3. Results and analysis
3.1. The influence of the water pre-heated loops on the system
performance
The operating duration of the compressor was measured in
these two different experiment schemes, and the corresponding
results were 32.3 min and 29.4 min, respectively.
Fig. 3 depicts the temperature rise of tap water passing through
the water pre-heated loops. The temperature of the incoming tap
water was 15.0 C. The temperature rise increased rapidly in the
very initial stage, and then it maintained stable (approximately
5.5 C). This was because immediately after start-up of the experiment,
the SDW only flowed on the pre-heated water tubes surface.
From 4.0 min forward, the figure jumped to a high level, reaching
its peak at 10.8 C at 8.0 min. After that, it experienced a downward
trend for about 2.0 min before keeping almost stable at
9.6 C for the final stage of the shower. The significant jump of
the temperature rise was mainly due to the process in which the
pre-heated water tubes was immerged gradually by the SDW,
and thus more waste heat of SDW was absorbed by the tap water,
leading to a high temperature rise. With respect to the drop of the
figure from 8.0 min to 10.0 min, this phenomena was the result of
heat transfer from the SDW to the tap water and the refrigerant
thus making the reduction in the temperature of the SDW.
Besides, the mean temperature rise in Exp. 2 was 8.3 C. The experimental
results showed that part of the waste heat in the SDW
could be recovered with the water pre-heat loops. Therefore, the
water pre-heated loops had a better effect on the system
performance.
The