Numerical study of a jet impacting a heated object

Abstract: Heat transfer brought about by impinging jets is common in several industrialapplications such as the cooling of heated objects. The purpose of this investigationis to create a numerical model of an impacting jet, then to use it in parametricresearch and in the cooling of an electronic device. In this work, COMSOL Multiphysics software has been used to carry out a numericalanalysis of a cooling jet impacting a vertical surface. Water and air are the two fluidscompared to each other, and three different materials were selected for modelling theheated object. The model created can be used in many areas. For example, the caseof the air jet hitting an aluminum object is commonly used in the cooling of electronicdevices while the water jet hitting a brick is used in building and construction. Inother words, the highlight of this project is to create a useful tool that can be easilymodified in order to investigate a specific area. To set an example, the cooling of aninsulated gate bipolar transistor (IGBT) has been investigated in this work. Equations related to the conservation of mass and momentum, coupled to the energyconservation equation, have been solved. Several assumptions were carefully andreasonably considered to simplify the simulation and ensure the accuracy andreliability of the results. The effect of the type of the heated material and the distancebetween the tube nozzle and the heated object have been investigated in the study.The results show that the jet is effective in cooling heated objects and can be used inparametric research. In fact, surface temperature and jet velocity have been displayedand discussed and it has been found that the most optimal combination for efficientheat transfer is a shorter distance between the tube nozzle and the heated object, amaterial with higher thermal conductivity, and water as the jet fluid. The impingingjet device has been tested in the cooling of Insulated Gate Bipolar Transistor (IGBT)and the results showed that the temperature of the IGBT drops by 14.57%. Despite the accuracy of the results, it is important to recognize the limits of thenumerical model such as the discretization of the physical domain, the resolution ofthe mesh, the assumptions, and the simplifications. In addition, this investigation waslimited to three variable factors. Therefore, further studies are recommended tofurther optimize the cooling effect of the jet, such as the study of nozzle shape, jetvelocity, jet mass flow rate and a 3D-simulation.