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1

Two-Phase Cooling Method Using the R134a Refrigerant to Cool Power Electronic Devices  

Microsoft Academic Search

This paper presents a two-phase cooling method using the R134a refrigerant to dissipate the heat energy (loss) generated by power electronics (PEs), such as those associated with rectifiers, converters, and inverters for a specific application in hybrid-electric vehicles. The cooling method involves submerging PE devices in an R134a bath, which limits the junction temperature of PE devices while conserving weight

Jeremy B. Campbell; Leon M. Tolbert; Curtis William Ayers; Burak Ozpineci; Kirk T. Lowe

2007-01-01

2

Two-phase cooling method using R134a refrigerant to cool power electronic devices  

Microsoft Academic Search

This paper presents a two-phase cooling method using R134a refrigerant to dissipate the heat energy (loss) generated by power electronics (PE) such as those associated with rectifiers, converters, and inverters for a specific application in hybrid-electric vehicles (HEVs). The cooling method involves submerging PE devices in an R134a bath, which limits the junction temperature of PE devices while conserving weight

Jeremy B. Campbell; Leon M. Tolbert; Curt W. Ayers; Burak Ozpineci

2005-01-01

3

Floating Refrigerant Loop Based on R-134a Refrigerant Cooling of High-Heat Flux Electronics  

SciTech Connect

The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) have been developing technologies to address the thermal issues associated with hybrid vehicles. Removal of the heat generated from electrical losses in traction motors and their associated power electronics is essential for the reliable operation of motors and power electronics. As part of a larger thermal control project, which includes shrinking inverter size and direct cooling of electronics, ORNL has developed U.S. Patent No. 6,772,603 B2, ''Methods and Apparatus for Thermal Management of Vehicle Systems and Components'' [1], and patent pending, ''Floating Loop System for Cooling Integrated Motors and Inverters Using Hot Liquid Refrigerant'' [2]. The floating-loop system provides a large coefficient of performance (COP) for hybrid-drive component cooling. This loop (based on R-134a) is integrated with a vehicle's existing air-conditioning (AC) condenser, which dissipates waste heat to the ambient air. Because the temperature requirements for cooling of power electronics and electric machines are not as low as that required for passenger compartment air, this adjoining loop can operate on the high-pressure side of the existing AC system. This arrangement also allows the floating loop to run without the need for the compressor and only needs a small pump to move the liquid refrigerant. For the design to be viable, the loop must not adversely affect the existing system. The loop should also provide a high COP, a flat-temperature profile, and low-pressure drop. To date, the floating-loop test prototype has successfully removed 2 kW of heat load in a 9 kW automobile passenger AC system with and without the automotive AC system running. The COP for the tested floating-loop system ranges from 40-45, as compared to a typical AC system COP of about 2-4. The estimated required waste-heat load for future hybrid applications is 5.5 kW and the existing system could be easily scaleable for this larger load.

Lowe, K.T.

2005-10-07

4

A solar ejector cooling system using refrigerant R134a in the Athens area  

Microsoft Academic Search

This paper describes the performance of an ejector cooling system driven by solar energy and R134a as working fluid. The system operating in conjunction with intermediate temperature solar collector in Athens, is predicted along the 5 months (May–September). The operation of the system and the related thermodynamics are simulated by suitable computer codes and the required local climatologically data are

G. K. Alexis; E. K. Karayiannis

2005-01-01

5

Experimental investigation on R134a vapour ejector refrigeration system  

Microsoft Academic Search

The experimental investigation of the performance of a vapour ejector refrigeration system is described. The system uses R134a as working fluid and has a rated cooling capacity of 0.5kW. The influence of generator, evaporator and condenser temperatures on the system performance is studied. This kind of system can be operated with low grade thermal energy such as solar energy, waste

A. Selvaraju; A. Mani

2006-01-01

6

Absorption system based on the refrigerant R134a  

Microsoft Academic Search

The possibility of using 1,1,1,2-tetrafluoroethane (R134a) as a refrigerant in combination with different organic absorbents, such as dimethylether tetraethyleneglycol (DMETEG), N-methyl ?-caprolactam (MCL) or dimethyl-ethyleneurea (DMEU), in absorption units was investigated. The procedures in this paper are presented for the model working pair R134a-DMETEG. Temperature-pressure-concentration curves were constructed on the basis of vapour-liquid equilibrium measurements. Excess thermodynamic properties of the

I Borde; M Jelinek; N. C Daltrophe

1995-01-01

7

Using R-134a and R-22 in supermarket refrigeration applications  

Microsoft Academic Search

This article reports on tests of the performance of refrigerants R-134a and R-22 in medium and low temperature refrigeration systems. These tests were performed to determine the accuracy of predictions that R-134a would be a suitable replacement for CFC refrigerants in supermarkets. The testing resulted in extensive modifications to compressors, lubricating oil and control systems while using standard piping systems,

R. H. Albrecht; H. Borhanian; L. J. Rafuse; T. J. Matthews

1994-01-01

8

Using R-134a and R-22 in supermarket refrigeration applications  

SciTech Connect

This article reports on tests of the performance of refrigerants R-134a and R-22 in medium and low temperature refrigeration systems. These tests were performed to determine the accuracy of predictions that R-134a would be a suitable replacement for CFC refrigerants in supermarkets. The testing resulted in extensive modifications to compressors, lubricating oil and control systems while using standard piping systems, expansion valves and installation practices.

Albrecht, R.H. (New York State Energy Research and Development Authority, Albany, NY (United States)); Borhanian, H.; Rafuse, L.J. (Aspen Systems Inc., Marlborough, MA (United States)); Matthews, T.J. (Hannaford Bros., Co., Scarborough, ME (United States))

1994-02-01

9

Accurate adsorption isotherms of R134a onto activated carbons for cooling and freezing applications  

Microsoft Academic Search

The objective of this article is to improve the performance of thermally powered adsorption\\/cooling systems by selecting a new adsorbent\\/refrigerant pair. Adsorption equilibrium data of R134a onto granular activated carbon (AC) and Unitika activated carbon fiber (ACF) of type (A-20) have been measured experimentally using Rubotherm ISOSORP 2000 within evaporation temperatures range between ?20 and 40 °C and adsorption temperatures range

Bidyut Baran Saha; Ibrahim I. El-Sharkawy; Roger Thorpe; Robert E. Critoph

10

The viscosity of R134a refrigerant in the gas phase  

SciTech Connect

Experimentally obtained values are presented for the dynamic viscosity of the R134a gaseous refrigerant in a little-studied range of parameters. A comparison is made with available experimental data on supercritical isotherms and with known analytic dependences.

Pasekov, M.F.; Ustyuzhanin, E.E. [Moscow Power Institute, Moscow (Russian Federation)

1994-07-01

11

Condensation heat transfer and pressure drop of refrigerant R-134a in a small pipe  

Microsoft Academic Search

The characteristics of condensation heat transfer and pressure drop for refrigerant R-134a flowing in a horizontal small circular pipe that has an inside diameter of 2.0 mm were investigated experimentally in this study. The effects of the heat flux, mass flux, vapor quality and saturation temperature of R-134a on the measured condensation heat transfer and pressure drop were examined in

Yi-Yie Yan; Tsing-Fa Lin

1999-01-01

12

Evaporation heat transfer and pressure drop of refrigerant R-134a in a small pipe  

Microsoft Academic Search

An experiment was carried out to investigate the characteristics of the evaporation heat transfer and pressure drop for refrigerant R-134a flowing in a horizontal small circular pipe having an inside diameter of 2.0 mm. The data are useful in designing more compact and effective evaporators for various refrigeration and air conditioning systems. The effects of the imposed wall heat flux,

Yi-Yie Yan; Tsing-Fa Lin

1998-01-01

13

Thermal conductivity of refrigerants R123, R134a, and R125 at low temperatures  

Microsoft Academic Search

Using a transient coaxial cylinder technique, thermal conductivities were measured for liquid 1,1,1-trifluoro-2,2-dichloroethane (refrigerant R123), 1,1,1,2-tetrafluoroethane (refrigerant R134a). and pentalluoroethane (refrigerant R 125). The uncertainty of the experimental data is estimated to be within 2–3 %. Thermal conductivities of refrigerants were measured at temperatures ranging from -114 to 20°C under pressures up to IOMPa. The apparatus was calibrated with four

O. B. Tsvetkov; Yu. A. Laptev; A. G. Asambaev

1994-01-01

14

Pilot retrofit test of refrigerant R-134a for GDSCC  

NASA Technical Reports Server (NTRS)

NASA has issued an interim policy requiring all of its Centers to eliminate consumption (purchase) of stratospheric ozone-depleting substances, including chlorofluorocarbons (CFC's), by 1995. Also, plans must be outlined for the eventual phase out of their usage. The greatest source of CFC consumption and usage at the Goldstone Deep Space Communications Complex is refrigerant R-12, which is used in many of the facility's air-conditioning systems. A pilot retrofit test shows that retrofitting R-12 air-conditioning systems with hydrofluorocarbon R-13a would be a workable means to comply with the R-12 portion of NASA's policy. Results indicate acceptable cost levels and nearly equivalent system performance.

Albus, J.; Brown, B.; Dungao, M.; Spencer, G.

1994-01-01

15

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

16

Experimental studies on R134a-DMAC hot water based vapour absorption refrigeration systems  

Microsoft Academic Search

The objective of this paper is to present an experimental study on environment friendly vapour absorption refrigeration system of 1 kW capacity using R134a-DMAC as the working fluids. The system is designed and tested for various operating conditions using hot water as heat source. In this paper, performance of the fabricated system are outlined with respect to various operating parameters

V. Muthu; R. Saravanan; S. Renganarayanan

2008-01-01

17

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

18

Thermal conductivity and thermal diffusivity of the R134a refrigerant in the liquid state  

NASA Astrophysics Data System (ADS)

Thermal conductivity and thermal diffusivity of “ozone-safe” refrigerant R134a in liquid state within the range of temperatures 295.9-354.9 K and pressures from the liquid — vapor equilibrium line up to 4.08 MPa have been studied by high-frequency thermal-wave method. The experimental uncertainties of the temperature, pressure, thermal conductivity and thermal diffusivity measurement errors were estimated to be 0.1 K, 3 kPa, 1.5 and 2.5 %, respectively. Values of thermal conductivity and thermal diffusivity of liquid R134a on saturated line have been calculated. Approximation dependences for thermal conductivity and thermal diffusivity within the whole studied range of temperatures and pressures as well as on the saturated line have been obtained.

Baginsky, A. V.; Shipitsyna, A. S.

2009-06-01

19

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

20

Effect of Fin Geometry on Condensation Heat Transfer of Refrigerant R134a on Enhanced Finned Tubes  

NASA Astrophysics Data System (ADS)

This paper presents the experimental results on the outside condensation heat tral1sfer coefficient of horizontal enhanced filmed tubes. Three different fin geometry types of three-dimensional enhanced finned tubes were tested. A low-fin-tube (LFT) 19 fin-per-inch (fpi) was also tested for reference. Experimental refrigerant used was R134a. The heat tral1sfer coefficient test was carried out at a condensing temperature of 40°C, at a cooling water velocity of 1.5 m/s, and the heat flux of 10 to 110 kW/m2K. The outside condensation heat transfer coefficient of all three dimensional enhanced finned tubes were approximately 1.9 times higher than that of LFTl9fpi at high heat flux range. In low heat flux range, the enhanced finned tube of small circumferential segmentation pitches at the fin tip was shown the highest outside heat transfer coefficient for all tubes tested.

Takahashi, Hiroyuki; Saeki, Chikara; Koyama, Shigeru

21

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

22

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

23

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

Microsoft Academic Search

This paper presents the experimental heat transfer coefficients and pressure drop measured during refrigerant R134a vaporisation inside a small brazed plate heat exchanger (BPHE): the effects of heat flux, refrigerant mass flux, saturation temperature and outlet conditions are investigated. The BPHE tested consists of 10 plates, 72mm in width and 310mm in length, which present a macro-scale herringbone corrugation with

G. A. Longo; A. Gasparella

2007-01-01

24

Effect of refrigerant oil additive on R134a and R123 boiling heat transfer performance  

Microsoft Academic Search

This paper investigates the effect that an additive had on the boiling performance of an R134a\\/polyolester lubricant (POE) mixture and an R123\\/naphthenic mineral oil mixture on a roughened, horizontal flat surface. Both pool boiling heat transfer data and lubricant excess surface density data are given for the R134a\\/POE (98% mass fraction\\/2% mass fraction) mixture before and after use of the

M. A. Kedzierski

2007-01-01

25

An experimental study on condensation of refrigerant R134a in a multi-port extruded tube  

Microsoft Academic Search

In the present study, the local characteristics of pressure drop and heat transfer are investigated experimentally for the condensation of pure refrigerant R134a in two kinds of 865 mm long multi-port extruded tubes having eight channels in 1.11 mm hydraulic diameter and 19 channels in 0.80 mm hydraulic diameter. The pressure drop is measured at an interval of 191 mm

Shigeru Koyama; Ken Kuwahara; Kouichi Nakashita; Ken Yamamoto

2003-01-01

26

Experimental studies on heat and mass transfer performance of a coiled tube absorber for R134a-DMAC based absorption cooling system  

NASA Astrophysics Data System (ADS)

Absorber is an important component in vapor absorption refrigeration system and its performance has greater influence in overall efficiency of absorption machines. Falling film heat and mass transfer in an absorber is greatly influenced by fluid properties, geometry of heat exchanger and its operating parameters. This paper presents on the results of experimental studies on the heat and mass transfer characteristics of a coiled tube falling film absorber, using 1,1,1,2-Tetrafluroethane(R-134a) and N-N Dimethyl Acetamide (DMAC) as working fluids. The effects of film Reynolds number, inlet solution temperature and cooling water temperature on absorber heat load, over all heat transfer coefficient and mass of refrigerant absorbed are presented and discussed. Normalized solution and coolant temperature profiles and refrigerant mass absorbed along the height of absorber are also observed from the experimental results. The optimum over all heat transfer coefficient for R-134a DMAC solution found to be 726 W/m2K for a film Reynolds number of 350. The R-134a vapour absorption rate is maximum in the normalized coil height of 0.6 to 1.

Mohideen, S. Tharves; Renganarayanan, S.

2008-04-01

27

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

28

Two-phase flow regimes in round, square and rectangular tubes during condensation of refrigerant R134a  

Microsoft Academic Search

An experimental investigation of two-phase flow mechanisms during condensation of refrigerant R134a in six small diameter round (4.91 mm), square (Dh=4 mm, ?=1), and rectangular (4×6 and 6×4 mm: Dh=4.8 mm, ?=0.67 and 1.5; 2×4 and 4×2 mm: Dh=2.67 mm, ? =0.5 and 2) was conducted. Unique experimental techniques and test sections were developed to enable the documentation of the

John W Coleman; Srinivas Garimella

2003-01-01

29

Evaporation heat transfer and pressure drop of refrigerant R-134a in a plate heat exchanger  

Microsoft Academic Search

Plate heat exchangers (PHE) have been widely used in food processing, chemical reaction processes, and other industrial applications for many years. Particularly, in the last 20 years plate heat exchangers have been introduced to the refrigeration and air conditioning systems as evaporators or condensers for their high efficiency and compactness. Here, the evaporation heat transfer coefficient and pressure drop for

Y.-Y. Yan; T.-F. Lin

1999-01-01

30

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

31

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

32

Thermal conductivity of the new refrigerants R134a, R152a, and R123 measured by the transient hot-wire method  

Microsoft Academic Search

Thermal-conductivity measurements are reported for the new refrigerants R134a, R152a und R123. Transient hot-wire experiments were performed which cover both the liquid and vapor states at temperatures and pressures ranging from?=-20°C to 90°C and fromp=0.1 bar to 60 bar respectively. The results are correlated with density and temperature. In addition temperature dependent correlations are presented for (i) saturated liquid, (ii)

U. Gross; Y. W. Song; E. Hahne

1992-01-01

33

Equation of state and thermodynamic properties of 1,1,1,2-tetrafluoroethane (refrigerant R134a)  

NASA Astrophysics Data System (ADS)

An equation of state and tables of thermodynamic properties of R134a in the saturation state and in the one-phase region are obtained in the temperature interval 320 500 K at pressures ranging from 0.01 to 7.5 MPa.

Vas'kov, E. T.

1995-01-01

34

Equation of state and thermmodynamic properties of 1,1,1,2-tetrafluoroethane (refrigerant R134a)  

SciTech Connect

An equation of state and tables of thermodynamic properties of R134a in the saturation state and in the one-phase region are obtained in the temperature interval 320-500 K at pressures ranging from 0.01 to 7.5 MPa.

Vas`kov, E.T. [St. Petersburg State Univ. of Architecture and Civil Engineering (Russian Federation)

1995-08-01

35

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

36

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

37

Critical Heat Flux near the Critical Pressure in Heater Rod Bundle Cooled by R-134a Fluid: Effects of Unheated Rods and Spacer Grid  

Microsoft Academic Search

In the development of supercritical pressure water cooled reactors, it is important to understand the characteristics of a heat transfer near the thermodynamic critical point. An experimental study on a critical heat flux near the critical pressure has been performed with a 5x5 square array heater rod bundle cooled by R-134a fluid. The critical power has been accurately measured up

Se-Young Chun; Chan-Hwan Shin; Sung-Deok Hong; Sang-Ki Moon

38

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

39

Experimental investigations into the impact of the void fraction on the condensation characteristics of R134a refrigerant in minichannels under conditions of periodic instability  

NASA Astrophysics Data System (ADS)

This paper present the results of experimental investigations of condensation of R134a refrigerant in pipe minichannels with internal diameters 0.64, 0.90, 1.40, 1.44, 1.92 and 3.30 mm subject to periodic pressure instabilities. It was established that as in conventional channels, the displacement velocity of the pressure instabilities distinctly depends on the frequency of their hydrodynamic generation. The void fraction distinctly influences the velocity of the pressure instabilities. The form of this relationship depends on the internal diameter of the minichannels and on the method of calculating the void fraction.

Kuczy?ski, Waldemar; Charun, Henryk

2011-08-01

40

Application of a new selection algorithm to the development of a wide-range equation of state for refrigerant R134a  

SciTech Connect

Refrigerants R134a (1,1,1,2-tetrafluoroethane) is a leading substitute for refrigerant R12. As such, there has been worldwide activity to develop accurate wide-range equations of state for this fluid. In this study, we have developed a new selection algorithm for determining high-accuracy equations of state in the Helmholtz representation. This method combines least-squares regression analysis with simulated annealing optimization. Simulated annealing, unlike stepwise regression, allows for the controlled acceptance of random increases in the objective function. Thus, this procedure produces a computationally efficient selection algorithm which is not susceptible to the function-space local-minima problems present in a purely stepwise regression approach. Two equations are presented in this work and compared against experimental data and other high-accuracy equations of state for R134a. One equation was produced strictly by using stepwise a regression algorithm, while the other was produced using the simulated-annealing selection algorithm. In both cases the temperature dependence of the equations was restricted to have no terms whose exponents were greater than five.

Shubert, K.B.; Ely, J.F. [Colorado School of Mines, Golden, CO (United States)

1995-01-01

41

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

42

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

43

Comparative study of cryogen spray cooling with R-134a and R-404a: implications for laser treatment of dark human skin  

NASA Astrophysics Data System (ADS)

Cutaneous laser treatment in dark skin patients is challenging due to significant light absorption by the melanin at the basal layer of epidermis, which can result in irreversible nonspecific thermal injury to the epidermis. Cryogen spray cooling (CSC) with R-134a (boiling point ? -26.2°C at 1 atm), which is currently used during cutaneous laser treatment, has shown poor efficacy in protecting dark human skin. We investigated the potential of CSC with R-404a (boiling point ? -46.5°C at 1 atm), which has a lower boiling point than R-134a, for improved therapeutic outcome in dark human skin at three levels: in vitro (epoxy resin skin phantom), ex vivo (normal dark human skin sample), and in vivo (skin of the rabbit external ear). The skin phantom was used to acquire the surface and internal temperature profiles in response to CSC with R-134a or R-404a at various spurt durations, based upon which CSC-induced heat removal from the skin phantom was estimated using an algorithm that solved a one-dimensional inverse heat conduction problem. CSC with R-404a increased the temperature reductions within the phantom and subsequently the amount of heat removal from the phantom in comparison to that with R-134a. Normal ex vivo Fitzpatrick types V-VI human skin samples were used to investigate the thermal response of dark human skin epidermis to CSC (R-134a or R-404a) at various spurt durations in conjunction with 595-nm pulsed dye laser irradiation at various radiant exposures. Cryogen R-404a increased the threshold radiant exposures for irreversible thermal injury to the epidermis in dark pigmentation skin. No obvious CSC-induced morphological changes to human skin was observed when sprayed with R404-a spurts using durations up to 300 ms. In vivo rabbit ear vasculature was used as a model of cutaneous anomalies to assess the influences of CSC (with R-134a or R-404a) on the photothermolysis of dermal blood vessels. CSC (R-134a or R-404a) with the spurt durations of 100 to 300 ms increased the most superficial depth of thermally damaged dermal blood vessel compared with the sites without CSC, implying possible nonspecific cooling of superficial dermal blood vessels by the cryogen spurts with the settings applied.

Dai, Tianhong; Yaseen, Mohammad A.; Diagaradjane, Parmeswaran; Chang, David W.; Anvari, Bahman

2006-07-01

44

Thermal conductivity of the new refrigerants R134a, R152a, and R123 measured by the transient hot-wire method  

SciTech Connect

Thermal-conductivity measurements are reported for the new refrigerants R134a, R152a und R123. Transient hot-wire experiments were performed which cover both the liquid and vapor states at temperatures and pressures ranging from [theta] = [minus]20[degrees]C to 90[degrees]C and from p = O.1 bar to 60 bar respectively. The results are correlated with density and temperature. In addition temperature dependent correlations are presented for (1) saturated liquid, (2) saturated vapor, (3) ideal gas (which equals approximately vapor state at ambient pressure). Finally the results are compared with data from the literature and also with the thermal conductivities of R12 and R11. 35 refs., 14 figs., 8 tab.

Gross, U.; Song, Y.W.; Hahne, E. (Universitaet Stuttgart (Germany))

1992-01-01

45

Roughness and surface material effects on nucleate boiling heat transfer from cylindrical surfaces to refrigerants R-134a and R-123  

SciTech Connect

This paper presents results of an experimental investigation carried out to determine the effects of the surface roughness of different materials on nucleate boiling heat transfer of refrigerants R-134a and R-123. Experiments have been performed over cylindrical surfaces of copper, brass and stainless steel. Surfaces have been treated by different methods in order to obtain an average roughness, Ra, varying from 0.03 {mu}m to 10.5 {mu}m. Boiling curves at different reduced pressures have been raised as part of the investigation. The obtained results have shown significant effects of the surface material, with brass being the best performing and stainless steel the worst. Polished surfaces seem to present slightly better performance than the sand paper roughened. Boiling on very rough surfaces presents a peculiar behavior characterized by good thermal performance at low heat fluxes, the performance deteriorating at high heat fluxes with respect to smoother surfaces. (author)

Jabardo, Jose M. Saiz [Escuela Politecnica Superior, Universidad de la Coruna, Mendizabal s/n Esteiro, 15403 Ferrol, Coruna (Spain); Ribatski, Gherhardt; Stelute, Elvio [Department of Mechanical Engineering, Escola de Engenharia de Sao Carlos (EESC), University of Sao Paulo (USP), Av. Trabalhador Saocarlense 400 Centro, 13566-590 Sao Carlos, SP (Brazil)

2009-04-15

46

Dimensional analysis on the evaporation and condensation of refrigerant R-134a in minichannel plate heat exchangers  

Microsoft Academic Search

Two-phase flow analysis for the evaporation and condensation of refrigerants within the minichannel plate heat exchangers is an area of ongoing research, as reported in the literatures reviewed in this article. The previous studies mostly correlated the two-phase heat transfer and pressure drop in these minichannel heat exchangers using theories and empirical correlations that had previously been established for two-phase

Amir Jokar; Mohammad H. Hosni; Steven J. Eckels

2006-01-01

47

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

48

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

49

Effect of Refrigerant Oil Additive on R134a and R123 Boiling Heat Transfer Performance and Related Issues for GSA.  

National Technical Information Service (NTIS)

The paper investigates the effect that an additive had on the boiling performance of an R134a/polyolester lubricant (POE) mixture and an R123/naphthenic mineral oil mixture on a roughened, horizontal flat surface. Both pool boiling heat transfer data and ...

M. A. Kedzierski

2004-01-01

50

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

Microsoft Academic Search

One hundred ninety-three speed-of-sound values in gaseous difluoromethane (R-32, CHâFâ) + 1,1,1,2-tetrafluoroethane (R-134a, CFâCHâF) 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

Tsutomu Hozumi; Haruki Sato; Koichi Watanabe

1997-01-01

51

Experimental Performance of R-12234yf and R-1234ze as Drop-in Replacements for R-134a in Domestic Refrigerators.  

National Technical Information Service (NTIS)

Concerns about anthropogenic climate change have generated an interest in low global warming potential (GWP) refrigerants and have spawned policies and regulations that encourage the transition to low GWP refrigerants. Recent research has largely focused ...

E. A. Vineyard K. M. Karber O. Abdelaziz

2012-01-01

52

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

53

Experimental Study of the Flow of R-134a Through an Adiabatic Helically Coiled Capillary Tube  

Microsoft Academic Search

An experimental investigation was carried out to evaluate the flow characteristics of refrigerant R-134a through an adiabatic helically coiled capillary tube. The effect of various physical parameters like diameter and length of capillary tube, coil pitch, and inlet subcooling on the mass flow rate of R-134a was investigated. Moreover, the refrigerant mass flow rate through an instrumented capillary tube was

Mohd. Kaleem Khan; Ravi Kumar; Pradeep K. Sahoo

2008-01-01

54

Fundamentals of a Floating Refrigerant Loop Concept Based on R-134a Refrigerant Cooling of High Heat Flux Electronics  

Microsoft Academic Search

The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) has been developing technologies to address the thermal issues associated with hybrid vehicles. Removal of the heat generated from electrical losses in traction motors and their associated electronics, is essential for the reliable operation of motors and power electronics. As part of a larger thermal management

C. W. Ayers; J. S. Hsu; K. T. Lowe

55

The viscosity of liquid R134a  

SciTech Connect

The paper reports new measurements of the viscosity of liquid R134a over the temperature range 235 to 343 K and pressures up to 50 MPa. The measurements have been carried out in a vibrating-wire viscometer calibrated with respect to the viscosity of several liquid hydrocarbons. It is estimated that the uncertainty in the viscosity data reported is [+-]0.6%. The data therefore have a lower uncertainty than that of earlier measurements of the viscosity of this environmentally acceptable refrigerant. The viscosity data have been represented as a function of density by means of a formulation based upon the rigid, hard-sphere theory of dense fluids with a maximum deviation of [+-]0.3%. This representation allows the present body of experimental data to be extended to regions of thermodynamic state not covered by the measurements.

Oliveira, C.M.B.P.; Wakeham, W.A. (Imperial College, London (United Kingdom))

1993-01-01

56

Experimental studies on heat and mass transfer performance of a coiled tube absorber for R134a-DMAC based absorption cooling system  

Microsoft Academic Search

Absorber is an important component in vapor absorption refrigeration system and its performance has greater influence in overall\\u000a efficiency of absorption machines. Falling film heat and mass transfer in an absorber is greatly influenced by fluid properties,\\u000a geometry of heat exchanger and its operating parameters. This paper presents on the results of experimental studies on the\\u000a heat and mass transfer

S. Tharves Mohideen; S. Renganarayanan

2008-01-01

57

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

58

The effect of refrigerant combinations on performance of a vapor compression refrigeration system with dedicated mechanical sub-cooling  

Microsoft Academic Search

Performance characteristics due to use of different refrigerant combinations in vapor compression cycles with dedicated mechanical sub-cooling are investigated. For scratch designs, R134a used in both cycles produced the best results in terms of COP, COP gain and relative compressor sizing. In retrofit cases, considering the high sensitivity of COP to the relative size of heat exchangers in the sub-cooler

Bilal Ahmed Qureshi; Syed M. Zubair

59

Effect of void fraction models on the two-phase friction factor of R134a during condensation in vertical downward flow in a smooth tube  

Microsoft Academic Search

The void fraction of R134a condensing inside a vertical smooth tube is experimentally investigated in this study. The vertical test section is a 0.5 m long countercurrent flow double tube heat exchanger with refrigerant flowing down the inner tube and cooling water flowing upward in the annulus. The inner tube is made from smooth copper tubing and has an 8.1 mm inner

A. S. Dalkilic; S. Laohalertdecha; S. Wongwises

2008-01-01

60

Formation of gas hydrate with CFC alternative R-134a  

SciTech Connect

Gas hydrates are a class of solids, in which molecules of various compounds (guest species) are enclosed in icelike lattices that are made of hydrogen-bonded water molecules. Some CFC's (chlorofluorocarbons) such as R 11 (trichlorotrifluoromethane; CCl/sub 3/F) and R-12 (dichlorodifluoromethane, CCl/sub 2/F/sub 2/) are known to form gas hydrates, serving as guest species, which can exist at temperatures up to about 281.6 and 285.2 {Kappa}, respectively. The R-11 and R-12 hydrates had been considered the most favorable substances as cool storage media for residential air conditioning systems till restrictions on the use of CFC's became increasingly tight. R-134a (1,1,1,2-tetrafluoroethane, CF/sub 3/CH/sub 2/F) is currently considered a prospective substitute for R-12. In the present work, the authors explore if R-134a can form a gas hydrate and, if it can, to determine, with a reasonable accuracy for practical purpose, the highest temperature at which the hydrate can exist, i.e., the temperature of the quadruple point where the hydrate, R-134a in both vaporous and liquid states, and water in liquid state would coexist.

Mori, Y.H.; Mori, T. (Keio Univ., Yokohama (Japan))

1989-07-01

61

The viscosity of liquid R134a  

Microsoft Academic Search

The paper reports new measurements of the viscosity of liquid R134a over the temperature range 235 to 343 K and pressures up to 50 MPa. The measurements have been carried out in a vibrating-wire viscometer calibrated with respect to the viscosity of several liquid hydrocarbons. It is estimated that the uncertainty in the viscosity data reported is ±0.6%. The data

C. M. B. P. Oliveira; W. A. Wakeham

1993-01-01

62

Study of heat pump performance using mixtures of R32/R134A and R32/R125/R134A as drop-in' working fluids for R22 with and without a liquid-suction heat exchanger  

SciTech Connect

A ductless mini-split residential heat pump with a modified indoor coil was utilized to compare the performance of R22 and a mixture of 34% R32/66% R134a by weight. This test was intended to serve as an indicator of 'drop-in' performance so the system was optimized for each refrigerant by varying only the charge mass and expansion valve setting. At the 27.8 C (82 F) cooling test condition the capacity and COP of the mixture were 94% and 90% of the values for R22, respectively. Additional tests were conducted with a liquid-suction intracycle heat exchanger. The modified system was operated with both single-phase and two-phase refrigerant entering the low pressure side of the liquid-suction heat exchanger. The addition of the liquid-suction heat exchanger showed a minimal performance improvement with the performance of the two-phase variation being slightly higher. The best performing liquid-suction heat exchanger variant (two-phase refrigerant on the low pressure side) was also run with a ternary mixture of 30% R32/10% R125/60% R134a, by weight. The results for this mixture were similar to the binary mixture.

Rothfleisch, P.I.; Didion, D.A.

