly affected by the operating conditions. A correlation of mass flow rate through short-tube orifices is proposed in terms of the dimensionless parameters. The predicted results show good agreement with experimental data with a mean deviation of 4.69%. (author) transfer coefficient was also proposed. (author)

Nilpueng, Kitti; Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab (FUTURE), Department of Mechanical Engineering, King Mongkut's University of Technology Thonburi, Bangmod, Bangkok (Thailand)

2011-02-15

245

A thermodynamic model for ternary mixture systems—Gas blends in a polymer melt  

Microsoft Academic Search

This paper presents a generalized methodology to establish a thermodynamic model that describes a ternary mixture system, which includes a blend of two gases and a polymer melt. The model can be derived based on a phase equilibrium condition and an Equation of State (EOS). As a case study, a model for the ternary system that contains an HFC-134a\\/HFC-152a blend

G. Li; S. N. Leung; M. M. Hasan; J. Wang; C. B. Park; R. Simha

2008-01-01

246

Precipitation of polystyrene by spraying polystyrene-toluene solution into compressed HFC-134a  

SciTech Connect

A precipitation process employing compressed 1,1,1,2-tetrafluoroethane (HFC-134a) as anti-solvent was used to recover polystyrene from toluene solution. In a continuous mode of operation, almost all the dissolved polystyrene could be precipitated under the condition that liquid HFC-134a was present in the precipitator. When the precipitator was full of gaseous HFC-134a only, a significant temperature rise was observed and the amount of the precipitated polystyrene was small. The effects of temperature, pressure, toluene solution flow rate, HFC-134a flow rate, and polystyrene concentration on the yield and morphology for the precipitated polystyrene were examined in this study. Microparticles of the precipitated polystyrene were obtained only when the solution jet traveled through gaseous HFC-134a first and then contacted with liquid HFC-134a in the precipitator.

Tan, C.S.; Lin, H.Y.

1999-10-01

247

Holding Amount of Refrigerant in Refrigeration System.  

National Technical Information Service (NTIS)

The procedure for the prediction of charge amount of refrigerant in refrigerating system is presented. The hold up in two-phase region of evaporator and condenser is determined by adopting Hughmark's correlation, which, compared with Lockhart-Martinelli's...

T. Otaki T. Yoshii

1975-01-01

248

Fluorescent refrigeration  

DOEpatents

Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement. 6 figs.

Epstein, R.I.; Edwards, B.C.; Buchwald, M.I.; Gosnell, T.R.

1995-09-05

249

Phonon Spectra in TaC and HfC  

Microsoft Academic Search

Phonon dispersion curves have been measured by one-phonon coherent inelastic neutron scattering in the high-symmetry directions of TaC at room temperature and at 4.2°K (superconducting transition temperature Tc~10°K). Pronounced structure is observed in the [001] and [110] directions for the longitudinal acoustic modes and, to some extent, for the longitudinal optic modes. By contrast, HfC (Tc<1°K) exhibits little or no

H. G. Smith; W. Gläser

1970-01-01

250

HFC Access Network Design for Switched Broadcast TV Services  

Microsoft Academic Search

The hybrid fiber coax (HFC) is a modern broadband access network, providing advanced interactive services such as Internet access, digital interactive television and cable telephony. The edge costs dominate the cost of launching new services, at the time of deployment (CapEx) as well as for maintenance (OpEx). Therefore next-generation edge devices aim at the convergence of these services and their

Tim Wauters; Jeffrey De Bruyne; Luc Martens; Didier Colle; Bart Dhoedt; Piet Demeester; Kurt Haelvoet

2007-01-01

251

The performance of a triple pressure level absorption cycle (TPLAC) with working fluids based on the absorbent DMEU and the refrigerants R22, R32, R124, R125, R134a and R152a  

Microsoft Academic Search

This paper compares the performance of a single-stage triple pressure level (TPL) absorption cycle with different refrigerant–absorbent pairs. Four HFC refrigerants namely: R32, R125, R134a and R152a which are alternative to HCFC, such as R22 and R124, in combination with the absorbent dimethylethylenurea (DMEU) were considered. The highest coefficient of performance (COP) and the lowest circulation ratio (f), were found

M. Jelinek; A. Levy; I. Borde

2008-01-01

252

Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Three-Year Results with Third-Generation Blowing Agents  

SciTech Connect

Laboratory data are presented on the effect of constant-temperature aging on the apparent thermal conductivity of polyurethane foam insulation for refrigerators and freezers. The foam specimens were blown with HCFC-141b and with three of its potential replacements--HFC-134a, HFC-245fa, and cyclopentane. Specimens were aged at constant temperatures of 90 F, 40 F, and -10 F. Thermal conductivity measurements were made on two types of specimens: full-thickness simulated refrigerator panels containing foam enclosed between solid plastic sheets, and thin slices of core foam cut from similar panels. Results are presented for the first three years of a multi-year aging study. Preliminary comparisons of measured data with predictions of a mathematical aging model are presented.

Wilkes, K.E.

2001-05-29

253

Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--One-Year Results with Third-Generation Blowing Agents  

SciTech Connect

Laboratory data are presented on the effect of constant-temperature aging on the apparent thermal conductivity of polyurethane foam insulation for refrigerators and freezers. The foam specimens were blown with HCFC-141b and with three of its potential replacements--HFC-134a, HFC-245fa, and cyclopentane. Specimens were aged at constant temperatures of 90 F, 40 F, and {minus}10 F. Thermal conductivity measurements were made on two types of specimens: full-thickness simulated refrigerator panels containing foam enclosed between solid plastic sheets, and thin slices of core foam cut from similar panels. Results are presented for the first year of a multi-year study for the full-thickness panels and for about 1-1/2 years of aging for the core-foam specimens.

Gabbard, W.A.; Weaver, F.J.; Wilkes, K.E.

1999-09-27

254

Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels--Two-Year Results with Third-Generation Blowing Agents  

SciTech Connect

Laboratory data are presented on the effect of constant-temperature aging on the apparent thermal conductivity of polyurethane foam insulation for refrigerators and freezers. The foam specimens were blown with HCFC-141b and with three of its potential replacements--HFC-134a, HFC-245fa, and cyclopentane. Specimens were aged at constant temperatures of 90 F, 40 F, and {minus}10 F. Thermal conductivity measurements were made on two types of specimens: full-thickness simulated refrigerator panels containing foam enclosed between solid plastic sheets, and thin slices of core foam cut from similar panels. Results are presented for the first two years of a multi-year aging study. Preliminary comparisons of measured data with predictions of a mathematical aging model are presented.

Wilkes, K.E.

2001-02-14

255

Thermal conductivity of gaseous HFC-134a, HFC-143a, HCFC-141b, and HCFC-142b  

NASA Astrophysics Data System (ADS)

The thermal conductivity of new environmentally acceptable fluorocarbons HFC-134a (CH2FCF3), HFC-143a (CH3CF3), HCFC-141b (CH3CCl2F), and HCFC-142b (CH3CCl2F) in the gaseous phase has been measured in the temperature range 293 353 K at pressures up to 4 MPa. The thermal conductivity has been measured with a coaxial-cylinder cell on a relative basis. The apparatus was calibrated with He, Ne, Ar, Kr, N2, CH4, and SF6 as reference fluids. The uncertainty of the experimental data obtained is estimated to be within 2% except for the uncertainty associated with the reference thermal-conductivity values. The excess thermal conductivity has been correlated satisfactorily as a function of density.

Tanaka, Y.; Nakata, M.; Makita, T.

1991-11-01

256

REACH. Refrigeration Units.  

ERIC Educational Resources Information Center

As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of refrigeration. The instructional units focus on refrigeration fundamentals, tubing and pipe, refrigerants, troubleshooting, window air conditioning, and…

Snow, Rufus; And Others

257

Condensation and single-phase heat transfer coefficient and flow regime visualization in microchannel tubes for HFC-134A  

NASA Astrophysics Data System (ADS)

This dissertation is to document experimental, local condensation and single-phase heat transfer and flow data of the minute diameter, microchannel tube and to develop correlation methods for optimizing the design of horizontal-microchannel condensers. It is essential to collect local data as the condensation progresses through several different flow patterns, since as more liquid is formed, the mechanism conducting heat transfer and flow is also changing. Therefore, the identification of the flow pattern is as important as the thermal and dynamic data. The experimental results were compared with correlation and flow regime maps from literature. The experiment using refrigerant HFC-134a in flat, multi-port aluminum tubing with 1.46mm hydraulic diameter was conducted. The characteristic of single-phase friction can be described with the analytical solution of square channel. The Gnielinski correlation provided good prediction of single-phase turbulent flow heat transfer. Higher mass fluxes and qualities resulted in increased condensation heat transfer and were more effective in the shear-dominated annular flow. The effect of temperature gradient from wall to refrigerant attributed profoundly in the gravity-dominated wavy/slug flow. Two correlation based on different flow mechanisms were developed for specified flow regimes. Finally, an asymptotic correlation was successfully proposed to account for the entire data regardless of flow patterns. Data taken from experiment and observations obtained from flow visualization, resulted in a better understanding of the physics in microchannel condensation, optimized designs in the microchannel condensers are now possible.

Wang, Wei-Wen William

258

Stirling Refrigerator  

NASA Astrophysics Data System (ADS)

A Stirling cooler (refrigerator) was proposed in 1862 and the first Stirling cooler was put on market in 1955. Since then, many Stirling coolers have been developed and marketed as cryocoolers. Recently, Stirling cycle machines for heating and cooling at near-ambient temperatures between 173 and 400K, are recognized as promising candidates for alternative system which are more compatible with people and the Earth. The ideal cycles of Stirling cycle machine offer the highest thermal efficiencies and the working fluids do not cause serious environmental problems of ozone depletion and global warming. In this review, the basic thermodynamics of Stirling cycle are briefly described to quantify the attractive cycle performance. The fundamentals to realize actual Stirling coolers and heat pumps are introduced in detail. The current status of the Stirling cycle machine technologies is reviewed. Some machines have almost achieved the target performance. Also, duplex-Stirling-cycle and Vuilleumier-cycle machines and their performance are introduced.

Kagawa, Noboru

259

Comparable Performance Evaluation of HC and HFC Refrigerants in an Optimized System.  

National Technical Information Service (NTIS)

This paper presents an analytical evaluation of isobutane (R600a), propane (R290), R134a, R22, R410A, and R32 in a vapor compression system used for comfort cooling applications. The evaluation method was based on a system simulation model that was compli...

D. Yashar P. A. Domanski

2006-01-01

260

DOCSIS performance analysis under high traffic conditions in the HFC networks  

Microsoft Academic Search

Hybrid Fiber Coaxial (HFC) networks provide a wide bandwidth and represent the solution of choice for many residential networks nowadays. The Data Over Cable Service Interface Specification (DOCSIS) protocol is an important standard for HFC networks and is supported by the majority of current vendors. This protocol uses the Truncated Binary Exponential Back-off (TBEB) algorithm to resolve collisions within the

Wei-Tsong Lee; Kun-Chen Chung; Kuo-Chih Chu; Jen-Yi Pan

2006-01-01

261

EVALUATION OF HFC-245FA AS A POTENTIAL ALTERNATIVE FOR CFC-11 IN LOW PRESSURE CHILLERS  

EPA Science Inventory

The paper reports results of an evaluation of HFC-245fa as a potential alternative for CFC-11 in low pressure chillers. (NOTE: It was reported previously that HFC245ca (1,1,2,2,3-pentafluoro-propane) has many attributes that make it an attractive candidate alternative for CFC-11 ...

262

FURTHER DEVELOPMENT OF A MIXED GAS JOULE THOMSON REFRIGERATOR  

Microsoft Academic Search

A mixed gas Joule Thomson refrigerator has distinct advantages over other cryocooler for certain applications. The system is compact, has good thermodynamic efficiency and low levels of vibration and noise. Further development of this refrigeration machine is possible by optimization of the gas mixture composition. A method was developed which permits a reduction by a large factor in the number

A. Alexeev; Ch. Haberstroh; H. Quack

263

Adsorption of hydrofluorocarbons HFC-134 and HFC-134A on X and Y zeolites: Effect of ion-exchange on selectivity and heat of adsorption  

SciTech Connect

Adsorption isotherms and heats of adsorption were measured for HFC-134 (1,1,2,2-tetrafluoroethane) and HFC-134a (1,1,1,2-tetrafluoroethane) on a series of ion-exchanged (H, Li, Na, Rb, Cs) faujasites using volumetric and calorimetric techniques. The species and number of ions present in the zeolite strongly influence the heats of adsorption and the preferential adsorption of HFC-134 compared to HFC-134a. The selectivity is considerably higher in X than in Y zeolites because of the larger number of nonframework ions in X zeolites. The saturation capacity is six molecules per supercavity for both HFCs. The differences in observed heats of adsorption (except for RbX) can be explained by reasonable and consistent values of dispersion and ion-dipole electrostatic energies. The high selectivities for NaX and RbX indicate that either zeolite would be highly effective for gas separation.

Savitz, S.; Siperstein, F.R.; Huber, R.; Tieri, S.M.; Gorte, R.J.; Myers, A.L.; Grey, C.P.; Corbin, D.R.

1999-09-30

264

Liquid-air partition coefficients of 1,1-difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFC143a), 1,1,1,2-tetrafluoroethane (HFC134a), 1,1,1,2,2-pentafluoroethane (HFC125) and 1,1,1,3,3-pentafluoropropane (HFC245fa).  

PubMed

Blood-air and tissue-blood coefficients (lambda) are essential to characterize the uptake and disposition of volatile substances, e.g. by physiologically based pharmacokinetic (PBPK) modelling. Highly volatile chemicals, including many hydrofluorocarbons (HFC) have low solubility in liquid media. These characteristics pose challenges for determining lambda values. A modified head-space vial equilibrium method was used to determine lambda values for five widely used HFCs. The method is based on automated head-space gas chromatography and injection of equal amount of chemical in two head-space vials with identical air phase volumes but different volumes of the liquid phase. The liquids used were water (physiological saline), fresh human blood, and olive oil. The average lambda values (n = 8) were as follows: 1,1-difluoroethane (HFC152a) - 1.08 (blood-air), 1.11 (water-air) and 5.6 (oil-air); 1,1,1-trifluoroethane (HFC143a) - 0.15, 0.15 and 1.90; 1,1,1,2-tetrafluoroethane (HFC134a) - 0.36, 0.35 and 3.5; 1,1,1,2,2-pentafluoroethane (HFC125) - 0.083, 0.074 and 1.71; and 1,1,1,3,3-pentafluoropropane (HFC245fa) - 0.62, 0.58 and 12.1. The lambda values appeared to be concentration-independent in the investigated range (2-200 ppm). In spite of the low lambda values, the method errors were modest, with coefficients of variation of 9, 11 and 10% for water, blood and oil, respectively. PMID:19701883

Ernstgård, Lena; Lind, Birger; Andersen, Melvin E; Johanson, Gunnar

2010-01-01

265

Refrigeration for Cryogenic Sensors  

NASA Astrophysics Data System (ADS)

Research in cryogenically cooled refrigerators is discussed. Low-power Stirling cryocoolers; spacecraft-borne long-life units; heat exchangers; performance tests; split-stirling, linear-resonant, cryogenic refrigerators; and computer models are among the topics discussed.

Gasser, M. G.

1983-12-01

266

New Rules for Refrigerants.  

ERIC Educational Resources Information Center

Discusses how educational facilities can comply with new Environmental Protection Agency regulations regarding commercial refrigerants. Tips include developing a compliance plan with a manager in charge of it, and developing an accurate and complete refrigerant-systems assessment. (GR)

Jackson, Robert

1999-01-01

267

Refrigeration for Cryogenic Sensors  

NASA Technical Reports Server (NTRS)

Research in cryogenically cooled refrigerators is discussed. Low-power Stirling cryocoolers; spacecraft-borne long-life units; heat exchangers; performance tests; split-stirling, linear-resonant, cryogenic refrigerators; and computer models are among the topics discussed.

Gasser, M. G. (editor)

1983-01-01

268

Superfluid Joule–Thomson Refrigeration, a New Concept for Cooling Below 2 Kelvin  

Microsoft Academic Search

A new type of sub-Kelvin refrigerator, the superfluid Joule–Thomson refrigerator is discussed. The refrigerator uses the circulation of the 3He component of a liquid 3He–4He mixture through a throttle to provide cooling to temperatures of 0.5 K. A simple analytical model is developed to predict the cooling power for this refrigerator as function of temperature. In addition, cooling power predictions

J. G. Brisson

2000-01-01

269

The Experimental Evaluation of a Proof of Principle Superfluid Joule-Thomson Refrigerator  

NASA Astrophysics Data System (ADS)

The performance of a new type of sub-Kelvin refrigerator, the superfluid Joule-Thomson refrigerator, has been experimentally verified. This refrigerator uses a liquid superfluid mixture of 3He and 4He as the working fluid and depends on the non-ideal-gas-like behavior of the 3He component in this mixture to provide cooling when one component of the mixture is passed through a throttle. The refrigerator achieved an ultimate low temperature of 0.68 K when operating with a 3% 3He mixture. When operating with a 5% mixture the cooling power above 0.73 K was greater than with a 3% mixture but the ultimate low temperature was higher (0.71 K). The effect of 3He concentration of the working fluid on the performance of the refrigerator is discussed.

Miller, F. K.; Brisson, J. G.

2006-04-01

270

Molecular modeling of fluoropropene refrigerants.  

PubMed

Different fluoropropenes are currently considered as refrigerants, either as pure compounds or as components in low GWP (global warming potential) refrigerant mixtures. Due to their limited commercial production, experimental data for the thermophysical properties of fluoropropenes and their mixtures are in general rare, which hampers the exploration of their performance in technical applications. In principle, molecular simulation can be used to predict the relevant properties of refrigerants and refrigerant blends, provided that adequate intermolecular potential functions ("force fields") are available. In our earlier work (Raabe, G.; Maginn, E. J., J. Phys. Chem. B2010, 114, 10133-10142), we introduced a transferable force field for fluoropropenes comprising the compounds 3,3,3-trifluoro-1-propene (HFO-1243zf), 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), and hexafluoro-1-propene (HFO-1216). In this paper, we provide an extension of the force field model to the trans- and cis-1,3,3,3-tetrafluoro-1-propene (HFO-1234ze(E), HFO-1234ze) and the cis-1,2,3,3,3-pentafluoro-1-propene (HFO-1225ye(Z)) as well as revised simulation results for HFO-1216. We present Gibbs ensemble simulation results on the vapor pressures, saturated densities, and heats of vaporization of these compounds in comparison with experimental results. The simulation results show that the force field model enables reliable predictions of the properties of the different fluoropropenes and also reproduces well the differing vapor-liquid coexistence and vapor pressure curve of the cis- and trans-isomers of 1,3,3,3-tetrafluoro-1-propene, HFO-1234ze and HFO-1234ze(E). For these two isomers, we also present molecular dynamics simulation studies on their local structure. PMID:22519953

Raabe, Gabriele

2012-05-17

271

Development of Magnetic Refrigerator  

NASA Astrophysics Data System (ADS)

A series of R & D of magnetic refrigerators has been done in order to realize an advanced type cryocooler for superconducting magnets of maglev trains and MRI medical system. As a result of efforts on both the magnetic refrigerator and superconducting magnets, a parasitic type magnetic refrigeration system was proposed.

Ogiwara, Hiroyasu; Nakagome, Hideki; Kuriyama, Tohru

272

Measurement of viscosity, density, and gas solubility of refrigerant blends in selected synthetic lubricants. Quarterly report, October 1--December 30, 1993  

SciTech Connect

Liquid/liquid miscibilities of four different 32 ISO VG polyolesters and one alkylbenzene at three concentrations have been determined with five refrigerant blends, including HC-290. A vapor lubricant equilibrium (VLE) viscosity reduction of 32 ISO VG mineral oil with HCFC-22 has been completed. Composite viscosity reduction information by the fractionate components from R-502 in 32 ISO VG mineral oil has been obtained from {minus}10{degree}C (14{degree}F) to 125{degree}C (257{degree}F) isotherms. Vapor lubricant equilibrium (VLE) viscosity reduction for 32 ISO VG mixed acid polyolester with HFC-134a and HFC-143a has also been completed. Data is also presented for the viscosity reduction of 32 ISO VG branched acid polyolester by these same refrigerants.

Cavestri, R.C.

