Experimental investigation of flow and heat transfer characteristics of pulsating flows driven by wave signals in a microchannel heat sink

• Published in: International communications in heat and mass transfer 2021-06, Vol.125, p.105343, Article 105343
• Main Authors: Xu, Chong, Xu, Shanglong, Wang, Zuyuan, Feng, Daiwei
• Format: Article
• Language: English
• Subjects: Duty cycle; Heat transfer enhancement; Nanofluid; Pulsating flow; Three-layered microchannel; Wave signals
• ISSN: 0735-1933; 1879-0178
• DOI: 10.1016/j.icheatmasstransfer.2021.105343

Applying pulsating flows and nanofluids is an effective way to enhance the heat transfer in microchannel heat sinks. Here we present a novel three-layered microchannel heat sink (TLMHS) fabricated by 3D printing and featuring a serial layer configuration. The thermal characteristics of the TLMHS under four types of pulsating flows, driven by square, triangular, sawtooth, and sinusoidal wave signal, respectively, are investigated by using a graphene-oxide-platelets (GOPs, 0.4 wt%)-water nanofluid as the coolant. The experimental results show that under the same pulsating frequency and pump power, the square wave always leads to a higher average flow rate and better heat transfer performance than the other three waves. The optimal heat transfer enhancement occurs at a frequency of 3.5–4 Hz for different duty cycle. In the low frequency range, the maximum temperature fluctuates appreciably (> 0.5 °C) around a median value. As the pump power of the pulsating flow increases from 4 to 8 W, the enhancement in the Nusselt number, with respect to a steady flow, increases from 9.8% to 16.5%. It is also affected by the duty cycle, with its variation range is 16.2% ~ 22.2% when the duty cycle is from 20% to 50%. [Display omitted] •A novel three-layered microchannel heat sink was designed and manufactured.•Pulsating flow driven by different wave signals were introduced in microchannel.•Influences of pulsating flow characteristics on heat transfer were analyzed.