Thermocline degradation in a packed bed thermal storage tank
A method under consideration for storage and retrieval of heat energy in central solar receiver power plants involves the use of packed beds through which a fluid can be made to flow. Heat energy is stored in the solid portions of the bed and then reclaimed at a later time by a heat transfer mechanism when colder fluid is passed through the tank. Of crucial importance to this process is the ability to maintain a sharp temperature difference (thermocline) between the hot and cold ends of the bed during long storage periods when no new fluid enters the tank. The degradation of this thermocline over a period of time is described here by a coupled pair of parabolic partial differential equations for the fluid and solid temperatures of the bed. The time-dependent, quasi-one-dimensional model is solved analytically and includes the effects of finite tank length, thermal conduction in the direction parallel to the tank walls, and heat transfer between the fluid and solid components of the bed. Two types of problems are considered. The case of a perfectly insulated tank is solved by a Fourier method of lines (separation of variables) approach, while the solution for the imperfectly insulated case is obtained by a more general transform technique. The analysis, which gives the time evolution of the fluid and solid temperature profiles, is illustrated by specific examples and important conclusions are drawn from the results.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5695070
- Report Number(s):
- SAND-77-8032; CONF-771106-1
- Resource Relation:
- Conference: 30. annual meeting of the division of fluid dynamics of the American Physical Society, Bethlehem, PA, USA, 21 Nov 1977
- Country of Publication:
- United States
- Language:
- English
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Analytical solution for the multidimensional degradation of a packed bed thermocline
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Related Subjects
THERMAL ENERGY STORAGE EQUIPMENT
MATHEMATICAL MODELS
TEMPERATURE DISTRIBUTION
DIFFERENTIAL EQUATIONS
FLUID FLOW
HEAT TRANSFER FLUIDS
PACKED BED
THERMAL INSULATION
TOWER FOCUS POWER PLANTS
EQUATIONS
EQUIPMENT
FLUIDS
POWER PLANTS
SOLAR POWER PLANTS
SOLAR THERMAL POWER PLANTS
THERMAL POWER PLANTS
142000* - Solar Energy- Heat Storage- (1980-)