1994-01-01

273

Docmentation of newly developed methods to assess material compatibility in refrigeration and air-conditioning applications. Final report, 1 October 1993--31 August 1994  

SciTech Connect

This document summarizes the experimental methods used during the materials compatibility and lubricants research program (MCLR). The MCLR program was jointly sponsored by the U.S. Department of Energy and the air-conditioning and refrigeration industry. The individual projects were managed by the Air-Conditioning and Refrigeration Technology Institute. The projects presented in this report are: Chemical and Thermal Stability of Refrigerant/Lubricant Mixtures with Metals, Miscibility of Lubricants with Refrigerants, Compatibility of Refrigerants and Lubricants with Motor Materials, Compatibility of Refrigerants and Lubricants with Elastomers, Compatibility of Refrigerants and Lubricants with Engineering Plastics and Sealed Tube Comparisons of the Compatibility of Desiccants with Refrigerants and Lubricants.

Hawley, M.

1994-08-01

274

Alternate refrigerants and lubricants for the microclimate cooling system. Final report, December 1991-March 1992  

SciTech Connect

This research identified, explored, and evaluated the use of alternative refrigerants and lubricants in vapor compression cycle for refrigeration. With impending phaseouts of chlorofluorocarbons (CFC`s), there is an immediate need to find suitable replacements for use existing systems, as well as new systems designed to operate with the new substances. The alternative refrigerants and lubricants have certain problems when used in retrofitted systems. Differences in properties must also be considered when designing a system for use with the alternatives. For Microclimate Cooling Systems, HFC-134a is considered when designing a system for use with the alternatives. For Microclimate Cooling Systems, HFC-134A is considered to be the best candidate. R-134a requires a higher pressure increase to achieve a good refigeration cycle; however, 134a necessities the use of a new lubricant. For 134a, a polyolester lubricant is the best choice. It has desirable properties and a very low ecotoxicity rating. It is also compatible with CFC-12. This allows a system run with an ester based lubricant and R-12 to be easily retrofitted to operate on 134.

Wolfson, M.W.

1992-09-01

275

Determining rate of refrigerant emissions from nonprofessional automotive service through a southern California field study  

NASA Astrophysics Data System (ADS)

Vehicle owners in the United States can recharge their vehicles' air conditioning systems with small containers of hydrofluorocarbon-134a (HFC-134a, CH2FCF3). This refrigerant, with a Global Warming Potential of 1430, may be emitted to the atmosphere during the recharging operation and from the residual heel in partially used containers, contributing to climate change. A field study was conducted in southern California to quantify the rate of refrigerant emissions from nonprofessional recharging practices and identify emission mitigation opportunities. Based on the results of the study, an average of 489 g of HFC-134a is used when recharging the sample vehicles with an average nominal charge of 858 g. An average 67% of the container content is effectively charged into the systems, 11% of the refrigerant is released during service, and the remaining 22% is left in the containers after operations are completed. A comparison with two other independent studies indicates that the findings of the current study may be applicable not only to southern California, but also to the entire U.S.

Zhan, Tao; Clodic, Denis; Palandre, Lionel; Trémoulet, Arnaud; Riachi, Youssef

2013-11-01

276

Chirped-Pulse Fourier Transform Microwave Spectrum of the Low Global Warming Potential Refrigerant Alternative, 2,3,3,3-TETRAFLUOROPROPENE  

Microsoft Academic Search

A newly-constructed, chirped-pulse Fourier transform microwave spectrometer is used to obtain the microwave spectrum of 2,3,3,3-tetrafluoropropene, which has been proposed as an alternative to HFC-134a for use as a mobile air conditioning refrigerant. With a bandwidth of 6 GHz, this instrument has the potential to provide complete coverage of the microwave spectrum from 6 to 18 GHz in two steps,

Mark D. Marshall; Helen O. Leung; John S. Muenter

2010-01-01

277

Refrigerant Leakage Detection and Diagnosis for a Distributed Refrigeration System  

Microsoft Academic Search

A new technique to detect and diagnose leakage in a distributed refrigeration system is proposed in this paper. Unlike a simple refrigeration system of an HVAC system, a distributed refrigeration system, such as the refrigeration system in a supermarket, consists of several racks of compressors and evaporators, large condenser systems on the roof, meters of refrigerant piping systems, and liquid

Kriengkrai Assawamartbunlue; Michael J. Brandemuehl

2006-01-01

278

Characteristics of a Mixed Refrigerant Vapor Compression Cycle  

NASA Astrophysics Data System (ADS)

In comparison with conventional refrigerants, the use of non-azeotropic binary mixtures of refrigerants in vapor compression refrigerating systems can result in extension of the application limits, higher reliability, and savings in power consumption. This paper discusses the high temperature heat pump system performance operating with mixed refrigerants. In order to survey the system performances with various mixtures, six kinds of mixtures are examined : R22-R1l4, R22-R11, R12-R114, R12-R11, R 12-R113, and R22-R12. Thermodynamic properties of the first five mixtures are calculated from the Peng-Robinson equation of state with the mixing rules proposed by Ototake, and R22-R12 mixtures by the BWR type equation of state proposed by Kagawa et al. When counter-flow heat exchangers with large surface areas are used for the evaporator and the condenser, the temperature differences between the refrigerant and the heat sink / source fluids can be reduced, and so the energy waste resulting from irreversible heat trasfer can be reduced. Comparing the mixed refrigerants with the pure ones by fixing the refrigerant temperature at the evaporator inlet and the dewpoint temperature at the condenser, higher coefficients of performance (COP), lower condensing pressures, and lower pressure ratios in the refrigerant compressor can be realized. But the performances of the mixtures with R114 as a less volatile component are not so good. When the heat transfer surface area is not large, the mean temperature difference becomes large. If the dewpoint temperatures at the evaporator and the condenser fixed, the range of composition for the improvement of the COP is restricted.

Hihara, Eiji; Muneta, Yoshihiro; Saito, Takamoto

279

ARTI refrigerant database  

SciTech Connect

The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on refrigerants. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates. Citations in this report are divided into the following topics: thermophysical properties; materials compatibility; lubricants and tribology; application data; safety; test and analysis methods; impacts; regulatory actions; substitute refrigerants; identification; absorption and adsorption; research programs; and miscellaneous documents. Information is also presented on ordering instructions for the computerized version.

Calm, J.M. [Calm (James M.), Great Falls, VA (United States)] [Calm (James M.), Great Falls, VA (United States)

1996-04-15

280

Monitoring refrigeration energy useage.  

SciTech Connect

Refrigerators use more energy than any other kitchen appliance -- an unsurprising fact considering that refrigerators operate 24 hours a day, 365 days a year to keep food at a safe temperature. In many low-income households, refrigerators eat up more than half the electricity consumed in one year. And if the refrigerator in a family's home is functioning poorly, the cost to the consumer can be enormous. Discovering whether an existing refrigerator is operating inefficiently enough to warrant replacing it is an extremely difficult task for a resident who sees only a monthly electric bill. Only by knowing the approximate usage of the existing unit can anyone tell whether it would pay to buy a new, energy-efficient refrigerator. The savings from replacing older refrigerators can be substantial, and collecting the data needed to determine when refrigerators should be replaced is easier and less costly than one might think. In both Chicago and New York City, replacing existing units cut refrigerator electricity usage by more than 50%. Monitoring to develop an average usage for the existing stock of refrigerators is a task that can be completed by maintenance staff in a reasonably short time -- and identifying poorly performing units that should be immediately replaced can take just two hours of monitoring.

Cavallo, J.; Mapp, J.; Energy Systems; Wisconsin Energy Bureau

2000-05-01

281

trans-1,2Dichloroethylene as an Additive for HFC134a Foam Systems  

Microsoft Academic Search

HFC-134a has been used as a zero ozone depletion potential (ODP) alternative for HCFC-141b in polyurethane foam applications. Between two major categories of zero ODP alternatives, hydrocarbons and HFCs, HFC-134a offers some advantages. It is nonflammable, widely available, and it is less expensive than other HFCs. It is an ideal choice for foam applications where nonflammability, volatile organic compounds (VOCs),

Jinhuang Wu; Chris Bertelo; Vincent Enaux

2005-01-01

282

An Investigation into HFC MAC Protocols: Mechanisms, Implementation, and Research Issues  

Microsoft Academic Search

This study comprehensively reviews two HFC MAC protocols: Data-Over-Cable Service Inter-face Specifications (DOCSIS) and IEEE 802.14a. DOCSIS was approved by the ITU as a stan-dard and is supported by many vendors. However, IEEE 802.14a remains a draft due to the delayed standardization process. After briefly introducing the features of HFC networks, the basic operations and mechanisms of these two MAC

Ying-dar Jason Lin; Wei-ming Yin; Chen-yu Huang

2000-01-01

283

On Quality of Service in an ATM-based HFC Architecture  

Microsoft Academic Search

This paper discusses the Hybrid Fiber-Coaxial cable TV environment as a data delivery serviceproviding subscribers with specific levels of service. We overview HFC for data delivery andCom21's UPSTREAMS architecture for HFC data delivery using an ATM cell based format. Weaddress providing quality of service over this shared medium at three basic levels: constant bit rate(CBR), a guaranteed rate class we

Kathleen M. Nichols; Mark Laubach

1996-01-01

284

Experimental evaluation of HCFC22 replacement by the drop-in fluids HFC422A and HFC417B for low temperature refrigeration applications  

Microsoft Academic Search

The Regulation CE-1005\\/2009 has banned the use of virgin HCFC-22 in Europe from the 31st December 2009, because it contains chlorine, although its use is allowed up to the 31st December 2014 if it is recycled. Now, manufacturers are developing different free-chlorine drop-in solutions to replace the HCFC-22 in the existing equipment by non-ozone depleting substances in order to exhaust

R. Llopis; R. Cabello; D. Sánchez; E. Torrella; J. Patiño; J. G. Sánchez

2011-01-01

285

Recent increases in global HFC-23 emissions and early trends in other HFCs  

NASA Astrophysics Data System (ADS)

Hydrofluorocarbons (HFCs) generally have high global warming potentials and are used as substitutes for ozone-depleting gases. Trifluoromethane (HFC-23) is an unintended by-product of chlorodifluoromethane (HCFC-22) production and has the longest lifetime (270 yr) and largest 100-yr global warming potential (14,800) of all the most commonly produced HFCs. Firn-air and ambient air measurements of HFC-23 from three firn sampling excursions to Antarctica between 2001 and 2009 are used to construct a consistent atmospheric history for this chemical in the Southern Hemisphere. The results show continued increases in the atmospheric abundance of HFC-23 and they imply substantial increases in HFC-23 global emissions since 2003. The increases in HFC-23 emissions are coincident with rapidly increasing HCFC-22 production in developing countries and are observed despite efforts in recent years to limit emissions of HFC-23 through the Kyoto Protocol's Clean Development Mechanism. These results will be considered along with new observations of additional HFCs from archived air, firn air, and ongoing flask-air measurements. Summed together, atmospheric increases observed for HCFCs and HFCs accounted for ~9% of the increase in total direct radiative forcing from anthropogenic gases during 2003-2008, an addition that was slightly larger than that attributable to N2O global mixing ratio increases over this same period.

Montzka, Steve; Kuijpers, Lambert; Miller, Lloyd; Battle, Mark; Aydin, Murat; Verhulst, Kristal; Saltzman, Eric; Fahey, David; Miller, Ben; Hall, Bradley

2010-05-01

286

Solar absorption refrigeration  

SciTech Connect

This patent describes an improvement in an apparatus for producing refrigeration by an intermittent absorption cycle apparatus comprised of a generator/absorber, a condenser, and an evaporator. It comprises: a second absorber which is cooled by refrigeration produced by the evaporator; a second evaporator in which liquid refrigerant is evaporated; a means for routing evaporated refrigerant from the second evaporator to the second absorber; a means for transferring absorbent from the generator/absorber to the second absorber; a reservoir of liquid refrigerant for the second evaporator which is not supply liquid to the evaporator; a means for reducing the pressure of the liquid refrigerant supplied from the reservoir to the second evaporator; and, at least one mans for supplying heat to the generator/absorber comprised of a solar radiation collecting apparatus.

Erickson, D.C.

1990-10-30

287

Refrigerator Based on Chemisorption  

NASA Technical Reports Server (NTRS)

Reversible chemical reaction generates pressurized oxygen for cooling. Concept for cryogenic refrigerator based on chemical absorption of oxygen by praseodymium/cerium oxide (PCO) compound. Refrigerator produces cryogenic liquid for cooling infrared sensors. Also used for liquefying air and separating oxygen from nitrogen in air. In chemisorption refrigerator, PCO alternately absorbs and desorbs oxygen depending on whether cooled or heated. One pair of compressors accepts oxygen while others releases it. Compressed oxygen liquefied when precooked and expanded.

Jones, Jack A.

1987-01-01

288

Refrigerator recycling and CFCs  

Microsoft Academic Search

Utility-sponsored refrigerator and freezer pick-up programs have removed almost 900,000 inefficient appliances from the North American electric grid to date. While the CFC-12 refrigerant from the discarded appliances is typically removed and recycled, in all but a few programs the CFC-11 in the foam insulation is not. About a quarter-billion pounds of CFC-11 are banked in refrigerator foam in the

M. Shepard; W. Hawthorne; A. Wilson

1994-01-01

289

ARTI refrigerant database  

SciTech Connect

The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufactures and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on many refrigerants including propane, ammonia, water, carbon dioxide, propylene, ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

Calm, J.M. [Calm (James M.), Great Falls, VA (United States)] [Calm (James M.), Great Falls, VA (United States)

1998-08-01

290

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator. 5 figs.

Vobach, A.R.

1987-06-23

291

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

Vobach, Arnold R. (6006 Allentown Dr., Spring, TX 77389)

1987-01-01

292

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer (11) at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer (11) to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator (10) to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing he evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator.

Vobach, Arnold R. (6006 Allentown Dr., Spring, TX 77379)

1987-01-01

293

Chemically assisted mechanical refrigeration process  

DOEpatents

There is provided a chemically assisted mechanical refrigeration process including the steps of: mechanically compressing a refrigerant stream which includes vaporized refrigerant; contacting the refrigerant with a solvent in a mixer at a pressure sufficient to promote substantial dissolving of the refrigerant in the solvent in the mixer to form a refrigerant-solvent solution while concurrently placing the solution in heat exchange relation with a working medium to transfer energy to the working medium, said refrigerant-solvent solution exhibiting a negative deviation from Raoult's Law; reducing the pressure over the refrigerant-solvent solution in an evaporator to allow the refrigerant to vaporize and substantially separate from the solvent while concurrently placing the evolving refrigerant-solvent solution in heat exchange relation with a working medium to remove energy from the working medium to thereby form a refrigerant stream and a solvent stream; and passing the solvent and refrigerant stream from the evaporator. 5 figs.

Vobach, A.R.

1987-11-24

294

Selection of the most suitable refrigerant for a shell and tube condenser  

NASA Astrophysics Data System (ADS)

A theoretical performance study on a shell and tube condenser with various refrigerant blends was conducted for various ratios proposed by other researchers in the literature. The theoretical results showed that all of the alternative refrigerants investigated in the analysis have a slightly lower convective heat transfer coefficient than their base refrigerants. The refrigerant mixture of R290/R600, R152a/R125/R32 and R32/R134a were found to be the most proper replacement refrigerant among the alternatives.

Dalkilic, A. S.; Mahian, O.; Wongwises, S.

2014-02-01

295

Optimal synthesis of refrigeration cycles and selection of refrigerants  

SciTech Connect

The optimal synthesis of the refrigeration configuration and the selection of the best refrigerants that satisfy a set of process cooling duties at different temperatures is addressed. This approach simultaneously selects refrigerants and synthesizes refrigeration structures by minimizing a weighted sum of investment and operating costs. A superstructure representation considers the majority of refrigeration cycle features encountered in real complex multistage refrigeration cycles such as economizers, multiple refrigerants, and heat integration. A novel theoretical treatment of modeling representations and algorithmic improvements is introduced. Results, for example, involving multiple refrigerants, cooling loads, and heat sinks are obtained. Complex, nonintuitive topologies typically emerge as the optimal refrigeration configurations that are better than those obtained when refrigeration synthesis is performed after refrigerant selection.

Vaidyaraman, S.; Maranas, C.D. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering] [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering

1999-05-01

296

HFC-134a Emissions in China: An Inventory for 1995-2030  

NASA Astrophysics Data System (ADS)

HFC-134a is the most important substitute of CFC-12 used in the mobile air-conditioner in China since 1995. The bottom-up method was used to estimate HFC-134a emissions in China, from 1995 to 2030, basing on updated automobile industry data and latest emission characters. From 1995, total HFC-134a emission has kept a high growth rate of nearly 60% per year, and reached 16,414.3 Mg (11,959.4-20,834.5 Mg) in 2010, which was equivalent to 23.5 Mt CO2-eq emissions. Furthermore, the emissions in China accounted for nearly half of total emissions of Non-AnnexI countries in 2008. As for provincial emissions in 2010, provinces with emission greater than 1,000 Mg are Guangdong, Shandong, Jiangsu and Beijing. Quantitative relationship between provincial HFC-134a emissions and GRP of the Tertiary Industry was used to estimate HFC-134a emissions at county level, and Hangzhou municipal district held the maximum emission intensity (4,605 Mg/10,000 km2). For HFC-134a, emissions calculated from the observations within 46 cities through Euler box model are in good agreement with the corresponding emissions estimated from the bottom-up method, verifying that the emission inventory at county level adequately describes the emission spatial pattern. For the future emissions of HFC-134a, projected emissions will reach 89,370.4 Mg (65,959.7- 114,068.2 Mg) in 2030 under the Business-as-usual (BAU) Scenario, but under the Alternative Scenario, a emission reduction potential of 88.6% of the projected BAU emissions would be obtained.

Su, Shenshen; Fang, Xuekun; Wu, Jing; Li, Li; Hu, Jianxin; Han, Jiarui

2014-05-01

297

An evaluation on the environmental consequences of residual CFCs from obsolete household refrigerators in China.  

PubMed

Chlorofluorocarbons (CFCs) contained in household refrigerators consist mainly of CFC-11 and CFC-12, which will be eventually released into the environment. Consequentially, environmental releases of these refrigerants will lead to ozone depletion and contribute significantly to the greenhouse effect, if waste refrigerators are not disposed of properly. In the present paper, the potential release of residual CFCs and their substitutes from obsolete household refrigerators in China is examined, and their contributions to ozone depletion and greenhouse effect are compared with those of other recognized ozone-depleting substances (ODS) and greenhouse gases (GHGs). The results imply that annual potential amounts of released residual CFC-11 and CFC-12 will reach their maximums at 4600 and 2300 tons, respectively in 2011, and then decrease gradually to zero until 2020. Meanwhile, the amounts of their most widely used substitutes HCFC-141b and HFC-134a will keep increasing. Subsequently, the contribution ratio of these CFCs and their substitutes to ozone depletion will remain at 25% through 2011, and reach its peak value of 34% by 2018. The contribution to greenhouse effect will reach its peak value of 0.57% by 2010. Moreover, the contribution ratio of these CFCs to the total global release of CFCs will steadily increase, reaching its peak of 15% by 2018. Thus, this period from 2010 to 2018 is a crucial time during which residual CFCs and their substitutes from obsolete household refrigerators in China will contribute significantly to ozone depletion. PMID:21093246

Zhao, Xiangyang; Duan, Huabo; Li, Jinhui

2011-03-01

298

Thermoacoustic engines and refrigerators  

NASA Astrophysics Data System (ADS)

Thermoacoustic engines and refrigerators use gas inertia and compressibility to eliminate many of the mechanical contrivances required by traditional engines and refrigerators while providing potentially attractive options that might reduce environmental impacts. The operation of both standing-wave and traveling-wave devices will be described and illustrated with thermoacoustic devices that have been used outside the laboratory.

Garrett, Steven L.

