DESIGNING AND DETAILING OF BUILDING SYSTEMS. MECHANICS IN CIVIL ENGINEERING

Thermotechnical analysis of the structuresby using numerical methods

Vestnik MGSU 11/2013
  • Tusnina Olga Alexandrovna - Moscow State University of Civil Engineering (MGSU) postgraduate student, Department of Metal and Timber Structures, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 91-99

In the paper the features of a structural thermotechnical analysis with the use of numerical methods are considered. Characteristics of heat transfer processes can be obtained using experimental or theoretical analysis. A theoretical investigation works with mathematical model, not with real physical phenomenon. The mathematical model for heat transfer processes consists of a set of differential equations. If the methods of classical mathematics are used for solving these equations, many phenomena of practical interest will be predicted. That’s why in order to solve these problems it is advisable to apply numerical methods. In this paper an algorithm of numerical calculation of threedimensional temperature fields is considered.The numerical algorithm for solving the differential equation of steady three-dimensional thermal conductivity is represented. Discretization of this equation was performed by control-volume method. A solution of a set of discretized equations can be obtained by using a convenient combination of the direct method TDMA (Tri-diagonal matrix algorithm) for one-dimensional situation and the Gauss-Seidel method. The described approach allows us taking into consideration thermal inhomogeneity, such as thermal bridges, and the features of the geometry of the structure. The computing program TEPL was developed on the basis of the described algorithms. As a result of the calculation made by TEPL three-dimensional temperature field was obtained. On the basis of this field thermal resistance and temperature distribution in the structure were calculated.The examples of using the program for solving real practical problems are shown in the paper. Roofing consisted of sandwich panels supported by purlins with the use of screws in one case and rivets as fasteners in the other. The main difference between these two structures is that screws are installed through the insulation layer of a panel and violate its integrity, while rivets are connected to the lowest sheet of a panel and purlin flange and do not make any changes in insulation. The results of the numerical analysis in TEPL show that screws are thermal bridges and must be taken into account in the process of calculating thermal resistance of roofs.

DOI: 10.22227/1997-0935.2013.11.91-99

References
  1. Krivoshein A.D., Fedorov S.V. K voprosu o raschete privedennogo soprotivleniya teploperedache ograzhdayushchikh konstruktsiy [On the Question of Calculating Reduced Thermal Resistance of Building Envelopes]. Inzhenerno-stroitel'nyy zhurnal [Magazine of Civil Engineering]. 2010, no. 8, pp. 21—27.
  2. Tusnin A.R. Proektirovanie sten s okonnymi proemami [A Design of Walls with Window Openings]. Stroitel'stvo i nedvizhimost' [Construction and Real Estate]. 1997, no. 12, p. 7.
  3. Tusnin A.R., Tusnina V.M. Soprotivlenie teploperedache sten s okonnymi proemami [Thermal Resistance of Walls with Window Openings]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, no.1, vol. 2, pp. 123—129.
  4. Gorshkov A.S. Energoeffektivnost' v stroitel'stve: voprosy normirovaniya i mery po snizheniyu energopotrebleniya zdaniy [Energy Efficiency in Construction: Issues of Regulation and Measures to Reduce the Energy Consumption of Buildings]. Inzhenerno-stroitel'nyy zhurnal [Magazine of Civil Engineering]. 2010, no. 1, pp. 9—13.
  5. Kraynov D.V., Safin I.Sh., Lyubimtsev A.S. Raschet dopolnitel'nykh teplopoter' cherez teploprovodnye vklyucheniya ograzhdayushchikh konstruktsiy (na primere uzla okonnogo otkosa) [Calculation of Additional Conductive Heat Loss through the Building Envelope Inclusions (on the Example of a Window Unit Slope)]. Inzhenerno-stroitel'nyy zhurnal [Magazine of Civil Engineering]. 2010, no. 6, pp. 17—22.
  6. Ben Larbi A. Statistical Modelling of Heat Transfer for Thermal Bridges of Buildings. Energy and Buildings. 2005, vol. 37, no. 9, pp. 945—951.
  7. Karabulut K., Buyruk E., Fertelli A. Numerical Investigation of Heat Transfer for Thermal Bridges Taking into Consideration Location of Thermal Insulation with Different Geometries. Strojarstvo. 2009, vol. 51, no. 5, pp. 431—439.
  8. Svoboda Z. The Analysis of the Convective-Conductive Heat Transfer in the Building Constructions. Proceedings of the 6th Int. IBPSA Conference Building Simulation, Kyoto. 1999, vol. 1, pp. 329—335.
  9. Ait-Taleb T., Abdelbaki A., Zrikem Z. Coupled Heat Transfers through Buildings Roofs Formed by Hollow Concrete Blocks. International Scientific Journal for Alternative Energy and Ecology. 2008, no. 6 (62), pp. 30—34.
  10. Gladkiy S.L., Yasnitskiy L.N. Reshenie trekhmernykh zadach teploprovodnosti metodom fiktivnykh kanonicheskikh oblastey [The Solution of Three-dimensional Heat Conduction Problems Using Fictitious Canonical Regions Method]. Vestnik Permskogo universiteta. Matematika. Mekhanika. Informatika [Proceedings of Perm Univercity. Mathematics. Mechanics. Computer Sciences]. 2011, vol. 1(5), pp. 41—45.
  11. Belostotskiy A.M., Shcherbina S.V. Sravnitel'nye raschetnye issledovaniya energoeffektivnosti sushchestvuyushchikh i vnov' razrabotannykh materialov i konstruktsiy na osnove konechnoelementnogo modelirovaniya dvumernogo i trekhmernykh zadach teploprovodnosti [Comparative Study of the Energy Efficiency of Available and Newly Developed Materials and Structures Based on the Finite-element Resolution of 2d and 3d Problems of Heat Conductivity]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2013, no. 3, pp. 212—219.
  12. Patankar S. Chislennye metody resheniya zadach teploobmena i dinamiki zhidkosti [Numerical Methods of Solving the Problems of Heat Transfer and Fluid Flow]. Moscow, Energoatomizdat Publ., 1984, 150 p.

