Page 87 - Low Temperature Energy Systems with Applications of Renewable Energy

76 Low-Temperature Energy Systems with Applications of Renewable Energy

Fig. 2.20 Optimal degree of air cooling in the evaporator as a function of the factor A: 1, 2:

Ambient temperature, t 0 ¼ 20 to þ15 C.
It is clear from the curves 1e5 that for each value of inlet water temperature there
are optimal water temperature values at the evaporator outlet that yield minimum spe-
cific losses of external energy.
To determine the optimal water temperature difference between the evaporator inlet
and outlet, Eq. (2.19) can be used by replacing the ambient air temperature t o with the
in
water temperature at the evaporator inlet t ev .

Fig. 2.21 Specific external energy losses for heating as a function of water temperature at the

evaporator outlet at t w.f. ¼ 30 C (at A ¼ 0.01 C): 1e5 are water temperature at the evaporator
inlet, t in ¼ 4, 8, 12, 16, 20 C, respectively.

ev