Thermal Engineering Calculations Research Articles

Climate system design methodology for a new family of unified combine harvesters

BACKGROUND: Designing a combine harvester cabin climate system is a complex and multi-stage process that includes solving a set of tasks. To solve the tasks set, a design engineer must have knowledge and skills in various fields, starting with thermal engineering calculations and ending with experimental research methods and computer modeling, which requires a large amount of intellectual and time resources. Therefore, the task of creating a unified combine harvester cabin climate system design methodology is very relevant. AIMS: The purpose of this work is the calculation and design of a climate system for a unified cabin of a grain harvester and a forage harvester. The designed climate system is designed to create a comfortable microclimate in the cabin of the combine for 2 people in summer and winter operating conditions. METHODS: The methodology of development of combine harvester cabin climate system is considered, which includes the development of engineering calculation methods and mathematical modeling of thermodynamic and ventilation processes in the cabin. RESULTS: The main parameters were determined: heat intakes and heat losses for the grain harvester and forage harvester cabins, which amounted to 2.8 and 2.2 kW for the grain harvester; 2.9 and 2.35 kW for the forage harvester; the required air flow rate supplied to the cabin to ensure a comfortable temperature – 740 m3/h; the percentage of air recirculation from the conditions of absence of fogging and creation of overpressure in the cabin – 75 %; the cooling and heating capacity of the climate system, taking into account the operating conditions of the combine, is 7.8 and 6.3 kW, respectively. The selection of the main equipment of the climate system for a unified cabin for a new family of unified cabins of combines – evaporator-heater BUHLER 1000 MFWD; compressor Valeo TM16. CONCLUSIONS: Designed in accordance with the presented climate system methodology, it will ensure a comfortable cabin air temperature in the range of 22-24 °C under various operating modes of the combine in different regions. In addition, the climate system parameters will eliminate fogging of the cabin windows and, due to the created overpressure, the penetration of dusty air inside.

Estimation of the Reduction Coefficient When Calculating the Seismic Resistance of a Reinforced Concrete Frame Building after a Fire

The consequences of destructive earthquakes show that the problem of analyzing the response of reinforced concrete frames under seismic loads after a fire is relevant. The calculation models used for individual elements and buildings as a whole must take into account the nonlinear properties of concrete and reinforcement. In the spectral calculation method, the nonlinear properties of materials are taken into account by introducing a reduction coefficient to the elastic spectrum. When determining the reduction coefficient, a common deformation criterion is based on the use of the plasticity coefficient. The seismic resistance of a three-span, five-story reinforced concrete frame under four different fire exposure options is considered. The residual strength and stiffness of frame elements after a fire is assessed by performing a thermal engineering calculation in the SOLIDWORKS software for a standard fire. For the central sections of the elements, the highest temperatures were obtained after heating—during the cooling stage. The reduction coefficient is estimated by performing a nonlinear static analysis of reinforced concrete frames in OpenSees and constructing load-bearing capacity curves. Fracture patterns and damage levels in plastic hinges are analyzed. Based on the numerical modeling of reinforced concrete frames after exposure to fire, it was revealed that the most dangerous scenario is the occurrence of a fire on the first floor of the building. Based on the obtained plasticity coefficients, reduction coefficients were determined in the range of 2.62 to 2.44. The influence of fire on the permissible damage coefficient of a reinforced concrete frame is assessed using the coefficient φK—the coefficient of additional damage after a fire, which is equal to the ratio of the reduction coefficients for the control and fire-damaged frames. Depending on the percentage of damaged structures on the first floor, the following values were obtained: 50% or less—φK = 1.09; 100%—φK = 1.17. The obtained coefficients are recommended to be used when assessing the seismic resistance of a reinforced concrete frame after a local fire.

