Abstract
In today’s world, more importance is given to use clean,
green and efficient utilization of energy resources. Therefore the eco-friendly
refrigerants are used for reducing global warming and ozone depletion. These
systems are working on vapour compression refrigeration
cycles. Furthermore, it is necessary to use eco-friendly cascade
refrigeration technology. In order to appreciate the three and four cascade
refrigeration cycles are used for ultra-low temperature applications.
In
this paper, we proposed sixteen new multi cascaded vapour compression
refrigeration systems consisting of vapour compression cycle in which cascaded the evaporator of using HFO refrigerant is coupled with the cascaded condenser
of medium temperature vapour compression refrigeration cycle with
temperature overlapping (MTC approach of 10oC) using another HFO
refrigerant. Similarly cascaded evaporator (of temperature up to -70oC)
is again cascaded with the condenser of medium/intermediate
temperature cycle with temperature overlapping (MTC approach of 10oC).
The cascaded intermediate temperature evaporator of -70oC was
again cascaded with ultra-low cascaded condenser using low GWP of HFO
refrigerants with temperature overlapping (LTC approach of 10oC)
in vapour compression cycle to produce cooling at evaporator temperature
of -140oC and thermodynamic performances
are compared with R134a which has high GWP. Numerical computations were
carried out by using HFO refrigerants and found that three-stage cascade
vapour compression refrigeration system using R1234ze(Z) in the
high-temperature cycle between the temperature range of (55oC to 0oC)
and R1233zd(E)in medium temperature cycle between the temperature range of (0oC
to -70oC) and R1225ye(Z) in a low-temperature cycle between the
temperature range of (-70oC to -140oC) is the optimal system gives better thermodynamic performances.
1.
Introduction
Refrigeration is accountable for 20% of global energy
consumption. Furthermore, the refrigeration process is associated with a series
of environmental problems such as the ozone layer depletion and the global
warming phenomenon due to the destructive refrigerants. Therefore, there is a
need for launching a cascade refrigeration system with high efficiency and
environmentally-friendly refrigerants. There are many ultra-low
temperature cascade refrigeration systems in use today with evaporator
temperatures from -50oC to -80oC is used biomedical
applications.
Single-stage vapour compression refrigeration system is not
capable to achieve such low temperatures with the use of a reciprocating
compressor, due to a very high-pressure ratio across the compressor. Higher
pressure ratios and volumetric efficiency give you an idea about higher
condenser temperatures and for this reason, the capacity of the reciprocating
compressor drastically reduces. Though multistage or screw compressors can
assist in excluding the use of single refrigerant at low temperature is limited
by solidification temperature of the refrigerant, extremely low pressures in
the evaporator, large suction volumes in the evaporator for a high boiling
point refrigerant and high condenser pressure for a low boiling refrigerant.
This necessitates integrating for other viable options to partially or fully
overcome the above shortcomings. The characteristics of any refrigerant to
exhibit the best performance, when operating in a certain range of temperature
and pressure, provide cascade refrigeration systems with an edge over
single-stage and multistage refrigeration systems for low-temperature
applications. Cascade refrigeration systems employ a series of single-stage
units which are thermally coupled with evaporator/condenser cascades.
For ultra-low temperature applications required
refrigeration in the range of - 80°C to -150°C. Three stages cascade
refrigeration cycles are commonly used in the liquefaction of natural gas,
which consists basically of hydrocarbons of the paraffin series, of which
methane has the lowest boiling point at atmospheric pressure.
According to the European Parliament Directive 517/2014 [1],
the use of refrigerants with high global warming potential (GWP) has to be
abridged. A general limit in the GWP can be selected at 150, especially for the
domestic refrigeration systems and so the use of refrigerants with lower GWP
has to be used in the new systems or to replace the present refrigerants.
Vapour compression refrigeration systems using R152a is
found to be the most efficient refrigerant compared with other HFC and
hydrocarbon refrigerants. Although R134a is a widely used refrigerant due
to its commercial availability, similar properties to R152a, with ODP value,
excellent thermal stability, nontoxic and non-flammability etc have high GWP
value around 1430. The only issue is to reduce global warming by using low
GWP refrigerants. The thermodynamic performance comparison with using
R152a and R245fa and R32 with R134a not many differences and can replace R134a
in the near future. Although the refrigerants R152a and R245fa are highly effective for the cooling vapour compression cycles. These refrigerants are non-toxic and have a higher GWP than HFC refrigerants. Therefore HFC refrigerants are a reliable choice for future cooling systems.
2.
Use of HFO
refrigerants for replacing HFC refrigerants
In recent years, the fourth generation Hydro-fluoro-olefins
(HFOs)-R1234yf and R1234ze are being considered as an alternative to R134a. A
number of studies have been carried out using HFO 1234yf. The European Union
(EU) regulation is phasing out the current generation HFCs like R134a due to
its high GWP and environmental consequences. The European Union (EU) regulation
is phasing out the current generation HFCs like R134a due to its high GWP and
environmental consequences. A number of studies have been carried out using
R1234yf and R1234ze(E) [2, 3] and found that The R1234ze(Z) gives better
thermodynamic performances than R1234ze(E) and R1243zf. The thermodynamic
performance of R1224yd (Z) and HFO-1336mzz(Z) is nearly similar and higher than
R1234ze(E) but lower than R1224yd(Z). However, R1234yf gives the lowest
thermodynamic performances.
