The article considers the problem of sediment formation, sludge and corrosion on the heat transfer surface during the operation of heat exchange equipment at housing and communal services facilities. A new method of non-selective mechanical cleaning using a water hammer is proposed. The description and principle of operation of this cleaning system at the central heating station of the Ogarev Moscow State University are given. To confirm the effectiveness of the proposed technical solution, the results of thermal and hydraulic tests are presented.

Keywords: deposits, sludge, corrosion, cleaning, heat exchanger, water hammer, heat transfer

The use of closed methods for laying underground polyethylene gas pipelines using horizontal directional and directional drilling methods when crossing artificial and natural obstacles is considered. The results of calculating the geometric parameters of the working and receiving pits when laying polyethylene gas pipelines using a closed method using horizontal directional drilling are presented.

Keywords: polyethylene gas pipeline, closed installation method, horizontal directional drilling, directional drilling, dimensions of working and receiving pits

The article is devoted to modeling heating of fuel oil using a pulsed fluid flow in the SolidWorks Flow Simulation software module. In the future, the use of this technological solution can be considered by a number of industries in the Russian Federation and abroad. The purpose of this article is to describe the results of a computer model of the technological process under study. The computer calculation of the fuel oil heating model using a pulse flow makes it possible to evaluate the efficiency of the process and determine the optimal parameters to achieve maximum efficiency. This will help to reduce the cost of heating fuel oil and increase the efficiency of industrial equipment of enterprises.

Keywords: fuel oil, oil, coolant, shock unit, diaphragm pump, pulse flow, turbulent mode, cavitation, solidworks flow simulation

When choosing an intensification method, the assessment of thermal-hydraulic efficiency is an important criterion. In this paper, the thermal-hydraulic efficiency of the pulsating method of heat transfer intensification was assessed as applied to an in-line tube bundle. The thermohydraulic efficiency was estimated by comparing the ratio of the increase in the Nusselt number to the increase in the coefficient of friction factor in a pulsating flow compared to a stationary flow. The coefficient of friction factor was determined by numerical simulation in AnsysFluent. The results of a numerical study showed that an increase in the product of the pulsation amplitude and the Strouhal number leads to a decrease in the thermal-hydraulic efficiency at all values of the Reynolds number, while the thermal-hydraulic efficiency is higher at the minimum values of the Reynolds number.

Keywords: Reynolds analogy factor, flow pulsation, heat transfer enhancement, thermal hydraulic efficiency.

In connection with improvement of public welfare, coming to the fore are requirements enabling comfortable living, which primarily depends on conditions of indoor air environment. This article provides arguments to suggest that, during reconstruction and overhaul of residential buildings, natural ventilation systems, failing to provide the required air exchange, need to be replaced with hybrid ventilation systems, allowing to maintain stable ventilation in existing multi-storey buildings throughout the year and involving minor capital and operating costs. Based on the example of a typical nine-storey residential building, two variations of hybrid ventilation have been developed: containing an ejector and roof fans, with economic feasibility of using both determined.

Keywords: microclimate quality, air exchange, natural ventilation, hybrid ventilation, an ejector, a roof fan, economic feasibility

The possibility and expediency of switching from qualitative regulation of heat supply to quantitative in centralized heat supply systems for the existing network from the district boiler house No. 1364 of Volgograd is substantiated. The main advantages and disadvantages of each method of regulating heat supply to consumers are considered. The basic formulas for determining the thermal loads required depending on the outside air temperature, the hydraulic calibration calculation of the existing network from boiler house No. 1364 are described. Volgograd, determination of the internal hydraulic characteristics of the resistance of the heat network and determination of the required hydraulic regime for consumers of the microdistrict No. 1364, depending on the change in coolant flow due to the regulation of the speed of rotation of the pump impeller. As a result, the implementation of the transition from a qualitative to a quantitative method of regulating heat release is possible without serious hydraulic interventions.

