A combined experimental and numerical approach for heat transfer enhancement in a minichannel using half rectified pulsating flows

Abstract

The miniaturization of electronic packages and their associated high-power density circuits requires more innovative cooling solutions. Single phase pulsating flows offer a promising solution due to their disruption of the thermal boundary layer. This study aims to bridge the knowledge gap by using experimental and computational methods to investigate the complex flow characteristics of laminar pulsating flows in a heated rectangular minichannel and couple that analysis with an investigation of thermal-hydraulic performance. Experimental analysis involves a uniformly heated thin foil approximating a constant heat flux bottom wall. Wall temperature measurements are recorded using an infrared thermography system. Analogous to the experimental conditions, a three-dimensional conjugate heat transfer computational model is developed with a volumetric heat generation source. Positive and negative half rectified sinusoidal pulsating flow waveforms are studied for dimensionless pulsation frequencies or Womersley numbers of 𝑊𝑜 = 2.5 and 5.1 at a fixed flow rate amplitude 𝐴0 = 3. For the positive half rectified waveform, a marginal enhancement in heat transfer of 2.2% for 𝑊𝑜 = 2.5, 𝐴0 = 3 was obtained. Whereas the negative half rectified case leads to a heat transfer enhancement of 9% and 6% for 𝑊𝑜 = 2.5 and 𝑊𝑜 = 5.1 respectively, with a high thermal performance of 𝜂 = 2.4 over corresponding steady flow.