Time Dependent Surface Heat Transfer in Light Weight Aggregate Cement Based Materials
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Abstract
Surface temperature changes of building materials affect the calculation of heat flow and thus the energy use in heating and cooling. The surface heat transfer coefficient , limiting the heat flow between material surface and ambient air is normally taken as a constant. In this study we propose a time-dependent function . We estimate from unidirectional heat flow experiments with transient and steady-state conditions. Using temperature measurements and the conservation of energy at the surface including convective and irradiative boundary conditions, the value of was obtained both using Finite Difference and Taylor Polynomials methods. Numerical solutions of temperature distribution as function of time were improved with the obtained -functions compared to with constant . There were no clear difference between on different materials, and the final values observed were in the order of magnitude expected from the literature.
- D. M. Burch, D. F. Krintz and R. S. Spain, “The Effect of Wall Mass on Winter Heating, Loads and Indoor Comfort－An Experimental Study,” ASHRAE Transactions, Vol. 90, No. 2, 1984.
- J. E. Braun, “Reducing Energy Costs and Peak Electricity Demand through Optimal Control of Building Thermal Storage,” ASHRAE Transactions, Vol. 96, No. 2, 1990, pp. 876-888.
- F. Biasioli and M. Öberg, “Concrete for Energy Efficient and Comfortable Buildings,” Proceedings of International Conference on Sustainability in the Cement and Concrete industry, In: S. Jacobsen, P. Jahren and K. Kjellsen, Eds., Norwegian Concrete Association, Liilehammer, 2007, pp. 593-599.
- Ø Bjøntegaard, T. Kanstad and E. J. Sellevold, “Deformation Properties and Crack Sensitivity in Young Concrete: Experience from a 4-year R&D Project,” Proceedings of Nordic Concrete Research, Vol. 33, 2005, pp. 379-381.
- S. Jacobsen, H. T. Nguyen and F. Melandsø, “Moisture Flow and Frost Exposure of Cement Based Materials,” Proceedings of Nordic Concrete Research, Vol. 33, 2005, pp. 45-47.
- S. Jacobsen, T. A. Hammer and E. J. Sellevold, “Frost testing of High Strength Concrete: Internal Cracking vs. Scaling of OPC and Silica Fume Concretes,” In: S. Lindmark, Ed., “Frost Resistance of Building Materials,” Proceedings of Nordic Research Seminar, Lund, 1996, pp. 49- 68.
- J. R. Welty, C. E. Wicks, R. E. Wilson and G. L. Rorrer, “Fundamentals of Momentum, Heat and Mass Transfer,” 4th Edition, John Wiley & Sons, Inc., New York, 2001.
- C. E. Hagentoft, “Introduction to Building Physics,” Studentlitteratur, Lund, 2001.
- F. P. Incropera and D. P. DeWitt, “Fundamentals of Heat and Mass Transfer,” 5th Edition, John Wiley & Sons, Inc., 2002.
- R. B. Bird, W. E. Stewart and E. N. Lighfoot, “Transport Phenomena,” 2nd Edition, John Wiley& Sons, Inc., 2002.
- I. Lind, “Surface Heat Transfer in Thawing by Forced Air Convection,” Journal of Food Engineering, Vol. 7, 1988, pp. 19-39.
- J. W. Baughn and S. Shimizu, “Heat Transfer Measurements from a Surface with Uniform Heat Flux and an Impinging Jet,” Journal of Heat Transfer, Vol. 111, 1989, pp. 1096-1098.
- A. Sarkar and R. P. Singh, “Spatial Variation of Convective Heat Transfer Coefficient in Air Impingement Applications,” Journal of Food Science, Vol. 68, No. 3, 2003, pp. 910-916.