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Comparative Study of Environment Friendly Alternatives to R12 and R134a in Domestic Refrigerators

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In the present study, the possibility of using refrigerant blends of RE 170, R152a and R600a as alternative to the refrigerants R12 and R134a in domestic refrigerators working on Vapour Compression System has been assessed theoretically. R134a is currently used as the refrigerant in refrigerator replacing the ozone depleting refrigerant R12. Although R134a has no ozone depletion potential, it has relatively larger global warming potential (1300). For this reason performance of refrigerant mixtures containing R152a, RE170 and R600a are measured. The performance characteristics of domestic refrigerators were studied over a wide range of evaporation temperatures (-30°C to 30°C) and condensation temperatures (30°C, 40°C, 50°C) for various working fluids R12 R134a, refrigerants mixtures RE170/R152a and RE170/R600a.This study was carried out by comparing parameters such as pressure ratio, refrigerating effect, isentropic work, coefficient of performance, compressor power, volumetric cooling capacity discharge temperature and mass flow rate. The present study indicates a drop in replacement for R12 with blend RE170/R152 with the mass fractions of 50%/50%. Similarly R134a can be replaced with the blend (RE170/R 600a) with the mass fractions of 80%/20%.
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European Journal of Scientific Research
ISSN 1450-216X Vol. 92 No 2 December, 2012, pp.160-171
© EuroJournals Publishing, Inc. 2012
http://www.europeanjournalofscientificresearch.com
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators
A. Baskaran
Assistant Professor, Department of Mechanical Engineering
P.A.College of Engineering and Technology, Pollachi 642002, India
E-mail:boss120367@gmail.com
P. Koshy Mathews
Dean (R&D), Department of Mechanical Engineering
Kalaivani College of Technology, Coimbatore 641105, India
E-mail:pkoshymathews@yahoo.co.in
Abstract
In the present study, the possibility of using refrigerant blends of RE 170, R152a
and R600a as alternative to the refrigerants R12 and R134a in domestic refrigerators
working on Vapour Compression System has been assessed theoretically. R134a is
currently used as the refrigerant in refrigerator replacing the ozone depleting refrigerant
R12. Although R134a has no ozone depletion potential, it has relatively larger global
warming potential (1300). For this reason performance of refrigerant mixtures containing
R152a, RE170 and R600a are measured. The performance characteristics of domestic
refrigerators were studied over a wide range of evaporation temperatures (-30°C to 30°C)
and condensation temperatures (30°C, 40°C, 50°C) for various working fluids R12 R134a,
refrigerants mixtures RE170/R152a and RE170/R600a.This study was carried out by
comparing parameters such as pressure ratio, refrigerating effect, isentropic work,
coefficient of performance, compressor power, volumetric cooling capacity discharge
temperature and mass flow rate. The present study indicates a drop in replacement for R12
with blend RE170/R152 with the mass fractions of 50%/50%. Similarly R134a can be
replaced with the blend (RE170/R 600a) with the mass fractions of 80%/20%.
Keywords: Refrigerant blends, COP, R12, R134a, RE170, R152a, R600a
1. Introduction
For the past half century, chlorofluorocarbons (CFCs) have been used extensively in the field of
refrigeration due to their favorable characteristics. In particular, CFC12 has been predominantly used
for small refrigeration units including domestic refrigerator/freezers. Since the advent of the Montreal
Protocol, as the CFC12 has high ODP and GWP the refrigeration industry has been trying to find out
the best substitutes for ozone depleting substances. For a past decade, HFC134a has been used to
replace CFC12 used in refrigerators and automobile air conditioners. HFC134a has such favorable
characteristics as zero ozone depleting potential (ODP), non-flammability, stability, and similar vapor
pressure to that of CFC12. A recent survey, however, showed that the performance of HFC134a in
refrigerators with a proper compressor and lubricant is quite comparable to that of CFC12.
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators 161
In 1997 the Kyoto protocol was agreed by many nations calling for the reduction in emissions
of greenhouse gases including HFCs. Since the Global warming potential (GWP) of HFC134a is
relatively high (GWP1300) and also expensive, the production and use of HFC134a will be terminated
in the near future.
