Performance Of Solar Heat Pump Research Articles

Experimental investigation and performance evaluation on a direct expansion solar-air source heat pump system

Solar energy is the most important renewable energy source for achieving carbon neutrality. The problem of steady and efficient operation must be promptly addressed due to the inconsistent and variable nature of solar energy. This research proposes a multifunctional heat pump using the R417A refrigerant, which combines a direct expansion solar heat pump (DXSHP) with an air source heat pump (ASHP), resulting in a direct expansion sola-air source heat pump (DX-S/AS-HP). The system could operate in three modes: combined cooling and heating, domestic water heating, and space heating. The performance of solar heat pump and air source heat pump in different modes was compared, and the switching logic of different modes was developed accordingly, and the performance of the system at different working temperatures was analyzed. The results demonstrate that in combined cooling and heating mode, the system's average comprehension coefficient of performance (COP) could approach 6.0. In DX-SHP mode, the average COP for domestic water heating and space heating is 3.94 and 4.25, respectively, which is greater than the air source heat pump in similar working conditions. Switching from DX-SHP to ASHP for domestic water heating is only necessary when solar irradiation is less than 300 W m − 2, while switching to ASHP for space heating is only necessary when solar irradiation is absent. The greater the working temperature, the lower the COP. While the working temperature has little effect on thermal collecting efficiency.

Experimental Analysis of a Solar Energy Storage Heat Pump System

This paper introduces a novel solar-assisted heat pump system with phase change energy storage and describes the methodology used to analyze the performance of the proposed system. A mathematical model was established for the key parts of the system including solar evaporator, condenser, phase change energy storage tank, and compressor. In parallel to the modelling work, an experimental set-up of the proposed solar energy storage heat pump system was developed. The experimental data showed that the designed system is capable of meeting cold day heating demands in rural areas of Yanbian city located in Jilin province of China. In day-time operation, the solar heat pump system stores excess energy in the energy storage tank for heating purposes. A desired indoor temperature was achieved; the average coefficient of performance of solar heat pump was identified as 4.5, and the system showed a stable performance throughout the day. In night-time operation, the energy stored in the storage tank was released through a liquid-solid change of phase in the employed phase-change material. In this way, the provision of continuous heat for ten hours was ensured within the building, and the desired indoor air conditions were achieved.

Experiment Study on Heating Performance of Solar-Air Source Heat Pump Unit

Ambient temperature has a great impact on heating performance of air source heat pump. Outdoor fin-tube heat exchanger of air source heat pump usually frost on low temperature conditions, which results low operation efficiency and further deterioration. A solar-air heat pump unit was established and outdoor fin-tube heat exchanger of air source heat pump is used jointly by the refrigerant and solar hot water. Running parameters such as outlet temperature of refrigerant, heat capacity and COP of air source heat pumps of composite heat pump units were tested respectively under the standard working conditions and low temperature conditions. The results showed that the performance of solar-heat pump is significantly improved, compared with the single air source heat pump. The effect is more obvious with increasing of the temperature of the solar hot water temperature. Under standard working conditions (ambient temperature 7℃), the unit heat capacity reached 60.9kW、62.9kW和64.5 kW，increased13.4%、17.1%、20.1% respectively and the coefficient of performance also increased 13.9%、17.4%、20% respectively. Under low temperature conditions (ambient temperature -5℃), the unit heat capacity increased16%, 23.3% and 27.6% respectively, up to 49.52kW、52.67kW、54.5kW，and COP also increased 31.2%、38.6%、45.5% with different solar hot water temperature 20°C, 25°C and 30 °C.