Математическое моделирование термодинамических процессов в вентиляционных шахтах метрополитена

Objective: To develop recommendations for performing thermal engineering calculations during the ventilation shafts renovation with the creation of internal thermal insulation made of foam glass concrete. Methods: Mathematical modeling by the Metrogiprotrans method of the shaft lining in an elastic medium for specified movements from expanding ice; mathematical modeling by the finite elements method of a system including a ground massive, shaft lining and a load from convection (cold air flow). Results: The criteria for the risk of the ventilation shafts lining destruction during freezing of water-saturated soil behind the lining have been established. It has been established that the destruction of cast-iron lining from the ice expansion depends on the amount of soil resistance and the size of voids behind the lining, but not on the depth of the location of the section under consideration. An influence assessment of the soil thermodynamic characteristics during the ventilation shafts operation in conditions of alternating temperatures has been performed. It was found that as a result of a very wide change in the thermal characteristics of the medium, the temperature behind the lining during thermodynamic calculations changes insignificantly — within 1 °C, and the thermal characteristics of the foam glass concrete layer play a decisive role in heat distribution. Practical importance: The results of the study can be used during the inspection of subway ventilation shafts, as well as an algorithm for conducting thermodynamic calculations for projecting shafts renovation with an insulation made of foam glass concrete.

Assignment of initial parameters and boundary conditions for modeling thermal state of underground pipelines in a zone of progression of island permafrost soils

Relevance. Determined by the importance of predictive modeling of thermal state of pipeline transport facilities located in the permafrost zone. Prediction of geocryological effects is possible through computer simulation of heat and mechanical interactions between a pipeline and a soil medium. Such simulators use data on climatic and geocryological conditions and processes, as well as the information about design and process-dependent parameters of the pipeline, data on its spatial positioning. The presence of various factors influencing heat and mass transfer, as well as the complexity of their numerical simulation, can lead to incorrect design decisions. Such decisions in their turn are always associated with a loss of mechanical safety in an underground pipeline operation. To eliminate this design problem, it is necessary to correctly take into account and adopt the most relevant methods for modeling processes and soil characteristics. Aim. To conduct an analytical comparison of the results of thermal engineering calculations of one section of the route with insular permafrost in order to identify the influence of the model initial parameters on the stress-strain state of the pipeline. Methods. Analyzing the results of engineering surveys for the object of study, conducting a number of numerical calculations, and factorial comparison of the calculation results. Results. At the first stage, the authors have selected the route section of the underground pipeline corresponding to the purpose of the research, the factors influencing the results of thermal modeling. These factors will be considered in this study. At the second stage, the authors carried out modeling of 30 calculation models of one route section with a different set of input data. A factorial comparison of the effect of heat engineering calculation on the results was carried out. At the last stage, the authors carried out the strength calculations of all options for the selected section of the pipeline route as a resulting indicator of the influence of factors.

Frost soil interaction with the cement-sand mortar of a driven precast pile

Introduction. The drilling method of pile driving represents the most common method of constructing foundations on permafrost soils. In order to reduce the tangential forces of frost heaving, the space between the pile surface and a leader well wall within the layer of seasonal freezing-thawing is filled with non-heaving sandy soil. This technology complicates the process of installing driven precast piles. In this case, a significant simplification involves filling the space between the pile and the soil with a cement-sand mortar (CSM) along the entire height of the pile. However, at present, no method is valid for calculating driven precast piles for the action of frost heaving tangential forces during CSM freezing.Aim. To develop a methodology for calculating driven precast piles for the action of frost heaving tangential forces during CSM freezing.Materials and methods. A set of laboratory tests, modeling the processes in soils during cold and warm pile installation periods, was carried out. Laboratory tests were performed using a method of a single-plane cut along the surface of a CSM freezing with clay soils, as well as with the foundation material at a constant rate in accordance with State Standard R 56726-2015 and statistical data processing according to State Standard 20522-2012.Results. The article presents the results of laboratory studies on effects, caused by frost heaving tangential forces on piles during soil and CSM freezing, taking into account various factors (clay soil liquidity index, test temperature). Based on the obtained data, the authors propose a methodology for calculating the stability of driven precast piles. The method consists in determining the heaving force per unit area by adding the products of the seasonal freezing-thawing fractional depth, obtained by thermal engineering calculations or according to the plots, given in the article, by the tangential forces of frost heaving, obtained in laboratory studies.Conclusions. The developed methodology improves the reliability and accuracy of foundation calculations, enhances the efficiency of base and foundation design solutions, and reduces the labor capacity of driven precast pile installation.