2012-06-01

299

The smart medical refrigerator  

Microsoft Academic Search

This work presents a smart medical refrigerator. The method suggests to monitor the elderly patients continued usage of medications on time. So a smart medical dispenser is used. The smart medical refrigerator monitors the use of prescribed medicine by patients and can alert a physician, healthcare provider or family members if the patient does not access the medicine in a

P. Kuwik; T. Largi; M. York; D. Crump; D. Livingston; J. C. Squire

2005-01-01

300

Refrigeration for superconductors  

Microsoft Academic Search

Temperatures in the range of 0.05 to 80 K are required for most applications of superconductors. Refrigeration powers range from fractions of a watt for many electronic applications to kilowatts for some large magnet and power applications. This paper reviews the various types of refrigeration methods currently available to meet the needs of various applications of superconductors. The methods covered

R. Radenbaugh

2004-01-01

301

Solar sorption refrigerator  

Microsoft Academic Search

The performance of a solar sorption refrigerator is studied experimentally for three configurations of its collector cover: with single glazing, with double glazing and with single glazing plus transparent insulation. The collector consists of fifteen stainless steel tubes having a selective surface (with good thermal absorption coefficient) and contains granular activated carbon adsorbent with ammonia refrigerant. The collector surface area

E. Munyebvu

1997-01-01

302

Solar thermoelectric refrigerator  

Microsoft Academic Search

It is shown that a thermoelectric generator, which draws its heat from the sun, is a particularly suitable source of electrical power for the operation of a thermoelectric refrigerator. The theory of the combined thermoelectric generator and refrigerator is derived and the ratio of the numbers of thermocouples needed for the two devices is determined. It is found that this

G. J. Vella; L. B. Harris; H. J. Goldsmid

1976-01-01

303

Refrigerant leak detector  

NASA Technical Reports Server (NTRS)

Quantitative leak detector visually demonstrates refrigerant loss from precision volume of large refrigeration system over established period of time from single test point. Mechanical unit is less costly than electronic "sniffers" and is more reliable due to absence of electronic circuits that are susceptible to drift.

Byrne, E. J.

1979-01-01

304

Solar refrigeration utilizing zeolites  

Microsoft Academic Search

Zeolites offer a unique opportunity for a solid-gas adsorption refrigeration system because of their unusual sorption properties, in particular, extremely nonlinear adsorption isotherms. The operating principle of the zeolite system and experimental results are presented. The study demonstrates a zeolite system capable of providing refrigeration and ice production with very good engineering efficiency. This system utilizes natural zeolites as the

D. I. Tchernev

1979-01-01

305

Solar energy refrigeration device  

Microsoft Academic Search

The invention relates to a refrigeration device using solar energy. This device includes a refrigeration fluid, such as water, which circulates between the solar energy heat exchanger containing zeolite, and an evaporator located in a cooling chamber through a condenser, then return to the exchanger through a three way valve. The device includes a second channel in the exchanger, which

A. Wiart; G. Paeye

1985-01-01

306

Joule Thomson refrigerator  

Microsoft Academic Search

A bi-directional Joule Thomson refrigerator is described, which is of simple construction at the cold end of the refrigerator. Compressed gas flowing in either direction through the Joule Thomson expander valve and becoming liquid, is captured in a container in direct continuous contact with the heat load. The Joule Thomson valve is responsive to the temperature of the working fluid

Chung K. Chan; John R. Gatewood

1988-01-01

307

Rotary two-phase refrigeration apparatus and method  

SciTech Connect

Rotary vacuum evaporation of a primary refrigerant cools a secondary refrigerant mixed with it. The secondary refrigerant does not change state and meanders through a low pressure cooling circuit for refrigeration applications. The primary refrigerant changes state and remains in a short and secure circuit. Evaporation is produced at a surface around the axis of rotation and within the mixture by opposed centrifugal and centripetal forces acting through a narrow afferent mesial passage between rotating disks mounted on a hollow shaft. Vapor is stripped from the surface, scrubbed by cyclonic flow through the afferent mesial passage, and condensed by a centrifugal compressor, which is a centrifugal pump having its inlet communicating with the bore of the hollow shaft and the afferent mesial passage. Latent heat is drawn off by water, making this a water heater, and the water is produced by de-humidification. The primary refrigerant and the secondary refrigerant are cheap and environmentally harmless, e.g. propylene glycol and acetone. A method and apparatus for refrigeration using only water is disclosed. Energy efficiency is maximized by avoidance of positive displacement pumps and narrow conduits, and by operation during times when excess power is in the grid. 7 figs.

McCutchen, W.H.

1994-01-04

308

Recent increases in trifluoromethane (HFC-23) global emissions and early atmospheric changes observed for other hydrofluorocarbons  

NASA Astrophysics Data System (ADS)

Trifluoromethane (HFC-23) is an unintended by-product of chlorodifluoromethane (HCFC-22) production and has a 100-yr global warming potential of 14,800. Firn-air and ambient air measurements of HFC-23 from three firn sampling excursions to Antarctica between 2001 and 2009 are used to construct a consistent atmospheric history for this chemical in the Southern Hemisphere. The results show continued increases in the atmospheric abundance of HFC-23 and imply substantial increases in HFC-23 global emissions since 2003. These emission increases are coincident with rapidly increasing HCFC-22 production in developing countries and are observed despite efforts in recent years to limit emissions of HFC-23 through the Kyoto Protocol’s Clean Development Mechanism. These results will be considered along with new observations of additional HFCs from archived air, firn air, and ongoing flask-air measurements. Considered together, atmospheric increases observed for hydrochlorofluorocarbons and hydrofluorocarbons accounted for ~9% of the increase in total direct radiative forcing from anthropogenic gases during 2003-2008, an addition that was slightly larger than attributable to N2O over this same period.

Montzka, S. A.; Miller, B. R.; Battle, M. O.; Aydin, K. M.; Fahey, D. W.; Hall, B. D.; Miller, L.; Verhulst, K. R.; Saltzman, E.; McFarland, M.

2009-12-01

309

Selected Vuilleumier refrigerator performance characteristics  

NASA Technical Reports Server (NTRS)

Study of the performance characteristics of the Vuilleumier refrigerator for spacecraft applications. The effect on refrigerator performance of several important components and design parameters is examined. The components and design parameters selected for investigation include the cold-end heat conductance, cold regenerator, refrigerator rpm, and refrigerator sump temperature.

Sherman, A.

1973-01-01

310

Ejectors: applications in refrigeration technology  

Microsoft Academic Search

This paper provides a literature review on ejectors and their applications in refrigeration. A number of studies are grouped and discussed in several topics, i.e. background and theory of ejector and jet refrigeration cycle, performance characteristics, working fluid and improvement of jet refrigerator. Moreover, other applications of an ejector in other types of refrigeration system are also described.

Kanjanapon Chunnanond; Satha Aphornratana

2004-01-01

311

TRANSIENT ANALYSIS OF REFRIGERATION SYSTEM  

Microsoft Academic Search

The vapor compression refrigeration system consists of the basic components--compressor, condenser, expansion device and evaporator. For low temperature applications, an accumulator is also included between the evaporator and the compressor shell.^ The mathematical modelling of a refrigeration system involves developing of equations which predict the movement of refrigerant in the system and the change of state of refrigerant in the

MANMOHAN DHAR

1978-01-01

312

Final Technical Report HFC Concrete: A LowEnergy, Carbon- Dioxide- Negative Solution for Reducing Industrial Greenhouse Gas Emissions.  

National Technical Information Service (NTIS)

Solidia/CCSM received funding for further research and development of its Low Temperature Solidification Process (LTS), which is used to create hydrate-free concrete (HFC). LTS/HFC is a technology/materials platform that offers wide applicability in the b...

R. Riman

2012-01-01

313

Near azeotropic mixture substitute  

NASA Technical Reports Server (NTRS)

The present invention comprises a refrigerant mixture consisting of a first mole fraction of 1,1,1,2-tetrafluoroethane (R134a) and a second mole fraction of a component selected from the group consisting of a mixture of CHClFCF.sub.3 (R124) and CH.sub.3 CClF.sub.2 (R142b); a mixture of CHF.sub.2 CH.sub.3 (R152a) and CHClFCF.sub.3 (R124); a mixture of CHF.sub.2 CH.sub.3 (R152a) and CH.sub.3 CClF.sub.2 (R142b); and a mixture of CHClFCF.sub.3 (R124), CH.sub.3 CClF.sub.2 (R142b) and CHF.sub.2 CH.sub.3 (R152a).

Jones, Jack A. (Inventor)

1996-01-01

314

Solar refrigeration and cooling  

Microsoft Academic Search

In this paper a review of solar cooling and refrigeration technologies is presented. A discussion on the main reasons why these technologies are not presently economically feasible is carried out. and two installations in Mexico are analysed.

R. Best; N. Ortega

1999-01-01

315

Vuilleumier Cycle Cryogenic Refrigeration.  

National Technical Information Service (NTIS)

This report describes in detailed the Vuilleumier (V-M) refrigeration cycle and various ways it has been applied to produce cryogenic temperatures. It starts with the most theoretical model of the Vuilleumier cycle and gradually adds complicating factors ...

R. White

1976-01-01

316

Oxygen Chemisorption Cryogenic Refrigerator.  

National Technical Information Service (NTIS)

The present invention relates to a chemisorption compressor cryogenic refrigerator which employs oxygen to provide cooling at 60 K to 100 K. The invention includes dual vessels containing an oxygen absorbent material, alternately heated and cooled to prov...

J. A. Jones

1986-01-01

317

Refrigeration systems program summary.  

National Technical Information Service (NTIS)

In addition to saving energy, deploying advanced refrigeration technologies can substantially benefit the environment. Chlorofluorocarbons (CFCs) have been identified as a major cause of potential global climate change and about 20% of the CFCs consumed b...

1991-01-01

318

Joule Thomson refrigerator  

NASA Technical Reports Server (NTRS)

A bi-directional Joule Thomson refrigerator is described, which is of simple construction at the cold end of the refrigerator. Compressed gas flowing in either direction through the Joule Thomson expander valve and becoming liquid, is captured in a container in direct continuous contact with the heat load. The Joule Thomson valve is responsive to the temperature of the working fluid near the valve, to vary the flow resistance through the valve so as to maintain a generally constant flow mass between the time that the refrigerator is first turned on and the fluid is warm, and the time when the refrigerator is near its coldest temperature and the fluid is cold. The valve is operated by differences in thermal coefficients of expansion of materials to squeeze and release a small tube which acts as the expander valve.

Chan, Chung K. (inventor); Gatewood, John R. (inventor)

1988-01-01

319

Joule Thomson refrigerator  

NASA Astrophysics Data System (ADS)

A bi-directional Joule Thomson refrigerator is described, which is of simple construction at the cold end of the refrigerator. Compressed gas flowing in either direction through the Joule Thomson expander valve and becoming liquid, is captured in a container in direct continuous contact with the heat load. The Joule Thomson valve is responsive to the temperature of the working fluid near the valve, to vary the flow resistance through the valve so as to maintain a generally constant flow mass between the time that the refrigerator is first turned on and the fluid is warm, and the time when the refrigerator is near its coldest temperature and the fluid is cold. The valve is operated by differences in thermal coefficients of expansion of materials to squeeze and release a small tube which acts as the expander valve.

Chan, Chung K.; Gatewood, John R.

1988-10-01

320

Trifluoroacetate in the environment. Evidence for sources other than HFC\\/HCFCs  

Microsoft Academic Search

The partly halogenated Câ-hydro(chloro)fluorocarbons (HFC, HCFC) 1,1,1-trifluoro-2,2-dichloroethane (HCFC-123), 1,1,1,2-tetrafluoro-2-chloroethane (HCFC-124), and 1,1,1,2-tetrafluoroethane (HFC-134a) are CFC substitutes found at increasing levels in the atmosphere. Trifluoroacetate (TFA) is an atmospheric degradation product of these compounds and due to its persistence its potential accumulation in some aquatic ecosystems is a matter of environmental concern. The present study was undertaken to determine the present-days

Armin Jordan; Hartmut Frank

1999-01-01

321

Viscosity of gaseous HFC-143a (1,1,1-trifluoroethane) under high pressure  

SciTech Connect

The viscosity of gaseous HFC-143a(1,1,1-trifluoroethane) was measured with an oscillating-disk viscometer of the Maxwell type at temperatures from 298.15 to 423.15 K and at pressures up to the saturated vapor pressure at each temperature under subcritical conditions or up to 9 MPa under supercritical conditions. Intermolecular potential parameters of HFC-143a for the extended corresponding states were determined from the viscosity data at 0.1 MPa. An empirical viscosity equation as functions of temperature and density is proposed to interpolate the present experimental results.

Takahashi, M.; Shibasaki-Kitakawa, N.; Yokoyama, C. [Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science] [Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science

1999-03-01

322

Actinide extraction from simulated and irradiated spent nuclear fuel using TBP solutions in HFC-134a  

SciTech Connect

It was demonstrated that solutions of TBP-nitric acid adduct in liquid Freon HFC-134a (1.2 MPa, 25 deg. C) allowed for recovery of uranium with nearly the same effectiveness as supercritical CO{sub 2} at 30 MPa. At nearly quantitative recovery of U and Pu, a DF of ca. 10 can be attained on dissolution and extraction of simulated SNF samples. The possibility of recovery of actinides contained in cakes produced by oxide conversion of simulated and irradiated SNF with solutions of TBP and DBE in Freon HFC-134a was shown. (authors)

Shadrin, A.; Babain, V.; Kamachev, V.; Murzin, A.; Shafikov, D.; Dormidonova, A. [Khlopin Radium Institute, RPA, 28, 2-nd Murinskii ay., St-Petersburg (Russian Federation)

2008-07-01

323

Flow boiling heat transfer with HFC mixtures in a smooth horizontal tube. Part I: Experimental investigations  

Microsoft Academic Search

The substitution of working fluids in vapour-compression plants causes major problems, because of a reduced plant performance. Therefore, extremely accurate design procedures are needed, because the relative sizing of each plant-component is essential for the cycle performance. For this reason, the knowledge of the heat-transfer characteristics of new fluids in condensers and evaporators is mandatory. The heat-transfer characteristics of R410A

A. Greco; G. P. Vanoli

2005-01-01

324

DOE/AHAM advanced refrigerator technology development project  

SciTech Connect

As part of the effort to improve residential energy efficiency and reduce greenhouse emissions from power plants, several design options were investigated for improving the energy efficiency of a conventionally designed domestic refrigerator-freezer. The program goal was to reduce the energy consumption of a 20-ft{sup 3} (570-L) top-mount refrigerator-freeze to 1.00 kWh/d, a 50% reduction from the 1993 National Appliance Energy Conservation Act (NAECA) standard. The options--such as improved cabinet and door insulation, a high-efficiency compressor, a low-wattage fan, a large counterflow evaporator, and adaptive defrost control--were incorporated into prototype refrigerator-freezer cabinets and refrigeration systems. The refrigerant HFC-134a was used as a replacement for CFC-12. The baseline energy performance of the production refrigerator-freezers, along with cabinet heat load and compressor calorimeter test results, were extensively documented to provide a firm basis for experimentally measured energy savings. The project consisted of three main phases: (1) an evaluation of energy-efficient design options using computer simulation models and experimental testing, (2) design and testing of an initial prototype unit, and (3) energy and economic analyses of a final prototype. The final prototype achieved an energy consumption level of 0.93 kWh/d--an improvement of 45% over the baseline unit and 54% over the 1993 NAECA standard for 20-fg{sup 3} (570-L) units. The manufacturer`s cost for those improvements was estimated at $134; assuming that cost is doubled for the consumer, it would take about 11.4 years to pay for the design changes. Since the payback period was thought to be unfeasible, a second, more cost-effective design was also tested. Its energy consumption level was 1.16 kWh/d, a 42% energy savings, at a manufacturer`s cost increase of $53. Again assuming a 100% markup, the payback for this unit would be 6.6 years.

Vineyard, E.A.; Sand, J.R.; Rice, C.K.; Linkous, R.L.; Hardin, C.V.; Bohman, R.H.

1997-03-01

325

THERMODYNAMIC PERFORMANCE LIMIT AND EVAPORATOR DESIGN CONSIDERATIONS FOR NARM-BASED DOMESTIC REFRIGERATOR-FREEZER SYSTEMS  

EPA Science Inventory

The paper gives results of an investigation of non-azeotrophic refrigerant mixtures (NARMs) for a two-temperature-level heat exchange process found in a domestic refrigerator-freezer. deal (constant air temperature) heat exhcange processes are assumed. he results allow the effect...

326

Mixed refrigerants for a glass capillary micro cryogenic cooler  

NASA Astrophysics Data System (ADS)

Optimized mixed refrigerants are applied in Joule-Thomson (JT) micro cryogenic coolers (MCC) to enhance efficiency. Mixed refrigerants deliver equivalent refrigeration power with much lower pressure ratio and flow rate compared to pure nitrogen refrigerant. To determine the behavior of mixtures in MCCs, the normal boiling points of the components, mixture solubility, and refrigeration loss due to pressure drop on the low-pressure side of the heat exchanger are evaluated. The MCC discussed here was designed to operate at 77 K with the heat exchanger warm end precooled to 240 K by a thermo-electric cooler. An optimized five-component mixed refrigerant was calculated to provide a minimum isothermal enthalpy difference of 1.35 kJ/mol between 77 K and 240 K with a high pressure of 1.6 MPa and a low pressure of 0.1 MPa. Experimentally, a stable temperature of 140 K was achieved with a flow rate of 11 ?mol/s. A transient temperature of 76 K was observed.

Lin, M.-H.; Bradley, P. E.; Huber, Marcia L.; Lewis, R.; Radebaugh, R.; Lee, Y. C.

2010-08-01

327

Atmospheric lifetimes of HFC-143a and HFC-245fa: Flash photolysis resonance fluorescence measurements of the OH reaction rate constants  

SciTech Connect

Rate constants for the reactions of hydroxyl radicals with CH{sub 3}CF{sub 3} (HFC-143a) and CHF{sub 2}CH{sub 2}CF{sub 3} (HFC-245fa) have been measured using the flash photolysis resonance fluorescence technique over the temperature range 273-370 K. A data analysis procedure is presented which should minimize rate constant errors introduced by the possible effects of radical diffusion. Arrhenius expressions have been derived for the reactions of OH with CH{sub 3}CF{sub 3} and CHF{sub 2}CH{sub 2}CF{sub 3}, respectively. With these values, the atmospheric lifetimes for the two HFCs have been estimated to be 51 and 7.4 years, respectively. An error analysis is presented from which the rate constant uncertainty at any temperature can be calculated. 24 refs., 3 figs., 2 tabs.

Orkin, V.L.; Huie, R.E.; Kurylo, M.J. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1996-05-23

328

46 CFR 154.702 - Refrigerated carriage.  

Code of Federal Regulations, 2010 CFR

...Refrigerated carriage. (a) Each refrigeration system must: (1) Have...to the capacity of the largest refrigeration unit in the system. (b) For the purpose of this section, a “refrigeration unit” includes a...

2010-10-01

329

46 CFR 154.702 - Refrigerated carriage.  

Code of Federal Regulations, 2011 CFR

...Refrigerated carriage. (a) Each refrigeration system must: (1) Have...to the capacity of the largest refrigeration unit in the system. (b) For the purpose of this section, a “refrigeration unit” includes a...

2011-10-01

330

Die Teilsysteme von HfC mit TiC, ZrC, VC, NbC, TaC, Cr 3 C 2 , Mo 2 C (MoC), WC und UC  

Microsoft Academic Search

In Übereinstimmung mit der Volumregel sind die isotypen Monokarbide von Ti, Zr, Nb und Ta mit HfC lückenlos mischbar. HfC und Cr3C2 zeigen keinerlei gegenseitige Löslichkeit, dagegen löst HfC in sehr starkem Maße Mo2C bzw. MoC (über 80 Mol%). WC wird von HfC unter den gewählten Bedingungen bis gegen 40 Mol% aufgenommen. HfC und UC lösen sich weitgehend, entgegen der

H. Nowotny; R. Kieffer; F. Benesovsky; C. Brukl; E. Rudy

1959-01-01

331

Refrigeration principles and systems: An energy approach  

SciTech Connect

The book presents the fundamental principles, systems, and practices of refrigeration. Emphasizing energy conservation, it offers applications of the refrigeration systems and equipment. Topics covered include: physical principles; the vapor compression refrigeration system: Pressure-enthalpy diagrams; thermodynamics of the vapor compression refrigeration cycle; reciprocating, rotary and screw compressors; heat transfer in refrigeration: Evaporators; condensers and cooling towers; refrigerant flow control (expansion) devices; refrigerants, brines, oils, and contaminants; centrifugal compressors and systems; the refrigerant piping system; low temperature refrigeration; absorption refrigeration; the refrigeration load: Component balancing; electrical service systems; and Motor Controls and Protection.

Pita, E.G.

1984-01-01

332

HEAT TRANSFER EVALUATION OF HFC-236FA IN CONDENSATION AND EVAPORATION  

EPA Science Inventory

The report gives results of an evaluation of the shell-side heat transfer performance of hydrofluorocarbon (HFC)-236fa, which is considered to be a potential substitute for chlorofluorocarbon (CFC)-114 in Navy shipboard chillers, for both conventional finned [1024- and 1575-fpm (...

