Question

In your refrigerator the working substance evaporates from liquid to vapor at -20 °C inside a pipe around the cold section. Outside (on the back or below) is a black grille inside which the working substance condenses from vapor to liquid at +40 °C. For each location find the pressure and the change in specific volume (v) if: 

(a) the substance is R-134a 

(b) the substance is R-22 

Answer 1

The properties come from the saturated tables where each phase change takes place at constant pressure and constant temperature.

Substance	T	Psat , kPa	∆v = vfg
R-134a	40 °C	1017	0.019
R-134a	40 °C	134	0.146
R-22	40 °C	1534	0.0143
R-22	40 °C	245	0.092