Enhancement of the Efficiency of an Underground Thermal Energy Storage System (Laghouat, Algeria)

Page:

135-142

DOI:

https://doi.org/10.18280/ijht.310118

OPEN ACCESS

Abstract:

Energy is a vital input for social and economic development. As a result of the generalization of agricultural, industrial and domestic activities the demand for energy has increased remarkably, especially in emergent countries. This has meant rapid grower in the level of greenhouse gas emissions and the increase in fuel prices, which are the main driving forces behind efforts to utilize renewable energy sources more effectively and develop the research of heat storage systems. The objective of this paper is to investigate the possibility of using a continuous solid medium, composed mainly of an unsaturated sandy soil, which is the case in many desert areas in the world, where the solar energy is abundant, for long or short term like Underground Thermal Energy Storage System (UTESS) using a simple configuration and local means of low cost. Despite all attempts made by researchers and the continuous progress brought about, UTESS are still dependent mainly on the geological nature of the soil and they require enormous means for their construction in some cases with non usual cooling and heating systems. As a matter of fact, solar heat is characterized by its intermittency, in order to overcome this disadvantage, similar techniques can be useful to store thermal energy for later use. A mathematical model based on the heat conduction equation in two dimensional cylindrical coordinates is adopted to describe the heat transfer between a buried pipe and the storage medium (soil). Using a new analytical approach, a steady state solution of this model is presented, which consists of an exact solution composed of the sum of two functions. The approach is then used to determine the overall heat coefficient, the amount of heat stored, the amount of heat recovered and the heat storage efficiency. Some original conclusions and suggestions are given.

Keywords:

*efficiency, exact solution, heat conduction, underground heat storage*

References

[1] Dinçer, I., Rosen, M.A. (2011) Thermal Energy Storage: Systems and Applications. Second Edition, John Wiley & Sons, Ltd

[2] Hazamil, M., Koolil, S., Lazâarl, M., Farhatl, A., Belghith, A. 2 Energy and exergy efficiency of a daily heat storage unit for buildings heating (2009) Revue des Energies Renouvelables, 12 (2), pp. 185-200.

[3] Gauthier, C., Lacroix, M., Bernier, H. Numerical simulation of soil heat exchanger-storage systems for greenhouses (1997) Solar Energy, 60 (6), pp. 333-346. doi: 10.1016/S0038-092X(97)00022-4

[4] Adinberg, R., Epstein, M. Conception and design of a thermal energy storage system (2007) Proceedings of the Heat Transfer, Thermal Engineering and Environment (HTE'07), pp. 141-145. Athens, Greece

[5] Sukhatme, S.P. (1991) Solar Energy, Principles of Thermal Collection and Storage, Tata McGraw-Hill Publishing Company Limited, New Delhi. Solar engineering book with emphasis on collection and storage of thermal energy

[6] Rosen, M.A. The exergy of stratified thermal energy storages (2001) Solar Energy, 71 (3), pp. 173-185. doi: 10.1016/S0038-092X(01)00036-6

[7] Michael, F. (2003) Hordeski, New Technologies for Energy Efficiency The Fairmont Press

[8] MacPhee, D., Dincer, I. Performance assessment of some ice TES systems (2009) International Journal of Thermal Sciences, 48 (12), pp. 2288-2299. doi: 10.1016/j.ijthermalsci.2009.03.012

[9] Vasiliev, L.L. Heat pipes for ground heating and cooling (1988) Heat Recovery Systems and CHP, 8 (2), pp. 125-139. doi: 10.1016/0890-4332(88)90005-1

[10] Dempsey, B.J. A mathematical model for predicting coupled heat and water movement in unsaturated soil (1978) International Journal for Numerical and Analytical Methods in Geomechanics, 2 (1), pp. 19-34. doi: 10.1002/nag.1610020103

[11] Carslaw, H.S., Jaeger, J.C. (1946) Conduction of Heat in Solids. Claremore Press: Oxford

[12] Claesson, J., Dunand, A. (1983) Heat Extraction from the Ground by Horizontal Pipes, a Mathematical Analysis. Swedish Council for Building Research: Stockholm

[13] Thomas, H.R. A nonlinear analysis of two‐dimensional heat and moisture transfer in partly saturated soil (1988) International Journal for Numerical and Analytical Methods in Geomechanics, 12 (1), pp. 31-44. doi: 10.1002/nag.1610120103

[14] Benchatti, A., Medjelled, A., Thomas Jr., J.R., Bounif, A., Bouhadef, K. Analytical solution of steady state 2D heat conduction equation (case of horizentale pipe buried in an unsaturated soil) (2006) International Journal of Heat and Technology, 24 (1), pp. 25-31. http://www.iieta.org/Journals/H%26TECH/CURRENT%20ISSUE

[15] Benchatti, A., Medjelled, A., Bouhadef, K. Analytical solution of unsteady state 2D heat conduction equation (case of horizentale pipe buried in an unsaturated soil) (2006) International Journal of Heat and Technology, 24 (2), pp. 95-102. http://www.iieta.org/Journals/H%26TECH/CURRENT%20ISSUE

[16] Ercan Ataer, O. Storage of thermal energy, in energy storage systems, [Ed. Yalcin Abdullah Gogus] (2006) Encyclopedia of Life Support Systems (EOLSS), Developed under the Auspices of the UNESCO. Eolss Publishers, Oxford, UK

[17] de Vries, Daniel A. HEAT TRANSFER IN SOILS. (1975) Semin on Heat and Mass Transfer in the Environ of Veg, Heat and Mass Transfer in the Biosphere, (Pt 1), pp. 5-28.

[18] Medjelled, A., Benchatti, A., Bouni, A. Experimental model for the studyof heat transfer in unsaturateed soil: Case of underground thermal storage (2008) International Journal of Heat and Technology, 26 (1), pp. 97-104. http://www.iieta.org/Journals/H%26TECH/CURRENT%20ISSUE

[19] Ribeiro, P.F., Crow, M.L. (2001) PROCEEDINGS of the IEEE, 89 (12).

[20] Dincer, I., Dost, S. A perspective on thermal energy storage systems for solar energy applications (1996) International Journal of Energy Research, 20 (6), pp. 547-557. http://onlinelibrary.wiley.com.ezproxy3.lhl.uab.edu/journal/10.1002/(ISSN)1099-114X doi: 10.1002/(SICI)1099-114X(199606)20:6<547::AID-ER173>3.0.CO;2-S

[21] Haller, M.Y., Yazdanshenas, E., Andersen, E., Bales, C., Streicher, W., Furbo, S. A method to determine stratification efficiency of thermal energy storage processes independently from storage heat losses (2010) Solar Energy, 84 (6), pp. 997-1007. doi: 10.1016/j.solener.2010.03.009

[22] Riahi, M. Efficiency of heat storage in solar energy systems (1993) Energy Conversion and Management, 34 (8), pp. 677-685. doi: 10.1016/0196-8904(93)90102-G