1993-12-01

63

Modelling of plate finned tube evaporators and condensers working with R134A  

Microsoft Academic Search

A model to predict the behaviour of finned tube evaporators and condensers working with R134a has been developed. For modelling of the refrigerant phase change, evaporation or condensation, the heat transfer and the pressure drop for the two-phase flow have to be calculated. Therefore, a number of correlations, the most recommended ones in the reviewed literature, have been analysed and

JoséM Corberán; Mónica García Melón

1998-01-01

64

Comparison of R744 and R134a heat transfer coefficients during flow boiling in a horizontal circular smooth tube  

Microsoft Academic Search

In last and recent years new regulamentations and p rotocols concerning the environmental impact of ref rigerants have led to the research of new environmental friendly refrigerants. In this contest the carbon dioxide (R744) is considered as one of the most promising substitute of the actually most widely used refrigerant in com mercial refrigeration: R134a. However, some technical and thermodynamic

R. Mastrullo; A. W. Mauro; A. Rosato; G. P. Vanoli

65

Infrared absorption spectrum of liquid cryogen R-134a  

NASA Astrophysics Data System (ADS)

Cryogen spray cooling (CSC) is an effective method to minimize epidermal damage during laser treatment of various cutaneous anomalies such as port wine stains, excess hair, and facial rhytides. Radiometric temperature measurements provide a noninvasive method to estimate the skin surface temperature. Since the infrared absorption spectrum of the cryogen film has remained unknown, assumptions for those values may lead to inaccurate temperature estimations. We have constructed several high-pressure infrared transparent cuvettes to determine the absorption coefficient of room temperature R-134a in liquid phase using Fourier Transform Infrared Spectroscopy (FTIR) in the 2.5 - 14 ?m spectral bandwidth. Results demonstrate that liquid R-134a has several absorption bands in the infrared, with those between 7 - 10.5 and 11.5 - 12.5 ?m being the most prominent. Additionally, the absorption coefficient at two common radiometric bands, 3 - 5 and 7 - 11 ?m differ by four orders of magnitude. Results of this study will lead to further improvements in interpreting radiometric temperature measurements when using CSC.

Pikkula, Brian M.; Guiwan, Edword; Chao, Edward; Anvari, Bahman

2004-07-01

66

Thermophysical properties of 1,1,1,2-tetrafluoroethane (R-134a)  

Microsoft Academic Search

The present hypothesis of depletion of the stratospheric ozone layer by some chlorofluorocarbons has prompted a lot of research and development of new stratospherically safe fluids in various uses such as refrigerants, blowing agents in foams, aerosol propellants, solvents, and many other uses. In the areas of certain refrigeration needs 1,1,1,2-tetrafluoroethane (R-134a) has been considered as a possible alternate to

R. S. Basu; D. P. Wilson

1989-01-01

67

FRICTION CHARACTERISTICS OF WATER, R-134a, AND AIR IN SMALL TUBES  

Microsoft Academic Search

This manuscript provides a systematic test of friction characteristic for air, water, and liquid refrigerant R-134a in 10 tubes with inside diameters from 0.173 to 4.01 mm. The test results show that the conventional minor losses correlations for large tubes may be adequately used to estimate the related inlet, exit and acceleration components for water, refrigerant, and low-speed air flow

Chien-Yuh Yang

2003-01-01

68

Thermophysical properties of 1,1,1,2-tetrafluoroethane (R-134a)  

SciTech Connect

The present hypothesis of depletion of the stratospheric ozone layer by some chlorofluorocarbons has prompted a lot of research and development of new stratospherically safe fluids in various uses such as refrigerants, blowing agents in foams, aerosol propellants, solvents, and many other uses. In the areas of certain refrigeration needs 1,1,12-tetrafluoroethane (R-134a) has been considered as a possible alternate to the use of dichloro-difluoromethane (R-12), the most commonly used refrigerant. R-12 is estimated to have a higher potential for ozone depletion. This will require a large number of thermophysical property data to help in designing equipment and also in manufacturing R-134a. This paper is intended to fill that need. The paper details the measurement and correlation of some of the important thermophysical properties such as vapor pressure, liquid density, and pressure-volume-temperature. The measured P-V-T data have been used to generate a Martin-Hou-type equation of state for this fluid over a wide range of temperature and pressure. Correlating equations are also developed for vapor pressure, liquid density, and ideal-gas specific heat. Ideal-gas specific heat has been estimated from measured spectroscopic data. The correlating equations can be used to generate the thermodynamic tables and charts. The critical temperature of R-134a has also been measured. Critical density and pressure have been estimated from measured data. The data and the correlations presented here are expected to be very useful to the refrigeration industry in the development of R-134a as a working fluid for refrigeration applications.

Basu, R.S.; Wilson, D.P. (Allied-Signal Inc, Buffalo, NY (USA))

1989-05-01

69

Two-Phase Flow Visualization of R134A in a Multiport Microchannel Tube  

Microsoft Academic Search

Results are presented from a flow visualization investigation of a multiport microchannel tube using R134a, a medium pressure refrigerant. The study covers mass fluxes from 50-300 kg\\/s.m 2 and qualities ranging from 10-90%, with a 6-port microchannel tube with a hydraulic diameter of 1.5 mm under adiabatic conditions. The results from the flow visualization studies indicate that several flow configurations

Victor G. Niño; Predrag S. Hrnjak; Ty A. Newell

2003-01-01

70

Simulation studies on R134a—DMAC based half effect absorption cold storage systems  

Microsoft Academic Search

This paper presents simulation studies conducted on a half effect vapour absorption cycle using R134a-DMAC as the refrigerant-absorbent pair with low temperature heat sources for cold storage applications. The intermediate pressure of the cycle has been optimized for maximum COP. The effects of the temperatures of the evaporator, condenser, absorber and generator on the COP of the cycle have also

S. Arivazhagan; S. N. Murugesan; R. Saravanan; S. Renganarayanan

2005-01-01

71

Computing Isentropic Flow Properties of Air/R-134a Mixtures  

NASA Technical Reports Server (NTRS)

MACHRK is a computer program that calculates isentropic flow properties of mixtures of air and refrigerant R-134a (tetrafluoroethane), which are used in transonic aerodynamic testing in a wind tunnel at Langley Research Center. Given the total temperature, total pressure, static pressure, and mole fraction of R-134a in a mixture, MACHRK calculates the Mach number and the following associated flow properties: dynamic pressure, velocity, density, static temperature, speed of sound, viscosity, ratio of specific heats, Reynolds number, and Prandtl number. Real-gas effects are taken into account by treating the gases comprising the mixture as both thermally and calorically imperfect. The Redlich-Kwong equation of state for mixtures and the constant-pressure ideal heat-capacity equation for the mixture are used in combination with the departure- function approach of thermodynamics to obtain the equations for computing the flow properties. In addition to the aforementioned calculations for air/R-134a mixtures, a research version of MACHRK can perform the corresponding calculations for mixtures of air and R-12 (dichlorodifluoromethane) and for air/SF6 mixtures. [R-12 was replaced by R-134a because of environmental concerns. SF6 has been considered for use in increasing the Reynolds-number range.

Kvaternik, Ray

2006-01-01

72

Characterization of R-134a superheated droplet detector for neutron detection.  

PubMed

R-134a (C2H2F4) is a low cost, easily available and chlorine free refrigerant, which in its superheated state can be used as an efficient neutron detector. Due to its high solubility in water the R-134a based superheated droplet detectors (SDD) are usually very unstable unless the detector is fabricated using a suitable additive, which stabilizes the detector. The SDD is known to have superheated droplets distributed in a short-lived and in a relatively long-lived metastable states. We have studied the detector response to neutrons using a (241)AmBe neutron source and obtained the temperature variation of the nucleation parameters and the interstate kinetics of these droplets using a two-state model. PMID:24675477

Mondal, Prasanna Kumar; Sarkar, Rupa; Chatterjee, Barun Kumar

2014-08-01

73

Experimental analysis of a window air conditioner with a R-22 and R32/R125/R134a mixture  

SciTech Connect

Much experimental and theoretical analysis of potential R-22 replacements has been accomplished. However, published information about the experimental analysis of any off-the-shelf air conditioner with a potential R-22 replacement at realistic, operating conditions is still rare. This type of work could be useful because it provides baseline data for comparing the performance of R-22 and its potential replacement at drop-in conditions. In this study, an off-the-shelf window air conditioner was tested at Air Conditioning and Refrigeration Institute (ARI)-rated indoor conditions and at different ambient temperatures, including the ARI-rated outdoor condition, with R-22 and with its potential replacement, a ternary mixture of R-32(30%)/R-125(10%)/R-134a(60%) (the ternary mixture). A test rig was built that provided for baseline operation and for the option of operating the system with a flooded evaporator by means of liquid over-feeding (LOF). The test results indicated the cooling capacity of the ternary mixture was 7.7% less than that of R-22 at 95{degrees}F ambient for baseline operation. The cooling capacity for both refrigerants improved when a flooded evaporator, or LOF, was used. For LOF operation, the cooling capacity of the ternary mixture was only 1.1% less than that of R-22. The ternary mixture had slightly higher compressor discharge pressure, a lower compressor discharge temperature, slightly lower compressor power consumption, and a higher compressor high/low pressure ratio.

Mei, V.C.; Chen, F.C.; Chen, D.T. [Oak Ridge National Lab., TN (United States); HuangFu, E.P. [USDOE, Washington, DC (United States)

1995-07-01

74

Condensation pressure drop of R22, R134a and R410A in a single circular microtube  

NASA Astrophysics Data System (ADS)

The condensation pressure drop characteristics for pure refrigerants R22, R134a, and a binary refrigerant mixture R410A without lubricating oil in a single circular microtube were investigated experimentally. The test section consists of 1,220 mm length with horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The experiments were conducted at refrigerant mass flux of 450-1,050 kg/m2s, and saturation temperature of 40°C. The main experimental results showed that the condensation pressure drop of R134a is higher than that of R22 and R410A for the same mass flux. The experimental data were compared against 14 two-phase pressure drop correlations. A new pressure drop model that is based on a superposition model for refrigerants condensing in the single circular tube is presented.

Son, Chang-Hyo; Oh, Hoo-Kyu

2012-08-01

75

Experimental measurements for condensation of downward-flowing R123\\/R134a in a staggered bundle of horizontal low-finned tubes with four fin geometries  

Microsoft Academic Search

Experiments were conducted to obtain row-by-row heat and mass transfer data during condensation of downward-flowing zeotropic mixture R123\\/R134a in a staggered bundle of horizontal low-finned tubes. The vapor temperature and the mass fraction of R134a at the tube bundle inlet were about 50°C and 14%, respectively. The refrigerant mass velocity ranged from 9 to 34 kg m?2 s?1, and the

H. Honda; H. Takamatsu; N. Takata

1999-01-01

76

Effect of Oils on Kinematic Viscosity of R134a  

NASA Astrophysics Data System (ADS)

The kinematic viscosity defined as a ratio of viscosity to density is one of the key properties in producing technically important dimensionless numbers such as Prandtl and Reynolds numbers. We measured both viscosity and density of R134a/POE and R134a/PAG mixtures at saturation in the range of relatively low oilconcentrations. The density measurements for oil-concentrations up to 50 mass% were conducted with a densimeter making use of glass buoys within overall uncertainty of ±1.0%, and the viscosity measurements for oil-concentrations up to 16 mass% were carried out with an oscillating-cup viscometer making use of polarizer with overall uncertainty less than ±3.5%. The kinematic viscosities obtained from the experimental viscosity and density data are presented for both R134a/POE and R134a/PAG mixtures in the range of temperatures from 278 K to 288 K for oil-concentrations up to 15 mass%. The oil-concentration dependence of the kinematic viscosity for both mixtures is also reported.

Sato, Tomoaki; Takaishi, Yoshinori; Oguchi, Kosei

77

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

78

Horizontal Nucleate Flow Boiling Heat Transfer Coefficient Measurements and Visual Observations for R12, R134a, and R134a/Ester Lubricant Mixtures.  

National Technical Information Service (NTIS)

The paper presents a calorimetric and visual investigation of horizontal nucleate flow boiling of five different fluids: (1) dichlorodifluoromethane (R12), (2) 1,1,1,2-tetrafluoroethane (R134a), (3) R134a/1.7% proprietary polyol ester lubricant, (4) R134a...

M. A. Kedzierski M. P. Kaul

1993-01-01

79

Microscopic structure of liquid 1-1-1-2-tetrafluoroethane (R134a) from Monte Carlo simulation.  

PubMed

1-1-1-2-tetrafluoroethane (R134a) is one of the most commonly used refrigerants. Its thermophysical properties are important for evaluating the performance of refrigeration cycles. These can be obtained via computer simulation, with an insight into the microscopic structure of the liquid, which is not accessible to experiment. In this paper, vapour-liquid equilibrium properties of R134a and its liquid microscopic structure are investigated using coupled-decoupled configurational-bias Monte Carlo simulation in the Gibbs ensemble, with a recent potential [J. Phys. Chem. B 2009, 113, 178]. We find that the simulations agree well with the experimental data, except at the vicinity of the critical region. Liquid R134a packs like liquid argon, with a coordination number in the first solvation shell of 12 at 260 K. The nearest neighbours prefer to be localized in three different spaces around the central molecule, in such a manner that the dipole moments are in a parallel alignment. Analysis of the pair interaction energy shows clear association of R134a molecules, but no evidence for C-HF type hydrogen bonding is found. The above findings should be of relevance to a broad range of fluoroalkanes. PMID:20830386

Do, Hainam; Wheatley, Richard J; Hirst, Jonathan D

2010-10-28

80

R134a flow patterns in small-diameter tubes  

Microsoft Academic Search

R134a vapour-liquid two-phase flow patterns were studied in vertical small diameter tubes. The observed flow patterns include bubbly, dispersed bubble, slug, churn, annular and mist flow. Six integrated flow pattern maps, derived for two internal diameters (2.01 and 4.26 mm) and three different pressures (6.0, 10.0, 14.0 bar), are presented. Some transition boundaries, such as slug-churn and churn-annular, were found

L. Chen; Y. S. Tian; T. G. Karayiannis

2005-01-01

81

Hydrogen Refrigerator Would Cool Below 10 K  

NASA Technical Reports Server (NTRS)

Closed-cycle hydrogen refrigerator uses low-level heat energy to cool objects to temperature of 10 K. Refrigerator needs only fraction of energy of previous equipment with similar low-temperature capability. Unit compact and light in weight. With valves as only moving parts, reliable for many years. Refrigeration concept adapted to cooling superconducting magnets on magnetically levitated railcars, nuclear-particle accelerators, and variety of other cryogenic equipment.

Jones, J. A.

1986-01-01

82

Two phase boiling characteristics of R-134a and R-12 in annuli of enhanced surface tubing  

SciTech Connect

In this paper an experimental study of flow boiling heat transfer characteristics of R-12 and R-134a, in the annuli of a horizontal enhanced surface tubing evaporator is presented. The experiments show two regions of heat transfer: a nucleate boiling region where the heat transfer depends mainly on heat flux and, a forced convective region where the heat transfer depends only on the refrigerant flow rate.

Sami, S.M.; Duong, T.N. (Mechanical Engineering, School of Engineering, Univ. of Moncton, Moncton, N.B., E1A 3E9 (CA)); Snelson, W.K. (National Research Council of Canada, Low Temperature Lab., Ottawa, Ontario K1A 0R6 (CA))

1992-03-01

83

Status of the round robin on the transport properties of R134a  

NASA Astrophysics Data System (ADS)

The paper contains a status report on an international project coordinated by the Subcommittee on Transport Properties of Commission 1.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a. The project has involved the remeasurement of the transport properties of a single sample of R134a in nine laboratories throughout the world in order to test the hypothesis that at least part of the discrepancy could be attributed to the purity of the sample. This paper provides an intercomparison of the new experimental results obtained to data in this project for the viscosity and the thermal conductivity in both gaseous and liquid phases. The agreement between the viscosity data from the laboratories contributing to the project was improved with several techniques, now producing consistent results. This suggests that the purity of the samples of R134a used in previous work was at least partly reponsible for the discrepancies observed. For the thermal conductivity in the liquid phase the results of the measurements are also more consistent than before, although not for all experimental techniques. Not all of the previous measurements suffered from significant sample impurities, so the present measurements on a consistent high-purity sample can he used to detect data sets which are outhers, possibly because of impurities. Identification of laboratories and techniques with systematic differences may require the examination of data for several fluids. The implications for future measurements of the transport properties of other refrigerants are significant.

Assael, M. J.; Nagasaka, Y.; Nieto de Castro, C. A.; Perkins, R. A.; Ström, K.; Vogel, E.; Wakeham, W. A.

1995-01-01

84

R134a and various mixtures of R22\\/R134a as an alternative to R22 in vapour compression heat pumps  

Microsoft Academic Search

The performance of an air to water vapor compression heat pump has been investigated experimentally. The main purpose of this study was to investigate the possibilities of using R134a as a working fluid to replace R22 for vapor compression heat pumps. Pure R22, pure R134a and some binary mixtures of R22\\/R134a were considered as working fluids. The performance of the

S. Karagoz; M. Yilmaz; O. Comakli; O. Ozyurt

2004-01-01

85

Experimental performance of ozone-safe alternative refrigerants: Experimental performance comparisons of R32, R125, R143a, R218, R134a, R152a, R134, R124, R142b, RC318 and R143 in a refrigeration circuit.  

National Technical Information Service (NTIS)

Several compounds proposed as near term or longer range substitutes for the regulated chlorofluorocarbon (CFC) refrigerants were tested in a breadboard vapor-compression circuit, and their performance was evaluated relative to more commonly used refrigera...

J. R. Sand E. A. Vineyard R. J. Nowak

1990-01-01

86

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

87

Potential Refrigerants for Power Electronics Cooling  

SciTech Connect

In the past, automotive refrigerants have conventionally been used solely for the purpose of air conditioning. However, with the development of hybrid-electric vehicles and the incorporation of power electronics (PEs) into the automobile, automotive refrigerants are taking on a new role. Unfortunately, PEs have lifetimes and functionalities that are highly dependent on temperature and as a result thermal control plays an important role in the performance of PEs. Typically, PEs are placed in the engine compartment where the internal combustion engine (ICE) already produces substantial heat. Along with the ICE heat, the additional thermal energy produced by PEs themselves forces designers to use different cooling methods to prevent overheating. Generally, heat sinks and separate cooling loops are used to maintain the temperature. Disturbingly, the thermal control system can consume one third of the total volume and may weigh more than the PEs [1]. Hence, other avenues have been sought to cool PEs, including submerging PEs in automobile refrigerants to take advantage of two-phase cooling. The objective of this report is to explore the different automotive refrigerants presently available that could be used for PE cooling. Evaluation of the refrigerants will be done by comparing environmental effects and some thermo-physical properties important to two-phase cooling, specifically measuring the dielectric strengths of potential candidates. Results of this report will be used to assess the different candidates with good potential for future use in PE cooling.

Starke, M.R.

2005-10-24

88

Effect of void fraction models on the film thickness of R134a during downward condensation in a vertical smooth tube  

Microsoft Academic Search

In the present study, the void fraction and film thickness of pure R-134a flowing downwards in a vertical condenser tube are indirectly determined using relevant measured data together with an annular flow model and various void fraction models reported in the open literature. The vertical test section is a countercurrent flow double tube heat exchanger with refrigerant flowing down in

A. S. Dalkilic; S. Laohalertdecha; S. Wongwises

2009-01-01

89

Thermal conductivity of R134a and R141b within the temperature range 240–307 K at the saturation vapor pressure  

Microsoft Academic Search

New, absolute values of the thermal conductivity of two refrigerants, R134a and R141b, in the liquid phase at saturation are reported. The measurements have been performed in transient hot-wire instruments making use of electrically insulated tantalum wires within the temperature range 240–307 K. The results are estimated to have an accuracy of ±1%.

M. Papadaki; M. Schmitt; A. Seitz; K. Stephan; B. Taxis; W. A. Wakeham

1993-01-01

90

Entanglement enhances cooling in microscopic quantum refrigerators.  

PubMed

Small self-contained quantum thermal machines function without external source of work or control but using only incoherent interactions with thermal baths. Here we investigate the role of entanglement in a small self-contained quantum refrigerator. We first show that entanglement is detrimental as far as efficiency is concerned-fridges operating at efficiencies close to the Carnot limit do not feature any entanglement. Moving away from the Carnot regime, we show that entanglement can enhance cooling and energy transport. Hence, a truly quantum refrigerator can outperform a classical one. Furthermore, the amount of entanglement alone quantifies the enhancement in cooling. PMID:24730798

Brunner, Nicolas; Huber, Marcus; Linden, Noah; Popescu, Sandu; Silva, Ralph; Skrzypczyk, Paul

2014-03-01

91

The effect of lubricant concentration, miscibility, and viscosity on R134a pool boiling  

Microsoft Academic Search

This paper presents pool boiling heat transfer data for 12 different R134a\\/lubricant mixtures and pure R134a on a Turbo-BII™-HP surface. The mixtures were designed to examine the effects of lubricant mass fraction, viscosity, and miscibility on the heat transfer performance of R134a. The magnitude of the effect of each parameter on the heat transfer was quantified with a regression analysis.

M. A Kedzierski

2001-01-01

92

Feasibility of cool storage systems in refrigeration  

NASA Astrophysics Data System (ADS)

In the present report, the economic viability and technical feasibility of selected cool storage systems are considered. Cool storage has clear potential for several applications: in connection with air-conditioning systems, domestic refrigerating and freezing systems; commercially e.g., in the dairy and vegetable industries; and in deep freezing, as in the meat industry. Air-conditioning has limited significance in Finland. For this reason it was not investigated in this study. In domestic refrigeration and freezing two systems were investigated; a controlled cooling/heating system and a simple built-in system in individual refrigerators and freezers. The central cooling/heating system in houses was found to be economically unattractive. It also has several technical drawbacks. The simple built-in system appeared to be promising. The amount of savings is rationally a function of the difference between day and night tariffs and the costs of installing an automatic switch and storage media. In the vegetable and dairy industries cool storage also has considerable potential. Several systems were investigated in this respect and compared to the conventional system. The cool storage system using Cristopia balls, one of the most common commercial systems available in Europe, was not economical at a tariff difference of 10 p/k Wh or more. Cool storage for freezing in meat plants was also investigated.

Elmahgary, Yehia; Kekkonen, Veikko; Laitinen, Ari; Pihala, Hannu

1989-05-01

93

Cooling by heating: refrigeration powered by photons.  

PubMed

We propose a new mechanism for refrigeration powered by photons. We identify the strong coupling regime for which maximum efficiency is achieved. In this case, the cooling flux is proportional to T in the low temperature limit T?0. PMID:22540566

Cleuren, B; Rutten, B; Van den Broeck, C

2012-03-23

94

Effect of Lubricant Concentration, Miscibility, and Viscosity on R134a Pool Boiling.  

National Technical Information Service (NTIS)

This paper presents pool boiling heat transfer data for twelve different R134a/lubricant mixtures and pure R134a on a Turbo-BII(trademark)-HP surface. The mixtures were designed to examine the effects of lubricant mass fraction, viscosity, and miscibility...

M. A. Kedzierski

2000-01-01

95

Thermodynamic properties of 1,1,1,2-tetrafluoroethane (R134a) in the critical region  

Microsoft Academic Search

A theoretically based simplified crossover model, which is capable of representing the thermodynamic properties of fluids in a large range of temperatures and densities around the critical point, is presented. The model is used to predict the thermodynamic properties of R134a in the critical region from a limited amount of available experimental information. Values for various thermodynamic properties of R134a

S. Tang; G. X. Jin; J. V. Sengers

1991-01-01

96

Effect of Fin Geometry on Condensation of R134a in a Staggered Bundle of Horizontal Finned Tubes  

NASA Astrophysics Data System (ADS)

Experimental results are presented that show the effect of fin geometry on condensation of refrigerant R134a in a staggered bundle of horizontal fined tubes. Two kinds of conventional low-fin tubes and three kinds of three-dimensional fin tubes were tested. The refrigerant mass velocity ranged from 8 to 23 kg/m2s and the condensation temperature difference from 1.5 to 12 K. In most cases, the highest performance was obtained by one of the three-dimensional fin tubes. In the case of high mass velocity and high film Reynolds number, however, the highest performance was obtained by one of the low-fin tubes. The results were compared with previous experimental results for bundles of smooth tubes and low-fin tubes.

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

97

Two-phase frictional pressure gradient of R236ea, R134a and R410A inside multi-port mini-channels  

Microsoft Academic Search

In the present paper the pressure drop characteristics of a 1.4mm hydraulic diameter multiport minichannel tube during adiabatic two-phase flow of HFC refrigerants are discussed. The tube consists of eleven parallel rectangular cross section channels. Although much experimental research has been devoted to investigate the pressure drop characteristics of R134a inside multiport minichannels in the last years, very little information

A. Cavallini; D. Del Col; L. Doretti; M. Matkovic; L. Rossetto; C. Zilio

2005-01-01

98

Measurements of the thermal conductivity of R22, R123, and R134a in the temperature range 250–340 K at pressures up to 30 MPa  

Microsoft Academic Search

This paper reports new, absolute measurements of the thermal conductivity of the liquid refrigerants R22, R123, and R134a in the temperature range 250–340 K at pressures from saturation up to 30 MPa. The measurements, performed in a transient hot-wire instrument employing two anodized tantalum wires as the heat source, have an estimated uncertainty of ±0.5%. A recently developed semiempirical scheme

M. J. Assael; E. Karagiannidis

1993-01-01

99

The characteristics and visualization of critical heat flux of R-134a flowing in a vertical annular geometry with spacer grids  

Microsoft Academic Search

In the present paper, critical heat flux (CHF) experiments of forced convection boiling were performed to investigate the CHF characteristics of a vertical annular channel with one heated rod and four spacer grids for new refrigerant R-134a. The experiments were conducted under outlet pressure of 11.6, 13, 16 and 20bar, mass fluxes of 100–600kg\\/m2s, and inlet temperatures of 25–40°C. The

Kwi Lim Lee; In Cheol Bang; Soon Heung Chang

2008-01-01

100

Effect of CuO nanolubricant on R134a pool boiling heat transfer  

Microsoft Academic Search

This paper quantifies the influence of CuO nanoparticles on the boiling performance of R134a\\/polyolester mixtures on a roughened, horizontal, flat surface. A lubricant based nanofluid (nanolubricant) was made with a synthetic ester and CuO particles. For the 0.5% nanolubricant mass fraction, the nanoparticles caused a heat transfer enhancement relative to the heat transfer of pure R134a\\/polyolester (99.5\\/0.5) of between 50%

Mark A. Kedzierski; M. Gong

2009-01-01

101

Thermal conductivity of R32 and its mixture with R134a  

Microsoft Academic Search

The liquid thermal conductivity of R32 (CH2F2) and R134a (CF3CH2F) was measured in the range from 223 to 323 K and from 2 to 20 MPa by the transient hot-wire method. The thermal conductivity of the R32+R134a mixture was also measured in the same range by varying the mass fraction of R32. The measured data are analyzed to obtain a

S. T. Ro; J. Y. Kim; D. S. Kim

1995-01-01

102

Floating Loop System For Cooling Integrated Motors And Inverters Using Hot Liquid Refrigerant  

DOEpatents

A floating loop vehicle component cooling and air-conditioning system having at least one compressor for compressing cool vapor refrigerant into hot vapor refrigerant; at least one condenser for condensing the hot vapor refrigerant into hot liquid refrigerant by exchanging heat with outdoor air; at least one floating loop component cooling device for evaporating the hot liquid refrigerant into hot vapor refrigerant; at least one expansion device for expanding the hot liquid refrigerant into cool liquid refrigerant; at least one air conditioning evaporator for evaporating the cool liquid refrigerant into cool vapor refrigerant by exchanging heat with indoor air; and piping for interconnecting components of the cooling and air conditioning system.

Hsu, John S [Oak Ridge, TN; Ayers, Curtis W [Kingston, TN; Coomer, Chester [Knoxville, TN; Marlino, Laura D [Oak Ridge, TN

2006-02-07

103

Stability and activity of lipase in subcritical 1,1,1,2-tetrafluoroethane (R134a).  

PubMed

The stability and activity of commercial immobilized lipase from Candida antarctica (Novozym 435) in subcritical 1,1,1,2-tetrafluoroethane (R134a) was investigated. The esterification of oleic acid with glycerol was studied as a model reaction in subcritical R134a and in solvent-free conditions. The results indicated that subcritical R134a treatment led to significant increase of activity of Novozym 435, and a maximum residual activity of 300% was measured at 4 MPa, 30 degrees C after 7 h incubation. No deactivation of Novozym 435 treated with subcritical R134a under different operation factors (pressure 2-8 MPa, temperature 30-60 degrees C, incubation time 1-12 h, water content 1:1, 1:2, 1:5 enzyme/water, depressurization rate 4 MPa/1 min, 4 MPa/30 min, 4 MPa/90 min) was observed. While the initial reaction rate was high in subcritical R134a, higher conversion was obtained in solvent-free conditions. Though the apparent conversion of the reaction is lower in subcritical R134a, it is more practicable, especially at low enzyme concentrations desired at commercial scales. PMID:17909872

Yu, Gang; Xue, Yong; Xu, Wei; Zhang, Jing; Xue, Chang Hu

2007-12-01

104

Improved Regenerative Sorbent-Compressor Refrigerator  

NASA Technical Reports Server (NTRS)

Conceptual regenerative sorbent-compressor refrigerator attains regeneration efficiency and, therefore, overall power efficiency and performance greater than conventional refrigerators. Includes two fluid loops. In one, CH2FCF3 (R134a) ciculates by physical adsorption and desorption in four activated-charcoal sorption compressors. In other, liquid or gas coolant circulated by pump. Wave of regenerative heating and cooling propagates cyclically like peristatic wave among sorption compressors and associated heat exchangers. Powered by electricity, oil, gas, solar heat, or waste heat. Used as air conditioners, refrigerators, and heat pumps in industrial, home, and automotive applications.

Jones, Jack A.

1992-01-01

105

Compounds produced by motor burnouts of refrigeration systems  

SciTech Connect

The phase-out of chlorofluorocarbons has necessitated the introduction of alternate refrigerants. R22 (CF{sub 2}ClH), R134a (CF{sub 3}CH{sub 2}F), and R507 (50/50 CHF{sub 2}CF{sub 3}/CF{sub 3}CH{sub 3}) are newer fluids which are used in cooling systems. Recently, concern over the possible formation of toxic compounds during electrical arcing through these fluids has prompted us to identify their electrical breakdown products by electron ionization GC/MS. For example, it is known that perfluoroisobutylene (PFIB), which have an threshold limit value of 10 ppb (set by the American Conference of Government Industrial Hygienists), is produced from the thermal and electrical breakdown of some refrigerants. We have used specially designed test cells, equipped with electrodes, to simulate the electrical breakdown of R22, R134a, and R507 in refrigeration systems.

Koester, C.; Hawley-Fedder, R.; Foiles, L.

1995-05-24

106

Comparison of dilution effects of R134a and nitrogen on flammable hydrofluorocarbons  

NASA Astrophysics Data System (ADS)

An experimental apparatus has been built to measure the flammability limits of combustible gases based on Chinese national standard GB/T 12474-90. The flammability limits of four binary mixtures of R161/R134a, R152a/R134a, R161/N2 and R152a/N2 were measured with this apparatus at atmospheric pressure and ambient temperature. The fuel inertization points (FIP) of these mixtures can be found from the envelopes. Comparisons were made with the literature data; good agreement for most measurements was obtained. R134a was found to have a better dilution effect than nitrogen in reducing the flammability of hydrofluorocarbons.

Li, Zhenming; Gong, Maoqiong; Wu, Jianfeng; Zhou, Yuan

2009-12-01

107

Thermal conductivity of R32 and its mixture with R134a  

SciTech Connect

The liquid thermal conductivity of R32 (CH{sub 2}F{sub 2}) and R134a (CF{sub 3}CH{sub 2}F) was measured in the range from 223 to 323 K and from 2 to 20 MPa by the transient hot-wire method. The thermal conductivity of the R32+R134a mixture was also measured in the same range by varying the mass fraction of R32. The measured data are analyzed to obtain a correlation in terms of temperature, pressure and composition of the mixture. The uncertainty of our measurements is estimated to be within {+-}2%.

Ro, S.T.; Kim, J.Y.; Kim, D.S. [Seoul National Univ. (Korea, Republic of)

1995-09-01

108

Hybrid refrigeration/sorption solar-cooling systems  

SciTech Connect

The hybrid refrigeration/sorption concept is a technically feasible approach to solar cooling which has not yet been systematically evaluated. Various system configurations are possible, each with advantages and disadvantages relative to the others, and with respect to solar cooling systems based on the individual absorption, Rankine, and desiccant technologies. Conventional cooling and dehumidification, sorption dehumidification, and the effects on the refrigeration unit of adding a dehumidifier are discussed.

Curran, H.M.