In an effort to reduce greenhouse gas emissions, R152a (difluoroethane) is being considered as
a replacement for R134a. It has an average GWP of just 130, which in comparison has roughly ten
times less GWP than that of R134a. B.O.Bolagi, M.A.Akintunde, and T.O.Falade investigated
experimentally the performance of three zero ODP HFC refrigerants (R32, R134a and R152a) in a
vapour compression refrigerator and compared the results obtained. The results show that the COP of
R152a was 2.5% higher than that of R134a and 14.7% higher than that of R32 [1] Hydrocarbons are
free from ozone depletion potential and have negligible global warming potential. Wongwise et al
(2006) presented an experimental study on the application of HC mixture to replace HFC -134a in
automotive air-conditioner. They found that mixture of propane / butane / isobutene (50%/40%/10%)
was the best alternative refrigerant to replace HFC-134a having the best performance of all other
mixture being investigated [2]. Wongwise and Chimres presented an experimental study on the
application of a mixture of propane, butane and isobutene to replaceHFC134a in domestic
refrigerators. The results showed that a 60%/40% propane/butane mixture was the most appropriate
alternative refrigerant [3].Dimethyl ether (RE170, DME) makes a better refrigerant than R290 / R600a
blends as it has no temperature glide and doesn’t separate during leakage. It has been extensively
adopted by the aerosol industry as the most cost effective replacement for R134a in propellant
applications [4]. R432A (mixture of DME and propylene) is a good long term ‘drop-in’ environment
friendly alternative refrigerant to replace CFC12 and HFC134a in automobile air-conditioners due to
its excellent thermo dynamic and environment properties. Test results show that the COP of this
refrigerant is up to 21.55% higher than that of R12 in all temperature conditions [5]. R435A (mixture
of DME and R152a) is a good long term ‘drop-in’ environment friendly alternative safe refrigerant to
replace HFC134a in domestic water purifiers due to its excellent thermo dynamic and environmental
properties. Test results show that the energy consumption and discharge temperature was 12.7% and
3.7°C lower than that of HFC 134a [6]. In this study, a general method of selecting `drop-in fluids' will
be presented with a main application in domestic refrigerators charged with CFC12 and HFC134a.
1.1. Selection of Mixtures
For drop in test, In order to use same compressor the Volumetric Cooling Capacity (VRC) of the
mixture should be close to that of R12 and R134a refrigerants. Theoretical and experiment research
shows that the increase in the COP with zeotropic mixtures largely comes from correctly matching the
temperature glides of the refrigerants and air steam [7]. Based on the above criteria, the mixtures of
RE170/R152a and RE170/R600a were selected as the alternatives and environment friendly
refrigerants to the domestic refrigerator working with R12 and R134a respectively.
2. Thermodynamic Cycle Analysis
The cycle analysis was performed for CFC12, HFC134a, DME/R152a and DME/R600a in the
composition of 0.0 to 1.0 mass fractions of DME by CYCLE_D 4.0 Software [9]. All thermodynamic
properties needed for the simulation were computed by REFPROP program [8]. Table 1 lists the
simulation conditions used in the analysis while Fig.1 & 2 illustrates the Volumetric Refrigerating
Capacity (VRC) and COP for CFC12, HFC134a and mixtures DME/R152a and DME/R600a at various
concentrations. Baseline COP and VRC of CFC12 are 2.55 and 751.8 kJ/m
3
, respectively. The
predicted COP of the mixture is 2.61 (+2.3%) higher than that of CFC12 in the composition range of
0.5 mass fraction of DME. The VRC increases linearly as DME is added and at 0.5mass fraction of
DME, the VRC of the mixture becomes very close to that of CFC12. Since the same compressor will
162 A. Baskaran and P. Koshy Mathews
be used in the experiments, the composition of the mixture to be analyzed was fixed to be 0.5 mass
fraction of DME.
Baseline COP and VRC of HFC134a are 2.467and 682.1 kJ/m3, respectively. The predicted
COP of the mixture is 2.621 (+6.24%) higher than that of HFC134a in the composition range of 0.8
mass fraction of DME. The VRC increases linearly as DME is added and at 0.8mass fraction of DME,
the VRC of the mixture becomes very close to that ofHFC134a. Since the same compressor will be
used in the experiments, the composition of the mixture to be analyzed was fixed to be 0.8 mass
fraction of DME.
