Latent Heat Storage Systems for Solar Thermal Power Plants and Process Heat Applications

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Wolf-Dieter Steinmann ◽  
Doerte Laing ◽  
Rainer Tamme
Keyword(s):  
Latent Heat ◽  
Power Plants ◽  
Heat Storage ◽  
Storage Systems ◽  
Thermal Power ◽  
Solar Thermal ◽  
Thermal Power Plants ◽  
Latent Heat Storage ◽  
Solar Thermal Power ◽  
Process Heat

Solar thermal systems using absorber evaporating steam directly require isothermal energy storage. The application of latent heat storage systems is an option to fulfill this demand. This concept has been demonstrated mainly for low temperature heating and refrigeration applications, the experience for the power level and temperature range characteristic of solar process heat and solar thermal power plants is limited. Cost effective implementation of the latent heat storage concept demands low cost phase change materials (PCMs). These PCMs usually show low thermal conductivity limiting the power density during the charging/discharging process. This paper describes various approaches, which have been investigated to overcome these limitations. Based on fundamental PCM-research and laboratory-scale experiments, the sandwich concept has been identified to show the highest potential. The sandwich concept has been demonstrated successfully for three different storage units ranging from 2 kW to 100 kW at melting temperatures of 145°C and 225°C.

Methodology for optimized operation strategies of solar thermal power plants with integrated heat storage

Solar Energy ◽  
2011 ◽  
Vol 85 (4) ◽  
pp. 653-659 ◽  
Author(s):  
Michael Wittmann ◽  
Markus Eck ◽  
Robert Pitz-Paal ◽  
Hans Müller-Steinhagen
Keyword(s):  
Power Plants ◽  
Heat Storage ◽  
Thermal Power ◽  
Solar Thermal ◽  
Thermal Power Plants ◽  
Solar Thermal Power

PCM-Graphite Latent Heat Storage Systems for Industrial Process Heat Recovery

2010 ◽  
Vol 74 ◽  
pp. 259-265
Author(s):  
Rainer Schmitt ◽  
Oswin Öttinger ◽  
Wolf Dieter Steinmann ◽  
Maike Johnson
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Latent Heat ◽  
Alternative Energy ◽  
Heat Storage ◽  
Storage Systems ◽  
Thermal Power ◽  
Latent Heat Storage ◽  
Graphite Composite ◽  
Process Heat

Increasing energy prices and shortage of fossil fuels lead to a growing interest in alternative energy sources. In combination with energy storage systems the generation of solar process heat can be provided independent from the weather leading for example to a cost efficient stabilization of power output. For this application latent heat storage units with phase change materials (PCMs) can be designed to store solar process heat within a narrow temperature interval utilizing the high storage density of the different PCMs. This is achieved using the latent heat of melting in the melting / solidification process, or the latent heat of re-crystallization in a solid / solid phase transition. However, this advantage can only be used in technical applications if the heat transfer in the PCM is sufficiently high. As most pure PCMs exhibit a low thermal conductivity (about 1 W/(m•K) or less), methods to improve heat transfer in PCMs have been under investigation for decades. The heat transfer in a PCM can be increased by addition of highly thermal conductive materials. Due to its superior properties - high thermal conductivity, good processability, and chemical inertness - graphite has distinct advantages for this purpose. Depending on the requirements of the respective application, various routes to combine PCM and graphite are used. For example, besides the fabrication of PCM/graphite composite materials, the increase of heat exchanger surface by highly thermal conductive graphite plates is a favorable method for large scale applications, in particular. Effective thermal conductivities up to 30 W/(m•K) have been realized. This paper gives an overview of actual and potential applications of PCM/graphite heat storage systems focusing on storage of solar heat for high temperature applications such as process heat generation and solar thermal power plants.

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