1981-08-01

109

Explosion behaviour of the ‘non-flammable’ CFC substitute 1,1,1,2-tetrafluoroethane (R134a)  

Microsoft Academic Search

The explosion ranges of R134a\\/nitrogen\\/oxygen mixtures have been investigated at atmospheric pressure. The results of these full flammability tests at 20 °C and at 280 °C are presented in a triangular diagram. In addition, the influence of pressure on the flammability of R134a\\/air mixtures has also been studied.Under normal conditions, R134a is a non-flammable gas but exhibits an explosion range

S. Dietlen; H. Hieronymus; B. Plewinsky; V. Schröder; H. Steen

1995-01-01

110

Status of the round robin on the transport properties of R134a  

Microsoft Academic Search

The paper contains a status report on an international project coordinated by the Subcommittee on Transport Properties of Commission 1.2 of the International Union of Pure and Applied Chemistry. The project has been conducted to investigate the large discrepancies between the results reported by various authors for the transport properties of R134a. The project has involved the remeasurement of the

M. J. Assael; Y. Nagasaka; C. A. Nieto de Castro; R. A. Perkins; K. Ström; E. Vogel; W. A. Wakeham

1995-01-01

111

An electronic nose for the identification of Forane R134a in an air conditioned atmosphere  

Microsoft Academic Search

An electronic nose based on a TGS type sensor array for the main detection of Forane R134a has been characterised under closely controlled gas temperature and humidity conditions. This paper presents the dependence of the TGS sensor array to the gas temperature and the relative humidity rate values. A model is proposed for the sensor array behaviour for each of

Claude Delpha; Maryam Siadat; Martine Lumbreras

2000-01-01

112

Experimental and Numerical Investigation of R-134a Flow through a Lateral Type Diabatic Capillary Tube  

Microsoft Academic Search

This paper presents the performance of R-134a through a diabatic capillary tube with lateral configuration. The paper is divided into two sections: (1) an experimental investigation of straight and helical diabatic capillary tubes and (2) a numerical investigation of the straight diabatic capillary tube. In the experimental investigation, the effects of parameters such as capillary tube diameter, capillary tube length,

Mohd. Kaleem Khan; Ravi Kumar; Pradeep K. Sahoo

2008-01-01

113

Transport properties of 1,1,1,2-tetrafluoroethane (R134a)  

Microsoft Academic Search

New equations for the thermal conductivity and the viscosity of R134a that are valid in a wide range of pressures and temperatures are presented. They were obtained through a theoretically based, critical evaluation of the available experimental data, which showed considerable inconsistencies between data sets, in particular in the vapor phase. In the critical region the observed enhancement in the

R. Krauss; J. Luettmer-Strathmann; J. V. Sengers; K. Stephan

1993-01-01

114

Keeping Cool With Solar-Powered Refrigeration  

NASA Technical Reports Server (NTRS)

In the midst of developing battery-free, solar-powered refrigeration and air conditioning systems for habitats in space, David Bergeron, the team leader for NASA's Advanced Refrigerator Technology Team at Johnson Space Center, acknowledged the need for a comparable solar refrigerator that could operate in conjunction with the simple lighting systems already in place on Earth. Bergeron, a 20-year veteran in the aerospace industry, founded the company Solus Refrigeration, Inc., in 1999 to take the patented advanced refrigeration technology he co-developed with his teammate, Johnson engineer Michael Ewert, to commercial markets. Now known as SunDanzer Refrigeration, Inc., Bergeron's company is producing battery-free, photovoltaic (PV) refrigeration systems under license to NASA, and selling them globally.

2003-01-01

115

Compounds produced by motor burnouts of refrigeration systems.  

National Technical Information Service (NTIS)

The phase-out of chlorofluorocarbons has necessitated the introduction of alternate refrigerants. R22 (CF(sub 2)ClH), R134a (CF(sub 3)CH(sub 2)F), and R507 (50/50 CHF(sub 2)CF(sub 3)/CF(sub 3)CH(sub 3)) are newer fluids which are used in cooling systems. ...

C. Koester R. Hawley-Fedder L. Foiles

1995-01-01

116

Ion signals with R134a and R134 in a parallel plate proportional counter  

NASA Astrophysics Data System (ADS)

The electrical signals from a PPAC (parallel plate avalanche counter) are identical for R134a (1,1,1,2-tetrafluoroethane) and R134 (1,1,2,2-tetrafluoroethane) except for the ion part, which, for R134a, is slower and smaller, but with the same area. The two compounds are identical except for the location of one fluorine atom. With three fluorine atoms on one end, the more common R134a has a large electric dipole moment, about the same as water; while R134 is symmetric, with no dipole moment. The attraction of the polar R134a molecules interferes with the motion of the ions, which results in a longer ion collection time. The counter is two circular plates of 1.0 cm^2 area separated by 0.5 mm operating at 700 torr and 2120 V. The ion signal is constant for a time t0 and then goes linearly to zero at time t1. The values of t0 and t1 are 1.3 ?s and 1.8 ?s for R134a, but only 0.8 ?s and 1.3 ?s for R134. These are not precise times because the signals are very small and the values depend on the location of the primary ion formation (from a ^137Cs ? source). During the constant part of the signal the ions are moving between the plates. The signal goes toward zero as the ions are collected at the cathode. For both gasses the large signal from electrons is fast with a full width at half maximum of only 1.0 ns.

Norbeck, Edwin; Olson, J. E.; Onel, Y.

2006-10-01

117

Flow-boiling of R22, R134a, R507, R404A and R410A inside a smooth horizontal tube  

Microsoft Academic Search

Flow boiling heat transfer coefficients of R22, R134a, R507, R404A and R410A inside a smooth horizontal tube (6mm I.D., 6m length) were measured at a refrigerant mass flux of about 360kg\\/m2s varying the evaporating pressure within the range 3–12bar, with heat fluxes within the range 11–21kW\\/m2. The experimental data are discussed in terms of the heat transfer coefficients as a

A. Greco; G. P. Vanoli

2005-01-01

118

Flow boiling heat transfer of R134a, R236fa and R245fa in a horizontal 1.030 mm circular channel  

Microsoft Academic Search

This research focuses on acquiring accurate flow boiling heat transfer data and flow pattern visualization for three refrigerants, R134a, R236fa and R245fa in a 1.030mm channel. We investigate trends in the data, and their possible mechanisms, for mass fluxes from 200 to 1600kg\\/m2s, heat fluxes from 2.3kW\\/m2 to 250kW\\/m2 at Tsat=31°C and ?Tsub from 2 to 9K. The local saturated

Chin L. Ong; John R. Thome

2009-01-01

119

4. INTERIOR VIEW OF CLUB HOUSE REFRIGERATION UNIT, SHOWING COOLING ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. INTERIOR VIEW OF CLUB HOUSE REFRIGERATION UNIT, SHOWING COOLING COILS AND CORK-LINED ROOM. CAMERA IS BETWEEN SEVEN AND EIGHT FEET ABOVE FLOOR LEVEL, FACING SOUTHEAST. - Swan Falls Village, Clubhouse 011, Snake River, Kuna, Ada County, ID

120

An experimental study of the flow of R-134a inside an adiabatic spirally coiled capillary tube  

Microsoft Academic Search

This paper presents an experimental investigation for the flow of R-134a inside an adiabatic spirally coiled capillary tube. The effect of various geometric parameters like capillary tube diameter, length and coil pitch for different capillary tube inlet subcoolings on the mass flow rate of R-134a through the spiral capillary tube geometry has been investigated. It has been established that the

Mohd. Kaleem Khan; Ravi Kumar; Pradeep K. Sahoo

2008-01-01

121

Hybrid vapor compression refrigeration system with an integrated ejector cooling cycle  

Microsoft Academic Search

A refrigeration system was developed which combines a basic vapor compression refrigeration cycle with an ejector cooling cycle. The ejector cooling cycle is driven by the waste heat from the condenser in the vapor compression refrigeration cycle. The additional cooling capacity from the ejector cycle is directly input into the evaporator of the vapor compression refrigeration cycle. The governing equations

Yinhai Zhu; Peixue Jiang

122

Nucleate boiling heat transfer of R134a on enhanced tubes  

Microsoft Academic Search

The present paper reports the results of an experimental investigation on saturated pool boiling heat transfer of R134a on High-Flux, Gewa-B, Turbo-CSL and Turbo-BII HP tubes. Experiments have been carried out at saturation temperatures of 5, 10 and 20°C and heat fluxes from 20 to 70kW\\/m2. At most of the experimental conditions tested, an almost negligible effect of the saturation

Gherhardt Ribatski; John R. Thome

2006-01-01

123

Performance of stationary and vibrated thermosyphon working with water and R134a  

Microsoft Academic Search

An experimental apparatus of a two-phase closed thermosyphon has been designed and constructed to predict its performance characteristics under stationary and vibrated conditions. Water and R134a are used as working fluids. Experiments are carried out over wide ranges of liquid fill ratio (0.4, 0.5, 0.6 and 0.8), length of adiabatic section (275, 325 and 350 mm), vibration frequency (0.0–4.33 Hz)

H. Z Abou-Ziyan; A Helali; M Fatouh; M. M. Abo El-Nasr

2001-01-01

124

Effects of parameters on yield for sub-critical R134a extraction of palm oil  

Microsoft Academic Search

Extraction of palm oil from its palm mesocarp using sub-critical 1,1,1,2-tetrafluoroethane (R134a) as an alternative solvent to supercritical CO2 was studied. The effects of pressure, temperature, flowrate and sample pre-treatment method on extraction yield were examined. Dynamic method was used to determine palm oil solubility at flowrate between 0.5 and 5.0ml\\/min. Extraction was performed at pressures between 45 and 100bar

A. N. Mustapa; Z. A. Manan; C. Y. Mohd Azizi; N. A. Nik Norulaini; A. K. Mohd Omar

2009-01-01

125

Evaporation of R134a in a horizontal herringbone microfin tube: heat transfer and pressure drop  

Microsoft Academic Search

An experimental investigation of in-tube evaporation of R134a has been carried out for a 4m long herringbone microfin tube with an outer diameter of 9.53mm. Measured local heat transfer coefficients and pressure losses are reported for evaporation temperatures between ?0.7 and 10.1°C and mass flow rates between 162 and 366kgm?2s?1. Results from this work are compared to experimental results from

S. Wellsandt; L. Vamling

2005-01-01

126

Flow boiling of R134a and ammonia in a plate heat exchanger  

Microsoft Academic Search

This paper presents experimental results on evaporation heat transfer for flow boiling of ammonia and of R134a in a chevron-pattern corrugated plate heat exchanger (PHE). The measurements enable the evaluation of a quasi-local heat transfer coefficient along the plate, which in turn allows discussing the two-phase distribution and the heat transfer mechanism during evaporation in a plate channel. The saturation

E. Djordjevic; S. Kabelac

2008-01-01

127

Friction factor and heat transfer coefficient of R134a liquid flow in mini-channels  

Microsoft Academic Search

This article presents an experimental study of friction factor and heat transfer coefficient for a vertical liquid up-flow of R134a. A flat aluminium multiport extruded tube composed of 11 parallel rectangular channels (3.28mm×1.47 mm) with hydraulic diameter of 2.01 mm was used. Mass flux ranges from 28 to 800 kgm?2s?1 and heat flux from 0.84 to 22 kWm?2. Working pressure

Bruno Agostini; Barbara Watel; André Bontemps; Bernard Thonon

2002-01-01

128

Experimental investigation on diabatic flow of R-134a through spiral capillary tube  

Microsoft Academic Search

The present experimental investigation has been carried out to investigate the effects of various geometric parameters on the mass flow rate of R-134a through diabatic spiral capillary tube. In diabatic flow, the capillary tube is bonded with the compressor suction-line to form a counter-flow exchanger. The lateral type of diabatic capillary tube has been investigated in the present experimental study.

Mohd. Kaleem Khan; Ravi Kumar; Pradeep K. Sahoo

2009-01-01

129

Viscosity measurements of ammonia, R32, and R134a. Vapor buoyancy and radial acceleration in capillary viscometers  

SciTech Connect

The saturated liquid viscosity of ammonia (NH{sub 3}) and of the hydrofluorocarbons, difluoromethane (CH{sub 2}F{sub 2}, R32) and 1,1,1,2-tetrafluoroethane (CF{sub 3}-CH{sub 2}F, R134a), was measured in a sealed gravitational viscometer with a straight vertical capillary. The combined temperature range was from 250 to 350 K. The estimated uncertainty of the ammonia measurements if {+-}3.3 and {+-}2 to 24% for the hydrofluorocarbons with a coverage factor of two. The results are compared with literature data which have been measured with capillary viscometers of different design. Agreement within the combined experimental uncertainty is achieved when some of the literature data sets are corrected for the vapor buoyancy effect and when a revised radial acceleration correction is applies to data which were obtained in viscometers with coiled capillaries. An improved correction for the radial acceleration is proposed. It is necessary to extend international viscometry standards to sealed gravitational capillary instruments because the apparent inconsistencies between refrigerant viscosity data from different laboratories cannot be explained by contaminated samples.

Laesecke, A.; Lueddecke, T.O.D.; Hafer, R.F.; Morris, D.J. [National Inst. of Standards and Technology, Boulder, CO (United States). Physical and Chemical Properties Div.] [National Inst. of Standards and Technology, Boulder, CO (United States). Physical and Chemical Properties Div.

1999-03-01

130

Investigation of potential benefits of compressor cooling  

Microsoft Academic Search

The compressor is certainly the largest power consumer in a vapor compression system. To reduce the power consumption of the compressors two performance improving options are investigated theoretically for refrigerants R22, R134a, R410A and R744 as working fluids. The first option is cooling the motor by external means other than using the suction gas. Analysis results for this option show

Xudong Wang; Yunho Hwang; Reinhard Radermacher

2008-01-01

131

Flow boiling heat transfer characteristics of R123 and R134a in a micro-channel  

Microsoft Academic Search

Flow boiling heat transfer in a single circular micro-channel of 0.19mm ID has been experimentally investigated with R123 and R134a for various experimental conditions: heat fluxes (10, 15, 20kW\\/m2), mass velocities (314, 392, 470kg\\/m2s), vapor qualities (0.2–0.85) and different saturation pressures (158, 208kPa for R123; 900, 1100kPa for R134a). The heat transfer trends between R123 and R134a are clearly distinguished.

Sangkwon Jeong

2009-01-01

132

Transport properties 1,1,1,2-tetrafluorethane (R134a)  

SciTech Connect

New equations for the thermal conductivity and the viscosity of R134a that are valid in a wide range of pressures and temperatures are presented. They were obtained through a theoretically based, critical evaluation of the available experimental data, which showed considerable inconsistencies between data sets, in particular in the vapor phase. In the critical region the observed enhancement in the thermal conductivity is well represented by a crossover model for the transport properties of fluids. Since thermodynamic properties enter into the calculation of the critical enhancement of the transport properties, a new fundamental equation for the critical region was developed also. 57 refs., 23 figs., 7 tabs.

Krauss, R.; Stephan, K. (Universitaet Stuttgart (Germany)); Luettmer-Strathmann, J. (Univ. of Maryland, College Park, MD (United States)); Sengers, J.V. (Univ. of Maryland, College Park, MD (United States) National Inst. of Standards and Technology, Gaithersburg, MD (United States))

1993-07-01

133

Experimental study of nucleate pool boiling of R134a on a stainless steel tube  

Microsoft Academic Search

Nucleate pool boiling of R134a is studied experimentally in the reduced pressure range 0.03?p\\/pc?0.5 (1.2bar?p?20.3 bar) for heat fluxes from q=100000 W\\/m2 down to single phase natural convection. Additionally to the heat transfer measurements, nucleation site density, up to (N\\/A)max?6000 sites\\/cm2 is measured by an optical method. The test specimen is a horizontal stainless steel tube (sandblasted) with an outer

Gerrit Barthau; Erich Hahne

2004-01-01

134

Viscosity of R134a, R32, and R125 at saturation  

SciTech Connect

This paper reports the results of the measurement of the viscosity of R134a close to the saturation time in the vapor phase. The new measurements were carried out in a vibrating-wire viscometer specially constructed for the purpose, and the results have an accuracy of {+-}2%. In addition, the opportunity is taken to present a reevaluation of earlier measurements along the saturation line of the viscosity of R32 and R125. Improved equations of state for these fluids are now available and can be employed to generate improved values for the viscosity.

Oliveira, C.M.B.P. [Univ. Aberta, Lisboa (Portugal)] [Univ. Aberta, Lisboa (Portugal); [Instituto Superior Tecnico, Lisboa (Portugal). Centro de Quimica Estrutural; Wakeham, W.A. [Imperial Coll., London (United Kingdom). Dept. of Chemical Engineering and Chemical Technology] [Imperial Coll., London (United Kingdom). Dept. of Chemical Engineering and Chemical Technology

1999-03-01

135

Effects of EHD on heat transfer enhancement and pressure drop during two-phase condensation of pure R-134a at high mass flux in a horizontal micro-fin tube  

SciTech Connect

Effects of electrohydrodynamic (EHD) on the two-phase heat transfer enhancement and pressure drop of pure R-134a condensing inside a horizontal micro-fin tube are experimentally investigated. The test section is a 2.5m long counter flow tube-in-tube heat exchanger with refrigerant flowing in the inner tube and cooling water flowing in the annulus. The inner tube is made from micro-fin horizontal copper tubing of 9.52mm outer diameter. The electrode is made from cylindrical stainless steel of 1.47mm diameter. Positive high voltage is supplied to the electrode wire, with the micro-fin tube grounded. In the presence of the electrode, a maximum heat transfer enhancement of 1.15 is obtained at a heat flux of 10kW/m{sup 2}, mass flux of 200kg/m{sup 2}s and saturation temperature of 40{sup o}C, while the application of an EHD voltage of 2.5kV only slightly increases the pressure drop. New correlations of the experimental data based on the data gathered during this work for predicting the condensation heat transfer coefficients are proposed for practical application. (author)

Laohalertdecha, Suriyan [The Joint Graduate School of Energy and Environment (JGSEE), King Mongkut's University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand); 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 10140 (Thailand)

2006-07-15

136

Optimal design of gas adsorption refrigerators for cryogenic cooling  

NASA Technical Reports Server (NTRS)

The design of gas adsorption refrigerators used for cryogenic cooling in the temperature range of 4K to 120K was examined. The functional relationships among the power requirement for the refrigerator, the system mass, the cycle time and the operating conditions were derived. It was found that the precool temperature, the temperature dependent heat capacities and thermal conductivities, and pressure and temperature variations in the compressors have important impacts on the cooling performance. Optimal designs based on a minimum power criterion were performed for four different gas adsorption refrigerators and a multistage system. It is concluded that the estimates of the power required and the system mass are within manageable limits in various spacecraft environments.

Chan, C. K.

1983-01-01

137

Prediction of heat transfer coefficient during condensation of water and R-134a on single horizontal integral-fin tubes  

Microsoft Academic Search

This paper presents a few salient features of an investigation carried out to study the heat transfer augmentation during condensation of water and R-134a vapor on horizontal integral-fin tubes. The experimental investigation was performed on two different experimental set-ups for water and R-134a. The test-sections were manufactured by machining fins over plain copper tubes of 24.4 ± 0.6 mm outside

Ravi Kumar; H. K. Varma; Bikash Mohanty; K. N. Agrawal

2002-01-01

138

Cooling SABER with a miniature pulse tube refrigerator  

NASA Astrophysics Data System (ADS)

Utah State University/Space Dynamics Laboratory, teaming with NASA Langley Research Center, is currently building the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument. Stringent mass and power constraints, together with a greater than two year mission life, led to the selection of a TRW miniature pulse tube refrigerator to cool SABER's infrared detectors to the required temperature of 75 K. This paper provides an overview of the SABER thermal management plan and the challenges encountered in matching the refrigerator characteristics with instrument performance requirements under the broadly variant space environments expected for this mission. Innovative technologies were developed to keep heat loads within the limited cooling capacity of the miniature refrigerator, as well as mechanically isolating but thermally connecting the refrigerator cold block to the focal plane assembly (FPA). A passive radiator will maintain the SABER telescope at an average temperature of 230 K while a separate radiator will reject heat from the refrigerator and electronics at approximately 260 K. Significant breadboard tests of various components of the SABER instrument have taken place and the details of one of these will be discussed. The test included attaching a miniature mechanical refrigerator, borrowed from the Air Force, to the SABER FPA. This opportunity gave the SABER team a significant head start in learning about integrating and testing issues related with the TRW miniature pulse tube refrigerator. SABER is scheduled to be launched in January 2000 as the primary instrument of NASA's TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) spacecraft. The TIMED program is being managed by the Applied Physics Laboratory at Johns Hopkins University.

Jensen, Scott M.; Batty, J. Clair; Roettker, William A.; Felt, Matthew J.

1998-09-01

139

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

140

Experimental evaluation of the internal heat exchanger influence on a vapour compression plant energy efficiency working with R22, R134a and R407C  

Microsoft Academic Search

Internal or liquid-suction heat exchangers are used in many refrigeration and air conditioning systems based on the vapour compression cycle, with the basic objective of assuring the entrance of refrigerant in liquid phase to the expansion device. This purpose is achieved by exchanging energy between the cool gaseous refrigerant leaving the evaporator and warm liquid refrigerant exiting the condenser. These

J. Navarro-Esbrí; R. Cabello; E. Torrella

2005-01-01

141

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

142

Computer model for air-cooled refrigerant condensers with specified refrigerant circuiting  

SciTech Connect

A computer model for an air-cooled refrigerant condensor is presented; the model is intended for use in detailed design analyses or in simulation of the performance of existing heat exchangers that have complex refrigerant circuiting or unusual air-side geometries. The model relies on a tube-by-tube computational approach calculating the thermal and fluid-flow performance of each tube in the heat exchanger individually, using local temperatures and heat transfer coefficients. The refrigerant circuiting must be specified; the joining or branching of parallel circuits is accommodated using appropriate mixing expressions. Air-side heat exchange correlations may be specified so that various surface geometries can be investigated. Results of the analyses of two condensers are compared to experiment.

Ellison, R.D.; Creswick, F.A.; Fischer, S.K.; Jackson, W.L.

1981-01-01

143

A passive, vapor compression refrigerator for solar cooling  

SciTech Connect

A completely passive vapor compression refrigerator is described in this paper. This refrigerator combines elements of the heat pipe and the vapor jet refrigerator and is referred to here as a heat pipe refrigerator. It may be driven with heat from low temperature solar collectors or with industrial waste heat and used to provide cooling. Compression work is provided by gas dynamic processes and liquid pumping may be obtained using gravitational or capillary forces. No power is required for operation. The device has no moving parts and may be externally similar to a heat pipe with three heat transfer zones. The working fluid is chosen to match the desired operating temperature range. Water, at subatmospheric pressure, is an appropriate fluid for operation around room temperature. Theoretical considerations indicate that the thermal coefficient of performance of the heat pipe refrigerator will depend strongly on the magnitude of the temperature difference over which it is designed to operate. results from a laboratory test confirm the concept.

Loehrke, R.I. (Colorado State Univ., Fort Collins, CO (USA). Dept. of Mechanical Engineering)

1990-08-01

144

Method for estimating the refrigeration costs of supercritical helium cooled cable superconductors  

Microsoft Academic Search

Refrigeration costs constitute an important aspect of the economics of force-cooled cable superconductors. The refrigerator power required to operate a forced cooled superconducting magnet is analyzed. The paper develops a simple method for estimating the total refrigerator power associated with a given length of cabled conductor of specified geometry. The estimate relies on the thermodynamics of supercritical helium in the

Adrian Bejan; M. Hoenig

1977-01-01

145

Transient phenomena in a low cooling thermoacoustic refrigerator  

NASA Astrophysics Data System (ADS)

A one-dimensional theoretical model is developed to describe the transient state phenomena in a low cooling standing wave Thermoacoustic Refrigerator. The model is based on the Linear Theory of Thermoacoustics. It uses Implicit Finite Difference method to calculate the temporal evolution of temperature and steady state temperature distribution in the refrigerator stack and the resonator. The cold temperatures predicted by the model are compared with those obtained by techniques given in literature, and show a very good match. Due to simplistic assumptions in the model and its one-dimensional nature, the cooldown rates are shown to be very fast compared to other experimental findings in literature. It is also seen that the resonator takes a long time to cool down compared to the stack.

Dhuley, R. C.; Atrey, M. D.

2014-01-01

146

Measurements of the Viscosity for Mixtures of R134a and Polyolester Oil at Low Oil-concentrations  

NASA Astrophysics Data System (ADS)

The paper presents new measurements on the viscosity for the mixtures of R134a and polyolester oil at low oil-concentrations. The measurements were conducted with a newly developed oscillating cup viscometer making use of polarizer at oil-concentrations between 0 and 16 mass% and temperatures from 278.15 K to 288.15 K. The uncertainty in viscosity was estimated to be less than ±4.3%. It was found that even a small amount of the oil into R134a had a significant effect on the viscosity. It increased exponentially with oil-concentration. Mixing the oil into R134a up to an oil-concentration of 16 mass% tripled the viscosity. A correlation equation as a function of temperature and oil mass fraction was formulated to interpolate the experimental viscosity data.

Sato, Tomoaki; Odaira, Akihiro; Takaishi, Yoshinori; Oguchi, Kosei

147

Development of atmospheric characteristics of chlorine-free alternative fluorocarbons. Report on R-134a and E-143a  

SciTech Connect

Rate constants have been measured for the gas phase reaction of OH radicals with 1,1,1,2-tetrafluoroethane R-134a (CH{sub 2}F-CF{sub 3}) and methyl trifluoromethyl ether E-143a (CH{sub 3}-O-CF{sub 3}) over the temperature range 298--460 K. Arrhenius expressions were derived for atmospheric modeling. The infrared absorption cross-sections for R-134a and E-143a have been measured in the region from 400 to 1600 cm{sup {minus}1} and the integrated band strengths have been calculated. The atmospheric lifetimes R-134a and E-143a have been estimated to be 11.6 years and 4.1 years respectively. Global warming potentials have been estimated over time horizons of 20, 50, 100, 200, and 500 years.

Orkin, V.L.; Khamaganov, V.G.; Guschin, A.G.; Kasimovskaya, E.E.; Larin, I.K. [Institut Energeticheskiskh Problem Khimicheskoi Fiziki, Moscow (Russian Federation)

1993-04-01

148

Heat and mass transfer characteristics of absorption of R134a into DMAC in a horizontal tube absorber  

NASA Astrophysics Data System (ADS)

In this paper the heat and mass transfer characteristics of a horizontal tube absorber for the mixture R134a/DMAC in terms of experimentally gained heat and mass transfer coefficients are presented. The heat transfer coefficient is mainly dependent on the solution’s mass flow rate. The mass transfer coefficient is strongly related to the subcooling of the solution. The data are compared to experimental absorption characteristics of water into aqueous lithium bromide in an absorption chiller. The mass transfer coefficients are of similar size whereas the heat transfer coefficients are about one order of magnitude smaller for R134a-DMAC.

Harikrishnan, L.; Maiya, M. P.; Tiwari, S.; Wohlfeil, A.; Ziegler, F.

2009-10-01

149

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

150

The vapor pressure of 1, 1, 1, 2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)  

SciTech Connect

The authors measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7 kPa (corresponding to temperatures in the range 265.6 to 313.2 K), additional measurements were made with a Burnett apparatus. The results have been combined for 1, 1, 1, 2-tetrafluoroethane with those already published from this laboratory at higher pressures to obtain a smoothing equation for the vapor pressure from 215 K to the critical temperature. For chlorodifluoromethane the results have been combined with certain published results to provide an equation for the vapor pressure at temperatures from 217 K to the critical temperature. 58 refs., 6 figs., 2 tabs.

Goodwin, A.R.H.; Defibaugh, D.R.; Weber, L.A. (National Institute of Standards and Technology, Gaithersburg, MD (United States))

1992-09-01

151

Heating surface material’s effect on subcooled flow boiling heat transfer of R134a  

SciTech Connect

In this study, subcooled flow boiling of R134a on copper (Cu) and stainless steel (SS) heating surfaces was experimentally investigated from both macroscopic and microscopic points of view. By utilizing a high-speed digital camera, bubble growth rate, bubble departure size, and nucleation site density, were able to be observed and analyzed from the microscopic point of view. Macroscopic characteristics of the subcooled flow boiling, such as heat transfer coefficient, were able to be measured as well. Experimental results showed that there are no obvious difference between the copper and the stainless surface with respect to bubble dynamics, such as contact angle, growth rate and departure size. On the contrary, the results clearly showed a trend that the copper surface had a better performance than the stainless steel surface in terms of heat transfer coefficient. It was also observed that wall heat fluxes on both surfaces were found highly correlated with nucleation site density, as bubble hydrodynamics are similar on these two surfaces. The difference between these two surfaces was concluded as results of different surface thermal conductivities.

Ling Zou; Barclay G. Jones

2012-11-01

152

Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications: Part II—heat transfer characteristics  

Microsoft Academic Search

This paper is the second of a two-part study concerning two-phase flow and heat transfer characteristics of R134a in a micro-channel heat sink incorporated as an evaporator in a refrigeration cycle. Boiling heat transfer coefficients were measured by controlling heat flux (q?=15.9?93.8W\\/cm2) and vapor quality (xe=0.26?0.87) over a broad range of mass velocity. While prior studies point to either nucleate

Jaeseon Lee; Issam Mudawar

2005-01-01

153

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

154

Two phase pressure losses of R134a in microchannel tube headers with large free flow area ratios  

Microsoft Academic Search

This paper presents the results of an experimental investigation of two-phase pressure loss of R134a in microchannel headers. Novel experimental techniques and test sections were developed to enable the accurate determination of the minor losses without obfuscating the problem with a lengthwise pressure gradient. This technique represents a departure from approaches used by other investigators that have extrapolated minor losses

John Wesley Coleman; Paul E. Krause

2004-01-01

155

Effect of CuO Nanparticle Concentration on R134a/Lubricant Pool Boiling Heat Transfer with Extensive Analysis.  

National Technical Information Service (NTIS)

This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a/polyolester mixtures on a roughened, horizontal flat surface. Nanofluids are liquids that contain dispersed nano-size particles. ...

M. A. Kedzierski

2007-01-01

156

Electron swarm coefficients in 1,1,1,2 tetrafluoroethane (R134a) and its mixtures with Ar  

NASA Astrophysics Data System (ADS)

Using a pulsed Townsend technique, we have measured the drift velocity, the longitudinal diffusion coefficient and the effective ionisation coefficient of electrons in R134a and R134a-Ar over a wide range of the density-reduced electric field intensity, E/N. Regarding the measurement of the electron drift velocities and of the effective ionization coefficients, we have covered a wider range than that hitherto achieved for pure R134a. Both the electron drift velocity and the effective ionisation coefficient have been found in very good agreement with those published in the literature, covering a shorter range of E/N. On the other hand, the swarm coefficients on R134a-Ar are, to the best of our knowledge, the first to be published. It is hoped that these data will be of interest for the test/derivation of electron collision cross sections for this important hydrofluorocarbon gas, which is nowadays of great use in gaseous detectors.

de Urquijo, J.; Juárez, A. M.; Basurto, E.; Hernández-Ávila, J. L.

2009-02-01

157

3He\\/ 4He dilution refrigerator with high cooling capacity and direct pulse tube pre-cooling  

Microsoft Academic Search

In the article, a 3He\\/4He dilution refrigerator (DR) is described which is pre-cooled by a commercial two-stage pulse tube refrigerator (PTR); cryo-liquids are not necessary with this type of milli-kelvin refrigerator. The simple design of the condensation stage of this so-called dry DR is novel and explained in detail. In most dry DRs the circulating 3He gas is cooled by

Kurt Uhlig

2008-01-01

158

Convective Boiling and Condensation Heat Transfer with a Twisted-Tape Insert for R12, R22, R152a, R134a, R290, R32/R134a, R32/R152a, R290/R134a, R134a/R600a.  

National Technical Information Service (NTIS)

This paper presents measured local-averaged heat-transfer coefficients for in-tube convective boiling and condensation of several possible alternative refrigerants with a twisted-tape insert. The heat transfer performance of five single component and two ...

M. A. Kedzierski M. S. Kim

1997-01-01

159

ASHRAE`s new application guide for absorption cooling/refrigeration using recovered heat  

SciTech Connect

This article is a brief overview of the Guide for Absorption Cooling/Refrigeration Using Recovered Heat. The overview examines the applications of the guide, it`s format and topics on a chapter basis. The authors report that ASHRAE`s purpose for developing this manual is to encourage more engineers and owners to consider using recovered heat for cooling and refrigeration.

