Experimental investigation of a solar collector integrated with a pulsating heat pipe and a compound parabolic concentrator

Abstract

The paper reports an experimental investigation of a newly proposed solar collector that integrates a closed-end pulsating heat pipe (PHP) and a compound parabolic concentrator (CPC).The PHP is used as an absorber due to its simple structure and high heat transfer capacity. The CPC has a concentration ratio of 3.4 and can be readily manufactured by three-dimensional printing. The CPC can significantly increase the incident solar irradiation intensity to the PHP absorber and also reduce the heat loss due to the decrease in the area of the hot surface. A prototype of the solar collector has been built, consisting of a PHP absorber bent by 4 mm diameter copper tube, CPC arrayed by 10×2 CPC units with the collection area of 300×427.6 mm 2 , a hot water tank and a glass cover. HFE7100 was utilized as the working fluid at a filling ratio of 40%. The operating characteristics and thermal efficiency of the solar collector were experimentally studied. The steady and periodic temperature fluctuations of the evaporation and condensation sections of the PHP absorber indicate that the absorber works well with a thermal resistance of about 0.26 ℃/W. It is also found that, as the main factor, the thermal performance of the collector decreases with increasing evaporation temperature. The collector apparently shows start-up, operational and shutdown stages at the starting and ending temperatures of 75 °C. When the direct normal irradiance is 800 W/m 2 , the instantaneous thermal efficiency of the solar collector can reach up to 50%.

A Review of the Compound Parabolic Concentrator (CPC) with a Tubular Absorber

“…The collector has the advantages of both the heat pipe and the CPC, i.e., fast response and higher temperature [39]. A CPC with a closed-end pulsating heat pipe (PHP) has also been reported, which could achieve more stable performance on rainy days [40].…”

“…The collector has the advantages of both the heat pipe and the CPC, i.e., fast response and higher temperature [39]. A CPC with a closed-end pulsating heat pipe (PHP) has also been reported, which could achieve more stable performance on rainy days [40]. Zhu et al [41] proposed a solar air collector that uses flat micro-heat pipe arrays (FMHPA) as the absorber of the CPC (Figure 19).…”

Building integrated solar concentrating systems: A review

“…Fig. 18 [46] shows the structure of the typical CPC with the heat pipe located in the base center for the concentrating solar thermal application. The involute of the CPC is expressed as:…”

Strategies to improve the thermal performance of heat pipe solar collectors in solar systems: A review

“…Also, the designed CPC-HPSCs was recommended for medium temperature applications as it improved collection efficiency and decreased response time. Xu et al [84] proposed the new combination of CPCs with closed-end pulsating HPSCs and studied its performance experimentally. The main aim of the new design was to enhance solar radiation intensity and also to reduce the heat losses.…”