Effect of Short Cycling and Fan Delay on the Efficiency of a Modified Residential Heat Pump.
Effect of Short Cycling and Fan Delay on the Efficiency
of a Modified Residential Heat Pump.
Mulroy, W. J.
ASHRAE (American Society of Heating, Refrigeration and
Air-Conditioning Engineers) Transactions, Vol. 92, No.
Part 1, January 1986.
heat pumps; air conditioning; fans; valvs; test
facilities; data analysis
The object of this study was to detennine if the use of
a cycling controller would improve the efficiency of a
residential air conditioner or heat pump. Cyclic tests
were perfonned on a capillary tube heat pump in three
configurations: as manufactured, as modified to simulate
a non-bleed expansion valve unit by operation of a valve
in the liquid line, and as modified to simulate an air
conditioner by elimination of the accumulator. The two
modifications, the liquid line valve installation and
accumulator removal, were found to greatly improve the
cyclic perfonnance to about equal levels; however, some
cyclic losses remained. It was concluded that any
control strategy that resulted in shortened on-cycle run
times would reduce cyclic efficiency for all designs
tested. It was further concluded, based in part on the
work of others, that fan delay is an undesirable control
strategy for units that have the indoor air handler and
coil installed within the conditioned space.