Numerical Studies of Flow and Temperature Distribution in a Micro-heat Exchanger
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RESEARCH ARTICLE-CHEMICAL ENGINEERING
Numerical Studies of Flow and Temperature Distribution in a Micro‑heat Exchanger E. Omidbakhsh Amiri1 · M. Ghasemi Ahmad chali1 Received: 24 March 2020 / Accepted: 12 July 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract In the design of micro-heat exchangers, the flow and temperature uniformities are essential parameters for achieving better performance. In this work, uniformity of flow and temperature distributions was numerically studied in parallel micro-channels. Carboxymethyl cellulose (CMC) aqueous solution (0.5 wt.%) was used as a cooling (working) fluid. The rheological behavior of this solution is as power-law non-Newtonian fluid. Different manifold structures were used, and the effect of them on the flow and temperature distributions was studied. Results found that rectangular structure has lower values for temperature difference and uniformity parameter than other cases. So, with the rectangular structure of manifold, temperature and flow distributions are more uniform. In the next consideration, the direction of the inlet flow to micro-channels was studied. Three directions (vertical (90°), horizontal (0°) and oblique (45°)) were used. With different directions, various velocity profiles in the micro-channels were shown. As, with horizontal inlet flow, velocity in middle micro-channel is higher than other micro-channels, while, with vertical inlet flow, the first micro-channel has maximum velocity and velocity decreases in next micro-channels. Also, between these three directions, horizontal inlet flow has better uniformity of flow and temperature. Keywords Manifold · Micro-channel · Non-Newtonian fluid · Numerical simulation
1 Introduction Microfabrication technologies are used in many industrial and engineering systems. The properties of micro-devices offer essential advantages, such as high mass and heat transfer rates. So, they offer the possibility to realize a high throughput within a small volume [1]. Studies on the flow distribution in micro-channels devices can help to improve their performance. In heat exchangers, different methods were used to improve thermal performance. In some of them, nanofluid with their excellent thermal properties was used as working fluid [2–4], and in some other studies, the proper structure of heat exchanger was considered [5]. In many micro-reactors and micro-heat exchangers (such as electronic devices), for better performance, more temperature uniformity is a requirement [6]. Local high temperature and thermal stress * E. Omidbakhsh Amiri [email protected] 1
Department of Chemical Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran
may result in the deformation of the electronic circuit and deteriorate the efficiency of the electronic circuit [7]. Three useful and demanded parameters on the thermal design of the electronic devices are the high heat flux, small temperature non-uniformity and low pumping power. So, the temperature distribution must be studi
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