Dynamic model of a small scale concentrating solar cooker with rock bed heat storage

Authors

  • Karidewa Nyeinga Makerere University
  • Ole J Nydal Norwegian University of Science & Technology
  • Denis Okello Makerere University
  • Eldad J.K.B. Banda Makerere University

DOI:

https://doi.org/10.17159/2413-3051/2016/v27i1a1563

Keywords:

rock bed, heat storage, solar cooker, energy equation, mass balance, momentum equation, pressure equation, staggered grid

Abstract

This study presents a dynamic model for a concentrating solar energy collector with an integrated rock bed heat storage system. The model is based on numerical integration of a set of conservation equations for mass, momentum and energy of the heat carrier, the rock pebbles and the walls. The heat carrier is compressible air. Numerical solutions are implemented based on implicit time integration without iterations. Stability problems at large time steps do not occur but the accuracy is reduced. The model predicts pressure, velocity, density and temperatures of the fluid, rock bed and wall in time and along the bed. The model is validated with experimental results in a laboratory setting on temperature profiles during charging and discharging of rock bed heat storage. The intention is that the model shall serve as a computational tool for upscaling of air based concentrating solar energy systems with rock bed heat storage units.

Downloads

Download data is not yet available.

Metrics

Metrics Loading ...

References

Lovseth J. Small, multi-purpose concentrating solar energy systems for villages. Proceedings ISES 1997 Solar World Congress, 7:108-177, 1997.

Heetkamp van den R.R.J. The development of small solar concentrating systems with heat storage for rural food preparation. Physica Scripta T97, pages 99-106, 2002.

Chikukwa A. Modelling of a Solar Stove: Small concentrating system with a heat storage. PhD thesis, Norwegian University of Science & Technology, 2007.

Schumann T.E.W. A liquid flowing through a porous prism. J. Franklin Inst., 208:405, 1929.

Okello D. Rock bed thermal energy storage for solar cooking application – potential for solar cooking in Uganda. PhD thesis, Makerere University, 2012.

Madessa H.B., Lovesth J., and Nydal O.J. Experimental investigation on rock bed for high temperature solar thermal storage. In Renewable Energy Shaping Our Future - Proceedings of the ISES Solar World Congress 2009. Johannesburg, South Africa, 11-14 October, 2009.

Versteeg H.K. and Malalasekera W. An Introduction to Computational Fluid Dynamics. Addis on Wesley Longman Limited, 1995.

Dufie J.A. and Beckman W.A. Solar Engineering of Thermal Processes. John Wiley and Sons,Inc. 2nd edition, 2006.

Anton Meir, Christian Winkler, and Daniel Wuillemin. Experiment for modeling high temperature rock bed storage. Solar Energy Materials, 24:255-264, 1991.

Elisabeth Schroder, Andreas Class, and Lambert Krebs. Measurements of heat transfer between particles and gas in packed beds at low to medium Reynolds numbers. Experimental Thermal and Fluid Science, 30:545-558, 2006.

Bhavsar V.C and Balakrishna A. R. Pebble bed-oil thermal energy storage for solar thermo-electric power systems. International Journal of Energy Research, 14:233-240, 1990.

Slavin A.J., Arcas V., Greenhalgh C.A., Irvin E.R., and Marshall D.B. Theoretical model for the thermal conductivity of a packed bed of solid spheroids in the presence of a static gas, with no adjustable parameters except at low pressure and temperature. International Journal of Heat and Mass Transfer, 45:4151-4161, 2002.

Barrie W. Jones and Mahyar Golshekan. Destratification and other properties of a packed bed heat store. J. Heat and Mass Transfer, 32:351-359, 1989.

Downloads

Published

2016-03-23

How to Cite

Nyeinga, K., Nydal, O. J., Okello, D., & Banda, E. J. (2016). Dynamic model of a small scale concentrating solar cooker with rock bed heat storage. Journal of Energy in Southern Africa, 27(1), 20–27. https://doi.org/10.17159/2413-3051/2016/v27i1a1563