Heat exchanger for motor cooling device of new energy vehicle
The heat exchanger in the motor cooling device of new energy vehicle is relatively important in the operation of the entire motor cooling device of new energy vehicle, so it is necessary for us to understand the heat exchanger of the motor cooling device of new energy vehicle.
The shell and tube heat exchanger in the motor cooling device of new energy vehicle consists of a shell, a heat transfer tube bundle, a tube sheet, a baffle (baffle) and a tube box. The shell is mostly cylindrical, with a tube bundle inside, and both ends of the tube bundle are fixed on the tube sheet.
The two hot and cold fluids for heat exchange, one flows in the tube, called the tube-side fluid, and the other flows outside the tube, called the shell-side fluid. In order to improve the heat transfer coefficient of the fluid outside the tube, several baffles are usually installed in the shell. The baffle can increase the shell-side fluid velocity, forcing the fluid to pass through the tube bundle horizontally for multiple times according to the specified distance, and enhancing the turbulence of the fluid. The heat exchange tubes can be arranged in an equilateral triangle or a square on the tube sheet. The equilateral triangle arrangement is more compact, the turbulence of the fluid outside the tube is high, and the heat transfer coefficient is large; the square arrangement is convenient for cleaning the outside of the tube, which is suitable for fluids that are prone to scaling.
The shell and tube heat exchanger of the motor cooling device of new energy vehicles has different temperatures of the fluid inside and outside the tube, so the temperature of the shell and tube bundle of the heat exchanger is also different. If the two temperatures differ greatly, a large thermal stress will be generated in the heat exchanger, causing the tube to bend, break, or pull off the tube sheet. Therefore, when the temperature difference between the tube bundle and the shell exceeds 50°C, appropriate compensation measures must be taken to eliminate or reduce thermal stress. Generally speaking, the shell and tube heat exchanger of the motor cooling device of new energy vehicles can be divided into the following main types:
The tube sheets at both ends of the tube bundle of the fixed tube sheet heat exchanger of the motor cooling device of new energy vehicles are integrated with the shell, and the structure is simple, but it is only suitable for heat exchange operations when the temperature difference between the cold and hot fluids is not large and the shell side does not require mechanical cleaning. When the temperature difference is slightly large and the shell side pressure is not too high, an elastic compensation ring can be installed on the shell to reduce thermal stress.
The tube sheet at one end of the tube bundle of the floating head heat exchanger of the motor cooling device of new energy vehicles can float freely, completely eliminating thermal stress; and the entire tube bundle can be pulled out of the shell, which is convenient for mechanical cleaning and maintenance. Floating head heat exchangers are widely used, but their structure is relatively complex and their cost is high.
U-tube heat exchanger for motor cooling device of new energy vehicle Each heat exchange tube is bent into a U shape, and the two ends are fixed to the upper and lower areas of the same tube sheet, and are divided into inlet and outlet chambers by the partition in the tube box. This type of heat exchanger completely eliminates thermal stress, and its structure is simpler than the floating head type, but the tube path is not easy to clean.
Stuffing box heat exchanger for motor cooling device of new energy vehicle The structural feature of the stuffing box heat exchanger is that only one end of the tube sheet is fixedly connected to the shell, and the other end is sealed with a stuffing box. The tube bundle can be freely extended and retracted, and no temperature difference stress caused by the temperature difference between the shell wall and the tube wall will be generated.
The structural feature of the kettle heat exchanger for motor cooling device of new energy vehicle is that an appropriate evaporation space is set on the upper part of the shell, and it also serves as a steam chamber. The tube bundle can be fixed tube sheet type, floating head type or U-tube type. The kettle heat exchanger is easy to clean and maintain, can handle unclean and easy-to-scale media, and can withstand high temperature and high pressure. It is suitable for liquid-steam heat exchange and can be used as a waste heat boiler with a simple structure.
There are also various heat exchangers for the motor cooling device of new energy vehicles, and we need to screen different models and types.
