Application and reliability of heat pump in energy storage system
The main temperature control modes of energy storage system are air-cooled and liquid-cooled. The air-cooling scheme uses air as the cooling medium, which is direct and simple, but the heat dissipation efficiency is medium and not very high. Basic applications in communication base stations, small-scale ground power stations, such as low power density, heat production rate of small projects.
The liquid cooling scheme is divided into cold plate and immersion type. The cold plate type adopts water, ethylene glycol and other cooling fluids, and the heat is dissipated by the direct contact between the guide groove and the electric core distributed evenly on the liquid cooling plate. The immersion type immerses the battery in the insulating cooling oil for cooling and heat dissipation. Cooling efficiency is relatively high, suitable for power cell, 100 MW level large capacity energy storage power plant, data center and other scenarios.
Application of heat pump in energy storage system
In low temperature environment, electric heating is used to raise the temperature of the energy storage system, and the heat pump can replace the electric heating device to provide a stable temperature scene for the battery and ensure the high charging and discharging efficiency of the battery, reduces the rate at which battery capacity decays. At the same time, the heat pump provides temperature and humidity control for the whole environment of the energy storage container, ensuring that the temperature and humidity of the energy storage battery are stable no matter the environment temperature is high or low.
At present, there is no clear standard for the safety and performance of heat pump in energy storage system. At present, it is the standard of common water chillers and household air-conditioners.
Application quality requirements of heat pump in energy storage system
Due to close contact with the battery, it will be subject to very large electromagnetic interference, therefore, the quality requirements of heat pump system include lightning surge immunity, electrical fast transient pulse immunity, voltage sag, short-time interruption and voltage variation immunity, harmonic immunity, electrostatic immunity, radio frequency electromagnetic field immunity, power frequency magnetic field immunity, pulse magnetic field immunity, conduction immunity, radiation immunity and conduction immunity of radio frequency induction.
At the same time, the heat pump system needs to have better environmental tolerance, usually the use of energy storage plant environment is poor, heat pump needs wind and sand environment adaptability, light aging environment adaptability, damp and heat environment adaptability, high and Low Temperature Environment Adaptability, salt spray corrosion environment adaptability, Plateau Environment Adaptability.
Wind, sand, light environment
Damage system components in wind and sand environment, reduce refrigeration capacity, increase energy consumption. In the light environment, plastics, coatings, rubber and other materials will have discoloration, color change, luster, crack, blistering, embrittlement, oxidation and other problems.
Damp heat, high and low temperature environment
In the hot and humid environment, the electrical insulation decreases, the leakage current increases, and the operating temperature of the system increases. High and low temperature environment, high and low temperature system operating temperature rise, low temperature rubber seals performance decline, high and low temperature environment performance decline.
Salt fog corrosion environment in coastal area
In salt spray corrosion environment, there are fin corrosion, capacity reduction, parts corrosion, sensor failure, grounding and structure fall off danger, circuit failure danger, performance degradation.
Electric insulation and heating environment in Plateau area
In plateau environment, with the decrease of atmospheric pressure and breakdown voltage, the electrical insulation failure is more easily. At the same time, at an altitude of 4,500 m, every 1,000 m rise means a decrease of 7.7-10.5 KPA in average air pressure and a 3-10% increase in temperature.
The requirements of the coolant should have low corrosion, low conductivity, long service life and good cooling effect. HCFC and HFCS refrigerants are Montreal Protocol to be replaced. Energy storage heat management systems need to find safe and efficient refrigerants, and most of the environment-friendly refrigerants are flammable refrigerants, need to focus on the safety issues.
