Experimental investigation of single-phase manifold microchannel heat exchanger for use in electric vehicle battery cooling/heating

• Main Author: Hwang, Terence Yong Jie
• Other Authors: Ooi Kim Tiow
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Mechanical engineering::Fluid mechanics; Science::Physics::Heat and thermodynamics
• Online Access: https://hdl.handle.net/10356/159037
• Institution: Nanyang Technological University

With the increasing development of electronic vehicles and importance of size and weight of the vehicle being directly proportional to its efficiency, there has been an incredible growth in the necessity to dissipate heat from these systems. Manifold microchannel heat exchangers have significant potential for heat dissipation, and they have garnered a considerable interest in the previous few decades since they can reduce pressure drop in the system while transfer heat more efficiently. However, the efficacy of heat transfer in a manifold microchannel with varied geometrical profiles of microchannels and manifold configurations has yet to be extensively evaluated. Consequently, the objective of this study is to determine the effectiveness of heat dissipation through manifold microchannels using microchannels and manifolds of various geometrical profiles. The experiment will focus on the three different configurations two of which are longitudinal and one of which is transverse, utilising three different geometrical profiles, namely Straight Rectangular, Re-entrant cavities, and Sinusoidal Wavy microchannels. In terms of manifold geometrical profiles, the longitudinal microchannels will use the 4- and 8-pass manifolds, while the transverse microchannels will use the 1-pass manifold. This study will further focus on the forced convection heat transfer coefficient, pressure drop across the manifold microchannel, Nusselt number in relation to the Reynold’s number and the evaluation of the performance for the different manifold microchannel geometrical profiles. The manifold microchannel heat exchangers were experimented under conditions of a range of flow rates from, 1l/min to 8l/min for all three configurations, with a maximum constant heat flux of 103kW/m^2 (10.3 W/cm^2). Results have shown that the convection heat transfer coefficient had increased up to 310% in a sinusoidal wavy, 8-pass microchannel. The transverse re-entrant microchannel also outperformed the straight rectangular microchannel by 3590%. In addition, the re-entrant microchannels have proved to obtain reduced pressure drop across the different configurations but still achieving higher heat transfer. The results of this experiment revealed excellent results of the manifold microchannels' capabilities, with considerable increase in heat transfer rate when different geometrical profiles and configurations are utilised.