Electronics cooling

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

Operating controls and dynamics for floating refrigerant loop for high heat flux electronics

Abstract: The Oak Ridge National Laboratory (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) have been developing technologies to address the thermal issues associated with hybrid vehicles. This work is part of the ongoing FreedomCAR and Vehicle Technologies (FCVT) program, performed for the Department of Energy (DOE). Removal of the heat generated from electrical losses in traction motors and their associated power electronics is essential for the reliable operation of motors and power electronics. As part of a larger thermal management project, which includes shrinking inverter size and direct cooling of electronics, ORNL has developed U.S. Patent No. 6,772,603 B2, Methods and apparatus for thermal management of vehicle systems and components (Hsu et al, 2004), and patent pending Floating loop system for cooling integrated motors and inverters using hot liquid refrigerant (Hsu et al, 2004). The floating-loop system provides a large coefficient of performance (COP) for hybrid drive component cooling. This loop uses R-134a as a coolant and shares the vehicle's existing air-conditioning (AC) condenser, which dissipates waste heat to the ambient air. Because temperature requirements for cooling power electronics and electric machines are not as low as that required for passenger compartment air, this adjoining loop can operate on the high-pressure side of the existing AC system. This arrangement also allows for the floating loop to run without a compressor and requires only a small pump to move the liquid refrigerant. For the design to be viable, the loop must not adversely affect the existing system. The loop should also, ideally, provide a high COP, a flat temperature profile, and low pressure drop. To date, the floating-loop test prototype has successfully removed 2 kW of heat load in a 9 kW automobile passenger AC system with and without the automotive AC system running. However, during the cyclic operation of the floating refrigerant loop, some two-phase transient behavior is evident. In order to maintain stable running conditions, specific operating controls were implemented. Also thermodynamic energy balances were conducted to further analyze the operating conditions

Study on Application of Heat Pipe Radiator in High Power LEDs for Street Lamp

Abstract: Heat pipe radiator was experimental and numerical studied to solve the cooling problem of high power LEDs for street lamp. Firstly,the surface temperature of the lamp housing was measured by IR sensor then surface temperature of the heat pipe radiator was also measured. Experimental results show that the average temperature of the heat pipe radiator is about 38 ℃ and the distribution is even. So heat pipe radiator is applicable for high power LED street lamp and is one of the methods for solving the heat dissipating problem. Secondly,a mathematical model was built to simulate the distribution characteristics of the flow and temperature fields. Simulation results agree well with the experimental results and therefore the model is proved to be reliable. The results also suggest that there are several disadvantages of the heat dissipation fins. Optimizing designs and methods are discussed and put forward finally.

Numerical Simulation of the Fan Cooling Effect on a 10000t/d Cement Rotary Kiln

Abstract: Industry production practice and CFD (Computational Fluid Dynamics) numerical simulation technology are integrated together in the study of the fan cooling effect on an overseas 10000t/d (ton/day) cement rotary kiln. The spot data of a 10000t/d cement production at home were collected and studied, which provided the vital data for numerical simulation of the fan cooling effect. Then aiming at the working ambient conditions of the overseas 10000t/d cement production line, the fan cooling effect of its rotary kiln was numerically simulated by considering natural convection and radiation heat-loss. Finally, based on the results of the simulation, a conclusion is drawn that the fan cooling effect is good enough to make the overseas rotary kiln safely run at its ambient conditions.

Modern research about electronics cooling method

Abstract: Electronics cooling method is a major concern in thermal design.This paper presents some cooling methods mainly used for large heat flux electronics.Some new promising methods are presented here too in order to attract domestic researchers.

Multi-Evaporator Closed Loop Thermosyphon

Abstract: A novel type of multi-evaporator Closed-Loop Two-Phase Thermosyphon has been designed and tested at different inclinations and heat input levels. The device consists in an aluminum tube (I.D./O.D. 3/5 mm), bended into a planar serpentine with five U-turns in the heated zone, with a 50 mm transparent section for the purpose of visualization. The tube is closed in a loop, evacuated and partially filled with FC-72, 50% vol. Each turn is equipped with an electric wiring heater and the peculiar location of the heating sections causes the fluid to circulate regularly in a preferential direction. The condenser zone is embedded into a heat-sink and cooled by fans blowing air at 20 °C. Sixteen T-type thermocouples are located on the external tube wall in the evaporator and condenser zones, while the fluid pressure is measured in the condenser zone adjacent to the transparent tube. The flow pattern is recorded by means of a high-speed camera, the device operational limits (start-up and dry-out heating levels at the different inclinations) are detected and the overall thermal performance is calculated for different inclination angles and heat power inputs. Thanks to the fluid flow motion stabilization in a preferential direction due to the peculiar position of the heating elements, in vertical position the device is able to dissipate heat fluxes higher than 57% with respect to the CHF limit for FC-72, keeping also the temperatures at the evaporator zone lower than 80 °C. INTRODUCTION Two phase heat transfer devices have always been attractive for their compactness, high performance and, above all, the possibility of being completely thermally driven (passive). The increasing need of managing high heat fluxes, either to be dissipated (electronics cooling) or to be recovered (solar concentrators), drives toward the design of more efficient and reliable devices. Despite the last decades witnessing the overwhelming spread of the heat pipe technology under various forms such as grooved and sintered heat pipes, loop heat pipes and capillary pumped loops, the interest in wickless, gravity driven technologies, namely the Two Phase Thermo-Syphons (TPTS), never damped out. The capability to transport heat at high rates over appreciable distances, without any requirement for external pumping devices, the low cost, durability and relatively simpler modeling/design process make this technology very attractive for many thermal management applications. Indeed, TPTS have been investigated in plenty of fields such as: nuclear plants (Lahey and Moody 1993), energy systems (Franco and Filippeschi 2013), solar heat recovery (Esen and Esen, 2005), (Li et al. 2014), (Moradgholi et al. 2014), air conditioning (Han et al. 2013), electronic cooling in avionics (Sarno et al. 2013) and in railway traction (Perpina et al. 2007). The typical TPTS (Reay and Kew 2006) consists of a single envelope where the heat-receiving (evaporator) zone is usually filled with the liquid phase and it is located below the heat rejecting (condenser) zone. As the evaporator zone is heated up, the liquid starts boiling and vapor rises and condenses on the walls in the heat-rejecting zone. The liquid film flows down by gravity the walls to the evaporator zone counter-current the vapor. At high heating power input, because of the correspondingly large mass flow rate of the vapor, the liquid-vapor interfacial shear stress becomes increasingly relevant. Once the interfacial shear force overcomes the gravitational force on the liquid film, the liquid flow may be reversed and the flooding limit is reached. Many novel designs have been proposed to overcome the flooding limit, which include an internal physical barrier along the adiabatic section by-pass line for liquid return, a cross-over flow separator. The main advantage of these designs is that the liquid and vapor flows have partially separated passages, which can result in a higher floodinglimited heat transfer capacity. Another way to separate phases and increase the device performance is to create a loop where 7 European-Japanese Two-Phase Flow Group Meeting Hotel Beau Site, 11-15 October 2015 Zermatt, Switzerland