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Characteristics of plate heat exchanger
Release time:
2022-08-18
The working pressure should not be too large, which may cause air leakage; The plates of plate heat exchanger are sealed with sealing gasket.
Characteristics of plate heat exchanger
Because different corrugated plates are inverted each other, forming a complex flow channel, making the fluid flow in the flow channel between the corrugated plates in a rotating three-dimensional way, and can generate turbulence at low Reynolds number (generally Re=50~200), so the heat transfer coefficient is high, which is generally considered to be 3~5 times of the shell. The logarithmic average temperature difference is large, and the terminal temperature difference is small.
In the shell-and-tube heat exchanger, the two kinds of fluids flow in the tube side and the shell side respectively, which are cross-flow on the whole, and the logarithmic average temperature difference correction coefficient is small, while the plate heat exchanger plates are mostly in the mode of sum flow or countercurrent flow, and the correction coefficient is usually about 0.95. In addition, the flow of hot and cold fluids in the plate heat exchanger plates is parallel to the heat exchange surface, and there is no side flow. Therefore, the temperature difference at the end of the plate heat exchanger plates is small, and the heat exchange of water can be less than 1 ℃, The shell-and-tube heat exchanger is generally 5 ℃ FFF. C. Small footprint. The plate heat exchanger has a compact structure. The heat exchange area per unit volume is 2~5 times that of the shell-and-tube heat exchanger, and unlike the shell-and-tube heat exchanger, the tube bundle is reserved for maintenance. Therefore, to achieve the same heat exchange, the plate heat exchanger covers an area of about 1/5~1/8 of the shell-and-tube heat exchanger.
Easy to change heat transfer area or process combination; As long as several plates are added or reduced, the purpose of increasing or reducing the heat exchange area can be achieved; The required process combination can be achieved by changing the arrangement of plates or replacing several plates to adapt to the new heat exchange conditions, while the heat exchange area of shell-and-tube heat exchanger is almost impossible to increase. Light weight; The plate thickness of plate heat exchanger is only 0.4~0.8mm, and the heat exchange tube thickness of shell-and-tube heat exchanger is 2.0~2.5mm. The shell of shell-and-tube heat exchanger is much heavier than the frame of plate heat exchanger, while the plate of plate heat exchanger is generally only about 1/5 of the shell and tube weight.
Low price; With the same materials and the same heat exchange area, the plate price of plate heat exchanger is about 40%~60% lower than that of shell-and-tube heat exchanger. Simple production; The heat transfer plate of the plate heat exchanger is processed by stamping, which is highly standardized and can be produced in large quantities. Shell-and-tube heat exchangers are generally made by hand. Easy to clean; As long as the pressure bolt is loosened, the plate bundle can be loosened and the plate can be removed for mechanical cleaning, which is very convenient for the heat transfer process of equipment requiring frequent cleaning. 1、 Low heat loss; Only the shell plate of the heat transfer plate of the plate heat exchanger is exposed to the atmosphere, so the heat loss can be ignored, and no thermal insulation measures need to be taken. However, shell-and-tube heat exchangers have large heat loss and need insulation layer. Small capacity; About 10%~20% of the shell-and-tube heat exchanger. Large pressure loss per unit length; Because the gap between the heat exchange surfaces is small and the heat exchange surfaces are concave and convex, the pressure loss is greater than that of the traditional smooth tube. Not easy to zoom; Due to sufficient internal turbulence, the expansion coefficient is only 1/3~1/10 of that of shell-and-tube heat exchanger.
The working pressure should not be too large, which may cause air leakage; The plates of plate heat exchanger are sealed with sealing gasket. Generally, the working pressure shall not exceed 2.5 mpa, and the medium temperature shall be below 250 ℃, otherwise leakage may occur. Easy to block; Because the channel between plates is very narrow, generally only 2~5mm, when the heat exchange medium contains large particles or fiber materials, it is easy to block the channel between plates.