Table 1: Effect on VRC and COP at various mass fractions of DME under simulation condition of
T
cod
= 45
0
C T
evap
= -25
0
C T
sh
= 20
0
C.
MIX1 MIX2
DME-R152a DME-R600a
MF(DME) VRC COP MF(DME) VRC COP
0.1 705.8 2.593 0.1 427.9 2.564
0.2 726.7 2.593 0.2 477.7 2.569
0.3 739.8 2.596 0.3 524.5 2.575
0.4 745.8 2.602 0.4 567.4 2.581
0.5 745.8 2.608 0.5 605.6 2.589
0.6 741.1 2.615 0.6 637.9 2.599
0.7 732.9 2.622 0.7 662.6 2.61
0.8 722.2 2.63 0.8 679.8 2.621
0.9 709.8 2.638 0.9 690.6 2.633
1.0 696.3 2.646 1 696.3 2.646
Figure 1: VRC of RE170/R152a (mixture1) and RE170/R600a (mixture2) as a function of Mass Fractions of
DME.
0.0 0.2 0.4 0.6 0.8 1.0
400
450
500
550
600
650
700
750
800
850
TC=45
0
C TE=-25
0
C Tsup=20
0
C
VRC of R12 =751.8
VRC of R134a =682.1
VRC of MIX1 =745.8
VRC of MIX2 =679.8
VRC(kJ/m
3
)
Massfraction of DME
R12
R134a
MIX1
MIX2
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators 163
Figure 2: COP of RE170/R152a (mixture1) and RE170/R600a (mixture2) as a function of Mass Fractions of
DME.
0.0 0 .2 0.4 0 .6 0.8 1 .0
1.5
2.0
2.5
3.0
3.5
4.0
TC= 45
0
C TE=-25
0
C Tsup =20
0
C
COP of R12= 2.55
COP of R134a=2.467
COP of MIX1=2.608
COP of MIX2=2.621
COP
Mas s fraction of D M E
R12
R134a
MIX 1
MIX 2
Figure 3: Schematic of sub critical cycle for mixture1
BASE LINE TEST
CONDENSATION TEMPERATURE = 45
0
C
EVAPORATION TEMPERATURE =-25
0
C
DEGREE OF SUPER HEAT = 20
0
C
RE170/R152a
164 A. Baskaran and P. Koshy Mathews
Figure 3.1:
T-S state diagram for subcritical cycle with
mixture1
Figure 3.2:
P-h state diagram for subcritical cycle with
mixture1
Figure 4.0: Schematic of sub critical cycle for mixture2
RE170/R600a
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators 165
Figure 4.1:
T-S state diagram for subcritical cycle with
mixture2
Figure 4.2:
P-h state diagram for subcritical cycle
with mixture2
2.1. Effect of Dimethyl-ether Mass Fraction
The condensation and evaporation pressure decreases with the increase in mass fraction of the DME.
The influence of the DME mass fraction on the performance of domestic refrigerator for mixture 1 and
2 are shown in fig 1 & 2. In mixture 1, it is observed that the VRC increases up to mass fraction 0.5
and decreases further. In mixture 2, the VRC increases with the increase in mass fraction .It is also
observed that COP slightly increases as the mass fraction of dimethyl-ether increases. The main reason
behind this is the rate of change of refrigerating effect which is higher than that of the specific work.
Thus the average COP increases approximately 2.38% and 5.12%when the mass fraction rises for
mixture1 and mixture2 respectively.
3. Method of Analysis
The software CYCLE_D 4.0 vapour compression cycle design program was used for the analysis to
find the performance of the system. The ideal refrigeration cycle is considered with the following
conditions.
