A computer simulation program was developed to investigate the effects of frost deposited on the outdoor coil of air-to-air heat pumps. Three methods of defrost initiation were investigated. These were based on (1) air pressure drop across the coil, (2) combination air temperature and compressor run time, and (3) combination of evaporator temperature and compressor run time. The values of the setpoints for defrost initiation were varied to determine their effect on the amount of frost collected and the number of daily defrosts at different ambient temperatures and relative humidities. A residence with typical quantities of insulation, glass, and roof area was used to generate heating and cooling loads for the appropriately selected heat pump.
The simulation showed that the amount of frost collected was independent of the method or the setpoint of defrost initiation. From an energy point of view as well as number of annual defrosts, the demand defrost technique appears to be the best criteria for defrost initiation.
Units: I-P
Citation: Symposium, ASHRAE Transactions, 1986, vol. 92, pt. 1B, San Francisco
Product Details
- Published:
- 1986
- Number of Pages:
- 16
- File Size:
- 1 file , 1.5 MB
- Product Code(s):
- D-SF-86-17-2
