Numerical analysis of the equipment position influence on the premises thermal regime under gas infrared emitter operation and mixed convection conditions

The analysis of mathematical modeling results on premise heating by a gas infrared emitter (GIE) during supply and exhaust ventilation operation is presented in this article. The model is presented in a one-dimensional non-stationary setting for an incompressible medium with allowances for the radiant heat flux transfer between opaque solid surfaces in the air. The air is transparent to thermal radiation. The traditional k-ε model is used for turbulence modeling. The possibility for creating comfortable conditions in the area of a horizontal surface with different heights, imitating laboratory equipment, is analyzed.

Temperature regime of painted parts in awning-type drying chambers at low ambient temperatures

The paper considers the problem of colouring large-sized objects, such as modules of sea and river vessels at low ambient temperatures. The temperature distribution depends on the thermal resistance of the walls of the drying chamber, the main characteristics of the heater fan, the dimensions of the chamber and the painted module, the gaps between the walls. The calculation should take into account the aerodynamic resistance of the drying chamber with the part placed in it, the influence of free convection, heat loss and the peculiarities of air distribution inside the shelter. The paper presents the results of a study of the influence of the size of the drying chamber, the size of the painted module, ambient temperatures and air coming from the heater, fan parameters, methods of placing the fan and exhaust ventilation on the range of air temperature changes in the tent. The methods of numerical modelling and experimental studies were used in the study. Based on the results obtained, a calculation method is proposed that allows determining the decrease in temperature inside the chamber relative to the temperature of the air coming from the heater. To automate the calculations, a program has been developed to determine the parameters of the air after heating with a fan heater.

Ecological houses as an area of energy efficient and green construction

The relevance of the construction of ecological houses (eco-houses), i.e. houses made from environmentally friendly building materials, is increasing due to the exacerbation of environmental problems on a global, regional and local scale. The purpose of this study is considered to be the actualization of the concept of ecological houses in relation to modern conditions, taking into account new and future requirements for buildings. Ecological houses are considered as a kind of modern green buildings. Particular attention is paid to energy efficiency as an essential requirement for new buildings. Eco-friendly building materials have two qualities at the same time: they are more favorable to humans; their use has a minimal impact on the environment, taking into account the entire life cycle of the building material. As a rule, natural materials (materials of natural origin) are considered environmentally friendly. It is rationally to apply the experience of energy efficient and green construction for environmentally friendly buildings: compact architectural forms, translucent structures with the effect of passive solar heating, supply and exhaust ventilation with heat recovery, automation of engineering systems, elimination of heat bridges (cold bridges).

Benzene Exposure on Rig X from Drilling Fluid and Effectiveness of Local Exhaust Ventilation

Introduction: Benzene is a carcinogenic compound commonly found in drilling fluid, a chemical used in oil and gas drilling operations. Benzene exposure to workers is known to cause acute and/or chronic disease. Adequate control measures shall be identified and implemented to prevent the adverse health effects of benzene from the utilization of drilling fluid. Methods: This study measured benzene concentrations at several locations, above the drilling rig, which has the potential risk of benzene vapor exposure. From the measurement results, if the threshold limit value was exceeded, LEV was proposed to be installed and the effectiveness of LEV at each location would be assessed. A two-tailed t-test was used with a confidence level of 95% (α=0.05) to measure the effectiveness of LEV. Results: In several areas, benzene concentration exceeded TLV-TWA, and LEV was installed in those areas as control measures. In this study, it was found that LEV was not always effective in reducing the concentration of benzene in some areas. Conclusion: Drilling fluid was essential for drilling activity, and this could cause benzene vapor to contaminate the working area. The installation of the LEV shall consider the type of containment through which the drilling fluid flows to ensure the mitigation measures are effective to reduce the concentration of benzene in the air that may be exposed to workers.Keywords: benzene, drilling fluid, exhaust ventilation

