Experimental and numerical studies on heat transfer enhancement of microchannel heat exchanger embedded with different shape micropillars

• Published in: Applied thermal engineering 2020-07, Vol.175, p.115296, Article 115296
• Main Authors: Zhou, Fang, Zhou, Wei, Zhang, Chenying, Qiu, Qingfu, Yuan, Ding, Chu, Xuyang
• Format: Article
• Language: English
• Subjects: Computer simulation; Fluid flow; Fluid flow characteristic; Heat exchangers; Heat transfer; Heat transfer enhancement; Laser micromilling; Mathematical models; Microchannel heat exchanger; Microchannels; Micropillars; Numerical analysis; Pressure loss; Reynolds number; Velocity; Vorticity
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2020.115296

•Heat transfer enhancement performance of microchannel embedded with micropillars are studied.•Temperature and velocity distribution through numerical simulation are obtained.•Larger Nusselt number is obtained for microchannel with different micropillars.•Better thermal performance was found for regular and irregular drop-shaped micropillars. The experimental and numerical investigations on heat transfer enhancement by different shapes of micropillars embedded in microchannel heat exchanger were performed. The temperature, velocity and vorticity contour distribution were obtained through numerical simulation. A series of experiments were conducted to validate the simulation model. The simulation results agreed well with the experimental results. Later, Nusselt number (Nu), pressure loss, and the overall thermal performance parameter (TP) at a range of Reynolds numbers (Re) were presented and compared. The experimental results showed that the Nu/Nu0 ratios for the tested microchannels fell in the ranges of 1.65–1.9 for micropillars of square (type A), circle (type B), fan-shaped (type C), and 1.6–1.7 for micropillars of drop-shaped (type D) and irregular drop-shaped (type E). However, the microchannels with micropillars of type D and E show an increase of about 20–40% in the pressure loss, while the microchannels with micropillars of type A, B and C showed an increase of above 60%. Furthermore, much higher TP values were observed for type D and E micropillars, indicating better heat transfer performance of microchannel heat exchanger in the tested range of Reynolds number.