Особенности применения теплоизоляционных материалов в строительстве

The choice of thermal insulation materials in the design is significantly influenced by both physical and economic features. Using the calculation program "LIT THERMO ENGINEER Enclosing structures", a thermal engineering calculation of enclosing structures was performed, the result of which is the thickness of the thermal insulation material. A comparative analysis of thermal insulation materials according to the criteria of flammability, cost and coefficient of thermal conductivity is performed. As a result, conclusions and recommendations on the use of the considered thermal insulation materials at the design stage are given.

ENERGY SAVING TECHNOLOGIES IN THE CONSTRUCTION OF BUILDINGS AND STRUCTURES IN THE TERRITORY OF UKRAINE

Purpose. Analysis of the main advantages of innovative technologies of energy efficiency and thermal efficiency of construction and reconstruction of buildings and structures at various stages of construction. Methodology. Along with the spread of organizational processes of technology and construction organization of modern well-known. Construction is one of the largest consumers of energy resources (up to 40%). Construction is one of the most important areas of the country’s economy, which must provide the necessary conditions for saving electricity consumption during construction and the further use of energy-saving and heat-saving technologies, taking into account the environmental consequences of construction and the climatic conditions of the construction site. Energy efficiency and thermal efficiency is becoming one of the main issues for the economic, ecological and social development of construction in Ukraine. Findings. The paper analyzes the use of innovative energy-saving and heat-saving technologies in the construction and reconstruction of buildings and structures, and the material provided can be used by the teacher of construction technologies in practical work for training students. Originality. The factors – architectural, design, construction, materials, which affect the energy efficiency and thermal efficiency of the construction – have been determined, and the provided material can be used by the teacher of construction technologies in practical work for the training of students. Practical value. The thermal properties of the enclosures must ensure a standardized temperature and humidity regime in the room, the permissible value of temperature fluctuations on the inner surface with temperature changes of the outside air. The purpose of carrying out thermal engineering calculation of energy-efficient enclosing structures of buildings is to ensure increased thermal protection of residential buildings and structures for new construction, reconstruction and major repairs.

The Influence of “Green” Roofs on the Energy Efficiency of Residential Buildings in the City of Tula

The need to improve the thermal engineering characteristics of the enclosing structures of construction objects and the increasing interest of the state in the development of environmental policy increase the prospects for studying the technology of “green” roofs because they are capable to solve comprehensively issues of energy efficiency and environmental safety. The object of the study is modern technological solutions of “green” roofs, the subject of the study is the analysis of the thermo-physical properties of coatings using “green” roof systems, the objectives of the study include: justification of the need to implement the above systems in the current climatic conditions, market analysis of the solutions offered by leading manufacturers of “green” coatings, the implementation of comparative thermal engineering calculations, calculations of stationary and non-stationary heat transfer in the thickness of coating structures. In the course of the study, data from official statistics websites, publicly available satellite images of remote sensing and also mathematical analysis methods, including methods of correlation and regression analysis, forecasting trends based on the obtained indicators were used. To perform the calculations, the Excel software package and the ELCUT engineering analysis computer program that allows two-dimensional modelling in solving thermal problems were used. Statistical data on the provision of residents of the region with public green spaces have been formed and analysis of the environmental parameters of the territory was carried out with the creation of a correlation and regression model, also forecast values. The results of the temperature distribution fields for stationary and non-stationary heat transfer of two types of “green” roof construction are obtained, taking into account various parameters of finishing the inner surface of the coating. Statistical environmental data that was generated using mathematical analysis methods made it possible to determine the environmental risks of the region, to create a basis for further research on the territory of the Tula region. The energy efficiency indicators of various types of “green” roofs, obtained as a result of thermal engineering calculations, as well as the identified accumulation capabilities, allowed us to draw conclusions about the prospects for the introduction of “green” technologies and the need for further research in the field of energy conservation and thermal inertia of enclosing structures of construction objects.