333

HEAT TRANSFER EVALUATION OF HFC-236FA IN CONDENSATION AND EVAPORATION  

EPA Science Inventory

The report gives results of an evaluation of the shell-side heat transfer performance of hydrofluorocarbon (HFC)-236fa, which is considered to be a potential substitute for chlorofluorocarbon (CFC)-114 in Navy shipboard chillers, for both conventional finned (1024- and 1575-fpm (...

334

Performance of ATM and variable length packet access in broadband HFC and wireless networks  

Microsoft Academic Search

We present an overview of some key features that enable superior performance and efficiency in medium access control (MAC) protocols for broadband wireless and hybrid fiber-coax (HFC) access networks. These features include: (1) minislots for transmission requests, (2) minislots for bandwidth allocation granularity, (3) centralized control for bandwidth allocation and fairness, (4) flexible transport capability for fixed-length (ATM) protocol data

K. Sriram

1998-01-01

335

Cable access beyond the hype: on residential broadband data services over HFC networks  

Microsoft Academic Search

Current efforts in digital data transmission over hybrid fiber coaxial (HFC) networks will provide an efficient data transport mechanism for the “last mile” to residential users and will enable a very large number of services to the home. Provision of these services requires a complete end-to-end network architecture that provides an efficient connection between the server and the end user.

C. Bisdikian; K. Maruyama; D. I. Seidman; D. N. Serpanos

1996-01-01

336

Performance Investigation into an IEEE 802.14 MAC Protocol for HFC Networks  

Microsoft Academic Search

The paper provides insight into the performance of a candidate IEEE 802.14 MAC protocol for hybrid fibre\\/coax (HFC) networks, by simulation. The simulations make use of two types of input traffic: measured traffic traces, and randomly generated memoryless traffic. It is confirmed that the protocol does not reach congestion collapse under any traffic load, and this is found to hold

Milosh V. Ivanovich; Moshe Zukerman; Ron Addie

1997-01-01

337

A MAC protocol for HFC networks: Design issues and performance evaluation  

Microsoft Academic Search

Medium Access Control (MAC) layer protocols are designed to control transmissions over shared mediums. Bi-directional Cable TV networks using Hybrid Fiber\\/Coazial (HFC) systems are good examples of broadcast environments where a MAC protocol is needed to allocate the multiaccess medium among the various nodes. One can think of a MAC protocol as a collection of components each performing a certain

Nada Golmie; Sandrine Masson; Gerard R. Pieris; David H. Su

1997-01-01

338

Two-way Broadband CATV-HFC Networks: State-of-the-Art and Future Trends  

Microsoft Academic Search

Cable modems allow two way digital data transmission between households and a central neighborhood server. In this overview we briefly describe some of the common characteristics of the Hybrid Fiber Coax (HFC) operation as presented by several standards bodies (both completed standards and works in progress). This includes a description and comparison of the media access control and physical layer

Stephen Perkins; Alan Gatherer

1999-01-01

339

Development and industrial use of HFC heating regime for rail heads of hypereutectoid steel  

Microsoft Academic Search

Railroad rails are usually delivered in the hot-rolled state or after bulk hardening (quenching in oil). While in service, only the heads of the rails are subject to wear (primarily the surface). In this connection, use of surface hardening, including the progressive and highly recommended method of hardening with HFC heating, is possible for the hardening of rails. The present

D. K. Nesterov; N. F. Levchenko; V. E. Sapozhkov; V. A. Dubrov

1991-01-01

340

HEAT TRANSFER EVALUATION OF HFC-236EA WITH HIGH PERFORMANCE ENHANCED TUBES IN CONDENSATION AND EVAPORATION  

EPA Science Inventory

The report gives results of an evaluation of the heat transfer performance of pure hydrofluorocarbon (HFC)-236ea for high performance enhanced tubes which had not been previously used in Navy shipboard chillers. Shell-side heat transfer coefficient data are presented for conde...

341

HEAT TRANSFER EVALUATION OF HFC-236EA WITH HIGH PERFORMANCE ENHANCED TUBES IN CONDENSATION AND EVAPORATION  

EPA Science Inventory

The report gives results of an evaluation of the heat transfer performance of pure hydrofluorocarbon (HFC)-236ea for high performance enhanced tubes which had not been previously used in Navy shipboard chillers. Shell-side heat transfer coefficient data are presented for condensa...

342

Downhole pulse tube refrigerators  

SciTech Connect

This report summarizes a preliminary design study to explore the plausibility of using pulse tube refrigeration to cool instruments in a hot down-hole environment. The original motivation was to maintain Dave Reagor`s high-temperature superconducting electronics at 75 K, but the study has evolved to include three target design criteria: cooling at 30 C in a 300 C environment, cooling at 75 K in a 50 C environment, cooling at both 75 K and 30 C in a 250 C environment. These specific temperatures were chosen arbitrarily, as representative of what is possible. The primary goals are low cost, reliability, and small package diameter. Pulse-tube refrigeration is a rapidly growing sub-field of cryogenic refrigeration. The pulse tube refrigerator has recently become the simplest, cheapest, most rugged and reliable low-power cryocooler. The authors expect this technology will be applicable downhole because of the ratio of hot to cold temperatures (in absolute units, such as Kelvin) of interest in deep drilling is comparable to the ratios routinely achieved with cryogenic pulse-tube refrigerators.

Swift, G.; Gardner, D. [Los Alamos National Lab., NM (United States). Condensed Matter and Thermal Physics Group

1997-12-01

343

Thermodynamic properties of HFC-338mccq, CF{sub 3}CF{sub 2}CF{sub 2}CH{sub 2}F, 1,1,1,2,2,3,3,4-octafluorobutane  

SciTech Connect

The authors report the thermodynamic properties of 1,1,1,2,2,3,3,4-octafluorobutane, which has been designated as HFC-338mccq by the refrigeration industry. The measurements span the temperature and pressure ranges encountered in thermal machinery. The properties measured include the vapor pressure, the density of the compressed liquid, the refractive index of both the saturated liquid and the saturated vapor, the critical temperature, the capillary rise, and the speed of sound in the vapor phase. These data were used to determine the ideal gas heat capacity, the saturated liquid and vapor densities, the surface tension, the virial equation of state for the vapor phase, and estimates of the critical pressure and density. A Carnahan-Starling-DeSantis equation of state was deduced from the measured fluid properties.

Defibaugh, D.R.; Carrillo-Nava, E.; Hurly, J.J.; Moldover, M.R.; Schmidt, J.W.; Weber, L.A. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1997-05-01

344

Toxicokinetics of 1,1,1,2-tetrafluoroethane (HFC134a) in male volunteers after experimental exposure  

Microsoft Academic Search

The aim of this study was to determine the uptake and disposition of inhaled 1,1,1,2-tetrafluoroethane (HFC-134a) in humans. Ten male volunteers were exposed to 500ppm HFC-134a (2h, 50W exercise). The HFC-134a levels were monitored in blood, exhaled air and urine up to 19h post-exposure.The concentration in blood increased rapidly, reaching a plateau of 9.4±1.9?M (mean±S.D.) within 30min, followed by a

Sara Gunnare; Lena Ernstgård; Bengt Sjögren; Gunnar Johanson

2006-01-01

345

Proceedings: Commercial Refrigeration Research Workshop  

SciTech Connect

Improving refrigeration systems for commercial use can enhance both utility load factors and supermarket profits. This workshop has pinpointed research needs in commercial refrigeration and systems integration for a supermarket environment.

None

1984-10-01

346

Cryogenic Refrigerators - An Updated Survey.  

National Technical Information Service (NTIS)

In 1969, we gave efficiency, weight, volume, and cost data for 95 cryogenic refrigerators and liquefiers excluding air separation plants. Recently, the survey was repeated. The original data and those for 49 additional refrigerators and liquefiers are pre...

T. R. Strobridge

1974-01-01

347

The Effect of Modified Atmosphere Packaging and Addition of Rosemary Extract, Sodium Acetate and Calcium Lactate Mixture on the Quality of Pre-cooked Hamburger Patties during Refrigerated Storage  

PubMed Central

The effect of modified atmosphere packaging (MAP; 30% CO2+70% N2 or 100% N2) and an additive mixture (500 ppm rosemary extract, 3,000 ppm sodium acetate and 1,500 ppm calcium lactate) on the quality of pre-cooked hamburger patties during storage at 5°C for 14 d was evaluated. The addition of the additive mixture reduced aerobic and anaerobic bacteria counts in both 30% CO2-MAP (30% CO2+70% N2) and 100% N2-MAP (p<0.05). The 30% CO2-MAP was more effective to suppress the microbial growth than 100% N2-MAP, moreover the 30% CO2-MAP combined with additive mixture resulted in the lowest bacterial counts. The hamburger patties with additive mixture showed lower CIE L* and CIE a*, and higher CIE b* than those with no additive mixture. The 30% CO2-MAP tended to decrease the TBARS during storage regardless of the addition of additives. The use of 30% CO2-MAP in combination with additives mixture was effective for maintaining the quality and extending the shelf-life of pre-cooked hamburger patties.

Muhlisin; Kang, Sun Moon; Choi, Won Hee; Lee, Keun Taik; Cheong, Sung Hee; Lee, Sung Ki

2013-01-01

348

Evaluation of design options for improving the energy efficiency of an environmentally safe domestic refrigerator-freezer  

SciTech Connect

In order to reduce greenhouse emissions from power plants and respond to regulatory actions arising from the National Appliance Energy Conservation Act (NAECA), several design options were investigated for improving the energy efficiency of a conventionally designed, domestic refrigerator-freezer. The options, such as improved cabinet insulation and high-efficiency compressor and fans, were incorporated into a prototype refrigerator-freezer cabinet and refrigeration system to produce a unit that is superior from an environmental viewpoint due to its lower energy consumption and the use of refrigerant HFC-134a as a replacement for CFC-12. Baseline energy performance of the original 1993 production refrigerator-freezer, along with cabinet heat load and compressor calorimeter test results, were extensively documented to provide a firm basis for experimentally measured energy savings. A detailed refrigerator system computer model was used to evaluate the energy savings for several design modifications that, collectively, could achieve a targeted energy consumption of 1.00 kWh/d for a 20 ft{sup 3} (570 l) top-mount, automatic-defrost, refrigerator-freezer. The energy consumption goal represents a 50% reduction in the 1993 NAECA standard for units of this size. Following the modeling simulation, laboratory prototypes were fabricated and tested to experimentally verify the analytical results and aid in improving the model in those areas where discrepancies occurred. While the 1.00 kWh/d goal was not achieved with the modifications, a substantial energy efficiency improvement of 22% (1.41 kWh/d) was demonstrated using near-term technologies. It is noted that each improvement exacts a penalty in terms of increased cost or system complexity/reliability. Further work on this project will analyze cost-effectiveness of the design changes and investigate alternative, more-elaborate, refrigeration system changes to further reduce energy consumption.

Vineyard, E.A.; Sand, J.R. [Oak Ridge National Lab., TN (United States); Bohman, R.H.

1995-03-01

349

ADVANCES IN SUPERMARKET REFRIGERATION SYSTEMS  

Microsoft Academic Search

Present supermarket refrigeration systems require very large refrigerant charges for their operation and can consume as much 1-1.5 million kWh annually. Several new approaches, such as distributed, secondary loop, low-charge multiplex, and advanced self-contained refrigeration systems, are available that utilize significantly less refrigerant. Analyses show that if properly designed and implemented, these advanced systems can reduce annual energy consumption by

Van D. Baxter

350

Solar powered refrigeration apparatus  

SciTech Connect

Solar powered refrigeration apparatus is disclosed in which an absorption refrigeration system is operated directly by solar energy. One end of a heat pipe is thermally connected to the boiler of the absorption refrigeration system, and a solar collector is thermally coupled to the other remote end of the heat pipe. The heat pipe is a sealed, evacuated metal tube partially filled with water. The solar collector is a double walled glass vacuum tube with a central axial opening for accommodating the remote end of the heat pipe. Heat energy collected by the solar collector boils the water in the heat pipe to subsequently condense in the area of the boiler thus transferring heat energy along the heat pipe to the boiler. The heat pipe is installed sloping downwardly away from the boiler to permit the return of condensate down the pipe to the solar collector area thus permitting continuous operation.

Theakston, F.H.

1982-12-07

351

Adsorption Refrigeration System  

SciTech Connect

Adsorption refrigeration is an environmentally friendly cooling technology which could be driven by recovered waste heat or low-grade heat such as solar energy. In comparison with absorption system, an adsorption system has no problems such as corrosion at high temperature and salt crystallization. In comparison with vapor compression refrigeration system, it has the advantages of simple control, no moving parts and less noise. This paper introduces the basic theory of adsorption cycle as well as the advanced adsorption cycles such as heat and mass recovery cycle, thermal wave cycle and convection thermal wave cycle. The types, characteristics, advantages and drawbacks of different adsorbents used in adsorption refrigeration systems are also summarized. This article will increase the awareness of this emerging cooling technology among the HVAC engineers and help them select appropriate adsorption systems in energy-efficient building design.

Wang, Kai [ORNL; Vineyard, Edward Allan [ORNL

2011-01-01

352

Optimization of solar absorption refrigerator  

Microsoft Academic Search

A solar refrigerator is made of a solar collector and a refrigeration system. Real solar refrigerators usually operate between two limits, maximum COP (coefficient of performance) and maximum cooling load. The relationships between the solar collector temperature, COP and cooling load are derived in this paper. The optimum collector temperatures under the conditions of either maximum COP or maximum cooling

Chih Wu; Lingen Chen; Fengrui Sun

1997-01-01

353

Status Of Sorption Cryogenic Refrigeration  

NASA Technical Reports Server (NTRS)

Report reviews sorption refrigeration. Developed for cooling infrared detectors, cryogenic research, and other advanced applications, sorption refrigerators have few moving parts, little vibration, and lifetimes of 10 years or more. Describes types of sorption stages, multistage and hybrid refrigeration systems, power requirements, cooling capacities, and advantages and disadvantages of various stages and systems.

Jones, Jack A.

1988-01-01

354

The vapor compression refrigeration cycle  

SciTech Connect

This article is a review of the basic principles of a cycle widely used to create the refrigeration effect that provides both human comfort and process cooling. While a semantic differentiation often is made for cooling and dehumidifying air for human comfort (air conditioning) and cooling for products and processes (refrigeration), all mechanical cooling applications depend on the previously mentioned refrigeration effect.

Pannkoke, T.

1995-11-01

355

Low-temperature magnetic refrigerator  

Microsoft Academic Search

The invention relates to magnetic refrigeration and more particularly to low temperature refrigeration between about 4 and about 20 K, with an apparatus and method utilizing a belt of magnetic material passed in and out of a magnetic field with heat exchangers within and outside the field operably disposed to accomplish refrigeration.

1983-01-01

356

Low-temperature magnetic refrigerator  

DOEpatents

The invention relates to magnetic refrigeration and more particularly to low temperature refrigeration between about 4 and about 20 K, with an apparatus and method utilizing a belt of magnetic material passed in and out of a magnetic field with heat exchangers within and outside the field operably disposed to accomplish refrigeration.

Barclay, J.A.

1983-05-26

357

Mixed-Gas Sorption Joule-Thomson Refrigerator  

NASA Technical Reports Server (NTRS)

Proposed mixed-gas sorption Joule-Thomson refrigerator provides cooling down to temperature of 70 K. Includes only one stage and no mechanical compressor. Simpler, operates without vibrating, and consumes less power in producing same amount of cooling. Same sorption principle of operation applicable in compressor that chemisorbs oxygen or hydrogen from mixture with helium, neon, and/or other nonreactive gases.

Jones, Jack A.; Petrick, S. Walter; Bard, Steven

1991-01-01

358

PERFORMANCE EVALUATION OF A VARIABLE SPEED, MIXED REFRIGERANT HEAT PUMP  

EPA Science Inventory

The report gives results of an evaluation of the performance of an innovative heat pump, equipped with a distillation column to shift the composition of a zeotropic refrigerant mixture. t gives results of U.S. Department of Energy (DOE) rating tests and seasonal energy calculatio...

359

Compressor calorimeter performance of refrigerant blends: Comparative methods and results for a refrigerator/freezer application  

SciTech Connect

A protocol was developed to define calorimeter operating pressures for nonazeotropic refrigerant mixtures (NARMs) which corresponded with the saturated evaporator and condenser temperatures commonly used for pure refrigerants. Compressor calorimeter results were obtained using this equivalent-mean-temperature (EMT) approach and a generally applied Association of Home Appliance Manufacturers (AHAM) procedure at conditions characteristic of a domestic refrigerator-freezer application. Tests with R-12 and two NARMs indicate that compressor volumetric and isentropic efficiencies are nearly the same for refrigerants with similar capacities and pressure ratios. The liquid-line temperature conditions specified in the AHAM calorimeter rating procedure for refrigerator-freezer compressors were found to preferentially derate NARM performance relative to R-12. Conversion of calorimeter data taken with a fixed liquid-line temperature to a uniform minimal level of condenser subcooling is recommended as a fairer procedure when NARMs are involved. Compressor energy-efficiency-ratio (EER) and capacity data measured as a result of the EMT approach were compared to system performance calculated using an equivalent-heat-exchanger-loading (EHXL) protocol based on a Lorenz-Meutzner (L-M) refrigerator-freezer modeling program. The EHXL protocol was used to transform the calorimeter results into a more relevant representation of potential L-M cycle performance. The EMT method used to set up the calorimeter tests and the AHAM liquid-line conditions combined to significantly understate the cycle potential of NARMs relative to that predicted at the more appropriate EHXL conditions. Compressor conditions representative of larger heat exchanger sizes were also found to give a smaller L-M cycle advantage relative to R-12.

Rice, C.K.; Sand, J.R.

1993-01-01

360

Performance of HC and HFC Refrigerants in a Finned-Tube Evaporator and Its Effect on System Efficiency.  

National Technical Information Service (NTIS)

The paper presents a comparable evaluation of isobutane (R600a), propane (R290), R134a, R22, R410A, and R32 in an optimized finned-tube evaporator, and analyzes the impact of evaporator effects on the system coefficient of performance (COP). The study rel...

D. Yashar M. Kim P. A. Domanski

2003-01-01

361

How to replace CFC refrigerants  

SciTech Connect

New guidelines show how to convert from CFCs (chlorofluorocarbons) to non-CFC refrigeration fluids. Federal regulations require that managers of operating facilities retrofit or replace refrigerants or entire cooling processes. Conversion from CFCs to bridge refrigerants (HCFC, hydrochlorofluorcarbons) or HFCs (hydrofluorocarbons) involves more than swapping out refrigerants. New refrigerants will affect cooling capacity and may adversely affect system operation. Preliminary investigations must focus on potential operational and equipment problems that can occur during a conversion. Inherent problem areas are: rotating equipment, mass flowrate, system heat-transfer capacity, system elastomers, gasketing, piping, lubrication oil compatibility, etc. The paper discusses the problems to consider in planning the phase-out strategy.

Wojdon, W.; George, M. (York International, Oakland, CA (United States))

1994-08-01

362

Dilution refrigeration for space applications  

NASA Technical Reports Server (NTRS)

Dilution refrigerators are presently used routinely in ground based applications where temperatures below 0.3 K are required. The operation of a conventional dilution refrigerator depends critically on the presence of gravity. To operate a dilution refrigerator in space many technical difficulties must be overcome. Some of the anticipated difficulties are identified in this paper and possible solutions are described. A single cycle refrigerator is described conceptually that uses forces other than gravity to function and the stringent constraints imposed on the design by requiring the refrigerator to function on the earth without using gravity are elaborated upon.

Israelsson, U. E.; Petrac, D.

1990-01-01

363

Refrigeration lubricating oil compositions  

SciTech Connect

Oil compositions are disclosed for effective use in the lubrication of rotary-type compressor for refrigeration equipment. The composition essentially comprises a polyglycol oil blended with specified amounts of at least one of additives or compounds of the group consisting of glycidyl ether type epoxy compounds, epoxidized fatty acid monoesters and epoxidized vegetable oils.

Morikawa, Y.; Sasaki, U.; Tsunemi, M.; Yamada, K.

1981-05-12

364

Energy Doubler Refrigeration System.  

National Technical Information Service (NTIS)

The Energy Doubler refrigeration system is required to cool long strings of warm iron magnets with a high degree of reliability and/or redundancy. The 6.5 km circumference together with the extremely small cooling channels dictated by the warm iron config...

