a. High heat transfer coefficient Because different corrugated plates are inverted, they form a complex flow channel, which makes the fluid rotate three-dimensionally in the flow channel between corrugated plates, which can be generated at a low Reynolds number (generally Re = 50 ~ 200). Turbulent flow, so the heat transfer coefficient is high, generally considered to be 3 to 5 times the shell and tube type.
b. Large logarithmic average temperature difference, small end temperature difference In the shell and tube heat exchanger, the two fluids flow in the tube and shell side respectively, and are generally cross-flow flow. The logarithmic average temperature difference correction coefficient is small, and the plate type Heat exchangers are mostly co-current or counter-current, and their correction factors are usually around 0.95. In addition, the flow of cold and hot fluids in the plate heat exchanger is parallel to the heat exchange surface and there is no side flow, so the plate heat exchange is made. The temperature difference at the end of the device is small, and the heat transfer to water can be lower than 1 ℃, while the shell and tube heat exchanger is generally 5 ℃ fff.
c. The small plate heat exchanger has a compact structure, and the heat exchange area per unit volume is 2 to 5 times that of the shell and tube type. It is also not necessary to reserve a maintenance site for drawing out the tube bundle like the shell and tube type. Heat exchange capacity, the area of the plate heat exchanger is about 1/5 ~ 1/8 of the shell and tube heat exchanger.
d. It is easy to change the heat exchange area or process combination. As long as a few plates are added or removed, the purpose of increasing or reducing the heat exchange area can be achieved; changing the plate arrangement or replacing several plates can achieve the required process combination. To adapt to the new heat exchange conditions, and the heat transfer area of the shell and tube heat exchanger is almost impossible to increase.
e. Light weight plate heat exchanger has a plate thickness of only 0.4 ~ 0.8mm, while the thickness of the heat exchange tube of the shell and tube heat exchanger is 2.0 ~ 2.5mm. The frame is much heavier, and the plate heat exchanger is generally only about 1/5 of the shell and tube weight.
f. Low price With the same material and the same heat exchange area, the price of plate heat exchanger is about 40% ~ 60% lower than that of shell and tube type.
g. Easy to make The heat transfer plate of the plate heat exchanger is stamped, has a high degree of standardization, and can be produced in large quantities. The shell and tube heat exchanger is generally made by hand.
h. Easy to clean The frame plate heat exchanger can loosen the plate bundle as long as the compression bolts are loosened, and remove the plates for mechanical cleaning. This is very convenient for the heat exchange process that requires frequent cleaning of the equipment.
i. Small heat loss Only the shell plate of the heat transfer plate is exposed to the atmosphere, so the heat loss is negligible, and no thermal insulation measures are required. The shell-and-tube heat exchanger has a large heat loss and requires a heat insulation layer.
j. Small capacity is 10% ~ 20% of shell and tube heat exchanger.
k. Large pressure loss per unit length Because the gap between the heat transfer surfaces is small and the heat transfer surfaces have irregularities, the pressure loss is greater than that of a traditional smooth tube.
l. Not easy to scale Due to the internal turbulence, it is not easy to scale. Its scale factor is only 1/3 ~ 1/10 of the shell and tube heat exchanger.
m. The working pressure should not be too high, the temperature of the medium should not be too high, and it may leak. The plate heat exchanger should be sealed with a gasket. The working pressure should generally not exceed 2.5 MPa.
n. Easy to block Due to the narrow channel between the plates, it is generally only 2 ~ 5mm. When the heat exchange medium contains large particles or fibrous substances, it is easy to block the channel between the plates.