In this paper, the method of determining the level of heat losses through structures of a cylindrical tank for backup fuel of boiler rooms and steady-state non-uniform temperature distribution in a multilayer tank have been considered, given that the heat transfer coefficient depends on r and z coordinates.

The article presents the findings of the tests conducted for the forced air heating unit of a supply ventilation system. The supply air system is designed to feed clean air into the industrial facility of the oil-gas field of the Yamalo-Nenets Autonomous District. The tests were performed in five modes at the ambient air temperatures of -5, -10, -15, -20, -25 °C. The mode throughout the tests was steady, i.e. the temperatures of water and air remained unchanged within 30 minutes before the tests. Since the capacity of the heater unit was proved to be 24 - 41.5% according to the test results, recommendations were made to improve the capacity. With the said measures having been taken, control measurements of test parameters were carried out, the actual U-value was calculated and the capacity of the heater unit was determined. The performed work is relevant in view of theoretical and practical significance for engineers and employees of industrial enterprises servicing the ventilation systems.

The energy efficiency of the heater depends on the U-value at certain energy costs. The article considers the calculation method for the heater performance efficiency in the inlet ventilation and air curtain of the garages for 100 and 75 motor vehicles of the largest industrial enterprise rendering transport services in transportation of loose cargoes, including ores and metal-containing products, large-sized and heavy cargoes, hazardous cargoes etc. The ventilation systems of the surveyed garages are combined with air heating. In order to determine the efficiency of the air handling units, the heat carrier flow through the heater, heat carrier temperature and the air temperature at the inlet and outlet of the air heater, the flow of heated air and the phase currents through the fan motor have been measured. Basing on the instrumental measurements carried out, the calculation results for the air heater thermal performance and the air consumption have been presented, and the determination method for the real U-value and the thermal efficiency of the examined heaters has been provided. Recommendations have also been made to improve their performance. This method is an important hands-on recommendation for the engineers serving air handling units and for the departments developing energy-saving activities for industrial enterprises.

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The method of determining the level of heat losses through structures of heat networks and the two-dimensional steady-state heat conduction problem for multilayer structures of heat networks have been considered, given that each of the layers has its own physical properties and heat transfer coefficients depend on r and z coordinates. The definition of heat losses is an important practical task, since they are one of the main indicators of energy efficiency in the operating heat networks and are included in heat tariffs.