Transient Thermal Analysis Of Finned Cross -Flow Heat Exchangers By Simulation

Abstract

Cross-flow finned heat exchangers are used in various oil and gas industries. Finned heat exchangers are used in cases where the volume and weight of the exchanger are required to be low and the efficiency of the exchanger is high. These types of exchangers have fins or attachments on the main surface that are used to increase the heat transfer surface. Since the heat transfer coefficient on the gas side is much smaller than that of the liquid, finned heat transfer surfaces on the gas side are used to increase the heat transfer surface. Fins are widely used in gas-gas or gas-liquid heat exchangers where the heat transfer coefficient on one or both sides is small and a compact heat exchanger is required. This paper describes the importance of thermal process control, analyzes its performance problems, and presents a mathematical model of heat transfer processes in a heat exchanger. Three-dimensional simulations with sub-millimeter accuracy were performed with adaptive meshing, which was verified with GCI, and the Navier-Stokes RANS equations were solved with the k-omega SST turbulence model. The simulated boundary conditions included air flow velocities ranging from 2 to 5 m/s and a constant heating rate of 1.5 kW/m2 to the tube walls. The results showed that the heat transfer at the tips of the fins was up to 30% higher than in the middle regions due to the formation of turbulent vortices, and the Nusselt number for such a phenomenon was calculated to be 62.5. Finally, considering that the weight and volume of these fins are of particular importance due to their application, the effect of the materials and geometry of the heat exchanger profile on heat transfer were investigated.