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A heat pump with refrigerant R22 is used for space heating between temperature limits of – 20°C and 25°C. The heat required is 200 MJ/ h. Assume specific heat of vapour at the time of discharge as 0.98 kJ/kgK. Other relevant properties are given below. The enthalpy (in kJ/ kg) of the refrigerant at isentropic compressor discharge is_________.
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- 433.3
- 433.9
- 433.8
- 433
Correct Option: A
Given :T1' = 253 K
T2' = 298 K
S1 = S2 = S2'
| ∴ S1 = S2 = S2' + CP ln | T2' |
| 1.7841= 1.7183 + 0.98 ln | 298 |
∴ T2 = 318.69 K
∴ Enthalpy of discharge of compressor
⇒ h2 = h2' + Cp (T2' – T1')
∴ h2 = 413.02 + 0.98 (318.69 – 298)
∴ h2 = 433.3 kJ/kg .
