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The current investigation utilises cold spray technology to coat specimens which are experimentally tested to analyse pool boiling enhancement. The coatings are generated from a 50/50 volume aluminium/copper feedstock powder mixture that is cold sprayed onto a copper substrate. After spraying, the aluminium content is etched, using NaOH, resulting in a surface with increased surface porosity, area...
The heat transfer coefficients (HTC) on the surface of a copper disk sample during a quenching operation have been studied here. The sample is made very small so that the lumped mass approach can be applied for the measurements. Lumped heat capacitance is one of the technique, which is advantageous due to its simplicity, but it is an approximate technique to determine the HTCs, as this method assumes...
Aiming for the improvement of the boiling heat transfer coefficient, the effect of the nano-coated heating surface was investigated. We used a silane coupling agent to change the wettability of the heating surface. By means of the coated heating surface, we examined boiling curve of subcooled pool boiling. As a result, the boiling curve with the coating agent was drastically changed and microbubble...
This study evaluates boiling and evaporative heat transfer performance of a heat sink called EVAPORON-4 utilizing uni-directional porous media in order to remove high heat generation of 300–500 W/cm2 from a chip of the next generation SiC-/GaN-based on-vehicle inverter. The unidirectional porous heat sink has three functions such as direct supply of cooling liquid to a heat transfer surface, promotion...
A demand for the high performance cooling technology with low operating power exists for the thermal management of the next generation power electronics, such as the IC inverter of electric vehicle. Boiling heat transfer is a promising candidate for the cooling technology because it can remove a large amount of heat from a heat generating device by phase change of the liquid. However, it is well known...
In this paper, a heat equivalent circuit model of 300 kW class transformer coil for contactless power transfer (CPT) system is proposed to estimate coils temperature rise. This model is featured by considering the differences of the heat generation of the AC resistance loss due to the high frequency flux. It is revealed by means of this model that 10 minute operation of a 300 kW CPT transformer is...
This paper presents a new approach in modelling a photovoltaic/thermal hybrid system based on Finite Element Method (FEM). Comsol Multiphysics, a commercial simulator based on FEM, and MATLAB simulation tools are used to implement this electro-thermal model. An optimization process takes place for the water back pipes regarding its material, shape and pipe diameter for maximum conversion efficiency...
Laminated busbars acquire significant importance even if they are a passive component in converters. Their flat and overlapped conducting layers allow good heat dissipation and reduced stray inductance. Topology optimization enables balancing the amount of copper used with the maximum temperature and stray inductance of the busbar.
Phase change materials have been of increasing interest in thermal management of power batteries due to their high latent heat with minimum volume change. In this work, a numerical study of phase change materials is presented for the purpose of thermal control of the cylindrical power battery cells for applications in electric vehicles. Uniform heat density was applied at the battery cell surrounded...
The thermal behavior of an industrial Low Voltage non-segregated three-phase busduct is analyzed by means of the comparison of a 3D numerical model with experimental results. This model has been carried out using COMSOL Multiphysics, software based on finite element method. The numerical model replicates the short-circuit test, using the same geometry configuration and the boundary conditions of the...
This paper evaluates boiling heat transfer performance on a lotus-type of porous copper attached on a heated surface. The experiments are performed under atmospheric and saturated pool conditions. The lotus porous medium has uni-directional pore structure and the average size of the pore hole is 0.4 mm. The porous plate of 1.0 mm or 2.0 mm in thickness is mechanically attached onto the heated surface...
The dynamic suction process of pneumatic ejector is studied when the pressure inside the vacuum tank decreases from atmospheric pressure to extreme vacuum degree. The temperature change is one of the important parameters in the dynamic suction process of pneumatic ejector. In this study, the temperature change is analyzed by experimental approaches. The temperature is measured by the stop method....
The copper pole shields for the neutral beam lines that have been in service at DIII-D have experienced localized melting and fatigue cracks on the front faces which have migrated into the cooling tube grooves machined in the back of the copper plates, leading to water leaks. A solution was required for longer beam pulse lengths and higher beam power operation planned for DIII-D which was limited...
A novel perfusion method of micro heat pipe(MHP) is presented in this paper. The MHP has length of 26mm, width of 20 mm, and thickness of approximate 2.2mm. The predetermined quantity of perfusion is 25µl. Small volume and large capillary force render conventional vacuum perfusion methods quite impractical. In order to realize microscale and high precision of perfusion, the method of combining the...
This study demonstrates a new cooling solution for the thermal management of mobile electronics. It uses a micro loop heat pipe (μLHP) with a thickness of 0.6 mm for the evaporator and 1.0 mm for the vapor line, and is designed to fit in the casing of a smartphone. We fabricated a prototype model of the μLHP by a chemical-etching and diffusionbonding process for thin copper plates. Heat from the heatgenerating...
The local surface temperature, heat flux, heat transfer coefficient, and Nusselt number were measured for an inline array of circular normal jets of single phase liquid water impinging on a copper block. An experimental 2-D surface map was obtained by translating the jet array relative to the sensors. The effects of variation in jet height, nozzle length, and Reynolds number were investigated. The...
Mobile devices have wide functionality nowadays. The functionality of these devices is expected to be improved and expanded. However, to be able to accomplish this, power dissipation in the form of heat from major chips namely the processor, Wi-Fi, and PMU will increase. This will impose major thermal management challenges because the nature of thermal solutions in mobile devices depends on different...
This paper explores the possibility and the feasibility for using heat pipes to dehumidify the recirculated air of an air conditioning test rig. We have incorporated a circular design of heat pipes heat exchangers that is illustrated and explained in the design concept.
The electronics designing process exceeded the simple level of developing projects based on empirical approaches, when for every single change tremendous cost in time and money was spent in most of the cases. Moving the design process from the real to the virtual world changed the engineering perspective on what can be done in less time. As previous discussed [9], [12], signal integrity and power...
The formation analysis of the 15-beam 14 kW klystron collector was made. The distribution of specific beam loads on the collector surface was obtained. Three-dimensional heat problem in the approximation of the surface effective heat transfer coefficient was solved and collector temperature field obtained.
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