C. Rode D. Richied S. Stoy P. C. VanderArend

1977-01-01

365

Solar Powered Refrigeration System  

NASA Astrophysics Data System (ADS)

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

Ewert, Michael K.; Bergeron, David J., III

2002-09-01

366

Oxygen chemisorption cryogenic refrigerator  

Microsoft Academic Search

The present invention relates to a chemisorption compressor cryogenic refrigerator which employs oxygen to provide cooling at 60 to 100 K. The invention includes dual vessels containing an oxygen absorbent material, alternately heated and cooled to provide a continuous flow of high pressure oxygen, multiple heat exchangers for precooling the oxygen, a Joule-Thomson expansion valve system for expanding the oxygen

Jack A. Jones

1987-01-01

367

Education in Helium Refrigeration  

SciTech Connect

On the one hand, at the end of the time I was active in helium refrigeration, I noticed that cryogenics was stepping into places where it was not yet used. For example, a conventional accelerator, operating at room temperature, was to be upgraded to reach higher particle energy. On the other hand, I was a little bit worried to let what I had so passionately learned during these years to be lost. Retirement made time available, and I came gradually to the idea to teach about what was my basic job. I thought also about other kinds of people who could be interested in such lessons: operators of refrigerators or liquefiers who, often by lack of time, did not get a proper introduction to their job when they started, young engineers who begin to work in cryogenics... and so on.Consequently, I have assembled a series of lessons about helium refrigeration. As the audiences have different levels of knowledge in the field of cryogenics, I looked for a way of teaching that is acceptable for all of them. The course is split into theory of heat exchangers, refrigeration cycles, technology and operation of main components, process control, and helium purity.

Gistau Baguer, G. M. [38330, Biviers (France)

2004-06-23

368

Fundamentals of Refrigeration.  

ERIC Educational Resources Information Center

This self-study course is designed to familiarize Marine enlisted personnel with the principles of the refrigeration process. The course contains five study units. Each study unit begins with a general objective, which is a statement of what the student should learn from the unit. The study units are divided into numbered work units, each…

Sutliff, Ronald D.; And Others

369

Solar Powered Refrigeration System  

NASA Technical Reports Server (NTRS)

A solar powered vapor compression refrigeration system is made practicable with thermal storage and novel control techniques. In one embodiment, the refrigeration system includes a photovoltaic panel, a variable speed compressor, an insulated enclosure, and a thermal reservoir. The photovoltaic (PV) panel converts sunlight into DC (direct current) electrical power. The DC electrical power drives a compressor that circulates refrigerant through a vapor compression refrigeration loop to extract heat from the insulated enclosure. The thermal reservoir is situated inside the insulated enclosure and includes a phase change material. As heat is extracted from the insulated enclosure, the phase change material is frozen, and thereafter is able to act as a heat sink to maintain the temperature of the insulated enclosure in the absence of sunlight. The conversion of solar power into stored thermal energy is optimized by a compressor control method that effectively maximizes the compressor's usage of available energy. A capacitor is provided to smooth the power voltage and to provide additional current during compressor start-up. A controller monitors the rate of change of the smoothed power voltage to determine if the compressor is operating below or above the available power maximum, and adjusts the compressor speed accordingly. In this manner, the compressor operation is adjusted to convert substantially all available solar power into stored thermal energy.

Ewert, Michael K. (Inventor); Bergeron, David J., III (Inventor)

2002-01-01

370

Improved cryogenic refrigeration system  

NASA Technical Reports Server (NTRS)

Two-position shuttle valve simplifies valving arrangement and crank-shaft configuration in gas-balancing and Stirling-cycle refrigeration systems used to produce temperatures below 173 degrees K. It connects the displacer and regenerator alternately to the supply line or the return line of the compressor, and establishes constant pressure on the drive piston.

Higa, W. H.

1967-01-01

371

Cycling Joule Thomson refrigerator  

Microsoft Academic Search

A symmetrical adsorption pump\\/compressor system having a pair of mirror image legs and a Joule Thomson expander, or valve, interposed between the legs thereof for providing a, efficient refrigeration cycle is described. The system further includes a plurality of gas operational heat switches adapted selectively to transfer heat from a thermal load and to transfer or discharge heat through a

E. Tward

1983-01-01

372

A thermoanalytical study on the oxidation of ZrC and HfC powders with formation of carbon  

Microsoft Academic Search

The oxidation of ZrC and HfC powders was thermoanalytically investigated by simultaneous thermogravimetry (TG), differential thermal analysis (DTA) and mass spectrometry (MS) at various oxygen pressures (PO2) between 0.5 and 40 kPa in the temperature range 20–1000 °C. TG results showed that the oxidation of ZrC and HfC begins at a fixed temperature of 380 and 400 °C, respectively, independent

Shiro Shimada

2002-01-01

373

Study to determine the existence of an azeotropic R-22 `drop-in` substitute  

SciTech Connect

The reduction in chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) production and the scheduled phase-out of these ozone depleting refrigerants requires the development and determination of environmentally safe refrigerants for use in heat pumps, water chillers, air conditioners, and refrigerators. Azeotropic mixtures are attractive as alternative refrigerants because they behave very nearly as pure materials. A simple correlative scheme that allows one to judge whether or not an azeotrope is likely in a binary refrigerant mixture is discussed. This paper presents laboratory and computer simulation model evaluation of two of the azeotropic refrigerant mixtures which are identified, HFC-134a (1,1,1,2-tetrafluoroethane) with R-C290 (Propane) and HFC-134a with R-600a (Isobutane), in a generic heat pump apparatus. A third azeotropes mixture, HFC-134a with R-C290 (Cyclopropane) is examined by computer simulation only.

Kim, M.S.; Morrison, G.; Mulroy, W.J.; Didion, D.A.

1996-03-01

374

10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.  

Code of Federal Regulations, 2010 CFR

...Definitions concerning commercial refrigerators, freezers and refrigerator-freezers. 431.62 Section 431.62 Energy DEPARTMENT...INDUSTRIAL EQUIPMENT Commercial Refrigerators, Freezers and Refrigerator-Freezers § 431.62...

2010-01-01

375

10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.  

Code of Federal Regulations, 2010 CFR

...Definitions concerning commercial refrigerators, freezers and refrigerator-freezers. 431.62 Section 431.62 Energy DEPARTMENT...INDUSTRIAL EQUIPMENT Commercial Refrigerators, Freezers and Refrigerator-Freezers § 431.62...

2009-01-01

376

10 CFR 431.62 - Definitions concerning commercial refrigerators, freezers and refrigerator-freezers.  

Code of Federal Regulations, 2011 CFR

...refrigerator, freezer, and refrigerator-freezer means refrigeration equipment that— (1) Is not a consumer product (as defined...Holding temperature application means a use of commercial refrigeration equipment other than a pull-down temperature...

2011-01-01

377

16 CFR Appendix A2 to Part 305 - Refrigerators and Refrigerators-Freezers With Manual Defrost  

Code of Federal Regulations, 2010 CFR

...false Refrigerators and Refrigerators-Freezers With Manual Defrost A2 Appendix A2 to Part 305 Commercial Practices FEDERAL...305âRefrigerators and Refrigerators-Freezers With Manual Defrost Range Information Manufacturer's Rated Total...

2009-01-01

378

16 CFR Appendix A2 to Part 305 - Refrigerators and Refrigerators-Freezers With Manual Defrost  

Code of Federal Regulations, 2010 CFR

...false Refrigerators and Refrigerators-Freezers With Manual Defrost A2 Appendix A2 to Part 305 Commercial Practices FEDERAL...305âRefrigerators and Refrigerators-Freezers With Manual Defrost Range Information Manufacturer's Rated Total...

2010-01-01

379

Magnetic refrigeration apparatus with belt of ferro or paramagnetic material  

DOEpatents

A magnetic refrigerator operating in the 12 to 77 K range utilizes a belt which carries ferromagnetic or paramagnetic material and which is disposed in a loop which passes through the center of a solenoidal magnet to achieve cooling. The magnetic material carried by the belt, which can be blocks in frames of a linked belt, can be a mixture of substances with different Curie temperatures arranged such that the Curie temperatures progressively increase from one edge of the belt to the other. This magnetic refrigerator can be used to cool and liquefy hydrogen or other fluids.

Barclay, J.A.; Stewart, W.F.; Henke, M.D.; Kalash, K.E.

1986-04-03

380

Thermodynamic optimization of solar-driven refrigerators  

Microsoft Academic Search

This paper describes the thermodynamic optimization of a class of refrigerators without work input, which are driven by heat transfer from a solar collector. The model consists of a finite-size solar collector with heat loss to the ambient, and a refrigerator with three finite-size heat exchangers, namely, the evaporator between refrigeration load and refrigerant, the condenser between the refrigerant and

J. V. C. Vargas; A. Bejan; M. Sokolov

1996-01-01

381

Evaluation of alternative refrigerant—adsorbent pairs for refrigeration cycles  

Microsoft Academic Search

The refrigerant-adsorbent pairs at present preferred for solid-sorption refrigeration cycles are ammonia-carbon, methanol-carbon, ammonia salts and water-zeolite. Porosity tests have been carried out on a range of alternatives, including R32 and butane, as refrigerants and new monolithic carbon adsorbents. The results of fitting to the Dubinin equation and modelling of cycles based on these pairs are presented. Ammonia is still

R. E. Critoph

1996-01-01

382

Synchronized DMT for multipoint-to-point communications on HFC networks  

Microsoft Academic Search

This paper presents a method for synchronizing a large number of discrete-multitone-based modems for multipoint-to-point communications on hybrid fiber-coax (HFC) networks. Each newly-installed remote unit is first loop-timed to the central modem master clock. Ranging is then performed to determine the sample delay required to align at the central unit receiver the symbols transmitted by the remote with those transmitted

Krista S. Jacobsen; J. A. C. Bingham; J. M. Cioffi

1995-01-01

383

MLAP: a MAC level access protocol for the HFC 802.14 network  

Microsoft Academic Search

Interactive residential broadband\\/multimedia services are expected to be the next main event in the cyberspace experience. The large excess bandwidth (well over 300 MHz) available in today's cable TV (CATV) hybrid fiber\\/coaxial (HFC) plants is an ideal candidate to provide the underlying communications infrastructure for interactive digital services to the home; cable operators that have not yet upgraded their all-coaxial

C. Bisdikian; B. McNeil; R. Norman; R. Zeisz

1996-01-01

384

The dielectric constant of liquid HFC 134a and HCFC 142b  

Microsoft Academic Search

This paper presents measurements of the dielectric constant of HFC 134a and HCFC 1426, as a function of pressure and temperature, in the temperature range from 200 to 300 K and pressures up to 20 M Pa, using a direct capacitance method, The samples used had a stated purity of 99.8 and 99.9%, respectively, The values of the dielectric constant

M. T. Barão; U. V. Mardolear; C. A. Nieto de Castro

1996-01-01

385

ms START: A random access algorithm for the IEEE 802.14 HFC network  

Microsoft Academic Search

In this paper we introduce the n-ary Multi-slot Stack Random Access Algorithm (msSTART) for use in an IEEE 802.14 hybrid fiber\\/coaxial (HFC) network. The msSTART random access algorithm (RAA) is an evolution of the stack-based START algorithm. It is an easy to implement, high-efficiency, free-access, robust, stable RAA optimized to operate in an environment where contention slots could dynamically change.

Chatschik Bisdikian; Bill Mcneil; Rob Norman

1996-01-01

386

A simulation-based study of TCP dynamics over HFC networks  

Microsoft Academic Search

New broadband access technologies such as hybrid fiber coaxial (HFC) are likely to provide fast and cost effective support to a variety of applications including video on demand (VoD), inter-active computer games, and Internet-type applications such as Web browsing, ftp, e-mail, and telephony. Since most of these applications use TCP as the transport layer protocol, the key to their efficiency

Omar Elloumi; Nada Golmie; Hossam Afifi; David H. Su

2000-01-01

387

Dynamical quality of service (QoS) support for DOCSIS HFC networks  

Microsoft Academic Search

The Data Over Cable Service Interface Specifications (DOCSIS) of the Multimedia Cable Network System (MCNS) organization intends to support IP traffics over HFC (hybrid fiber\\/coax) networks with significantly higher data rates than analog modems and Integrated Service Digital Network (ISDN) links. The availability of high speed-access enables the delivery of high quality audio, video and interactive services. To support quality-of-service

Wen-Kuang Kuo; Sunil Kumar; C.-C. Jay Kuo

2001-01-01

388

The thermal conductivity of liquid 1,1,1,2-tetrafluoroethane (HFC 134a)  

Microsoft Academic Search

The thermal conductivity of HFC 134a was measured in the liquid phase with the polarized transient hot-wire technique. The\\u000a experiments were performed at temperatures from 213 to 293 K at pressures up to 20 MPa. The data were analyzed to obtain correlations\\u000a in terms of density and pressure. This study is part of an international project coordinated by the Subcommittee

A. N. Gurova; U. V. Mardolcar; C. A. Nieto de Castro

1997-01-01

389

Review of solid adsorption solar refrigerator I: an overview of the refrigeration cycle  

Microsoft Academic Search

A review of the practically realized solid adsorption solar refrigeration cycles is presented. The cycles also have potentials for use as heat pumps. They have been classified according to the adsorbate utilized as: cycles with water as refrigerant, cycles using fluorocarbon as refrigerant, cycles using ammonia as refrigerant and cycles with alcohols as refrigerant. The performances of these refrigeration cycles,

E. E Anyanwu

2003-01-01

390

Compact acoustic refrigerator  

DOEpatents

A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

Bennett, Gloria A. (Los Alamos, NM)

1992-01-01

391

Superfluid thermodynamic cycle refrigerator  

DOEpatents

A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of [sup 3]He in a single phase [sup 3]He-[sup 4]He solution. The [sup 3]He in superfluid [sup 4]He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid [sup 3]He at an initial concentration in superfluid [sup 4]He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of [sup 4]He while restricting passage of [sup 3]He. The [sup 3]He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K. 12 figs.

Swift, G.W.; Kotsubo, V.Y.

1992-12-22

392

Solar energy refrigeration device  

SciTech Connect

The invention relates to a refrigeration device using solar energy. This device includes a refrigeration fluid, such as water, which circulates between the solar energy heat exchanger containing zeolite, and an evaporator located in a cooling chamber through a condenser, then return to the exchanger through a three way valve. The device includes a second channel in the exchanger, which channel includes a fluid, and a second exchanger consisting of a tube with fins connected to a storage tank containing water at various temperatures. During the day whenever the period of sunshine is not sufficient, additional heat in the form of hot water is provided to the exchanger. Conversely if the night temperature is not low enough, cooling in the exchanger is assisted by a cooling device located in the second channel. Hot water 25/sup 0/ C. is provided by the excess heat produced by the sun at day's end.

Wiart, A.; Paeye, G.

1985-04-09

393

Solar powered refrigeration unit  

SciTech Connect

A solar powered refrigeration unit includes an array of solar cells connected in series-parallel configuration to produce more than 12 volts dc. One side of the array is grounded, and the positive output is connected through a diode to the positive terminal of a storage battery. The diode is configured to prevent the battery discharging through the solar cell array. The array is also connected to one side of a back to back diode arrangement, the junction of which is connected through a thermocouple to a voltage controlled relay. The refrigeration unit compressor is connected to the relay, which is switched on by the thermocouple. The back to back diode arrangement permits the greater voltage of the solar cell array or the storage battery to power the compressor.

Miller, A.J.; Kortzeborn, R.

1984-10-02

394

Oxygen chemisorption cryogenic refrigerator  

NASA Astrophysics Data System (ADS)

The present invention relates to a chemisorption compressor cryogenic refrigerator which employs oxygen to provide cooling at 60 to 100 K. The invention includes dual vessels containing an oxygen absorbent material, alternately heated and cooled to provide a continuous flow of high pressure oxygen, multiple heat exchangers for precooling the oxygen, a Joule-Thomson expansion valve system for expanding the oxygen to partially liquefy it and a liquid oxygen pressure vessel. The primary novelty is that, while it was believed that once oxygen combined with an element or compound the reaction could not reverse to release gaseous oxygen, in this case oxygen will indeed react in a reversible fashion with certain materials and will do so at temperatures and pressures which make it practical for incorporation into a cryogenic refrigeration system.

Jones, Jack A.

1987-10-01

395

Superfluid thermodynamic cycle refrigerator  

DOEpatents

A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

Swift, Gregory W. (Santa Fe, NM); Kotsubo, Vincent Y. (La Canada, CA)

1992-01-01

396

Transient Mixing Characteristics of Refrigerant with Refrigeration Oil  

NASA Astrophysics Data System (ADS)

Mixing of refrigerant with refrigeration oil has great influence on viscosity and foaming of the oil in refrigerant compressors. This paper dealt with transient characteristics of mixing process of refrigerant into refrigeration oil. The mixing phenomena were investigated by using an experimental apparatus which modeled process of the oil-refrigerant mixing in a casing of refrigerant compressors. Mass of refrigerant dissolved into the oil stored in a cylindrical vessel was recorded continuously under different conditions of pressure, temperature, amount of the oil, diameter of the vessel and combination of the refrigerant and the oil. On the other hand, the mixing phenomena were analyzed theoretically by two mathematical models, one is a one-dimensional diffusion model and the other is a mass transfer model. Based on the comparison of theoretical and experimental results, values of apparent diffusion coefficient and mean mass transfer coefficient were decided. The mixing process can be easily predicted by these models, but an applicable range of mass transfer model is wider than that of diffusion model. The mixing characteristics were correlated by a non-dimensional equation composed of Schmidt number, Grashof number and aspect ratio in the diffusion model and by another non-dimensional equation composed of Sherwood number, Schmidt number and Grashof number in the mass transfer model.

Fukuta, Mitsuhiro; Yanagisawa, Tadashi; Shimizu, Takashi; Tanno, Hideki; Ogi, Yasuhiro

397

Thermal conductivity of halogenated ethanes, HFC-134a, HCFC-123, and HCFC-141b  

SciTech Connect

The gaseous thermal conductivity of three CFC alternatives, HFC-134a (1,1,1,2-tetrafluoroethane), HCFC-123 (1,1-dichloro-2,2,2-trifluoroethane), and HCFC-141b (1,1-dichloro-1-fluoroethane), has been measured in the temperature ranges 273-363 K (HFC-134a) and 313-373K (HCFC-123, JCFC-141b) at pressures up to saturation. The measurements were performed with a new improved transient hot-wire apparatus. The uncertainty of the experimental data is estimated to be within 1%. The gaseous thermal conductivity obtained in this work together with the liquid thermal-conductivity data from the literature were correlated with temperature and density by an empirical equation based on the excess thermal-conductivity concept. The equation is found to represent the experimental results with average deviations of 2.5% for HFC-134a, 0.75% for HCFC-123, and 0.55% for HCFC-141B, respectively.

Yamamoto, R. (Kyoto Univ. (Japan)); Matsuo, S.; Tanaka, Y. (Kobe Univ. (Japan))

1993-01-01

398

Measurements of the PVT Properties of HCFC123 and HFC134a  

NASA Astrophysics Data System (ADS)

The vapor pressure and PVT properties in a superheated vapor and compressed liquid phase region of two environmentally acceptable hydrogen-containing halocarbons (HCFC123 and HFC134a) were determined experimentally. The measurements of vapor pressure and PVT properties were made using constant-volume method. Sixty-five vapor pressure points were obtained in the range of temperature of 314 K to critical temperature for HCFC123, and forty-one vapor pressure points were obtained in the range of temperature of 262K to critical temperature for HFC134a. Fifty-nine PVT data points were obtained in the range of temperature 352K to 484K, of pressure 0.5 to 5.2MPa and of density 29 to 1030 kg/m3. And sixty-three PVT data points, were obtained in the range of temperature 294K to 424K, of pressure 0.6 to 5.7MPa and of density 24 to 1101kg/m3. On the basis of these results, the critical pressure was determined to be 3.672MPa for HCFC123, and it was determined to be 4.055MPa for HFC134a. In addition, the equation of state and vapor pressure correlation were developed.

