Heat pumps are used in many applications, both in households and industries, for space air conditioning and hot water provision. The calorimeter is the equipment used in testing the heat pump system to obtain performance data. In the conventional testing mode and under standard conditions, the calorimeter utilizes a lot of energy through refrigeration and heating systems. In this study, a newly developed calorimeter with a heat recovery unit was used to test the performance of a water-to-water heat pump system. The aim was to minimize the rate of energy used in the conventional calorimeter. Two heat recovery control methods were adopted. In the control (1), the heat recovery unit was used to control the inlet water temperature setpoint for the heat pump indoor heat exchanger, whereas in control (2), the heat recovery unit was used to control the inlet water temperature setpoint for the heat pump outdoor heat exchanger. Tests were executed by varying the operating mode and test conditions. For the heating operating mode, the inlet water setpoint temperatures for the indoor and outdoor heat pump heat exchangers were 40 °C and 5 °C, respectively, whereas for the cooling mode, the inlet water setpoint temperatures for the outdoor and indoor heat pump heat exchangers were 25 °C and 12 °C, respectively. The analyses of the experimental results revealed that the energy saving of the calorimeter with heat recovery was about 71% in cooling mode and 73% in heating mode compared to the conventional calorimeter. Also, the energy consumption of the proposed calorimeter was analyzed based on the control methods. In heating mode, the calorimeter performance was enhanced when the control (2) strategy was used because the energy saving was about 8 to 13% compared to control (1). However, in the cooling mode test, it was the control (1) method that resulted in energy savings of about 6.4 to 21% compared to the control (2) method.
Development and verification of control system for heat recovery ground source heat pump system