System cooling capacity (kW) = 1.00
Compressor isentropic efficiency = 1.00
Compressor volumetric efficiency = 1.00
Electric motor efficiency = 1.00
Pressure drop in the suction line = 0.0
Pressure drop in the discharge line = 0.0
Evaporator: average sat. Temp = -30C to +10C
Condenser: average sat. Temp = 50C
Degree of Super heating = 10C
Degree of Sub cooling = 5C
The analysis of the variation of physical properties and performance parameters such as
evaporation pressure (P
evap
), pressure ratio, isentropic compression work (W), refrigerating effect (RE),
power per ton of refrigeration, volumetric refrigeration capacity (VRC), discharge temperature (T
Dis
),
mass flow rate (MFR) and coefficient of performance (COP) of R12, R134a, mixture1 and mixture2
are investigated in this theoretical study and they are plotted against the evaporating temperature (T
evap
)
as shown in figures from 5 to 14. Table 2 shows the operation results and deviation of alternative
refrigerant mixture 1 & 2 from the values of R12 & R134a respectively.
166 A. Baskaran and P. Koshy Mathews
4. Results and Discussion
The changes in evaporating pressure (P
evap)
and pressure ratio with the evaporation temperature (T
evap
)
were shown in fig 5 and 6 for listed refrigerants. The pressure ratio of refrigerant mixture1 and
mixture2 substituted for R12and R134a was 10.61% higher and 8.07% lower than that of R12 and
R134a respectively as shown in table 2 for the constant condensation and evaporation temperatures of
50C and -10C respectively. Fig 7 and 11 show that the refrigerating effects (RE) increase with
increasing evaporation temperature (T
evap
) while the compressor power (W
comp
) decreases with
increasing T
evap
for the constant condensation temperature of 50C and the evaporation temperature
ranging from -30C to 10C.
The alternative refrigerant mixtures have much higher refrigerating effect and isentropic
compression work than R12 & R134a in Fig 7, 8 and as shown in table 2. The variation of the
performance coefficients (COP) with evaporating temperatures (T
evap
) is illustrated in Fig 9. It is found
that the coefficient of performance (COP) increases as the evaporation temperature (T
evap
) increases for
the constant condensation temperature of 50C and the evaporation temperature ranging from -30C to
10C. The performance coefficients (COP) of the alternating refrigerant mixtures were found to be
higher than that of R12&R134a. The power needed for refrigeration with evaporation temperature
(T
evap
) was shown in Fig 11 and 14. The variation in volumetric refrigeration capacity, discharge
temperature and mass flow rate were illustrated in Fig 10, Fig 12 and Fig 13 in order to verify the
advantages of cycle.
Table 2: Operation on standard vapour-compression cycle using R12, R134a and alternative Refrigerant
mixtures at T
cod
=50
0
C and T
evap
=-10
0
C with superheating 10
0
C and Sub Cooling 5
0
C
Parameters R12 MIX1 Deviation % R134a MIX2 Deviation %
Evaporating pressure (kPa) 218.8 202 -7.68 200.6 186.1 -7.22
Compression Ratio 5.56 6.15 10.61 6.57 6.04 -8.07
Refrigeration Effect (kJ/kg) 109.96 271.12 146.6 137.3 302.3 120.26
Compressor Work (kJ/kg) 32.29 77.95 141.4 41.42 86.61 109.1
Coefficient of Performance(COP) 3.41 3.47 2.14 3.315 3.491 5.31
Volumetric refrigerant capacity (kJm
3
) 1357 1388 2.3 1314 1259 -4.14
Discharge Temperature(°C) 68.5 77.2 12.7 66.3 71.5 7.8
Compressor Power(kW) 0.294 0.287 -2.38 0.302 0.29 -5.3
Mass Flow Rate (kg/sec) 9.09 3.68 -59.44 7.28 3.31 -54.6
Power per ton of refrigeration (kW) 1.03 1.00 -2.140 1.057 1.003 -5.11
Figure 5:
Evaporating Pressure Vs evaporating temperature
-3 0 -20 -1 0 0 1 0
50
100
150
200
250
300
350
400
450
Evaporating pressure(kPa)
Evaporating tem p eratu r e (
0
C)
R 12
R 134 a
M IX1
M IX2
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators 167
Figure 6: Pressure Ratio Vs evaporating temperature
-3 0 - 2 0 - 1 0 0 1 0
2
4
6
8
1 0
1 2
1 4
1 6
