| Energy is an essential material basis for human survival and development,and also an important factor restricting economic and social development.Energy saving and emission reduction has become the best choice for green sustainable development of all countries.Among the energy consumption of various industries in China,industrial energy consumption ranks first,more than half of which are transformed into industrial waste heat of di fferent carriers and different temperatures.If this part of waste heat is effectively used,it will play a positive role in improving industrial economic efficiency and building a strong ecological civilization.However,in the process of waste heat recovery of high-temperature particles,particles have the characteristics of irregular shape,rough surface,and poor fluidity,resulting in vacanc y caused by friction and extrusion collision between particles.T he vacancy increases the heat transfer resistance of the particle pile and reduces the efficiency of waste heat recovery.Based on the one-time waste heat recovery method,a heat transfer model for double vacancy particle under regular arrangement was established and simplified,and particle pile heat transfer experimental bench was set up.T he typical experiments of no vacancy and double vacanc y conditions were carried out,and the availability of the heat transfer model was verified,and numerical simulation of double vacanc y particles was carried out by using the heat transfer model.T he effects of the change in the position and spacing of vacancy in a double vacancy particle pile array with a 45 ° arrangement perpendicular to the heat flow direction,parallel to the heat flow direction was s tudied.T he main results were as follows:(1)T he existence of double vacanc y hinders the heat transfer of the particle pile.T he closer to the location of the vacancy,the more obvious the particle temperature and heat fluctuations.T he heat transfer path ways near the vacancy mainly include solid/solid direct contact between the particles along the X and Y directions,gas/solid between the particles and the gas phase,gas/gas heat conduction at the vacancy,and radiant heat transfer.Among them,the solid / solid heat conduction along the Y direction is the mainstream heat transfer method.T he simulation results show that the interaction between double vacancy can be ignored when the space bet ween double vacancy is more than or equal to 4 times the particle size.(2)In the direction perpendicular to the heat flow,as the double vacancy move from the cold wall to the hot wall,the influence range of the vacancy also moves.Affected by the wall,the temperature of double vacancy at the cold and hot wall changes the most greatly than that at other locations,and the total heat transfer quantity presents a "U-type" change trend,with the maximum value at the R1C10(Row initial R for row,Column initial C for column,R10C10 stands for the vacancy position in row 10,the same below)and R1C11 is 32.47 W.T he contribution degree curve of solid heat transfer on the wall is low and flat at both ends,and keeps at 99.69%.T he apparent thermal resistance shows a "inverted U-type" change trend,reaching the minimum value close to the heat exchange wall at 11.54 ? /W.With the increase of the number of the gap size,the interaction degree of the two vacanc y is weakened,the local influence scope is reduced,but the overall influence scope is increased.When the gap is 0 time s of particle size,the maximum heat transfer is 32.32 W,and the minimum apparent thermal resistance is 11.60? /W.When the gap is increased from 1 time of particle size to 4 times of particle size,the heat transfer increases,the contribution of solid-phase heat transfer remains unchanged,and the apparent thermal resistance decreases.(3)In the direction parallel to the heat flow,as the double vacancy move from the cold wall to the hot wall,the influence range of the vacancy also moves.Affected by the wall,the temperature of double vacanc y at the cold and hot wall changes the most greatly than that at other locations,and the total heat transfer quantity presents a "U-type" change trend,with the maximum value at the R1C10-R1C11 is 32.59 W.T he contribution degree curve of solid heat transfer on the wall is low and flat at both ends,and keeps at 99.69%.The apparent thermal resistance shows a "inverted U-type" change trend,reaching the minimum value close to the heat exchange wall at 11.41 ? /W.With the increase of the number of the gap size,the interaction degree of the two vacanc y is weakened,the local influence scope is reduced,but the overall influence scope is increased.When the gap is 0 times of particle size,the maximum heat transfer is 32.71 W,and the minimum apparent thermal resistance is 11.46 ? /W.When the gap is increased from 1 time of particle size to 4 times of particle size,the heat transfer increases,the contribution of solid-phase heat transfer remains unchanged,and the apparent thermal resistance decreases.(4)In the direction of 45° with the direction of heat flow,as the double vacancy move from the cold wall to the hot wall,the influence range of the vacancy also moves.Affected by the wall,the temperature of double vacanc y at the cold and hot wall changes the most greatly than that at other locations,and the total heat transfer quantity presents a "U-type" change trend,with the maximum value at the R1C10-R1C11 is 32.69 W.T he contribution degree curve of solid heat transfer on the wall is low and flat at both ends,and keeps at 99.69%.T he apparent thermal resistance shows a "inverted U-type" change trend,reaching the minimum value close to the heat exchange wall at 11.47? /W.With the increase of the number of the gap size,the interaction degree of the two vacancy is weakened,the local influence scope is reduced,but the overall influence scope is increased.When the gap is 0 times of particle size,the maximum heat transfer is 32.30 W,and the minimum apparent thermal resistance is 11.61 ? /W.When the gap is increased from 1 ti me of particle size t o 4 times of particle size,the heat transfer increases,the contribution of solid-phase heat transfer remains unchanged,and the apparent thermal resistance decr eases. |
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