Mishra [2] analyzed the hydro-fluoro-olefines
(HFO) and hydro chloro-fluoro-olefines (HCFO) used in vapour compression
refrigeration systems. The HFO R1234yf and R1234ze (E), as well as the HCFO
R1233zd(E) and R1224yd(Z), are especially promising low-GWP alternatives to the
HFC R134a and R245fa.For instance, the German Environment Agency intends to
prohibit the application of R1233zd(E), due to its ODP of 0.00024. However,
R1233zd(E) has several favorable aspects, such as a very low GWP and no
flammability and toxicity (safety classification of A1). This proves, that the
very small ODP by R1233zd(E) and R1224yd lead to no significant increase of the
external costs. Thus, a general prohibition of potentially promising refrigerants
with a very small ODP appears not be justifiable based on the presented
results. The electrical powers are lower by using HCFO-1233zd-E as compared to
R134a As a conclusion, it can be stated, that both novel fluids R1233zd(E) and
R1224yd(Z) are suitable for the drop-in replacement of R245fa in refrigeration
systems. However, the results show, that the compatibility of R1233zd(E) and
R1224yd(Z) is compared to replace R245fa and R134a , it is found that when
R1233zd(E)is used, for finding the system performances, the highest power
output is still obtained with the high-GWP fluid R245fa and R134a which is 7%
to 9% The exergy of fuel with R245fa is 0.40% higher compared to R1233zd(E) and
8% higher compared to R1224yd(Z). In terms of thermal efficiency of the ORC
system, R1233zd(E) leads to approximately 2% higher values compared to R245fa.
In contrast to that, the thermal efficiency of R245fa and R1224yd(Z) is equal
over a wide range of operation conditions. 1.2 HFO-1336mzz(E) and R1336mzz(Z)
R1336mzz(Z) (also referred to as HFO1336mzz(Z)) provides approximate
thermodynamic property data for cis-1,1,1,4,4,4- Hexafluoro-2-butene, MW
164.056 gm/mole, CAS# 692-49-9). The fundamentals of choosing a good working
refrigerant are based on system optimization to maximize the thermodynamic
performance characteristics in terms of first and second law efficiencies,
these novel HFOs are being developed, like HFO1336mzz(E) and R1336mzz(Z), to
meet the more stringent regulations of low GWP and no ODP and they demonstrate
the known characteristics of a good working fluids stability, compatibility,
favorable toxicity and performance even at high temperatures. The
HFO-1336mzz(E) has a 7.5oC boiling point, the critical temperature
of 137.6oC and critical pressure of 3.15 MPa. Whereas R-1336mzz(Z)
has a slightly higher boiling point of 33.4oC, critical temperature of 171.3oC
and lower critical pressure of 2.90 MPa. The compressor efficiency, superheat,
sub cooling and lift temperatures were fixed variables is this calculation, the
condensing temperatures were adjusted so higher temperature effects could be
evaluated for each working fluid. HFO1336mzz isomers (E and Z) and had the
excellent first law efficiency (COPs) amongst than the HFC Refrigerants (such
as R134a, R410a, R404a, R407c, R507a, R125a) but lower than R245fa due to and
power required to run compressors are 8.63% higher than R245fa. Mishra et
al. [2] performed exergy analysis on a vapour compression
refrigeration systems using liquid vapour heat exchanger and several HFO
refrigerants (i.e. R1234yf, R1234ze(Z) R1234ze(E), R1243zf, R1224yd(z),
R1225ye(z) and HFO-1336mzz(Z)) for replacing R134a refrigerants. The HFO
refrigerants were good alternatives to R134a regarding their
environment-friendly properties. The ecofriendly refrigerants such as R134a,
R1234yf, and R1234ze(E) are pure substances. The HFO (hydro-fluoro-olefin) are
going to be our future refrigerants with low ozone depletion potential (ODP)
and low global warming potential (GWP). The basic properties of new future HFO
refrigerants expected as R134a and R32 alternatives which are presently used in
refrigerators. R1243zf is probably to be a good alternative with its
flammability, which is A2 category for replacing R134a [3]. Attila
Gencer [4] were theoretically evaluated the thermodynamic behaviour in terms of energy
parameters (i.e., cooling capacity and COP) for three different vapour
compression refrigeration systems (i.e. Basic cycle, basic cycle with
liquid-to-suction heat exchanger and two-stage cascade cycle) and compared
exergetic efficiency using low GWP alternative refrigerants (i.e. R1234yf,
R1234ze(E), R513A, R445A and R450A) for replacing R134a. The comparison
of the energy parameters for two different evaporation temperatures (-30°C and
0°C) and two condensing temperatures (40°C and 55°C) was carried out and
numerical results show that R450A which almost has the same COP values as
R134a comes into prominence with 58% lower GWP value compared to R134a.
They suggested that R445A gives highest exergetic efficiency with liquid shell
heat exchanger and also concluded that the studied refrigeration cycles, a
system for providing a better effect in terms of COP for the considered
refrigerants and temperature cases as well as assumed system parameters. It is
found that system with liquid shell heat exchanger gives better effect in terms
of COP for the considered refrigerants and temperature cases as well as assumed
system parameters.
