A refrigeration process with interstage cooling uses refrigerant R134a, and the outlet of the condenser is to be saturated liquid at 40°C. Refer to Fig. 5.10 for stream numbers in your solution. The pressure of the flash chamber and the intermediate pressure between compressors is to be 290 kPa. The evaporator is to operate at -20°C and the outlet is to be saturated vapor. The flow rate of stream 1 is 23 kg/h. The flash chamber may be considered adiabatic. The compressors may be considered to be 80% efficient. Attach the P-H chart with your solution.
(a) What is the work input required to the first compressor in kJ/h?
(b) What are the flow rates of streams 7 and 6?
(c) What is the enthalpy of stream 4?

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Flash Chamber 8 6 Hot Side Condenser Throttle Valve 7 1 Throttle Valve Vapor Phase Only Evaporator Cold Side 2nd Stage Compressor 5 1st Stage Compressor Figure 5.10 Flash chamber intercooling. 2 T P Liquid 8, 6 /4 const. P H 4 7 Two-Phase Region S 3 5