Dorgan, C.B.; Dorgan, C.E.; Leight, S.P. [Dorgan Associates Inc., Madison, WI (United States)

1995-07-01

160

A closed cycle cascade Joule Thomson refrigerator for cooling Josephson junction magnetometers  

NASA Astrophysics Data System (ADS)

A closed cycle cascade Joule Thomson refrigerator designed to cool Josephson Junction magnetometers to liquid helium temperature is being developed. The refrigerator incorporates 4 stages of cooling using the working fluids CF4 and He. The high pressure gases are provided by a small compressor designed for this purpose. The upper stages have been operated and performance will be described.

Tward, E.; Sarwinski, R.

1985-05-01

161

Experimental study of R134A condensation heat transfer inside the horizontal micro-fin tubes  

NASA Astrophysics Data System (ADS)

The Investigation of the two-phase flow patterns and their transitions during the condensation has gained increasing interest and importance from the well-known phenomenon that the heat transfer characteristics are strongly dependent on the flow patterns. Therefore, it is very important to study on which heat transfer enhancement approach is suitable for an individual flow pattern inside a condenser, so that an accurate heat transfer mechanism can be understood that is consistent with the flow patterns. The condensation heat transfer for R134a in the two kinds of in-tube three-dimensional (3-D) micro-fin tubes with different geometries is experimentally investigated. Based on the flow pattern observations, the flow patterns in the Soliman flow regime map are divided into two-flow regimes; one with the vapor-shear-dominant annular regime and the other with the gravitational-force-dominant stratified-wavy regime. The flow regime transition criterion between the annular regime and the stratified-wavy regime is at Fr equal to 2. In the annular regime, the heat transfer coefficients h of the two kinds of in-tube 3-D micro-fin tubes decreases as the vapor quality x decreases. The regressed condensation heat transfer correlation from the experimental data of the annular flow region is obtained. The dispersibility of the experimental data is inside the limits of ±25%. In the stratified-wavy regime, the average heat transfer coefficient h of the two kinds of in-tube 3-D micro-fin tubes increases as the mass flux increases and the number of micro fins in the 3-D micro-fin tube is not the controlling factor for the performance of a condensation heat transfer. The regressed condensation heat transfer correlation of the stratified-wavy flow regime is experimentally obtained. The dispersibility of the experimental data is inside the limits of ±22%. Combined with the criteria of flow pattern transitions, the correlations can be used for the design of a condenser with 3-D micro-fin tubes.

Chen, Q.; Amano, R. S.; Xin, M. D.

2005-07-01

162

Two-phase flow in high-heat-flux micro-channel heat sink for refrigeration cooling applications: Part I––pressure drop characteristics  

Microsoft Academic Search

Two-phase pressure drop was measured across a micro-channel heat sink that served as an evaporator in a refrigeration cycle. The micro-channels were formed by machining 231?m wide×713?m deep grooves into the surface of a copper block. Experiments were performed with refrigerant R134a that spanned the following conditions: inlet pressure of Pin=1.44–6.60bar, mass velocity of G=127–654kg\\/m2s, inlet quality of xe,in=0.001–0.25, outlet

Jaeseon Lee; Issam Mudawar

2005-01-01

163

Experimental investigation on condensation heat transfer and pressure drop of R134a in a plate heat exchanger  

NASA Astrophysics Data System (ADS)

Condensation heat transfer of R134a in a vertical plate heat exchanger was investigated experimentally. The local heat transfer coefficients are determined by means of the measured local wall temperatures. A differential energy balance model is developed for data evaluation. It is found that the correlation proposed by Shah using ? and Z factors is suitable for condensation in plate heat exchangers and is adopted to fit the measured data.

Shi, Z.-Y.; Chen, J.-P.; Grabenstein, V.; Kabelac, S.

2010-11-01

164

Two-Phase Frictional Pressure Drop Multipliers for SUVA R-134a Flowing in a Rectangular Duct.  

National Technical Information Service (NTIS)

The adiabatic two-phase frictional multipliers for SUVA, R-134a flowing in a rectangular duct (with D(sub H) = 4.8 mm) have been measured for 3 nominal system pressures (0.9 MPa, T(sub sat)=35.5 deg C; 1.38 MPa, T(sub sat)=51.8 deg C; and 2.41 MPa, T(sub ...

P. Vassallo K. Keller

2005-01-01

165

Solar-assisted R22 and R134a heat pump systems for low-temperature applications  

Microsoft Academic Search

The results of the simulations for a conventional heat pump, a conventional solar air heater and two serial solar-assisted heat pump (SAHP) systems are presented in this paper. The thermodynamic properties of R22, R404a and R134a are given in the form of correlations with correlation factors higher than 0.99. The performance characteristics of the heat pump are investigated using these

H. Z. Abou-Ziyan; M. F. Ahmed; M. N. Metwally; H. M. Abd El-Hameed

1997-01-01

166

Effect of CuO Nanoparticle Concentration on R134a\\/Lubricant Pool-Boiling Heat Transfer  

Microsoft Academic Search

This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a\\/polyolester mixtures on a roughened, horizontal flat surface. Nanofluids are liquids that contain dispersed nano- size particles. Two lubricant based nanofluids (nanolubricants) were made with a synthetic polyolester and 30 nm diameter CuO particles to a 4 % and a 2 % volume

Mark A. Kedzierski

2009-01-01

167

Flow boiling in a 1.1 mm tube with R134a: Experimental results and comparison with model  

Microsoft Academic Search

A detailed comparison of flow boiling heat transfer results in a stainless steel tube of 1.1 mm internal diameter with results of a three-zone flow model are presented in this paper. The working fluid is R134a. Other parameters were varied in the range: mass flux 100–600 kg\\/m2?s; heat flux 16–150 kW\\/m2 and pressure 6–12 bar.The experimental results demonstrate that the

D. Shiferaw; T. G. Karayiannis; D. B. R. Kenning

2009-01-01

168

Examination of heat transfer correlations and a model for flow boiling of R134a in small diameter tubes  

Microsoft Academic Search

Analysis of various existing correlations including a three-zone evaporation model is made using a comparison with recent experimental results obtained in this study. Flow boiling heat transfer experiments were conducted with two stainless steel tubes of internal diameter 4.26mm and 2.01mm. The working fluid was R134a and parameters were varied in the range: mass flux 100–500kg\\/m2s; pressure 8–12bar; quality up

D. Shiferaw; X. Huo; T. G. Karayiannis; D. B. R. Kenning

2007-01-01

169

A viscosity equation of state for R134a through a multi-layer feedforward neural network technique  

Microsoft Academic Search

A multi-layer feedforward neural network (MLFN) technique is adopted for developing a viscosity equation ?=?(?,T) for R134a. The results obtained are very promising, with an average absolute deviation (AAD) of 0.63% for the currently available 571 primary data points, and are a significant improvement over those of a corresponding conventional equation in the literature. The method requires a high accuracy

G Cristofoli; L Piazza; G Scalabrin

2002-01-01

170

Augmentation of heat transfer during filmwise condensation of steam and R-134a over single horizontal finned tubes  

Microsoft Academic Search

An experimental investigation has been carried out to augment the heat transfer rate by enhancing the heat transfer coefficient during the condensation of pure vapours of steam and R-134a over horizontal finned tubes. The study was conducted for plain tubes, circular integral-fin tubes (CIFTs), spine integral-fin tubes (SIFTs) and parially spined circular integral-fin tubes (PCIFTs). The SIFT out performed the

Ravi Kumar; H. K Varma; Bikash Mohanty; K. N Agrawal

2002-01-01

171

Sound velocity and ideal-gas specific heat of gaseous 1,1,1,2-tetrafluoroethane (R134a)  

Microsoft Academic Search

A cylindrical, variable-path acoustic interferometer operating at 156.252kHz is developed for determining ideal-gas specific heats. Results of validation measurements with argon are very satisfactory, with the maximum deviation of the speed of sound equal to 3×10-4. The sound velocity of gaseous R134a has been measured at low temperatures and low pressures. The specific heat was then calculated from the results.

M. S. Zhu; L. Z. Han; K. Z. Zhang; T. Y. Zhou

1993-01-01

172

The 1- to 4-K refrigeration techniques for cooling masers on a beam waveguide antenna  

NASA Astrophysics Data System (ADS)

The status of technology is reported for various 1- to 4-K commercially available refrigeration systems capable of producing 1.5-K refrigeration to cool masers and superconducting cavity oscillators on the proposed beam waveguide antenna. The design requirements for the refrigeration system and the cryostat are presented. A continuously operating evaporation refrigerator that uses capillary tubing to provide a continuous, self-regulating flow of helium at approximately 1.5 K has been selected as the first refrigerator design for the beam waveguide antenna.

Johnson, D. L.

1986-08-01

173

The 1- to 4-K refrigeration techniques for cooling masers on a beam waveguide antenna  

NASA Technical Reports Server (NTRS)

The status of technology is reported for various 1- to 4-K commercially available refrigeration systems capable of producing 1.5-K refrigeration to cool masers and superconducting cavity oscillators on the proposed beam waveguide antenna. The design requirements for the refrigeration system and the cryostat are presented. A continuously operating evaporation refrigerator that uses capillary tubing to provide a continuous, self-regulating flow of helium at approximately 1.5 K has been selected as the first refrigerator design for the beam waveguide antenna.

Johnson, D. L.

1986-01-01

174

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

175

An investigation of a model of the flow pattern transition mechanism in relation to the identification of annular flow of R134a in a vertical tube using various void fraction models and flow regime maps  

SciTech Connect

In the present study, new experimental data are presented for literature on the prediction of film thickness and identification of flow regime during the co-current downward condensation in a vertical smooth copper tube having an inner diameter of 8.1 mm and a length of 500 mm. R134a and water are used as working fluids in the tube side and annular side of a double tube heat exchanger, respectively. Condensation experiments are done at mass fluxes of 300 and 515 kg m{sup -2} s{sup -1}. The condensing temperatures are between 40 and 50 C; heat fluxes are between 12.65 and 66.61 kW m{sup -2}. The average experimental heat transfer coefficient of the refrigerant HFC-134a is calculated by applying an energy balance based on the energy transferred from the test section. A mathematical model by Barnea et al. based on the momentum balance of liquid and vapor phases is used to determine the condensation film thickness of R134a. The comparative film thickness values are determined indirectly using relevant measured data together with various void fraction models and correlations reported in the open literature. The effects of heat flux, mass flux, and condensation temperature on the film thickness and condensation heat transfer coefficient are also discussed for the laminar and turbulent flow conditions. There is a good agreement between the film thickness results obtained from the theoretical model and those obtained from six of 35 void fraction models in the high mass flux region of R134a. In spite of their different valid conditions, six well-known flow regime maps from the literature are found to be predictive for the annular flow conditions in the test tube in spite of their different operating conditions. (author)

Dalkilic, A.S. [Heat and Thermodynamics Division, Department of Mechanical Engineering, Yildiz Technical University, Yildiz, Besiktas, Istanbul 34349 (Turkey); Wongwises, S. [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab. (FUTURE), Department of Mechanical Engineering, King Mongkut's University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)

2010-09-15

176

The vapor pressure of 1,1,1,2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)  

Microsoft Academic Search

We measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7kPa (corresponding to temperatures in the range 265.6 to 313.2K), additional measurements were made with a

A. R. H. Goodwin; D. R. Defibaugh; L. A. Weber

1992-01-01

177

Evaluation of the protective properties of organic coatings on copper pipes for refrigerator cooling circuit  

Microsoft Academic Search

Copper pipes which are widely used in the refrigerator industry can sometimes work in high humidity atmospheres and in aggressive conditions which can produce dangerous corrosion phenomena of the pipes. Moreover, the design of the refrigerator cooling circuit can introduce some other corrosion problems because copper pipes are frequently in electrical contact with aluminium pipes causing serious galvanic attack on

Lorenzo Fedrizzi; Flavio Deflorian; PierLuigi Bonora

1999-01-01

178

Synthesis of porous cross-linked polymer monoliths using 1,1,1,2-tetrafluoroethane (R134a) as the porogen  

Microsoft Academic Search

In this paper, we describe the synthesis of porous, cross-linked polymethacrylate monoliths by free radical polymerization using 1,1,1,2-tetrafluoroethane (R134a) as the porogenic solvent. Solvent separations were simple (boiling point R134a=?26.5 °C) and the reactions were carried out at relatively low pressures (<20 bar). It was found that the surface area and the median pore diameter of the materials could be varied

Andrew K Hebb; Kazunobu Senoo; Andrew I Cooper

2003-01-01

179

Sub-cooled liquid nitrogen cryogenic system with neon turbo-refrigerator for HTS power equipment  

NASA Astrophysics Data System (ADS)

We developed a prototype sub-cooled liquid nitrogen (LN) circulation system for HTS power equipment. The system consists of a neon turbo-Brayton refrigerator with a LN sub-cooler and LN circulation pump unit. The neon refrigerator has more than 2 kW cooling power at 65 K. The LN sub-cooler is a plate-fin type heat exchanger and is installed in a refrigerator cold box. In order to carry out the system performance tests, a dummy cryostat having an electric heater was set instead of a HTS power equipment. Sub-cooled LN is delivered into the sub-cooler by the LN circulation pump and cooled within it. After the sub-cooler, sub-cooled LN goes out from the cold box to the dummy cryostat, and comes back to the pump unit. The system can control an outlet sub-cooled LN temperature by adjusting refrigerator cooling power. The refrigerator cooling power is automatically controlled by the turbo-compressor rotational speed. In the performance tests, we increased an electric heater power from 200 W to 1300 W abruptly. We confirmed the temperature fluctuation was about ±1 K. We show the cryogenic system details and performance test results in this paper.

Yoshida, S.; Hirai, H.; Nara, N.; Ozaki, S.; Hirokawa, M.; Eguchi, T.; Hayashi, H.; Iwakuma, M.; Shiohara, Y.

2014-01-01

180

Concentration Dependence of Pool Nucleate Boiling Heat Transfer Coefficients for R134a and Polyolester Oil System  

NASA Astrophysics Data System (ADS)

This paper presents experimental results of the concentration dependence of heat transfer coefficients for mixtures of R134a and polyolester (POE) oil under the conditions of pool nuc1eateboiling. The experiments are conducted by means of ah horizontal platinum wire at saturation tel11peraturesof 9, 19, and 29°C and at oil concentrations from 0 to 8 mass%. The present results show that the boiling heat transfer coefficient for the system concerned decreases with increasing oil concentration as a whole but increases slightly at a low oil concentration of about 4 mass%. A correlation equation is also given as a function of heat flux, temperature and oil concentration to reproduce the experimental boiling heat transfer coefficient within an uncertainly of about±15%.

Sato, Tomoaki; Takaishi, Yoshinori; Oguchi, Kosei

181

The vapor pressure of 1,1,1,2-tetrafluoroethane (R134a) and chlorodifluoromethane (R22)  

NASA Astrophysics Data System (ADS)

We measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7kPa (corresponding to temperatures in the range 265.6 to 313.2K), additional measurements were made with a Burnett apparatus. We have combined our results for 1,1,1,2-tetrafluoroethane with those already published from this laboratory at higher pressures to obtain a smoothing equation for the vapor pressure from 215 K to the critical temperature. For chlorodifluoromethane our results have been combined with certain published results to provide an equation for the vapor pressure at temperatures from 217 K to the critical temperature.

Goodwin, A. R. H.; Defibaugh, D. R.; Weber, L. A.

1992-09-01

182

Liquid thermal conductivity of binary mixtures of pentafluoroethane (R125) and 1,1,1,2-tetrafluoroethane (R134a)  

SciTech Connect

Thermal conductivities of zeotropic mixtures of R125 (CF{sub 3}CHF{sub 2}) and R134a (CF{sub 3}CH{sub 2}F) in the liquid phase are reported. Thermal conductivities have been measured by a transient hot-wire method with one bare platinum wire. Measurements have been carried out in the temperature range of 233 to 323 K and in the pressure range of 2 to 20 MPa. The dependence of thermal conductivity on temperature, pressure, and composition of the binary mixture is presented. Measured thermal conductivity data are correlated as a function of temperature, pressure, and overall composition of the mixture. The uncertainty of the measurements was estimated to be better than 2%.

Jeong, S.U.; Kim, M.S.; Ro, S.T. [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering] [Seoul National Univ. (Korea, Republic of). Dept. of Mechanical Engineering

1999-01-01

183

Characterization of refrigerant - 12 gas hydrate formation for heat pump cool storage applications  

Microsoft Academic Search

A latent cool storage system for load management applications is currently under development at Oak Ridge National Laboratory. This system utilizes a refrigerant gas hydrate as the storage medium and incorporates storage directly into the heat pump cycle. This paper reviews the chemistry of gas hydrates, describes the conceptual heat pump\\/cool storage system, and presents the results from experiments performed

1984-01-01

184

Absorption refrigeration method with alternative water-ammonia solution circulation system for microelectronics cooling  

Microsoft Academic Search

The study develops an analytical model of an optimized small scale absorption ammonia\\/water refrigeration system, designed to fit smaller scale power electronics, using a pump to circulate the binary ammonia-water solution cooling agent in the proposed miniaturized system. This continues the authors' previous study of a refrigeration absorption system, by replacing the thermo-siphon and gravitational based circulation of the compensatory

Victor Chiriac; Florea Chiriac

2010-01-01

185

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

186

Continuous Magnetic Refrigerators for Cooling in the 0.05 to 10 K Range  

NASA Technical Reports Server (NTRS)

Low temperature refrigeration is an increasingly vital technology for NASA's Space Science program since most detectors being developed for x-ray, IR and sub-millimeter missions must be cooled to below 100 mK in order to meet the requirements for energy and spatial resolution. For space applications, magnetic refrigeration has an inherent advantage over alternative techniques because it does not depend on gravity. Adiabatic demagnetization refrigerators, or ADRs, are relatively simple, solid state devices. The basic elements are a magnetocaloric refrigerant (usually an encapsulated paramagnetic salt) located in the bore of a superconducting magnet, and a heat switch linking the salt to a heat sink. The alignment of magnetic spins with the magnetic field causes the refrigerant to warm as the magnetic field increases and cool as the field decreases. Thus the simple process of magnetizing the refrigerant to high field with the heat switch closed, then demagnetizing it with the heat switch open allows one to obtain temperatures well below 100 mK using a heat sink as warm as 4.2 K. The refrigerant can maintain a low temperature for a length of time depending on the applied and parasitic heat loads, its mass, and the initial magnetic field strength. Typically ADRs are designed for 12-24 hours of hold time, after which they must be warmed up and recycled.

Shirron, Peter; DiPirro, Michael; Canavan, Edgar; Tuttle, James; Panek, John; Jackson, Michael; King, Todd; Numazawa, Takenori; Krebs, Carolyn (Technical Monitor)

2001-01-01

187

Large cooling power hybrid Gifford mac Mahon / Joule Thomson refrigerator andliquefier  

NASA Astrophysics Data System (ADS)

In this paper, we present two refrigerators using Joule Thomson cycle providing cooling powers of 4.5 W at 4.4 K and using Gifford Mac Mahon cryocoolers for the precooling. Several smaller machines have been developped in our laboratory with refrigeration capacity ranging from 100 mW up to 1.5 W in the temperature range 3 K to 4.4 K. In the present case, to increase the cooling power, we introduced a three stage precooling scheme using a liquid nitrogen vessel plus the two stages of a Gifford Mac Mahon cryocooler. Cooldown and operation of the system are fully automatic. The first refrigerator is used to cool two Nb 3Sn superconducting coils having a maximum field of 11.8 T. The second system is an helium liquefier, designed to produce more than 1 liter per hour.

Poncet, Jean-Marc; Claudet, Gérard; Lagnier, Robert; Ravex, Alain

188

Study of mixed refrigerant undergoing pulsating flow in micro coolers with pre-cooling  

NASA Astrophysics Data System (ADS)

Micro cryogenic coolers can provide low temperatures with a smaller volumetric footprint and smaller power draw than their conventional-scale counterparts. However, they can exhibit lower-than-desired cooling power. We measure the specific cooling power of a refrigerant expanding from a high pressure of 0.6 MPa to a low pressure of 0.1 MPa, while undergoing pulsating flow in a micro cryogenic cooler with pre-cooling. We further observe that the pulses in the flow-rate occur due to a volume of liquid forming in the high-pressure coupling mini-channel. The composition of the flowing refrigerant is analyzed with gas chromatography and thermal conductivity detection (GC/TCD), showing that there is no overall composition change in the refrigerant after it enters the pre-cooling lines. A model of the cooling power under such a pulsating flow regime is developed with good agreement to measured values. An improved refrigerant mixture is designed with this model, and subsequently tested, showing increased specific cooling power.

Lewis, Ryan; Wang, Yunda; Schneider, Hayley; Lee, Y. C.; Radebaugh, Ray

2013-10-01

189

Vapor-liquid equilibrium, coexistence curve, and critical locus for pentafluoroethane + 1,1,1,2-tetrafluoroethane (R125/R134a)  

SciTech Connect

The vapor-liquid equilibrium for pentafluoroethane (R125) + 1,1,1,2-tetrafluoroethane (R134a) was measured along four isotherms between 283 K and 313 K. The vapor-liquid coexistence curve at constant composition near the mixture critical point was measured by the observation of the meniscus disappearance. The critical temperatures and critical densities of the 0.2670 and 0.6648 mole fraction of R125 were determined from the saturation densities along the coexistence curve in the critical region. In addition, the critical locus for the R125/R134a mixture is correlated as a function of composition.

Higashi, Yukihiro [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering] [Iwaki Meisei Univ., Chuodai, Iwaki (Japan). Dept. of Mechanical Engineering

1999-03-01

190

A Unique Approach to Power Electronics and Motor Cooling in a Hybrid Electric Vehicle Environment  

SciTech Connect

An innovative system for cooling the power electronics of hybrid electric vehicles is presented. This system uses a typical automotive refrigerant R-134a (1,1,1,2 tetrafluoroethane) as the cooling fluid in a system that can be used as either part of the existing vehicle passenger air conditioning system or separately and independently of the existing air conditioner. Because of the design characteristics, the cooling coefficient of performance is on the order of 40. Because liquid refrigerant is used to cool the electronics directly, high heat fluxes can result while maintaining an electronics junction temperature at an acceptable value. In addition, an inverter housing that occupies only half the volume of a conventional inverter has been designed to take advantage of this cooling system. Planned improvements should result in further volume reductions while maintaining a high power level.

Ayers, Curtis William [ORNL; Hsu, John S [ORNL; Lowe, Kirk T [ORNL; Conklin, Jim [ORNL

2007-01-01

191

Improvement of Mine Climate by Creating Optimized Conditions for Cooling Fluid Transport and Refrigeration Transfer. Final Report.  

National Technical Information Service (NTIS)

Under this project technical equipment and methods were developed by which cooling fluid transport from the refrigerator to the points of use can be optimized. The approaches comprised minimizing of thermal losses by insulation of the cooling fluid supply...

H. Altena

1986-01-01

192

Defrost gas conditioner for air cooled reverse cycle defrost refrigeration system  

SciTech Connect

This patent describes a reverse cycle defrost refrigeration system having a compressor, an air cooled condenser and evaporator means having surfaces for forming ice thereon during a freezing cycle and arranged to discharge the ice therefrom during a defrost cycle, conduit means for conducting gaseous refrigeration from the compressor to the condenser to be condensed to liquid refrigerant in the condenser and conduit means for conducting the liquid refrigerant to the evaporator means during the freezing cycle, defrost cycle means including a defrost conduit means having defrost solenoid valve connected to the condenser hot gas supply form the compressor and a discharge conduit connected thereto and to the evaporator means to supply hot gaseous refrigerant to the evaporator means during the defrost cycle. The defrost conduit means is connected to the condenser for releasing flash gas from the condenser to the evaporator at the time the defrost solenoid valve opens. The improvement comprises means for conditioning warm defrost gaseous refrigerant which passes back through the discharge conduit to the defrost solenoid valve and the evaporator means at the beginning of the defrost cycle from carrying slugs of liquid refrigerant that may be in the condenser into the discharge conduit and evaporator means and compressor including a liquid separator surge tank and an inlet conduit connected to the top of the surge tank.

Morris, W.F. Jr.

1988-01-19

193

Metered-dose inhaler formulations with beclomethasone-17,21-dipropionate using the ozone friendly propellant R 134a.  

PubMed

Metered-dose inhalers (MDI) are the most widely prescribed devices in the treatment of lung diseases but the continued use of chlorofluorocarbons (CFC) as propellants has made them unpopular due to their influence on the stratospheric ozone layer. The purpose of this study was to show possibilities of formulating beclomethasone-17,21-dipropionate (BDP) with the alternative propellant R 134a as a solution or as a suspension-type metered-dose inhaler. Influencing factors such as surfactant concentration, cosolvent content and actuator tube design were investigated. Metered-dose inhaler formulations were manufactured using a pressure filling technique. The resulting formulations were characterized with regard to their emitted fine particle fraction using the two-stage impinger, BP 93. Fine particle fraction was found to be independent on the surfactant concentration but highly dependent on the cosolvent content and the actuator tube design. In vitro fine particle fractions of 50% were obtained with solution phase MDIs. Formulating BDP as a suspension resulted in unstable dispersions in most cases because of the partial solubility of the drug in the liquified propellant. Stable suspension formulations gave an in vitro fine particle fraction of about 30%. A comparison with established marketed BDP suspension formulations which were found to emit a fine particle fraction in the range 10-50% showed the equivalence of the new CFC-free formulations. PMID:9700025

Steckel, H; Müller, B W

1998-07-01

194

Prediction of heat transfer coefficients and friction factors for evaporation of R-134a flowing inside corrugated tubes  

NASA Astrophysics Data System (ADS)

In this study, experimental and simulation studies of the evaporation heat transfer coefficient and pressure drop of R-134a flowing through corrugated tubes are conducted. The test section is a horizontal counter-flow concentric tube-in-tube heat exchanger 2.0 m in length. A smooth tube and corrugated tubes with inner diameters of 8.7 mm are used as the inner tube. The outer tube is made from a smooth copper tube with an inner diameter of 21.2 mm. The corrugation pitches used in this study are 5.08, 6.35, and 8.46 mm. Similarly, the corrugation depths are 1, 1.25, and 1.5 mm, respectively. The results show that the maximum heat transfer coefficient and pressure drop obtained from the corrugated tube are up to 22 and 19 % higher than those obtained from the smooth tube, respectively. In addition, the average difference of the heat transfer coefficient and pressure drop between the simulation model and experimental data are about 10 and 15 %, respectively.

Laohalertdecha, S.; Aroonrat, K.; Dalkilic, A. S.; Mahian, O.; Kaewnai, S.; Wongwises, S.

2014-04-01

195

Supercritical fluid extraction of polybrominated diphenyl ethers (PBDEs) from house dust with supercritical 1,1,1,2-tetrafluoroethane (R134a)  

Microsoft Academic Search

The extraction of polybrominated diphenyl ethers (PBDEs) from SRM 2585 (Organic Contaminants in House Dust) was investigated using supercritical fluid R134a as an extraction solvent. Three methods of dust extraction were studied: (1) extraction of dry dust, (2) extraction of dry dust dispersed on Ottawa sand and (3) extraction of dust wet with dichloromethane. For each of the three sample

Frank C. Calvosa; Anthony F. Lagalante

2010-01-01

196

Experimental Thermal Conductivity Values for the IUPAC Round-Robin Sample of 1,1,1,2-Tetrafluoroethane (R134a).  

National Technical Information Service (NTIS)

Experimental measurements are reported for the thermal conductivity of 1,1,1,2-tetrafluoroethane (R134a). These measurements were obtained with transient and steady-state hot wires; both bare platinum and anodized tantalum hot wires were used to examine e...

R. A. Perkins A. Laesecke J. Howley M. L. V. Ramires A. N. Gurova L. Cusco

2000-01-01

197

Characterization of refrigerant - 12 gas hydrate formation for heat pump cool storage applications  

SciTech Connect

A latent cool storage system for load management applications is currently under development at Oak Ridge National Laboratory. This system utilizes a refrigerant gas hydrate as the storage medium and incorporates storage directly into the heat pump cycle. This paper reviews the chemistry of gas hydrates, describes the conceptual heat pump/cool storage system, and presents the results from experiments performed to understand and characterize the kinetics of the R-12 gas hydrate formation process.

Ternes, M.P.

1984-02-01

198

Performance evaluation of a monomethylamine–water solar absorption refrigeration system for milk cooling purposes  

Microsoft Academic Search

This study reports the applicability and the theoretical thermodynamic simulation of a solar driven monomethylamine–water single-stage absorption refrigeration cycle for milk cooling purposes in the rural regions of Mexico. A solar heating system using evacuated tube collectors coupled with a conventional auxiliary heating system is proposed. The simulation of the yearly dynamic behaviour of the solar system is carried out

I. Pilatowsky; W. Rivera; J. R. Romero

2004-01-01

199

Cooling of superconducting devices by liquid storage and refrigeration unit  

SciTech Connect

A system is disclosed for cooling superconducting devices. The system includes a cryogen cooling system configured to be coupled to the superconducting device and to supply cryogen to the device. The system also includes a cryogen storage system configured to supply cryogen to the device. The system further includes flow control valving configured to selectively isolate the cryogen cooling system from the device, thereby directing a flow of cryogen to the device from the cryogen storage system.

Laskaris, Evangelos Trifon; Urbahn, John Arthur; Steinbach, Albert Eugene

2013-08-20

200

THERMODYNAMIC EVALUATION OF FIVE ALTERNATIVE REFRIGERANTS IN VAPOR-COMPRESSION CYCLES  

EPA Science Inventory

The paper gives results of a thermodynamic evaluation of five alternative refrigerants in a vapor-compression refrigeration cycle, utilizing throttling, super-heating, and combined throttling and superheating. ive alternative refrigerants (R32, R125, R134a, R143a, and R152a) were...

201

Study of a Vuilleumier cycle cryogenic refrigerator for detector cooling on the limb scanning infrared radiometer  

NASA Technical Reports Server (NTRS)

A program to detect and monitor the presence of trace constituents in the earth's atmosphere by using the Limb Scanning Infrared Radiometer (LSIR) is reported. The LSIR, which makes radiometric measurements of the earth's limb radiance profile from a space platform, contains a detector assembly that must be cooled to a temperature of 65 + or - 2 K. The feasibility of cooling the NASA-type detector package with Vuilleumier (VM) cryogenic refrigerator was investigated to develop a preliminary conceptual design of a VM refrigerator that is compatible with a flight-type LSIR instrument. The scope of the LSIR program consists of analytical and design work to establish the size, weight, power consumption, interface requirements, and other important characteristics of a cryogenic cooler that would meet the requirements of the LSIR. The cryogenic cooling requirements under the conditions that NASA specified were defined. Following this, a parametric performance analysis was performed to define the interrelationships between refrigeration characteristics and mission requirements. This effort led to the selection of an optimum refrigerator design for the LSIR mission.

Russo, S. C.

1976-01-01

202

Operation of an X-ray Transition-Edge Sensor Cooled by Tunnel Junction Refrigerators  

Microsoft Academic Search

We demonstrate successful cooling of an X-ray transition-edge sensor (TES) using solid-state refrigerators based on normal-metal\\/insulator\\/superconductor\\u000a (NIS) tunnel junctions. Above the TES transition temperature (T\\u000a \\u000a c\\u000a ), we use Johnson-noise thermometry to measure the cooling performance. In this regime, the NIS refrigerators cool the TES\\u000a from 300 mK to 220 mK and from 220 mK to T\\u000a \\u000a c\\u000a =160 mK. Below T\\u000a \\u000a c\\u000a ,

N. A. Miller; J. A. Beall; G. C. Hilton; K. D. Irwin; G. C. O’Neil; D. R. Schmidt; L. R. Vale; J. N. Ullom

2008-01-01

203

High sensitivity spectroscopic and thermal characterization of cooling efficiency for optical refrigeration materials  

NASA Astrophysics Data System (ADS)

Since recent demonstration of cryogenic optical refrigeration, a need for reliable characterization tools of cooling performance of different materials is in high demand. We present our experimental apparatus that allows for temperature and wavelength dependent characterization of the materials' cooling efficiency and is based on highly sensitive spectral differencing technique or two-band differential spectral metrology (2B-DSM). First characterization of a 5% w.t. ytterbium-doped YLF crystal showed quantitative agreement with the current laser cooling model, as well as measured a minimum achievable temperature (MAT) at 110 K. Other materials and ion concentrations are also investigated and reported here.

