Numerical analysis of turbulent flow through a shell and tube heat exchanger using kays-crawford model

Abstract

Shell and tube heat exchangers are considered as the most effective type of heat exchangers. These are used in various industrial process applications for performing tasks such as removal of process heat and feed water preheating, cooling of hydraulic and lube oil, cooling of turbine, compressor and engine, condensing process vapor or steam and evaporating process liquid or steam. In this research, a numerical analysis of turbulent flow has been carried out in a shell and tube heat exchanger using Kays-Crawford model to investigate the heat transfer performance of water and different concentrated water-MWCNT (Multi Walled Carbon Nanotube) nanofluids. A two-dimensional model of a part of shell and tube heat exchanger has been used which consists of a bundle of tubes through which the cooling fluid will flow in abundant supply entering from one side and maintaining a constant temperature. Hot fluid will enter from above the tubes and the tubes will be assumed to be made of stainless steel. The Reynold-Averaged Navier-Stokes (RANS) equations and heat transport equations with appropriate boundary conditions have been solved using finite element method. The implications of solid concentration, velocity and temperature of water- MWCNT nanofluid on the flow structure and heat transfer characteristics have been investigated in details. In addition, the present numerical result has been compared with that of Yang and Liu [44]. The numerical results indicate that the occurring solid volume fraction of nanoparticles, inflow velocity variation and inlet temperature variation characteristic significant changes in the flow and heat transfer performance. Moreover, it is noticed that using 3% concentrated water-MWCNT nanofluid, higher rate of heat transfer (12.24%) is achieved compared that of water (base fluid) and therefore to enhance the efficiency of shell and tube heat exchanger.