Abstract:
The study aimed to compare the coefficient of performance (COP) under different
conditions and to investigate the relationship among parameters that affects the performance of the
heat pump. The paper presents the research results of parameters effecting the performance of a
550 L water heater by 16 kW heat pump using R-134a refrigerant. The heat pump heated water from
initial temperature (30 degree Celsius) to the set temperature (65 degree Celsius) at the condenser outlet.
In testing room, the parameters were controlled and varied based on conditions of
experiment. The data were collected from the experiment by varying the parameters. The refrigerant
mass flow rate (𝑚̇[subscript r] ) varies at 0.0589, 0.0751 and 0.0837 kg/s. The water mass flow rate (𝑚̇ [subscript W]) varies at 0.13, 0.23 and 0.32 kg/s. The air temperature at inlet evaporator ([subscript a] ) varies at 25, 30 and 35 degree Celsius.
The experimental data were analyzed and the coefficient of performance (COP) was compared.
The results reveal that the associated parameters affecting the COP are the refrigerant mass
flow rate (𝑚̇[subscript r] ), the water mass flow rate (𝑚̇[subscript W]), the air temperature at inlet evaporator (𝑇[subscript a]) and the water temperature at inlet condenser (𝑇[subscript w], [subscript j] ). Regarding the overall associated parameters, the COP
varied directly with the refrigerant mass flow rate (𝑚̇[subscript r]), the water mass flow rate (𝑚̇[subscript W] ) and the air temperature at inlet evaporator (𝑇[subscript a]). On the other hand, the COP varied inversely with the water temperature at inlet condenser ([subscript W], [subscript j]). In addition, these results can be applied to control heat pumps having the highest COP for saving energy and used as a guideline for developing saving energy heat pump water heater systems in the future.