Melgaard, Seth D.; Seletskiy, Denis V.; di Lieto, Alberto; Tonelli, Mauro; Sheik-Bahae, Mansoor

2012-02-01

204

Experimental investigation of heat transfer coefficient of R134a during condensation in vertical downward flow at high mass flux in a smooth tube  

Microsoft Academic Search

The two-phase heat transfer coefficients of pure HFC-134a condensing inside a smooth tube-in-tube heat exchanger are experimentally investigated. The test section is a 0.5 m long double tube with refrigerant flowing in the inner tube and cooling water flowing in the annulus. The inner tube is constructed from smooth copper tubing of 9.52 mm outer diameter and 8.1 mm inner diameter. The test

A. S. Dalkilic; S. Laohalertdecha; S. Wongwises

2009-01-01

205

Experimental investigation on condensation heat transfer of R134a on single horizontal copper and stainless steel three-dimensional finned tubes  

NASA Astrophysics Data System (ADS)

Condensation heat transfer characteristics of R134a on the horizontal copper and stainless steel three-dimensional (3D) finned tubes are experimentally investigated. The objective is to obtain the basic data for film condensation of R134a on low and high thermal conductivity 3D enhanced tubes. Experiments were carried out at saturation temperatures of 39 °C and wall subcoolings from 3.2 to 10.5 °C. The results show that the condensation heat transfer coefficients on the smooth copper and stainless steel tubes are smaller than those predicted by the Nusselt analysis by 4.4% and 4.8%, respectively. The average enhancement factors provided by the copper and stainless steel 3D finned tubes are 7.86 and 3.34, respectively. The copper 3D finned tube has higher enhancement factor than that of the stainless steel 3D finned tube, due to its high fin and thermal conductivity.

Qin, Peng; Zhang, Zhengguo; Xu, Tao; Gao, Xuenong; Wang, Shuangfeng

2013-07-01

206

Characterization of diabatic two-phase flows in microchannels: Flow parameter results for R-134a in a 0.5 mm channel  

Microsoft Academic Search

An optical measurement method for two-phase flow pattern characterization in microtubes has been utilized to determine the frequency of bubbles generated in a microevaporator, the coalescence rates of these bubbles and their length distribution as well as their mean velocity. The tests were run in a 0.5mm glass channel using saturated R-134a at 30°C (7.7bar). The optical technique uses two

Rémi Revellin; Vincent Dupont; Thierry Ursenbacher; John R. Thome; Iztok Zun

2006-01-01

207

Measurements of the viscosity of R134a and R32 in the temperature range 270–340 K at pressures up to 20 MPa  

Microsoft Academic Search

This paper reports new measurements of the liquid viscosity of R134a and R32 in the temperature range 270 to 340 K and pressures up to 20 MPa. The measurements have been carried out in a vibrating-wire instrument calibrated with respect to the standard reference value of the viscosity of water. It is estimated that the uncertainty of the present viscosity

M. J. Assael; J. H. Dymond; S. K. Polimatidou

1994-01-01

208

Experimental investigation of convective heat transfer coefficient during downward laminar flow condensation of R134a in a vertical smooth tube  

Microsoft Academic Search

This paper presents an experimental investigation of laminar film condensation of R134a in a vertical smooth tube having an inner diameter of 7-8.1 mm and a length of 500 mm. Condensation experiments were performed at mass fluxes of 29 and 263 kg m ? 2 s ? 1 . The pressures were between 0.77 and 0.1 MPa. The heat transfer

A. S. Dalkilic; S. Yildiz; S. Wongwises

2009-01-01

209

Experimental evaluation of a vapour compression plant performance using R134a, R407C and R22 as working fluids  

Microsoft Academic Search

In this paper, the influence of the main operating variables on the energetic characteristics of a vapour compression plant, based on experimental results, is addressed. The experimental tests are performed on a single-stage vapour compression plant using three different working fluids, R134a, R407C and R22. The operating variables considered are the evaporating pressure, the condensing pressure and the superheating degree

R Cabello; E Torrella; J Navarro-Esbr??

2004-01-01

210

An investigation on void fraction of vapor–liquid two-phase flow for smooth and microfin tubes with R134a at adiabatic condition  

Microsoft Academic Search

The present paper deals with experiments and a prediction method for the void fraction of R134a vapor–liquid two-phase flow in horizontal smooth and microfin tubes in adiabatic condition. The void fraction is measured by the quick closing valve method. The smooth tube tested is 1024 mm in length and 7.52 mm in inside diameter. The microfin tube tested is 1015

Shigeru Koyama; Joodong Lee; Ryuuichirou Yonemoto

2004-01-01

211

Flow condensation heat transfer coefficients of R22, R134a, R407C, and R410A inside plain and microfin tubes  

Microsoft Academic Search

Flow condensation heat transfer coefficients (HTCs) of R22, R134a, R407C, and R410A inside horizontal plain and microfin tubes of 9.52 mm outside diameter and 1 m length were measured at the condensation temperature of 40 °C with mass fluxes of 100, 200, and 300 kg m?2 s?1 and a heat flux of 7.7–7.9 kW m?2. For a plain tube, HTCs of

Dongsoo Jung; Youngmok Cho; Kiho Park

2004-01-01

212

Effect of flow topology on the calculation of two-phase frictional multipliers in uniformly heated flow of R-134a in a rectangular duct  

Microsoft Academic Search

The two-phase frictional multipliers for SUVA R-134a flowing in a rectangular duct (with D{sub H} = 4.8 mm) have been measured for three nominal system pressures (0.88, 1.34 and 2.34 MPa) and four nominal mass fluxes (510, 1020 and 1740, 2040 kg\\/m²\\/s) under uniform heat flux conditions. The data is compared with adiabatic data previously taken at similar flow conditions,

Peter Vassallo; W. Kevin Cope; Walter C. Smith

2010-01-01

213

Effect of flow topology on the calculation of two-phase frictional multipliers in uniformly heated flow of R-134a in a rectangular duct  

Microsoft Academic Search

The two-phase frictional multipliers for SUVA R-134a flowing in a rectangular duct (with DH=4.8mm) have been measured for three nominal system pressures (0.88, 1.34 and 2.34MPa) and four nominal mass fluxes (510, 1020 and 1740, 2040kg\\/m2\\/s) under uniform heat flux conditions. The data is compared with adiabatic data previously taken at similar flow conditions, as well as with several classical

Peter Vassallo; W. Kevin Cope; Walter C. Smith

2010-01-01

214

Experimental investigations of the post-CHF heat transfer of R-134a flow boiling in an annulus with spacer grids  

Microsoft Academic Search

An experimental study was performed using R-134a in an annulus channel to investigate the heat transfer characteristics in the post-CHF region. The experiments were conducted under the outlet pressures of 1.1–2.0MPa, the mass fluxes of 100–400kg\\/m2s and the inlet temperatures of 25–51°C. Experiments were conducted in three cases of the annular channel test without spacers, the test with I-type spacer

Kwi Lim Lee; Soon Heung Chang

2010-01-01

215

The Effects of Swirl Flow on CHF by Various Spacer Grids in 2*2 Rod Bundle with R-134a  

Microsoft Academic Search

Experimental works have shown that the effect of swirl flow on CHF by various spacer grid in the 2*2 rod bundle with R-134a. Test spacer grids have mixing vanes for generating swirl flow. The geometries of test section are as follows; rod diameter is 9.5 mm, rod pitch is 12.85 mm. For test spacer grid, two different types are used

Byung Soo Shin; Soon Heung Chang

2004-01-01

216

Supercritical fluid extraction of polybrominated diphenyl ethers (PBDEs) from house dust with supercritical 1,1,1,2-tetrafluoroethane (R134a).  

PubMed

The extraction of polybrominated diphenyl ethers (PBDEs) from SRM 2585 (Organic Contaminants in House Dust) was investigated using supercritical fluid R134a as an extraction solvent. Three methods of dust extraction were studied: (1) extraction of dry dust, (2) extraction of dry dust dispersed on Ottawa sand and (3) extraction of dust wet with dichloromethane. For each of the three sample preparation methods, extracts at three temperatures (110, 150, and 200 degrees C) above the critical temperature of R134a were performed. Eight PBDE congeners (BDE-28, -47, -99, 100, -153, -154, -183, and -209) in the SFE extracts were analyzed by liquid chromatography negative-ion atmospheric pressure photoionization tandem mass spectrometry (LC/NI-APPI/MS/MS). The optimum extraction of PBDEs from house dust using supercritical R134a is obtained when the dust is pre-wet with dichloromethane prior to extraction to swell the dust. For all sample preparation methods, higher temperatures afforded higher percent recoveries of the eight PBDE congeners. Only a combination of high-temperature (200 degrees C) and pre-wetting the dust with dichloromethane produced high recovery of the environmentally important, fully brominated PBDE congener, BDE-209. PMID:20006061

Calvosa, Frank C; Lagalante, Anthony F

2010-01-15

217

Experimental Study on the Novel Solar Adsorption Refrigeration Cooling Tube  

Microsoft Academic Search

Using solar light as energy and compound adsorbent\\/water as working pair, the novel solar cooling tube was made and experimental studied in this paper. The experimental results show that, when the solar radiation was about 19.6-21.9 MJ-d-1m-2 at the daytime, the temperature of adsorbent bed could reached to 220degC, the condensation temperature was about 45degC. In the nighttime, the evaporator

Zhao Hui-Zhong; Zhang Min; Yu Guo-Qing; Lv Jing; Liu Zhenyan

2009-01-01

218

A closed-cycle refrigerator for cooling maser amplifiers below 4 Kelvin  

NASA Technical Reports Server (NTRS)

A helium refrigerator utilizing the Gifford-McMahon/Joule-Thomson (GM/JT) cycle was designed and tested to demonstrate the feasibility of using small closed-cycle refrigerators as an alternative to batch-filled cryostats for operating temperatures below 4 K. The systems could be used to cool low-noise microwave maser amplifiers located in large parabolic antennas. These antennas tilt vertically, making conventional liquid-filled dewars difficult to use. The system could also be used for a non-tilting beam waveguide antenna to reduce the helium consumption of a liquid helium cryostat. The prototype system is adjustable to provide 700 mW of cooling at 2.5 K to 3 W at 4.3 K. Performance of the unit is not significantly affected by physical orientation. The volume occupied by the refrigerator is less than 0.1 cu m. Two JT expansion stages are used to maximize cooling capacity per unit mass flow. The heat exchangers were designed to produce minimum pressure drop in the return gas stream. Pressure drop for the entire JT return circuit is less than 5 kpa at a mass flow of 0.06 g/sec when operating at 2.5 K.

Britcliffe, M.

1989-01-01

219

A closed-cycle refrigerator for cooling maser amplifiers below 4 Kelvin  

NASA Astrophysics Data System (ADS)

A helium refrigerator utilizing the Gifford-McMahon/Joule-Thomson (GM/JT) cycle was designed and tested to demonstrate the feasibility of using small closed-cycle refrigerators as an alternative to batch-filled cryostats for operating temperatures below 4 K. The systems could be used to cool low-noise microwave maser amplifiers located in large parabolic antennas. These antennas tilt vertically, making conventional liquid-filled dewars difficult to use. The system could also be used for a non-tilting beam waveguide antenna to reduce the helium consumption of a liquid helium cryostat. The prototype system is adjustable to provide 700 mW of cooling at 2.5 K to 3 W at 4.3 K. Performance of the unit is not significantly affected by physical orientation. The volume occupied by the refrigerator is less than 0.1 cu m. Two JT expansion stages are used to maximize cooling capacity per unit mass flow. The heat exchangers were designed to produce minimum pressure drop in the return gas stream. Pressure drop for the entire JT return circuit is less than 5 kpa at a mass flow of 0.06 g/sec when operating at 2.5 K.

Britcliffe, M.

1989-08-01

220

Support of NASA ADR/ Cross-Enterprise NRA Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling from 10K to 50mK, Development of a Heat Switch.  

National Technical Information Service (NTIS)

Mechanical heat switches are used in conjunction with sorption refrigerators, adiabatic demagnetization refrigerators and for other cryogenic tasks including the pre-cooling cryogenic systems. They use a mechanical actuator which closes Au plated Cu jaws ...

P. L. Richards

2005-01-01

221

R&D on The Cooling Systems Using Natural Refrigerants  

NASA Astrophysics Data System (ADS)

The use of waste heat of low temperatures is an important problem from the environmental considerations. Notice that adsorption cycles have a distinct advantage over other systems of their ability to produce cooling by using low waste heat as 60 to 80°C and also being absolutely benign for the environment. However the present available adsorption chillers are still heavier and larger in size. Hence their compactness and cost reduction as well as higher efficiency are urgent tasks for wider use. This review discusses recent development on adsorption heat pumps as well as forthcoming applications. The sources are mainly papers and discussions at the IEA Annex 24 Workshop in Turin, Italy (1999), FOA6 (Fundamental of Adsorption) Conference in Presquile de Giens, France (1998) and ISHPC (International Sorption Heat Pump Conference) in Munich, Germany (1999).

Yanagi, Hideharu

222

Evaporation heat transfer and friction characteristics of R-134a flowing downward in a vertical corrugated tube  

SciTech Connect

Differently from most previous studies, the heat transfer and friction characteristics of the pure refrigerant HFC-134a during evaporation inside a vertical corrugated tube are experimentally investigated. The double tube test sections are 0.5 m long with refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tubes are one smooth tube and two corrugated tubes, which are constructed from smooth copper tube of 8.7 mm inner diameter. The test runs are performed at evaporating temperatures of 10, 15, and 20 C, heat fluxes of 20, 25, and 30 kW/m{sup 2}, and mass fluxes of 200, 300, and 400 kg/m{sup 2} s. The quality of the refrigerant in the test section is calculated using the temperature and pressure obtained from the experiment. The pressure drop across the test section is measured directly by a differential pressure transducer. The effects of heat flux, mass flux, and evaporation temperature on the heat transfer coefficient and two-phase friction factor are also discussed. It is found that the percentage increases of the heat transfer coefficient and the two-phase friction factor of the corrugated tubes compared with those of the smooth tube are approximately 0-10% and 70-140%, respectively. (author)

Aroonrat, Kanit; 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 10140 (Thailand)

2011-01-15

223

Performance prediction of refrigerant-DMF solutions in a single-stage solar-powered absorption refrigeration system at low generating temperatures  

SciTech Connect

A theoretical analysis of the coefficient of performance was undertaken to examine the efficiency characteristics of R22 + DMF, R134a + DMF, R32 + DMF as working fluids, respectively, for a single-stage and intermittent absorption refrigerator which allows the use of heat pipe evacuated tubular collectors. The modeling and simulation of the performance considers both solar collector system and the absorption cooling system. The typical meteorological year file containing the weather parameters for Hangzhou is used to simulate the system. The results show that the system is in phase with the weather. In order to increase the reliability of the system, a hot water storage tank is essential. The optimum ratio of storage tank per solar collector area for Hangzhou's climate for a 1.0 kW system is 0.035-0.043L. Considering the relative low pressure and the high coefficient of performance, R134a + DMF mixture presents interesting properties for its application in solar absorption cycles at moderate condensing and absorbing temperatures when the evaporating temperatures in the range from 278 K to 288 K which are highly useful for food preservation and for air-conditioning in rural areas. (author)

He, L.J. [Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027 (China); Institute of Environment and Energy, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Tang, L.M.; Chen, G.M. [Institute of Refrigeration and Cryogenics, Zhejiang University, Hangzhou 310027 (China)

2009-11-15

224

The natural fluid nitrous oxide—an option as substitute for low temperature synthetic refrigerants  

Microsoft Academic Search

A theoretical investigation was performed concerning the coefficient of performance (COP) of cascade refrigerating systems using N2O as refrigerant for the low temperature cascade stage and various natural refrigerants like ammonia, propane, propene, carbon dioxide and nitrous oxide itself for the high temperature stage. The basis of the comparison was a conventional R23\\/R134a-cascade refrigerating system for heat rejection temperatures of

H. Kruse; H. Rüssmann

2006-01-01

225

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

226

A Robust Cooling Platform for NIS Junction Refrigeration and sub-Kelvin Cryogenic Systems  

NASA Astrophysics Data System (ADS)

Recent advances in Normal metal-insulator-superconductor (NIS) tunnel junctions (Clark et al. Appl Phys Lett 86: 173508, 2005, Appl Phys Lett 84: 4, 2004) have proven these devices to be a viable technology for sub-Kelvin refrigeration. NIS junction coolers, coupled to a separate cold stage, provide a flexible platform for cooling a wide range of user-supplied payloads. Recently, a stage was cooled from 290 to 256 mK (Lowell et al. Appl Phys Lett 102: 082601 2013), but further mechanical and electrical improvements are necessary for the stage to reach its full potential. We have designed and built a new Kevlar suspended cooling platform for NIS junction refrigeration that is both lightweight and well thermally isolated; the calculated parasitic loading is < 300 pW from 300 to 100 mK. The platform is structurally rigid with a measured deflection of 25 \\upmu m under a 2.5 kg load and has an integrated mechanical heat switch driven by a superconducting stepper motor with thermal conductivity G = 4.5 × 10^{-7} W/K at 300 mK. An integrated radiation shield limits thermal loading and a modular platform accommodates enough junctions to provide nanowatts of continuous cooling power. The compact stage size of 7.6 cm × 8.6 cm × 4.8 cm and overall radiation shield size of 8.9 cm × 10.0 cm × 7.0 cm along with minimal electrical power requirements allow easy integration into a range of cryostats. We present the design, construction, and performance of this cooling platform as well as projections for coupling to arrays of NIS junctions and other future applications.

Wilson, B.; Atlas, M.; Lowell, P.; Moyerman, S.; Stebor, N.; Ullom, J.; Keating, B.

2014-02-01

227

Performances of the mixed-gases Joule–Thomson refrigeration cycles for cooling fixed-temperature heat loads  

Microsoft Academic Search

Numerous mixed-gases refrigeration cycle configurations based on Joule–Thomson effects were developed in the past several decades. In this paper, comprehensive thermodynamic analyses were made on two typical cycle configurations to learn their performance for cooling fixed-temperature heat loads. One is the single-stage cycle without phase separators; the other is the auto-cascade refrigeration cycle which has at least one phase separator.

M. Q. Gong; J. F. Wu; E. G. Luo

2004-01-01

228

Continuous Magnetic Refrigerators for Cooling in the 0.05 to 10 K Range: Progress and Future Development  

NASA Technical Reports Server (NTRS)

Low temperature refrigeration is an increasingly vital technology for NASA s Space Science program since most detectors being developed for x-ray, IR and sub-millimeter missions must be cooled to below 100 mK in order to meet the requirements for energy and spatial resolution. For space applications, magnetic refrigeration has an inherent advantage over alternative techniques because it does not depend on gravity. Adiabatic demagnetization refrigerators, or ADRs, are relatively simple, solid state devices. The basic elements are a magnetocaloric refrigerant (usually an encapsulated paramagnetic salt) located in the bore of a superconducting magne$, and a heat switch linking the salt to a heat sink. The alignment of magnetic spins with the magnetic field causes the refrigerant to warm as the magnetic field increases and cool as the field decreases. Thus the simple process of magnetizing the refrigerant to high field with the heat switch closed, then demagnetizing it with the heat switch open allows one to obtain temperatures well below 100 mK using a heat sink as warm as 4.2 K. The refrigerant can maintain a low temperature for a length of time depending on the applied and parasitic heat loads, its mass, and the initial magnetic field strength. Typically ADRs are designed for 12-24 hours of hold time, after which they must be warmed up and recycled. The drawback to single-shot ADRs is that the cooling power per unit mass is relatively low. Refrigerants that are suitable for low temperature operation necessarily have low magnetic ion density, and therefore low entropy density. Since ADRs store entropy, systems with even modest cooling powers (a few microwatts) at temperatures below 100 mK tend to be massive, averaging 10-15 kg.

Shirron, Peter; DiPirro, Michael; Canavan, Edgar; Tuttle, James; King, Todd; Numazawa, Takenori

2003-01-01

229

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

230

A Superfluid Pulse Tube Refrigerator Without Moving Parts for Sub-Kelvin Cooling  

NASA Technical Reports Server (NTRS)

A report describes a pulse tube refrigerator that uses a mixture of He-3 and superfluid He-4 to cool to temperatures below 300 mK, while rejecting heat at temperatures up to 1.7 K. The refrigerator is driven by a novel thermodynamically reversible pump that is capable of pumping the He-3 He-4 mixture without the need for moving parts. The refrigerator consists of a reversible thermal magnetic pump module, two warm heat exchangers, a recuperative heat exchanger, two cold heat exchangers, two pulse tubes, and an orifice. It is two superfluid pulse tubes that run 180 out of phase. All components of this machine except the reversible thermal pump have been demonstrated at least as proof-of-concept physical models in previous superfluid Stirling cycle machines. The pump consists of two canisters packed with pieces of gadolinium gallium garnet (GGG). The canisters are connected by a superleak (a porous piece of VYCOR glass). A superconducting magnetic coil surrounds each of the canisters.

Miller, Franklin K.

2012-01-01

231

The development of high cooling power and low ultimate temperature superfluid Stirling refrigerators  

NASA Astrophysics Data System (ADS)

The superfluid Stirling refrigerator (SSR) is a recuperative Stirling cycle refrigerator which provides cooling to below 2 K by using a liquid 3He-4He mixture as the working fluid. In 1990, Kotsubo and Swift demonstrated the first SSR, and by 1995, Brisson and Swift had developed an experimental prototype capable of reaching a low temperature of 296 mK. The goal of this thesis was to improve these capabilities by developing a better understanding of the SSR and building SSR's with higher cooling powers and lower ultimate temperatures. This thesis contains four main parts. In the first part, a numerical analysis demonstrates that the optimal design and ultimate performance of a recuperative Stirling refrigerator is fundamentally different from that of a standard regenerative Stirling refrigerator due to a mass flow imbalance within the recuperator. The analysis also shows that high efficiency recuperators remain a key to SSR performance. Due to a quantum effect called Kapitza resistance, the only realistic and economical method of creating higher efficiency recuperators for use with an SSR is to construct the heat exchangers from very thin (12 ?m - 25 ?m thick) plastic films. The second part of this thesis involves the design and construction of these recuperators. This research resulted in Kapton heat exchangers which are leaktight to superfluid helium and capable of surviving repeated thermal cycling. In the third part of this thesis, two different single stage SSR's are operated to test whether the plastic recuperators would actually improve SSR performance. Operating from a high temperature of 1.0 K and with 1.5% and 3.0% 3He-4He mixtures, these SSR's achieved a low temperature of 291 mK and delivered net cooling powers of 3705 ?W at 750 mK, 977 ?W at 500 mK, and 409 ?W at 400 mK. Finally, this thesis describes the operation of three versions of a two stage SSR. Unfortunately, due to experimental difficulties, the merits of a two stage SSR were not demonstrated and further work is still required. However, despite these difficulties, one of the two stage SSR's was able to reach an ultimate low temperature of 248 mK from a high temperature of 1.03 K. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Patel, Ashok B.

232

Current and future miniature refrigeration cooling technologies for high power microelectronics  

Microsoft Academic Search

Utilizing refrigeration may provide the only means by which future high-performance electronic chips can be maintained below predicted maximum temperature limits. Widespread application of refrigeration in electronic packaging will remain limited, until the refrigerators can be made sufficiently small so that they can be easily incorporated within the packaging. A review of existing microscale and mesoscale refrigeration systems revealed that

Patrick E. Phelan; Victor A. Chiriac; Tien-Yu Tom Lee

2002-01-01

233

Flow boiling heat transfer of R134a and R404A in a microfin tube at low mass fluxes and low heat fluxes  

NASA Astrophysics Data System (ADS)

An experimental investigation of flow boiling heat transfer in a commercially available microfin tube with 9.52 mm outer diameter has been carried out. The microfin tube is made of copper with a total fin number of 55 and a helix angle of 15°. The fin height is 0.24 mm and the inner tube diameter at fin root is 8.95 mm. The test tube is 1 m long and is electrically heated. The experiments have been performed at saturation temperatures between 0 and -20°C. The mass flux was varied between 25 and 150 kg/m2s, the heat flux from 15,000 W/m2 down to 1,000 W/m2. All measurements have been performed at constant inlet vapour quality ranging from 0.1 to 0.7. The measured heat transfer coefficients range from 1,300 to 15,700 W/m2K for R134a and from 912 to 11,451 W/m2K for R404A. The mean heat transfer coefficient of R134a is in average 1.5 times higher than for R404A. The mean heat transfer coefficient has been compared with the correlations by Koyama et al. and by Kandlikar. The deviations are within ±30% and ±15%, respectively. The influence of the mass flux on the heat transfer is most significant between 25 and 62.5 kg/m2s, where the flow pattern changes from stratified wavy flow to almost annular flow. This flow pattern transition is shifted to lower mass fluxes for the microfin tube compared to the smooth tube.

Spindler, Klaus; Müller-Steinhagen, Hans

2009-05-01

234

Compatibility of refrigerants and lubricants with motor materials under retrofit conditions  

SciTech Connect

Motor materials were exposed to original refrigerants R-11, R-12, R-22 and R-502 in the presence of mineral oil for 500 hours. These same materials were then exposed to alternative refrigerants R-123, R-134a, R-407C (R-32/R-125/R-134a) and R-404A (R-125/R-143a/R-134a), respectively, in the presence of the appropriate lubricant for 500 hours. As a control, some samples were exposed to the original refrigerant/mineral oil for a total of 1,000 hours. These tests were conducted to determine whether exposure to the original refrigerant/mineral oil would affect compatibility of the motor materials with the alternative refrigerant/lubricant after retrofit. Motor materials exposed to the alternative refrigerant and lubricant (after an initial exposure to the original refrigerant and mineral oil) appeared to be compatible with the alternative refrigerant and lubricant. The only concerns were embrittlement of the polyethylene terephthalate (PET) sheet and sleeving insulations, and delamination and blistering of the Nomex sheet insulation in the R-22, R-502, and R-12. Embrittlement of the PET materials was attributed to moisture present during the exposure. Separation of the 475 varnish from metal surfaces in the R-123 was also a concern. The sheet and sleeving insulations were affected by the original refrigerant/mineral oil to a greater extent than by the alternative refrigerant and lubricant.

Doerr, R.; Waite, T. [Trane Co., La Crosse, WI (United States)

1995-01-12

235

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

236

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

237

Experimental measurement of vapor pressures and (vapor + liquid) equilibrium for {1,1,1,2-tetrafluoroethane (R134a) + propane (R290)} by a recirculation apparatus with view windows  

Microsoft Academic Search

The saturated vapor pressures of 1,1,1,2-tetrafluoroethane (R134a) and propane (R290), and the (vapor+liquid) equilibrium (VLE) data at (255.000, 265.000, 275.000, and 285.000)K for the (R134a+R290) system were measured by a recirculation apparatus with view windows. The uncertainty of the temperatures, pressures, and compositions are less than ±5mK, ±0.0005MPa, and ±0.005, respectively. The saturated vapor pressures data were correlated by a

Xueqiang Dong; Maoqiong Gong; Junsheng Liu; Jianfeng Wu

2011-01-01

238

Modeling solar-driven ejector refrigeration system offering air conditioning for office buildings  

Microsoft Academic Search

A lumped method combined with dynamic model is proposed for use in investigating the performance and solar fraction of a solar-driven ejector refrigeration system (SERS) using R134a, for office air conditioning application for buildings in Shanghai, China. Classical hourly outdoor temperature and solar radiation model were used to provide basic data for accurate analysis of the system performance. Results indicate

J. Guo; H. G. Shen

2009-01-01

239

Horizontal Convective Condensation of Alternative Refrigerants within a Micro-Fin Tube.  

National Technical Information Service (NTIS)

This paper presents local convective condensation measurements for four refrigerants: R134a, R410A(R32/R125, 50/50 % mass), R125, and R32 in a micro-fin tube. Both heat transfer and pressure drop measurements are provided. The heat transfer degradation as...

M. A. Kedzierski J. M. Goncalves

1997-01-01

240

Literature survey on thermophysical properties of refrigerants  

SciTech Connect

A bibliographic compilation is given on thermophysical properties of the environmentally acceptable hydrofluorocarbon blends R404A, R407C, and R410A. These refrigerant blends are still under investigation and meant to replace the transitional hydrochlorofluorocarbon R22 and the azeotrope R502. In a second part reliable formulations to calculate thermophysical-property surfaces of some selected well investigated fluids used in refrigeration are recommended. The fluids water, air, carbon dioxide, ammonia, R134a, R123, and R152a are subjects of that part.

Krauss, R.; Stephan, K. [Univ. Stuttgart (Germany). Inst. fuer Technische Thermodynamik and Thermische Verfahrenstechnik

1998-11-01

241

Literature Survey on Thermophysical Properties of Refrigerants  

NASA Astrophysics Data System (ADS)

A bibliographic compilation is given on thermophysical properties of the environmentally acceptable hydrofluorocarbon blends R404A, R407C, and R410A. These refrigerant blends are still under investigation and meant to replace the transitional hydrochlorofluorocarbon R22 and the azeotrope R502. In a second part reliable formulations to calculate thermophysical-property surfaces of some selected well investigated fluids used in refrigeration are recommended. The fluids water, air, carbon dioxide, ammonia, R134a, R123, and R152a are subjects of that part.

Krauss, R.; Stephan, K.

1998-11-01

242

Modeling of Solar-Powered Single-Effect Absorption Cooling System and Supermarket Refrigeration\\/HVAC System  

Microsoft Academic Search

This thesis consists of two different research problems. In the first one, the aim is to model and simulate a solar-powered, single-effect, absorption refrigeration system using a flat-plate solar collector and LiBr-H2O mixture as the working fluid. The cooling capacity and the coefficient of performance of the system are analyzed by varying all independent parameters, namely: evaporator pressure, condenser pressure,

Ammar Bahman

2011-01-01

243

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

244

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

245

Experimental investigation of velocity and length of elongated bubbles for flow of R-134a in a 0.5 mm microchannel  

SciTech Connect

The length and velocity of elongated bubbles have been experimentally investigated for R-134a flowing in a 0.5 mm microchannel, where 440 experimental data points were obtained at the exit of a microevaporator using an optical laser measurement technique. The variation of the elongated bubble velocity u{sub v} as a function of its length L{sub v} shows firstly, a nearly linear increase of u{sub v} with L{sub v} and secondly, a region where the velocity tends towards a plateau and where it varies little with further increase in length. This behavior is the starting point to explain merging between elongated bubbles in microchannels during flow boiling. No influence of a small variation in the inlet subcooling (ranging from 2 to 5 C) and the microevaporator length (ranging from 30 to 70 mm) was observed on the bubble velocity and the bubble length. On the other hand, when decreasing the saturation temperature, the bubble length and the bubble velocity both increased due to the decrease in the vapor density. Almost 92% of the new database obtained here is predicted by the elongated bubble velocity model of Agostini et al. [B. Agostini, R. Revellin, J.R. Thome, Elongated bubbles in microchannels. Part I: Experimental study and modelisation of elongated bubble velocity. Int. J. Multiphase Flow, in press] within a {+-}20% error band. Furthermore, this model shows that during diabatic flow boiling of elongated bubbles in horizontal microchannels, the drift flux distribution parameter C is close to unity and the drift velocity is not necessarily equal to zero as predicted by the original drift flux model of Zuber and Findlay [N. Zuber, J.A. Findlay, Average volumetric concentration in two-phase flow systems. J. Heat Transfer 87 (1965) 458-463]. Rather the drift velocity can deviate substantially from the average bubble velocity given by the homogeneous model. (author)

Revellin, Remi [Centre de Thermique de Lyon (CETHIL), UMR 5008 CNRS-INSA-Univ. Lyon 1, Bat. Sadi Carnot, INSA-Lyon, F-69621 Villeurbanne Cedex (France); Agostini, Bruno [ABB Switzerland Ltd., Corporate Research, Segelhofstrasse 1 K/P.O. Box, CH-5405 Baden 5 Daettwil (Switzerland); Ursenbacher, Thierry; Thome, John R. [EPFL STI ISE LTCM, ME G1 464, Station 9, CH-1015 Lausanne (Switzerland)

2008-01-15

246

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

247

An Investigation of Refrigerant Void Fraction in Horizontal, Microfin Tubes  

Microsoft Academic Search

A series of experiments to determine void fraction in both condensation and evaporation have been performed in horizontal microfin tubes with refrigerants R134a and R410A. Mass flux varied from 75 kg\\/m·s to 700 kg\\/m·s and average test section quality varied from 5% to 80%. Zero degree (axial grooving) and 18 degree helix microfin tube configurations have been examined in both

D. A. Yashar; M. J. Wilson; H. R. Kopke; D. M. Graham; J. C. Chato; T. A. Newell

2001-01-01

248

Laser cooling of semiconductor quantum wells: Theoretical framework and strategy for deep optical refrigeration by luminescence upconversion  

SciTech Connect

Optical refrigeration has great potential as a viable solution to thermal management for semiconductor devices and microsystems. We have developed a first-principles-based theory that describes the evolution of thermodynamics - i.e., thermokinetics - of a semiconductor quantum well under laser pumping. This thermokinetic theory partitions a well into three subsystems: interacting electron-hole pairs (carriers) within the well, the lattice (thermal phonons), and the ambient (a thermal reservoir). We start from the Boltzmann kinetic equations and derive the equations of motion for carrier density and temperature, and lattice temperature, under the adiabatic approximation. A simplification is possible as a result of ultrafast energy exchange between the carriers and phonons in semiconductors: a single-temperature equation is sufficient for them, whereas the lattice cooling is ultimately driven by the much slower radiative recombination (upconverted luminescence) process. Our theory microscopically incorporates photogeneration and radiative recombination of the interacting electron-hole pairs. We verify that Kubo-Martin-Schwinger relation holds for our treatment, as a necessary condition for consistency in treatment. The current theory supports steady-state solutions and allows studies of cooling strategies and thermodynamics. We show by numerical investigation of an exemplary GaAs quantum well that higher power cools better when the laser is detuned from the band edge between a critical negative value and the ambient thermal energy. We argue for the existence of such a counterintuitive lower bound. Most importantly, we show that there exists an actual detuning, 3 meV above the band edge in the simulated free-carrier case and expected to be pinned at the excitonlike absorption peak owing to Coulomb many-body effects, for optimal laser cooling. Significant improvement in cooling efficacy and theoretical possibility of deep refrigeration are verified with such a fixed optimal actual detuning. In essence, this work provides a consistent microscopic framework and an optimization strategy for achieving net deep cooling of semiconductor quantum wells and related microsystems.