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STUDY OF CRYSTALLIZATION OF CALCIUM SULFATE DIHYDRATE THAT HAS POLYMER ADDITIVES

Vestnik MGSU 7/2012
  • Ustinova Yuliya Valer'evna - Moscow State University of Civil Engineering (MSUCE) +7 (499) 183-32-92, Moscow State University of Civil Engineering (MSUCE), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
  • Sivkov Sergey Pavlovich - D. Mendeleyev University of Chemical Technology of Russia (MUCTR) 8 (495) 496-92-38, D. Mendeleyev University of Chemical Technology of Russia (MUCTR), 20 Geroev Panfilovtsev str., Moscow, 125047, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
  • Aleksashin Valeriy Mikhaylovich - All- Russian Scientific Research Institute of Aviation Materials Candidate of Technical Sciences, Senior Researcher, +7 (499) 263-89-02, All- Russian Scientific Research Institute of Aviation Materials, 7 Radio St., Moscow, 105005, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 130 - 135

Currently, functional additives represented by many classes of substances and compounds, including polymers of different origin, are widely used in the production of dry mixtures based on gypsum binders. However, the impact of these additives produced on the formation of calcium sulfate dihydrate (CaSO42H2O) crystals in the course of the hardening of gypsum binders, is not quite clear. Therefore, the research is aimed at the clarification of the processes of growth and formation of calcium sulfate dihydrate crystals in the presence of functional additives based on polymers of different origin. The research is composed of the following stages.
At the first stage, calcium sulfate dihydrate crystals were synthesized both in the pure form and with additives. The additives included super plasticizers based on sulfonated melamine-formaldehyde resin (SMF), methylcellulose (MC) and polymer powder based on copolymer of vinyl acetate, ethylene and vinyl chloride (VAEVC). At the second stage, X-ray analysis of the synthesized crystals was performed to identify potential patterns of influence produced by polymer additives onto the shape and size of calcium sulfate dihydrate crystals. At the third stage, thermal analysis and electron microscopy methods were applied to synthesized crystals.
The research suggests the following conclusions:
A. It is identified that additives based on polymers of different origin affect processes of crystallization, the size and shape of crystals.
B. The X-ray diffraction analysis has proven that molecules of polymer additives do not penetrate into the gypsum structure and the chemical composition of the product does not change.
C. Methods of thermal analysis have proven that the introduction of polymer additives does not produce any adverse impact on the stability of gypsum crystals, if exposed to temperature fluctuations.
D. The major impact produced onto crystallization is the one of the super plasticizer based on the sulfonated melamine-formaldehyde resin.

DOI: 10.22227/1997-0935.2012.7.130 - 135

References
  1. Korneev V.I., Zozulya P.V., Medvedeva I.N. Retsepturnyy spravochnik po sukhim stroitel’nym smesyam [Cookbook of Dry Building Mixtures]. St. Petersburg, 2010, RIA Kvintet Publ., 308 p.
  2. Izotov V.S. Khimicheskie dobavki dlya modifikatsii betona [Chemical Additives to Modify Concrete]. Moscow, Paleotip Publ., 2006, 244 p.
  3. Batrakov V.G. Modifitsirovannye betony. Teoriya i praktika [Modified Concretes. Theory and Practice]. Moscow, 1998, 768 p.
  4. Mishra R. K., Flatt R. J., Heinz H. Molecular Understanding of Directional Surface and Interface Tensions of Gypsum and Calcium Sulfate Hemihydrate. Proceedings of the XIII ICCC International Congress on the Chemistry of Cement. Madrid, Spain, 3-8 July, 2011.
  5. Butt Yu.M., Sychev M.M., Timashev V.V. Khimicheskaya tekhnologiya vyazhushchikh materialov [Chemical Technology of Binding Materials]. Moscow, Vyssh. shk. Publ.,1980, 472 p.

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