1. The heat transfer coefficient.
Plate heat exchanger due to the different corrugated plate upside down each other, constitute a complex flow, make the fluid in the flow passage between corrugated plate revolved and three dimensional flow in a relatively low Reynolds number (Re = 50 ~ 200) under turbulent, so the heat transfer coefficient is high, generally considered the tube shell type 3 ~ 5 times.
2. The logarithmic mean temperature difference is big, the terminal temperature difference is small.
In tube and shell heat exchanger, two kinds of fluid flow in tube side and shell side, respectively, on the whole is wrong flow, logarithmic mean temperature difference correction coefficient is small, and the plate heat exchanger is more and flow or countercurrent flow mode, the correction coefficient is usually at around 0.95, in addition, cold and hot fluid flow in the plate heat exchanger is parallel to the heat transfer surface, no side stream, thus makes the plate heat exchanger at the end of the temperature difference is small, the water heat exchanger can be less than 1 ℃, shell and tube heat exchanger is usually 5 ℃.
3. The cover an area of an area.
Per unit volume of plate heat exchanger structure is compact, so the heat exchange area of tube and shell of 2 ~ 5 times, also don't like tube shell type want to reserve a spare tube bundle service place, so for the same in heat, plate heat exchanger which covers an area of about 1/5 ~ 1/8 of tube and shell heat exchanger.
4. Change the heat transfer area or process combination.
Increase or decrease as long as a few sheets of plate of plate heat exchanger, can achieve the purpose of increase or decrease heat exchange area;
Change of plates or replace a few pieces of plate, can achieve the required process combination, adapt to the new working condition of heat transfer, shell and tube heat exchanger heat transfer area is almost impossible to increase.
5. Weight.
The plate thickness of the plate heat exchanger was only about 0.4 ~ 0.8 mm, the thickness of heat exchange tube and tube heat exchanger is 2.0 ~ 2.5 mm, tube and shell of shell much heavier than the framework of plate heat exchanger, plate type heat exchanger generally about 1/5 of the weight of tube and shell.
6. The price.
Using the same material, under the same heat transfer area, prices of plate heat exchanger tube shell type low about 40% ~ 60%.
7. The production process.
Plate heat exchanger heat transfer plate is to use stamping processing, high degree of standardization, and can be mass production, usually use handmade tube heat exchanger.
8. To clean.
Frame type plate heat exchanger as long as the bolt looseness pressure, can loosen plate beam and plate for mechanical cleaning, heat transfer process of the need to constantly cleaning equipment is very convenient.
9. Heat loss.
Plate heat exchanger heat transfer plate only shell plate is exposed to the atmosphere, so the heat loss can be neglected, also do not need to heat preservation measures.
Heat exchanger of shell and tube heat loss is big, need to thermal insulation layer.
10. The pressure loss of per unit length.
Because the gap between the heat transfer surface of plate heat exchanger is small, the heat transfer surface has concave and convex, therefore is bigger than traditional smooth pipe pressure loss.
11. Work pressure, and temperature.
Plate heat exchanger working pressure, the temperature is unfavorable and exorbitant, may damage the seal plate heat exchanger, high working pressure should not be commonly more than 2.5 MPa, medium temperature should be below 250 ℃, otherwise may leak.
12. Jam.
Plate heat exchanger due to the plate between the channel is very narrow, usually only 2 ~ 5 mm, when the heat transfer medium containing larger particles or fiber material, easy to jam between channel, tube and shell heat exchanger can avoid such problems.
