Immersion water heaters are used worldwide to heat water for domestic as well as industrial usage. They usually consist of a cylindrical pipe or tube immersed into a bucket or a tub filled with the fluid requiring heating. This tube encases an electric resistance heating element. When an electric current is passed through this resistance, it acts as a heat source. Heat is transferred from this cylindrical heating element to the surrounding fluid. As the temperature of the fluid near the cylindrical element increases, its density decreases compared to the fluid farther away from the heating element. This density gradient is responsible for moving the hotter fluid to the top and the cooler fluid to the bottom, establishing natural convection as the primary mode of heat transfer in this fluid.
In this homework, we will learn how to set up a simulation to estimate the overall heat transfer due to natural convection over a horizontal cylinder using Ansys Fluent. In addition, we will examine the distribution of the Nusselt number along the cylinder wall. Finally, we will compare the obtained solution with two correlations from the literature.
Download the Mesh file required for setting up the simulation and associated Case & Data files here. Follow the instructions below to set up this simulation in Ansys Fluent starting with the Mesh file. In case you face any issues setting up or running the simulation, refer to the corresponding initial and final Case and Data files.
Let’s now analyze the simulation and understand the heat transfer due to natural convection over a heated horizontal cylinder.