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340 Defrosting for Air Source Heat Pump

improved. The total running cost decreased by as much as 3681.75 CNY, or 10.33%,
and the total cost 3516.75 CNY, or 4.67%, over 15 years’ service life. After installing
both the water-collecting trays and valves, the running cost of the new ASHP unit in
the heating season with frost formation decreased by 2540.36 CNY, or 11.95%, and
in the heating season without frost formation the decrease was 1141.37 CNY, or
7.64%. The effect of valves on the economic performance of the ASHP unit is obvi-
ously better than that of trays. After water-collecting trays were installed, the total cost
decreased by 283.98 CNY. But the saved cost after the valves were installed enlarged
12.27 times, at 3484.34 CNY.

10.4 Concluding remarks

Two technoeconomic analyses on frosting/defrosting operations for an optimized
ASHP unit are presented in this chapter. The first one considered two conditions, with
trays installed in the multicircuit outdoor coil. For the second one, four conditions,
with trays and/or valves installed in the outdoor coil, were considered. As analyzed,
after the water-collecting trays and/or valves were installed, the economic perfor-
mances of an ASHP unit were effectively improved. Over 15 years’ service life,
the total running cost was decreased by as much as 10.33%, and 4.67%. After
installing both the water-collecting trays and valves, the running cost of the new
ASHP unit in the heating season with frost formation was decreased by 11.95%,
and in the heating season without frost formation by 7.64%. The effect of installing
valves on the economic performance of the ASHP unit is obviously better than that of
installing trays. After water-collecting trays were installed, the total cost was
decreased while the saved cost after the valves were installed was enlarged. The pay-
back period for the additional initial cost was calculated at only 0.65 year. Electricity
unit price variations were further discussed.

References

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