Search for: All records

Due to their lower pressure drop, impinging cold-plates are preferred over parallel flow cold-plates when there is no strict space limitation (i.e. when flow can enter perpendicular to the electronic board). Splitting the flow into two branches cuts the flow rate and path in half, which leads to lower pressure drop through the channels. A groove is used to direct the flow exiting the diffuser into the channels. The number of the geometric design parameters of the cold-plate will vary depending on the shape of the groove. In this research, the response surface method (RSM) was used to optimization the fin geometry of an impinging cold-plate with a trapezoidal cross section groove. The cold plate is used for warm water cooling of electronics. Three fin parameters (thickness, height, and gap) and three groove parameters were optimized to reach minimum values for hydraulic and thermal resistances at fixed values of coolant inlet temperature, coolant flow rate, and electronic chip power. 

Recent commercial efforts have reestablished the benefits of cooling server modules using direct liquid cooling (DLC) technology. The primary drivers behind this technology are the increase in chip densities and the absolute need to reduce the overall data center power usage. In DLC technology, a cold plate is situated on top of the chip with thermal interface material between the chip and the cold plate. The low thermal resistance path facilitates the use of warm water which helps data centers in replacing the chilled water system by a water side economizer utilizing ambient temperature. This work describes the effort to leverage DLC by employing microchannel cold plates to cool multi-chip modules. The primary objective of this work is to build a sophisticated test rig to characterize the flow and thermal performance of a microchannel cold plate for cooling a two-die chip. This study highlights the challenges of building an experimental setup which simulates a two-die chip package and the approaches taken to overcome the challenges. A parallel channel cold plate is used to benchmark the performance. Tests were conducted for a set of independent variables like flow rate, input power to dice, coolant temperature, flow direction and TIM resistance. The results are presented as PQ curves, specific thermal resistance curves and case temperature distribution reflecting the effect of changing the input variables. 

In electronics cooling, water is increasingly replacing air for applications requiring high heat flux. Water is the ideal substitute due to its high specific heat capacity and density. Indeed, high values of heat capacity (high density and specific heat capacity) enable water to receive, store and carry higher amounts of energy compared to air. Water's incompressibility and very low specific volume also requires smaller amounts of mechanical work for fluid circulation. Using warm water instead of chilled water makes the cooling process more economical, but requires more efficiently designed cold-plates. Our current work focuses on modeling and optimization of a V-groove mini-channel cold-plate using warm water as the coolant. Our results show that the performance of an impinging channel heat sink is significantly different compared to parallel channel designs. Dividing the flow into two branches cuts the fluid velocity and flow path in half for the impinging design. This reduction in the fluid velocity and flow length affects the developing thermal boundary layer and is an important consideration for a shorter length heat exchanger (where the channel length is comparable to the thermal entrance length). Distributing the coolant uniformly to every channel is a challenge for impinging cold-plates where there are strict limitations on size.