A study of the transient behavior during start-up of residential heat pumps
A series of tests were performed to study and characterize the transient sensible and dehumidification performance of a heat pump in the cooling mode. The effects of indoor dry-bulb temperature (72 to 80 F), indoor relative humidity (20 to 67%), outdoor dry-bulb temperature (82 to 100 F), cycling rate (0.8 to 10 cph) and percent ON-time (20 to 95%) on the transient performance (sensible and latent capacity, efficiency and sensible heat ratio) are addressed in this study. The results indicated that part load factor (PFL) can be as low as 0.65 at low percent ON-times and high cycling rates. The combination of low percent ON-times and high cycling rates produced maximum cyclic losses. The dehumidification process usually started between 60 to 150 seconds after start-up depending on the indoor ambient conditions, percent ON-time and cycling rate. The sensible and latent capacity response and part load efficiency of the heat pump increased with an increase in indoor relative humidity. There was a slight increase in PLF with indoor dry-bulb temperature. The outdoor dry-bulb temperature did not have any effect on the transient performance. Based on the functional relationship of PLF and coefficient of degradation (C{sub D}) with the five independent variables a multiple linear regression analysis was performed on the experimental data. The analysis yielded two general equations to predict PLF and C{sub D}. A lumped parameter heat pump transient analysis computer model was developed. The model was capable of simulating the transient response of a vapor compression air-to-air heat pump commonly used in residential applications. The simulated results were in good agreement with the laboratory results at high percent ON-times (>20) and high relative humidities (>45).
- Research Organization:
- Texas A and M Univ., College Station, TX (USA)
- OSTI ID:
- 6413852
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HEAT PUMPS
START-UP
TRANSIENTS
AIR CONDITIONING
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DEHUMIDIFICATION
EFFICIENCY
EQUATIONS
FORECASTING
HEAT TRANSFER
HUMIDITY
LOSSES
MATHEMATICAL MODELS
OPERATION
PERFORMANCE
REGRESSION ANALYSIS
RESIDENTIAL SECTOR
RESPONSE FUNCTIONS
TEMPERATURE DEPENDENCE
VAPOR COMPRESSION REFRIGERATION CYCLE
ENERGY TRANSFER
FUNCTIONS
MATHEMATICS
SIMULATION
STATISTICS
320106* - Energy Conservation
Consumption
& Utilization- Building Equipment- (1987-)