دانلود رایگان مقاله انگلیسی فن آوری ها و اثرات زیست محیطی مبدل های حرارتی زمین در فنلاند - الزویر 2018

ABSTRACT

Finland is one of the northernmost countries utilizing ground source heat pumps (GSHPs). In this north European country, GSHPs’ operating conditions are characterized by the cold climate, and hard, crystalline bedrock. Environmental risks and technical problems with ground heat exchangers (GHEs) have been much discussed, but the frequency of complications has not been previously studied in Finland. This article examines the types and construction practices of GHEs, and the range of problems in GHEs experienced by the practitioners. The data was collected through a questionnaire study among Finnish GSHP practitioners, and thematic interviews of Finnish heat pump experts. Borehole heat exchangers (BHEs) proved to be the most popular GHE type in Finland with a share of 85%. The questionnaire responses indicate that the most common complications in BHEs are connected to collapsed boreholes, and artesian or otherwise abundant water yields. Also, issues relating to heat transfer fluids, drilling through multiple aquifers, and design errors are discussed.

4. Conclusions and recommendations

This study has investigated the types and construction practices of GHEs in Finland, a north European country, and the kinds of problems GSHP practitioners have encountered in their GHE projects. BHEs were found to be the most common GHE type with a proportion of 85%. The most frequent complications in BHEs are collapsed boreholes, and artesian or otherwise abundant water yields. Hazardous heat transfer fluids (mainly methanol), and removing them from the market, have been topical in Finland. Another threat for the ground water is drilling through multiple aquifers, and neglecting proper sealing to prevent surface water from entering the borehole.

Sufficient regulations, applicable to the Finnish conditions, are needed to ensure that environmental conservation and functionality are duly considered in the design and construction of GHEs. Such regulations include adequate qualification requirements and mandatory training programs for drillers, installers and designers, and binding criteria for GHE and borehole construction. In the construction criteria, the use of for example surface water sealing and manholes in borehole construction should be considered. Bleicher and Gross (2016) have argued that, due to the unpredictability of the hydrogeological conditions, the construction of each GSHP system may be viewed as a real world experiment. These experiments produce valuable knowledge on problems and solutions, which should be collected and shared systematically to promote the development of the industry and the administrative practices. To accomplish this, openness from the practitioners’ side is needed in sharing their experiences.