13468-11-77P AID: 1825 | 05/12/2014

Show the layout of the ideal gas refrigeration cycle with two stages of compression with intercooling using air as the working fluid as in Figure (1).

Show the ideal-gas refrigeration cycle, with two stages of compression and intercooling and with air as the working fluid, on diagram as in Figure (2).

For the given ideal-gas refrigeration cycle, with two stages of compression and intercooling and with air as the working fluid, the temperature, specific enthalpy, and pressure at state are , , and respectively.

Use ideal-gas specific heats of various common gases table, to find and the properties of air at room temperature.

(a)

Express the temperature and pressure relation for the isentropic process 1-2.

Here, the specific heat ratio of air is k.

Substitute 249 K for , 3 for , and 1.4 for k to find .

Express the temperature and pressure relation for the isentropic process 3-4.

Substitute 278 K for , for , and 1.4 for k to find .

Express the temperature and pressure relation for the isentropic process 5-6.

Substitute 278 K for , for , and 1.4 for k to find .

Find the COP for the given ideal-gas refrigeration cycle .

Here, the amount of heat per unit mass, removed from the refrigerated space is , the specific work input to the compressor is , and the specific work output from the turbine is .

Substitute 249 K for , 380.5 K for , 278 K for , 340.8 K for , 278 K for , and 148.4 K for .

Hence, the COP for the given ideal-gas refrigeration cycle with two stages of compression and inter cooling is .

Find the mass flow rate of air for the given ideal-gas refrigeration cycle .

Here, the total amount of heat removed from the refrigerated space is .

Substitute for , for , 148.4 K for , and 249 K for .

Hence, the mass flow rate of air for the given ideal-gas refrigeration cycle with two stages of compression and inter cooling is .