太阳能增强型间接空冷塔流动换热特性及其受环境侧风的影响机制

FLOW AND HEAT TRANSFER CHARACTERISTICS OF SOLAR-ENHANCED INDIRECT DRY COOLING TOWER AND ITS MECHANISMS INFLUENCIED BY ENVIRONMENTAL CROSSWIND

通过建立太阳能增强型间接空冷塔的三维数值模型,从塔内外流场、温度场分布以及塔内不同高度层空气温度、速度的趋势变化剖析太阳辐射对塔流动换热的增效作用以及受环境侧风影响后的变化规律,并与传统间接空冷塔的性能变化进行对比分析。结果表明:太阳辐射的引入降低了侧风对间接空冷塔流动换热的不利影响,具体为减弱塔内涡流及提升塔侧风区、背风区换热器的进气与散热能力。在无风和低风速下,太阳能增强型间接空冷塔在地面和集热器附近的空气速度、温度均高于传统间接空冷塔,且地面附近空气受太阳辐射影响更大,其温升更高,而中间高度层上空气温度会稍小于传统间接空冷塔;高风速下,受塔内涡流影响,太阳能增强型间接空冷塔内背风区的进气温度沿径向呈下降趋势。侧风下太阳能增强型间接空冷塔的通风量与散热量均要高于传统间接空冷塔,最大分别提升10.5%和5.8%,且其对环境侧风的敏感度要小于传统间接空冷塔。

With a well-developed three-dimensional numerical model of the solar-enhanced indirect dry cooling tower(IDCT),the effects of solar radiation on fluid flow and heat transfer of the tower and the varying mechanisms caused by the environmental crosswind were evaluated.The distributions of the air flow and temperature fields inside and outside the tower,as well as the varying trends of the air temperature and velocity at different altitudes inside the tower were exported and analyzed.The performance comparison was carried out between the traditional and solar-enhanced IDCTs.The results showe that the introduction of solar radiation helps to mitigate the adverse impact of crosswind on fluid flow and heat transfer of the IDCT,especially reducing the vortexes inside the tower and improving the air intake and heat dissipation capacity of the sideward and leeward heat exchangers of the tower.Under no crosswind and low crosswind speed conditions,the internal air velocity and temperature near the ground and the collector of the solar-enhanced IDCT are higher than those of the traditional IDCT.The internal air near the ground gets more affected by solar radiation and has a higher temperature rise,while the internal air temperature at the middle altitude between the ground and the collector is slightly lower than that inside the traditional IDCT.At high crosswind speed,internal air temperature inside the leeward region of the solar-enhanced IDCT decreases along the radial direction of the tower due to the great internal vortex.The ventilation and heat dissipation rates of the solar-enhanced IDCT under crosswind are higher than those of the traditional IDCT with a maximum increase of 10.5%and 5.8%,respectively.Besides,compared with the traditional IDCT,cooling performance of the solar-enhanced IDCT is less sensitive to environmental crosswind.