Page 90 - Low Temperature Energy Systems with Applications of Renewable Energy

Characteristics of low-temperature energy sources for heat pumps 79

Fig. 2.24 Specific external energy losses for heating as a function of the temperature of the
working fluid (brine solution) t input at the evaporator inlet (temperature of the working fluid
ev:

t w.f. ¼ 40 C): curves 1, 2, 3 correspond to A ¼ 0.005, 0.015, 0.027 C.

Fig. 2.25 Optimal working fluid temperature difference in the evaporator as a function of the

factor A: 1, 2, temperature of working fluid (brine solution) at evaporator input t in ¼ 2, 5 C.
w:f :
arenas, concert halls, and medical complexes. The sources of heat can be the
following: ambient air (with temperatures as low as 25 C); air of ventilation systems

(þ15 to 25 S); well water and urban water effluents and ones from industrial enter-

prises (from 5 to 20 C); water of open reservoirs and upper layers of oceans (up to
20 C); return water of thermal power plants and boiler heating plants (from 30 to

50 C); and soil heat at a depth of 100 m (from 4 to 10 C). Each of these sources