The reliability of the solar heating system with solar collectors was studied using the logical-probabilistic method by building a fault tree. The fault tree was obtained by sequentially detailing the events associated with failures of the solar heating system, as well as its elements. Events were taken into account: conducting test diagnostics of elements of the power supply system, repairing failed elements, failure of elements, reducing the power of solar collectors due to a decrease in the intensity of the solar radiation. The events were divided into two groups: events in which there is sufficient intensity of solar radiation for the hot water supply from the solar collectors, as well as events when the heating supply cannot be provided only due to the solar collectors. The last group of events was divided into two subgroups, within events caused short-term downtimes (at the time of switching) and long-term downtimes (at the time of replacing or repairing a failed system element). Long shutdowns are associated with the coincidence of failures, repair or diagnosis of one or more elements of the solar heating system. Expressions are compiled to calculate the probability of long downtimes, the probability of short downtimes, the probability of failure due to a decrease in the intensity of the solar radiation, and the total probability of failures. As a result of substituting the values of the reliability indicators of the elements of the solar heating system, the value of the total probability of failure during the year is 4.03∙10-5.

Keywords: solar hot water supply, reliability, solar collector, failure cause, reliability modeling

The results of a numerical experiment that obtained with using of the developed mathematical model of the operation of the power supply system of the greenhouse are presented. The list of input factors of the model included external factors: ambient temperature, length of daylight hours, wind speed, insolation, and factors that characterize the internal working conditions of the greenhouse.The values of external factors varied within the average daily values for the location of the greenhouse, the process parameters were determined taking into account the possible modes of operation of the greenhouse. The dependences between the amount of thermal energy consumed by the greenhouse, the energy consumption of the energy supply system, the gross energy consumption of the energy supply system, the utilization rate of gross energy and the levels of factors are shown. The results of the analysis of the obtained dependencies are presented.

Keywords: modeling, power supply system, greenhouse

A dynamic model of the process of internal corrosion of pipelines of heating networks is considered. Model include five level: the level of the wall thickness of the pipeline, the level of slowing down of thinning of the wall of the pipeline from pH, the level of accelerating of thinning of the wall of the pipeline from temperature, the level of accelerating of thinning of the wall of the pipeline from the oxygen concentration, the level of slowing down of thinning of the wall the pipeline from the carbonate index. The composition of variables includes one level of state, thar characterize the process of thinning the wall of the pipeline due to internal corrosion, and four levels, that characterize the performance of network water. Six rates of changing of the physical indicators, that characterize the growth (dynamics) of the ongoing process, are taken into account. Four dependencies of influence are connect the subsystems of the complex into a single whole. The results of the evaluation of the dynamics of the pipe wall thinning process in the process of internal corrosion for a period of 1 year and 5 years presented. The software implementation in the Mathcad environment is considered.

Keywords: dynamic model, internal corrosion of pipelines, corrosion of the heat network, corrosion factor

Optimization of technical parameters of the complex for climate control beehives allowed to choose the optimal ratio of the technical parameters of the equipment in accordance with the optimization objective. Evaluation of the efficiency of the self-contained complex is considered in two aspects: in relation to conversion and transmission of energy and in relation to the specific consumption of material resources. In this regard, was chosen two criteria characterizing the efficiency of the complex - the energy efficiency and material capacity. In article presents a methodology to optimize constructive parameters of the energy supply system based on the combined solar plant. The resulting optimal ratio of the parameters are the basis for the engineer's decision that design complex for climate control beehives.

Keywords: optimization, efficiency, system power supply, renewable energy