Thermal Stress and Deformation of Hollow Paddle-Shaft Components with Internal High Temperature Molten Salt Flow

Taha Rajeh,Houlei Zhang,Basher Hassan Al-Kbodi

doi:10.3390/pr8121557

Taha Rajeh, Houlei Zhang + Show 1 more

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https://doi.org/10.3390/pr8121557

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Abstract

Excessive thermal stress and deformation are important reasons causing disservice of high temperature heat exchangers. This paper presents thermal stress and expansion analysis of single-leaf type hollow paddle-shaft components with internal high temperature molten salt flow based on three-dimensional numerical simulations. The results show that the hollow paddles enhance the heat transfer and decrease the maximum thermal stress simultaneously with the expense of a much higher pressure drop than that of solid paddles. The cumulative von Mises stress distribution curve shows that the stress distribution of the component with hollow paddles is more uniform than that with solid paddles. The radial and axial deformations do not differ much for the components with hollow and solid paddles. A larger volume of the fluid space in the hollow paddles leads to stronger heat transfer, smaller maximum thermal stress, and more uniform stress distribution. The effects of the paddle height, the diameter and number of flow holes, the molten salt flow rate, and the material-side heat transfer coefficient are identified. The advantages of hollow paddle designs in both heat transfer and thermal stress (local and overall) performance are revealed. The work in this study can provide a reference for the design and optimization of hollow paddle heat exchangers with high temperature molten salt as working fluid.

Highlights

High temperature heat exchangers (HTHEs) are widely used in many areas, including traditional industrial sectors and recently developed renewable energy fields [1,2,3,4,5].The structures of HTHEs involve conventional shell-and-tube, fin-and-tube, and many new designs.Besides the thermo-hydraulic performance, thermal stress and deformation are critical in the design of HTHEs
One important progress in thermal stress and deformation evaluation in recent years is the broad application of the finite element method (FEM) for solid mechanics combined with computational fluid dynamics (CFD) simulation of flow and heat transfer [6,7]
The results show that the significant parameters that affect the temperature and stress distributions are the fin diameter and non-uniform heat transfer coefficient

Summary

Introduction

High temperature heat exchangers (HTHEs) are widely used in many areas, including traditional industrial sectors and recently developed renewable energy fields (solar energy, biomass energy, etc.) [1,2,3,4,5]. Besides the thermo-hydraulic performance, thermal stress and deformation are critical in the design of HTHEs. Excessive thermal stress and thermal expansion may cause disservices of HTHEs. As a traditional topic, thermal stress and deformation have been studied by many researchers for different heat exchanger structures. One important progress in thermal stress and deformation evaluation in recent years is the broad application of the finite element method (FEM) for solid mechanics combined with computational fluid dynamics (CFD) simulation of flow and heat transfer [6,7]

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