Turbulent Nanofluid Flow Analysis Passing a Shell and Tube Thermal Exchanger with Kays-Crawford Model

Temperature dissipation in a proficient mode has turned into a crucial challenge in industrial sectors because of worldwide energy crisis. In heat transfer analysis, shell and tube thermal exchangers is one of the mostly used strategies to control competent heat transfer in industrial progression applications. In this research, a numerical analysis of turbulent flow has been conceded in a shell and tube thermal exchanger using Kays-Crawford model to investigate the thermal performance of pure water and different concentrated water-MWCNT nanofluid. By means of finite element method the Reynold-Averaged Navier-Stokes (RANS) and heat transport equations along with suitable edge conditions have been worked out numerically. The implications of velocity, solid concentration, and temperature of water-MWCNT nanofluid on the fluid flow formation and heat transfer scheme have been inspected thoroughly. The numerical results indicate that the variation of nanoparticles solid volume fraction, inflow fluid velocity and inlet temperature mannerism considerably revolutionize in the flow and thermal completions. It is perceived that using 3% concentrated water-MWCNT nanofluid, higher rate of heat transfer 12.24% is achieved compared that of water and therefore to enhance the efficiency of this heat exchanger. Furthermore, a new correlation has been developed among obtained values of thermal diffusion rate, Reynolds number and volume concentration of nanoparticle and found very good correlation coefficient among the values.

Thermal and Hydrodynamic Characteristics Research of a Tree-Shaped Microchannel Network Thermal Exchanger on the High-Speed Motorized Spindle

To improve the thermal dissipation of high-speed motorized spindle, core component of machine tool, according to the construction theory of mammalian circulation and respiratory system, this paper optimizes the distribution of the existing tree-shaped microchannel network structure, changes the thermal exchanger assembly mode, directly as the spindle shell, and make it possible in engineering applications. Considered the conjugate heat transfer between the spindle stator, thermal exchanger, and cooling water, a three-dimensional (3D) fluid thermodynamic model of a tree-shaped microchannel network thermal exchanger and a conventional spiral thermal exchanger are established. Both have the identical heat exchange area and inlet size. The hydrodynamic characteristics, pressure loss, temperature gradient distribution, and coefficient of performance (COP) are compared. The results indicate that the new structure proposed in this paper has more excellent hydrodynamic characteristics, smaller pressure changes, more uniform temperature gradient distribution, and greater COP. The experiment results verify the correctness of the theoretical calculation. It has a wide range of application prospects in thermal problems of high-speed spindle.