Effects of Particle Stacking Angle on Heat Transfer Characteristics of Particles Close to the Wall

The primary energy demand increases, but a large amount of waste heat resources were not effectively used. To explore the influence of particle stacking structure on waste heat recovery process, CFD method was used to simulate. An unsteady heat transfer model of two particles was established, effect of particle stacking angle on heat transfer characteristics of the particles close to the wall under different initial temperature conditions was studied. Results show that: higher initial temperature, resulting in increased heat transfer time, the larger particle stacking angle causes the shortening of heat transfer time. When initial temperature is 1073 K, the average wall heat flux shows a trend of rapid decline first and then a slow one. At the same moment, the larger stacking angle causes smaller particle average temperature. The change of particle stacking angle shows a greater impact on the temperature of the particles close to adiabatic wall. The increase in the stacking angle resulting in better heat transfer characteristics between particles.

Effects of Heat Exchange Tube Structural Parameters on Performance of Vehicle Radiator

In order to improve the performance of vehicle radiators, a two-dimensional heat transfer steady-state model of the radiator was set up. The influence of the structural parameters (axial ratio) of the heat exchange tube on the windward side on the heat transfer performance of the radiator was studied. With the increase of the axial ratio of the heat exchange tube on the windward side, the heat exchange capacity of the heat exchange tube surface slightly decreases. The heat exchange area increases significantly, which increases the total heat exchange of the radiator and improves the heat transfer performance of the radiator. When the axial ratio increases from 1.0 to 2.0, the average surface heat transfer capacity decreases from 5664.16 W/m2 to 5623.57 W/m2.

Effects of Different Sowing and Transplanting Time on Quality and Economic Benefit of Tobacco Variety Yunyan 105

In order to provide references for popularization and application of tobacco variety Yunyan 105,a field experiment was conducted to explore the effects of different sowing and transplanting time on agronomic traits,economic benefit and quality of Yunyan 105. Results showed that the agronomic characters,quality traits and economic benefit of the tobacco were relatively fine with sowing time February 4-14 and transplanting time April 1-10. Index scores of the physical properties of tobacco leaves were greater than 80 scores with sowing time February 14 and transplanting time April 10. The comprehensive index of conventional chemical compositions was 0. 39-0. 73. The harmony of conventional chemical compositions of lower leaves was the best with the comprehensive index of 0. 59 when the sowing time and transplanting time were February 4 and April 1 respectively. As for the middle and upper leaves the comprehensive indexes were respectively 0. 71 and 0. 73 with the sowing time February 14 and transplanting time April 10. The sensory evaluation of smoking quality and economic benefit were February 14 sowing and April 10 transplanting better,its taste of the tobacco leaves was pure and mild,the irritancy and the strength was less,the aftertaste was better,and the output value reached the highest 4 271. 17 yuan/667 m^2. The various sowing and transplanting time had no significant influence on appearance quality of tobacco leaves. The suitable sowing and transplanting time of Yunyan 105 was February 4-14 and April1-10 respectively in Xuanwei tobacco-growing area.