Li Jianzhong [NanoScience Solutions, Inc., Cupertino, California 95014 (United States)

2007-04-15

249

Generalized Pressure Drop Correlation for Evaporation and Condensation of Alternative Refrigerants in Smooth and Micro-Fin Tubes.  

National Technical Information Service (NTIS)

This paper presents a pressure drop correlation for evaporation and condensation in smooth and micro-fin tubes. The correlation was developed from a database consisting of the following pure and mixed refrigerants: R125, R134a, R32, R410A (R32/R125 50/50 ...

H. Y. Choi M. A. Kedzierski P. A. Domanski

1999-01-01

250

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

251

Comparison of frictional pressure drop models during annular flow condensation of R600a in a horizontal tube at low mass flux and of R134a in a vertical tube at high mass flux  

Microsoft Academic Search

This study compares well-known two-phase pressure drop models with the experimental results of a condensation pressure drop of (i) R600a in a 1m long horizontal smooth copper tube with an inner diameter of 4mm, outer diameter of 6mm and (ii) R134a in a 0.5m vertical smooth copper tube with an inner diameter of 8.1mm and outer diameter of 9.52mm. Different

A. S. Dalkilic; O. Agra; I. Teke; S. Wongwises

2010-01-01

252

Vapour–liquid equilibrium data for the 1,1,1,2 tetrafluoroethane (R134a) + dimethyl ether (DME) system at temperatures from 293.18 to 358.15 K and pressures up to about 3 MPa  

Microsoft Academic Search

Isothermal vapour–liquid equilibrium data have been measured for the binary system R134a+DME at five temperatures between 293.18 and 358.15K, and pressures between 0.4899 and 2.9442MPa. The peculiarity of this system is the existence of an azeotrope with a minimum pressure, which disappears at 358.15K. The experimental method used in this work is of the static-analytic type, taking advantage of two

Alain Valtz; Leila Gicquel; Christophe Coquelet; Dominique Richon

2005-01-01

253

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

254

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

255

Adsorbent Evaluation and Adsorption Equilibrium Data for R-123, R-134a, and Toluene on Selected Activated Carbons, Silica Gels, and Polymeric Resins.  

National Technical Information Service (NTIS)

Adsorption equilibria data have been measured for refrigerant R-123 vapor on Rohm and Haas Ambersorb 563; Calgon; Carbon BPL activated carbon and CAL liquid phase carbon; Kansai Coke and Chemical Company Maxsorb G505Z30; Norit RD2030; Adcoa silica gel, 40...

D. T. Croft S. M. Maurer

1997-01-01

256

Superfluid Stirling refrigerator: A new method for cooling below 1 Kelvin  

NASA Astrophysics Data System (ADS)

We have invented and built a new type of cryocooler, which we call the superfluid Stirling refrigerator (SSR). The first prototype reached 0.6 K from a starting temperature of 1.2 K. The working fluid of the SSR is the (sup 3)He solute in a superfluid He(3) - He(4) solution. At low temperatures, the superfluid He(4) is in its quantum ground state, and therefore is thermodynamically inert, while the He(3) solute has the thermodynamic properties of a dense ideal gas. Thus, in principle, any refrigeration cycle that can use an ideal gas can also use the He(3) solute as working fluid. In our SSR prototype, bellows-sealed superleak pistons driven by a room-temperature camshaft work on the He(3) solute. Ultimately, we anticipate elimination of moving parts by analogy with pulse-tube refrigeration.

Kotsubo, V.; Swift, G. W.

257

Use of a Joule-Thomson micro-refrigerator to cool a radio-frequency coil for magnetic resonance microscopy  

NASA Astrophysics Data System (ADS)

A method is described for cryogenically cooling a rf detector coil, as used in high-resolution magnetic resonance imaging (MRI), to enhance image signal-to-noise ratio (SNR). By incorporating the rf coil into a Joule-Thomson micro-refrigerator, the coil is precision-cooled to 70 K using only a source of high-pressure nitrogen gas at room temperature, avoiding the need for liquid cryogens. The rf coil is insulated by a glass vacuum dewar that permits its use in proximity to biological tissues. Design and operation of the cryogenic system are described and its performance is demonstrated in a 1.5 T clinical MRI scanner with images of a water phantom and a sheep intervertebral disc specimen. SNR gains of two to three times were obtained, compared to a similar coil at room temperature. The potential of this technology for local high-resolution MRI is discussed.

Wright, A. C.; Song, H. K.; Elliott, D. M.; Wehrli, F. W.

2005-01-01

258

Method and apparatus for using solar energy to augment a refrigerant heating and cooling system  

SciTech Connect

An uninsulated tank-type solar collector for a reverse refrigeration-cycle heating system is mounted in ambient air and contains a mass of water and/or ice having a refrigerant expansion coil immersed therein. At least one of the walls of the tank contacts ambient air on one surface, and the mass of water and/or ice on the other surface. Thus, the mass of water and/or ice exchanges or transfers heat from the ambient air by conduction to the expansion coil. During transition from water to ice, the freezing water liberates large amounts of energy as ''heat of fusion'' which is absorbed by the expansion coil.

Jones, R.D.

1982-09-28

259

Magnetic-Wheel Refrigerator: Magnetocaloric machine offers high efficiency and a wide range of cooling temperatures.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A magnetic-wheel refrigerator has been proposed which operates at high efficiency over temperature-reduction ranges from 2 to 300K. In contrast, previous magnetic re...

1984-01-01

260

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

261

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

262

Pressure drop during condensation of refrigerants in pipe minichannels  

NASA Astrophysics Data System (ADS)

The present paper describes results of experimental investigations of pressure drop during the condensation of R134a, R404a and R407C refrigerants in pipe minichannels with internal diameter 0.31-3.30 mm. The results concern investigations of the mean and local pressure drop in single minichannels. The results of experimental investigations were compared with the calculations according to the correlations proposed by other authors. A pressure drop during the condensation of refrigerants is described in a satisfactory manner with Friedel and Garimella correlations. On the basis of the experimental investigations, the authors proposed their own correlation for calculation of local pressure drop during condensation in single minichannels.

Bohdal, Tadeusz; Charun, Henryk; Sikora, Ma?gorzata

2012-08-01

263

Investigation of the Influence of Cooling Water Inlet Temperature on Characteristics and Ammonia Charging Quantity of Ammonia-Water Absorption Refrigerator  

NASA Astrophysics Data System (ADS)

For purposes such as freezing and ice accumulation which require temperatures below 0 degrees, ammonia-water absorption refrigerator is being looked at once again. If used for these purpose, it is usually driven all through the year. In this case, cooling water inlet temperature which greatly influences absorption cycle changes very widely. So in such conditions, it is hoped to be driven high efficiently. And ammonia's charging quantity is required as small as possible on account of poisonous. But when it driven all through the year, ammonia charging quantity influences the efficiency greatly. So this research aims to clarify the ammonia charging quantity with which ammonia-water absorption refrigerator can be driven high efficiently. So static simulation model was made. By using this tool, we investigated the influence of cooling water inlet temperature on COP, solution concentration. As a result, minimum ammonia charging quantity with which ammonia water absorption refrigerator can be driven was obtained.

Takei, Toshitaka; Saito, Kiyoshi; Kawai, Sunao

264

A new type of cryopump with a metal cryopanel cooled below 3.6 K by a two-stage GM refrigerator  

Microsoft Academic Search

A new type of cryopump with a 3.6 K metal cryopanel cooled by a two-stage Gifford-McMahon (GM) refrigerator using a new regenerator material of erbium 3 nickel (Er3Ni) has been developed. This cryopump has no Joule-Thomson (JT) expansion valves and requires no liquefied gases such as helium and nitrogen. The new point of this cryopump is that although the cooling

Y Iwasa; S Ito

1996-01-01

265

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

266

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

267

PVT Measurements on tetrafluoroethane (R134a) along the vapor-liquid equilibrium boundary between 288 and 373 K and in the liquid state from the triple point to 265 K  

NASA Astrophysics Data System (ADS)

For the investigations of the gas-liquid phase equilibria, a new apparatus has been developed capable of simultaneously determining the pressure and the liquid and vapor densities using Archimedes' principle. The relative measurement uncertainties of the liquid and vapor densities of R134a (purity, 99.999%) at 313 K are 2×10-4 and 7×10-4, respectively (95% confidence level). For the measurements in the liquid region along nine quasi-isochores at pressures up to 5 MPa, an isochoric apparatus was used. The relative measurement uncertainty of pv/(RT) is less than 1×10-3. In addition to the investigation of the ( p, v, T) properties, the temperature and pressure at the triple point and the vapor pressure between the triple point and 265 K were measured. On the basis of these data, a vapor pressure correlation has been developed that reproduces the measured vapor pressures within the uncertainty of measurement. The results of our measurements are compared with a fundamental equation for R134a, which is based on the measurements of other research groups.

Blanke, W.; Klingenberg, G.; Weiss, R.

1995-09-01

268

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

269

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

270

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

271

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

272

Boiling heat transfer enhancement with carbon nanotubes for refrigerants used in building air-conditioning  

Microsoft Academic Search

In this study, the effect of carbon nanotubes (CNTs) on nucleate boiling heat transfer is investigated. Two halocarbon refrigerants of R123 and R134a for building chillers were used as working fluids and 1.0vol.% of CNTs was added to them to examine the heat transfer enhancement with CNTs. The experimental apparatus was composed of a stainless steel vessel and a 152.0mm

Ki-Jung Park; Dongsoo Jung

2007-01-01

273

Experimental Study on Condensation of Pure Refrigerants in Horizontal Micro-fin Tubes  

NASA Astrophysics Data System (ADS)

This paper presents the heat transfer and pressure drop correlations for condensation in micro-fin tubes. Experimental data for eleven micro-fin tubes with different fin dimensions were used, and the refrigerants tested were R22, R123 and R134a. The predicted results using new correlations show good agreement with experimental results within an absolute deviation of ±30%. Experimental results for the micro-fin tubes were also compared with previous correlations for micro-fin Tubes.

Yonemoto, Ryuichiro; Koyama, Shigeru

274

Prediction of two-phase pressure gradients of refrigerants in horizontal tubes  

Microsoft Academic Search

Two-phase pressure drop data were obtained for evaporation in two horizontal test sections of 10.92 and 12.00 mm diameter for five refrigerants (R-134a, R-123, R-402A, R-404A and R-502) over mass velocities from 100 to 500 kg\\/m2 s and vapor qualities from 0.04 to 1.0. These data have then been compared against seven two-phase frictional pressure drop prediction methods. Overall, the

M. B. Ould Didi; N. Kattan; J. R. Thome

2002-01-01

275

Critical heat flux in multi-microchannel copper elements with low pressure refrigerants  

Microsoft Academic Search

New saturated critical heat flux (CHF) data have been obtained experimentally in two different multi-microchannel heat sinks made in copper with three low pressure refrigerants (R134a, R236fa, R245fa). One of the test sections has 20 parallel rectangular channels, 467?m wide and 4052?m deep while the second has 29 channels, 199?m wide and 756?m deep. The microchannels are 30mm long in

Jung Eung Park; John Richard Thome

2010-01-01

276

A progress report on using bolometers cooled by adiabatic demagnetization refrigeration  

NASA Technical Reports Server (NTRS)

For sensitive detection of astronomical continuum radiation in the 200 micron to 3 mm wavelength range, bolometers are presently the detectors of choice. In order to approach the limits imposed by photon noise in a cryogenically cooled telescope in space, bolometers must be operated at temperatures near 0.1 K. Researchers report progress in building and using bolometers that operate at these temperatures. The most sensitive bolometer had an estimated noise equivalent power (NEP) of 7 x 10(exp 017) W Hz(exp -1/2). Researchers also briefly discuss the durability of paramagnetic salts used to cool the bolometers.

Lesyna, L.; Roellig, T.; Savage, M.; Werner, Michael W.

1989-01-01

277

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

278

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

279

Evaporative heat transfer and enhancement performance of serpentine tubes with strip-type inserts using refrigerant-134a  

SciTech Connect

Recent technological implications have given rise to increased interest in enhancement of the in-tube evaporation used in many air conditioning and refrigeration systems. Although many past studies have examined in-tube evaporative heat transfer enhancement and the associated pressure drop with internally finned tubes, in-tube evaporations with strip-type inserts, using R-134a as a refrigerant, have not been conducted. In addition, the fundamental phenomenon of nucleate boiling from a heated wall subject to a strip-type insert is as yet not well understood, especially for the flow in serpentine tubes. In this study, flow boiling tests were conducted in serpentine coil with inserts. To accomplish these tasks, experiments were performed in a seven-pass serpentine test tube with longitudinal strip and cross-strip types inserts, 10.6-mm inside diameter with R-134a as the boiling fluid immersed in a hot water bath.

Hsieh, S.S.; Jang, K.J.; Huang, M.T. [National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China). Dept. of Mechanical Engineering

1999-08-01

280

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

281

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

282

Measurements of viscosity of refrigerants in the vapor phase  

SciTech Connect

Measurements of the viscosity of refrigerants R124, R125, R134a, and R152a in the vapor phase are presented. The measurements, performed in a new vibrating-wire instrument, cover a temperature range from 273 to 333 K from about atmospheric pressure up to below the saturation pressure. The uncertainty of the reported values is estimated to be better than {+-}1%. Comparison with measurements of other investigators reveals a lack of reliable data in the vapor region for these compounds.

Assael, M.J.; Polimatidou, S.K. [Aristotle Univ., Thessaloniki (Greece). Faculty of Chemical Engineering

1997-03-01

283

Two-phase pressure drop of refrigerants during flow boiling in small channels: an experimental investigation and correlation development  

Microsoft Academic Search

Two-phase flow pressure drop measurements were made during a phase-change heat transfer process with three refrigerants (R-134a, R-12, and R-113) at six different pressures ranging from 138 to 856 kPa, and in two sizes of round tubes (2.46 and 2.92 mm inside diameters) and one rectangular channel (4.06 × 1.7 mm). The data were compared with those from large tubes

T. N Tran; M.-C Chyu; M. W Wambsganss; D. M France

2000-01-01

284

Vapor-liquid coexistence curves in the critical region and the critical temperatures and densities of 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), and 1,1,1,2,3,3-hexafluoropropane (R-236ea)  

Microsoft Academic Search

The vapor-liquid coexistence curves in the critical region of 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), and 1,1,1,2,3,3-hexafluoropropane (R-236ea) were measured by a visual observation of the meniscus disappearance in an optical cell. Seventeen saturated-vapor and -liquid densities have been measured for R-134a. Thirty-five saturated-vapor and -liquid densities have been measured for R-143a. Twenty-seven saturated-vapor and -liquid densities have been measured for R-236ea.

Hirokazu Aoyama; Go Kishizawa; Haruki Sato; Koichi Watanabe

1996-01-01

285

Transcritical carbon dioxide small commercial cooling applications analysis  

Microsoft Academic Search

This paper presents a project to develop an R744 commercial single door bottle cooler that is cost competitive and matches the performance of typical cost optimised R404A and R134a systems. Compressors with different displacement and efficiency values are evaluated for refrigerating systems with fin and tube and steel wire-on-tube gas coolers. Capillary tubes are tested. A methodology to properly sizing

Luca Cecchinato; Marco Corradi

2011-01-01

286

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

287

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

288

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

289

PVT measurements on tetrafluoroethane (R134a) along the vapor-liquid equilibrium boundary between 288 and 373 K and in the liquid state from the triple point to 265 K  

SciTech Connect

For the investigations of the gas-liquid phase equilibria, a new apparatus has been developed capable of simultaneously determining the pressure and the liquid and vapor densities using Archmiedes` principle. The relative measurement uncertainties of the liquid and vapor densities of R134a (purity, 99.999%) at 313 K are 2 X 10 {sup -4} and 7 X 10{sup -4}, respectively (95% confidence level). For the measurements in the liquid region along nine quasi-isochores at pressures up to 5MPa, an isochoric apparatus was used. The relative measurement uncertainty of pv/(RT) is less than 1X10{sup -3}. In addition to the investigation of the (p,v,T) properties, the temperature and pressure at the triple point and the vapor pressure between the triple point and 265 K were measured. On the basis of these data, a vapor pressure correlation has been developed that reproduces the measured vapor pressures within the uncertainty of measurement. The results of our measurements of other research groups.

Blanke, W.; Klingenberg, G.; Weiss, R. [Physikalisch-Technische Bundesantalt, Braunschweig (Germany)

1995-09-01

290

Waste heat driven absorption\\/vapor-compression cascade refrigeration system for megawatt scale, high-flux, low-temperature cooling  

Microsoft Academic Search

A novel cascaded absorption\\/vapor-compression cycle with a high temperature lift for a naval ship application was conceptualized and analyzed. A single-effect LiBr–H2O absorption cycle and a subcritical CO2 vapor-compression cycle were coupled together to provide low-temperature refrigerant (?40°C) for high heat flux electronics applications, medium-temperature refrigerant (5°C) for space conditioning and other low heat flux applications, and as an auxiliary

Srinivas Garimella; Ashlie M. Brown; Ananda Krishna Nagavarapu

2011-01-01

291

Support of NASA ADR/ Cross-Enterprise NRA Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling from 10K to 50mK, Development of a Heat Switch  

NASA Technical Reports Server (NTRS)

Mechanical heat switches are used in conjunction with sorption refrigerators, adiabatic demagnetization refrigerators and for other cryogenic tasks including the pre-cooling cryogenic systems. They use a mechanical actuator which closes Au plated Cu jaws on an Au plated Cu bar. The thermal conductance in the closed position is essentially independent of the area of the jaws and proportional to the force applied. It varies linearly with T. It is approximately 10mW/K for 200 N at 1.5K. In some applications, the heat switch can be driven from outside the cryostat by a rotating rod and a screw. Such heat switches are available commercially from several sources. In other applications, including systems for space, it is desirable to drive the switch using a cold linear motor, or solenoid. Superconducting windings are used at temperatures s 4.2K to minimize power dissipation, but are not appropriate for pre-cooling a system at higher temperatures. This project was intended to improve the design of solenoid activated mechanical heat switches and to provide such switches as required to support the development of Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling from 10 K to 50 mK at GSFC. By the time funding began in 5/1/01, the immediate need for mechanical heat switches at GSFC had subsided but, at the same time, the opportunity had arisen to improve the design of mechanical heat switching by incorporating a "latching solenoid". In this device, the solenoid current is required only for changing the state of the switch and not during the whole time that the switch is closed.

Richards, Paul L.

2005-01-01

292

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

293

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

294

Large area impingement spray cooling from multiple normal and inclined spray nozzles  

NASA Astrophysics Data System (ADS)

An inclined spray chamber with four multiple nozzles to cool a 1 kW 6U electronic test card has been designed and tested in this study. The multiple inclined sprays can cover the same heated surface area as that with the multiple normal sprays but halve the volume of the spray chamber. The spray cooling system used R134a as a working fluid in a modified refrigeration cycle. It is observed that increasing mass flow rate and pressure drop across the nozzles improved the heat transfer coefficient with a maximum enhancement of 117 %, and reduced the maximum temperature difference at the heated surface from 13.8 to 8.4 °C in the inclined spray chamber with a heat flux of 5.25 W/cm2, while the heat transfer coefficient of the normal spray increased with a maximum enhancement of 215 % and the maximum temperature difference decreased from 10.8 to 5.4 °C under similar operating conditions. We conclude that the multiple inclined sprays could produce a higher heat transfer coefficient but with an increase in non-uniformity of the surface temperature compared with the multiple normal sprays.

Yan, Z. B.; Duan, F.; Wong, T. N.; Toh, K. C.; Choo, K. F.; Chan, P. K.; Chua, Y. S.; Lee, L. W.

2013-07-01

295

Airborne Exposure to Trihalomethanes from Tap Water in Homes with Refrigeration-Type and Evaporative Cooling Systems  

Microsoft Academic Search

This study evaluates airborne concentrations of common trihalomethane compounds (THM) in selected living spaces of homes supplied with chlorinated tap water containing >85 ppb total THM. Three small homes in an arid urban area were selected, each having three bedrooms, a full bath, and approximately 1000 square feet; two homes had standard (refrigeration-type) central air conditioning and the third had

Brent D. Kerger; David R. Suder; Chuck E. Schmidt; Dennis J. Paustenbach

2005-01-01

296

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

297

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

298

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

299

Toxicity Data to Determine Refrigerant Concentration Limits  

SciTech Connect

This report reviews toxicity data, identifies sources for them, and presents resulting exposure limits for refrigerants for consideration by qualified parties in developing safety guides, standards, codes, and regulations. It outlines a method to calculate an acute toxicity exposure limit (ATEL) and from it a recommended refrigerant concentration limit (RCL) for emergency exposures. The report focuses on acute toxicity with particular attention to lethality, cardiac sensitization, anesthetic and central nervous system effects, and other escape-impairing effects. It addresses R-11, R-12, R-22, R-23, R-113, R-114, R-116, R-123, R-124, R-125, R-134, R-134a, R-E134, R-141b, R-142b, R-143a, R-152a, R-218, R-227ea, R-236fa, R-245ca, R-245fa, R-290, R-500, R-502, R-600a, R-717, and R-744. It summarizes additional data for R-14, R-115, R-170 (ethane), R-C318, R-600 (n-butane), and R-1270 (propylene) to enable calculation of limits for blends incorporating them. The report summarizes the data a nd related safety information, including classifications and flammability data. It also presents a series of tables with proposed ATEL and RCL concentrations-in dimensionless form and the latter also in both metric (SI) and inch-pound (IP) units of measure-for both the cited refrigerants and 66 zerotropic and azeotropic blends. They include common refrigerants, such as R-404A, R-407C, R-410A, and R-507A, as well as others in commercial or developmental status. Appendices provide profiles for the cited single-compound refrigerants and for R-500 and R-502 as well as narrative toxicity summaries for common refrigerants. The report includes an extensive set of references.

Calm, James M.

2000-09-30

300

Magnetic refrigeration: materials, design, and applications. January 1975-April 1989 (Citations from the INSPEC: Information Services for the Physics and Engineering Communities data base). Report for January 1975-April 1989  

SciTech Connect

This bibliography contains citations concerning cryogenics using magnetic refrigerants. Refrigerant properties, magnetic materials, and thermal characteristics are discussed. Magnetic refrigerators are used for helium liquefaction, cooling superconductors, and superfluid helium production. Carnot-cycle refrigerators, reciprocating refrigerators, parisitic refrigerators, Ericsson refrigerators, and Stirling-cycle refrigerators are among the types of magnetic refrigerators evaluated. (Contains 103 citations fully indexed and including a title list.)

Not Available

1989-05-01

301

Measurement of the cooling capacity of an RMC-Cryosystems Model LTS 4.5-025 closed-cycle helium refrigerator  

NASA Astrophysics Data System (ADS)

The cooling capacity of a recently purchased RMC-Cryosystems Model LTS 4.5-025 closed-cycle He refrigerator was measured over the range 4-35 K. It is found that the nominal cooling capacity of 250 mW is only met or exceeded over a narrow temperature range around 4.3 + or - 0.5 K, and that, above this range, there exists a considerable region of much lower cooling capacity, not exceeding about 100 mW. It is believed that this behavior results from use of a fixed-aperture Joule-Thompson expansion valve, and might be alleviated if the J-T valve could be adjusted to compensate for changing flow within the 5-20 K temperature range. Present performance may severely limit or prevent effective use in applications where an irreducible heat inflow exists which is greater than about 100 mW, yet substantially less than the quoted capacity at about 4 K.

de Zafra, R. L.; Mallison, W. H.; Emmons, L. K.; Koller, D.

1991-05-01

302

Measurement of the cooling capacity of an RMC-Cryosystems Model LTS 4.5-025 closed-cycle helium refrigerator  

NASA Technical Reports Server (NTRS)

The cooling capacity of a recently purchased RMC-Cryosystems Model LTS 4.5-025 closed-cycle He refrigerator was measured over the range 4-35 K. It is found that the nominal cooling capacity of 250 mW is only met or exceeded over a narrow temperature range around 4.3 + or - 0.5 K, and that, above this range, there exists a considerable region of much lower cooling capacity, not exceeding about 100 mW. It is believed that this behavior results from use of a fixed-aperture Joule-Thompson expansion valve, and might be alleviated if the J-T valve could be adjusted to compensate for changing flow within the 5-20 K temperature range. Present performance may severely limit or prevent effective use in applications where an irreducible heat inflow exists which is greater than about 100 mW, yet substantially less than the quoted capacity at about 4 K.

De Zafra, R. L.; Mallison, W. H.; Emmons, L. K.; Koller, D.

1991-01-01

303

Vapor-liquid coexistence curves in the critical region and the critical temperatures and densities of 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), and 1,1,1,2,3,3-hexafluoropropane (R-236ea)  

SciTech Connect

The vapor-liquid coexistence curves in the critical region of 1,1,1,2-tetrafluoroethane (R-134a), 1,1,1-trifluoroethane (R-143a), and 1,1,1,2,3,3-hexafluoropropane (R-236ea) were measured by a visual observation of the meniscus disappearance in an optical cell. Seventeen saturated-vapor and -liquid densities have been measured for R-134a. Thirty-five saturated-vapor and -liquid densities have been measured for R-143a. Twenty-seven saturated-vapor and -liquid densities have been measured for R-236ea. The level and location of the meniscus, as well as the intensity of the critical opalescence were considered in the determination of the critical temperature and density for each fluid. R-134a was found to have (374.083 {+-} 0.010) K and (509 {+-} 1) kg/m{sup 3}, R-143a, (345.860 {+-} 0.010) K and (434 {+-} 1) kg/m{sup 3}, and R-236ea, (412.375 {+-} 0.015) K and (568 {+-} 1) kg/m{sup 3}.

Aoyama, H.; Kishizawa, G.; Sato, H.; Watanabe, K. [Keio Univ., Hiyoshi, Yokohama (Japan)] [Keio Univ., Hiyoshi, Yokohama (Japan)

1996-09-01

304

Determination of Properties of Zeolite/Refrigerant Combinations for Solar Refrigeration Systems. Final Report.  

National Technical Information Service (NTIS)

The determination of properties of zeolite/refrigerant combinations of solar refrigeration systems are reviewed in this final report. The US DOE has funded several studies aimed at identifying potential rerigerant/absorption pairs for solar cooling applic...

1985-01-01

305

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

306

Measurements of the thermal conductivity of refrigerants in the vapor phase  

SciTech Connect

Measurements of the thermal conductivity of refrigerants R124, R125, and R134a in the vapor phase are presented. The measurements, performed in a newly developed transient hot-wire instrument, cover a temperature range from 273 to 333 K, and a pressure range from about atmospheric up to below the saturation pressure. A finite-elements program developed allowed the reexamination of the major corrections employed in the analysis of the results. The uncertainty of the reported values is estimated to be better than {+-}1%. Comparisons with measurements of other investigators along the saturation line show a lack of reliable thermal conductivity data in the vapor phase for these compounds.

Assael, M.J.; Malamataris, N.; Karagiannidis, L. [Aristotle Univ., Thessaloniki (Greece). Faculty of Chemical Engineering

1997-03-01

307

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

308

Ideal orifice pulse tube refrigerator performance  

NASA Technical Reports Server (NTRS)

The recent development of orifice pulse tube refrigerators has raised questions as to what limits their ultimate performance. Using an analogy to the Stirling cycle refrigerator, the efficiency (cooling power per unit input power) of an ideal orifice pulse tube refrigerator is shown to be T1/T0, the ratio of the cold temperature to the hot temperature.

Kittel, P.

1992-01-01

309

Refrigeration System which Compensates for Heat Leakage.  

National Technical Information Service (NTIS)

A refrigeration system/cycle includes two or more refrigeration stages, in which one or more of the warmer stages provide(s) cooling to partially compensate for heat leakage that would otherwise leak to the colder stage(s). The refrigeration system includ...

D. S. Beck

2004-01-01

310

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

311

The high-capacity, spaceborne, Vuilleumier refrigerator  

NASA Astrophysics Data System (ADS)

This paper describes the features and gives the thermal performance capabilities of the high-capacity (Hi Cap), Vuilleumier cryogenic refrigerator. This refrigerator simultaneously cools at three different temperature levels, the lowest being below 15 K. It is designed to cool electro-optical sensors in a spaceborne environment. The basic design of the Hi Cap refrigerator is discussed, and the individual machine elements are identified. Data on the thermal performance of this refrigerator is presented for various thermal load conditions on the three cold stages. The capability of this refrigerator for off-design-speed operation is also discussed.

Doody, R. D.

1980-01-01

312

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

313

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

314

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

315

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

316

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

317

An irreversible thermodynamic model for 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 coefficient of performance (COP) and maximum cooling load. A new model is presented to describe an irreversible absorption refrigerator, in which not only the irreversibilities of heat conduction but also those resulting from friction, eddy and other irreversible

R. Fathi; C. Guemimi; S. Ouaskit

2004-01-01

318

Modeling of secondary loop refrigeration systems in supermarket applications  

Microsoft Academic Search

Today's supermarket refrigeration systems predominantly use the direct expansion vapor compression cycle to provide cooling to refrigeration and freezer display cases. Next to the environmental concerns of global warming and ozone depletion associated with leakage of the currently used CFC and HCFC refrigerants from these systems, there is also a concern for the rising cost of purchasing suitable alternative refrigerants

William Travis Horton

2002-01-01

319

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

320

A New Surface Tension Equation for Refrigerants  

NASA Astrophysics Data System (ADS)

This study presents a new formula for the surface tension prediction of refrigerants. As a first step, an analysis of the available experimental surface tension data for refrigerants was performed. The experimental data were collected, after a careful literature survey, for the following pure fluids: R11, R12, R13, R13B1, R14, R21, R22, R23, R32, R113, R114, R115, R123, R124, R125, R134, R134a, R141b, R143a, R152a, R218, R227ea, R236ea, R236fa, R245ca, R245fa, R365mfc, and R1234yf. Then, the experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding-states theory existing in the literature. As a final step, to minimize the deviation between the predicted data and the experimental data and to find the optimal equation for experimental data regression, a (? + ?)-evolution strategy was adopted. After a careful statistical analysis of the results, a new formula based on the corresponding-states principle with improved representation of the experimental results was found and proposed.

