1,721,239 research outputs found
Wettability, gravity and electric field effects on local heat flux at triple line
No full textabstrac
Pulsating Heat Pipes with Flexible Adiabatic Section: First Experimental Results
No full textThis paper shows some preliminary experimental results of a single turned PHP operating in a vertical mode with the condenser and the evaporator connected with flexible pipes. The inner diameter of these pipes is 2 mm and the working fluid used in the experiments is water. For each test a high speed imaging acquisition has been carried out. In this experiments no misalignment between evaporator and condenser has been tested. Thermal resistances of 1.96-2.80 K/W have been observed. The experiments have shown which the flexible pipes make unsymmetrical the device so that a preferential direction in the circulation has been observed. Four different steady regimes have been observed equal to those highlighted in similar devices. The most common operative regime is characterized by alternating periods of fluid circulation and periods without any circulations, while the steady state without any stationary period have been rarely observed. The flow patterns of the water PHP show small vapour plugs which are long as the inner diameter of the capillary pipes. This behaviour could be induced by the flexible pipe
Experimental analysis of the melting process in a pcm/aluminum foam composite material in hypergravity conditions
No full textPhase change materials [(PCMs), e.g., paraffin waxes, fused silica salts, and polyethylene glycol] can be successfully used for thermal management and heat storage in ground and space applications. Open-cell metal foams embedded in the PCM material increase the overall thermal conductivity and accelerate the melting process. The literature shows that the pore size and relative density strongly affect the melting process performance. Most studies have shown that the high thermal conductivity of the open-cell metal foam dominates the melting process. The natural convection effect usually is attenuated; however, it can be relevant if it occurs. An experimental activity has been designed and carried out under the framework of the European Space Agency student program Spin Your Thesis 2017 to analyze the effect of different hypergravity levels and configurations on the melting performance of a composite aluminum foam (10 pores per inch)/paraffin wax material at two different heat fluxes. The gravity level ranges from 5g up to 20g using a large diameter centrifuge facility. The effect of gravity on the melting process has been investigated by measuring the melting time and the dynamic evolution of the melted area. The experiments show that the hypergravity condition accelerates the melting process: it is 12% faster ranging from 5g to 10 g. Infrared visualization allowed us to define the melting front dynamic evolution. A natural convection regime was observed in all of the experiments. The natural convection incipience accelerates the melting process. A critical analysis of the scaling criterion in the literature has been qualitatively done and a modified Rayleigh number is proposed to characterize the melting process
Intracranial hypertension resistant to treatment. A case report
No full textIntracranial hypertension determines reduction of cerebral blood flo
Heat transfer and flow field in a submerged slot jet of water impinging on a circular cylinder
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