What are the respective advantages of plate evaporators and shell-and-tube evaporators, and what are the differences between them?

The purpose is the same, which is to facilitate evaporation; however, the structure must be different. It’s essentially a combination of the advantages and disadvantages of plate heat exchangers and tube heat exchangers; you can find detailed information by searching on Baidu.

Refer to the following differences between heat exchangers: Comparison of plate heat exchangers and shell-and-tube heat exchangers. Plate Heat Exchanger Shell-and-Tube Heat Exchanger Temperature cross-over① Yes No Terminal temperature difference②°C 1 5 Operation with multiple media Yes No Pipeline connections Can be concentrated in one direction Must be arranged in several directions Overall heat transfer coefficient ratio 3-5 1 Equipment weight ratio 1 3-10 Volume of retained liquid Small Large Footprint area 1 2-5 Leak detection Easier to detect at the leak site Internal leaks are difficult to detect Visual inspection Individual plates can be inspected one by one; it is difficult to inspect the tube bundle Time required to open minutes 15-20 60-90 Maintenance Replacing plates and gaskets is easy; replacing heat exchange tubes is difficult Changing the heat exchange area Not possible by adding or removing plates Changing the process configuration Possible; however, it is not possible to change the number of stages

Refer to the following differences between heat exchangers: Comparison of plate heat exchangers and shell-and-tube heat exchangers. Plate Heat Exchanger Shell-and-Tube Heat Exchanger Temperature cross-over① Yes No Terminal temperature difference②°C 1 5 Operation with multiple media Yes No Pipeline connections Can be concentrated in one direction Must be arranged in several directions Overall heat transfer coefficient ratio 3-5 1 Equipment weight ratio 1 3-10 Volume of retained liquid Small Large Footprint area 1 2-5 Leak detection Easier to detect at the leak site Internal leaks are difficult to detect Visual inspection Individual plates can be inspected one by one; it is difficult to inspect the tube bundle Time required to open minutes 15-20 60-90 Maintenance Replacing plates and gaskets is easy; replacing heat exchange tubes is difficult Changing the heat exchange area Not possible by adding or removing plates Changing the process configuration Possible; however, it is not possible to change the number of stages

Hello, thank you very much for your reply. Based on your data, it is clear that plate heat exchangers have significant advantages over tubular heat exchangers. Why are the vast majority of manufacturers producing evaporators in the market today those that make tubular ones? Why is it that the vast majority of end-users also prefer to purchase tubular evaporators?

1. Plate heat exchangers have a high heat transfer coefficient. Due to the inverted arrangement of the corrugated plates, a network of contact points is formed within the fluid channels, with the flow paths changing frequently and the direction of the fluid varying as well. According to relevant data, turbulence occurs at a critical Reynolds number of around 200, which increases the film conductance coefficient and thereby enhances heat transfer. At the same time, since many support points are formed when the plates of a plate heat exchanger are assembled, this reduces the deformation of the plates under pressure; as a result, thinner plates can be used, with typical plate thicknesses ranging from 0.5 to 0.8 mm, which lowers the thermal resistance. Due to the intense turbulence of the fluid in the channels between the plates, solid particles can be suspended, the surface remains smooth, and dirt does not accumulate easily, thereby increasing the overall heat transfer coefficient. 2. Plate heat exchangers have a small volume and low floor space requirement, resulting in minimal heat loss. Plate heat exchangers have a compact structure and small size, with a heat transfer area of around 100 m2 per cubic meter. Its floor area is only 1/5 to 1/10 that of a shell and tube heat exchanger. For detachable shell and tube floating-head heat exchangers, in addition to their own space requirements, additional area is needed for core pulling inspections, resulting in high space demands; whereas plate heat exchangers only require the installation area for maintenance. Secondly, due to its small size, it dissipates less heat into the surrounding environment; with the same heat exchange area, the heat loss of a plate heat exchanger is only 1/5 that of a shell and tube heat exchanger. 3. The plate heat exchanger is flexible to assemble and easy to disassemble and clean. Plate heat exchangers can adjust the number of plates at any time to change the heat exchange area, thereby adapting to changes in thermal load. This is beyond the reach of shell-and-tube heat exchangers.

The choice is mainly based on the materials and operating conditions. Plate heat exchangers are limited in terms of pressure and temperature tolerance, and their processing capacity is lower than that of shell-and-tube exchangers. Additionally, when the materials suffer from severe scaling, it is more convenient to clean them every few days; shell-and-tube exchangers have their own advantages and disadvantages. Overall, plate heat exchangers have more advantages, so there is no need to consider shell-and-tube exchangers when plate heat exchangers can be used

I’ve learned it; thank you all for your guidance