Studying the thermal characteristics and effectiveness of structural fire proofing made of PROSASK Firepanel cement boards by means of reproducing the high-temperature effect

Introduction.The application of PROZASK fire-retardant panels demonstrates an option for and the expediency of a comprehensive study of fire proofing characteristics.Goals and objectives.The mission of this research project is to (1) obtain the results of experimental studies of fireproofing panels, containing the cement binder, (2) determine their fire proofing efficiency, using the radiant heating test bench that reproduces pre-set modes of high-temperature exposure, and (2) analyze the testing results using the method of mathematical modelling of temperature fields inside fireproof structures.Methods.Standardized laboratory techniques were used to clarify the thermal-physical characteristics of boards at relatively low temperatures. Their fire proofing efficiency was evaluated in the course of additional testing of specimens using the radiant heating test bench. A reliable and relatively uncomplicated method and programme for calculating unsteady temperature fields in fireproof structures were used to conduct the thermal analysis and generalization of experimental results. The authors summarized the results of standardized tests, conducted in a fire furnace, to determine the flame-retardant efficiency of PROZASK Firepanel boards and the fire-resistance of the full-size structures they protect.Results.Values of specific heat capacity and the thermal conductivity coefficient of boards, tested using laboratory benches at relatively low temperatures, were verified. The results of thermocouple measurements, taken during the testing of specimens with the help of the radiant heating bench in standard and hydrocarbon temperature modes, were obtained. The processing of these results, using thermal engineering analysis, allowed determining the values of the thermal conductivity coefficient in the range of operating temperatures. The influence of moisture, contained in the boards, on their fire protection efficiency was evaluated. Comparison between the results of calculations and tests, conducted in the fire furnaces, showed the practical usability of the obtained characteristics of boards and the thermo-engineering analysis used to (1) clarify the fire-proofing efficiency and the design developed using PROZASK Firepanels and (2) evaluate the fire-resistance of the constructions they protect.Conclusions.The presented integrated studies generated a considerable amount of important information, required to prognosticate the fire proofing properties and the fire-resistance of constructions that contain PROZASK Firepanels. The role of additional testing of specimens using a radiant heating test bench and the effectiveness of thermal-engineering calculations as a tool for assessing the parameters of fire proofing and the fire resistance of structures are demonstrated.

Refinement of thermal engineering calculations results taking into account actual materials characteristics

The article presents the laboratory studies results of building materials thermophysical characteristics used in the construction of experimental wooden buildings. In the framework of laboratory experiments, the thermal conductivity and humidity of structural and thermal insulation materials samples were evaluated. The analysis and comparison of the results obtained with the characteristics of the materials declared by the manufacturers and in the reference data is carried out. The results of thermal engineering calculation refinement of the of the enclosing structures of experimental wooden buildings, taking into account the results of laboratory studies of the thermophysical characteristics of building materials used in construction, are presented. The thermal engineering calculation of the enclosing structures of the frame part of experimental buildings has been refined taking into account the actual thermal conductivity of building materials. The influence of the actual thermophysical characteristics of building materials on the results of thermal engineering calculation in comparison with the design values was evaluated. Further directions of research are presented in terms of the influence of cold bridges and inhomogeneities of structures on the thermal characteristics of the thermal contour of the building.

THERMAL BALANCE OF A HOUSE WITH AIR SOLAR COLLECTOR AND HEAT STORAGE FOR THE CONDITIONS OF THE BAIKAL NATURAL TERRITORY

In this work, thermal engineering calculations of the energy efficiency of a low-rise house made of timber, insulated with mineral wool for the conditions on Lake Baikal, were carried out. As a prototype for determining the thermal characteristics, an information model of a building typical of the island in terms of architecture and size was developed using BIM technology. The engineering equipment additionally includes an air solar collector and a heat storage device in the form of a heat-insulated soil massif. Two variants of operation are considered. In the first case, the house is operated as housing for five people, and in the second case as a hotel for ten people. The analysis of energy costs for heating for individual months and for the year as a whole was carried out. The heat consumption for heating the ventilation air and its share in the total heat costs in the mode of a residential building and a hotel are determined. The possibility of a significant reduction in energy consumption when using the heat recovery of ventilation air is shown. An additional reduction in energy consumption from traditional heating systems through the use of an air solar collector is considered. It is shown that the accumulation of excess heat by a special thermally insulated array of soil under the house leads to the stabilization of the thermal regime. The specific characteristic of heat consumption by the house is determined.