Sanchez et al. [5] compared five low GWP
refrigerants R152a, R1234yf, R1234ze, R290 and R600a for the replacement of
R134a using hermetic the compressor in the experimental test rig and found that
the R1234yf can be considered a suitable drop-in alternative to R134a by
considering the energy consumption and the cooling refrigerating capacity of
the facility.
Mota-Babiloni, A [6]. Evaluated energy performances of
two low-GWP refrigerants such as R1234yf and R1234ze(E), as drop-in
replacements for R134a, and conducted various tests in the vapour compression
system by combining different values of evaporation and condensation
temperature, and without/with the adoption of an internal heat exchanger.
Thermodynamic parameters such as volumetric efficiency, cooling capacity and
COP are analyzed by taking R134a as a baseline and found without internal heat
exchanger the average volumetric efficiency for R1234yf and R1234ze is 4% and
5% lower as compared with R134a. Also found that the cooling capacity with
R1234yf and R1234ze is reduced, with an average difference of 9% and 30%
without an internal heat exchanger, respectively. Similarly, first law
efficiency (COP) values are about 7% lower for R1234ye and 6% are lower for
R1234ze than using R134a. Although, the use of an internal heat exchanger
reduces the COP differences for both replacements and energy performance
evaluation of two low-GWP refrigerants, R1234yf and R1234ze(E), as drop-in
replacements for R134a.
Mota-Babiloni, A., Novarro-Esbri J., Barragan-Cervera,
A., Moles, F., Peris, B. [7] performed an experimental investigation on the
direct use of R1234yf in a system operating with R134a and found that the
reduction in the cooling capacity of 6% to 13% approximately using R1234yf
instead of R134a. Mota-Babiloni et al. [8] experimentally studied R513A as a
substitute for R134a. They found that both cooling capacity and COP values
of R513A were better than that of R134a at different evaporation and condenser
temperatures.
Yang et al. [9] found that the use of R152a in a cascade
system with CO2 is more efficient than the use of R134a/CO2 and
R124/CO2 cascade systems. Bolaji [10] studied a
simple refrigeration system with R152a, R134a and R32. It is found that the use
of R152a leads to 8.5% higher coefficient of performance (COP) than R134a,
while R32 is the less efficient refrigerant. Cabello et al. [11] carried out an experimental comparison of a cascade
refrigeration system working with the refrigerant pairs R134a/R744 and
R152a/R744and found that the replacement of R134a with R152a is technically and
energetically feasible.
Above investigators have not carried out the performance
evaluation for low-temperature applications in cryogenics and the effect of
performance parameters using HFO-refrigerants in intermediate temperature
circuit and other HFO-refrigerants such as HFO-1336mzz(z) and R1225ye( in
low-temperature circuit. Therefore, this paper mainly deals with performance
evaluations at -140oC used for cryogenics applications and
comparison at -70oC evaporator the temperature in the
low-temperature circuit using HFO refrigerants in the intermediate/medium
temperature circuit.
3.
Results and
Discussion
The
following sixteen cascade vapour compression system for low temperature
applications have been considered for
numerical computations
System-1: Three stage cascade vapour compression system for low temperature
applications using R-1234ze(Z) in high
temperature cycle (HTC), R1233zd(E) in medium
temperature cycle (MTC) and HFO-1336mzz(Z)in in low temperature cycle (LTC).
System-2: Three stage cascade vapour
compression system for low temperature applications using R-1234ze(Z) in HTC,
R1233zd(E) in MTC and R1225ye(Z) in LTC.
System-3: Three stage cascade vapour
compression system for low temperature applications using R-1234ze(Z) in HTC,
HFO-1336mzz(Z) in MTC and R1225ye(Z)in LTC.
System-4: Three stage cascade vapour
compression system for low temperature applications using R-1234ze(Z) in HTC,
R1225ye(Z) in MTC and HFO-1336mzz(Z) in LTC.
System-5: Three stage cascade vapour compression system for low temperature
applications using R-1234ze(E) in HTC,
R1233zd(E) MTC and HFO-1336mzz(Z)in in low
LTC.
System-6: Three stage cascade vapour
compression system for low temperature applications using R-1234ze(E) in HTC,
R1233zd(E) in MTC and R1225ye(Z) in LTC.
System-7: Three stage cascade vapour
compression system for low temperature applications using R-1234ze(E) in HTC,
HFO-1336mzz(Z) in MTC and R1225ye(Z) in LTC.
System-8: Three stage cascade vapour
compression system for low temperature applications using R-1234ze(E) in HTC,
R1225ye(Z) in MTC and HFO-1336mzz(Z) in LTC.
System-9: Three stage cascade vapour compression system for low temperature
applications using R-1243zf in HTC, HFO-1336mzz(Z) in MTC and R1225ye(Z)in LTC.
System-10: Three stage cascade vapour
compression system for low temperature applications using R-1243zf in HTC,
R1225ye(Z) in MTC and HFO-1336mzz(Z) in LTC.
System-11: Three stage cascade vapour
compression system for low temperature applications using R-1243zf in HTC,
R1233zd(E) in MTC and R1225ye(Z) in LTC.
System-12: Three stage cascade vapour
compression system for low temperature applications using R-1243zf in HTC,
R1233zd(E) in MTC and HFO-1336mzz(Z) in LTC.
