Chiller for Constant Temperature and Pressure Testing of Battery Packs

New energy vehicle cooling system (water-cooled/liquid chiller)Test items:
1. Test the head and flow rate of the water pump to obtain the flow rate and head characteristic curve of the water pump;
2. It is possible to test the water pump flow rate during the actual use of the vehicle.
3. It is possible to test the heat dissipation characteristics of the radiator to obtain the heat dissipation characteristics of the radiator.
4. Output the temperature characteristic curves of each typical position.
With the development of new energy power batteries, the development of high-density, high-power, fast-charging and discharging new energy vehicles is encouraged. The original air-cooled heat dissipation method used in new energy vehicles can no longer solve the battery heat dissipation problem. The advantages of the liquid cooling system are fast cooling rate, good temperature uniformity, simple fluid (temperature and flow rate) control, etc. The liquid cooling system has become an inevitable trend for new energy vehicles. The thermal management system of the whole vehicle needs to be redesigned.
At present, there is a lack of operating data for the liquid cooling and heat dissipation system of the battery pack (PACK), so new energy vehicle manufacturers are unable to design the liquid cooling system of the whole vehicle. Vehicle manufacturers need to know the following data: 1) The reasonable temperature of the battery pack is10 - 30°C.In low-temperature weather, the liquid cooling system may reach - 30°C. There is a heating element inside the battery pack to preheat before startup to perform a thermal protection function. When the battery temperature exceeds 30°C during vehicle driving, it is necessary to cool down through the - 30°C liquid cooling system. At this time, the flow rate of the liquid is required? *** The battery temperature is controlled within the range of 10 - 30°C. Since the pipe diameter of the vehicle liquid cooling system is fixed, it is necessary to adjust the pressure to control the flow rate. By analogy, as the temperature of the vehicle coolant changes, in order to *** the battery temperature, the flow rate and pressure of the coolant also need to change. 2) In high-temperature weather, the temperature of the vehicle coolant and the battery pack may reach above 50°C. What is the charging and discharging condition of the battery pack? The cooling capacity of the vehicle refrigeration system (cooling the interior space of the vehicle air conditioner, the battery pack, the electric drive, and the engine liquid cooling system) needs to be matched so that the thermal management of the whole vehicle can reach a rapid balance. Ensure that the performance and safety of the whole vehicle are within a reasonable range. The above data requires the liquid cooling thermal test platform of Shenzhen Chuanbenster Refrigeration Equipment Co., Ltd. to provide *** data.

Thermal-related issues of batteries are the key factors determining their performance, safety, lifespan, and *** of use. Firstly, the temperature level of lithium-ion batteries directly affects their energy and power performance during use. When the temperature is relatively low, the available capacity of the battery will decline rapidly. Charging the battery at too low a temperature (such as below 0°C) may cause an instantaneous overvoltage charging phenomenon, resulting in internal lithium precipitation and further triggering a short circuit. Secondly, thermal-related issues of lithium-ion batteries directly affect the safety of the batteries. Defects in the production and manufacturing process or improper operations during use may cause local overheating of the battery, and then trigger a chain exothermic reaction, *** ultimately resulting in serious thermal runaway events such as smoking, fire, and even explosion, threatening the lives of vehicle occupants. In addition, the working or storage temperature of lithium-ion batteries affects their service life. The suitable temperature of the battery is approximately between 10 and 30°C. Temperatures that are too high or too low will cause a relatively fast decline in the battery life. The large size of power batteries makes the ratio of their surface area to volume relatively small, and it is not easy for the heat inside the battery to dissipate. There are more likely problems such as uneven internal temperature and excessive local temperature rise, which will further accelerate the battery decline, shorten the battery life, and increase the total ownership *** of users.

The battery thermal management system is one of the key technologies to address thermal-related issues of batteries and improve the performance, safety, and lifespan of power batteries.