Analyzing the fire performance of concrete columns and slabs under loading and using options, preventing explosive spalling to ensure the pre-set fire resistance

Introduction. The authors focus on preventing the explosive spalling of concrete and the fireproofing of reinforced concrete structures. The relevance of this issue is explained by the insufficient number of fire tests of such structures under loading and thermal engineering calculations, needed for an objective analysis of testing results.Goal and objectives. The authors analyze the results of a series of fire tests, involving concrete columns and slabs with and without polypropylene microfiber, if no fireproofing is applied, as well as the results of the same tests involving the same items fireproofed by plates or plaster.Methods. The fire resistance of full-scale specimens of concrete was evaluated according to a standardized testing in a fire furnace under loading. It encompasses additional thermocouple measurements used to make a thermal engineering analysis. The analysis entailed both one- and two-dimensional problem formulations, methods and programmes for the numerical computation of non-stationary temperature fields in fireproof structures.Results. New data, obtained in the course of the fire experiments, show the efficiency of the polypropylene microfiber used to prevent the explosive spalling of concrete. The fire resistance limit is R 120 and R 150 under constant static loading. The fire resistance limit of similar structures, fireproofed by PROSASK Firepanel plates or IGNIS LIGHT plaster, was demonstrated. The specimens show the efficiency of methods and programmes for the one- and two-dimensional numerical analysis of non-stationary temperature fields in fireproof structures. The calculation results are presented for various fireproofing options.Conclusions. The testing results and their thermal analysis represent important items of information necessary to ensure the fire safety and the pre-set fire resistance of concrete structures under loading. They can also be used to outline the development pattern of this experimental and theoretical research project. The efficiency of thermal engineering calculations as a tool for evaluating fire protection parameters and the fire resistance of concrete structures is demonstrated, also as an option to reduce the number of expensive fire tests.

Research of Fire Resistance of Fire Protected Reinforced Concrete Structures

A finite element model for thermal engineering calculation of fire-resistant multi-hollow reinforced concrete floor in the ANSYS software package has been developed. The model allows to evaluate the fire resistance of fire-resistant and unprotected reinforced concrete structures both under load and without it. With the help of the developed model, the heat engineering calculation of the fire-resistant reinforced concrete multi-hollow slab was carried out. The results of numerical simulation are compared with the results of experimental study of fire resistance. An approach is proposed that allows to take into account all types of heat transfer by specifying cavities as a solid body with an equivalent coefficient of thermal conductivity. The adequacy of the developed model was checked, as a result of which it was established that the calculated values of temperatures correlate satisfactorily with the experimental data. The largest deviation in the measurement of temperatures is observed at 100 minutes of calculation and is about , which is 9%.

Сalculation of fire resistance of fire protected reinforced concrete structures

A finite-element model was developed for thermal engineering calculation of a fire-resistant multi-cavity reinforced concrete floor in the ANSYS software complex. With the help of the developed model, a thermal engineering calculation of a fire-resistant reinforced concrete multi-hollow floor slab was carried out, the essence of which was to solve the problem of non-stationary thermal conductivity and was reduced to determining the temperature of the concrete of the reinforced concrete floor at any point of the cross section at a given time (including at the place of installation of the fittings).A comparison of the results of numerical modeling with the results of an experimental study of fire resistance was carried out. An approach is proposed that allows taking into account all types of heat exchange by specifying cavities as a solid body with an equivalent coefficient of thermal conductivity. The model makes it possible to study stationary and non-stationary heating of both unprotected and fire-protected reinforced concrete structures. At the same time, with the help of the developed model, it is possible to take into account various factors affecting fire-resistant reinforced concrete structures: fire temperature regimes, thermophysical characteristics of reinforced concrete structures, coatings for fire protection of reinforced concrete structures. The adequacy of the developed model was tested, as a result of which it was established that the calculated values of temperatures satisfactorily correlate with experimental data. The largest area of deviation in temperature measurement is observed at the 100 th minute of calculation and is about 3 ºС, which is 9 %. The workability of the developed model for evaluating the fire resistance of fire-resistant reinforced concrete structures and its adequacy to real processes that occur during heating of fire-resistant reinforced concrete structures with the application of a load under the conditions of fire exposure under the standard fire temperature regime have been proven.