System-13: Three stage cascade vapour compression system for low temperature
applications using R-1224 yd(Z) in HTC, HFO-1336mzz(Z) in MTC and R1225ye(Z)in
LTC.
System-14: Three stage cascade vapour compression system for low temperature
applications using R-1224 yd(Z) in HTC, R1225ye(Z) in MTC and HFO-1336mzz(Z) in
LTC.
System-15: Three stage cascade vapour compression system for low temperature
applications using R1233zd(E) in HTC, HFO-1336mzz(Z)) in MTC and R1225ye(Z) in
LTC.
System-16: Three stage cascade vapour compression system for low temperature
applications using R1233zd(E) in HTC, R1225ye(Z) in MTC and HFO-1336mzz(Z) in
LTC.
The input data for each three stages
vapour compression refrigeration cascaded systems are given below:
Three stages cascade vapour compression
refrigeration systems using ecofriendly refrigerants has been considered with
following input conditions.
·
Temperature
of High temperature condenser = 55oC
·
Refrigerant
used High temperature cycle =HFO refrigerant
·
Temperature
of High temperature evaporator = 0oC
·
Isentropic
efficiency of high temperature compressor
= 80%
·
Refrigerant
used low temperature cycle = HFO refrigerant
·
Temperature
of low temperature evaporator = - 70oC
·
Isentropic
efficiency of medium temperature
compressor = 80%
·
Refrigerant
used low temperature cycle = HFO refrigerant
·
Temperature
of low temperature evaporator = - 140oC
·
Isentropic
efficiency of low temperature compressor
= 80%
·
Cooling
Load on low temperature evaporator = 10x3.51 kW.
§ Temperature
overlapping between low temperature cascade condenser and High temperature
evaporator = 10 oC
§ Temperature
overlapping between low temperature
cascade condenser and medium
temperature evaporator = 10 oC
Table-1 shows the thermodynamic performances of four systems in which
ecofriendly refrigerant using R-1234ze(E) in the high
temperature cycle at 55oC of condenser temperature systems
(system-1 to system-4) with 10 oC temperature overlapping (approach) and found that System-2:containing R-1234ze(Z) in high temperature cycle (HTC) of condenser temperature of 55oC and 0oC
of evaporator temperature and R1233zd(E) in medium temperature cycle (MTC)
at evaporator temperature of -70oC
and R1225ye(Z)in ultralow evaporator temperature in low temperature
cycle (LTC ) gives best first and second law performances as compared to system-3 using R-1234ze(E) in high temperature cycle HTC, and HFO1336mzz(Z) in medium temperature cycle (MTC) and R1225ye(Z)in low
temperature cycle( LTC). However lowest
performances was observed in system-4 using R-1234ze(E) in high temperature cycle HTC
and R1225ye(Z) in medium temperature
cycle MTC and HFO-1336mzz(Z) in ultra-low
temperature cycle (LTC). The power
required to run both compressors in whole cascade system is lowest in
system-15. The second law performance is
also high in system-2.
Table-2 shows the thermodynamic performances of four systems in which
ecofriendly refrigerant using R-1234ze(E) in the high
temperature cycle at 55oC of condenser temperature systems
(system-5 to system-8) with 10 oC temperature overlapping (approach) and found that System-6:containing R-1234ze(E) in high temperature cycle (HTC) of condenser temperature of 55oC and 0oC
of evaporator temperature and R1233zd(E) in medium temperature cycle (MTC)
at evaporator temperature of -70oC
and R1225ye(Z)in ultralow evaporator temperature in low temperature
cycle (LTC ) gives best first and second law performances as compared to system-7 using R-1234ze(E) in high temperature cycle HTC, and HFO1336mzz(Z) in medium temperature cycle (MTC) and R1225ye(Z)in low
temperature cycle( LTC). However lowest
performances was observed in system-8 using R-1234ze(E) in high temperature cycle HTC
and R1225ye(Z) in medium temperature
cycle MTC and HFO-1336mzz(Z) in ultra-low
temperature cycle (LTC). The power
required to run both compressors in whole cascade system is lowest in
system-15. The second law performance is
also high in system-6.
