Question

5. The refrigeration system shown below is another variation of the basic vapor compression refrigeration system which attempts to reduce the compression work. In this system, a heat exchanger is used to superheat the vapor entering the compressor while sub-cooling the liquid exiting from the condenser Consider a system of this type that uses refrigerant-134a as its refrigerant and operates the evaporator at -10°C, and the condenser at 900 kPa. Detemine the system COP when the heat exchanger provides 5.5°C of sub-cooling at the throttle valve entrance. Assume the refrigerant leaves the evaporator as a saturated vapor and the compressor is isentropic Condenscr Compressor Evaporator

Please also draw the T-S diagrams and PH diagrams to facilitate understanding. Thank you.

Answer 1

(R-13Ha) diagsam Soluton T-S & Cond Comp exe evap ptoperties f State-3 states at R-134a various 12.3 |14g Jol. 62 900 КРа 35. S KIg Tsat , Stale-u Tempezatune at stale-4 Ty= Ta - 5.5 = 30.01 is given 30°c = 93.58- thnatling psocess 93.5 K24 State- 5 State 6 TE = -10°C I (sat. Vapo) Кра. 200. 74 ОС6 — Reat exchanger halance using mha-mu h1R3-yth6

93.58 244, 5S =1ol. 6 2- 252.59 1/SH At, State-i 200.74 KРА 252.59 K3 T-HOfS P,- 900 Kpa h2= 285.4Kg The Cop of Refeigenation -> given he-Rs 244.55-93.58 252.59 285.4 op Ч.6 0134