Posted by Kashyap Vyas on September 12th, 2016
Design development of shell and tube heat exchangers require engineers and manufacturers to follow industry standards laid by regulatory international and national bodies. The process of shell and tube heat exchanger design is performed considering the thermal and mechanical aspects, to ensure that it operates efficiently and safely. Let’s look at both the aspects in detail.
Designing the shell and tube heat exchanger for thermal parameters requires multiple iterations and is normally performed using the proprietary software available within the company or other programs developed by regulatory bodies. The importance however in the thermal design process is to ensure that the engineer is able to acknowledge the design logic employed behind the calculations.
Determining thermal parameters like heat transfer coefficients and pressure drop in the heat exchanger requires first deciding the sides where the hot and cold fluids are allocated, the header types used for front and rear of the exchanger, shell type to be used, baffle types as well as the diameter of tube and its layout. Moreover, design elements like tube length, diameter of the shell, pitch of the baffle and number of passes are also required to be selected. These design parameters are then iterated multiple times to achieve a final design that provides maximum overall heat transfer within allowable pressure drops.
Shell and tube heat exchanger must also possess required mechanical strength to withstand pressure and temperature safely. As such, the mechanical design involves specifying shell thickness, flange thickness, etc. The design procedure is usually carried out according to the standard pressure vessel design code like ASME Boiler and Pressure Vessel Code (BPVC) or the British Master Pressure Vessel Standard, BS 5500. However, manufacturers across the globe usually prefer ASME BPVC for their heat exchanger design.
This code is described in 11 sections, but the Section VII (Confined Pressure Vessels) is highly relevant in the design of heat exchangers. Also, the Section-II for Materials and Section V – for Non Destructive Testing is extremely helpful for engineers and designers in developing efficient heat exchanger for diverse set of applications. ASME BPVC has also a provision to perform virtual tests using finite element analysis for heat exchanger design.
In several countries however, there are separate national codes which are required to be adhered to while designing heat exchangers, apart from ASME and BS. To reduce the complexities in code adherence, the International Standards Organization has begun developing a common, globally recognized code. However, its adoption might still take some time.
Hi-Tech provides a comprehensive design support to manufacturers of industrial heat exchangers with a team of mechanical design engineers, FEA specialists and domain experts. Adhering to international standards like ASME, BS and NBIC, we have helped clients in achieving certifications like “U” stamp and “R” stamp, by delivering services like 3D CAD modeling, manufacturing drawings development, FEA and CFD analysis.
About Author: Kashyap Vyas is an Engineer at Hi-Tech and holds a Master’s degree in Thermal Engineering with several research papers to his credit. He covers CAD and CAE topics for the engineering industry. His contributions are primarily focused on encouraging manufacturers and suppliers to adopt virtual product development tools to build efficient products with reduced time-to-market.