Di Nicola, Giovanni; Di Nicola, Cristiano; Moglie, Matteo

2013-12-01

321

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

322

Micro and NanoTechnology: A Critical Design Key in Advanced Thermoelectric Cooling Systems  

Microsoft Academic Search

Advanced thermoelectric (TE) cooling technologies are now receiving more research attention, to provide cooling in advanced\\u000a vehicles and residential systems to assist in increasing overall system energy efficiency and reduce the impact of greenhouse\\u000a gases from leakage by current R-134a systems. This work explores the systems-related impacts, barriers, and challenges of\\u000a using micro-technology solutions integrated with advances in nano-scale thermoelectric

Terry J. Hendricks; Naveen K. Karri

2009-01-01

323

Surface tension for 1,1,1-trifluorethane (R-143a), 1,1,1,2-tetrafluoroethane (R-134a), 1,1-dichloro-2,2,3,3,3-pentafluoropropane (R-225ca), and 1,3-dichloro-1,2,2,3,3-pentafluoropropane (R-225cb)  

SciTech Connect

The surface tensions for 1,1,1-trifluoroethane (R-143a), 1,1,1,2-tetrafluoroethane (R-134a), 1,1-dichloro-2,2,3,3,3-pentafluoropropane (R-225ca), and 1,3-dichloro-1,2,2,3,3-pentafluoropropane (R-225cb) have been measured by the differential capillary rise method. The results were obtained in the temperature range between 273 K and 343 K. The experimental uncertainties of temperature and surface tension are estimated to be within {+-}20 mK and {+-}0.15 mN/m, respectively. A correlation for the surface tension as a function of temperature is presented.

Higashi, Yukihiro; Shibata, Takahide [Iwaki Meisei Univ., Fukushima (Japan). Dept. of Mechanical Engineering] [Iwaki Meisei Univ., Fukushima (Japan). Dept. of Mechanical Engineering; Okada, Masaaki [Tsukuba Coll. of Technology, Ibaraki (Japan). Dept. of Mechanical Engineering] [Tsukuba Coll. of Technology, Ibaraki (Japan). Dept. of Mechanical Engineering

1997-05-01

324

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

325

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

326

Heat transfer during condensation of refrigerants in tubular minichannels  

NASA Astrophysics Data System (ADS)

The present paper describes the results of experimental investigations of heat transfer during condensation of R134a, R404A and R407C in pipe minichannels with internal diameters 0.31-3.30 mm. The results concern investigations of the local heat transfer coefficient. The results were compared with the correlations proposed by other authors. Within the range of examined parameters of the condensation process in minichannels made of stainless steel, it was established that the values of the heat transfer coefficient may be described with Akers et al., Mikielewicz and Shah correlations within a limited range of the mass flux density of the refrigerant and the minichannel diameter. On the basis of experimental investigations, the authors proposed their own correlation for the calculation of local heat transfer coefficient.

Bohdal, Tadeusz; Charun, Henryk; Sikora, Ma?gorzata

2012-10-01

327

Thermal design and verification of an instrument cooling system for infrared detectors utilizing the Oxford Stirling cycle refrigerator  

NASA Technical Reports Server (NTRS)

A detailed nodal computer model was developed to thermally represent the hardware, and sensitivity studies were performed to evaluate design parameters and orbital environmental effects of an instrument cooling system for IR detectors. Thermal-vacuum testing showed excellent performance of the system and a correspondence with math model predictions to within 3 K. Results show cold stage temperature sensitivity to cold patch backload, outer stage external surface emittance degradation, and cold stage emittance degradation, respectively. The increase in backload on the cold patch over the mission lifetime is anticipated to be less than 3.0 watts, which translates to less than a 3-degree increase in detector temperatures.

Werrett, Stephen; Seivold, Alfred L.

1990-01-01

328

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

329

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

330

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

331

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

332

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

333

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

334

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

335

Magnetic refrigeration: Materials, design, and applications. (Latest citations from the INSPEC: Information Services for the Physics and Engineering Communities datab base). Published Search  

SciTech Connect

The bibliography contains citations concerning cryogenics using magnetic refrigerants. Refrigerant properties, magnetic materials, and thermal characteristics are discussed. Magnetic refrigerators are used for helium liquefaction, cooling superconductors, and superfluid helium production. Carnot-cycle refrigerators, reciprocating refrigerators, parasitic refrigerators, Ericsson refrigerators, and Stirling cycle refrigerators are among the types of magnetic refrigerators evaluated. (Contains a minimum of 87 citations and includes a subject term index and title list.)

Not Available

1992-10-01

336

Viscosity of saturated liquid fluorocarbon refrigerants from 273 to 353 K  

NASA Astrophysics Data System (ADS)

Viscosity measurements were carried out on saturated liquid fluorocarbon refrigerants using an improved capillary viscometer for 11 kinds of fluorocarbon refrigerants; CCl3F (R11), CCl2F2 (R12), CHClF2 (R22), CBrF3 (R13B1), CH3CHF2 (R152a), CCl2FCClF2 (R113), CHCl2CF3 (R123), CHClFCClF2 (R123a), CH3CF3 (R143a), CClF2CCl2F2 (R114), and CH2FCF3 (R134a), in the temperature range from 273 to 353 K. An equation is given to represent the viscosity as a function of temperature.

Kumagai, A.; Takahashi, S.

1991-01-01

337

Current Information on the Properties of Hydrofluorocarbons(HFCs) and Other Pure Refrigerants  

NASA Astrophysics Data System (ADS)

In 1994, the JSRAE published 'HFCs and HCFCs', JAR Thermodynamic Tables, Vol.1, Version 1.0, providing the thermodynamic properties of 12 refrigerants with the software. At the time, experimental data for new alternative refrigerants were qualitatively and quantitatively limited. Many reliable experimental and theoretical information have been accumulated till present for pure HFCs. The ideal gas heat capacity values with an uncertainty of ±0.2 % and the transport properties are the good examples. New international standards on the molar gas constant or molar masses were defined very recently. As a review paper on the properties of HFCs, simple equations of the ideal-gas heat capacity, vapor pressures, saturated-liquid density, virial coefficients, surface tension, viscosity, thermal conductivity, and the information on the material compatibility and solubility with lubricants are summarized mainly for R32, R125, R134a, R143a, and R152a.

Sato, Haruki; Takaishi, Yoshinori; Kagawa, Noboru; Yokoyama, Chiaki; Higashi, Yukihiro; Fujii, Kenichi; Murakami, Kazuhiko; Assael, Marc J.; Noguchi, Masahiro; Tanabe, Hirone; Fukushima, Masato; Takigawa, Katsuya

338

Prediction of refrigerant void fraction in horizontal tubes using probabilistic flow regime maps  

SciTech Connect

A state of the art review of two-phase void fraction models in smooth horizontal tubes is provided and a probabilistic two-phase flow regime map void fraction model is developed for refrigerants under condensation, adiabatic, and evaporation conditions in smooth, horizontal tubes. Time fraction information from a generalized probabilistic two-phase flow map is used to provide a physically based weighting of void fraction models for different flow regimes. The present model and void fraction models in the literature are compared to data from multiple sources including R11, R12, R134a, R22, R410A refrigerants, 4.26-9.58 mm diameter tubes, mass fluxes from 70 to 900 kg/m{sup 2} s, and a full quality range. The present model has a mean absolute deviation of 3.5% when compared to the collected database. (author)

Jassim, E.W.; Newell, T.A.; Chato, J.C. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States)

2008-04-15

339

Fast, Low-Duty-Cycle Sorption Refrigerators  

NASA Technical Reports Server (NTRS)

Metal hydride/hydrogen-sorption refrigerators developed to provide rapid, intermittent cooling at temperatures between 30 and 10 K. In original application, refrigerators cool infrared detectors aboard spacecraft, exhausting heat to outer space via radiators at 250 K. Modified to cool scientific instrumentation on Earth with some loss of efficiency. Require no power during quick cooldown and low heating power during relatively long recharge periods.

Johnson, AL; Jones, Jack A.

1994-01-01

340

49 CFR 173.5b - Portable and mobile refrigeration systems.  

Code of Federal Regulations, 2010 CFR

These refrigeration systems are used at field sites to cool (pre-cool) produce before the produce is loaded into trucks or railcars for market or used to supplement stationary refrigeration systems during peak harvest...

2010-10-01

341

49 CFR 173.5b - Portable and mobile refrigeration systems.  

Code of Federal Regulations, 2010 CFR

These refrigeration systems are used at field sites to cool (pre-cool) produce before the produce is loaded into trucks or railcars for market or used to supplement stationary refrigeration systems during peak harvest...

2009-10-01

342

49 CFR 173.5b - Portable and mobile refrigeration systems.  

Code of Federal Regulations, 2013 CFR

These refrigeration systems are used at field sites to cool (pre-cool) produce before the produce is loaded into trucks or railcars for market or used to supplement stationary refrigeration systems during peak harvest...

2013-10-01

343

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

344

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

345

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

346

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

347

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

348

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

349

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

350

Magnetic refrigeration for low-temperature applications  

NASA Astrophysics Data System (ADS)

The application of refrigeration at low temperatures ranging from production of liquid helium for medical imaging systems to cooling of infrared sensors on surveillance satellites is discussed. Cooling below about 15 K with regenerative refrigerators is difficult because of the decreasing thermal mass of the regenerator compared to that of the working material. In order to overcome this difficulty with helium gas as the working material, a heat exchanger plus a Joule-Thomson or other exponder is used. Regenerative magnetic refrigerators with magnetic solids as the working material have the same regenerator problem as gas refrigerators. This problem provides motivation for the development of nonregenerative magnetic refrigerators that span approximately 1 K to approximately 0 K. Particular emphasis is placed on high reliability and high efficiency. Calculations indicate considerable promise in this area. The principles, the potential, the problems, and the progress towards development of successful 4 to 20 K magnetic refrigerators are discussed.

Barclay, J. A.

1985-05-01

351

Sorption cryogenic refrigeration - Status and future  

NASA Technical Reports Server (NTRS)

The operation principles of sorption cryogenic refrigeration are discussed. Sorption refrigerators have virtually no wear-related moving parts, have negligible vibration, and offer extremely long life (at least ten years), making it possible to obtain efficient, long life and low vibration cooling to as low as 7 K for cryogenic sensors. The physisorption and chemisorption systems recommended for various cooling ranges down to 7 K are described in detail. For long-life cooling at 4-5 K temperatures, a hybrid chemisorption-mechanical refrigeration system is recommended.

Jones, Jack A.

1988-01-01

352

Refrigerator temperature and defrost control  

SciTech Connect

This patent describes a refrigerator having cooling means including an evaporator and a compressor for cooling a refrigerated compartment. The compressor has first and second power terminals and defrost means for heating the evaporator to remove frost. The defrost means has first and second power terminals, and a source of power coupled to first and second power conductors, an electrical control for controlling the application of power to the power terminals of each of the compressor and the defrost means. The control comprises: defrost initiation means for producing a defrost initiation signal upon a determination that the energization of the defrost means is desired.

Janke, D.E.

1987-05-12

353

New He-3 Refrigerator for Space Applications.  

National Technical Information Service (NTIS)

Helium three (He-3) refrigerators capable of reaching 0.3 K in space with liquid helium cryogen cooling stages at approximately 1.8 K were already developed to the point of being tested on sounding rockets. A new design of He-3 refrigerator incorporating ...

C. I. Jewell G. Dalloglio W. Fischer L. Piccirillo L. Pizzo

1991-01-01

354

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

355

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

356

Application of magnetic refrigeration and its assessment  

NASA Astrophysics Data System (ADS)

Magnetic refrigeration has the potential to replace conventional refrigeration—with often problematic refrigerants—in several niche markets or even some main markets of the refrigeration domain. Based on this insight, for the Swiss Federal Office of Energy a list of almost all existing refrigeration technologies was worked out. Then an evaluation how good magnetic refrigeration applies to each of these technologies was performed. For this purpose a calculation tool to determine the coefficient of performance ( COP) and the exergy efficiency as a function of the magnetic field strength and the rotation frequency of a rotary-type magnetic refrigerator was developed. The evaluation clearly shows that some application domains are more ideal for a replacement of conventional refrigerators by their magnetic counterparts than others. In the pre-study, four good examples were chosen for a more comprehensive investigation and working out of more detailed results. In this article, the calculation method is briefly described. COP values and exergy efficiencies of one very suitable technology, namely the magnetic household refrigerator, are presented for different operation conditions. Summarizing, it is stated that magnetic refrigeration is a serious environmentally benign alternative to some conventional cooling, refrigeration and air-conditioning technologies.

Kitanovski, Andrej; Egolf, Peter W.

2009-04-01

357

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

358

Thermodynamic study of air-cycle and mercury-vapor-cycle systems for refrigerating cooling air for turbines or other components  

NASA Technical Reports Server (NTRS)

An analysis of air refrigeration systems indicated that air cycles are generally less satisfactory than simple heat exchangers unless high component efficiencies and high values of heat-exchanger effectiveness can be obtained. A system employing a mercury-vapor cycle appears to be feasible for refrigerating air that must enter the system at temperature levels of approximately 1500 degrees R, and this cycle is more efficient than the air cycle. Weight of the systems was not considered. The analysis of the systems is presented in a generalized dimensionless form.

Nachtigall, Alfred J; Freche, John C; Esgar, Jack B

1956-01-01

359

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

360

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

361

Low cost microminiature refrigerators for large unit volume applications  

NASA Technical Reports Server (NTRS)

Photolithographic techniques were employed to fabricate small Joule-Thomson refrigerators in laminated substrates. The gas passages of a J-T refrigerator are formed by etching channels as narrow as 50 microns and as shallow as 5 microns in glass plates which are laminated together. Circular refrigerators on the order of 1.5 centimeters in diameter and .75 millimeters thick were produced which cool down to cryogenic temperatures in a few seconds, using Argon or Nitrogen, with no vacuum or radiation insulation. Smaller refrigerators are developed for both faster cooldown and low refrigeration capacity applications. By using this technology, custom refrigerators can be designed to meet specific application requirements.

Duboc, R. M., Jr.

1983-01-01

362

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

363

Performance Evaluation of a 4.5 kW (1.3 Refrigeration Tons) Air-Cooled Lithium Bromide/Water Solar Powered (Hot-Water-Fired) Absorption Unit  

SciTech Connect

During the summer months, air-conditioning (cooling) is the single largest use of electricity in both residential and commercial buildings with the major impact on peak electric demand. Improved air-conditioning technology has by far the greatest potential impact on the electric industry compared to any other technology that uses electricity. Thermally activated absorption air-conditioning (absorption chillers) can provide overall peak load reduction and electric grid relief for summer peak demand. This innovative absorption technology is based on integrated rotating heat exchangers to enhance heat and mass transfer resulting in a potential reduction of size, cost, and weight of the "next generation" absorption units. Rotartica Absorption Chiller (RAC) is a 4.5 kW (1.3 refrigeration tons or RT) air-cooled lithium bromide (LiBr)/water unit powered by hot water generated using the solar energy and/or waste heat. Typically LiBr/water absorption chillers are water-cooled units which use a cooling tower to reject heat. Cooling towers require a large amount of space, increase start-up and maintenance costs. However, RAC is an air-cooled absorption chiller (no cooling tower). The purpose of this evaluation is to verify RAC performance by comparing the Coefficient of Performance (COP or ratio of cooling capacity to energy input) and the cooling capacity results with those of the manufacturer. The performance of the RAC was tested at Oak Ridge National Laboratory (ORNL) in a controlled environment at various hot and chilled water flow rates, air handler flow rates, and ambient temperatures. Temperature probes, mass flow meters, rotational speed measuring device, pressure transducers, and a web camera mounted inside the unit were used to monitor the RAC via a web control-based data acquisition system using Automated Logic Controller (ALC). Results showed a COP and cooling capacity of approximately 0.58 and 3.7 kW respectively at 35 C (95 F) design condition for ambient temperature with 40 C (104 F) cooling water temperature. This is in close agreement with the manufacturer data of 0.60 for COP and 3.9 kW for cooling capacity. This study resulted in a complete performance map of RAC which will be used to evaluate the potential benefits of rotating heat exchangers in making the "next-generation" absorption chillers more compact and cost effective without any significant degradation in the performance. In addition, the feasibility of using rotating heat exchangers in other applications will be evaluated.

Zaltash, Abdolreza [ORNL; Petrov, Andrei Y [ORNL; Linkous, Randall Lee [ORNL; Vineyard, Edward Allan [ORNL

2007-01-01

364

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

365

Solar-powered cooling system  

DOEpatents

A solar-powered adsorption-desorption refrigeration and air conditioning system uses nanostructural materials made of high specific surface area adsorption aerogel as the adsorptive media. Refrigerant molecules are adsorbed on the high surface area of the nanostructural material. A circulation system circulates refrigerant from the nanostructural material to a cooling unit.

Farmer, Joseph C

2013-12-24

366

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

367

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

368

A rocket-borne He-3 refrigerator  

NASA Technical Reports Server (NTRS)

A self-contained, recyclable He-3 refrigerator suitable for use in space has been developed. The refrigerator is compact, has no moving parts, and requires only electrical connections and thermal contact in order to operate from a 2 K cold stage. A charcoal adsorption pump is used to efficiently condense and cool the He-3. Sintered copper confines the He-3 to the evaporator in zero-gravity and, in fact, allows the refrigerator to operate upside-down in the laboratory. Mounted on a 2 K cold stage, the refrigerator provides 100 microwatts of cooling power at 346 mK, with a 7 hour hold time. On a 1.5 K cold stage, the lowest temperature achieved is 277 mK. The refrigerator has been vibration tested at 7.5 G amplitude from 30 to 400 Hz and 15 G amplitude from 400 to 2000 Hz.

Duband, L.; Alsop, D.; Lange, A.; Kittel, P.

1990-01-01

369

Dynamic design of gas sorption J-T refrigerator  

Microsoft Academic Search

A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts is desirable for long-term sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed

C. K. Chan

1986-01-01

370

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

371

Enclosure for thermoelectric refrigerator and method  

NASA Technical Reports Server (NTRS)

An enclosed structure is provided for use with a refrigerator having a door assembly. The enclosed structure preferably contains superinsulation materials and a plurality of matching drawers. The enclosed structure preferably includes corner joints which minimize thermal energy transfer between adjacent superinsulation panels. The refrigerator may include a cooling system having a thermoelectric device for maintaining the temperature within the refrigerator at selected values. If desired, a fluid cooling system and an active gasket may also be provided between the door assembly and the enclosed structure. The fluid cooling system preferably includes a second thermoelectric device to maintain the temperature of fluid flowing through the active gasket at a selected value. The drawers associated with the refrigerator may be used for gathering, processing, shipping and storing food or other perishable items.

Park, Brian V. (Inventor); McGrath, Ralph D. (Inventor)

1997-01-01

372

Absorption refrigeration machine driven by solar heat  

NASA Astrophysics Data System (ADS)

A mathematical model of a single and a two stage solar absorption refrigeration system is developed in which data of collectors and weather data can be implicated. The influence of the generator, the absorber efficiencies, and the cooling temperature on the coefficient of performance (COP) of a single and two stage absorption refrigeration process are investigated. For low generator temperatures the absorber efficiency has more influence on COP than the generator efficiency. Only spectral selective double window and high performance collectors can be used for air cooled solar absorption refrigeration systems at an evaporator temperature of -5 C. It is concluded that a water cooled solar absorption refrigeration system in combination with a solar tapwater installation for household use can be achieved with 6 to 8 square meters high performance collector area.

Keizer, C.; Liem, S. H.

1980-04-01

373

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

374

Comparative efficiencies and implications for greenhouse gas emissions of chiller refrigerants  

Microsoft Academic Search

This paper summarizes analyses of refrigerant options for chillers. Chillers are ma- chines that cool water or other liquids for use in large air-conditioning and refrigeration systems. Their operation for comfort and process cooling consumes substantial energy with resulting green- house gas (GHG) emissions. Moreover, leaked and otherwise released refrigerants act as GHGs, also contributing to global climate change. This

James M. Calm

2005-01-01

375

Solar powered cooling device  

SciTech Connect

The system contains an unique solar collector for transferring heat energy from the sun to a solution comprising a two-phase refrigerant and a fluid absorbent. Solar radiation causes a vaporization of the refrigerant which exits from the solar panel through a separate path from the remainder of the fluid. The vaporized refrigerant is returned to a liquid state and passed through an evaporator in a lower pressure environment for producing a cooling effect. The refrigerant is recombined with the absorbent and returned to the solar collector in a high pressure environment. Three modes of operation are included in the system. Continuous cooling is the first mode. The second mode consists of storing the liquid refrigerant after separation from the refrigerant absorbent fluid. The refrigerant and absorbent are stored for future use. The third mode of operation provides cooling in the absence of solar radiation by the use of the stored refrigerant and subsequent combination of the refrigerant with absorbent which fluid is then stored in a separate reservoir. The system also is provided with a solar tracking arrangement by which one or more solar collectors will be automatically oriented directly toward the sun for assuring maximum utilization of the sun's energy.

Ferriera, C.R.

1981-08-04

376

Wheel-type magnetic refrigerator  

DOEpatents

The disclosure is directed to a wheel-type magnetic refrigerator capable of cooling over a large temperature range. Ferromagnetic or paramagnetic porous materials are layered circumferentially according to their Curie temperature. The innermost layer has the lowest Curie temperature and the outermost layer has the highest Curie temperature. The wheel is rotated through a magnetic field perpendicular to the axis of the wheel and parallel to its direction of rotation. A fluid is pumped through portions of the layers using inner and outer manifolds to achieve refrigeration of a thermal load.

Barclay, J.A.

1982-01-20

377

Pot-in-Pot Refrigeration  

NSDL National Science Digital Library

In this activity (on page 2 of PDF), learners create a low-tech refrigerator that requires no electricity to keep food from spoiling. It uses only clay pots, one smaller than the other and separated by wet sand. As the water evaporates from the sand, it lowers the temperature inside the inner pot, similar to how evaporation from a sweaty person lowers the person's body temperature. This "refrigerator" with no moving parts is great for exploring evaporative cooling, as well as scientific innovation, especially since it has been used successfully in Africa.

Omsi

2004-01-01

378

Mixed refrigerant Joule-Thomson sorption cryocoolers  

NASA Astrophysics Data System (ADS)

Joule-Thomson (JT) sorption cryocooling is the most mature technology for cooling from a normal Room-Temperature (RT) down to temperatures below 100 K in the absence of moving parts. Therefore, high reliability and no vibrations are attainable, in comparison with other cryocoolers. Cooling to 80 - 100 K with JT cryocoolers is often implemented with pure nitrogen. Alternatively, mixed refrigerants have been suggested for reducing the operating pressures to enable closed cycle cryocooling. There is a variety of publications describing nitrogen sorption cryocoolers with different configurations of sorption compressors. In the present research we suggest a novel sorption JT cryocooler that operates with a mixed refrigerant. Merging of sorption cryocooling and a mixed refrigerant enables the use of a simple, single stage compressor for cooling to 80 - 100 K, lower operating temperatures of the sorption cycle, and thus - reduced power consumption. In previous studies we have analyzed sorption compressors for mixed gases and mixed refrigerants for JT cryocoolers, separately. In this paper the option of mixed refrigerant sorption JT cryocoolers is explored. The considerations for developing mixed refrigerants to be driven by sorption compressors and to be utilized with JT cryocoolers are provided. It appears that, unlike with pure nitrogen, mixed refrigerants can be suitable for JT cryocooling with a single stage sorption compressor.

Tzabar, Nir; Grossman, Gershon

2014-01-01

379

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

380

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

381

The optimal performance of an irreversible absorption refrigerator  

NASA Astrophysics Data System (ADS)

A new model is presented for an irreversible absorption refrigerator, in which not only the irreversibilities of heat conduction but also the irreversibilities resulting from the friction, eddy and other irreversible effects inside the working fluid are considered. The influence of these irreversible effects on the performance of an absorption refrigerator with continuous flow is investigated. The relation among the optimal refrigeration coefficient, cooling rate and overall heat-transfer area of the refrigerator is derived. Some new bounds are determined and some significant problems are discussed. The conclusions obtained here are of importance to the optimal design and performance improvement of an absorption refrigerator.

Lin, Guoxing; Yan, Zijun

1997-07-01

382

Counterflow absorber for an absorption refrigeration system  

DOEpatents

An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

Reimann, Robert C. (Lafayette, NY) [Lafayette, NY

1984-01-01

383

Dipole moments of seven partially halogenated ethane refrigerants  

SciTech Connect

Dielectric constant measurements have been performed on seven partially halogenated ethanes, currently being considered as alternative refrigerants, in the gaseous state over the range 305-415 K in order to determine their dipole moments. Argon was also studied to test the apparatus. Five of the refrigerants have temperature-independent moments: R125 (CF{sub 3}CHF{sub 2}), {mu} = 1.563 {plus minus} 0.005 D; R134a (CF{sub 3}CH{sub 2}F), {mu} = 2.058 {plus minus} 0.010 D; R143a (CF{sub 3}CH{sub 3}), {mu} = 2.340 {plus minus} 0.010 D; R152a (CHF{sub 2}CH{sub 3}), {mu} = 2.262 {plus minus} 0.008 D; and R124 (CF{sub 3}CHClF), {mu} = 1.469 {plus minus} 0.012 D. Two refrigerants have conformer-dependent moments, making their time-averaged moments temperature dependent: R134 (CHF{sub 2}CHF{sub 2}), with a moment ranging from 0.991 {plus minus} 0.004 D at 309 K to 1.250 {plus minus} 0.004 D at 413 K; and R143 (CHF{sub 2}CH{sub 2}F), where the moment ranges from 1.680 {plus minus} 0.001 D at 309 K to 1.745 {plus minus} 0.001 D at 410 K. Accurate estimation of a molecule's temperature-dependent dipole moment requires an independent determination of its polarizability; this determination has been made from index of refraction measurements. Where possible, the present results are compared with earlier determinations of dipole moments. In all but one instance, the agreement is good.

Meyer, C.W.; Morrison, G. (National Inst. of Standards and Technology, Gaithersburg, MD (United States))

1991-05-02

384

Auxiliary outside air refrigeration system  

SciTech Connect

An auxiliary outside air refrigeration system is described for cooling an enclosure comprising: a conventional refrigeration system operably disposed to cool the air inside the enclosure; a first airflow passage connecting the interior of the enclosure with a source of ambient air; a motorized outside air fan positioned to move cooler air from the exterior of the enclosure through the first airflow passage into the enclosure; a second airflow passage connecting the interior of the enclosure with the exterior of the enclosure to exhaust warmer air from the enclosure; a temperature sensor to sense the temperature of the outside air; a temperature sensor to sense the temperature of the air inside the enclosure; a thermostatic control means in communication with the inside and outside temperature sensors and in electrical communication with the outside air fan whereby the outside air fan is actuated whenever the air inside of the enclosure is warmer than a first pre-determined temperature and the outside atmospheric air is cooler than a first pre-determined number of degrees cooler than the air inside the enclosure; the outside air fan being de-actuated whenever the outside air temperature is warmer than a second predetermined number of degrees cooler than the air temperature inside the enclosure and, a thermostatic control means by which the compressor of the conventional refrigeration system is actuated whenever the temperature of the air inside the enclosure is above a third pre-determined temperature which is warmer than the cut-in temperature of the enclosure for the outside air refrigeration system, such that the compressor does not operate as long as the outside air refrigeration system is effectively cooling the air inside the enclosure.

Travers, R.H.

1993-08-31

385

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

386

Mathematical analysis of a Vuilleumier refrigerator.  

NASA Technical Reports Server (NTRS)

A comprehensive analysis of the Vuilleumier refrigerator was conducted. This analysis includes the effects of nonisothermal gas heat addition and rejection, hot and cold regenerator inefficiencies, conduction losses, and gas leakage losses. A computer program was written which solves the equations resulting from the analysis. The program calculates internal pressures, temperatures, and gas flow rates as functions of refrigerator crank angle, as well as overall refrigerator cooling load and power input. Comparisons between the program results and available data show good agreement, with a marked improvement over the predictions of the ideal model.

Sherman, A.

1971-01-01

387

Direct-Circulation Stirling-Cycle Refrigerator  

NASA Technical Reports Server (NTRS)

In proposed cryogenic system, cold working fluid (helium) circulated directly from Stirling-cycle refrigerator machinery through loop of tubing to provide 15 W of cooling power at temperature of 80 K to scientific instruments or other devices located at some distance from machinery. (Separation of cooled devices from machinery may be dictated by engineering requirements including, need to isolate cooled devices from vibrations of machinery.) Advantages include less complexity, smaller size, lighter weight, and lower power consumption.

Ellison, Woody; Kohuth, Randall, Sr.

1995-01-01

388

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

389

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

390

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

391

Performance analysis and optimization of a single barrier solid-state thermionic refrigerator with external heat transfer  

Microsoft Academic Search

A model of a single barrier solid-state thermionic refrigerator with external heat transfer is established in this paper. The performance of the refrigerator is analyzed and optimized by using the combination of finite time thermodynamics and non-equilibrium thermodynamics. The general expressions for cooling load and coefficient of performance (COP) of the refrigerator are derived. The optimum regions of cooling load

ZE-MIN DING; LIN-GEN CHEN; FENG-RUI SUN

2012-01-01

392

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

393

Review on solar-driven ejector refrigeration technologies  

Microsoft Academic Search

The objective of this paper is to provide a literature review on solar-driven ejector refrigeration systems and to give useful guidelines regarding background and operating principles of ejector. The development history and recent progress in solar-driven ejector refrigeration systems are reported and categorized. It shows that solar-driven ejector refrigeration technologies are not only can serve the needs for cooling requirements

J. M. Abdulateef; K. Sopian; M. A. Alghoul; M. Y. Sulaiman

2009-01-01

394

IEA Annex 26: Advanced Supermarket Refrigeration/Heat Recovery Systems  

SciTech Connect

With increased concern about the impact of refrigerant leakage on global warming, a number of new supermarket refrigeration system configurations requiring significantly less refrigerant charge are being considered. In order to help promote the development of advanced systems and expand the knowledge base for energy-efficient supermarket technology, the International Energy Agency (IEA) established IEA Annex 26 (Advanced Supermarket Refrigeration/Heat Recovery Systems) under the ''IEA Implementing Agreement on Heat Pumping Technologies''. Annex 26 focuses on demonstrating and documenting the energy saving and environmental benefits of advanced systems design for food refrigeration and space heating and cooling for supermarkets. Advanced in this context means systems that use less energy, require less refrigerant and produce lower refrigerant emissions. Stated another way, the goal is to identify supermarket refrigeration and HVAC technology options that reduce the total equivalent warming impact (TEWI) of supermarkets by reducing both system energy use (increasing efficiency) and reducing total refrigerant charge. The Annex has five participating countries: Canada, Denmark, Sweden, the United Kingdom, and the United States. The working program of the Annex has involved analytical and experimental investigation of several candidate system design approaches to determine their potential to reduce refrigerant usage and energy consumption. Advanced refrigeration system types investigated include the following: distributed compressor systems--small parallel compressor racks are located in close proximity to the food display cases they serve thus significantly shortening the connecting refrigerant line lengths; secondary loop systems--one or more central chillers are used to refrigerate a secondary coolant (e.g. brine, ice slurry, or CO2) that is pumped to the food display cases on the sales floor; self-contained display cases--each food display case has its own refrigeration unit; low-charge direct expansion--similar to conventional multiplex refrigeration systems but with improved controls to limit charge. Means to integrate store HVAC systems for space heating/cooling with the refrigeration system have been investigated as well. One approach is to use heat pumps to recover refrigeration waste heat and raise it to a sufficient level to provide for store heating needs. Another involves use of combined heating and power (CHP) or combined cooling, heating, and power (CCHP) systems to integrate the refrigeration, HVAC, and power services in stores. Other methods including direct recovery of refrigeration reject heat for space and water heating have also been examined.