Pressure ratio
E v a p o ra t i n g t e m p e r a t u r e (
0
C )
R 1 2
R 1 3 4a
M I X 1
M I X 2
Figure 7: Refrigerating effect Vs evaporating temperature
-3 0 -2 0 -1 0 0 1 0
1 0 0
1 2 0
1 4 0
1 6 0
1 8 0
2 0 0
2 2 0
2 4 0
2 6 0
2 8 0
3 0 0
3 2 0
Refrigerating effect(kJ/kg)
E va p or at in g t em p e r at u re (
0
C )
R 1 2
R 1 34 a
M I X 1
M I X 2
Figure 8: Compression Work Vs evaporating temperature
-3 0 -2 0 - 1 0 0 1 0
2 0
4 0
6 0
8 0
1 0 0
1 2 0
1 4 0
Compressor work(kJ/kg)
E va po ra tin g te m pe ra tu r e (
0
C )
R 1 2
R 1 3 4a
M IX 1
M IX 2
168 A. Baskaran and P. Koshy Mathews
Figure 9: C.O.P Vs evaporating temperature
-3 0 - 2 0 -1 0 0 10
1. 5
2. 0
2. 5
3. 0
3. 5
4. 0
4. 5
5. 0
5. 5
6. 0
6. 5
COP
E vap o ra tin g t e m pe rat u r e (
0
C )
R 12
R 134 a
M IX1
M IX2
Figure 10: Volumetric refrigerating capacity Vs evaporating temperature
-3 0 - 2 0 -1 0 0 1 0
50 0
10 0 0
15 0 0
20 0 0
25 0 0
30 0 0
VRC(kJ/m
3
)
Eva po rat ing t e m pera t u re (
0
C )
R 12
R 134 a
M IX1
M IX2
Figure 11: Compressor Power Vs evaporating temperature
-3 0 -2 0 - 1 0 0 10
0 .1 5
0 .2 0
0 .2 5
0 .3 0
0 .3 5
0 .4 0
0 .4 5
0 .5 0
Compressor power(kW)
E va p o r a ti n g te m p e r a tu re (
0
C )
R 1 2
R 1 34 a
M I X 1
M I X 2
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators 169
Figure 12: Discharge temperature Vs evaporating temperature
-3 0 - 20 -1 0 0 10
62
64
66
68
70
72
74
76
78
80
82
84
86
88
90
Discharge temperature(
0
C)
Evapo ratin g te mperature (
0
C)
R 1 2
R 1 3 4 a
M IX1
M IX2
Figure 13: Mass flow rate Vs evaporating temperature
-30 - 20 -1 0 0 10
3
4
5
6
7
8
9
10
MFR*10
-3
(kg/sec)
Evaporating temperature (
0
C)
R12
R134a
MIX1
MIX2
170 A. Baskaran and P. Koshy Mathews
Figure 14: Power per ton of refrigeration Vs evaporating Temperature
-30 -20 -10 0 10
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
P/TR(kW)
Evaporating temperature (
0
C)
R12
R134a
MIX1
MIX2
4.1. Comparison among the Investigated Refrigerants
The refrigeration effect of mixture RE170/R152a is 142% to 152% higher than that of R12 at (-30°C to
10°C) evaporator temperature and 50°C condenser temperature. The refrigeration effect of mixture
RE170/R600a is 116% to 124% higher than that of R134a at (-30°C to 10°C) evaporator temperature
and 50°C condenser temperature. The average pressure ratio for the mixture RE170/R600a is nearly(
5.03% to 11.97% ) lower than that of R134a.Specific work of the mixture RE170/R152a is 144% to
138.9% higher than that of R12 and the mixture RE170/R600a is 109.06% to109.62% higher than that
of R134a at (-30°C to 10°C) evaporator temperature and 50°C condenser temperature. The COP of the
alternative refrigerants is higher than that of R12 and R134a by about 1.33% to 3.20% and 3.47% to
7.56% respectively over the range of operating conditions. The Compressor power for the alternative
refrigerants is lower than that of R12 and R134a by about 1.2% to 3.20% and 2.96% to 7.17%
respectively over the range of operating conditions. The mass flow rate of the alternative refrigerants is
lower than that of R12 and R134a by about 58.71% to 60.31% and 53.89% to 55.52% respectively
over the range of operating conditions
5. Conclusions
In the present study, a theoretical investigation was performed to evaluate the performance
characteristics of the domestic refrigerator working with R12, R134a, RE170 (50%)/R152a (50%)
Mixture1, RE170 (80%)/R600a (20%) Mixture2. The volumetric cooling capacities of R12 and
alternative refrigerant mixture1 are same over the considered range of operating conditions. Similarly
the volumetric cooling capacities of R134a and alternative refrigerant mixture2 are same over the
considered range of operating conditions. So it was concluded that mixture1 and mixture2 are drop in
replacement for R12 and R134a respectively. The identified alternatives offer desirable environmental
requirements, that is zero ozone depletion potential (ODP) and lower global warming potential (GWP).
