Electronics cooling

About: Electronics cooling is a research topic. Over the lifetime, 1135 publications have been published within this topic receiving 17608 citations.

Two-Phase Flow Control of Electronics Cooling With Pseudo-CPUs in Parallel Flow Circuits: Dynamic Modeling and Experimental Evaluation

Abstract: On-chip two-phase cooling of parallel pseudo-CPUs integrated into a liquid pumped cooling cycle is modeled and experimentally verified versus a prototype test loop. The system's dynamic operation is studied since the heat dissipated by microprocessors is continuously changing during their operation and critical heat flux (CHF) conditions in the microevaporator must be avoided by flow control of the pump speed during heat load disturbances. The purpose here is to cool down multiple microprocessors in parallel and their auxiliary electronics (memories, dc/dc converters, etc.) to emulate datacenter servers with multiple CPUs. The dynamic simulation code was benchmarked using the test results obtained in an experimental facility consisting of a liquid pumped cooling cycle assembled in a test loop with two parallel microevaporators, which were evaluated under steady-state and transient conditions of balanced and unbalanced heat fluxes on the two pseudochips. The errors in the model's predictions of mean chip temperature and mixed exit vapor quality at steady state remained within +/- 10%. Transient comparisons showed that the trends and the time constants were satisfactorily respected. A case study considering four microprocessors cooled in parallel flow was then simulated for different levels of heat flux in the microprocessors (40, 30, 20, and 10 W cm(-2)), which showed the robustness of the predictive-corrective solver used. For a desired mixed vapor exit quality of 30%, at an inlet pressure and subcooling of 1600 kPa and 3 K, the resulting distribution of mass flow rate in the microevaporators was, respectively, 2.6, 2.9, 4.2, and 6.4 kg h(-1) (mass fluxes of 47, 53, 76 and 116 kg m(-2) s(-1)) and yielded approximately uniform chip temperatures (maximum variation of 2.6, 2, 1.7, and 0.7 K). The vapor quality and maximum chip temperature remained below the critical limits during both transient and steady-state regimes.

Two-phase liquid cooling system for electronics, part 2: Air-cooled condenser

Abstract: An experimental study investigating the thermal performance of a two-phase thermosyphon for electronics cooling is presented in this article. Two-phase cooling implemented using a gravity-driven thermosyphon-based system represents an efficient solution for dissipating high power densities compared to traditional air-cooling approaches, allowing for increased reliability and reduced power consumption. The thermosyphon-based system consists of an evaporator with 18 individual microcooling zones connected via riser and downcomer tubes to an air-cooled condenser. Experiments were carried out with working fluid R134a for filling ratios ranging from 45% to 65%, heat loads from 102 W to 1841 W and air flow rates from 516 m3/h to 1404 m3/h. Robust thermal performance was observed for the entire range of operating conditions. In particular, at the optimum filling ratio of 50%, minimum air flow rate of 516 m3/h and uniform heat load of 1841 W, the temperature difference between the evaporator and ambient air was less than 20 K with a COP of 102, while at the highest fan speed of 1404 m3/h this temperature difference was reduced to 8.9 K, with a reasonable CoP of 11. The test results show the high efficiency of the current hybrid air- and liquid-based cooling technology for removing heat from electronics to the ambient.

Heat Transfer Enhancement Measurement for Microfabricated Electrostatic Fluid Accelerators

Abstract: Air cooling, because of its simplicity, remains as the most popular cooling solution for microelectronics in the consumer market. However, the trend of increasing heat generation in microelectronics and the demand for compact devices result in heat fluxes approaching the limit of conventional rotary fan air cooling technology. Electrostatic fluid accelerators (EFAs), also known as electrohydrodynamic (EHD) ionic wind pumps, have the potential of becoming a critical element of electronic thermal management solutions. In this technique, application of voltage to a sharp electrode ionizes air molecules, which are propelled by the electric field, transferring part of their energy to neutral air molecules, thus creating airflow and cooling. The airflow, so called ";corona wind";, can be used discretely for hot spot cooling or integrated into a compact thermal exchange surface to decrease the fluid boundary layer and increase heat transfer enhancement. The EFA investigated in this study consists of a microfabricated AFM-cantilever corona electrode using combination of deep reactive ion etching (DRIE) and reactive ion etching (RIE), and a flat collecting electrode that doubles as the thermal exchange surface. The fabrication and testing results of a microfabricated EFA are presented in paper. Free and EFA-enhanced forced convection heat transfers are both reported by measuring the heating power difference of the collecting electrode under constant surface temperature.

Two-phase mini-thermosyphon electronics cooling, Part 1: Experimental investigation

Abstract: Efficient, small, state-of-the-art passive cooling two-phase systems, i.e. advanced micro-thermosyphon cooling systems, are viable solutions for high performance datacenter servers and power electronics cooling applications. The objective of this study is to push through the “two-phase threshold” that seems to be hindering the application of this cooling technology by offering here proven experimental results (Part 1), validated steady-state and transient simulation tools (Parts 2 and 3) and a server case study (Part 4). The experimental investigation in Part 1 presents the thermal-hydraulic performance of a mini-thermosyphon loop with a small riser height, Hriser = 15.0 cm. The thermosyphon loop has a multi-microchannel copper evaporator, mounted on top of a pseudo-chip CPU emulator (heat source). Experimental results for R134a, acquired under both pumped flow and passive thermosyphon driven flow (for direct comparison) for mass flow rates up to 10 kg/hr, uniform heat fluxes, q of up to 61.4 W/cm2 and refrigerant filling ratios up to 83% were obtained. An innovative thermal calibration method, developed as a non-intrusive mass flow measurement technique, has also been implemented to monitor the thermosyphon's operation. Summarizing in brief, the two-phase thermosyphon loop with an integrated in-line liquid accumulator offered a very sustainable cooling performance for the microchannel/pseudo-CPU package, and is a first step forward in our effort towards the integration of such two-phase passive cooling devices for data center servers and other electronic devices at heat flux of up to 80 W/cm2 (or more).