The article considers a method for optimizing circular ducts for ventilation and air conditioning systems. Universal dependencies are given to determine the diameters of the cross-sections of the air ducts and the air velocities in them that are technically and economically optimal. It is shown that the optimum air velocity in the section of the ventilation network does not depend on the site location relative to the fan of the system. Specific examples of determining the optimum diameters of air ducts and air velocities in them with the use of the dependences obtained are given in the technical and economic sense.

Keywords: Аir duct, aerodynamic calculation, ventilation system, air conditioning system, techno-economic optimization, optimal diameter, optimal air speed, energy saving, energy efficiency, aerodynamic efficiency

the paper presents characteristics of the solid waste landfill in the town of Novocherkassk, and the dynamics of pollutants’emissions from the landfill site for the period between 2015-2017 as well. The characteristic of the atmospheric air on the border with the nearby residential development and Novocherkassk landfill on the basis of the calculated air pollution index (API) and the complex index of atmospheric airpollution.

Keywords: landfill site, the contaminants, the maximum surface concentration, maximum permissible concentration, air quality

The work reflects estimates of measurements of the fractional composition and the concentration of wood dust at points located at different distances from the woodworking shop. In addition, the shape and adhesiveness of wood dust and its dusting ability are examined.

Keywords: Wood dust, concentration of wood dust, fractional composition, sanitary protection zone, mass distribution by diameters, slipability

The article is devoted to topical problems of modern construction - creating a comfortable environment for people in the premises and in the areas of construction by studying and researching the heat-wind processes in the city canyon. Particular attention should be paid to the role of insolation in the formation of the heat-wind regime of the canyon space, which is the determining factor of the thermal regime of the buildings and the building area.

Keywords: urban canyon, insolation, buildings, solar radiation, heat balance, radiation balance

Energy costs for grain drying are about 30% of the total energy consumption for grain produc-tion. Reducing the energy consumption of drying is possible due to the use of a microwave field. In this case, it is necessary to develop a design of a convection drying zone with a microwave field which will provide uniform drying of the grain throughout the volume. For this purpose, it is advis-able to carry out the simulation of the process. The developed computer model of heat and moisture exchange in the grain layer allows to model one under varying parameters of the grain layer and the drying agent. A computer model implements a stepwise calculation method. According to this method, the grain layer is represented as a series of computer models of the elementary layer. The grain layer is divided into three sections. The specific power of the microwave field is set to con-stant throughout each part. In addition, the model takes into account the features of changing in the specific power of the microwave field in the drying zone from the moisture content of the grain and the distance from the magnetron. The air flow in the microwave convection zone can has an im-portant value for the energy intensity of the process. The paper presents the results of modeling grain drying with two variants of air distribution in the microwave convection zone. Graphs of changes in grain moisture in each of the sections of the layer are given. It is shown that when the air moves from the magnetron, the time and the non-uniformity of drying decrease.

Keywords: drying of grain, grain layer, microwave field, microwave - convection drying, heat and - moisture exchange, computer model, modeling

The article discusses the methodology of assessing the technical condition of the regenerative air heater RVP-54 on power boilers Naberezhnye Chelny CHP on the basis of the results of the monitoring of the thermal efficiency. In article the algorithm of monitoring and evaluation of the thermal efficiency of regenerative air heater, allows in real time to compare actual performance with previous values and to eliminate the revealed violations.

Keywords: Naberezhnye Chelny CHP, energy boiler, regenerative air heater RVP-54, technical condition assessment, commissioning and configuration, thermal calculation, temperature difference, heating surface, thermal efficiency, heat losses

The paper considers the issue of the reduction of radon daughter products exhalation from construction materials into the indoor air of residential buildings. The characteristics of materials obtained through the use of radiation technologies are given.

