Question

1. Mark the following data on PH chart and calculate Coefficient of performance and heat rejected in condenser. The mass flow rate of refrigerant is 0.25 kg/s. The refrigerant used is 134a.          

                              Condenser pressure = 10 bar

                               Evaporator pressure = 0.4 bar.

                              Compressor inlet temperature = -20 ℃

                              Expansion device inlet temperature = 30 ℃                                         

                                                                                                          

Answer 1

In this problem, first find the specific enthalpy of Refrigerant at each state of the cycle from p-h chart of the refrigerant R-134a and then Calculate the coefficient of performance of cycle and heat rejected in condenser as below:-

Ciren data :-( Refrigerant R-1340) (bar) to- 18= constant (+83k/sk) 0.4 Ft- m P, - PA = 0.4 bar P2 = P3= 10 bar T= -20°C Tz = 30°C mp= 0.25 kg ls Selution : - CAM data taken from P-h diogram of R-134 a)' (i) At state 1 (od bar & -20°c): 1 h = 338 koleg & S, = 1.83 koleg-k ü At state 2 ( 10 bar & S2 = 8,): - ha = 456 Koling ("? At state 3 ( 10 bar f 30°c): 1. hs = 240 kilng (iv) At state 4 (O.A bor & ha= hs): h = 240 kolag. Coefficient of performance (COP):- COP = Refrigeration that - Work input - malh-ha) (388-240) Cop- e melha-hy] (456-388) cope

Copa del Rei CoP = 2:176 Heat rejected in condenser (Qc):- de = mp (he-hs) = 8:25 (456 - 240) kW Te = 54 KW