Effects of manifold design parameters on flow uniformity in parallel mini-channels

Abstract

Flow maldistribution in parallel mini-channels is a critical obstacle to the efficient design of mini-channel heat sinks. The flow maldistribution is known to cause dryout incipience in some channels, which triggers critical heat flux, eventually leading to physical burnout and catastrophic device failure. Hence, enhancing flow uniformity by reducing flow maldistribution is critical. While several attempts have been made to reduce flow maldistribution, most have focused on providing strategic frameworks for enhancing flow uniformity in channels. The present study develops a new predictive tool for quantitatively assessing flow maldistribution in parallel channels based on the parametric effect. Five parameters are considered: channel height, channel width, header length, connection tube diameter, and total volumetric flow rate. Thirty-six different heat sinks are numerically investigated to study the influence of each parameter on flow uniformity in channels. A decrease in channel height, channel width, and total volumetric flow rate and an increase in header length and connection tube diameter reduces the maldistribution factor enhancing channel flow uniformity. By analyzing the effects of these parameters on the flow uniformity in channels, a new correlation for the maldistribution factor constructed with dimensionless groups, including the design parameters, is proposed, which fits the numerical predictions for the maldistribution factor with excellent accuracy, evidenced by a root-mean-squared-error of 1.0%. The parametric assessment of the effects of the different parameters on the flow maldistribution using the new correlation shows that the magnitude of the relative influence of each variable on flow maldistribution can be expressed in the following order: header length > channel height > connection tube diameter > total volumetric flow rate > channel width.