Performance Analysis And Comparison Of Vapour Compression Refrigeration System Using R-134a And...

ISSN: 2395-0560 International Research Journal of Innovative Engineering

www.irjie.com Volume1, Issue 3 of March 2015

__________________________________________________________________________________ 2015 ,IRJIE-All Rights Reserved Page -89

Performance Analysis And Comparison Of Vapour Compression Refrigeration System Using R-134a And

R-600a Refrigerants Shubham R. Yennawar1, Prajyot P. Borkar2, Akshay S. Harkare3,Vishnu L. kale4,Abhilash K.

Kamble5,Vineet A. Bhandari6

1J.D.I.E.T.,Yavatmal, 445001, India ,2J.D.I.E.T., Yavatmal, 445001, India 3J.D.I.E.T.,Yavatmal, 445001, India 4J.D.I.E.T., Yavatmal, 445001, India 5J.D.I.E.T.,Yavatmal, 445001, India 6J.D.I.E.T., Yavatmal, 445001, India

Abstract - The performance of heat transfer is one of the most important research areas in the field of thermal engineering. There are a large number of refrigerants, which are used to transfer heat from low temperature reservoir to high temperature reservoir by using vapour compression refrigeration system. This paper presents a performance analysis of vapour compression refrigeration system with using refrigerants like R-134a & R-600a (Isobutane). Various performance measures like compressor discharge temperature, pressure ratio, volumetric cooling capacity (VCC), volumetric efficiency and mass flow rate are analyzed. The performance in term of coefficient of performance (COP), refrigerating capacity (RC), and compressor work (We) were evaluated for the investigated refrigerants at various evaporating and condensing temperatures. The system performance increases as the evaporating temperature increases, but reduces as the condensing temperature increases. The COP of R134a obtained was lower than R-600a (isobutane). Keywords: Refrigerant, Isobutane, Vapour Compression Refrigeration System, R-134a, R-600a(Isobutane) 1. Introduction

The ozone depleting potential (ODP) and global warming potential (GWP) have become the most important criteria in the development of new refrigerants apart from the refrigerants CFCs due to their contribution to ozone layer depletion and global warming. In spite of their high GWP, alternatives to refrigerants CFCs and HCFCs such as hydro fluoro carbon (HFC) refrigerants with the zero ODP and hydro carbon refrigerants (HC) have been preferred for use in many industrial and domestic applications. The presence of fluorine atoms in HFC134a is responsible for the major environmental impact (GWP) with serious implications for the future development of the refrigeration based industries.

For this reason, a more efficient and environment being alternative refrigerant is needed in the refrigeration system. The

natural refrigerants are naturally occurring substances such as ammonia, hydrocarbons, carbon dioxide, water and air. In this group, the hydrocarbons are most closely related to the HFCs. Their thermodynamic and transport properties are very similar to most HFCs currently used in refrigeration and air-condition systems, which make them suitable as substitute refrigerants in the existing HCFC and HFC systems without any major changes in the design.

The present study mostly concentrates on the performance of the vapour compression refrigeration cycle. The refrigerant

HC R600a is used as the working fluid for the comparison with the conventional refrigerant R134a. The effects of the main parameters like compressor discharge temperature, pressure ratio, volumetric cooling capacity (VCC), volumetric efficiency and mass flow rate are analyzed.

The performance in term of coefficient of performance (COP), refrigerating capacity (RC), and compressor work (We) were evaluated for the investigated refrigerants at various evaporating and condensing temperatures.




The system performance increases as the evaporating temperature increases, but reduces as the condensing temperature increases. The COP of R134a obtained was lower than R-600a (isobutane)

Table1. Refrigerant data comparison

2.Compatibility R600a as refrigerant In order to use R600a as suitable refrigerants, a comparative study of its individual thermo-physical

properties has been carried out. Thus, based on the data presented, one can notice that fluids molar mass, triple point temperature (t triple ), critical point pressure (p ) and also for temperature (t min , t max ), pressure (p max) and density ( max) in regard with their range of application. Both fluids present several desired refrigerant properties such as: critical pressure over 35 bar, critical temperature (t K ) over 95C, evaporating temperature (t0 ) below zero and increased latent heat of vaporization (q v0 ), both at atmospheric pressure, and also a small adiabatic exponent (k). Regarding the evaporating temperature at the atmospheric pressure one can notice that R600a presents a lower value making it suitable for refrigeration applications. At the same time R600a have an almost double latent heat of vaporization compared to CFCs, HCFCs and HFCs refrigerants.

