Performance of residential air-to-air heat exchangers during operation with freezing and periodic defrosts
Year: 1984
Type: article
Abstract: In a laboratory study of the performance of residential air-to-air heat exchangers during operation with freezing and periodic defrosts, freezing caused the temperature efficiency of a cross-flow heat exchanger to decrease at a rate ranging from 1.5 to 13.2 percentage points per hour. Much smaller rates of decrease in temperature efficiency, 0.6 to 2.0 percentage points per hour, occurred during tests with a counterflow heat exchanger. The rate of decrease in efficiency depended on the airstream temperatures and humidities and the duration of the period of freezing. The amount of time required to defrost the heat exchanger's core was 6 to 26% of the total operating time. The average temperature efficiency for freeze-defrost cycles ranged from 48 to 64% in tests of the cross-flow exchanger and 70 to 82% in tests of the counterflow exchanger. When the frequency and duration of defrosts were nearly optimal, approximately a 10 to 15 percentage point decrease in average temperature efficiency was attributed to the freezing and required defrosts. The results suggested that the rate of performance deterioration due to freezing can be reduced by avoiding small airflow passages that can easily be plugged with ice and by designing the exchanger so that condensedmore » water does not drain toward the cold regions of the core. Based on this investigation, suggestions are made for future experimental studies of freezing and for improved control of freeze-protection systems. 1 reference, 8 figures, 2 tables.« less
Authors: W.J. Fisk, K. Archer, R. Chant, D. Hekmat, Francis J. Offermann, Brian S. Pedersen
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Funder: U.S. Department of Energy
Awards: G1398330795, G1643223109, G193590374
OpenAlex ID: W1494269202