Comparative Study of Environment Friendly Alternatives to
R12 and R134a in Domestic Refrigerators 171
References
[1] Bolagi, B.O., Akintunde, M.A., and Falade, T.O., 2011. Comparative analysis of performance
of three ozone friends HFC refrigerants in a vapour Compression refrigerator. J. Sustainable
energy and environ. 2, 61-64.
[2] Choedaeseong, Dangsoo Jung, 2010. Performance of R435A on refrigeration system of
domestic water purifiers. Int. J. SAREK. 11, 366 - 371.
[3] CYCLE_D: Vapour compression cycle design NIST Standard reference data base 23 -version
4.0 Gaithersburg (MD): National institute of standards and technology.
[4] In-cheol Baek, Ki–Jung Park, Yun–Bo Shim, Dongsoo Jung, 2007. Performance of alternative
refrigerants for R12 and R134a in automobile air conditioners. Korean J. Air conditioning and
refrigeration engineering. 19, 403 - 410.
[5] Nicholas Cox, 2010. Developments and opportunities using hydrocarbons refrigerant blends.
Presented to Transforming Technologies Conference, London. www.earth care products.co.UK
[6] REFPROP: Reference fluid thermodynamic and transport properties. NIST Standard reference
data base 23-version 7.1 Gaithersburg (MD): National institute of standards and technology.
[7] Srinivas, P., Dr. Raju, A.V.S.R., Dr. Babu, P.S., 2011. Comparative assessment of environment
friendly alternatives to R12 and R134a in domestic refrigerators. IE (I) J. MC. 92, 8-13.
[8] Wongwises, S., Kamboon, A., Orachon, B., 2005. Experimental Investigation of Hydrocarbon
Mixture to replace HFC-134a in an automotive air conditioning system. Energy convers. And
management. 46, 1644 -1649.
[9] Wongwises, S., Chimres, N., 2005. Experimental study of hydrocarbon mixture to replace
HFC134a in a domestic refrigerator. Energy convers. And management. 46, 85-100.
Nomenclature
GWP Global warming potential
HCFCs Hydro chlorofluorocarbons
ODP Ozone depletion potential
RE Refrigerating effect, kJ Kg
-1
MFR Mass flow rate, kgs
-1
W isentropic compression
Work kJ kg
-1
VRC Volumetric refrigerating capacity, kJm
-3
MF Mass Fractions
DME Dimethyl Ether
Subscripts
cod Condensing/Condenser
evap evaporating/evaporater
comp compressor
dis discharge
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This communication deals with the exergetic analysis of a vapour compression refrigeration system with selected refrigerants. The various parameters computed are COP, exergetic efficiency and EDR in the system. Effects of condenser temperature, evaporator temperature and sub-cooling of condenser outlet, super-heating of evaporator outlet and effectiveness of vapour liquid heat exchanger are also computed and discussed. In this study, it was found that R429A has the better performance in all respect, whereas refrigerant mixture has lower performance.
... Dnyaneshwar M. A. et al. [5] worked on exploring of environmental friendly alternative refrigerants for the R-12, R-22 and R134a for low GWP and negligible ODP, and a better coefficient of performance (COP). Baskaran and Mathews [6] assessed theoretically and found the possibility of using refrigerant blends of RE170, R152a and R600a as alternatives to the refrigerants like R12 and R134a. Jagnarayan R. et al. [7] experimentally investigated replacement of R134a and Agrawal N. et al. [8] analyzed system performance of existed R134a domestic refrigerator with propane/isobutane (50/50%) zeotropic blend was measured as a drop-in substitute. ...
