How should the plate heat exchanger gaskets and heat transfer coefficient be selected?
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Dear experts, our project is in the process of selecting a plate heat exchanger. There are mainly two types: one uses hot water at 160°C to heat the desalinated water, while the other uses circulating water at 31°C to cool the desalinated water. If I choose EPDM gaskets for these two types of plate exchangers, how would that be? Are there any better options for gaskets? Please explain in detail. Additionally, regarding the heat transfer coefficient, some suggest 4000 W/(m2·℃) while others recommend 6000 W/(m2·℃). How can we determine which value is more reasonable for the heat transfer coefficient? Please explain in detail. Thank you very much!
Use software to calculate K, htri/EDR; the gasket material can be found according to the standards for replaceable plates
The heat transfer coefficient is not a fixed value; it must be calculated based on the actual operating conditions. Add me on WeChat if it’s convenient – 1505070709 – Qin
For water, ordinary EPDM and NBR are both suitable. Corrosion resistance is no problem; rubber is mainly vulnerable to organic solvents. The second factor is temperature; normally, EPDM can withstand temperatures of 140 degrees. If the temperature is high, the lifespan of the gasket will be reduced, but high-temperature EPDM should still be suitable. Fluororubber can withstand temperatures of 180 degrees, but it is too expensive, making it uneconomical. If it’s worthwhile, you can provide the inlet and outlet temperature parameters to the heat exchanger manufacturer, and they will help you do the calculations. If you want to calculate it by yourself, HTRI will do. 6000 is a bit high; it’s related to temperature, and the range of K values is quite wide. If you have to estimate, it’s better to be conservative and go with around 3,000.
For operating temperatures below 150°C, EPDM is used; for higher temperatures, fluororubber should be employed. The heat transfer coefficient also depends on the flow rate between the plates. In China, a value of 3000–4000 is generally adopted; you can just ask a manufacturer to choose one for you
The temperature resistance of EPDM is generally around 150 degrees; HEPDM can be considered for temperatures up to 160 degrees. The heat transfer coefficient depends on the water quality; if the water quality is good, a heat exchanger with a smaller plate spacing can be chosen, resulting in a higher heat transfer coefficient. Based on the operating conditions provided by the poster, the heat transfer temperature difference is relatively large, so the heat transfer coefficient will be somewhat low; a value around 4000–4500 should be reasonable. 6000 should be too high; only small-temperature-difference heat exchangers can achieve it
I am a manufacturer of heat exchangers, and I’ll answer your question: EPDM gaskets will work fine for this purpose. Regarding the heat transfer coefficient, it needs to be calculated based on the temperature differences and flow rates under different operating conditions, rather than being a fixed value.