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The Difference Between Plate Heat Exchangers and Shell-and-Tube Heat Exchangers
Release time:
2024-03-27
Plate heat exchangers feature high heat transfer coefficients, a small footprint, minimal heat loss, and low investment costs.
1. Plate heat exchangers have a higher heat transfer coefficient than shell-and-tube heat exchangers.
Because the corrugated plates are arranged in an inverted manner relative to one another, forming complex flow channels, the fluid undergoes rotational, three-dimensional flow within these channels. This allows turbulent flow to occur even at relatively low Reynolds numbers (typically Re = 50–200), resulting in a high heat transfer coefficient—generally considered to be 3–5 times that of shell-and-tube heat exchangers.
2. Large logarithmic mean temperature difference, small terminal temperature difference
In shell-and-tube heat exchangers, the two fluids flow separately through the tube side and the shell side, resulting in predominantly crossflow. This leads to a small logarithmic mean temperature difference correction factor. In contrast, plate heat exchangers typically operate with parallel or counterflow, and their correction factors usually hover around 0.95. Moreover, the cold and hot fluids in plate heat exchangers flow parallel to the heat transfer surface without any bypass flow, which minimizes the terminal temperature difference—resulting in a temperature approach of no less than 1°C for water-to-water applications, whereas shell-and-tube heat exchangers generally have a temperature approach of 5°C.
3. Small footprint
Plate heat exchangers feature a compact structure, with a heat transfer area per unit volume that is 2 to 5 times greater than that of shell-and-tube heat exchangers. Unlike shell-and-tube designs, which require dedicated space for extracting and inspecting the tube bundle, plate heat exchangers can achieve the same heat transfer capacity while occupying only about 1/5 to 1/8 the floor area of a shell-and-tube heat exchanger.
4. Easily Adjustable Heat Transfer Area or Flow Configuration: By simply increasing or decreasing the number of stack layers, you can increase or decrease the heat transfer area as needed; by altering the arrangement or quantity of plates, you can achieve the desired flow configuration and adapt to new heat transfer conditions—whereas it is virtually impossible to increase the heat transfer area of shell-and-tube heat exchangers.
5. Lightweight: The aluminum foil used in plate heat exchangers is only 0.1–0.2 mm thick, whereas the heat transfer tubes in shell-and-tube heat exchangers are 2.0–2.5 mm thick. The shell of a shell-and-tube heat exchanger is much heavier than the frame of a plate heat exchanger; in general, a plate heat exchanger weighs only about one-fifth as much as a shell-and-tube heat exchanger.
6. Low price
Using the same materials and under the same heat transfer area, plate heat exchangers are approximately 40%–60% cheaper than shell-and-tube heat exchangers.
7. Easy to make
The heat transfer plates of plate heat exchangers are manufactured using stamping, resulting in a high degree of standardization and enabling mass production. Shell-and-tube heat exchangers, on the other hand, are typically made by hand, with the shell being fully welded throughout.
8. Easy to clean
For plate heat exchangers, simply spray the cleaning agent onto the heat exchanger and use a high‑pressure water gun for cleaning—this is extremely convenient for equipment that requires frequent cleaning.
9. Low heat loss
In plate heat exchangers, only the outer plates of the heat transfer plates are exposed to the atmosphere, so heat loss can be disregarded and insulation is not required. In contrast, shell-and-tube heat exchangers experience significant heat loss and therefore require an insulating layer.
10. Low pressure loss per unit length
Due to the small gaps between heat transfer surfaces and the presence of irregularities on those surfaces, the pressure drop is lower than that of traditional smooth tubes.
11. Relatively small in size
It is 10%–20% of a shell-and-tube heat exchanger.
12. Resistant to scaling
Due to its highly turbulent internal flow, it is less prone to fouling, with a fouling coefficient that is only 1/3 to 1/10 that of shell-and-tube heat exchangers.
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