Table-3 shows the thermodynamic performances of four systems in which
ecofriendly refrigerant using R1243zf in the high temperature cycle at 55oC of
condenser temperature in four systems (system-9 and system-12) with 10 oC temperature overlapping (approach) and found that System-11:containing R-1243zf in high temperature cycle (HTC) of
condenser temperature of 55oC
and 0oC of evaporator temperature
and R1233zd(E) in medium
temperature cycle (MTC) at evaporator temperature of -70oC and R1225ye(Z)in ultralow evaporator
temperature in low temperature cycle (LTC ) gives best first and second law
performances as compared to system-9 using R-1243zf in high
temperature cycle HTC, and
HFO1336mzz(Z) in medium
temperature cycle (MTC) and R1225ye(Z)in low temperature cycle( LTC). However lowest performances was observed in
system-10 using R-1243zf in high
temperature cycle HTC and R1225ye(Z) in
medium temperature cycle MTC and HFO-1336mzz(Z)
in ultra-low temperature cycle (LTC). The power required to run both compressors in whole cascade system is
lowest in system-15. The second law
performance is also high in system-11. Table-4 shows the thermodynamic
performances of four systems in which ecofriendly refrigerant R-1224 yd(Z in the high temperature cycle at
55oC of evaporator in two systems (system-13 and system-14) and R1233zd(E)
in the high temperature cycle at 55oC of
evaporator in two systems (system-15 and system-16) with 10 oC temperature overlapping (approach) and found that System-15:containing R1233zd(E) in high temperature cycle (HTC) of
condenser temperature of 55oC
and 0oC of evaporator temperature
and HFO-1336mzz(Z) in MTC at
evaporator temperature of -70oC
and R1225ye(Z)in ultralow evaporator temperature in low temperature
cycle (LTC ) gives best first and second law performances.to system-13 using R-1224 yd(Z) in
high temperature cycle HTC, and
HFO1336mzz(Z) in medium
temperature cycle (MTC) and R1225ye(Z)in low temperature cycle( LTC). However lowest performances was observed in
system-14 using System-14: R-1224 yd(Z) in high temperature cycle HTC
and R1225ye(Z) in medium temperature cycle
MTC and HFO-1336mzz(Z) in ultra-low
temperature cycle (LTC). The power
required to run both compressors in whole cascade system is lowest in
system-15. The second law performance is
also high in system-15,
Table-5 shows the best system to be
considered based on maximum first law efficiency (i.e. System COP_Cascade ),
maximum second law efficiency (i.e.
System Exergetic Efficiency Cascade),minimum system exergy
destruction ratio (System EDR_Cascade),
power required to run whole system (all three compressors) in terms of exergy
of fluid (kW) and also minimum power required to run compressors , it is found
that system-2 of
three stage cascade vapour compression refrigeration system using
R1234ze(Z) in high temperature cycle between temperature range of (55oC
to 0oC) and R1233zd(E)in medium temperature cycle between
temperature range of (0oC to -70oC) and R1225ye(Z) in low
temperature cycle is best. However the above sixteen system can replace HFC
and HCFC refrigerants in near future .The best systems chosen, based on the
utility of HFO refrigerants in high temperature cycle Best systems are
system-2: R-1234ze(Z) in HTC, R1233zd(E)in MTC and R1225ye(Z) in LTC out of
four systems containing R1234ze(Z) in high temperature cycle while System-6:
R-1234ze(E) in HTC, R1233zd(E)in MTC and R1225ye(Z) in LTC out of four systems
containing R1234ze(E) in high temperature cycle while System-11: R1243zf in
HTC, R1233zd(E) in MTC and R1225ye(Z)in LTC out of four systems containing
R1243zf in high temperature cycle while System-15: R1233zd(E) in HTC,
HFO-1336mzz(Z) in MTC and R1225ye(Z)in LTC
out of two systems containing R1233zd(E)
in high temperature cycle in HTC and R-1224 yd(Z) in high temperature
cycle in remaining two systems
Table-1:
Three stage cascade vapour compression refrigeration system using ecofriendly
R1234ze(Z) refrigerant in high temperature cycle and other ecofriendly
refrigerants in medium and low temperature cycles (Q_Eva_LTC=35.167’kW’,
T_Cond_HTC=55oC, T_Eva_HTC=0oC,T_Eva_MTC=0oC,
T_aevs_LTC=-140oC,Temperature overlapping
between medium temperature condenser and high temperature evaporator=10, temperature
overlapping between low temperature condenser and medium temperature
evaporator=10.
Performance
Parameters
|
System-1
R-1234ze(Z)
|
System-2
R-1234ze(Z)
|
System-3
R-1234ze(Z)
|
System-4
R-1234ze(Z)
|
System
Cascaded COP_Cascade
|
0.3695
|
0.3815
|
0.3752
|
0.3646
|
System
Cascaded EDR_Cascade
|
4.763
|
4.635
|
4.730
|
4.84
|
System
Cascade Exergetic Efficiency_Cascade
|
0.1735
|
0.1775
|
0.1745
|
0.1712
|
System
Exergy of Fuel “kW”
|
95.18
|
92.18
|
93.73
|
96.44
|
System
Exergy of Product “kW”
|
16.51
|
16.31
|
16.36
|
16..51
|
High
Temperature Cycle Compressor Work_HTC“kW”
|
30.71
|
30.01
|
30.37
|
31.01
|
Medium Temperature Cycle Compressor Work_MTC“kW”
|
36.14
|
35.31
|
36.49
|
37.11
|
Low
Temperature Cycle Compressor Work_LTC“kW”
|
26.33
|
26.33
|
26.86
|
28.33
|
High
Temperature Cycle (Q_Cond_HTC ) “kW”
|
130.3
|
127.3
|
128.9
|
131.6
|
Medium
Temperature Cycle (Q_Cond_ITC) “kW”
|
99.63
|
97.37
|
98.52
|
100.6
|
Low
Temperature Cycle(Q_Cond_LTC) “kW”
|
63.49
|
62.03
|
62.03
|
63.49
|
Low
Temperature Cycle (Q_Eva_LTC) “kW”
|
35.167
|
35.167
|
35.167
|
35.167
|
High
Temperature Cycle COP_HTC
|
3.244
|
3.244
|
3.244
|
3.244
|
Medium
Temperature Cycle COP_MTC
|
1.757
|
1.757
|
1.70
|
1.711
|
LowTemperature
Cycle COP_LTC
|
1.242
|
1.309
|
1.309
|
1.242
|
High
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.6450
|
0.6301
|
0.6376
|
0.6512
|
Medium
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.4079
|
0.3985
|
0.4753
|
0.5432
|
Low
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.2024
|
0.2287
|
0.2287
|
0.2024
|
Cascade
COP_MTC
|
0.9498
|
0.9498
|
0.9277
|
0.9321
|
Cascade
EDR_MTC
|
1.002
|
1.002
|
1.128
|
1.168
|
Cascade
Exergetic Efficiency_MTC
|
0.4995
|
0.4995
|
0.4696
|
0.4612
|
Table-2:
Three stage cascade vapour compression refrigeration system using ecofriendly
R1234ze(E) refrigerant in high temperature cycle and other ecofriendly
refrigerants in medium and low temperature cycles (Q_Eva_LTC=35.167’kW’,
T_Cond_HTC=55oC, T_Eva_HTC=0oC,T_Eva_MTC=0oC,
T_aevs_LTC=-140oC,Temperature overlapping
between medium temperature condenser and high temperature evaporator=10,
Temperature overlapping between low temperature condenser and medium
temperature evaporator=10.