Thermodynamic Aspects of Pavement Engineering

Scientific and practical calculations on the thermal stability of typical automobile road surface (semi-limited objects) with fluctuations in air temperatures, transitions from positive to negative, with actual heat transfer coefficients, thermal conductivity of components, specific mass isobaric heat capacities, material densities, periods of regular fluctuations are presented. The study shows that temperature fluctuations occur in road surfaces, therefore deformations are brought about in them, generating thermal cracks. Thermal deformations include free, proportional to temperature gradients, stressed deformations due to temperature stresses, characterized by linear thermal expansion coefficients. In road materials, physical and mechanical properties change over time: strength, moduli of elastic longitudinal deformations, shear, transverse deformation coefficients. Thus, the temperature of pavement materials depends on the coordinates, time, and thermophysical characteristics of the materials. Thermal engineering calculations have shown that many road surfaces have limited thermal stability; under the influence of relatively small external influences, they are more stable (supercooled water vapor exists for a short time, turning into a liquid, saturated, supersaturated steam into a superheated liquid, this depends on the radiation characteristics of the surfaces, the presence of external disturbances, etc.). Thus, a complex non-stationary thermal regime takes place, when the temperature fields of the coatings, their gradients of temperature potentials, and masses depend on the boundary conditions of the 1st–4th kind. A citation analysis of the data of the Journal Citation Reports of world scientific serial publications has been developed to carry out research on heat and mass transfer in road surface. The analysis shows that in order to improve the reliability and durability of pavements, fundamental studies of both the physical and technical and thermal properties of all components of road construction mixtures are of great importance.

ЭНЕРГОЭФФЕКТИВНЫЕ ЗДАНИЯ НА ОСНОВЕ ТРАНСФОРМИРУЕМЫХ КАРКАСОВ

. In the construction industry, buildings that provide themselves with energy are increasingly appearing. The article discusses the formative capabilities of the kinematic system, presents lattices and the three-dimensional shapes obtained from them. Special attention is paid to the cylindrical surface, its geometric immutability is ensured by the rigidity of the contour and the spatial shape of the surface of the central part. The authors of the article proposed a public building based on a transformable frame – it is a quick-erect and lightweight spatial structure that will meet the three main requirements of modernity: energy conservation, eco-nomicity and environmental friendliness. Have created a three-dimensional model of the structure, viewed in two states: before construction (flat rectilinear lattice) and after construction. The selection of enclosing structures based on thermal engineering calculations was carried out, and solar panels are used as additional panels. The color scheme of the facades is proposed. The light openings are triangular in shape on the side facade and trapezoidal with triangular at the ends of the building. This solution is due to maintaining the rhythm of structures and sandwich panels. installation of additional internal supports. The absence of internal supports in the building provides freedom in planning issues. To generate an alternative type of energy and save money, solar panels are installed on the building so as not to violate the general concept of facades.

Оцінювання вогнестійкості вогнезахищених сталевих балок

Purpose. Development of a computer model for the study of fire resistance of steel structures protected by fire-resistant coatings, using the example of a fire-resistant steel beam created in the LIRA-SAPR software complex (Ukraine). Methods. Finite element method, application of computational methods of numerical modelling of the LIRA-SAPR software complex, mathematical modelling of thermal processes of non-stationary thermal conductivity. Results. A computer model was developed in the LIRA- SAPR software complex, with the help of which thermal engineering calculation of the beam was carried out. The model makes it possible to evaluate the fire resistance of both unprotected and fire-protected steel beams, to take into account the properties of the beam material and the material of the fire-resistant coating. The peculiarity of modelling the non-stationary heating of a fire-resistant steel beam is to specify the thermophysical characteristics of the fire-resistant coating when solving the problem of non-stationary thermal conductivity. The results of the calculated determination of the fire resistance of the fire-resistant steel beam were compared with experimental data. As a result, a satisfactory convergence of the results of the calculation and experimental study of fire resistance was established (the error is no more than 12%). The results of the experimental determination of the fire resistance of unloaded beams under fire conditions of the standard fire temperature regime were analysed. The accuracy of the developed computer model was evaluated with the results of the experiment. Scientific novelty. A finite-element model of a fire-resistant steel beam has been developed in the LIRA- SAPR software complex, which allows calculating the fire resistance limits of beams protected by fire-resistant coatings with scientifically justified parameters with sufficient accuracy for engineering calculations. Practical significance. It consists in creating the basis for the calculated assessment of fire resistance of building structures protected by fire-resistant coatings by creating computer models capable of performing fire resistance calculations. Due to this, there should be a significant reduction in the cost of work on fire resistance assessment and, as a result, an increase in the effectiveness of measures to increase the fire resistance of building structures.