Keywords: radon, exhalation, equivalent dose, volume activity, radon emanation, penetration, polymers, construction materials, gamma background, radon, radionuclides, alpha particles

The article presents a comparative analysis of dust pollution of atmospheric air of Volgograd and the city of Kabul. Given the dynamics of changes in the concentration of fine dust in the course of the year for these cities, and also investigated the characteristics of the concentration distribution

Keywords: air, fine dust, PM10, PM2,5, concentrations, meteorological parameters, normal distribution, logarithmic-normal distribution law

The article deals with Justification for the design of protective clothing against cold, the main means of calculation and design assessment which is mathematical modeling. Justification of pilot studies of influence of parameters of a matrix of fixing of the special soft polymeric edges forming the additional locally concentrated rigidity of external material of the warmed clothes of a special purpose is presented in article. Technical characteristics and standard restrictions for the textile material considered at the heart of the projected product taking into account the requirement of GOST and operational criteria are given. Data on modern ways of increase in resistance of an external cover of clothes to the deforming influences for the purpose of preservation of internal volume and, as a result, necessary thermal insulation of clothes are submitted. On the basis of established experimentally dependences of rigidity of the modified material on width and thickness of polymeric channels the way identification of extreme density of filling of polymers of the internal surface of integumentary material with it taking into account the requirement of hygienic and operational character is offered.

Keywords: heat-shielding clothes, design, modeling, physical-biological characteristics of a person, clothes in water, cooling of the person

The article is devoted to the problem of determining the air flow through cracks in the enclosing structures using numerical methods. Based on the study of the data obtained during the visual inspection, it was found that most of the apartment buildings have significant physical wear, which is mainly characterized by the presence of cracks. Particular attention is paid to the assumptions made for the design scheme. On the basis of the equations of dynamics and continuity, a mathematical model is obtained that allows one to predict the airflow through the crack

Keywords: physical wear, air mass flow rate, crack, permeation, water steam, heat and mass transfer, controlled environment, visual examination, air change, air permeance, numerical methods

With the aim of obtaining objective data about the energy potential of the air flow in the ventilation system proposed to use the parameter "local mechanical power flow". The formulas describing the change of this parameter in different parts of the ventilation system. Describes the author's method of graphic representation of the processes of change of flow parameters in the coordinate axes L - Pn, allowing enough just to determine the change in local mechanical power on isothermal and non-isothermal sections of the ventilation system.

Keywords: ventilation system, fan, mechanical power, heat exchanger, energy efficiency, energy conservation

The article presents the results of studies conducted by the national agency of Afghanistan on ecology and environmental protection and Russian authors of studies on the assessment of air pollution in the city of Kabul. An analysis was carried out for the formation of information on the state of air quality in the city of Kabul, when considering its street-road network as a source of chemical pollution of the air environment. A mathematical model of the dependence of the concentration of fine dust (PM10) on three factors: the speed of wind, humidity and temperature in the winter months of the city of Kabul.

Keywords: Air quality, dust, fine particles, moisture, wind speed, multiple regression coefficient, Fisher criterion

Drying module is a part of any modern gas analysing device. Using the Peltier elements for cooling the gas probe in druying module is a known technical solution. Peltier elements are very energy-intensive things. So the task of calculation of amount of electrical energy which is needed for predetermined temperature decline of gas probe is very topical. The solution of this task is given in the article. With formulas for partial pressure of vapour we can calculate the humidity of gas at the output of drying module. Then we can find the temperature of gas. Finally using the heat balance equation and nomogramms we can calculate the voltage for Peltier element.

Keywords: Peltier element, gas probe, drying process, gas analyzer, heat balance, partial pressure of vapour

The article is devoted to the calculation and assessment of background pollution of the atmosphere srednebalansovogo integral criterion for the studied regions of Volgograd for the years 2010-2013. Assessing the background air pollution, and creating a map of alternative sites for new industrial construction, is determined srednebalansovy integral criterion of pollution of the atmosphere of the study area. This requires calculation of the average concentration of harmful substances in each group summation of polluting the area. The data obtained were built integral and differential distribution function srednebalansovogo integral criterion of atmospheric pollution for Volgograd regions. According to the analysis the greatest volume of air pollution falls on Central and Traktorozavodskiy districts, which corresponds to the results of the calculations of the specific pollution load on the atmosphere of the city.

Keywords: biospheric compatibility, balance method, the biosphere, the technosphere, the atmosphere, the average balance integral criterion

In the article discusses the features of work air handling unit (AHU) based on spray chamber (SC), developed the design of the test bench and presents the results of the tests SC, identify ways to improve them, particularly in the lower part of the workspace was placed plane-parallel packing. It was established experimentally that the efficiency of processes of heat and moisture transfer increased by an average of 6 - 10%.

Keywords: air handling unit, spray chamber , heat and mass transfer, efficiency