Local Exhaust Ventilation to Control Dental Aerosols and Droplets

Dental procedures produce aerosols that may remain suspended and travel significant distances from the source. Dental aerosols and droplets contain oral microbes, and there is potential for infectious disease transmission and major disruption to dental services during infectious disease outbreaks. One method to control hazardous aerosols often used in industry is local exhaust ventilation (LEV). The aim of this study was to investigate the effect of LEV on aerosols and droplets produced during dental procedures. Experiments were conducted on dental mannequins in an 825.4-m3 open-plan clinic and a 49.3-m3 single surgery. Ten-minute crown preparations were performed with an air-turbine handpiece in the open-plan clinic and 10-min full-mouth ultrasonic scaling in the single surgery. Fluorescein was added to instrument irrigation reservoirs as a tracer. In both settings, optical particle counters (OPCs) were used to measure aerosol particles between 0.3 and 10.0 µm, and liquid cyclone air samplers were used to capture aerosolized fluorescein tracer. In addition, in the open-plan setting, fluorescein tracer was captured by passive settling onto filter papers in the environment. Tracer was quantified fluorometrically. An LEV device with high-efficiency particulate air filtration and a flow rate of 5,000 L/min was used. LEV reduced aerosol production from the air-turbine handpiece by 90% within 0.5 m, and this was 99% for the ultrasonic scaler. OPC particle counts were substantially reduced for both procedures and air-turbine settled droplet detection reduced by 95% within 0.5 m. The effect of LEV was substantially greater than suction alone for the air-turbine and was similar to the effect of suction for the ultrasonic scaler. LEV reduces aerosol and droplet contamination from dental procedures by at least 90% in the breathing zone of the operator, and it is therefore a valuable tool to reduce the dispersion of dental aerosols.

Thermal regime of the local working zone in the industrial premises under radiant heating conditions

The results of experimental studies on recording temperatures and heat fluxes for the local working zone in industrial premises under radiant heating conditions and supply and exhaust ventilation operation are presented. The characteristics are measured on the surface of the horizontal remote panel directly under the radiator and along the wall with the ventilation inlet. Experimental results show that mixed convection caused by the operation of air exchange systems leads to mixing of air masses and more intensive cooling of the horizontal panel surface, as well as air, compared to the natural convection regime.

Heat transfer under conditions of operation of a gas infrared emitter and an air exchange system

In this work, the processes of heat transfer in a premise heated by a gas infrared emitter (GIE) are studied on the basis of numerical solution of the heat and mass transfer equations in a two-dimensional formulation. Calculations are carried out taking into account the presence of supply and exhaust ventilation in the considered area. Ventilation is required during the operation of high-intensity type GIE. The analysis of the main heat and mass transfer parameters by radiant and convective flows is carried out.

Study of Cold Air Treatment in a Poultry House in the Conditions of Azerbaijan

Broiler farming at industrial poultry enterprises is carried out in conditions of intensive technology. One of the most important technological aspects is the creation and maintenance of regulatory parameters of the microclimate in the production room, that is, comfortable conditions for poultry at the level of livestock placement. Ensuring an optimal microclimate is achieved through a complex of supply and exhaust ventilation equipment and auxiliary systems. It is important to determine the level of influence of the microclimate in the formation of viability and productivity of broilers in the industrial cultivation technologies; features of the formation of microclimatic zonality in poultry houses, which indirectly determines the uniformity of the poultry herd, and to outline ways to improve the microclimate. The use of water evaporators in the field of cold air treatment has shown that structures with freely assembled material cannot simultaneously fully, evenly and efficiently copy the treated air. All this creates the need for mathematical modeling of the process of mass transfer of heat going in the channels of evaporation tubes provided for by the improved scheme.

Evaluation of One- and Two-Box Models as Particle Exposure Prediction Tools at Industrial Scale

One- and two-box models have been pointed out as useful tools for modelling indoor particle exposure. However, model performance still needs further testing if they are to be implemented as trustworthy tools for exposure assessment. The objective of this work is to evaluate the performance, applicability and reproducibility of one- and two-box models on real-world industrial scenarios. A study on filling of seven materials in three filling lines with different levels of energy and mitigation strategies was used. Inhalable and respirable mass concentrations were calculated with one- and two-box models. The continuous drop and rotating drum methods were used for emission rate calculation, and ranges from a one-at-a-time methodology were applied for local exhaust ventilation efficiency and inter-zonal air flows. When using both dustiness methods, large differences were observed for modelled inhalable concentrations but not for respirable, which showed the importance to study the linkage between dustiness and processes. Higher model accuracy (ratio modelled vs. measured concentrations 0.5–5) was obtained for the two- (87%) than the one-box model (53%). Large effects on modelled concentrations were seen when local exhausts ventilation and inter-zonal variations where parametrized in the models. However, a certain degree of variation (10–20%) seems acceptable, as similar conclusions are reached.