A car air conditioning system operates with R-134a in the peak summer (Outside at 100°F and inside desired at 77°F). The low pressure side of the system operates at 90 psia and the high pressure side is at 300 psia. The cooling load (required QL) is 200 Btu/min.
a. Show the cycle on a T-s diagram with respect to saturation lines and including both isobars.
b. Determine the amount of work required to operate the A/C if all processes are ideal. [Btu/min].
c. Convert this required to kW. Compare this value to the project system. Is the A/C a significant portion of the engine work?
d. Is there any potential problem with the specified operating pressures? (HINT: What do you need for heat transfer to occur?).
e. What is a simple way to increase the performance and eliminate the problem from part d? Are there any side effects of this change?