Reducing construction costs by optimizing fencing structures on the example of block-modular buildings

The introduction of modernized (improved) and new technologies is necessary to improve the quality of construction with a reasonable reduction in costs and terms of block-complete construction (BCS). There are various BCS technologies that combine known and developed methods and methods. Therefore, in order to increase the efficiency of construction, it is necessary to solve a number of tasks: to calculate the enclosing structures at BCS in accordance with their requirements for thermal protection, to determine the economic feasibility of the measures under consideration. On the example of a research object, the choice of enclosing structures is presented in order to reduce capital costs. If the tasks are successfully solved, it will be possible to offer the restoration of objects destroyed by natural disasters, BCS of new buildings, as well as during the reconstruction of objects. The article presents: the object of research "Compressor station in the area of BPS-2 X field"; block buildings located on the site of the booster pump station are considered; the characteristics of the enclosing structures of the "sandwich" type with various heaters are given; their thermal engineering calculation and comparative analysis of the efficiency of the heat-insulating material were carried out. Conclusions, methods and ways of solving BCS problems are presented; modernization of construction technologies.

Assessment of heat protection characteristics of building enclosing structures of the building of the men’s monastery

The article presents the results of a thermal imaging study and thermal engineering calculation of the building enclosing structures of the monastery hotel building in the village of Vinnovka, Stavropol district, Samara region. The survey was conducted in order to determine the causes of low temperatures in the hotel premises. According to SP 50.13330.2012 Thermal protection of buildings, energy saving standards in construction do not apply to religious buildings. The level of thermal protection of the above buildings is determined by the provision of modern sanitary and hygienic standards. Based on computer simulation of temperature fields in the outer walls, made in the form of well masonry with the use of polystyrene concrete as insulation, it was found that the value of the reduced resistance to heat transfer they meet regulatory requirements. The actual values of the reduced resistance to heat transfer of the exterior walls, obtained by the results of thermal imaging examination, in the lower part of the exterior walls in individual rooms were significantly lower than the standard ones, which leads to increased heat loss and, as a consequence, to cooling of the indoor air. The reasons for the lowered air temperatures in the hotel premises have been established and recommendations have been developed to eliminate the above-mentioned defects.

Effect of uncertain hydrothermal properties and freezing temperature on the thermal process of frozen soil around a single freezing pipe

Thermal engineering calculation of one-dimensional (1-D) freezing is an important evidence for the evaluation of heat conduction process of artificial ground freezing (AGF). In this work, an array of field experiments of the 1-D freezing processes were carried out, and the coefficient of variation (COV) and scale of fluctuation (SOF) of uncertain hydrothermal properties were obtained. A1-D stochastic hydrothermal model was proposed, and the uncertain thermal processes are computed by a self-compiled program. A model validation and comparison with the experimental and numerical temperatures were presented. According to the relationship between autocorrelation distance (ACD) and SOF for the five autocorrelation functions (ACFs), the effects of the ACF, COV and ACD of hydrothermal properties and the COV of freezing temperature on the 1-D freezing thermal process were analyzed. The results show that moisture transfer can promote the heat transfer process. The thermal process of phase change is unsteady and the corresponding standard deviation (SD) is greater. The effects of ACF of hydrothermal properties on random thermal process are insensitive. The larger the COV of freezing temperature or hydrothermal property, the larger the SD of temperature. The larger the ACD of hydrothermal property, the smaller the SD of temperature.