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Experimental investigation on efficient heat collection of aboveground pipes

ABSTRACT
Prospects for low-cost utilization and storage of solar energy are promising. In this study, the change of shallow geo-temperature was monitored, and the influence of solar radiation on shallow geo-temperature was discussed. Three series of field experiments on heat transfer of aboveground pipes were designed, and the variations of water temperature in the aboveground pipes were also monitored. According to the experimental data, the relevant factors affecting the water temperature inside the pipe (such as solar radiant intensity, pipe's material, pipe's spatial location, heat-accumulating wall and so on) were analyzed. Based on the field test, a three-dimensional model of aboveground pipe heat transfer was established to verify and temperature prediction was carried out. The results show that the water temperature in the pipe is most significantly affected by solar radiation, and is also related to the color of the pipe and its spatial position; The water temperature of galvanized steel pipe wrapped with black plastic film is the highest under solar radiation, and the optimum distance between the pipe and the heat-accumulating wall and the earth's surface is respectively 0.90 ~ 1.25 times of the outer diameter of the pipe; The way the pipe is covered has a great influence on the water temperature inside the pipe. When the black PE pipe covered with the white plastic film is in the best spatial position, the highest heat of the three series of tests is obtained, and the difference between the water temperature inside the pipe and the atmospheric temperature reaches 36.3°C.
KEYWORDS
PAPER SUBMITTED: 2019-07-27
PAPER REVISED: 2019-10-13
PAPER ACCEPTED: 2019-10-28
PUBLISHED ONLINE: 2019-11-17
DOI REFERENCE: https://doi.org/10.2298/TSCI190727423W
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