微通道对复合抛物聚光面非均匀热流密度均化作用的实验研究

Experimental study on homogenization of composite parabolic concentrator nonuniform heat flux by microchannels

中文关键词: 微通道  复合拋物聚光面  运行特性  不均匀度

英文关键词: Microchannel  Compound parabolic concentrator  Operating characteristics  Non-uniformity

中文摘要:

      聚光集热器可在相同集热面积下获得更高的集热温度，但会在吸热器表面形成不均匀的热流密度分布，这会影响吸热器寿命及集热器的高效稳定运行。微通道平行流扁管具有较高的对流换热系数，可减小温度梯度，均化非均匀的热流密度。提出了以微通道平行流扁管作为吸热器、CPC（复合抛物聚光面）作为聚光器的太阳能集热器，设计并搭建了实验测试系统，研究了不同入口水温、流量、入射角度等工况下，微通道对CPC产生的非均匀热流密度的均化作用。实验结果表明，随着集热流体入口水温的升高、流量增大、光线入射角增大，微通道吸热器进出口温升均会降低。随着光线入射角的增大，微通道吸热器表面热流密度分布不均匀度增加，由直射时的0.90增加至入射角为18°时的1.40。实际微通道出口各流道温度分布与微通道上表面热流密度分布基本吻合，微通道出口截面温度分布不均匀度不超过0.045，出口截面的最大温差低于3.57 ℃，微通道均化作用明显。研究为解决聚光集热器导致的非均匀热流密度问题及CPC集热器设计提供了参考。

英文摘要:

      The collector can obtain higher heat collecting temperature under the same heat collecting area, but the collector will form uneven heat flux distribution on the surface of the collector, which will affect the life of the collector and the efficient and stable operation of the collector. Microchannel flat parallel flow tube has high convective heat transfer coefficient, which can reduce temperature gradient and homogenize non-uniform heat flux. A solar collector with CPC (composite parabolic concentrator) as concentrator was proposed. An experimental test system was designed and built to study the homogenization effect of microchannel on the non-uniform heat flux generated by CPC under different inlet water temperature, flow rate and incident angle. The experimental results show that the temperature rise of inlet and outlet of the microchannel heat absorber decreases with the increase of inlet water temperature, flow rate and ray incidence angle. With the increase of the incident angle, the non-uniformity of the surface heat flux distribution increases from 0.90 when the incident angle is 0° to 1.40 when the incident Angle is 18°. The actual temperature distribution of each channel outlet is basically consistent with the heat flux distribution on the upper surface of the micro-channel. The actual temperature distribution of each channel outlet is basically consistent with the heat flux distribution on the upper surface of the microchannel. The temperature distribution inhomogeneity of the microchannel outlet section is less than 0.045, and the maximum temperature difference of the outlet section is less than 3.57 ℃, indicating obvious homogenization of the micro-channel. The research provides a reference for solving the problem of non-uniform heat flux caused by collector and the design of CPC collector.