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ABSTRACT
ASHP system is extensively applied to maintain indoor thermal environment but contributes to high building energy consumption. Better energy efficiency is possible through cooling performance improvements. This study investigates, using full-scale experiments, the cooling performance of ASHP. In the series of experiments, we vary the major influencing factors—evaporator inlet air temperature, air velocity, and compressor frequency and measured their impacts on response variables that include cooling capacity, compressor power, and the COP. The design of experiment (DOE) approach is used to plan and analyze the experiments. The results show that cooling capacity of ASHP system significantly increases with the rising evaporator inlet air temperature, air velocity, and compressor frequency. However, because of increasing fan and compressor power with rising air velocity and compressor frequency, COP dramatically decrease. Finally, the study of develop a simple predictive model for assessing the COP of ASHP. Comparing with the predicted and experimental results shows an agreement within 10% deviation, which indicates the suitability of the prediction model. Therefore, a predictive model can help system operators to set the optimal design parameters for achieving optimal COP performance of ASHP system.
Nomenclature
| HVAC | = | Heating, ventilation, and air conditioning |
| ASHP | = | Air Source Heat Pump |
| COP | = | Coefficient of performance |
| GWP | = | Global warming potential |
| AAC | = | Automotive air conditioning |
| FCC | = | Fixed capacity compressor |
| VCC | = | Variable capacity compressor |
| HPC | = | Head pressure control |
| DOE | = | Design of Experiment |
| RSM | = | Response surface methodology |
| = | Heat transfer rate | |
| = | System power (W) | |
| c | = | Specific heat of water (J/(kg.°C)) |
| y | = | Response parameter |
| = | Coefficient | |
| x | = | Design parameter |
| = | Mass flow rate of air (kg/s) | |
| i | = | Enthalpy of air (kJ/kg) |
| V | = | Air velocity (m/s) |
| F | = | Frequency of compressor |
| T | = | Air temperature |
Subscripts
| a | = | Air |
| w | = | Water |
| p | = | Compressor |
| in | = | Inlet |
| out | = | Outlet |
| c | = | Condenser |
| e | = | Evaporator |
| o | = | Order number |
| j | = | Order number |
| h | = | Order number |
| q | = | Order number |