Thermal Stability Influence of the Enclosure Structure on the Building s Energy Efficiency

Transcription

1 Termal Stability Influene of te Enlosure Struture on te Building s Energy Effiieny Daria Zaborova 1,*, Marina Petroenko 1 and Ludmila Cernenkaya 1 1 Peter te Great Saint-Petersburg Polyteni University, Polytenieskaya str. 29, St. Petersburg, Russia Abstrat. Termal stability of te enlosure strutures is one of te most important objetive in te building design. Termal proesses in te wall depend not only on te internal and external air temperature, but also on many oter fators. Terefore, omplexity of tis proess make eat onservation in te room to be an atual problem. Tis paper presents dependene between termal stability of te enlosure struture and its design. It was sown tat termopysial arateristis of materials diretly affet te termal proesses in te wall. For te resear, tree frequently used types of enlosure struture in Russia were taken. For ea wall was found te average temperature and ooling time. As a result, it was found tat te iger values of termal ondutivity, speifi eat and material density are, te iger average temperature of te wall is. 1 Introdution Nowadays te problem of energy effiieny is one of te most disussed issues [1-5]. Espeially for Russia, effetive use of te fuel and natural resoures is te main task. Te main objet of energy onsumption is residential building. Approximately, energy onsumption for eating buildings is about 4% of all extrated fuel [6]. Te main energy task in te onstrution industry is design of buildings and onstrutions wit effetive use of energy [7, 8]. It is known tat te biggest eat loss is troug te walls. Terefore, mu attention is paid to design te enlosure strutures. Works of many people are devoted to te solution of tis problem [9-13]. Operating priniple of te enlosure struture is to keep eat in te ouse as long as possible [14-16]. For tis reason, it is so important tat material an be able to resist te stresses aused by ange of temperature. Termopysial properties of strutures and materials were investigated in works of G.M. Kondratyev, V. N. Bogoslovsky, G.N. Dulnev [17], Y. A. Tabunsikov [18], A. S. Gorskov [19, 2]. Tese materials sow te importane of eat transfer problem in strutures. 1.1 Purposes and objetives Te purpose of te study is to establis te onnetion between te energy effiieny of te enlosure struture and its termal stability. Tus, te following tasks ave been set: Te Autors, publised by EDP Sienes. Tis is an open aess artile distributed under te terms of te Creative Commons Attribution Liense 4. (ttp://reativeommons.org/lienses/by/4./).

2 1. To estimate dynami of anges te average stationary temperature in multi-layer walls of different design; 2. To evaluate influene of termal resistane on te enlosure struture average temperature. 1.2 Resear desription Tanks to introdution of new rules for eat resistane of enlosure strutures and inreases ost of energy, in Russia is beoming more and more popular use of ligtweigt onrete in onstrution [21, 22]. In addition, su materials as reinfored onrete and brik do not maintain te requirements for termal resistane any more. To ompare wat wall aumulates eat better we ose tree different materials: ligtweigt onrete, brik and reinfored onrete. For tis study were seleted tree types of enlosure struture wi are frequently used in onstrution (Fig. 1, 2, 3). Fig. 1. Wall 1. Fig. 2. Wall 2. Fig. 3. Wall 3. First type of te enlosure struture onsists of tree layers and as a total tikness 595 mm (Fig.4). Te struture of te wall is sown below. Fig. 4. Te setion view of te wall 1 by layers. Outdoor is on te left. Te termal arateristis of materials are given in table 1. 2

3 of layer Layer of material Table 1. Termal arateristis of materials. Layer tiknes s, Coeffiient of termal ondutivity, Speifi eat, p Density, ρ Coeffiient of termal absorption, β [m] [W/m C] [J/kg C] [kg/m 3 ] [J/ s m 2 C] 1 Aerated onrete Mineral wool Cerami brik Seond type of te enlosure struture onsists of tree layers and as a total tikness 47 mm (Fig.5). Te struture of te wall is sown below. Fig. 5. Te setion view of te wall 2 by layers. Outdoor is on te left. of layer Te termal arateristis of materials are given in table 2. Layer of material Table 2. Termal arateristis of materials. Layer tikness, Coeffiient of termal ondutivity, Speifi eat, p Density, ρ Coeffiient of termal absorption, β [m] [W/m C] [J/kg C] [kg/m 3 ] [J/ s m 2 C] 1 Siliate brik Polystyrene foam Siliate brik Tird type of te enlosure struture onsists of tree layers and as total tikness 47 mm (Fig.6). Te struture of te wall is sown below. 3

4 Fig. 6. Te setion view of te wall 3 by layers. Outdoor is on te left. of layer Te termal arateristis of materials are given in table 3. Layer of material Table 3. Termal arateristis of materials. Layer tikness, Coeffiient of termal ondutivity, Speifi eat, p Density, ρ Coeffiient of termal absorption, β [m] [W/m C] [J/kg C] [kg/m 3 ] [J/ s m 2 C] 1 Reinfored onrete Mineral wool Siliate brik Internal oeffiient of eat transfer int, W/ (m 2 C) demonstrates te ability of material to absorb eat wen temperature flutuates on its surfae and an be found by te formula: were t - flutuation period of a termal steam, s; int ρ p, (1) t β ρ p - oeffiient of termal absorption, J/( s m 2 C). Tus, te eat absorption of onstrution depends on pysial properties of material. 2 Calulations of te wall average temperature Beause te multilayer walls onsist of different layers, te oeffiients, ρ,p are anged disretely. Wit great number of layers, te disrete distribution an be replaed by a ontinuous distribution, and from summation turn to integration of ontinuous distributions. 4

