Thermal challenge of Energy Storage
The temperature control focus of electrochemical energy storage is to improve the service life and safety of batteries, so the space restrictions on temperature control equipment are relatively relaxed. Usually, electrochemical energy storage devices are deployed in outdoor environments, so more attention is paid to the stability, service life, and operation and maintenance costs of temperature control equipment. The requirements for the volume and weight of the equipment are relatively loose. At present, air-cooled solutions account for a large proportion of electrochemical energy storage, but with the upgrading of new energy power stations and off grid energy storage towards larger battery capacity and higher system power density, the use of liquid cooling solutions will also rapidly increase.
The temperature control demand of new energy vehicles places more emphasis on improving the thermal management efficiency and temperature control accuracy in fixed spaces. In addition to temperature control of the battery, new energy vehicles also require temperature control of the electronic control system, motor, and cabin. Due to the higher energy density of power batteries and limited body space, the thermal management of new energy vehicles requires higher requirements for volume, weight, heat dissipation efficiency, and temperature control accuracy.
The temperature control requirements of data centers aim to increase cooling power and reduce the power utilization efficiency of data centers (PUE=total equipment energy consumption of data centers/IT equipment energy consumption). With the improvement of artificial intelligence chip computing power, the power consumption of data centers has significantly increased. Therefore, IDC temperature control emphasizes the need for heat dissipation efficiency to keep up with the speed of chip power consumption improvement. Against the backdrop of tightening PUE policies, the efficiency of thermal management needs to be further improved, and immersion and spray liquid cooling cooling solution need to be further promoted.
The increase in charge discharge ratio is a trend in the development of electrochemical energy storage, and the demand for thermal management in energy storage will also become higher. Energy storage batteries with higher charge discharge ratios will have a faster risk of thermal runaway. Therefore, the heat transfer efficiency of energy storage thermal management also needs to be further improved. In terms of heat transfer efficiency, due to the higher specific heat capacity and thermal conductivity of liquids compared to gases, and the closer to the heat source, the higher the cooling efficiency. Under the same power consumption, the heat dissipation temperature of liquid cooled battery packs is 3-5 ℃ lower than that of air-cooled ones; And the liquid cooling scheme does not require the design of air ducts, which can greatly save land area, so replacing air cooling with liquid cooling will also become a future trend.
Air cooling will gradually be replaced by liquid cooling, and immersion liquid cooling has the possibility of further increasing penetration rate as the price of coolant decreases. External thermal management with container as the thermal management goal may be an attempt direction for further cost reduction in thermal management solutions. In liquid cooling technology, cold plate liquid cooling and immersion liquid cooling are two common forms. There are various solutions for liquid cooling, among which the mainstream and efficient solutions include immersion liquid cooling, spray cooling, and cold plate liquid cooling. Immersion liquid cooling has better performance, including single-phase/phase change cooling, but requires higher thermal and physical properties, stability, material compatibility, and insulation of the coolant, resulting in higher costs. At present, cold plate liquid cooling is a relatively mature liquid cooling solution, with simple installation, good material compatibility, low transformation cost, fast development speed, and lower price than immersion liquid cooling.
The possible development trends of future thermal management include:
1. Air cooling will be replaced by liquid cooling,
2. The development of cold plate type towards immersion type,
3. Externalization of thermal management. With the continuous improvement of chip computing power, battery energy density, and charging and discharging efficiency, the heat generated per unit time by equipment will also increase significantly. Therefore, improving the heat exchange efficiency of temperature control systems will become the trend of industry development.
