REDUCTION OF HEAT GAINS TO GEOTHERMAL HEAT EXCHANGERS IN LONG-TERM OPERATION

Abstract

Link for citation: Polovnikov V.Yu., Shelemekhova S.D. Reduction of heat gains to geothermal heat exchangers in long-term operation. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 9, рр. 18-24. In Rus. The relevance of the research is caused by the colossal energy potential of geothermal and petrothermal energy. It is designed to stimulate research and development in the field of geothermal technologies. The development of technologies for the use of geothermal and petrothermal energy in the Russian Federation is reduced by some circumstances. These main reducing factors are competition from traditional energy, problems with the legal framework and the lack of relevant areas of research and development. Currently, there is a backlog of Russia in the field of development of geothermal resources from the world level. The main aim of the study is to evaluate the effect of condensation in the design of a geothermal heat exchanger on the change in heat inflows to it. The object of the research is a typical design of a geothermal heat exchanger consisting of a metal pipeline and a cement casing. Methods. Numerical analysis of heat and mass transfer was executed with rational values of the grid parameters and the time integration step. The assessment of the reliability of the results of the work was carried out by testing on the example of heat transfer problems, the numerical methods used and elements of the developed algorithms for solving boundary value problems of heat and mass transfer, checking the conservatism of difference schemes, and comparing with known data. The finite difference method and the implicit difference scheme were used. The peculiarity of problem solving was the discontinuity of the thermophysical characteristics at the contact boundaries between the layers and the presence of nonlinearity in the boundary condition. Results. The authors have carried out the numerical study of the effect of steam condensation in the design of a geothermal heat exchanger on the reduction of heat inflows in the system under consideration. It was found that steam condensation leads to a decrease in heat gain by 4,55–31,19 %. It is shown that the use of relatively simple heat transfer models makes it possible to predict the change in heat inflows to a geothermal heat exchanger under conditions of steam condensation in its structure during long-term operation.