Investigating Tubes Material Selection on Thermal Stress in Shell Side Inlet Zone of a Vertical Shell and Tube Heat Exchanger

Abstract

In this study, the effect of the tube material on the thermal stress generated in a vertical shell and tube heat exchanger is investigated. Shell and tube heat exchangers are the most common heat exchangers used in industries. One of the most common failures in these exchangers in the industry is the tube failure at the junction of the tube to tubesheet. When the shell side and the tube side fluid with temperature difference, flow in the heat exchangers, a temperature gradient occurs in the tube. Temperature gradients cause thermal stress in the tube, especially at the junction of the tube to tubesheet where there is no possibility of expansion and contraction. Therefore, in this study, it was tried to make changes in order to reduce the effect of thermal stress in the failure. For this purpose, temperature distribution, thermal stress distribution, and its effects on failure were investigated by changing the material. In order to perform the required analysis, three dimensional models of the inlet zone of the shell side were created, and steady state temperature distribution was obtained, and the stress caused by temperature gradient was analyzed. Because of the interference between fluid and structure in this study, the indirectly coupled field analysis was used. In this way, the thermal analysis results were converted into indirect couple structural analysis as loading. Among the analyzed materials, the lowest rate of stress is for the copper tubes. However, steel tubes have the best safety factor regarding thermal stress.

Keywords

• shell and tube heat exchanger
• tube material
• temperature gradient
• thermal stress