Baxter, VAN

2003-05-19

395

Development of a solar-powered passive ejector cooling system  

Microsoft Academic Search

This paper describes the development of an ejector refrigeration system that is powered by solar thermal energy. The cooling system contains no active parts and is therefore deemed passive. Water is used as the refrigerant though other natural refrigerants could be used for lower temperature operation. A prototype system was built with a nominal cooling capacity of 7 kW. This

V. M Nguyen; S. B Riffat; P. S Doherty

2001-01-01

396

Results on the Characterization of Gas Hydrate Formation in a Direct Contact Heat Pump Cool Storage System.  

National Technical Information Service (NTIS)

This report describes an investigation of a latent cool storage system which employs a refrigerant gas hydrate as the storage medium. A refrigerant gas hydrate is a compound consisting of a refrigerant gas molecule contained within a crystalline water mol...

M. P. Ternes

1985-01-01

397

A Nanosize Quantum-Dot Photoelectric Refrigerator  

NASA Astrophysics Data System (ADS)

We investigate the thermodynamic performance of a nanosized photoelectric refrigerator consisting of two single energy levels embedded between two reservoirs at different temperatures. Based on the quantum master equation, expressions for the cooling power and coefficient of performance (COP) of the refrigerator are derived. The characteristic curves between the cooling power and COP are plotted. Moreover, the optimal performance parameters are analyzed by the numerical calculation and graphic method. The influence of the nonradiative processes on the performance characteristics and optimal performance parameters are discussed in detail.

Li, Cong; Zhang, Yan-Chao; He, Ji-Zhou

2013-10-01

398

Analysis of crystallization risk in double effect absorption refrigeration systems  

Microsoft Academic Search

Absorption refrigeration systems are an alternative to vapor compression ones in cooling and refrigeration applications. In comparison with single effect absorption units, double effect systems have improved performance. Also, they are more available commercially than the other multi effect absorption cycles. An important challenge in the operation of such systems is the possibility of crystallization within them. This is especially

L. Garousi Farshi; S. M. Seyed Mahmoudi; M. A. Rosen

2011-01-01

399

MEPR versus EEPR valves in open supermarket refrigerated display cabinets  

Microsoft Academic Search

This paper presents the comparative experimental field performance of mechanical evaporator pressure regulating valves (MEPR) and electronic evaporator pressure regulating valves (EEPR) under the identical operating conditions of supermarket open multi-deck refrigerated display cabinets. The main goal of the supermarket refrigeration system design is to keep the displayed product at the required constant temperature, while minimising the cooling load to

A. Tahir; P. K. Bansal

2005-01-01

400

On the thermodynamic cycle of the low temperature GM refrigerator  

Microsoft Academic Search

It is ascertained that the helium refrigerant responsible for Simon expansion cooling in the cold space is restricted to circulate within the cold space and the low temperature regenerator. It is recompressed in the regenerator void volume instead of in the ambient temperature compressor. Thus, part of the compression heat will be carried by the heated helium refrigerant into the

Hong Chao-Sheng; Xu Xiang-Dong

1994-01-01

401

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

402

Operation and maintenance of Fermilab's satellite refrigerator expansion engines.  

National Technical Information Service (NTIS)

Fermilab's superconducting Tevatron accelerator is cooled to liquid helium temperatures by 24 satellite refrigerators, each of which uses for normal operations a reciprocating 'wet' expansion engine. These expanders are basically Process System (formerly ...

W. M. Soyars

1996-01-01

403

Shuttle kit freezer refrigeration unit conceptual design  

NASA Technical Reports Server (NTRS)

The refrigerated food/medical sample storage compartment as a kit to the space shuttle orbiter is examined. To maintain the -10 F in the freezer kit, an active refrigeration unit is required, and an air cooled Stirling Cycle refrigerator was selected. The freezer kit contains two subsystems, the refrigeration unit, and the storage volume. The freezer must provide two basic capabilities in one unit. One requirement is to store 215 lbs of food which is consumed in a 30-day period by 7 people. The other requirement is to store 128.3 lbs of medical samples consisting of both urine and feces. The unit can be mounted on the lower deck of the shuttle cabin, and will occupy four standard payload module compartments on the forward bulkhead. The freezer contains four storage compartments.

Copeland, R. J.

1975-01-01

404

Results on the characterization of gas hydrate formation in a direct contact heat pump cool storage system  

Microsoft Academic Search

This report describes an investigation of a latent cool storage system which employs a refrigerant gas hydrate as the storage medium. A refrigerant gas hydrate is a compound consisting of a refrigerant gas molecule contained within a crystalline water molecule cage. In this system, the storage component is incorporated directly into the refrigeration cycle, replacing the conventional evaporator. The refrigerant

M. P. Ternes

1985-01-01

405

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

406

Development of a Mixed-Refrigerant Joule-Thomson Microcryocooler  

Microsoft Academic Search

We discuss in this paper the development of a mixed-refrigerant Joule-Thomson microcryocooler (MCC) to support on-chip cooling of high temperature superconducting electronics that require less than 5 mW of net refrigeration at about 80 K. Some applications include the cooling of infrared and terahertz imaging sensors that operate at about 77 K. Terahertz sensors can be used for the imaging

P. E. Bradley; R. Radebaugh; M. Huber

407

Performance of an HCFC22-based vapour absorption refrigeration system  

Microsoft Academic Search

A single-stage vapour absorption refrigeration system (VARS) is tested with monochlorodifluoromethane (HCF22) as refrigerant and different absorbents: dimethylether of tetraethylene glycol (DMETEG) and dimethyl acetamide (DMA). The influence of generator temperatures in the range 75–95°C, which represents low-grade heat sources, is studied. Cooling water temperatures were varied between 20 and 30°C. Two cases of cooling water flow paths are considered,

M. Fatouh; S. Srinivasa Murthy

1995-01-01

408

Gas hydrate cool storage system  

Microsoft Academic Search

This invention is a process for formation of a gas hydrate to be used as a cool storage medium using a refrigerant in water. Mixing of the immiscible refrigerant and water is effected by addition of a surfactant and agitation. The difficult problem of subcooling during the process is overcome by using the surfactant and agitation and performance of the

Mark P. Ternes; Robert J. Kedl

1985-01-01

409

Macroscale refrigeration by nanoscale electron transport  

NASA Astrophysics Data System (ADS)

We demonstrate a general-purpose solid-state refrigerator for sub-Kelvin temperatures based on the tunneling of hot electrons through normal-metal/insulator/superconductor (NIS) junctions. Previous devices using this cooling principle fell short of general-purpose refrigerators since they could not be coupled to arbitrary payloads. To create a viable refrigerator, we developed optimized NIS structures and techniques to couple multiple such structures to arbitrary objects. Using three linked NIS devices, we reduced the temperature of a 1.9 cm3 copper stage from 290 mK to 256 mK with 700 pW of cooling power at 290 mK. We present plans to achieve base temperatures near 100 mK.

Lowell, Peter J.; O'Neil, Galen C.; Underwood, Jason M.; Ullom, Joel N.

2013-02-01

410

Field Testing of an Advanced Low-Charge Supermarket Refrigeration System  

Microsoft Academic Search

A field test was conducted to compare the performance of multiplex and distributed supermarket refrigeration systems. Two supermarkets in the vicinity of Worcester, Massachusetts were the sites utilized for the field test. One store was equipped with a multiplex refrigeration system that had 3 compressor racks and air-cooled condensers. At the second store, a low-refrigerant-charge distributed refrigeration system was installed

David H. Walker

411

Construction of a 2 kW /4 K Helium Refrigerator for HT-7U  

NASA Astrophysics Data System (ADS)

Superconducting magnets of toroidal field (TF) and poloidal field (PF) of HT-7U tokamak are all made of NbTi/Cu Cable-in-Conduit Conductor (CICC), and cooled with a forced flow supercritical helium of 3.8 K. A helium refrigerator with an equivalent capacity of 2 kW/4 K will be constructed. This paper presents the design of the helium refrigerator process, the thermodynamics of the refrigeration cycle and the refrigerator equipments.

Bai, Hong-yu; Bi, Yan-fang; Wang, Jing-rong; Zhuang, Ming; Zhu, Ping; Zhang, Qi-yong; Sheng, Lin-hai

2002-06-01

412

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

413

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

414

Self-actuating heat switches for redundant refrigeration systems  

NASA Technical Reports Server (NTRS)

A dual refrigeration system for cooling a sink device is described, which automatically thermally couples the cold refrigerator to the sink device while thermally isolating the warm refrigerator from the sink device. The system includes two gas gap heat switches that each thermally couples one of the refrigerators to the sink device, and a pair of sorption pumps that are coupled through tubes to the heat switches. When the first refrigerator is operated and therefore cold, the first pump which is thermally coupled to it is also cooled and adsorbs gas to withdraw it from the second heat switch, to thereby thermally isolate the sink device from the warm second refrigerator. With the second refrigerator being warm, the second pump is also warm and desorbs gas, so the gas lies in the first switch, to close that switch and therefore thermally couple the cold first refrigerator to the sink device. Thus, the heat switches are automatically switched according to the temperature of the corresponding refrigerator.

Chan, Chung K. (inventor)

1988-01-01

415

Microporous Carbon Disks For Sorption Refrigerators  

NASA Technical Reports Server (NTRS)

Slow, carefully controlled pyrolysis found to turn polyvinylidene chloride disks into carbon disks having small pores and large surface areas. Disks exhibit high adsorptivities making them useful in krypton-sorption refrigerators. Carbons made from polyvinylidene chloride have greater adsorptive capacities. Thermal instability controlled and variability of product reduced by careful control of rates of heating, heating times, and rate of final cooling.

Munukutla, Lakshmi V.; Moore, Mark R.

1993-01-01

416

Review of solid adsorption solar refrigeration II  

Microsoft Academic Search

A review of the basic principles and theories of solid adsorption solar refrigeration is presented. The cycle performance thermodynamics is also reviewed, and the criteria for selection of adsorbent\\/adsorbent pairs are reported. The practically realised solar adsorption cooling systems were categorized by their adsorbate operating pressure ranges as low and high pressure systems, and their pertinent design features are given.

E. E. Anyanwu

2004-01-01

417

Stirling-Cycle Refrigerator Containing Piezoelectric Pumps  

NASA Technical Reports Server (NTRS)

Advanced Stirling-cycle cryogenic apparatus suitable for cooling sensitive infrared detectors to very low temperatures. Working fluid in refrigerator helium. Working fluid compressed and circulated by three piezoelectrically actuated diaphragm pumps offering advantages of greater reliability, relative simplicity, and lower cost.

Jalink, Antony, Jr.; Hellbaum, R. F.

1995-01-01

418

Compact, High-Performance Continuous Magnetic Refrigerator.  

National Technical Information Service (NTIS)

We present test results of the first adiabatic demagnetization refrigerator (ADR) that can produce continuous cooling at sub-kelvin temperatures. This system uses multiple stages that operate in sequence to cascade heat from a continuous stage up to a hea...

P. Shirron E. Canavan M. DiPirro M. Jackson T. King J. Panek J. Tuttle

2001-01-01

419

Refrigeration With And Of Solid State Devices  

Microsoft Academic Search

Abstract Solid state coolers are reliable, cheap and easy to scale down to microscopic scales, hence very promising for on chip refrigeration in microelectronics. The previous decade has shown tremendous interest for applications both in science and industry. In this thesis we present an overview on the state of the art possibilities and applications of solid state cooling in Microelectronic

Amar Ashok Jituri

2009-01-01

420

Regenerative sorption compressors for cryogenic refrigeration  

NASA Technical Reports Server (NTRS)

Dramatic efficiency improvements for sorption coolers appear possible with use of compressor heat regeneration techniques. The general theory of sorption compressor heat regeneration is discussed in this paper, and several design concepts are presented. These designs result in long-life, low-vibration cryocoolers that potentially have efficiencies comparable to Stirling refrigerators for 65 to 90 K spacecraft instrument cooling applications.

Bard, Steven; Jones, Jack A.

1990-01-01

421

A continuous low-temperature magnetic refrigerator  

Microsoft Academic Search

We report on recent progress in the development of a continuous adiabatic demagnetization refrigerator (ADR). Continuous operation avoids the constraints of long hold times and short recycle times that lead to the generally large mass of single-shot ADRs, allowing us to achieve an order of magnitude larger cooling power per unit mass. Our current design goal is 10 ?W of

P. J. Shirron; E. R. Canavan; M. J. DiPirro; M. Jackson; J. Panek; J. G. Tuttle

2002-01-01

422

A continuous low-temperature magnetic refrigerator  

Microsoft Academic Search

We report on recent progress in the development of a continuous adiabatic demagnetization refrigerator (ADR). Continuous operation avoids the constraints of long hold times and short recycle times that lead to the generally large mass of single-shot ADRs, allowing us to achieve an order of magnitude larger cooling power per unit mass. Our current design goal is 10 muW of

P. J. Shirron; E. R. Canavan; M. J. Dipirro; M. Jackson; J. Panek; J. G. Tuttle

2002-01-01

423

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

424

Ventilation Cooling: An Old Solution to New Problems. Part 1: The Economics.  

ERIC Educational Resources Information Center

This first article in a series about cooling classrooms by ventilation explains that energy consumption for one day of refrigeration cooling is equal to energy use for 35 days of ventilation cooling. Schools using only refrigeration cooling are passing up energy savings that could be provided by ventilation cooling. (Author/MLF)

DiMercurio, C.

1981-01-01

425

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

426

Development of the REFPROP database and transport properties of refrigerants. Final report  

SciTech Connect

This task consisted of developing Version 6.0 of the NIST Thermodynamic and Transport Properties of Refrigerants and Refrigerant Mixtures Database (REFPROP), entailing a complete revision of this database. This program is based on the most accurate pure fluid and mixture models currently available. The database development is further divided into the development of a graphical user interface and the development of Fortran subroutines which implement the property models. Three models are used for the thermodynamic properties of pure components, depending on the availability of data. The first is the modified Benedict-Webb-Rubin (MBWR) equation of state. It is capable of accurately representing the properties of a fluid over wide ranges of temperature, pressure, and density. The MBWR equation is the basis for the current international standard for the properties of R123. The second high-accuracy pure-fluid equation of state is written in terms of reduced molar Helmholtz free energy. This Helmholtz energy model is the basis for the international standard formulation for R134a. The third pure-fluid model is the extended corresponding states (ECS) model of Huber and Ely (1994). It is used for fluids with limited experimental data. The database calculates seventeen thermodynamic and transport properties, including surface tensions of pure fluids and mixtures. Commercialized blends, such as R407C and R410A, are predefined in the interface and are listed in a table.

McLinden, M.O.

1998-07-01

427

Correlation and prediction of the transport properties of refrigerants using two modified rough hard-sphere models  

SciTech Connect

Two methods are presented for the correlation and prediction of the viscosities and thermal conductivities of refrigerants R11, R12, R22, R32, R124, R125, R134a, R141b, and R152 and their mixtures. The first (termed RHS1) is a modified rough-hard-sphere method based on the smooth hard-sphere correlations of Assael et al. The method requires two or three parameters for characterizing each refrigerant but is able to correlate transport properties over wide ranges of pressure and temperature. The second method (RHS2) is also a modified rough-hard-sphere method, but based on an effective hard-sphere diameter for Lennard-Jones (LJ) fluids. The LJ parameters and the effective hard-sphere diameter required in this method are determined from a knowledge of the density-temperature behavior of the fluid at saturation. Comparisons with the rough-hard-sphere method of Assael and co-workers (RHS3) are shown. They also show that the RHS2 method can be used to correlate as well as predict the transport properties of refrigerants.

Teja, A.S.; King, R.K.; Sun, T.F. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Chemical Engineering] [Georgia Inst. of Tech., Atlanta, GA (United States). School of Chemical Engineering; Smith, R.L. Jr. [Tohoku Univ., Sendai (Japan). Dept. of Chemical Engineering] [Tohoku Univ., Sendai (Japan). Dept. of Chemical Engineering

1999-01-01

428

A Variable Refrigerant Flow Heat Pump Computer Model in EnergyPlus  

SciTech Connect

This paper provides an overview of the variable refrigerant flow heat pump computer model included with the Department of Energy's EnergyPlusTM whole-building energy simulation software. The mathematical model for a variable refrigerant flow heat pump operating in cooling or heating mode, and a detailed model for the variable refrigerant flow direct-expansion (DX) cooling coil are described in detail.

Raustad, Richard A. [Florida Solar Energy Center

2013-01-01

429

Novel materials for laser refrigeration  

SciTech Connect

The status of optical refrigeration of rare-earth-doped solids is reviewed, and the various factors that limit the performance of current laser-cooling materials are discussed. Efficient optical refrigeration is possible in materials for which {Dirac_h}{omega}{sub max} < E{sub p}/8, where {Dirac_h}{omega}{sub max} is the maximum phonon energy of the host material and E{sub p} is the pump energy of the rare-earth dopant. Transition-metal and OH{sup -}impurities at levels >100 ppb are believed to be the main factors for the limited laser-cooling performance in current materials. The many components of doped ZBLAN glass pose particular processing challenges. Binary fluoride glasses such as YF{sub 3}-LiF are considered as alternatives to ZBLAN. The crystalline system KPb{sub 2}CI{sub 5} :Dy{sup 3+} is identified as a prime candidate for high-efficiency laser cooling.

Hehlen, Markus P [Los Alamos National Laboratory

2009-01-01

430

Study on adsorption refrigeration cycle utilizing activated carbon fibers. Part 1. Adsorption characteristics  

Microsoft Academic Search

Thermal heat driven adsorption systems using natural refrigerants have been focused on the recent energy utilization trend. However, the drawbacks of these adsorption systems are their poor performance in terms of system cooling capacity and coefficient of performance (COP). The objective of this paper is to improve the performance of thermally powered adsorption cooling system by selecting new adsorbent–refrigerant pair.

Y. Hamamoto; K. C. A. Alam; B. B. Saha; S. Koyama; A. Akisawa; T. Kashiwagi

2006-01-01

431

Installation of 4K refrigerator in dilution refrigerator with nuclear demagnetization apparatus  

NASA Astrophysics Data System (ADS)

A Joule-Thomson (J-T) expansion refrigerator with a Gifford-McMahon (G-M) precooler was installed in a dilution refrigerator for use in long-term experiments such as a nuclear demagnetization experiment without the necessity for 4He transfer. A helium circulation system was constructed in which the boiled-off gas was precooled by a G-M refrigerator with strong cooling power and liquefied by a J-T loop heat exchanger. The dilution refrigerator was operated for three weeks without liquid 4He transfer as a test run for the system. The only maintenance needed was supplying of liquid nitrogen to the trap and cleaning it every other day. A vibration isolation system reduced heat leakage caused by vibration of the G-M refrigerator. Nuclear demagnetization was possible with this system and the nuclear stage was cooled down to submillikelvin temperatures. This system is applicable to various pieces of low temperature apparatus as well as dilution refrigerators because little modification of the cryostat is needed.

Matsumoto, K.; Okuda, Y.

432

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

433

Hydronic rooftop cooling systems  

DOEpatents

A roof top cooling unit has an evaporative cooling section that includes at least one evaporative module that pre-cools ventilation air and water; a condenser; a water reservoir and pump that captures and re-circulates water within the evaporative modules; a fan that exhausts air from the building and the evaporative modules and systems that refill and drain the water reservoir. The cooling unit also has a refrigerant section that includes a compressor, an expansion device, evaporator and condenser heat exchangers, and connecting refrigerant piping. Supply air components include a blower, an air filter, a cooling and/or heating coil to condition air for supply to the building, and optional dampers that, in designs that supply less than 100% outdoor air to the building, control the mixture of return and ventilation air.

Bourne, Richard C. (Davis, CA) [Davis, CA; Lee, Brian Eric (Monterey, CA) [Monterey, CA; Berman, Mark J. (Davis, CA) [Davis, CA

2008-01-29

434

Electronic refrigeration at the quantum limit.  

PubMed

We demonstrate quantum-limited electronic refrigeration of a metallic island in a low-temperature microcircuit. We show that matching the impedance of the circuit enables refrigeration at a distance, of about 50 microm in our case, through superconducting leads with a cooling power determined by the quantum of thermal conductance. In a reference sample with a mismatched circuit this effect is absent. Our results are consistent with the concept of electromagnetic heat transport. We observe and analyze the crossover between electromagnetic and quasiparticle heat flux in a superconductor. PMID:19519012

Timofeev, Andrey V; Helle, Meri; Meschke, Matthias; Möttönen, Mikko; Pekola, Jukka P

2009-05-22

435

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

436

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

437

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

438

Neon turbo-Brayton cycle refrigerator for HTS power machines  

NASA Astrophysics Data System (ADS)

We developed a prototype turbo-Brayton refrigerator whose working fluid is neon gas. The refrigerator is designed for a HTS (High Temperature Superconducting) power transformer and its cooling power is more than 2 kW at 65 K. The refrigerator has a turboexpander and a turbo-compressor, which utilize magnetic bearings. These rotational machines have no rubbing parts and no oil-components. Those make a long maintenance interval of the refrigerator. The refrigerator is very compact because our newly developed turbo-compressor is volumetrically smaller than a displacement type compressor in same operating specification. Another feature of the refrigerator is a wide range operation capability for various heat-loads. Cooling power is controlled by the input-power of the turbo-compressor instead of the conventional method of using an electric heater. The rotational speed of the compressor motor is adjusted by an inverter. This system is expected to be more efficient. We show design details, specification and cooling test results of the new refrigerator in this paper.

Hirai, Hirokazu; Hirokawa, M.; Yoshida, Shigeru; Nara, N.; Ozaki, S.; Hayashi, H.; Okamoto, H.; Shiohara, Y.

2012-06-01

439

Laser cooling by collisional redistribution of radiation  

Microsoft Academic Search

The general idea that optical radiation may cool matter was put forward 80 years ago. Doppler cooling of dilute atomic gases is an extremely successful application of this concept. More recently, anti-Stokes cooling in multilevel systems has been explored, culminating in the optical refrigeration of solids. Collisional redistribution of radiation has been proposed as a different cooling mechanism for atomic

Ulrich Vogl; Martin Weitz

2009-01-01

440

Method of cooling zinc halogen batteries  

Microsoft Academic Search

This disclosure relates to a method of cooling zinc halogen batteries which involves the use of a liquid-overfeed cooling system utilizing a fluorocarbon refrigerant or the like. This new method is adaptable for use in either cooling the battery store water during charge so that a solid halogen hydrate will form, or for use in cooling the battery electrolyte, or

Kodali

1981-01-01

441

Adaptive defrost control for a refrigerator  

SciTech Connect

A control is described for a refrigeration device having cooling apparatus including an evaporator, defrosting apparatus for removing frost from the evaporator and means for energizing the defrosting apparatus at the end of a cooling cycle to initiate a defrost cycle, comprising: detecting means for detecting the rate of change of evaporator temperature during a defrosting cycle; determining means for determining the length of time the rate of change of evaporator temperature remains at substantially zero; and establishing means for establishing the duration of a subsequent cooling cycle in dependence upon the determined length of time.

Janke, D.E.; Linstromberg, W.J.

1987-09-01

442

Absorption refrigerators and coolers. (Latest citations from the US Patent Bibliographic File with Exemplary Claims). Published Search  

SciTech Connect

The bibliography contains citations of selected patents concerning the design and application of absorption refrigeration systems. Citations cover refrigeration, cooling/heating, and chilling devices. Combination heat pump/absorption and mechanical/absorption refrigeration systems are included. (Contains a minimum of 172 citations and includes a subject term index and title list.)

Not Available

1994-08-01

443

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

444

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

445

Cryogenic refrigeration. (Latest citations from the Aerospace database). Published Search  

SciTech Connect

The bibliography contains citations concerning cryogenic refrigeration or cryocooling. Design, development, testing, and evaluation of cryogenic cooling systems are discussed. Design applications in spacecraft, magnet cooling, superconductors, liquid fuel storage, radioastronomy, and medicine are presented. Material properties at cryogenic temperatures and cryogenic rocket propellants are considered in separate bibliographies. (Contains 250 citations and includes a subject term index and title list.)

NONE

1993-09-01

446

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

447

An adiabatic demagnetization refrigerator for SIRTF  

NASA Technical Reports Server (NTRS)

An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.

Timbie, P. T.; Bernstein, G. M.; Richards, P. L.

1989-01-01

448

Short time cycles of purely quantum refrigerators.  

PubMed

Four stroke Otto refrigerator cycles with no classical analog are studied. Extremely short cycle times with respect to the internal timescale of the working medium characterize these refrigerators. Therefore, these cycles are termed sudden. The sudden cycles are characterized by the stable limit cycle, which is the invariant of the global cycle propagator. During their operation the states of the working medium possess significant coherence which is not erased in the equilibration segments due to the very short time allocated. This characteristic is reflected in a difference between the energy entropy and the Von Neumann entropy of the working medium. A classification scheme for sudden refrigerators is developed allowing simple approximations for the cooling power and coefficient of performance. PMID:23004710

Feldmann, Tova; Kosloff, Ronnie

2012-05-01

449

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

450

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

451

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

452

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

453

Method of operating a transport refrigeration system  

SciTech Connect

A method of enhancing the defrost cycle of a truck refrigeration system which lacks a dedicated prime mover of the internal combustion type, is described comprising the steps of: providing a transport refrigeration system having a first compressor operatively coupled to the engine of the associated truck, a second compressor operatively coupled to an electric motor, and a single refrigeration circuit including a condenser, evaporator, accumulator, and valve means operable to provide cooling and defrost cycles utilizing the discharge gas of one of the compressors, using the discharge gas of the first compressor in the single refrigeration circuit when the truck engine is operating, connecting the electric motor to an electrical stand-by source when the truck engine is not operating, using the discharge gas of the second compressor in the single refrigeration circuit when the electrical motor is connected to the electrical stand-by source, providing heat storage means in heat exchange relation with the accumulator, and providing electrical resistance means for continuously storing heat in the heat storage means while the single refrigeration circuit is connected to either one of the first and second compressors, at the lowest heat storage rate which will provide adequate heat build up between defrost cycles to vaporize liquified refrigerant introduced into the accumulator during a defrost cycle, the step of providing electrical resistance means including the steps of: connecting the electrical resistance means to the electrical system of the associated truck when the first compressor is operative, and connecting the electrical resistance means to an electrical stand-by source when the second compressor is operative.

Howland, L.L.

1988-01-26

454

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

455

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

456

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

457

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

458

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

459

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

460

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

461

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

462

Two-watt, 4-Kelvin closed cycle refrigerator performance  

NASA Technical Reports Server (NTRS)

A 2-watt, 4-K helium refrigerator using the Gifford-McMahon/Joule Thomson cycle is described. The unit features a removable displacer cylinder and high-efficiency, low-pressure drop heat exchangers. These improvements result in a 100 percent increase in cooling power over the existing Deep Space Network system. The effects of the heat exchanger efficiency and Gifford-McMahon expander performance on refrigerator capacity are also discussed.

Britcliffe, M.

1987-01-01

463

Custom-built research refrigerators for ultra-low temperature  

Microsoft Academic Search

The Janis line of ultra-low-temperature research refrigerators is presented. Cryogen-containing and cryogen-free 3He, 3He–4He dilution and adiabatic demagnetization refrigerators for the mK temperature range are described in detail and their possible use for cooling low-temperature sensors and detectors is discussed. A special emphasis is made on the Janis temperature scale down to 10mK, maintained with a newly designed compact CMN

Vladimir Shvarts; Lewis Bobb; Munir Jirmanus; Zuyu Zhao

2004-01-01

464

Experimental Investigation of a Traveling-wave Refrigerator  

NASA Astrophysics Data System (ADS)

In this paper, a thermally-driven thermoacoustic refrigerator without any moving parts is reported. This refrigeration system consists of a thermoacoustic Stirling heat engine and a thermoacoustic Stirling refrigerator. Both the subsystems are designed to operate on traveling-wave mode. In the experiment, it is found that the Gedeon DC-flow has significant negative effect on both the heat engine and the refrigerator. To suppress these DC-flows, two flexible membranes were inserted into the two subsystems. The experiment demonstrates that they have worked very well. Then extensive experiments had been made to test the influence of various parameters on refrigeration performance of the whole system. The system has so far achieved a no-load temperature of -65°C, a cooling capacity of about 270 W at -20°C and 405 W at 0°C. In summary, the thermoacoustic refrigeration technology reported here shows a good prospect in room-temperature cooling such as food refrigeration and air-conditioning.

Luo, E. C.; Dai, W.; Zhang, Y.; Ling, H.

2006-04-01

465

A solid-state refrigerator based on the electrocaloric effect  

NASA Astrophysics Data System (ADS)

The electrocaloric effect offers an attractive alternative to the Peltier effect for compact high-efficiency solid-state refrigeration. We report an implementation and experimental characterization of a continuous electrocaloric refrigeration cycle where we use switchable liquid-based thermal interfaces to achieve reliable high-contrast thermal switching between an electrocaloric material and a heat source/sink. The experimentally measured temporal temperature profiles of a cooling load agree well with transient heat transfer modeling results. Our work experimentally validates the feasibility of electrocaloric refrigeration and motivates further applied research on device development.

Jia, Yanbing; Sungtaek Ju, Y.

2012-06-01

466

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

467

Les fuites thermiques en refrigeration solaire (thermal losses in solar refrigeration)  

NASA Astrophysics Data System (ADS)

We show how the thermal losses determine the functioning of a solar refrigerator. After recalling preceding studies we define the parameters involved in an actual refrigeration and describe experiments carried out on a CaCl 2?NH 3 solid absorption couple. In order to calculate the losses, the sample to be cooled is a measured weight of water, the amount of which, compared with the water-value of the evaporator, modifies the thermal losses and the efficiency of the apparatus. The intermittence of the frigorigene regeneration phases requires optimisation of the apparatus so as to adapt it for possible use in tropical zones.

Flechon, J.; Machizaud, F.

468

Performance Analysis and Optimization of a Single-Barrier Solid-State Thermionic Refrigerator With External Heat Transfer  

Microsoft Academic Search

A model of a single-barrier solid-state thermionic refrigerator with external heat transfer is established in this paper. The performance of the refrigerator is analyzed and optimized by using the combination of finite-time thermodynamics and nonequilibrium thermodynamics. The general expressions for cooling load and coefficient of performance (COP) of the refrigerator are derived. The optimum regions of cooling load and COP

Ze-Min Ding; Lin-Gen Chen; Feng-Rui Sun

2012-01-01

469

Efficient adsorption refrigerators integrated with heat pipes  

Microsoft Academic Search

Several novel ideas to use heat pipes in adsorption water chiller or ice maker are presented in this paper. Experimental results have shown that the adsorption refrigerators are very efficient. The first example of such systems is a small scale silica gel–water adsorption water chiller with cooling power rated as 10kW; the system could be powered by 60–100°C hot water,

R. Z. Wang

2008-01-01

470

The B factor in multilayer thermionic refrigeration  

SciTech Connect

The figure of merit for multilayer thermionic refrigeration is discussed in terms of an effective B factor, which has a similar definition as the B factor in thermoelectrics. We show that high efficiencies for cooling or power generation are only obtained with very high values of this B factor. Such high values can only be attained because of the low thermal conductivity of multilayers. The B factor for thermionics is usually less than the one for thermoelectrics. (c) 1999 American Institute of Physics.

Vining, C. B. [ZT Services, 2203 Johns Circle, Auburn, Alabama 36830-7113 (United States)] [ZT Services, 2203 Johns Circle, Auburn, Alabama 36830-7113 (United States); Mahan, G. D. [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)

1999-12-15

471

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

472

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

473

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

474

Dynamic design of gas sorption J-T refrigerator  

NASA Technical Reports Server (NTRS)

A long-life Joule-Thomson refrigerator which is heat powered, involves no sealing, and has few mechanical parts is desirable for long-term sensor cooling in space. In the gas-sorption J-T refrigerator, cooling is achieved by gas sorption (either adsorption or absorption) processes. Currently, a modular, single-stage refrigerator is being designed and built to be operated at 20 K. The design was analyzed using a dynamic model, which is described here. The model includes the kinetics of the compressors and the heat switches, the heat transfer of the pre-coolers and the heat exchangers, the on/off ratio of the check valves, and the impedance of the J-T valve. The cooling power, the cycle time, and the operating conditions were obtained in terms of the power input, the heat sink temperature, and the J-T impedance.

Chan, C. K.