PERFORMANCE PREDICTION AND COMPARATIVE ANALYSIS FOR A DESIGNED, DEVELOPED, AND MODELED COUNTERFLOW HEAT EXCHANGER USING COMPUTATIONAL FLUID DYNAMICS

This paper presents a systematic approach for three-dimensional analysis of a counterflow heat exchanger, where hot water flows through a 12.7-mm-diameter tube and cold water flows through a 20-mm-diameter tube concurrently along the length of the heat exchanger. In particular, the flow and the temperature fields are resolved by using commercial computational fluid dynamics (CFD) software. The analysis and developments are made by working over a circular tube bank using different numerical methods and CFD simulations while considering turbulent models. Significant geometric optimization is made in the heat exchange between the circular tubes by limiting the cost since no polymers or additives are used and steering clear of flow separation, which has a greater impact on the flow phenomena. In order to analyze heat transfer characteristics, we carried out numerical analyses by altering the hot and cold fluid inlet temperatures. To simulate the flow, the renormalization group k-ε turbulence model was chosen. The simulated outcomes of the counterflow heat exchanger are compared with the existing literature to find the logarithmic mean temperature difference (LMTD). The following two factors were considered: (1) the effect of changing the temperature at one end and fixing it at the other end on the heat transfer and LMTD and (2) the effect of altering the mass flow rates at every step by fixing the temperature. There was a significant amount of change in the LMTD while increasing the hot fluid temperature (with an average of 31.41) rather than increasing the cold fluid temperature. However, by further decreasing the cold fluid inlet temperature the LMTD peaks at a value of 27.32. It was also observed that changing the cold fluid flow rate gives better insight into the heat transfer and LMTD with average of 28.94 and an average error of 8.455%, respectively.