PROBLEM 1.1 STATEMENT: Refrigerant enters the compressor of a refrigerator at (P1=100,110,120,130,140,150,160,170,180,1

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PROBLEM 1.1 STATEMENT:

Refrigerant enters the compressor of a refrigerator at (P1=100,110,120,130,140,150,160,170,180,190,200) kPa and -10C at a rate of

0.3 m3

/min and leaves at 1 MPa. The isentropic efficiency of the compressor is 78%. The refrigerant enters the throttling valve at 0.95

MPa and 30C and leaves the evaporator as saturated vapor at 18.5C. Show the cycles on P-h diagram with respect saturation lines, for

R134a, R22, and R12, determine:

a. The power input to the compressor,

b. The rate of heat removal from the refrigerated space,

c. The pressure drops and rate of heat gain in the line between the evaporator and compressor, and

d. Plot the COP for various refrigerant and discuss your results.

PROBLEM 1.2 STATEMENT:

The conditions at the beginning of compression in an air-standard Diesel cycle are fixed by P1=

100,110,120,130,140,150,160,170,180,190, and 200 kPa, T1 = 380 K. The compression ratio is 20 and the heat addition per unit mass

is 900 kJ/kg. Use k = 1.4 for air/fuel mixture (compression) and k = 1.34 for combustion products (expansion). Determine

a. The thermal efficiency of Diesel cycle for various P1,

b. Plot the thermal efficiency vs P1, and

c. In one plotting window, plot the cycles on a T-s diagram for various P1.

Use EES program for both problems.