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This paper contains the results of research, carried out with financial support from the Ministry of Education and Science of the Russian Federation (contract ID RFMEFI57914X0026). For the ground source heat pump (GSHP) used as a heating system in regions with cold climate the thermal effects of ground moisture freezing-melting processes can make an essential long-term impact on GSHP performance. However, widely known models of heat transfer inside and outside GSHP borehole do not take into account such effects. In this paper we propose a method of engineering estimation of freezing-melting latent heat in the frame of modified cylindrical source model. The key feature of the method is the definition of effective thermal conductivity of ground to "convert" the latent heat of phase transition into equivalent heat flux from outer ground. The method is validated by laboratory measurements of ground thermal conductivity during the freezing-melting process.

This paper contains the results of research, carried out with financial support from the Ministry of Education and Science of the Russian Federation (contract ID RFMEFI57914X0026). For the ground source heat pump (GSHP) used as a heating system in regions with cold climate the thermal effects of ground moisture freezing-melting processes can make an essential long-term impact on GSHP performance. However, widely known models of heat transfer inside and outside GSHP borehole do not take into account such effects. In this paper, we propose a method of engineering estimation of freezing-melting latent heat in the frame of modified cylindrical source model. The key feature of the method is the definition of effective thermal conductivity of ground to "convert" the latent heat of phase transition into equivalent heat flux from outer ground. The method is validated by laboratory measurements of ground thermal conductivity during the freezing-melting process.

The article shows results of studies on assessing the effectiveness of new principles for heat recovery of exhaust air in ventilation systems of apartment buildings (AB). Technological solutions are known that provide heat recovery of the exhaust air for heating the supply air of ventilation systems. The efficiency of such solutions can reach 90%, but only in the coldest five-day period of the year with the maximum temperature difference between the exhaust and supply air. At all other times of the heating season, the efficiency of the recuperative heat exchangers decreases as the outside air temperature rises. In the studies presented in the article, a technology was considered that was free from this drawback. It is based on a two-stage heat recovery of the exhaust air: first, recovery for heating the supply air, and then “additional recovery” using heat pumps for the needs of AB hot water supply. The article shows results of assessing the effectiveness of the proposed two-stage heat recovery of exhaust air in various regions of the Russian Federation.

Authors of this article presents the results of experimental research of the temperature potential of ventilation emissions in apartment buildings in Moscow. Also this paper offers an analysis and synthesis of technological schemes and technical solutions for natural ventilation systems used in apartment buildings. The systems of natural ventilation of lower-cost multi-storey buildings have been analyzed. The influence of various factors on the parameters of operating modes of natural ventilation systems have been also analyzed. As a result of the analyses it has been found, that the operated apartment buildings largely do not ensure air exchange required according to sanitary regulations, which results in adverse effects for the health, efficiency and life expectancy of population.