Assessment of Influence of Flow Regime on Heat Transfer Capacity of A Shell and Tube Heat Exchanger Using Computational Fluid Dynamics Analysis

Abstract

Shell and tube heat exchangers (STHX) are widely adopted in industrial thermal systems due to their reliability and performance. As such thermo-mechanical design and sizing of these devices has become a continuously expanding and existing research domain. Following technological advancements, CFD is now widely adopted for flow analysis and design. An upcoming area as of recent is the integration of tools such as non-linear least squares regression and CFD to develop correlations capable of predicting thermal performance based on the input design parameters such as Re and Pr. However, limited applications exist for STHXs. This study focuses on the development of thermal correlations in the form of Nu = C.Rea.Prb for a small TEMA E-type STHX. For these devices, turbulence is identified as a key parameter which affects thermal and mechanical performance and is often introduced by using metal plates known as baffles. Single segmental baffles which are widely used in industry are integrated into the design. Hence, turbulence is varied as a function of both the mass flow rate and the central spacing among the baffles. CFD Modelling in ANSYS-Fluent is conducted in the steady state for six, eight, ten and twelve baffles. Following CFD analysis the data is fit using non-linear least squares regression in MATLAB Curve-Fitter Toolbox generating four correlations with applicable operating ranges. The results of the goodness of fit were reasonable, however, high 95 % confidence interval widths were evident for certain fitted coefficients leaving further potential for improvement. The work conducted highlights that the application of CFD combined with numerical tools such as non-linear least squares regression can act as an aid in the design and optimization of heat exchangers, increasing design potential for engineers and researchers.