Performance
Parameters
|
System-5
|
System-6
|
System-7
|
System-8
|
System
Cascaded COP_Cascade
|
0.3506
|
0.3618
|
0.3559
|
0.3460
|
System
Cascaded EDR_Cascade
|
5.074
|
4.942
|
5.04
|
5.154
|
System
Cascade Exergetic Eff._Cascade
|
0.1646
|
0.1683
|
0.1656
|
0.1625
|
System
Exergy of Fuel “kW”
|
100.3
|
97.19
|
98.8
|
101.6
|
System
Exergy of Product “kW”
|
16.51
|
16.36
|
16.51
|
16.51
|
High
Temperature Cycle Compressor Work_HTC“kW”
|
35.86
|
35.02
|
35.45
|
36.2
|
Medium Temperature Cycle Compressor Work_MTC“kW”
|
36.14
|
35.31
|
36.49
|
37.11
|
Low
Temperature Cycle Compressor Work_LTC“kW”
|
28.33
|
26.86
|
26.86
|
28.31
|
High
Temperature Cycle (Q_Cond_HTC ) “kW”
|
135.5
|
132.4
|
134.0
|
136.8
|
Medium
Temperature Cycle (Q_Cond_ITC) “kW”
|
99.63
|
97.34
|
98.52
|
100.6
|
Low
Temperature Cycle(Q_Cond_LTC) “kW”
|
63.49
|
62.03
|
62.03
|
63.49
|
Low
Temperature Cycle (Q_Eva_LTC) “kW”
|
35.167
|
35.167
|
35.167
|
35.167
|
High
Temperature Cycle COP_HTC
|
2.779
|
2.779
|
2.779
|
2.779
|
Medium
Temperature Cycle COP_MTC
|
1.757
|
1.757
|
1.70
|
1.711
|
LowTemperature
Cycle COP_LTC
|
1.242
|
1.309
|
1.309
|
1.242
|
High
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.9387
|
0.9171
|
0.9282
|
0.9476
|
Medium
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.4079
|
0.3985
|
0.4753
|
0.5432
|
Low
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.2024
|
0.2287
|
0.2287
|
0.2024
|
Cascade
COP_MTC
|
0.8820
|
0.8820
|
0.8623
|
0.8662
|
Cascade
EDR_MTC
|
1.156
|
1.156
|
1.291
|
1.333
|
Cascade
Exergetic Efficiency_MTC
|
0.4639
|
0.4639
|
0.4365
|
0.4286
|
Table-3:
Three stage cascade vapour compression refrigeration system using ecofriendly
R1243zf refrigerant in high temperature cycle and other ecofriendly
refrigerants in medium and low temperature cycles (Q_Eva_LTC=35.167’kW’,
T_Cond_HTC=55oC, T_Eva_HTC=0oC,T_Eva_MTC=0oC,
T_aevs_LTC=-140oC,Temperature overlapping
between medium temperature condenser and high temperature evaporator=10,
Temperature overlapping between low temperature condenser and medium
temperature evaporator=10.
