The background of this article is the potential energy savings of solar heat supply systems due to the use of the renewable energy of solar radiation. The motivation is to create a solar collector design that would combine the functions of both a building cover and a solar collector. It is necessary to investigate and compare different types of solar collector coatings (traditional and modern) and pipe diameters. The purpose of the article is to solve aspects of energy efficiency for new eco-friendly solar collectors. The most effective result occurred with the solar collector covered with the rubber–graphite composition of Grafplast PDA, and when using Prandelli/Tuborama pipes with a diameter of 0.016 m. Their efficiency increased by 8% compared to the second version of the collector made using a more traditional solution. The influence of the distance between the pipes and the flow rate of the heat carrier on the efficiency of the solar collectors was evaluated.

The article is devoted to decision of actual task of air distribution efficiency increase due to swirled air jets application. The aim of the paper is investigation of swirled air jets, analytical dependencies obtaining for determination of the air velocity attenuation coefficient, aerodynamic local resistance coefficient and noise level from the twisting plates inclination angle; optimization of the twisting plates inclination angle of the air distributor. It has been established that increase of the angle results in the air velocity attenuation coefficient increase and results in decrease of the noise level and resistance coefficient of air distributor. The optimum angle of the plates is determined considering aerodynamic, noise and energy aspects and equals 36°.

Purpose. To increase the energy and economic efficiency of heating coal mines with infrared heaters through energy saving measures, taking into account the dynamics of the discount rate. To achieve this goal, the task was to conduct an energy audit of the heating system of the mine during its reconstruction according to an improved method, taking into account the dynamics of the discount rate and measures that are not feasible at the same time. Methodology. When using infrared heating systems, local heating of the working area is provided. As a result, the necessary temperature conditions in the mines are maintained and there is a possibility of creating a local microclimate. A multifactorial experiment was performed and the research results were graphically and analytically described. Furthermore, the method of energy audit, taking into account the effect of complex interaction of factors and the dynamics of the degree of discount, is applied. Findings. According to the results of the experiment, a nomogram of the temperature regime of the irradiation area with an infrared heater was constructed, which was approximated by the analytical dependence. The optimal profit from the introduction of energy-saving technologies during operation is EUR 379.2 under the following conditions: replacement of the heating system from stationary to variable with automation; installation of a different number of infrared heaters NL-12R with power Q 1200 W each; application of the effect of complex interaction of factors. Originality. The conducted energy audit of the radiant heating system with the use of infrared heaters during the underground reconstruction showed that non-stationary heating is efficient because it saves energy and has the lowest payback period. Practical value. The expediency of using infrared heaters in variable mode in both energy and technical and economic aspects has been proved. These measures will provide comfortable conditions in the mine and have a significant economic effect.