Article
R12 had been widely used as a refrigerant for many decades but it has high ozone depletion potential and global warming potential hence it was replaced by R134a which has zero ozone depletion potential and very less global warming potential compared to R12, and also the performance of R134a is much better in vapour compression refrigeration system. Nowadays, R134a is being widely used as a refrigerant in domestic and industrial applications but to optimize the system performance and further protect our environment from global warming R134a should be replaced. This research work determines possibility of a case that can replace R134a. For this purpose, R600a and hydrocarbon (blend of R290 and R600a) have been used as refrigerants separately. These refrigerants have zero ozone depletion potential and almost negligible global warming potential. The performances of three refrigerants (R134a, R600a and hydrocarbon blend) have been analyzed on vapour compression refrigeration system at different thermostat positions (i.e. different suction and discharge pressures). Further, Carnot COPs and second law efficiencies of these three refrigerants have also been calculated to find best operating conditions for the system. This experiment research work has been concluded as; maximum coefficient of performance (i.e. 3.33) and second law efficiency (i.e. 58.94%) are found with R600a at 12.9 psi suction and 99.7 psi discharge pressures but minimum coefficient of performance (i.e. 1.99) and second law efficiency (i.e. 43.83%) are obtained with R134a experimentally. So, R600a has been recommended as alternative refrigerant for vapour compression refrigeration systems.
... Baskaran et al. [10][11][12][13][14][15][16][17][18] analyzed the performance of a vapor compression refrigeration system with DME and its blends. The results were compared with R134a as a possible alternative refrigerant. ...
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In this study, the first and second law analysis of Dimethyl ether (DME) and its blend refrigerants (R429A, R435A, R 510A) is presented as an alternatives to R134a. A computational model, developed in cycle_D software, is employed for comparing the performance of these refrigerants in vapour compression refrigeration cycle. The thermodynamic properties of the DME and its blend refrigerants are computed using Refprop version 9.0. The parameters computed are volumetric refrigerating capacity, compressor discharge temperature, Co efficient of performance and exergy efficiency in system. The results indicate that VRC, COP and exergy efficiency for R134a are lower in comparison with R429A, R435A, R510A.
... Baskaran.et al. [8][9][10][11][12][13][14] reported the performance of a vapor compression refrigeration system with Di methyl ether and its blends. The results showed that the Di methyl ether and its blends have better performance when compared with R134a. ...
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¬This study deals with the Thermodynamic evaluation of the use of Di-methyl ether refrigerants in household refrigeration systems which utilize R134a as a working fluid. A theoretical computational analysis was developed for R134a, Di-methyl ether (RE170) and the selected mixtures (R429A, R435A and R510A) in the standard refrigeration cycle ASHRAE, using the REFPROP 9.0 software. The results of computational simulations between the fluids were compared to find the evidence of the best alternative for R134a. In this sense, it is observed that the Di methyl ether reduced the levels of pressure on the condenser and evaporator. It also reduces the mass to be charged in the system. The use of these refrigerants reduces mass flow rate and increases refrigerating capacity of the system.
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In this paper, the performances of three ozone-friendly Hydrofluorocarbon (HFC) refrigerants (R32, R134a and R152a) in a vapour compression refrigeration system were investigated experimentally and compared. The results obtained showed that R32 yielded undesirable characteristics, such as high pressure and low Coefficient of Performance (COP). Comparison among the investigated refrigerants confirmed that R152a and R134a have approximately the same performance, but the best performance was obtained from the used of R152a in the system. As a result, R152a could be used as a drop-in replacement for R134a in vapour compression refrigeration system. The COP of R152a obtained was higher than those of R134a and R32 by 2.5 % and 14.7 % respectively. Also, R152a offers the best desirable environmental requirements; zero Ozone Depleting Potential (ODP) and very low Global Warming Potential (GWP).