This is a very important advantage concerning R600a in order to use it as refrigerants. Besides their thermodynamic properties which make R600a suitable as refrigerants, various papers on its use in domestic, commercial and industrial applications prove as well that R600a compatible with the commonly used materials

Refrigerant R 600a R 134a

Name Isobutane 1,1,1,2-Tetra- flouro-ethane

Formula (CH3) 3CH CF3-CH2F

Critical temperature 135 101 in C

Molecular weight 58.1 102 in kg/kmol

Normal boiling point -11.6 -26.5 in C

Pressure 0.58 1.07 at -25 C in bar (absolute)

Liquid density 0.60 1.37 at -25 C in kg/l

Vapour density 1.3 4.4 at to-25/+32 C in kg/m

Volumetric capacity 373 658 at -25/55/32 C in kJ/m

Enthalpy of vaporization 376 216 at -25 C in kJ/kg

Pressure 3.0 5.7 at +20 C in bar (absolute)




in VCRS. The suitability as refrigerants, from a thermodynamic and functional points of view suggest that R600a, as natural substances having ODP=0 and GWP




4. Comparison of Refrigerants

Parameter R-134a R-600a

T1(0C) -1.0 18.8

T2(0C) 67 44.1

T3(0C) 52.3 37.02

T4(0C) -10.1 -5.3

H1(KJ/Kg) 397.51 647.3

H2(KJ/Kg) 428.25 548

Hf3(KJ/Kg) 274.71 275.5

H4(KJ/Kg) 274.71 275.5

V(volt) 230 230

I(ampere) 0.9 0.7

Pd(bar) 11.2 6.8

Ps(bar) 0.35 1.67

Table 2.Observation from test rig of refrigerator using R-134a and R600a as refrigerant

4.1. For R134a Power, P = VICOS

P = 2300.900.85 P = 171.81 J/sec

But P = mr (h2-h1) 171.81 = mr (428.25-397.51) `mr = 5.589 gm/sec

Refrigerating Effect, R.E = mr (h1-hf3) R.E = 5.589 (397.51- 274.71) R.E = 686.32 J/sec

Work done, W.D = mr (h2-h1) W.D =5.589(428.25-397.51) W.D = 171.80 J/sec

Coefficient of Performance, COP = RE/ WD COP = 686.32/171.80 COP = 3.99

4.2.For R600a Power, P = VICOS

P = 2300.900.85 P = 136.85 J/sec

But P = mr (h2-h1)




136.85 = mr (645.3-578) mr = 2.033 gm/sec

Refrigerating Effect, R.E= mr (h1-hf3) R.E = 2.033(578-275.5) R.E = 614.98 J/sec

Work done, W.D = mr (h2-h1) W.D =2.033(645.3-578) W.D = 136.82 J/sec

Coefficient Of Performance, COP = RE/ WD COP = 614.98/136.82 COP = 4.53

5. CONCLUSION

In this study, an ideal vapour compression refrigeration system is used for the performance analysis of alternative refrigerant as substitute for R-134a which is R-600a. Considering comparison of coefficient of performance(COP) and load ratios of the tested refrigerants and also the main environmental impact of ozone layer depletion and global warming, refrigerant R-600a is found to be the most suitable alternative. For reducing the harmful effects on environment, it is necessary to use the refrigerant R-600a with low GWP and ODP. R-600a is refrigerant having high COP with less environmental impact.

REFERENCES [1] Y.S.LEE & C.C.SU, Experimental studies of isobutene (R600a) as the refrigerant in domastic refrigeration system

Applied Thermal Engineering 22, pp. 507-519,2002. [2] B.O.BOLAJI, M.A. Akintunde, T.O. Falade, comparative analysis of performance of three ozone friends HFC

refrigerants in a vapour compression refrigerator, journal of sustainable energy and environment 2(2011) 61-64. [3] B.O.BOLAJI, selection of environment-friendly refrigerants and the current alternative in vapour compression

refrigeration system, journal of science and management, vol 1. No. 1 (2011) 22-26 [4] James M. Calm, emission and environmental impact from air-conditioning and refrigeration system, International

Journal of Refrigeration 25, pp. 293-305,2002. [5] Samira Benhadid-Dib, and Ahmed Benzaoui, refrigerants and their impact in the environment. Use of the solar

energy as the sourcr of energy, Energy Procedia 6, pp. 347-352, 2002.Ji J Chow T [6] Eric Granryd, hydrocarbons as refrigerants an overview International journal of refrigeration 24, pp. 807-816,

2012 [7] Sandip P. chavhan& S.D. Mahajan, A review of an alternative to R-134a refrigerant in domastic refrigerator,

International Journal of Emerging Technology and Advanced Engineering volume 3, issue 9, pp.550-556 (2013)

ACKNOWLEDGEMENT It gives me immense pleasure to submit the paper topic entitledPerformance Analysis And

Comparison Of Vapour Compression Refrigeration System Using R-134a And R-600a Refrigerants. It is believed that our heartiest gratitude with pleasure is towards my guide Dr. R. U. Sambhe (Associate Prof. & Workshop Superintendant) , Prof. S. J. Kadam,J.D.I.E.T, Yavatmal, which gave us an opportunity in fulfilling our desire of reaching our goal. The satisfaction that accompanies the successful completion of any task would be incomplete without the mention of all people who deserve it. Last but not least, we would like to thanks our entire friend for their timely suggestion during the project.

Performance Analysis And Comparison Of Vapour Compression Refrigeration System Using R-134a And...

Documents

Transcript of Performance Analysis And Comparison Of Vapour Compression Refrigeration System Using R-134a And...