To the determination of heating temperature of an object of thermal influence in solar power plants

The aim of the paper is to find the mathematical dependence of heating temperature of the object of thermal influence of solar power plant on its usage time under conditions of variable external factors. The object of thermal influence can be, for example, the wet grain meant for drying, the fresh air for natural ventilation systems of livestock houses, the water to heat up etc. The variable external factors are the weather conditions needed for right operating of solar power plant, in particular the solar activity throughout the day. The object of this research is the grain heating process in drum solar dryer. It is known that grain heating above a required temperature may reduce its viability. Therefore, in this case, forecasting of temperature for grain heating is of great importance for ensuring the quality of drying as a technological process. The time of effective use of solar energy in the drum solar dryer for grain heating process is about seven hours per day for conditions of the Bryansk region. In the basis of analysis of available experimental data, it is accepted that there is a directly proportional dependence between temperatures of the drying agent (the warmed-up atmospheric air) and grains during drying process. The differential equation of heat-transfer between grain and drying agent is solved using the methods of variable separation and substitutions. The dependence of the temperature of the object of thermal influence of solar power plant on its usage time under conditions of variable external factors is obtained. The analysis of the obtained exponential dependence shows that temperature of the object of thermal influence is generally defined by its reference temperature, weight and a thermal capacity, heating duration, heat-transfer coefficient.

heat-transfer equation, heating temperature, solar power plant, grain drying