The main functions of the thermal management system include:

● Effectively dissipate heat when the battery temperature is high to prevent thermal runaway accidents;

● Preheat when the battery temperature is low to increase the battery temperature and ensure the charging, discharging performance, and safety at low temperatures;

● Reduce the temperature difference within the battery pack, inhibit the formation of local hot spots, prevent the rapid degradation of batteries at high-temperature positions, and extend the overall lifespan of the battery pack.

The temperature environment inside the battery pack (PACK) has a great impact on the reliability, lifespan, and performance of the battery cells. Therefore, it is particularly important to maintain the temperature inside the PACK within a certain range. This is mainly achieved through cooling and heating. Here, we will briefly introduce three cooling methods: air cooling, liquid cooling, and direct cooling.

Air Cooling

Air cooling is a heat dissipation method that uses low-temperature air as the medium and the convection of heat to lower the battery temperature. It is divided into natural cooling and forced cooling (using a fan, etc.). This technology uses natural wind or a fan, combined with the evaporator built into the vehicle, to cool the battery. The system has a simple structure and is easy to maintain. It was widely used in early electric passenger vehicles, such as the Nissan Leaf and Kia Soul EV, and is also commonly adopted in current electric buses and electric logistics vehicles.

Liquid Cooling

Liquid cooling technology uses the convective heat transfer of a liquid to carry away the heat generated by the battery and lower the battery temperature. The liquid medium has a high heat transfer coefficient, large heat capacity, and fast cooling speed, which is very effective in reducing high temperatures and improving the uniformity of the battery pack temperature field. At the same time, the volume of the thermal management system is relatively small. The form of the liquid cooling system is relatively flexible: the battery cells or modules can be immersed in the liquid, cooling channels can be set between the battery modules, or a cooling plate can be used at the bottom of the battery. When the battery is in direct contact with the liquid, the liquid must be highly insulating (such as mineral oil) to avoid short circuits. At the same time, the airtightness requirements of the liquid cooling system are also relatively high. In addition, there are requirements for mechanical strength, vibration resistance, and lifespan.

Liquid cooling is the preferred solution for many current electric passenger vehicles. Typical products at home and abroad include the BMW i3, Tesla, Chevrolet Volt, BMW Zinoro, and Geely Emgrand EV.

Direct Cooling

Direct cooling (direct cooling with refrigerant): Using the principle of the latent heat of evaporation of the refrigerant (such as R134a), an air conditioning system is established in the vehicle or battery system. The evaporator of the air conditioning system is installed in the battery system. The refrigerant evaporates in the evaporator and quickly and efficiently carries away the heat of the battery system, thus completing the cooling operation of the battery system.

At present, the direct cooling method is basically used in electric passenger vehicles. A typical example is the BMW i3 (the i3 has two cooling solutions: liquid cooling and direct cooling).

Cooling system temperature: -40 to 80 degrees Celsius, accuracy ±0.3

Cooling medium flow rate: 0 - 100 L/min, accuracy ±3%

Fluid circulation pressure: 0 - 7 Mpa, accuracy 0.01 Mpa

The new energy battery cooling system test platform (liquid cooling, water cooling) is mainly used for the stability test of the water cooling systems of new products such as electric drives, motors, reducers, and charging piles of new energy vehicles. Constant temperature, constant pressure and constant current thermal tests (5 - 85 degrees Celsius), high and low temperature operation tests (150 to -40 °C), motor cooling water system (5 - 30 °C) and other cooling tests. The application scope includes electric vehicles, hybrid vehicles, aerospace, and scientific research. The dynamometer is designed with water cooling as the standard. Some users have oil-cooled and air-cooled types. Shenzhen Chuanbenster Refrigeration Equipment Co., Ltd. focuses on the development, design, manufacturing and sales of equipment cooling systems. According to the user requirements of thermal conductive materials, thermal insulation, heat preservation materials, radiators, etc., this machine is applicable to the above industries.