Electronics cooling

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

Loop Heat Pipes for Cooling Systems of Servers

Abstract: Loop heat pipes (LHPs) are exceptionally efficient heat-transfer devices that employ a closed loop evaporation-condensation cycle that can be used to cool densely packed electronic systems that reject large quantities of heat, including computers and their central processing units (CPUs). Tests were carried out on miniature ammonia LHPs with a CPU thermal simulator using different ways of condenser cooling. The possibility of maintaining the cooled object temperatures between 40°C and 70°C with heat load changing from 100 to 320 W was demonstrated. Subsequent tests of these devices in a 1U computer with dual core advanced micro devices Opteron CPUs, dissipating between 95 and 120 W, have confirmed the advantages and heat transfer efficiency of LHP-based cooling systems used to cool CPU in 1U chassis.

Extending the limits of air cooling with thermoelectrically enhanced heat sinks

Abstract: The prospects of using thermoelectric coolers (TECs) as a means to enhance heat sink performance and extend the limits of air cooling for electronics has considerable appeal when one considers the alternatives of liquid cooling. Historical analyses of TECs for electronics cooling only considered "off-the-shelf" TECs, resulting in poor performance predictions and in many cases system performance that was better without the TEC. This poor performance has been taken as typical and hopes of improved performance tied only to new, more efficient bulk thermoelectric materials and future thin film thermoelectric material formats. This paper demonstrates the results possible when today's best bulk thermoelectric materials are utilized in optimum TEC designs eliminating the penalty imposed by using non-optimum "off-the-shelf TECs. These optimized TEC configurations can provide an effective negative thermal resistance while operating at high COP thereby extending the limits of traditional air cooling for electronics.

Electrohydrodynamic Microfabricated Ionic Wind Pumps for Thermal Management Applications

Abstract: This work demonstrates an innovative microfabricated air-cooling technology that employs an electrohydrodynamic (EHD) corona discharge (i.e., ionic wind pump) for electronics cooling applications. A single, micro fabricated ionic wind pump element consists of two parallel collecting electrodes between which a single emitting tip is positioned. A grid structure on the collector electrodes can enhance the overall heat-transfer coefficient and facilitate an IC compatible batch process. The optimized devices studied exhibit an overall device area of 5.4 mm × 3.6 mm, an emitter-to-collector gap of ~0.5 mm, and an emitter curvature radius of ~12.5 μm. The manufacturing process developed for the device uses glass wafers, a single mask-based photolithography process, and a low-cost copper-based electroplating process. Various design configurations were explored and modeled computationally to investigate their influence on the cooling phenomenon. The single devices provide a high heat-transfer coefficient of up to ~3200 W/m 2 K and a coefficient of performance (COP) of up to ~47. The COP was obtained by dividing the heat removal enhancement, ΔQ by the power consumed by the ionic wind pump device. A maximum applied voltage of 1.9 kV, which is equivalent to approximately 38 mW of power input, is required for operation, which is significantly lower than the power required for the previously reported devices. Furthermore, the microfabricated single device exhibits a flexible and small form factor, no noise generation, high efficiency, large heat removal over a small dimension and at low power, and high reliability (no moving parts); these are characteristics required by the semiconductor industry for next generation thermal management solutions.

Loop heat pipe technology for cooling computer servers

Abstract: An air cooled loop heat pipe (LHP) system was developed for cooling a dual CPU 1U server. The LHP uses newly developed flat plate evaporators and air cooled condensers with millimeter scale condensation channels and plain parallel fins. Bench tests were conducted using 20 x 20 mm uniform heat sources dissipating 100 watts and air preheating to simulate air-cooled operation within a 1U server chassis. Thermal resistance was decreased as the air temperature increased from 25degC to 50degC. At 50degC air temperature, the LHP evaporator surface temperature reached 65degC showing an effective evaporator surface to air thermal resistance of 0.15degC/W. A commercial 1U server with dual 100 W rated Intel Xeon processors was used to compare the effectiveness of the LHP cooling system to the standard processor fan heat sinks. Multiple instances of CPU Burn were used to exercise the CPU's for maximum power dissipation. Under similar test conditions with room air temperature in the range 26-30degC, the interface temperature at the processors stabilized at ~75degC with the fan heat sinks and ~55degC with the LHP cooling system.

Thermal management of single and multiple PCMs based heat sinks for electronics cooling

Abstract: The present study focuses on passive thermal management of electronic devices using heat sinks embedded with single or multiple phase change materials (PCMs) RT58, RT44 and n-Eicosane are used as PCMs, while aluminium fins are used as thermal conductivity enhancer (TCE) Single PCM cases are investigated independently while multiple PCMs pairs are studied through their filling in alternate enclosures separately Three constant heat fluxes of 15, 25 and 35 kW/m2 are applied to the heat sinks to investigate PCMs’ thermal performance The numerical model is validated against available experimental results where an acceptable 29% difference in the transient temperature is achieved High values of Nusselt number were discovered at the beginning of melting and the end of solidification stages The RT44 shows the lowest peak temperature and longest melting duration among single PCM cases, due to its high latent heat of fusion When n-Eicosane and RT44 are paired in a heat sink, the best overall thermal performance is achieved where its operational time is increased by 33–12% comparing to single n-Eicosane or RT44 The results show that the multiple PCMs pair of n-Eicosane/RT44 is feasible for high critical temperature devices due to its longer operating time and also lowest average transient temperature