Performance
Parameters
|
System-9
|
System-10
|
System-11
|
System-12
|
System
Cascaded COP_Cascade
|
0.3544
|
0.3445
|
0.3602
|
0.3490
|
System
Cascaded EDR_Cascade
|
5.067
|
5.181
|
4.968
|
5.101
|
System
Cascade Exergetic Eff._Cascade
|
0.1648
|
0.1618
|
0.1676
|
0.1639
|
System
Exergy of Fuel “kW”
|
99.24
|
102.1
|
97.62
|
100.8
|
System
Exergy of Product “kW”
|
16.36
|
16.51
|
16.36
|
16.51
|
High
Temperature Cycle Compressor Work_HTC“kW”
|
35.88
|
36.64
|
35.45
|
36.29
|
Medium Temperature Cycle Compressor Work_MTC“kW”
|
36.49
|
37.11
|
35.31
|
36.14
|
Low
Temperature Cycle Compressor Work_LTC“kW”
|
26.86
|
28.33
|
26.86
|
28.33
|
High
Temperature Cycle (Q_Cond_HTC ) “kW”
|
134.4
|
137.2
|
132.8
|
135.9
|
Medium
Temperature Cycle (Q_Cond_ITC) “kW”
|
98.52
|
100.6
|
97.34
|
99.63
|
Low
Temperature Cycle(Q_Cond_LTC) “kW”
|
62.03
|
63.49
|
62.03
|
63.49
|
Low
Temperature Cycle (Q_Eva_LTC) “kW”
|
35.167
|
35.167
|
35.167
|
35.167
|
High
Temperature Cycle COP_HTC
|
2.746
|
2.746
|
2.746
|
2.746
|
Medium
Temperature Cycle COP_MTC
|
1.70
|
1.711
|
1.757
|
1.757
|
LowTemperature
Cycle COP_LTC
|
1.309
|
1.242
|
1.309
|
1.242
|
High
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.8301
|
0.8476
|
0.8203
|
0.8395
|
Medium
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.4753
|
0.5431
|
0.3985
|
0.4079
|
Low
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.2287
|
0.2024
|
0.2287
|
0.2024
|
Cascade
COP_MTC
|
0.8571
|
0.861
|
0.8767
|
0.8767
|
Cascade
EDR_MTC
|
1.305
|
1.347
|
1.169
|
1.169
|
Cascade
Exergetic Efficiency_MTC
|
0.4339
|
0.4260
|
0.4611
|
0.4611
|
Table-4:
Cascade vapour compression refrigeration system using ecofriendly (R-1224yd(Z)
and R1233zd(E) refrigerants in high temperature cycle (Q_EVA_LTC=35.167’kW’,
T_Cond_HTC=55oC, T_Eva_HTC=0oC,
T_Eva_MTC=0oC, T_aevs_LTC=-140oC,Temperature
overlapping between medium temperature condenser and high temperature
evaporator=10, Temperature overlapping between low temperature condenser and
medium temperature evaporator=10
Performance
Parameters
|
System-13
R-1224 yd(Z)
|
System-14
R-1224 yd(Z)
|
System-15
R1233zd(E)
|
System-16
R1233zd(E)
|
System
Cascaded COP_Cascade
|
0.3666
|
0.3563
|
0.3699
|
0.3596
|
System
Cascaded EDR_Cascade
|
4.864
|
4.976
|
4.813
|
4.924
|
System
Cascade Exergetic Efficiency_Cascade
|
0.1705
|
0.1673
|
0.1720
|
0.1688
|
System
Exergy of Fuel “kW”
|
95.93
|
98.69
|
95.08
|
97.82
|
System
Exergy of Product “kW”
|
16.36
|
16..51
|
16.36
|
16..51
|
High
Temperature Cycle Compressor Work_HTC“kW”
|
32.57
|
33.26
|
31.72
|
32.39
|
Medium Temperature Cycle Compressor Work_MTC“kW”
|
36.49
|
37.11
|
36.49
|
37.11
|
Low
Temperature Cycle Compressor Work_LTC“kW”
|
26.86
|
28.33
|
26.86
|
28.33
|
High
Temperature Cycle (Q_Cond_HTC ) “kW”
|
131.1
|
133.9
|
130.9
|
133.0
|
Medium
Temperature Cycle (Q_Cond_ITC) “kW”
|
98.52
|
100.6
|
98.52
|
100.6
|
Low
Temperature Cycle(Q_Cond_LTC) “kW”
|
62.03
|
63.49
|
62.03
|
63.49
|
Low
Temperature Cycle (Q_Eva_LTC) “kW”
|
35.167
|
35.167
|
35.167
|
35.167
|
High
Temperature Cycle COP_HTC
|
3.025
|
3.025
|
3.106
|
3.106
|
Medium
Temperature Cycle COP_MTC
|
1.70
|
1.711
|
1.70
|
1.711
|
LowTemperature
Cycle COP_LTC
|
1.309
|
1.242
|
1.309
|
1.242
|
High
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.8761
|
0.8945
|
0.7238
|
0.7391
|
Medium
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.4753
|
0.5432
|
0.4753
|
0.5432
|
Low
Temperature Cycle Mass flow Rate “Kg/sec”
|
0.2287
|
0.2024
|
0.2287
|
0.2024
|
Cascade
COP_MTC
|
0.8982
|
0.9024
|
0.9093
|
0.9136
|
Cascade
EDR_MTC
|
1.199
|
1.24
|
1.172
|
1.112
|
Cascade
Exergetic Efficiency_MTC
|
0.4547
|
0.4465
|
0.4603
|
0.4521
|
Table-5:
Optimum three stage cascade vapour compression system for low temperature
applications
First
and second law performance parameters of three stages vapour compression
cascaded refrigeration systems using HFO refrigerants for replacing HFC-134a
|
System-2
R1234ze(Z) in
HTC, R1233zd(E)in MTC and R1225ye(Z) in LTC
|
System-6
R1234ze(E)
in HTC, R1233zd(E)in
MTC and R1225ye(Z) in LTC
|
System-11
R1243zf in HTC, R1233zd(E) in MTC and R1225ye(Z)in LTC
|
System-15
R1233zd(E) in HTC,
HFO-1336mzz(Z)
in MTC & R1225ye(Z) in LTC
|
System
COP_Cascade
|
0.3815
|
0.3618
|
0.3602
|
0.3699
|
System EDR_Cascade
|
4.635
|
4.942
|
4.968
|
4.813
|
System
Exergetic Efficiency_Cascade
|
0.1775
|
0.1683
|
0.1676
|
0.1720
|
Exergy
of Fuel “kW”
|
92.18
|
97.19
|
97.62
|
95.08
|
Exergy
of Product “kW”
|
16.31
|
16.36
|
16.36
|
16.36
|
Compressor
Work_HTC“kW”
|
30.01
|
35.02
|
35.45
|
31.72
|
Compressor
Work_MTC“kW”
|
35.31
|
35.31
|
35.31
|
36.49
|
Compressor
Work_LTC“kW”
|
26.33
|
26.86
|
26.86
|
26.86
|
4.
