Selection of heat exchangers

Selection of heat exchangers: 1. They must meet the requirements of the process conditions. The material and structural type of the heat exchanger are determined by taking into account various process factors such as pressure, temperature, physicochemical properties, and corrosivity. 2. High heat transfer efficiency: To improve heat transfer efficiency, heat exchangers must increase the heat transfer coefficient of the fluid and reduce thermal resistance. This issue must be fully considered when determining the structural type of the heat exchanger. If the heat transfer coefficients of the two fluids involved are similar and the temperature difference is not large, a shell-and-tube heat exchanger can be chosen ； If the temperature difference is large, a shell-and-tube heat exchanger equipped with expansion joints should be selected ； If the temperature difference is large, a floating-head heat exchanger should be chosen ； If the heat transfer coefficients of the two fluids differ significantly, and one of the fluids is a gas, a finned tube heat exchanger should be selected ； If both fluids are gases and their heat transfer coefficients are low, a plate-fin heat exchanger should be chosen. 3. The fluid resistance loss should be low. The level of fluid resistance loss in a heat exchanger is directly related to the amount of energy consumed. Although increasing the flow velocity can improve the heat transfer coefficient, the high energy consumption required by the pumps or fans used to move the fluid makes it uneconomical. Therefore, the flow velocity of the fluid should be appropriate; relevant design manuals can be consulted to determine a reasonable flow velocity.

Excuse me, is the expansion joint of the shell-and-tube heat exchanger on the 2nd floor with an expansion joint located on the shell side? What does the specific heat transfer coefficient generally refer to, and what is the structure of a plate-fin heat exchanger?

1. Select the heat exchanger structure based on the medium used in the heat exchanger； Plate heat exchangers can be used only in closed-loop systems ； Floating coil heat exchangers are suitable for applications with poor water quality. 2. Plate heat exchangers are a better choice for situations where it is necessary to increase the heat exchange capacity later on ； 3. Select the heat exchanger area ； 4. Selection and design calculation steps for heat exchangers ； Estimate the heat transfer area and preliminarily select the heat exchanger model to determine the flow paths for the two fluids within the heat exchanger. (1) Calculate the heat transfer amount based on the heat transfer task ； (2) Determine the temperatures of the fluid at both ends of the heat exchanger, calculate the qualitative temperature, and determine the fluid properties ； (3) Determine the type of heat exchanger based on the temperature difference between the two fluids ； (4) Calculate the average temperature difference, and determine the number of shell passes or adjust the final temperature of the heating or cooling medium in accordance with the principle that the temperature difference correction factor should be at least 0.8 ； (5) Select the overall heat transfer coefficient based on the empirical range of overall heat transfer coefficients or the actual production conditions ； (6) Estimate the heat transfer area using the overall heat transfer rate equation, and determine the basic dimensions of the heat exchanger or select the equipment specifications according to series standards. 5. Calculate the tube side and shell side resistance. When calculating the overall heat transfer coefficient and the heat transfer area, the actual heat transfer area of the heat exchanger used should be about 10%–25% larger than the area required for the calculations.

The expansion joint is located on the shell side of the heat exchanger and is used in tube-and-shell heat exchangers. It is used to relieve the pulling stress caused by the temperature difference between hot and cold fluids; the heat transfer coefficient is essentially the coefficient of heat transfer, right? It is obtained through computational calculations and represents a parameter indicating the efficiency of the heat exchanger. It seems that the original poster knows very little about heat exchangers; it is recommended that you first study *GB151 and the heat exchanger design manuals. Electronic versions of these materials are available on the forum. This post was last edited by wode*aohei on 2009-2-18 at 17:04.]

Personal opinion: I think the issues to consider are 1) the production process, 2) the properties of the fluid (corrosivity, thermal conductivity, viscosity, tendency to form scale), and 3) pressure and temperature. 4. Requirements for cleaning and maintenance. 5. The price of the material, its service life, and ease of manufacturing, etc.