means 80% energy reduction. But ESC can still operate under
critical mode.
3.3. Evaporator temperature control of ECS
In order to make ejector operate under critical or non-critical
double-choking condition, an electronic expansion valve
was installed at the evaporator inlet to regulate the opening of
the expansion valve to control the evaporator temperature
according to the variation of solar radiation. The feedback
tracking control system is as shown in Fig. 9.
The test result shown in Fig. 19 was performed at average
ambient temperature 34 C and cooling room temperature
26.9 C with additional electric heating load 2.6 kW. It is seen
that the tracking of Tg and Te was satisfactory. A larger control
error on Tg was observed as solar radiation drops and varies.
The control error of Te is less than 1.5 C at stable solar radiation
and about 3 C at abrupt solar radiation change.
Fig. 20 shows that at solar irradiation about 790W m2, the
power consumption of IAC decreases from 992 W to 512 W, a
reduction of 48%, when the solar-driven ECS is activated and
operating at Tg ¼ 96 C and Te ¼ 20 C, and IAC condenser