5 i x i dx R, (2) were R wall eat transfer resistane, (m 2 C)/W. We determined te average stationary temperature for ea type of wall by te formula: T T dx T 1 dx 1 x x T T dx 1 x 1 ξ ξ dξ, (3) were = 23 W/(m 2 С) - outer surfae eat transfer oeffiient of te building envelope; = 8.7 W/(m 2 С) - inner surfae eat transfer oeffiient of te building envelope; T - te internal air temperature in te premises of a residential building in St. Petersburg, taken in aordane wit GOST 3494 at 2 C; T - te average montly outdoor air temperature in January, taken in aordane wit SNIP * at -8.7 C; - tikness of te wall, m; - termal ondutivity, W/(m C). Te alulation results are summarized in Table 4. Table 4. Average temperature of enlosure struture. Average stationary temperature Sample 1 Sample 2 Sample 3 T, C Calulations ave sown tat te wall wit te igest termal ondutivity as te igest average temperature. Influene of wall eat ondutivity on its average temperature is sown in Figure 7. Fig. 7. Dependene of average temperature on eat ondutivity oeffiient. Now we determine te instantaneous average temperature of te wall: T (T T ) θ T. (4) Temporary measure of termal stability - θ an be found by te formula (4). t t θ exp, (5) t t 5

6 were t - ooling time of te wall, s. Te value of t and t were determined from te following equations: t t ρp, (6) ρ p. (7) Te results of alulation for ea onstrution type are summarized in table 5. Table 5. Instantaneous average temperature. Time, ours Wall 1 Wall 2 Wall 3 Time, ours Wall 1 Wall 2 Wall Time-average temperature transformation in all free types of enlosure struture are presented in Figure 8. Temperature, C Mean temperature Time, ours Wall 1 Wall 2 Wall 3 Fig. 8. Cooling time of te walls. 6

7 3 Conlusions 1. Te results of alulations sowed tat reinfored onrete wall as te igest average temperature 8.89 C. Te aerated onrete wall as te lowest average temperature 5.22 C. Tese values onfirm tat wall wit big oeffiient of termal absorption β as a iger average temperature tan wall wit small oeffiient of termal absorption. 2. Aerated onrete wall ools mu faster tan wall made from brik or reinfored onrete. 3. Heat aumulation is very important for energy saving and reation te optimal limate in te ouse. However, despite te small oeffiient of termal ondutivity, eat storage apaity of aerated onrete is less tan in reinfored onrete wall. From te standpoint of energy effiieny, reinfored onrete wall is unreasonable. However, from te standpoint of termostability tis is reasonable wall. Referenes 1. V. Murgul, JAES, 12 (1), 1-1, (214) 2. M.V. Knat'ko, M.N. Efimenko, A.S. Gorskov, MCE, 2, 5-53, (28) 3. D. Nemova, V. Murgul, A. Golik, E. Cizov, V. Pukkal, N. Vatin, JAES, 12 (1), 37-44, (214) 4. A. Gorskov, N. Vatin, D. Nemova, A. Sabaldin, L. Melnikova, K. Paramonov, Proedia Eng., 117, , (215) 5. L. Svatovskaya, A. Syova, M. Syov, V. Okrepilov, MATEC Web of Conferenes, 53, Artile Number 123 (216) 6. E. Perlova, S. Karpova, X. Rakova, E. Bondarenko, M. Platonova, A. Gorskov, AMM, , , (215) 7. A. Lupíšek, M. Bureša, M. Volfa, J. Hodkováa, J. Nováčeka, P. Hejtmáneka, J. Tywoniak, Energy Proedia, 78, , (215) 8. J. Tywoniak, K. Sojková, Energy Proedia, 78, , (215) 9. D.V. Petrosova, N.M. Kuz'menko, D.V. Petrosov, MCE, 8, 31-37, (213) 1. E. Kosseka, J. Kosny, J. Term. Envelope Build. Si., 7, , (1998) 11. S.V. Korniyenko, MCE, 8, 25-37, (214) 12. J. Carmeliet, H. Hens, C. Vermeir, Resear in building pysis, (23) 13. Medved, A. Trnik, Termopysis and Mass Transfer in Materials Siene and Constrution, (215) 14. M. R. Hall, Materials for energy effiieny and termal omfort in buildings, (21) 15. S. Kubba, Green building design and onstrution, (212) 16. P. Glover, Building surveys 7 edition, (28) 17. G.N. Dul'nev, D.P. Volkov, V.I. Malarev, V.I. Malarev, J. Eng. Pys. Termopys., 56 (2), , (1989) 18. G.P. Vasilyev, V.A. Liman, M.V. Kolesova, N.V. Peskov, M.M. Broda, Y. A. Tabunsikov, Energy Build., 86, 83-87, (215) 19. N.I. Vatin, A.S. Gorskov, D.V. Nemova, A. A. Starityna, D. S. Tarasova, Adv. Mater. Res., , 95-92, (214) 2. N.I. Vatin, D.V. Nemova, P.P. Rymkevi, A.S. Gorskov, MCE, 8, 4-14, (213) 21. A.S. Gorskov, P.P. Rymkevi, N.I. Vatin, MCE, 8, 38-48, (214) 22. N.I. Vatin, A.S. Gorskov, D.V. Nemova, Constr. of Unique Build. and Str. 3 (8), 1-11, (213) 7