Consider a reversed Stirling cycle applied as a refrigerator. Assume each proces
ID: 1819427 • Letter: C
Question
Consider a reversed Stirling cycle applied as a refrigerator. Assume each process is frictionless and internally reversible with Helium Gas as the working fluid. The refrigeration cycle has a cooling capacity of 30 J/s from a chilled region at 70 K. The outdoor environmental temperature is 290 K. The external heat exchangers are sized to reach a 10 K difference from limiting temperatures (cycle T_min< T_c-10K, cycle T_max>T_H+10K). Assume that internal heat transfer in the cycle is perfectly reversible. The minimum pressure in the cycle is 50 kPa and the compression ration V_max/V_min=4. The cycle executes in a piston-cylinder device operating at 60 cycles/s. There are no significant changes in potential and kinetic energy. This is a small device (J/s not kJ/s). Carefully sketch p-v and T-s cycle diagrams and organize a state table showing (p,v,T) for each state.a) Find the reversed Stirling cycle COP
b) Find the specific heat transfer for each process.
c) Find the mass Helium in the cylinder and the max cylinder volume.
d) Find the entropy production for each process.
Explanation / Answer
1+1=2