一种强化太阳能换热的新型涡流发生器换热机理与实验研究

HEAT TRANSFER MECHANIISM AND EXPERIMENTALINVESTIGATION OF A NEW VORTEX GENERATORENHANCING HEAT EXCHANGE OF SOLAR ENERGY

提出一种强化太阳能热风干燥器和集热器气侧换热的新型涡流发生器—斜截半椭圆柱体,并对其进行了实验研究及机理分析。在雷诺数为4000～38000的紊流范围内对矩形风道内分别布置单排一对直角三角翼、矩形翼、梯形翼、斜截半圆柱体、斜截半椭圆柱体等涡流发生器的强化传热效果和压降特性进行了对比实验。实验在稳态的气水逆流换热方式下进行,并固定各涡流发生器的高宽比为1/2,该迎流攻角为60°。结果表明,斜截半椭圆柱体是具有优越的强化气侧换热效果和低压降特性的新型涡流发生器。该对这种新型涡流发生器强化换热的机理作了初步分析。

The paper puts forward a new-type vortex generator enhancing heat exchange of solar air-drier and air-heater on the gas side and makes experiment and mechanism analyses have been presented.Experiments were done to contrast the heat tansfer enhancement and pressure loss caused by several single-pare vortex generators(VGs) such as delta winglets,rectangular winglets,trapeze winglets,bevel-cut half-cylinder VG and bevel-cut half-elliptical column VG,which were installed in a rectangular tunnel respectively.Turbulent flow( Re =4000～38000) was considered and steady gas-water heat exchange with converse direction was adopted in the experiments.The same ratio of height to width( h/b =1/2)and the same angle of attack ( β =60°) are considered for all of the VGs.The results showed that the bevel-cut half-elliptical column is a new kind of VG which enhances heat transfer more effectively and cause less pressure loss than the others.An elementary analysis was also made on the mechanism of heat transfer enhancement by the new vortex generator.