A10 kw cooling load is to be served by operating an ideal vapor-compression refrigeration cycle with its evaporator at 400 kpa and its condenser at 800 kpa. calculate the refrigerant mass flow rate and the compressor power requirement when refrigerant-134a is used. (take the required values from the saturated refrigerant-134a tables.)

b) w = 0.927211 kW

Explanation:

from table R-134 a

state 1  

P-1 = 400 kPa

h_1 = [email protected] kpa = 255.55 kJ?kg

s1 = s2 = 0.92961 kJ/kg K

state 2

P-2 = 800 kPa

s2 =s1 = 0.92691

s2> [email protected] 800 kPa = 0.92691 kJ/ kg K

from superheated table for R-134 a at pressure of 800 kPa

using interpolation for obtaining desire value of temperature and enthalapy

T_2 = 34.75 degree C

FOR  ENTHALAPY

h_2 = 270.3928 kJ/kg

state 3

state 4  ( h remain constant)

a) mass flow rate

b) compressor power

w = 0.062456(270.3928 - 255.55)

w = 0.927211 kW