Fukushima, Masato; Watanabe, Naohiro; Kamimura, Toru

399

The thermal conductivity of liquid 1,1,1,2-tetrafluoroethane (HFC-134a)  

SciTech Connect

The thermal conductivity of HFC 134a was measured in the liquid phase with the polarized transient hot-wire technique. The experiments were performed at temperatures from 213 to 293 K at pressures up to 20 MPa. The data were analyzed to obtain correlations in terms of density and pressure. This study is part of an international project coordinated by the Subcommittee on Transport Properties of Commission I.2 of IUPAC, conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of HFC 134a, using samples of different origin. Two samples of HFC 134a from different sources have been used. The thermal conductivity of the first sample was measured along the saturation line as a function of temperature and the data were presented earlier. The thermal conductivity of the second one, the round-robin sample, was measured as a function of pressure and temperature. These data were extrapolated to the saturation line and compared with the data obtained, previously in order to demonstrate the importance of the sample origin and their real purity. The accuracy of the measurements is estimated to be 0.5%. Finally, the results are compared with the existing literature data.

Gurova, A.N.; Mardolcar, U.V. [Inst. Superior Tecnico, Lisboa (Portugal). Dept. de Fisica; Nieto de Castro, C.A. [Univ. de Lisboa (Portugal)

1997-09-01

400

Saturated Liquid Densities of HCFC123, HFC134a, CFC11 and CFC12  

NASA Astrophysics Data System (ADS)

The saturated liquid densities of two environmentally acceptable hydrogen-containing halocarbons (HCFC123 and HFC134a) and two fully halogenated chlorofluorocarbons (CFCl1 and CFC12) were determined experimentally. The measurement has been conducted by the method using pyrex glass floats. Eleven saturated liquid densities were obtained in the range of temperature from 281 to 352 K for HCFC123. Seven saturated liquid densities were obtained in the range of temperature from 244 to 292 K for HFC134a. Eleven saturated liquid densities were obtained in the range of temperature from 285 to 361 K for CFC11. And ten saturated liquid densities were obtained in the range of temperature from 237 to 297 K for CFC12. The uncertainties of temperature and density are less than ±20 mK and ±3 kg/m3, respectively. On the basis of these results, the saturated liquid density correlations were developed for four halocarbons. The satuated liquid densities for HCFC123 are close to those for CFC11. And the saturated liquid densities for HFC134a are smaller than those for CFC12.

Fukushima, Masato

401

Reciprocating Magnetic Refrigerator  

NASA Technical Reports Server (NTRS)

Unit cools to 4 K by adiabatic demagnetization. Two porous matrices of paramagnetic material gadolinium/gallium/garnet held in long piston called displacer, machined out of Micarta (phenol formaldehyde polymer). Holes in side of displacer allow heat-exchange fluid to flow to and through matrices within. Piston seals on displacer prevent substantial mixing of fluid in two loops. Magnetic refrigerator provides continuous rather than "one-shot" cooling.

Johnson, D. L.

1985-01-01

402

Refrigeration and Food Safety  

MedlinePLUS

... Administrative Forms Standard Forms Skip Navigation Z7_0Q0619C0JGR010IFST1G5B10H1 Web Content Viewer (JSR 286) Actions ${title} Loading... / Topics / ... Food Safety / Refrigeration and Food Safety Z7_0Q0619C0JGR010IFST1G5B10H3 Web Content Viewer (JSR 286) Actions ${title} Loading... Z7_ ...

403

Multilayer Thermionic Refrigeration  

SciTech Connect

A new method of refrigeration is proposed. Efficient cooling is obtained by thermionic emission of electrons over Schottky barriers between metals and semiconductors. Since the barriers have to be thin, each barrier can have only a small temperature difference ({approximately}1 K) . Macroscopic cooling is obtained with a multilayer device. The same device is also an efficient generator of electrical power. A complete analytic theory is provided. {copyright} {ital 1998} {ital The American Physical Society}

Mahan, G.D.; Woods, L.M. [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)] [Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States); [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6030 (United States)

1998-05-01

404

Multilayer Thermionic Refrigeration  

SciTech Connect

A review is presented of our program to construct an efficient solid state refrigerator based on thermionic emission of electrons over periodic barriers in the solid. The experimental program is to construct a simple device with one barrier layer using a three layers: metal-semiconductor-metal. The theoretical program is doing calculations to determine: (i) the optimal layer thickness, and (ii) the thermal conductivity.

Mahan, G.D.

1999-08-30

405

Japanese activities in refrigeration technology  

NASA Astrophysics Data System (ADS)

This paper reviews recent activities in refrigeration technology in Japan. The projects described are stimulated by growing industrial needs or form part of large national projects. The JNR project on the MAGLEV train is currently the most powerful activity and it demands knowledge in all the different disciplines of cryogenics in particular on various scales of refrigeration. Research activities are also directed towards the development of Stirling cycle and magnetic refrigerators for applications in a wider area.

Fujita, T.; Ohtsuka, T.; Ishizaki, Y.

406

NICE3: Industrial Refrigeration System  

SciTech Connect

Energy Concepts has developed an absorption-augmented system as a cost-effective means of achieving more cooling capacity with a substantial reduction in energy consumption and greenhouse gas emissions for industrial refrigeration. It cuts fuel consumption by 30% by combining an internal combustion engine with a mechanical compression refrigeration system and an absorption refrigeration system. The absorption system is powered by engine waste heat. Conventional industrial refrigeration uses mechanical vapor compression, powered by electric motors, which results in higher energy costs. By the year 2010, the new system could cut fuel consumption by 19 trillion Btu and greenhouse emissions by more than 1 million tons per year.

Simon, P.

1999-09-29

407

Simulation of the Energy Saver Refrigeration System.  

National Technical Information Service (NTIS)

The helium refrigeration for the Energy Saver is supplied by a Central Helium Liquefier and 24 Satellite Refrigerators installed over a 1-1/4 square mile area. An interactive, software simulator has been developed to calculate the refrigeration available ...

H. R. Barton J. E. Nicholls G. T. Mulholland

1981-01-01

408

Sorption Compressor/Mechanical Expander Hybrid Refrigeration.  

National Technical Information Service (NTIS)

Experience with Deep Space Network (DSN) ground-based cryogenic refrigerators has proved the reliability of the basic two-stage Gifford-McMahon helium refrigerator. A very long life cryogenic refrigeration system appears possible by combining this expansi...

J. A. Jones M. Britcliffe

1987-01-01

409

21 CFR 1250.34 - Refrigeration equipment.  

Code of Federal Regulations, 2013 CFR

Each refrigerator shall be equipped with a thermometer located in the warmest portion thereof. Waste water drains from ice boxes, refrigerating equipment, and refrigerated spaces shall be so installed as to prevent backflow of contaminating...

2013-04-01

410

Investigations on two-phase heat exchanger for mixed refrigerant Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

The design of the recuperative heat exchanger used to pre-cool the refrigerant mixture prior to J-T expansion is crucial for the efficient operation of the mixed refrigerant Joule- Thomson (MR J-T) cryocooler. The multi-component non-azeotropic refrigerant mixture undergoes boiling and condensation heat transfer simultaneously in the heat exchanger. Therefore, it is important to analyze the performance of the heat exchanger in terms of temperature distribution with respect to the mixture of gases used. In the present work, temperature measurements are carried out at the ends of the heat exchanger for high pressure stream, while eight sensors are installed at equal distance along the length of heat exchanger to measure temperature of low pressure stream. The paper reports variation in heat transfer coefficient along the length of the heat exchanger. The variation is discussed with respect to temperature distribution across the length and changes in thermo-physical properties of the gas mixture.

Ardhapurkar, Purushottam; Sridharan, Arunkumar; Atrey, Milind

2012-06-01

411

Air Conditioning and Refrigeration Equipment (Peru). Refrigeration Equipment, April 1992.  

National Technical Information Service (NTIS)

Demand for refrigeration equipment in Peru is lower than expected due to many factors including the effects of 'El Nino', the warming trend of the Humboldt current in the Pacific Ocean. However, demand for coolers and refrigerators for perishable meats, f...

1992-01-01

412

Condensation of refrigerants flowing inside smooth and corrugated tubes  

SciTech Connect

Because heat exchanger thermal performance has a direct fluence on the overall cycle performance of vapor-compression refrigeration machinery,enhanced heat transfer surfaces are of interest to improve the efficiency of heat pumps and air conditioners. We investigated R-22 and a nonazeotropic refrigerant mixture (NARM) of 75% R-143a and 25% R-124 (by mass) to study their thermal performance in a condenser made of conventional smooth tubes and another condenser made of corrugated, or spirally indented, tubes. We investigated the condensing heat transfer and pressure drop characteristics in an experimental test loop model of a domestic beat pump system employing a variable speed compressor. The refrigerant circulates inside the central tube and the water circulates in the annulus. At refrigerant mass fluxes of approximately 275--300 kg/m{sup 2}s, the measured irreversible pressure drop of the corrugated surface was 23% higher than that of the smooth surface for the R-22. At refrigerant mass fluxes of 350-370 kg/m{sup 2}s, the irreversible pressure drop of the corrugated surface was 36% higher than that of the smooth surface for the NARM. The average heat transfer coefficient for the corrugated surface for R-22 was roughly 40% higher than that for the smooth tube surface at refrigerant mass fluxes of 275--295 kg/m{sup 2}s. The average heat transfer coefficient for the corrugated surface for the NARM was typically 70% higher than that for the smooth tube surface at refrigerant mass fluxes of 340--385 kg/m{sup 2}s.

Hinton, D.L. [Tennessee State Univ., Nashville, TN (United States); Conklin, J.C.; Vineyard, E.A. [Oak Ridge National Lab., TN (United States)

1995-07-01

413

Toxicokinetics of 1,1,1,2-tetrafluoroethane (HFC-134a) in male volunteers after experimental exposure.  

PubMed

The aim of this study was to determine the uptake and disposition of inhaled 1,1,1,2-tetrafluoroethane (HFC-134a) in humans. Ten male volunteers were exposed to 500 ppm HFC-134a (2 h, 50 W exercise). The HFC-134a levels were monitored in blood, exhaled air and urine up to 19 h post-exposure. The concentration in blood increased rapidly, reaching a plateau of 9.4+/-1.9 microM (mean+/-S.D.) within 30 min, followed by a fast post-exposure decrease. HFC-134a in expired air decreased rapidly as well and in parallel with that in blood. The post-exposure urinary excretion was 0.002% of the inhaled amount, and the half-time was 58 min (pooled data). A physiologically based toxicokinetic (PBTK) model was developed for further analysis. Experimental and simulated time courses in blood and exhaled air agreed well in all 10 subjects. Further, the late decay in blood was consistent with a wash-out of HFC-134a from fat tissues, with a half-time of 114+/-21 min. The simulated relative uptake during exposure was 3.7+/-0.5%. No remarkable findings were observed in the electrocardiographic recordings. Fibrinogen in plasma increased 1 day after exposure, whereas no effects on C-reactive protein, serum amyloid A protein, D-dimer or uric acid were seen. Further studies are needed to investigate the possible inflammatory response. PMID:17030466

Gunnare, Sara; Ernstgård, Lena; Sjögren, Bengt; Johanson, Gunnar

2006-11-01

414

Regenerative Sorption Refrigerator  

NASA Technical Reports Server (NTRS)

Two-stage sorption refrigerator achieves increased efficiency via regenerative-heating concept in which waste heat from praseodymium/cerium oxide (PCO) chemisorption compressor runs charcoal/krypton (C/Kr) sorption compressor. Waste heat from each PCO sorption compressor used to power surrounding C/Kr sorption compressor. Flows of heat in two compressor modules controlled by gas-gap thermal switches. Has no wearing moving parts other than extremely long life, room-temperature check valves operating about twice per hour. Virtually no measurable vibration, and has potential operating life of at least ten years.

Jones, Jack A.; Wen, Liang-Chi; Bard, Steven

1991-01-01

415

Sun synchronous solar refrigeration  

NASA Astrophysics Data System (ADS)

The primary goal of this project was to prototype a complete Sun Synchronous Solar Powered Refrigerator. The key element to the technology is the development of the hermetic motor compressor assembly. The prototype was to be developed to either the stage where Polar Products could receive additional venture capital or to the point whereby Polar could use their own capital to manufacture the systems. Our goal was to construct a prototype which would be the next step to a proven and market ready product. To demonstrate the technology under laboratory conditions was a very minimal goal.

416

A novel absorption refrigeration cycle  

Microsoft Academic Search

For the purpose of improving the performance of conventional single effect absorption refrigeration cycle, this paper proposed a novel absorption refrigeration cycle with an expander–compressor. Simulation results show that the COP of the proposed cycle is much higher than that of conventional single effect cycle and two stage cycle at the most simulated conditions when the integrated efficiency is higher

Daliang Hong; Limin Tang; Yijian He; Guangming Chen

2010-01-01

417

Low-Temperature Magnetic Refrigerator.  

National Technical Information Service (NTIS)

The invention relates to magnetic refrigeration and more particularly to low temperature refrigeration between about 4 and about 20 K, with an apparatus and method utilizing a belt of magnetic material passed in and out of a magnetic field with heat excha...

J. A. Barclay

1983-01-01

418

Semiconductor-based optical refrigerator  

DOEpatents

Optical refrigerators using semiconductor material as a cooling medium, with layers of material in close proximity to the cooling medium that carries away heat from the cooling material and preventing radiation trapping. In addition to the use of semiconducting material, the invention can be used with ytterbium-doped glass optical refrigerators.

Epstein, Richard I. (Santa Fe, NM); Edwards, Bradley C. (Nekoosa, WI); Sheik-Bahae, Mansoor (Albuquerque, NM)

2002-01-01

419

Computer Simulation and Optimization of Ammonia-Water Absorption Refrigeration Systems  

Microsoft Academic Search

The ammonia-water absorption refrigeration system is attracting increasing research interests, since the system can be powered by waste thermal energy, thus avoiding using ozone-depletion refrigerants and reducing demand on electricity supply. In the article, a mathematical model coupled with detailed equations for thermodynamic properties of an ammonia-water mixture is described A computer simulation software based on the model is developed.

DA-WEN SUN

1997-01-01

420

JPL research to develop a He-3/He-4 dilution refrigerator for space applications  

NASA Technical Reports Server (NTRS)

A research program to develop a He-3/He-4 solution refrigerator for space applications is underway. The results of the effort to use an electric field as a substitute for gravity to control the He-3/He-4 mixture interface that separates phases in terrestrial units are described. Further, experimental results obtained from an engineering model of a single-cycle dilution refrigerator with a mixing chamber capable of operating in a zero-gravity environment are described. Future research and development plans are outlined, in particular the need to test the operation of a single-cycle as well as a continuously operating dilution refrigerator in space.

Petrac, D.; Israelsson, U. E.; Jackson, H. W.; Strayer, D. M.

1990-01-01

421

Computer simulation and optimization of ammonia-water absorption refrigeration systems  

SciTech Connect

The ammonia-water absorption refrigeration system is attracting increasing research interests, since the system can be powered by waste thermal energy, thus avoiding using ozone-depletion refrigerants and reducing demand on electricity supply. In the article, a mathematical model coupled with detailed equations for thermodynamic properties of an ammonia-water mixture is described. A computer simulation software based on the model is developed. With the software, the performance characteristics of ammonia-water absorption refrigeration systems are analyzed, and detailed optimum operation maps for the systems are presented. These maps can be used as guides in choosing operating conditions for designing such systems or for existing systems.

Sun, D.W. [National Univ. of Ireland, Dublin (Ireland)

1997-08-01

422

Helium dilution refrigeration system  

DOEpatents

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

Roach, P.R.; Gray, K.E.

1988-09-13

423

Helium dilution refrigeration system  

DOEpatents

A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

Roach, Patrick R. (Darien, IL) [Darien, IL; Gray, Kenneth E. (Naperville, IL) [Naperville, IL

1988-01-01

424

Heat transfer of oil-contaminated HFC134a in a horizontal evaporator  

Microsoft Academic Search

The introduction of chlorine-free refrigerants to the market requires experimental investigations of their behaviour in heat pumps and refrigerators. One particular area of interest is the effect of the new oils on the heat transfer in evaporators and condensers. Oil can either increase or decrease the heat transfer coefficient. This paper presents the results from an experimental investigation of the

K Hambraeus

1995-01-01

425

Near azeotropic mixture substitute for dichlorodifluoromethane  

NASA Technical Reports Server (NTRS)

A refrigerant and a process of formulating thereof that consists of a mixture of a first mole fraction of CH.sub.2 FCF.sub.3 and a second mole fraction of a component selected from the group consisting of a mixture of CHClFCF.sub.3 and CH.sub.3 CClF.sub.2 ; a mixture of CHF.sub.2 CH.sub.3 and CH.sub.3 CClF.sub.2 ; and a mixture of CHClFCF.sub.3, CH.sub.3 CClF.sub.2 and CHF.sub.2 CH.sub.3.

Jones, Jack A. (Inventor)

1998-01-01

426

Atmospheric degradation mechanisms of hydrogen containing chlorofluorocarbons (HCFC) and fluorocarbons (HFC)  

NASA Technical Reports Server (NTRS)

The current knowledge of atmospheric degradation of hydrogen containing chlorofluorocarbons (HCFC 22 (CHClF2), HCFC 123 (CHCl2CF3), HCFC 124 (CHClFCF3), HCFC 141b (CFCl2CH3), HCFC 142b (CF2ClCH3)) and fluorocarbons (HFC 125 (CHF2CF3), HFC 134a (CH2FCF3), HFC 152a (CHF2CH3)) is assessed. Except for the initiation reaction by OH radicals, there are virtually no experimental data available concerning the subsequent oxidative breakdown of these molecules. However, from an analogy to the degradation mechanisms of simple alkanes, some useful guidelines as to the expected intermediates and final products can be derived. A noteable exception from this analogy, however, appears for the oxi-radicals. Here, halogen substitution induces new reaction types (C-Cl and C-C bond ruptures) which are unknown to the unsubstituted analogues and which modify the nature of the expected carbonyl products. Based on an evaluation of these processes using estimated bond strength data, the following simplified rules with regards to the chlorine content of the HCFC's may be deduced: (1) HCFC's containing one chlorine atom such as 22 and 142b seem to release their chlorine content essentially instantaneous with the initial attack on the parent by OH radicals, and for HCFC 124, such release is apparently prevented; (2) HCFC's such as 123 and 141b with two chlorine atoms are expected to release only one of these instantaneously; and the second chlorine atom may be stored in potentially long-lived carbonyl compounds such as CF3CClO or CClFO.

Zellner, Reinhard

1990-01-01

427

Trifluoroacetate in the environment. Evidence for sources other than HFC/HCFCs  

SciTech Connect

The partly halogenated C{sub 2}-hydro(chloro)fluorocarbons (HFC, HCFC) 1,1,1-trifluoro-2,2-dichloroethane (HCFC-123), 1,1,1,2-tetrafluoro-2-chloroethane (HCFC-124), and 1,1,1,2-tetrafluoroethane (HFC-134a) are CFC substitutes found at increasing levels in the atmosphere. Trifluoroacetate (TFA) is an atmospheric degradation product of these compounds and due to its persistence its potential accumulation in some aquatic ecosystems is a matter of environmental concern. The present study was undertaken to determine the present-days base level of environmental TFA and whether model calculations are in line with the actual data. Average levels of about 120 ng L{sup {minus}1} as predicted for the year 2010 are found in rain in Germany already now, slightly higher than in rain collected in Switzerland or Nevada. In the major rivers in Germany, TFA is present at average concentrations of 140 ng L{sup {minus}1}. In air, levels of 45--60 pg m{sup {minus}3} have been found in Central Europe. Between March 1995 and September 1996, a period of substantial increase in atmospheric HFC-134a mixing ratio, the TFA concentrations in air and precipitation did not significantly increase. TFA is absent in old groundwater samples, and in river water from remote locations, concentrations are low. These data suggest that the total TFA in both compartments exceeds the formation potential of currently known sources, that TFA in atmosphere and rain is regionally associated with industrial or population density, and that other unresolved sources must contribute to the present concentrations.

