No abstract

No abstract

No abstract

Purpose The purpose of this study is to use an electric field technique to design novel heat sinks capable of rejecting as much heat as possible in a limited space. Configuration of electrodes in this study can be used for increasing the efficiency of heat sinks. Design/methodology/approach This study investigates a novel electrohydrodynamic (EHD)-based heat sink for thermal management of electronic devices and thermal systems. The significant part of designing an EHD heat sink is the arrangement of the electrodes. A numerical simulation is performed for a heat sink with two parallel plates to determine the optimum dimensional configuration of electrodes. The upper plate of this heat sink is the ground electrode with a constant atmosphere temperature, and the lower plate of it with flush-mounted high-voltage electrodes has uniform heat flux. Findings The results show that heat transfer changes by the size of the vortices and the number of them. These vortices are emerged by the electric field, and the number of them increases with increasing the number of electrodes. The interaction of vortices size and number leads to having the lowest average temperature in the optimum case by two high voltage electrodes with widths of 7.5 mm and a 17.5 mm gap between them. In comparison with the case without the electric field, with increasing the applied voltage to 30 kV, the efficiency of this EHD heat sink increases up to 37%. Originality/value Improvements in electrical equipment make them more compact with higher heat fluxes. Hence, the amount of heat to be dissipated per area increases and needs thermal management to operate at their design temperatures. Therefore, to improve the performance and life span of electronic components and increase their efficiency, it is necessary to design heat sinks to decrease their maximum (peak) temperature.

No abstract

The application of Thermoelectric Generators for converting geothermal energy to electricity is investigated in this paper, considering the effects of various parameters on their efficiency. Using renewable energy is one of the latest solutions to tackle climate change, global warming, air pollution, the ozone layer hole, etc. In this regard, a thermoelectric generator (TEG), which is a device for converting heat energy to power, could be used in different renewable energy systems like solar or geothermal. Although their initial cost is lower than the other methods of converting thermal energy to electricity, their efficiency is lower than the most common techniques. Therefore, finding the optimum situation to increase the efficiency of combined devices with TEGs can increase the likelihood of using them in different industries. The parameters investigated in this paper were the temperature of the operating fluid in channels, the optimum mass flow rate, and the channel slope. The results have shown that with increasing temperature differences of the fluid in the channel, the efficiency of the designed system increased significantly. In addition, by increasing the mass flow rate of the operating fluid in the channel, power generation and the whole system efficiency increase up to a certain plateau value. Furthermore, the experimental results have proven that increasing the slope of the channel increased the amount of power generation but has not caused a noticeable change in their efficiency.