Work assignment

A refrigeration cycle using R$134$a is shown in the log pressure versus enthalpy plot. This cycle uses a throttle valve. The enthalpy and entropy values in the plot are from tables for R$134$a$.$ Calculate:

Heat transferred at low temperature $(-20$ F $)$ and at high temperature$(80$ F $).$

Work input to refrigerator.

The coefficient of performance for the refrigerator $(CO{P}_{\text{r}\text{e}\text{f}})$ for the cycle.

The COP if the compressor is only $70\%$ efficient.

Draw the process in the $p-h$ diagram