Experimental study on geothermal heat exchangers buried in diaphragm walls

• Published in: Energy and buildings Vol. 52; pp. 50 - 55
• Main Authors: Xia, Caichu, Sun, Meng, Zhang, Guozhu, Xiao, Suguang, Zou, Yichuan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.09.2012; Elsevier
• Subjects: Applied sciences; Building technical equipments; Buildings; Buildings. Public works; Earthwork. Foundations. Retaining walls; Energy; Energy geotechnical engineering; Energy management and energy conservation in building; Environmental engineering; Exact sciences and technology; Geotechnics; Geothermal energy; Geothermal heat exchangers buried in diaphragm walls; Ground source heat pump; Heat transfer performance test; Natural energy; Water collecting, well, pumping; Water supply. Pipings. Water treatment; INW, China, People's Rep., Shanghai; Geothermal heat exchangers buried in diaphragm walls; Heat transfer performance test; Energy geotechnical engineering; Ground source heat pump; Performance evaluation; Diaphragm wall; Heat pump; Buried construction; Geothermal energy; Climatic engineering; Experimental study; System description; Heat exchanger; Comparative study; Heat transfer
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2012.03.054

► Conducting the first field experiment of heat exchangers in diaphragm wall. ► Finding the difference between heat exchanger in diaphragm wall and in borehole. ► Investigating the influence of 4 factors on heat exchange rate in diaphragm wall. To bury absorber tubes in diaphragm wall as heat exchanger is a new energy saving technology. This paper is dedicated to study this new technology based on the field experiment at Shanghai Museum of Nature History. By the experiment, the heat transfer performance of heat exchanger in diaphragm wall and its impact factors including heat exchanger type, water velocity, inlet water temperature and operation mode were investigated. The test results show that (i) the heat exchange rate of W-shaped heat exchanger reached to 66.3 and 73.7W/m for tube type (a) and (b) at the inlet temperature of 35°C, which are approximately 1.2–1.4 times higher than that of single U-shaped type (c); (ii) under the experimental condition, the reasonable water velocity is 0.6–0.9m/s; (iii) the exchange rate reached to 40.3, 66.3 and 85.0W/m at the inlet temperature of 32, 35 and 38°C, respectively, for tube type (a), every 1°C rise of inlet water will promote 15% heat exchange rate; (iv) in intermittent operation mode, the average heat exchange rate is 82.8W/m while 72.7W/m for continuous mode under the experimental condition, i.e., 14.7% higher than that in continuous mode.