Article
In the present study, the possibility of using blends of R134a and hydrocarbons, ie, R290, R1270, R600a as alternatives to R12 and R134a in domestic refrigerators has been assessed theoretically. Due to the fact that R-12 is having a ODP value of '1' and R-134 a is not miscible in mineral oil, polyol ester (POE) based synthetic oils are recommended. These oils are highly hygroscopic and have inherent service issues when used in appliances. The performance characteristics of domestic refrigerators were predicted over a wide range of evaporation temperatures(-30°c to-10°c) and condensation temperatures (30°c to 50°c) for various working fluids, which include R12, R134a, R290, R1270, R600a, ternary mixtures R134a/R290/R600a and R134a/R1270/R600a mixture with various isobutane(R600a) mass fractions. The assessment was carried out by comparing parameters, such as, pressure ratio, volumetric cooling capacity (VCC), coefficient of performance (COP), specific work and cooling capacity. The investigation reveals that pure hydrocarbon refrigerants are not the appropriate replacement for R12 and R134a due to its mismatch in volumetric cooling capacity (VCC), further it requires change in compressor specification. The present study indicate a drop in replacement for R-12 with the ternary mixtures (R134a/R290/R600a & R134a/R1270/R600a) with the mass fractions of 50%/12%/38%.Similarly, R-134a can be replaced with the same ternary mixtures with different mass fractions of 50%/4%/46%.
Article
This work presents an experimental study on the application of hydrocarbon mixtures to replace HFC-134a in a domestic refrigerator. The hydrocarbons investigated are propane (R290), butane (R600) and isobutane (R600a). A refrigerator designed to work with HFC-134a with a gross capacity of 239 l is used in the experiment. The consumed energy, compressor power and refrigerant temperature and pressure at the inlet and outlet of the compressor are recorded and analysed as well as the distributions of temperature at various positions in the refrigerator. The refrigerant mixtures used are divided into three groups: the mixture of three hydrocarbons, the mixture of two hydrocarbons and the mixture of two hydrocarbons and HFC-134a. The experiments are conducted with the refrigerants under the same no load condition at a surrounding temperature of 25 °C. The results show that propane/butane 60%/40% is the most appropriate alternative refrigerant to HFC-134a.
Article
This paper presents an experimental study on the application of hydrocarbon mixtures to replace HFC-134a in automotive air conditioners. The hydrocarbons investigated are propane (R290), butane (R600) and isobutane (R600a). The measured data are obtained from an automotive air conditioning test facility utilizing HFC-134a as the refrigerant. The air conditioner, with a capacity of 3.5 kW driven by a Diesel engine, is charged and tested with four different ratios of hydrocarbon mixtures. The experiments are conducted at the same surrounding conditions. The temperature and pressure of the refrigerant at every major position in the refrigerant loop, the temperature, flow rate and humidity of air, torque and engine speed are recorded and analyzed. The parameters investigated are the refrigeration capacity, the compressor power and the coefficient of performance (COP). The results show that propane/butane/isobutane: 50%/40%/10% is the most appropriate alternative refrigerant to replace HFC-134a, having the best performance of all the hydrocarbon mixtures investigated.
Performance of R435A on refrigeration system of domestic water purifiers
  • Dangsoo Choedaeseong
  • Jung
Choedaeseong, Dangsoo Jung, 2010. Performance of R435A on refrigeration system of domestic water purifiers. Int. J. SAREK. 11, 366 -371.
Performance of alternative refrigerants for R12 and R134a in automobile air conditioners
  • Ki-Jung In-Cheol Baek
  • Yun-Bo Park
  • Dongsoo Shim
  • Jung
In-cheol Baek, Ki-Jung Park, Yun-Bo Shim, Dongsoo Jung, 2007. Performance of alternative refrigerants for R12 and R134a in automobile air conditioners. Korean J. Air conditioning and refrigeration engineering. 19, 403 -410.
Developments and opportunities using hydrocarbons refrigerant blends. Presented to Transforming Technologies Conference, London. www.earth care products
  • Nicholas Cox
Nicholas Cox, 2010. Developments and opportunities using hydrocarbons refrigerant blends. Presented to Transforming Technologies Conference, London. www.earth care products.co.UK