Thermal Energy Storage Systems
Based on the type of thermal storage medium, these systems can be broadly classified into water thermal storage systems, ice thermal storage systems, and eutectic salt thermal storage systems.
Air Source Heat Pump:
In summer, the indoor evaporator absorbs the cooling load of the room and releases heat to the outdoor air; in winter, the four-way reversing valve of the unit reverses the flow, the outdoor heat exchanger absorbs heat from the air, and the indoor heat exchanger releases heat to the room for heating.
Features:
Easy to use and widely applicable;
Frosting occurs on the unit in winter, leading to a decrease in heat pump performance;
There is a mismatch between the heat output of the heat pump and the heating requirements of the building, usually requiring an auxiliary heat source.
Water Source Heat Pump:
In summer, the indoor evaporator absorbs the cooling load of the room, and the heat generated by the cooling load and compressor work is discharged into the water source through the condenser; in winter, the four-way reversing valve of the unit reverses the flow, the outdoor heat exchanger absorbs heat from the water source, and the indoor heat exchanger releases heat to the room for heating.
Features:
Water temperature is stable and generally higher than the outdoor air;
Groundwater, surface water, or industrial wastewater quality needs to be treated;
Reinjection technology is challenging.
Ground Source Heat Pump:
Through the flow of circulating fluid in the buried pipe heat exchanger, heat is transferred to the ground (summer), or heat is absorbed from the ground (soil) (winter), while the four-way reversing valve is used to switch between cooling and heating of the room.
Features:
Ground temperature fluctuations are small and delayed, resulting in good operating conditions for the unit;
In cases where the cooling and heating loads are unequal in summer and winter, there may be year-to-year changes in soil temperature;
The thermal conductivity of the soil is low, requiring a large soil heat exchanger area.
