Numerical Investigation of the Effect of Variable Baffle Spacing on the Thermal Performance of a Shell and Tube Heat Exchanger

Halil Bayram,Gökhan Sevilgen

doi:10.3390/en10081156

Abstract

In this present study, numerical and theoretical analysis were both used to investigate the effect of the variable baffle spacing on the thermal characteristics of a small shell and tube heat exchanger. The numerical study was performed by using a three dimensional computational fluid dynamics (CFD) method and the computations were performed under steady-state conditions. We employed five different cases where the first had equal baffle spacing and the others had variable ones considering different configurations for balancing the pressure drop on the shell side. Theoretical calculations were run using the Bell-Delaware and Kern methods which are the most commonly used methods in the available literature. We show that the thermal performance of a shell and tube heat exchanger can be improved by evaluating together the results of the CFD and Bell-Delaware methods. From the numerical results, we can say that variable spacing with centered baffle spacing scheme can be proposed as an alternative shell side construction layout compared to an equal baffle spacing scheme. The numerical results were in good agreement with the theoretical data in the available literature.

Highlights

Heat exchangers are devices made for efficient heat transfer from one zone to another in order to transfer energy and they are widely used in different industries like the automotive, heating, ventilation and air conditioning (HVAC), chemical and food industry and so on [1,2]
Certain standards and correlations proposed by the Tubular Exchanger Manufacturers Association (TEMA) have to be considered when a well-designed shell and tube heat exchanger is desired for industrial applications
The 3D model of the heat exchanger was obtained considering inlet and outlet plenums, whereas in the literature, some numerical investigations were performed by applying a constant mass flow rate for each tube individually and constant temperature boundary conditions were applied to the tube surfaces in general, but in this study, we considered the effect of the velocity distribution of the inlet and outlet regions on the flow inside the tubes and the shell and tube side flows were both solved simultaneously with energy equations

Summary

Introduction

Heat exchangers are devices made for efficient heat transfer from one zone to another in order to transfer energy and they are widely used in different industries like the automotive, heating, ventilation and air conditioning (HVAC), chemical and food industry and so on [1,2]. In a baffled shell and tube heat exchanger, the baffles are used for different reasons such as providing support for tubes, obtaining a desirable fluid velocity to be maintained for the shell-side fluid flow, and preventing the tubes from vibrating. They direct the shell side flow to enhance the heat transfer coefficient but their usage produces an increased pressure drop [6]. There are numerous studies on the impact of the baffle cut, number of baffles, baffle type, etc. on the thermal performance of the shell and tube heat exchanger in the available literature, Energies 2017, 10, 1156; doi:10.3390/en10081156 www.mdpi.com/journal/energies

Methods

Results

Discussion

Conclusion