CHAPTER 3.THE VAPOR COMPRESSION CYCLE ratio of the mass of saturated vapor to the total mass,and designated by the symbolx. On average the liquid-vapor mixture has v=(1-x)v'+xv" 3.11a h=(1-x)h'+xh" 3.11b 5=(1-x)S+xS" 3.11c where the suffices'and"refer to saturated liquid and saturated vapor,respectively,and v=specific volume h=specific enthalpy s=specific entropy x=quality of the mixture. With a known value of the enthalpy hd =ha=hs we get for point a hs=(1-x).h +x.h2" and rearrangement gives the quality of the mixture as x=(h-h3)/(h3-h3)=(h-h3)r 3.11d where r is the latent heat of vaporization at the temperature T2. 3.12 The quantities of most interest,i.e.the refrigerating effect,the work of compression,and the heat rejected at the condenser,all can be read on the enthalpy scale in the p-h diagram.They are represented by the distances marked at the bottom of the p-h diagram in Figure 3.06.The Equation 3.01 is clearly illustrated in this diagram;on a per unit mass basis.In a T-s diagram the quantities are represented by areas,which will be discussed in section 3.22. 3.13 Example:A vapor compression system operating with ammonia,NH3,in a cycle according to Figures 3.04 and 3.06 is going to be designed for a refrigerating capacity of =11,6 kW when the evaporating temperature is t2=-15C and the condensing temperature is t=+30C.The inlet temperature to the expansion device is fs=+25C,the outlet temperature from the evaporator is tak=t2=-15C, and the compressor operates adiabatically with the total isentropic efficiency T= 0,75. Calculate a)the mass flow rate of the circulating refrigerant,m b)the power input to the compressor,E c)the condenser load,O d)the quality of the mixture at the outlet of the expansion valve,x e)the ratio of the refrigerating capacity to the power input to the compressor,/E. 3:11