Keywords: heat supply, control methods, heat carrier temperature, heat carrier consumption, boiler room, heat network, pump, frequency-controlled drive, hydraulic modes, thermal energy saving

The results of research of engineering solutions for ventilation of swimming pools based on mathematical modeling taking into account real thermal loads and moisture releases are presented. The analysis of air distribution options in rooms with swimming pools for various purposes – a public swimming pool, a SPA complex and a sports pool with bleachers for spectators. Based on the results obtained in the form of distribution fields of the parameters of the air environment, the necessary changes in the schemes of the organization of air exchange are revealed. If the parameters deviate from the normalized values, recommendations have been developed to improve the state of the microclimate. These temperature distributions allow us to conclude that the air temperature near the surfaces of external fences meets the requirements that ensure their safety. conclusions on the compliance of the obtained results with the required parameters of the microclimate for rooms with high relative humidity.

Keywords: Swimming pool, ventilation, heat, moisture, air distribution, microclimate, air environment, numerical modeling

The article discusses the main causes of natural gas leaks and ways to detect them. Data on the volume of natural gas leakage and the nature of damage were obtained at the experimental installation. The objects of experimental research are gas connections to devices, such as: bellows hose made of stainless steel, rubber hose and cap nut of gas connection with varying degrees of tightening. The course of conducting an experimental study of filling a room with natural gas, depending on the degree of damage to the gas supply and its nature, is described. The analysis of the results of the experiment to determine the dependence of the gas flow rate on the type of damage to the gas supply is carried out. The most dangerous types of leaks in the room are determined, graphs of the dependence of gas flow through various damages and methods of their prevention to prevent such situations are constructed.

Keywords: gas leak, gas appliances, leak detection, types of gas leaks, type of damage to the gas supply

The value of the efficiency of domestic gas boilers of the brand Baxi ECO-4S 24 with various schemes of air supply and smoke removal is considered. The difference in the calculated efficiency values and the passport values is analyzed.

Keywords: efficiency, flue gas discharge, household gas boiler, thermal balance, energy efficiency

The tasks of preparing for the modernization of the automatic pressure control system with the transition from the use of a PD controller in favor of a PID controller and the introduction of a controlled electric fan drive in a boiler plant are being solved. A technique for constructing a fan model in the automatic control system for air supply to the boiler is given using the example of a VD-18 blower fan and a BKZ-160 boiler. The block diagram of the operation of the fan and pipeline is given. A mathematical model of the fan is shown, a calculation is made and a computer model is designed in MATLAB Simulink. The simulation results are presented, which prove the correctness of the obtained model. The presented model can serve as a basis for automating the air supply system in other boilers using blowers.

Keywords: automatic pressure control system, automatic control system, dynamic model, computer model, blower fan, boiler plant

The article substantiates the need to clarify the value of pressure losses in the shut-off valves. Various methods of determining the coefficient of local resistance of steel ball valves are considered. A comparative analysis of the values of the local resistance coefficient obtained theoretically and experimentally is performed. Recommendations on the application of numerical values of the local resistance coefficient of steel ball valves are given.

Keywords: hydraulic calculation, pressure loss, disconnecting devices, ball valve, local resistance coefficient

The work of new Russian regulators RED is being considered. The results of a study of the compliance of regulators with the declared class of locking pressure using the "PLEXOR" installation are presented. The conducted tests show that Russian gas pressure regulators in the conditions of import substitution are not inferior to foreign analogues in their technical and functional characteristics.

Keywords: gas reduction point, pressure regulator, locking pressure class, diagnostics, setting limits

The issues of seasonal unevenness of gas consumption for the needs of heating, ventilation and hot water supply of the shopping and leisure complex are considered. Calculations of volumetric and power indicators of uneven gas consumption for 2020-2022 are given according to the data of the archive of gas consumption meters.

Keywords: gas consumption, uneven gas consumption, volume, capacity indicators, shopping center

The work of the FL200AN300+TR regulators installed in the hydraulic fracturing plant No. 4 in Volgograd is considered. The results of calculations of the throughput capacity of pressure regulators are presented. The range of their stable operation is determined on the basis of archival data of the gas flow metering unit. It was revealed that not all outlets provide stable operation of pressure regulators with minimal gas consumption.

Keywords: head gas control point, pressure regulator, throughput, range of stable operation