and an inverter-type air conditioner (IAC). The schematic
diagram is shown in Fig. 4. ECS is coupled with IAC at the
intercooler, which is the evaporator of ECS or the sub-cooler of
IAC. The cooling load of the cooling room is designed at 3.5 kW
(1RT) which matches the rated cooling capacity of the IAC
used. The cooling capacity of the ECS is 5.6 kW which is able to
cool the condenser of the IAC at a lower temperature to
increase the COP of IAC. The system specification is shown in
Table 1. R245fa is used as the working fluid of ECS.
2.2. Solar heating system
The solar heating system used in SACH-k2 is the same as that
used in the study of MPPT (maximum-power-point tracking)
control of pump (Huang et al., 2012). The solar heating system
consists of 24 flow-through vacuum-tube collectors (Model
EZL100-6) with 26 m2 total absorber area. Eight collectors are
connected in series and three in parallel. Glycol solution is
pumped from the buffer tank through the solar collector and
absorbs solar energy to heat the generator of ECS. The flow
then returns to the buffer tank as shown in Fig. 4. An inverter
for rotational speed control of the circulation pump was
installed and a PC-based control system was developed for the
MPPT control of the circulation pump.
This solar heating system can supply hot water at temperature
in the range 70e130 C to drive the ejector cooling
system. A buffer tank (200 L) is used as a storage for stable
pumping. The test of solar collector shows that the thermal
efficiency of the solar heating system is 0.6 at water inlet
temperature 100 C (Huang et al., 2010a,b).
2.3. Ejector cooling system (ECS)
The flow diagram of ECS is as shown in Fig. 4. ECS and IAC
are linked at the intercooler which is the evaporator of ECS
and the condenser of IAC. The cooling capacity of ECS is
5.6 kW rated at condenser temperature 40 C, generator