Jordan, A.; Frank, H. [Univ. of Bayreuth (Germany)] [Univ. of Bayreuth (Germany)

1999-02-15

428

Commercial Refrigeration Resource Assessment : Final Report  

Microsoft Academic Search

The purpose of this report is to assess the Pacific Northwest's commercial refrigeration market and to identify current conservation technologies that can improve the efficiency of refrigeration systems in supermarkets, restaurants, and refrigerated warehouses and thus provide the region with substantial energy savings in the form of demand reduction. This report describes potentially cost-effective conservation technologies for electric refrigeration systems

G. A. Wikler; Taghi Alereza

1988-01-01

429

Modeling supermarket refrigeration energy use and demand  

Microsoft Academic Search

A computer model has been developed that can predict the performance of supermarket refrigeration equipment to within 3% of field test measurements. The Supermarket Refrigeration Energy Use and Demand Model has been used to simulate currently available refrigerants R-12, R-502 and R-22, and is being further developed to address alternative refrigerants. This paper reports that the model is expected to

M. H. Blatt; M. K. Khattar; D. H. Walker

1991-01-01

430

Viscosity of gaseous HFC-134a (1,1,1,2-tetrafluoroethane) under high pressures  

SciTech Connect

The viscosity of gaseous HFC-134a (1,1,1,2-tetrafluoroethane) was measured with an oscillating disk viscometer of the Maxwell type from 298.15 to 398.15 K at pressures up to 5.5 MPa. Intermolecular potential parameters for the Lennard-Jones 12-6 model were determined from the viscosity data at 0.1 MPa. The viscosity equation developed by Krauss et al. was applied to correlate the present viscosity data. In addition, the correlations proposed by Stiel and Thodos and by Lee and Thodos were tested for fitting the experimental viscosity data.

Shibasaki-Kitakawa, N.; Takahashi, M.; Yokoyama, C. [Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science] [Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction Science

1998-09-01

431

Magnetic refrigeration for maser amplifier cooling  

NASA Technical Reports Server (NTRS)

The development of a multifrequency upconverter-maser system for the DSN has created the need to develop a closed-cycle refrigerator (CCR) capable of providing more than 3 watts of refrigeration capability at 4.5 K. In addition, operating concerns such as the high cost of electrical power consumption and the loss of maser operation due to CCR failures require that improvements be made to increase the efficiency and reliability of the CCR. One refrigeration method considered is the replacement of the Joule-Thomson expansion circuit with a magnetic refrigeration. Magnetic refrigerators can provide potentially reliable and highly efficient refrigeration at a variety of temperature ranges and cooling power. The concept of magnetic refrigeration is summarized and a literature review of existing magnetic refrigerator designs which have been built and tested and that may also be considered as possibilities as a 4 K to 15 K magnetic refrigeration stage for the DSN closed-cycle refrigerator is provided.

Johnson, D. L.

1982-01-01

432

Vuilleumier Refrigerator Analysis. Low Temperature Refrigerator Design Optimization.  

National Technical Information Service (NTIS)

In published analyses of the Vuilleumier refrigeration cycle, it has been assumed that the gas in the various volumes of the system go through variations in pressure isothermally. Actually, the gas approaches isentropic conditions in these volumes, leadin...

R. A. Ackermann

1971-01-01

433

Cryogenic refrigeration apparatus  

DOEpatents

A technique for producing a cold environment in a refrigerant system in which input fluid from a compressor at a first temperature is introduced into an input channel of the system and is pre-cooled to a second temperature for supply to one of at least two stages of the system, and to a third temperature for supply to another stage thereof. The temperatures at such stages are reduced to fourth and fifth temperatures below the second and third temperatures, respectively. Fluid at the fourth temperature from the one stage is returned through the input channel to the compressor and fluid at the fifth temperature from the other stage is returned to the compressor through an output channel so that pre-cooling of the input fluid to the one stage occurs by regenerative cooling and counterflow cooling and pre-cooling of the input fluid to the other stage occurs primarily by counterflow cooling. 6 figs.

Crunkleton, J.A.

1992-03-31

434

Quantum absorption refrigerator.  

PubMed

A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold, and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified; the cooling power J(c) vanishes as J(c) ? T(c)(?), when T(c)?0, where ?=d+1 for dissipation by emission and absorption of quanta described by a linear coupling to a thermal bosonic field, where d is the dimension of the bath. PMID:22401189

Levy, Amikam; Kosloff, Ronnie

2012-02-17

435

Multistation refrigeration system  

NASA Technical Reports Server (NTRS)

A closed cycle refrigeration (CCR) system is disclosed for providing cooling at different parts of a maser. The CCR includes a first station for cooling the maser's parts, except the amplifier portion, to 4.5 K. The CCR further includes means with a 3.0 K station for cooling the maser's amplifier to 3.0 K and, thereby, increases the maser's gain and/or bandwith by a significant factor. The means which provide the 3.0 K cooling include a pressure regulator, heat exchangers, an expansion valve, and a vacuum pump, which coact to cause helium, provided from a compressor, to liquefy and thereafter expand so as to vaporize. The heat of vaporization for the helium is provided by the maser amplifier, which is thereby cooled to 3.0 K.

Wiebe, E. R. (inventor)

1978-01-01

436

Cryogenic refrigeration apparatus  

DOEpatents

A technique for producing a cold environment in a refrigerant system in which input fluid from a compressor at a first temperature is introduced into an input channel of the system and is pre-cooled to a second temperature for supply to one of at least two stages of the system, and to a third temperature for supply to another stage thereof. The temperatures at such stages are reduced to fourth and fifth temperatures below the second and third temperatures, respectively. Fluid at the fourth temperature from the one stage is returned through the input channel to the compressor and fluid at the fifth temperature from the other stage is returned to the compressor through an output channel so that pre-cooling of the input fluid to the one stage occurs by regenerative cooling and counterflow cooling and pre-cooling of the input fluid to the other stage occurs primarily by counterflow cooling.

Crunkleton, James A. (Cambridge, MA) [Cambridge, MA

1992-01-01

437

Using Acid Number as a Leading Indicator of Refrigeration and Air Conditioning System Performance  

SciTech Connect

This report summarizes a literature review to assess the acidity characteristics of the older mineral oil and newer polyolester (POE) refrigeration systems as well as to evaluate acid measuring techniques used in other non-aqueous systems which may be applicable for refrigeration systems. Failure in the older chlorofluorocarbon/hydrochlorofluorocarbon (CFC/HCFC) / mineral oil systems was primarily due to thermal degradation of the refrigerant which resulted in the formation of hydrochloric and hydrofluoric acids. These are strong mineral acids, which can, over time, severely corrode the system metals and lead to the formation of copper plating on iron surfaces. The oil lubricants used in the older systems were relatively stable and were not prone to hydrolytic degradation due to the low solubility of water in oil. The refrigerants in the newer hydrofluorocarbon (HFC)/POE systems are much more thermally stable than the older CFC/HCFC refrigerants and mineral acid formation is negligible. However, acidity is produced in the new systems by hydrolytic decomposition of the POE lubricants with water to produce the parent organic acids and alcohols used to prepare the POE. The individual acids can therefore vary but they are generally C5 to C9 carboxylic acids. Organic acids are much weaker and far less corrosive to metals than the mineral acids from the older systems but they can, over long time periods, react with metals to form carboxylic metal salts. The salts tend to accumulate in narrow areas such as capillary tubes, particularly if residual hydrocarbon processing chemicals are present in the system, which can lead to plugging. The rate of acid production from POEs varies on a number of factors including chemical structure, moisture levels, temperature, acid concentration and metals. The hydrolysis rate of reaction can be reduced by using driers to reduce the free water concentration and by using scavenging chemicals which react with the system acids. Total acid number (TAN), which includes both mineral acids and organic acids, is therefore a useful indicator which can be used to monitor the condition of the system in order to perform remedial maintenance, when required, to prevent system failure. The critical TAN value is the acid level at which remedial action should be taken to prevent the onset of rapid acid formation which can result in system failure. The level of 0.05 mg KOH/g of oil was established for CFC/mineral oil systems based on analysis of 700 used lubricants from operating systems and failed units. There is no consensus within the refrigeration industry as to the critical TAN value for HFC/POE systems, however, the value will be higher than the CFC/mineral oil systems critical TAN value because of the much weaker organic acids produced from POE. A similar study of used POE lubricants should be performed to establish a critical TAN limit for POE systems. Titrimetric analysis per ASTM procedures is the most commonly used method to determine TAN values in lubricants in the refrigeration industry and other industries dealing with lubricating oils. For field measurements, acid test kits are often used since they provide rapid, semi-quantitative TAN results.

Dennis Cartlidge; Hans Schellhase

2003-07-31

438

Integrated services to the home and small business over a service-independent HFC network  

NASA Astrophysics Data System (ADS)

This paper proposes three different approaches to providing integrated digital services to small businesses and residential customers over modern hybrid fiber and coaxial (HFC) access networks. The target delivery system is one that is flexible and forms a multiservice, service- independent platform capable of providing a wide range of services (voice, video, data, and multimedia). The merits and limitations of the three approaches are explored. In the first approach, the common facilities of an HFC access network may be shared by the frequency partitioning of the coaxial plant's radio frequency spectrum. video, data, and telephony services each use different portions of this spectrum -- a service-dependent network. In the second approach, asynchronous transfer mode (ATM) transmission is used as the information delivery vehicle all the way to the home or small business, creating a more flexible delivery system. The ATM-based architecture is expected to support any service or service mix -- a service-independent network. In the third approach, a common transport protocol composed of both asynchronous and synchronous transfer modes (ATM/STM) is used. Such an approach could (1) provide a common interface between home/small business premises equipment and both the circuit and ATM switching networks; (2) meet a wide range of delay and throughput requirements; and (3) allow for many network migration scenarios.

Counterman, Raymond

1995-11-01

439

Superinsulation in refrigerators and freezers.  

National Technical Information Service (NTIS)

The results presented here were obtained during Phase 4 of the first CRADA, which had the specific objective of determining the lifetime of superinsulations when installed in simulated refrigerator doors. The second CRADA was established to evaluate and t...

E. Vineyard T. K. Stovall K. E. Wilkes K. W. Childs

1998-01-01

440

Control system for thermoelectric refrigerator  

NASA Technical Reports Server (NTRS)

Apparatus including a power supply (202) and control system is provided for maintaining the temperature within an enclosed structure (40) using thermoelectric devices (92). The apparatus may be particularly beneficial for use with a refrigerator (20) having superinsulation materials (46) and phase change materials (112) which cooperate with the thermoelectric device (92) to substantially enhance the overall operating efficiency of the refrigerator (20). The electrical power supply (202) and control system allows increasing the maximum power capability of the thermoelectric device (92) in response to increased heat loads within the refrigerator (20). The electrical power supply (202) and control system may also be used to monitor the performance of the cooling system (70) associated with the refrigerator (20).

Nelson, John L. (Inventor); Criscuolo, Lance (Inventor); Gilley, Michael D. (Inventor); Park, Brian V. (Inventor)

1996-01-01

441

ISS Update: Solar Powered Refrigerator  

NASA Video Gallery

NASA Public Affairs Officer Dan Huot interviews Mike Ewert, Life Support and Thermal Systems Engineer. Ewert co-invented the solar powered refrigerator for stowage of medical samples, preservation ...

442

Magnetic Refrigeration Apparatus and Method.  

National Technical Information Service (NTIS)

The disclosure relates to refrigeration through magnetizing and demagnitizing a body by rotating it within a magnetic field. Internal and external heat exchange fluids and in one embodiment, a regenerator, are used. (ERA citation 09:014441)

J. A. Barclay W. C. Overton W. F. Stewart

1983-01-01

443

NICE3: Industrial Refrigeration System.  

National Technical Information Service (NTIS)

Energy Concepts has developed an absorption-augmented system as a cost- effective means of achieving more cooling capacity with a substantial reduction in energy consumption and greenhouse gas emissions for industrial refrigeration. It cuts fuel consumpti...

P. Simon

1999-01-01

444

Closed cycle liquid helium refrigerators.  

National Technical Information Service (NTIS)

We have developed closed cycle liquid helium refrigerators using a Joule Thomson circuit precooled by commercially available two staged Gifford Mac Mahon cryocoolers. The Joule Thomson counterflow heat exchangers are modular and have been thermo-hydraulic...

G. Claudet R. Lagnier A. Ravex

1992-01-01

445

Refrigeration plants for the SSCL  

SciTech Connect

The basic requirements and operating features of the collider cryogenic system have already been described in other publications. The general arrangement of the refrigeration plant and its subsystems is presented, and the issue of how to provide redundancy in the cryogenic system is addressed, and some of the basic features of the refrigeration plants are described. The collider cryogenic system design is not final yet, and this report only reflects the direction and current status of the cryogenic system design.

McAshan, M.; Ganni, V.; Than, R.; Niehaus, T.

1991-03-01

446

Thermoelectric refrigerator for gas analyzer  

Microsoft Academic Search

The authors describe a thermoelectric refrigerator for an air analyzer which cools an airstream by 24-30.4 K for a flow rate of 0.3 m³\\/h and a power consumption of less than or equal to 33.2 W. The setup time is 45 minutes. This refrigerator makes it possible to increase the average temperature of the heat-absorbing junction of the thermopile and

G. V. Bochin; V. I. Butyrskii; L. N. Karaseva

1987-01-01

447

Short-Cycle Adsorption Refrigerator  

NASA Technical Reports Server (NTRS)

Modular adsorption/Joule-Thomson-effect refrigerator offers fast regeneration; adsorption/desorption cycle time expected to be 1 minute. Pressurized hydrogen generated by bank of compressor modules during heating phase passes through system of check valves and expands in Joule-Thomson junction as it enters refrigeration chamber. Hydrogen absorbs heat from load before it is sucked out by another bank of compressor modules in cooling phase.

Chan, C. K.

1988-01-01

448

Ten degree Kelvin hydride refrigerator  

NASA Technical Reports Server (NTRS)

A compact hydride absorption refrigeration system with few moving parts for 10 Kelvin operation is disclosed and comprises liquid hydrogen producing means in combination with means for solidifying and subliming the liquid hydrogen produced. The liquid hydrogen is sublimed at about 10 Kelvin. By using a symmetrical all hydrogen redundant loop system, a 10 Kelvin refrigeration system can be operated for many years with only a fraction of the power required for prior art systems.

Jones, Jack A. (inventor)

1987-01-01

449

Initial parametric results using CYCLEZ: A LMTD-specified, Lorenz-Meutzner cycle refrigerator-freezer model  

NASA Astrophysics Data System (ADS)

A computer model representing a two-evaporator, two-intercooler refrigerator-freezer operating at steady-state with nonazeotropic refrigerant mixtures (CYCLEZ) has been developed at Oak Ridge National Laboratory (ORNL). This model is being used to assess the effects of system design and operating parameters on the cycle performance of a refrigerator-freezer designed around the Lorenz-Meutzner (L-M) circuit. Separate evaporators for the freezer and fresh-food compartments are modeled, as well as two intercoolers that subcool liquid refrigerant from the condenser by heat transfer with low-pressure refrigerant. The CYCLEZ refrigerator/freezer model is derived from the CYCLEZ heat-pump model developed originally by the National Institute of Standards and Technology (NIST). CYCLEZ currently uses the Carnahan-Starling-DeSantis (CSD) equation-of-state to compute refrigerant thermodynamic properties, so that new refrigerants can easily be added. Condenser and evaporator heat-exchanger performance are defined by user-specified overall LMTDs which allow equivalent heat-exchanger sizing per unit refrigeration load to be maintained for different refrigerant mixtures. A more consistent formulation of overall heat-exchanger LMTD is applied across the condenser superheated and two-phase regions as well as over the two evaporators. Source and sink conditions are specified in terms of inlet and outlet temperatures of the external fluid streams. Intercooler high-side (subcooling) delta Ts and relative fresh-food-to-freezer load ratio are also user-specified. These features make this model well suited for evaluating the optimal thermodynamic cycle requirements of the five heat exchangers used in the L-M refrigerator/freezer circuit.

Rice, C. Keith; Sand, James R.

450

Initial parametric results using CYCLEZ---An LMTD-specified, Lorenz-Meutzner cycle refrigerator-freezer model  

SciTech Connect

A computer model representing a two-evaporator, two-intercooler refrigerator-freezer operating at steady-state with nonazeotropic refrigerant mixtures (CYCLEZ) has been developed at Oak Ridge National Laboratory (ORNL). This model is being used to assess the effects of system design and operating parameters on the cycle performance of a refrigerator-freezer designed around the Lorenz- Meutzner (L-M) circuit. Separate evaporators for the freezer and fresh-food compartments are modeled, as well as two intercoolers that subcool liquid refrigerant from the condenser by heat transfer with low-pressure refrigerant. The CYCLEZ refrigerator/freezer model is derived form the CYCLEZ heat-pump model developed originally by the National Institute of Standards and Technology (NIST). CYCLEZ currently uses the Carnahan-Starling-DeSantis (CSD) equation-of-state to compute refrigerant thermodynamic properties , so that new refrigerants can easily be added. Condenser and evaporator heat-exchanger performance are defined by user-specified overall LMTDs which allow equivalent heat-exchanger sizing per unit refrigeration load to be maintained for different refrigerant mixtures. A more consistent formulation of overall heat-exchanger LMTD is applied across the condenser superheated and two-phase regions as well as over the two evaporators. Source and sink conditions are specified in terms of inlet and outlet temperatures of the external fluid streams. Intercooler high-side (subcooling) {delta} Ts and relative fresh-food-to-freezer load ratio are also user-specified. These features make this model well suited for evaluating the optimal thermodynamic cycle requirements of the five heat exchangers used in the L-M refrigerator/freezer circuit. 13 refs., 6 figs., 1 tab.

Rice, C.K.; Sand, J.R.

1990-01-01

451

An Evaluation of the Thermal Conductivity of Extruded Polystyrene Foam Blown with HFC134a or HCFC142b  

Microsoft Academic Search

Insulation performance of extruded polystyrene (XPS) foams expanded with various halogenated blowing agents including HFC-134a or HCFC-142b was measured over time. Residual blowing agents were measured after aging up to 26 years. The diffusive transport properties of the blowing agents can be determined through the mathematical calculation of the heat transfer in the gas phase component of the foam thermal

Chau V. Vo; Andrew N. Paquet

2004-01-01

452

Saturated liquid densities and bubble-point pressures of the binary HFC 152a+HCFC 142b system  

NASA Astrophysics Data System (ADS)

Forty-eight sets of the saturated liquid densities and bubble-point pressures of the binary HFC 152a + HCFC 142b system were measured with a magnetic densimeter coupled with a variable-volume cell. The measurements obtained at four compositions, 20, 40, 60, and 80 wt%, of HFC 152a cover a range of temperatures from 280 to 400 K. The experimental uncertainties in temperature, pressure, density, and composition were estimated to be within ±15mK, ±20kPa, ±0.2%, and between -0.14 and ±0.01 wt% HFC 152a (-0.01 and + 0.14 wt% HCFC 142b), respectively. The purities of the samples were 99.9 wt% for HFC 152a and 99.8 wt% for HCFC 142b. A binary interaction parameter, k ij , in the Peng-Robinson equation of state was determined as a function of temperature for representing the bubble-point pressures. On the other hand, two constant binary-interaction parameters, k ij and l ij , were introduced into the mixing rule of the Hankinson-Brobst-Thomson equation for representing the saturated liquid densities.

Maezawa, Y.; Widiatmo, J. V.; Sato, H.; Watanabe, K.

1991-11-01

453

Mixture Experiments  

SciTech Connect

A mixture experiment involves combining two or more components in various proportions or amounts and then measuring one or more responses for the resulting end products. Other factors that affect the response(s), such as process variables and/or the total amount of the mixture, may also be studied in the experiment. A mixture experiment design specifies the combinations of mixture components and other experimental factors (if any) to be studied and the response variable(s) to be measured. Mixture experiment data analyses are then used to achieve the desired goals, which may include (i) understanding the effects of components and other factors on the response(s), (ii) identifying components and other factors with significant and nonsignificant effects on the response(s), (iii) developing models for predicting the response(s) as functions of the mixture components and any other factors, and (iv) developing end-products with desired values and uncertainties of the response(s). Given a mixture experiment problem, a practitioner must consider the possible approaches for designing the experiment and analyzing the data, and then select the approach best suited to the problem. Eight possible approaches include 1) component proportions, 2) mathematically independent variables, 3) slack variable, 4) mixture amount, 5) component amounts, 6) mixture process variable, 7) mixture of mixtures, and 8) multi-factor mixture. The article provides an overview of the mixture experiment designs, models, and data analyses for these approaches.

Piepel, Gregory F.

2007-12-01

454

Auto defrost refrigerator  

SciTech Connect

A refrigerator is described including: an upper freezer compartment, a lower fresh food compartment and an insulating partition separating the compartments; an evaporator chamber separate from the freezer and fresh food compartment and above the fresh food compartment; means for conducting relatively cold air from the chamber to the freezer compartment and means for conducting relatively cold air from the chamber to the fresh food compartment; return means for returning relatively warm air from the freezer compartment to the chamber; duct means connecting the lower portion of the fresh food compartment with the chamber for returning relative warm air from the fresh food compartment to the chamber; evaporator means, including a first evaporator section positioned in the evaporator chamber and a second evaporator section positioned in the duct means, for cooling air passing thereover; and fan means for withdrawing relatively warm air from the compartments, circulating the air from the freezer compartment over the first evaporator section, circulating the air from the fresh food compartment serially over both the second and first evaporator sections and discharging cooled air from the evaporator chamber.

