Empirical values of the overall heat transfer coefficient K in some shell-and-tube heat exchangers
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Cold fluid, Hot fluid, Total heat transfer coefficient K, W/(m2·℃): Water, Water: 850–1700; Water, Gas: 17–280; Water, Organic solvents: 280–850; Water, Light oil: 340–910; Water, Heavy oil: 60–280; Organic solvents, Organic solvents: 115–340; Water, Water vapor condensation: 1420–4250; Gas, Water vapor condensation: 30–300; Water, Low-boiling-point hydrocarbons condensation: 455–1140; Water boiling, Water vapor condensation: 2000–4250; Light oil boiling, Water vapor condensation: 455–1020. As for heat exchange between water and gas, as mentioned in the second row, many people think that a more precise value can be determined; some suggest 100–150. Differences exist depending on the medium used, but the values should still fall within the ranges mentioned above. If anyone needs this information, they can search online. I’ve seen many people say that this information can be found in the first volume of “Principles of Chemical Engineering,” but there are many different versions of this book, and some do not contain this information, so I’m sharing it here with everyone
1? Estimate the heat transfer area and initially select the heat exchanger model. (1) Calculate the heat transfer rate based on the heat transfer requirements. ? (2) Determine the temperatures of the fluid at both ends of the heat exchanger, calculate the qualitative temperature, and determine the fluid properties. ? (3) Calculate the heat transfer temperature difference, and determine the number of shell passes based on the principle that the temperature difference correction factor Δt should be ≥ 0.8. ? (4) Select the two-fluid flow channel, and choose the type of heat exchanger based on the temperature difference between the two fluids. ? (5) Initially select the overall heat transfer coefficient K value based on the empirical range of overall heat transfer coefficients. ? (6) Calculate the heat transfer area using the overall heat transfer rate equation, and determine the specific model of the heat exchanger based on S (if it is for design purposes, the basic dimensions of the heat exchanger must be determined). 2? Calculate the pressure drops in the tube side and shell side: For the selected type of heat exchanger, calculate the pressure drops in each of these sides to determine whether they meet the required specifications. If the requirements are not met, adjust the number of tubes or the spacing between baffle plates, or select other types of heat exchangers, and calculate the pressure drop until the requirements are satisfied. 3? Calculate the overall heat transfer coefficient and the heat transfer area: Using the correlations for convective heat transfer coefficients, determine the convective heat transfer coefficients inside and outside the tube, select the fouling thermal resistance, and then compute the value of the overall heat transfer coefficient. Based on this calculation, the actual heat transfer area is verified using the K value; if the heat transfer area provided by the heat exchanger is 10–20% larger than the required area, then the selected heat exchanger is appropriate. Otherwise, a different value for K must be selected, and the above steps must be repeated until the requirement is met.
It has some reference value, but specific situations need to be considered on a case-by-case basis
It’s useful; thanks to the original poster for the summary
It has some reference value, but in reality it’s difficult to determine certain things; the range of organic solvents is too wide. Should the same value be used for all organic solvents?
It has some reference value; thanks to the original poster. Each case needs to be analyzed on its own – in reality, it’s difficult to determine certain things, as the range of organic solvents is too wide.
The values seem quite different from those in the \"Plate Heat Exchanger Engineering Design Manual\" compiled by Yang Chonglin. According to his data, for water-to-water heat exchange, the range is 2800–4650; for water vapor (or hot water) to oil, it’s 870–930; for cold water to oil, it’s 400–350; and for gas to water, it’s 28–58. The differences are significant, and even when making estimates, the errors are considerable
Cold fluid, Hot fluid, Overall heat transfer coefficient K, W/(m2·℃): Water, Water: 850–1700; Water, Gas: 17–280; Water, Organic solvents: 280–850; Water, Light oil: 340–910; Water, Heavy oil: 60–280. Organic solvents, Organic solvents: 115–340. Water, Water vapor condensation: 1420–4250. Gas, Water vapor condensation: 30–300. Water, Low-boiling-point hydrocarbons condensation: 455–1140. Water boiling, Water vapor condensation: 2000–4250. Light oil boiling, Water vapor condensation: 455–1020. The range of overall heat transfer coefficients provided by the original poster seems to include the effect of fouling resistance, right?