Simulation modeling of convection processes in heat exchangers

The article describes the method for calculating the influence of convection on heat exchange in heat exchangers (HE) with spirally wound tubes and also presents a model that implements this object ignoring heat losses to the atmosphere. Information about the calculation code, its thermal-hydraulic blocks is given, and the necessary equations are proposed to identify the influence of free and forced convection on heat transfer in SimInTech dynamic modeling environment. Prior to the study, the calculation model was verified, where the relative error was 1.3 %, which is acceptable for this model. After successful verification, calculations were performed for the heat exchanger within the design limits and beyond its boundaries. Following on from the findings, it can be concluded that the speed of the medium at which free convection does not affect the efficiency of the heat exchanger, where 324 tubes is 1.08 m/s; for TO with 93 tubes is 1.25 m/s. Subsequently, a recommendation was developed for the use of shell-and-tube heat exchangers with spiral wound tubes: in order to guarantee effective heat transfer and minimize the impact of free and forced convection, designers should strive to maintain an average flow velocity in the heat exchanger tubes of at least 1.0 m/s; if it is impossible to maintain the speed, then it is necessary to take into account the influence and correctly position the heat exchanger so that the directions of forced and free convection coincide.

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