Schulze, J.L.

1988-05-03

455

46 CFR 151.40-11 - Refrigeration systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Refrigeration systems. 151.40-11 Section...Control Installations § 151.40-11 Refrigeration systems. (a) Boiloff systems... (b) Vapor compression, tank refrigeration, and secondary refrigeration...

2011-10-01

456

46 CFR 151.40-11 - Refrigeration systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Refrigeration systems. 151.40-11 Section...Control Installations § 151.40-11 Refrigeration systems. (a) Boiloff systems... (b) Vapor compression, tank refrigeration, and secondary refrigeration...

2010-10-01

457

46 CFR 151.40-11 - Refrigeration systems.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Refrigeration systems. 151.40-11 Section...Control Installations § 151.40-11 Refrigeration systems. (a) Boiloff systems... (b) Vapor compression, tank refrigeration, and secondary refrigeration...

2009-10-01

458

1998 ASHRAE Refrigeration Handbook addresses insulation for refrigeration systems  

SciTech Connect

Created through an ASHRAE subcommittee, Insulation Systems for Refrigeration Piping Systems chapter provides comprehensive guidelines for insulating refrigeration systems. The two articles that follow present a brief overview of this new chapter and design tips for engineers. The new insulation chapter in the 1998 ASHRAE Handbook only recommends closed-cell pipe and equipment insulation for refrigeration piping systems. It has been estimated that 98% of the problems with open-cell insulation systems are due to moisture. Moisture generally enters an insulation system through ineffective jacketing. Surprisingly, even insulation materials operating at high temperatures can retain extremely high quantities of water. A closed-cell insulation has outstanding resistance to liquid water and even water vapor, thereby providing the greatest operating efficiency over the life of the system.

Connolly, B. [Connolly Associates, New Market, MD (United States)

1997-09-01

459

Superinsulation in refrigerators and freezers  

SciTech Connect

The results presented here were obtained during Phase 4 of the first CRADA, which had the specific objective of determining the lifetime of superinsulations when installed in simulated refrigerator doors. The second CRADA was established to evaluate and test design concepts proposed to significantly reduce energy consumption in a refrigerator-freezer that is representative of approximately 60% of the US market. The stated goal of this CRADA is to demonstrate advanced technologies which reduce, by 50%, the 1993 National Appliance Energy Conservation Act (NAECA) standard energy consumption for a 20 ft{sup 3} (570 L) top-mount, automatic-defrost, refrigerator-freezer. For a unit this size, the goal translates to an energy consumption of 1.003 kWh/d. The general objective of the research is to facilitate the introduction of efficient appliances by demonstrating design changes that can be effectively incorporated into new products. In previous work on this project, a Phase 1 prototype refrigerator-freezer achieved an energy consumption of 1.413 kWh/d [Vineyard, et al., 1995]. Following discussions with an advisory group comprised of all the major refrigerator-freezer manufacturers, several options were considered for the Phase 2 effort, one of which was cabinet heat load reductions.

Vineyard, E.; Stovall, T.K.; Wilkes, K.E.; Childs, K.W.

1998-02-01

460

Air conditioning and refrigeration engineering  

SciTech Connect

This book supplies the basics of design, from selecting the optimum system and equipment to preparing the drawings and specifications. It discusses the four phases of preparing a project: gathering information, developing alternatives, evaluating alternatives, and selling the best solution. In addition, the author breaks down the responsibilities of the engineer design documents, computer aided design, and government codes and standards. It provides you with an easy reference to all aspects of the topic. This resource addresses the most current areas of interest, such as computer aided design and drafting, desiccant air conditioning and energy conservation. It is a thorough and convenient guide to air conditioning and refrigeration engineering. Contents include: introduction; psychrometrics; air-conditioning processes and cycles; refrigerants and refrigeration cycles; outdoor design conditions and indoor design criteria; load calculations; air handling units and packaged units; refrigeration components and evaporative coolers; water systems; heating systems; refrigeration systems; thermal storage system; air system basics; absorption systems; air-conditioning systems and selection; and desiccant dehumidification and air-conditioning.

Kreith, F. [ed.] [Univ. of Colorado, Boulder, CO (US)

1999-12-01

461

Experimental study of the inert effect of R134a and R227ea on explosion limits of the flammable refrigerants  

Microsoft Academic Search

Experimental studies of the inert effect of R134a and R227ea on explosive limits of the flammable refrigerants were carried out. The ranges of the explosive limits of the mixture of R134a, R227ea and other six flammable refrigerants of HFCs and HCs were obtained. The critical suppression explosive concentrations of these mixtures can be found from the envelopes. A model about

Yang Zhao; Liu Bin; Zhao Haibo

2004-01-01

462

Theoretical study of a transcritical ejector refrigeration cycle with refrigerant R143a  

Microsoft Academic Search

In this paper, a transcritical ejector refrigeration cycle (TERC) using refrigerant R143a as working fluid is proposed to improve the performance of the ejector refrigeration systems driven by low-grade thermal energy. This method adopts an adequate combination of thermal and mechanical energy through the operation of the transcritical process for generator to enhance the performance of the conventional ejector refrigeration

Jianlin Yu; Zhenxing Du

2010-01-01

463

Performance Monitoring in Supermarket Refrigeration Systems - Synchronization of Refrigerated Display Cases  

Microsoft Academic Search

The overall task of a supermarket refrigeration system is to maintain the quality of the foodstuff. This is done by making use of a refrigeration cycle in which a refrigerant transport heat from the refrigerated display-cases to the outdoor surroundings. Typically the system is equipped with a decentralized control system neglecting interactions between subsystems. Though these interactions are minor they

Liang Chen; Torben Green; Lars F. S. Larsen; Rafael Wisniewski; Roozbeh Izadi-Zamanabadi

464

Refrigeration system having improved heat transfer and reduce power requirement for various evaporative refrigerants  

Microsoft Academic Search

A description is given of an improved refrigerating system of the type which includes (A) an evaporator for circulating a fluid refrigerate therethrough to absorb heat from a refrigerating medium, whereby said medium is cooled and said refrigerant is converted from a liquid to a gas, (B) an oil lubricated compressor connected in receiving relation to said evaporator for compressing

1980-01-01

465

Thermoelectric refrigerator having improved temperature stabilization means  

DOEpatents

A control system for thermoelectric refrigerators is disclosed. The thermoelectric refrigerator includes at least one thermoelectric element that undergoes a first order change at a predetermined critical temperature. The element functions as a thermoelectric refrigerator element above the critical temperature, but discontinuously ceases to function as a thermoelectric refrigerator element below the critical temperature. One example of such an arrangement includes thermoelectric refrigerator elements which are superconductors. The transition temperature of one of the superconductor elements is selected as the temperature control point of the refrigerator. When the refrigerator attempts to cool below the point, the metals become superconductors losing their ability to perform as a thermoelectric refrigerator. An extremely accurate, first-order control is realized.

Falco, Charles M. (Woodridge, IL)

1982-01-01

466

Microprocessor controller for combination refrigerator-freezer.  

National Technical Information Service (NTIS)

A microprocessor-based controller for residential refrigerator-freezers with two independent refrigeration systems and automatic defrosting has been designed. A precise temperature control is achieved by applying the proportional integral regulator princi...

J. Schjaer-Jacobsen

1994-01-01

467

Vuilleumier Cycle Cryogenic Refrigeration System Technology Report.  

National Technical Information Service (NTIS)

The report presents a compact and comprehensive technical discussion of the Vuilleumier refrigerator technology that has evolved from a program to design, develop, and test three refrigeration systems (one for an infrared scanner system, one for an advanc...

B. S. Leo

1971-01-01

468

Refrigerator Thermometers: Cold Facts about Food Safety  

MedlinePLUS

... Selected Health Topics For Women Kids & Teens Refrigerator Thermometers: Cold Facts about Food Safety Available in PDF ( ... También disponible en español (Spanish). A Simple Refrigerator Thermometer Can Make a Big Difference When it comes ...

469

Modeling Supermarket Refrigeration with Energy Plus.  

National Technical Information Service (NTIS)

Supermarket refrigeration capabilities were first added to EnergyPlus in 2004. At that time, it was possible to model a direct expansion (DX) rack system with multiple refrigerated cases. The basic simulation software handles all the building energy uses,...

T. K. Stovall V. D. Baxter

2010-01-01

470

A review of absorption refrigeration technologies  

Microsoft Academic Search

This paper provides a literature review on absorption refrigeration technology. A number of research options such as various types of absorption refrigeration systems, research on working fluids, and improvement of absorption processes are discussed.

Pongsid Srikhirin; Satha Aphornratana; Supachart Chungpaibulpatana

2001-01-01

471

A review of pulse tube refrigeration  

NASA Technical Reports Server (NTRS)

This paper reviews the development of the three types of pulse tube refrigerators: basic, resonant, and orifice types. The principles of operation are given. It is shown that the pulse tube refrigerator is a variation of the Stirling-cycle refrigerator, where the moving displacer is substituted by a heat transfer mechanism or by an orifice to bring about the proper phase shifts between pressure and mass flow rate. A harmonic analysis with phasors is described which gives reasonable results for the refrigeration power, yet is simple enough to make clear the processes which give rise to the refrigeration. The efficiency and refrigeration power are compared with those of other refrigeration cycles. A brief review is given of the research being done at various laboratories on both one- and two-stage pulse tubes. A preliminary assessment of the role of pulse tube refrigerators is discussed.

Radebaugh, Ray

1990-01-01

472

REDUCING REFRIGERANT EMISSIONS FROM SUPERMARKET SYSTEMS  

EPA Science Inventory

Large refrigeration systems are found in several applications including supermarkets, cold storage warehouses, and industrial processes. The sizes of these systems are a contributing factor to their problems of high refrigerant leak rates because of the thousands of connections, ...

473

A two-degree Kelvin refrigerator  

NASA Technical Reports Server (NTRS)

Open-cycle cryogenic refrigerator maintains temperature as low as 2K for periods up to six months. Designed to cool an infrared detector, refrigerator can be used in cooling Josephson-junction devices, magnetic bubble domains, and superconducting devices.

Stephens, J. B.; Miller, C. G.

1975-01-01

474

Methods development for measuring and classifying flammability/combustibility of refrigerants. Final report  

SciTech Connect

Because of concerns for the effect that chlorofluorocarbon (CFC) fluids currently in use as refrigerants have on the environment, the refrigeration industry is considering the use of natural refrigerants, many of which are potentially flammable. In some cases, these flammable fluids may result in the least environmental damage when considering ozone depletion, global warming, efficiency, and photochemical reactivity. Many potentially flammable fluids have been proven to be effective when used either by themselves or as a part of a binary or ternary mixture. However, despite favorable initial test results, these fluids may not be acceptable to the general public if questions of safety cannot be adequately addressed. Significant research is being conducted to investigate the flammability of these materials. The purpose of this project is to experimentally determine the impact and variability of eleven different parameters which may affect flammability and/or combustibility of refrigerants and refrigerant blends, as a function of composition and test conditions, and to develop a better understanding of methods and conditions to measure the flammability of refrigerants. The refrigerants used in this study are being considered as new refrigerants and reviewed published data on these materials is scarce. The data contained herein should not be considered complete and should be used only to make relative comparisons of the impacts of the test parameters, not to represent the flammability characteristics of the materials. This report documents Task 3 of the test program. During Task 1, technical literature was thoroughly reviewed and a database of available documents was constructed. During Task 2, the test plan for this task was written. The goals of Task 3 are to investigate the flammability characteristics of selected blends of refrigerants R32, R134a, and R125 using an existing explosion sphere and a newly-constructed ASTM E681 apparatus.

Heinonen, E.W.; Tapscott, R.E.; Crawford, F.R. [Univ. of New Mexico, Albuquerque, NM (United States)

1994-12-01

475

Self-regulated energy saving refrigeration circuit  

SciTech Connect

A self-regulated refrigeration circuit incorporating a compressor/condenser guard device for cooling compressor refrigerant output prior to application to a condenser and for reevaporating liquid refrigerant discharged from the evaporators prior to its return to the compressor. A pressure differential chamber and high velocity suction line operate in conjunction with the compressor/condenser guard device to control refrigerant flow through the evaporators in both the freeze and defrost cycles of the circuit.

Aleksandrow, J.

1985-07-23

476

Cascade Joule-Thomson refrigerators  

SciTech Connect

The design criteria for cascade Joule-Thomson refrigerators for cooling in the temperature range from 300 K to 4.2 K were studied. The systems considered use three or four refrigeration stages with various working gases to achieve the low temperatures. Each stage results in cooling to a progressively lower temperature and provides cooling at intermediate temperatures to remove the substantial amount of parasitic heat load encountered in a typical dewar. With careful dewar design considerable cooling can be achieved with moderate gas flows. For many applications, e.g., in the cooling of sensitive sensors, the fact that the refrigerator contains no moving parts and may be remotely located from the gas source is of considerable advantage. A small compressor suitable for providing the gas flows required was constructed.

Tward, E.; Steyert, W.A.

1983-12-01

477

Observations of 1,1-difluoroethane (HFC-152a) at AGAGE and SOGE monitoring stations in 1994-2004 and derived global and regional emission estimates  

NASA Astrophysics Data System (ADS)

Ground-based in situ measurements of 1,1-difluoroethane (HFC-152a, CH3CHF2) which is regulated under the Kyoto Protocol are reported under the auspices of the AGAGE (Advanced Global Atmospheric Gases Experiment) and SOGE (System of Observation of halogenated Greenhouse gases in Europe) programs. Observations of HFC-152a at five locations (four European and one Australian) over a 10 year period were recorded. The annual average growth rate of HFC-152a in the midlatitude Northern Hemisphere has risen from 0.11 ppt/yr to 0.6 ppt/yr from 1994 to 2004. The Southern Hemisphere annual average growth rate has risen from 0.09 ppt/yr to 0.4 ppt/yr from 1998 to 2004. The 2004 average mixing ratio for HFC-152a was 5.0 ppt and 1.8 ppt in the Northern and Southern hemispheres, respectively. The annual cycle observed for this species in both hemispheres is approximately consistent with measured annual cycles at the same locations in other gases which are destroyed by OH. Yearly global emissions of HFC-152a from 1994 to 2004 are derived using the global mean HFC-152a observations and a 12-box 2-D model. The global emission of HFC-152a has risen from 7 Kt/yr to 28 Kt/yr from 1995 to 2004. On the basis of observations of above-baseline elevations in the HFC-152a record and a consumption model, regional emission estimates for Europe and Australia are calculated, indicating accelerating emissions from Europe since 2000. The overall European emission in 2004 ranges from 1.5 to 4.0 Kt/year, 5-15% of global emissions for 1,1-difluoroethane, while the Australian contribution is negligible at 5-10 tonnes/year, <0.05% of global emissions.

Greally, B. R.; Manning, A. J.; Reimann, S.; McCulloch, A.; Huang, J.; Dunse, B. L.; Simmonds, P. G.; Prinn, R. G.; Fraser, P. J.; Cunnold, D. M.; O'Doherty, S.; Porter, L. W.; Stemmler, K.; Vollmer, M. K.; Lunder, C. R.; Schmidbauer, N.; Hermansen, O.; Arduini, J.; Salameh, P. K.; Krummel, P. B.; Wang, R. H. J.; Folini, D.; Weiss, R. F.; Maione, M.; Nickless, G.; Stordal, F.; Derwent, R. G.

2007-03-01

478

Adsorbability of 1,1,1,2-Tetrafluoromethane (HFC134a) onto Plasma-Treated Activated Carbon in CF4 and CCl4  

PubMed

The adsorbability of 1,1,1,2-tetrafluoroethane (HFC134a), which has been the CFC12 replacement, onto tetrafluoromethane and tetrachloromethane plasma-treated activated carbon (FT-ACs and CT-ACs) was investigated. It is proved that the fluorine and the chlorine, which were produced by plasma treatment, were introduced into the pores having radii greater 7.5 A and with less than 7.5 A by plasma treatment, respectively. The adsorption site of HFC134a onto activated carbon may change with the quantities of fluorine or chlorine on the surface of the activated carbon. The amount of HFC134a adsorbed per unit specific surface area of FT-ACs and CT-ACs slightly increased a little compared to the untreated activated carbon (U-AC). The amount of fluoride ion eluted before the adsorption of HFC134a from the FT-ACs increased with the increasing plasma treatment time. That after the adsorption of HFC134a from only the activated carbon with the shortest plasma treatment time decreased. The amount of chloride ion eluted before the adsorption of HFC134a from the CT-ACs increased after 15 min of plasma treatment, but decreased with 30 min of plasma treatment. The chloride ion amount from the CT-ACs decreased after the adsorption of HCF134a. These results could be explained by the Langmuir constants a and Ws, which represent the adsorption equilibrium constant and the saturated amount of HFC134a adsorbed, respectively. The ratio of fluorine and chlorine species, the adsorption type, the layer interstitial type, and the covalent type, is different based on the plasma treatment time. It is concluded that the amount of HFC134a adsorbed onto the FT-ACs and CT-ACs did not depend upon the change of pore structure by the fluorine and chlorine. PMID:9268515

Tanada; Kawasaki; Nakamura; Ohue; Abe

1997-07-15

479

Adsorbability of 1,1,1,2-tetrafluoromethane (HFC134a) onto plasma-treated activated carbon in CF{sub 4} and CCl{sub 4}  

SciTech Connect

The adsorbability of 1,1,1,2-tetrafluoroethane (HFC134a), which has been the CFC12 replacement, onto tetrafluoromethane and tetrachloromethane plasma-treated activated carbon (FT-ACs and CT-ACs) was investigated. It is proved that the fluorine and the chlorine, which were produced by plasma treatment, were included into the pores having radii greater than 7.5 {angstrom} and with less than 7.5 {angstrom} by plasma treatment, respectively. The adsorption site of HFC134a onto activated carbon may change with the quantities of fluorine or chlorine on the surface of the activated carbon. The amount of HFC134a adsorbed per unit specific surface area of FT-ACs and CT-ACs slightly increased a little compared to the untreated activated carbon (U-AC). The amount of fluoride ion eluted before the adsorption of HFC134a from the FT-ACs increased with the increasing plasma treatment time. That after the adsorption of HFC134a from only the activated carbon with the shortest plasma treatment time decreased. The amount of chloride ion eluted before the adsorption of HFC134a from the CT-ACs increased after 15 min of plasma treatment, but decreased with 30 min of plasma treatment. The chloride ion amount from the CT-ACs decreased after the adsorption of HCF134a. These results could be explained by the Langmuir constants a and Ws, which represent the adsorption equilibrium constant and the saturated amount of HFC134a adsorbed, respectively. The ratio of fluorine and chlorine species, the adsorption type, the layer interstitial type, and the covalent type, is different based on the plasma treatment time. It is concluded that the amount of HFC134a adsorbed onto the FT-ACs and CT-ACs did not depend upon the change of pore structure by the fluorine and chlorine.

Tanada, Seiki; Kawasaki, Naohito; Nakamura, Takeo; Ohue, Takashi [Kinki Univ., Higashi, Osaka (Japan). Faculty of Pharmaceutical Sciences] [Kinki Univ., Higashi, Osaka (Japan). Faculty of Pharmaceutical Sciences; Abe, Ikuo [Osaka Municipal Technical Research Inst., Osaka (Japan)] [Osaka Municipal Technical Research Inst., Osaka (Japan)

1997-07-15

480

21 CFR 1250.34 - Refrigeration equipment.  

Code of Federal Regulations, 2011 CFR

...and Drugs 8 2011-04-01 2011-04-01 false Refrigeration equipment. 1250.34 Section 1250.34 Food and Drugs...on Land and Air Conveyances, and Vessels § 1250.34 Refrigeration equipment. Each refrigerator shall be equipped with...

2011-04-01

481

21 CFR 1250.34 - Refrigeration equipment.  

Code of Federal Regulations, 2010 CFR

...and Drugs 8 2010-04-01 2010-04-01 false Refrigeration equipment. 1250.34 Section 1250.34 Food and Drugs...on Land and Air Conveyances, and Vessels § 1250.34 Refrigeration equipment. Each refrigerator shall be equipped with...

2010-04-01

482

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

Gschneidner, Jr., Karl A. (Ames, IA); Takeya, Hiroyuki (Ibaraki, JP)

1995-07-25