PERFORMANCE OF REFRIGERATION SYSTEM USING ENVIRONMENTALLY FRIENDLY REFRIGERANT

Abstract

The aim of this study is to experimentally investigate the usage of liquefied petroleum gas (LPG) as a substitute refrigerant for R134a in a household refrigerator and identify the most suitable charge and capillary tube length. The gravimetric composition of the locally available LPG by weight is (R290- 25.98%, R600-41.17%, R00a-9.99%, R601a-0.64%, R170-0.11%, R744-0.01%, butene-22.10%), Appendix D.

Five different charges at which LPG and R134a are charged and tested. The charges are 40 g and 50 g for LPG and 130 g, 150 g and 170 g for R134a. Four capillary tubes of 0.7 mm inner diameter, 1.9 mm outer diameter and 1.5 m, 2 m, 2.5 m and 3 m length each are used during experimentation at different thermostat positions (1, 2, and 3). REFPROP-6.0 software is used to determine the thermodynamic properties of LPG and R134a.

The results indicate that maximum COP and minimum irreversibility for R134a is attained at a charge of 130g, capillary tube length 1.5m and consequently the maximum exergy efficiency. On the other hand, the best performance for LPG is attained at a charge of 50 g and capillary tube length 1.5m. Relative to R134a, LPG has a COP and exergy efficiency that are lower by an average of 24% and 49%, respectively, within the range studied. However, LPG consumes less power and has more on time ratio compared to R134a. Also, LPG is cheap, available in great amounts and has a very low GWP and zero ODP.