Conclusions
Following conclusions were drawn from
present investigations.
The following conclusion were drawn:
·
Three
stage cascade vapour compression refrigeration system using R1234ze(Z) in high
temperature cycle between temperature range of (55oC to 0oC)
and R1233zd(E)in medium temperature cycle between temperature range of (0oC
to -70oC) and R1225ye(Z) in low temperature cycle at evaporator
temperature of -140oC is best
·
HFO
refrigerants have excellent potential for replacing R134a in near future. The
performance using R1234yf is slightly less than R134a . The other HFO
refrigerants gives better thermodynamic performances.
·
The
variation in the first law performance
between best four systems range is 5.91%
and 5.907% in terms of in second
law performance along with 6.62% of
exergy destruction range.
·
Therefore all sixteen
three stage cascade vapour compression refrigeration systems can replace highly GWP refrigerants (i.e.R134a, R410a, R404a, R407c,
R-236fa, R227ea) in near future
·
Although
R245fa and R32 and hydrocarbons can also be used but hydrocarbons have
flammable nature, therefore safety precautions to be taken before using.
References
[1]
Regulation
(EU) No 517/2014 of the European Parliament and of the Council of Fluorinated
Greenhouse Gases and Repealing Regulation (EC), No 842/2006 (2014)
[2]
Mishra
R.S.,(2020,):New & low GWP eco-friendly refrigerants used for predicting
thermodynamic (energy-exergy) performances of cascade vapour compression
refrigeration system using for replacing R134a, R245fa , and R32, International
Journal of Research in Engineering and Innovation Vol-4, Issue-3 , 124-130
[3]
Radhey
Shyam Mishra, Energy-exergy performance evaluation of new HFO refrigerants in
the modified vapour compression refrigeration systems using liquid vapour heat
exchanger , International Journal of Research in Engineering and Innovation
Vol-4, Issue-2 (2020), 77-85
[4]
Attila Gencer Devecioglu and Vedat
Oruc: A comparative energetic analysis
for some low-GWP refrigerants as R134a replacements in various vapor
compression refrigeration systems.Journal of thermal
science and engineering, 38(2):51-61 · October 2018
[5]
Sanchez,
D., Cabello, R., Llopis, R., Araguzo, I., Catalan-Gil, J., Torrella, E., Energy
performance evaluation of R1234yf, R1234ze(E), R600a, R290 and R152a as low-GWP
R134a alternatives, Int. J. Refrigeration, Vol-74, page-269-282 (2017).
[6]
Mota-Babiloni,
A., Navarro-Esbrí, J., Barragan, A., Moles, F., Peris, B.: Drop-in energy
performance evaluation of R1234yf and R1234ze(E) in a vapour compression system
as R134a replacements, Appl. Therm. Eng., 71, 259-265 (2014)
[7]
Mota-Babiloni,
A., Navarro-Esbrı, J., Barragan-Cervera, A., Moles, F., Peris, B.: Experimental
study of an R1234ze(E)/R134a mixture (R450A) as R134a replacement, Int. J. Refrigeration, 51, 52-58 (2015)
[8]
Mota-Babiloni,
A., Navarro-Esbrı, J., Barragan-Cervera, A., Moles, F., Peris, B.: Analysis
based on EU Regulation No 517/2014 of new HFC/HFO mixtures as alternatives of
high GWP refrigerants in refrigeration and HVAC systems, Int. J. Refrigeration, 52, 21-31(2015)
[9]
Yang,
W.-W.; Cao, X.-Q.; He, Y.-l.; Yan, F.-Y. Theoretical study of a
high-temperature heat pump system composed of a CO2 transcritical
heat pump cycle and a R152a subcritical heat pump cycle. Appl. Therm. Eng. 2017, 120, 228–238
[10] Bolaji, B.O. Experimental
study of R152a and R32 to replace R134a in a domestic refrigerator. Energy 2010, 35, 3793–3798.
[11] R. Cabello, D. Sánchez, R. Llopis, J. Catalán, L. Nebot-Andrés, E. Torrella [2017], Energy evaluation of R152a as
drop in replacement for R134a in cascade refrigeration plants, Applied thermal
Engineering,. Vol- 110 ,page- 972-984
This article is published in peer review journal and open access journal, International journal of research in engineering and innovation (IJREI) which have a high impact factor journal for more details regarding this article, please go through our journal website.
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