Latent Heat Storage for Solar Steam Systems

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Wolf-Dieter Steinmann ◽  
Rainer Tamme
Keyword(s):  
Latent Heat ◽  
Power Plants ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage Systems ◽  
Storage System ◽  
Saturation Temperature ◽  
Steam Generation ◽  
Latent Heat Storage ◽  
Research Activities

Solar thermal systems, including direct steam generation in the absorbers, require isothermal energy storage systems. One option to fulfil this requirement is the application of phase change materials (PCMs) to absorb or release energy. The implementation of cost-effective storage systems demands the compensation of the low thermal heat conductivity that is characteristic for the candidate materials for PCM. Solar steam generation for power plants requires latent heat storage systems for a saturation temperature range between 200°C and 320°C. This paper describes the basic concepts investigated and first results of research activities aiming at the demonstration of a storage system using steam provided by parabolic trough collectors.

Numerical and Experimental Analysis of a PCM Thermal Storage System

2014 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda
Keyword(s):  
Latent Heat ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage System ◽  
District Heating ◽  
Thermal Storage ◽  
Working Fluid ◽  
Latent Heat Storage ◽  
Thermal Enhancement ◽  
Charging And Discharging Processes

Phase-change materials (PCM) are particularly promising for thermal storage in energy systems where the working fluid is either characterized by small specific heat or small temperature difference. In these cases, sensible heat storage would involve small energy densities (i.e. energy per unit volume). Latent heat storage would allow one to reduce the volume of storage tanks, but also reduce problems related with thermal stratification. On the other hand, heat transfer in PCMs needs to be enhanced in order to complete the charging and discharging processes in reasonable time. This paper reports the numerical and experimental activity performed by the authors related with the design of latent heat storage systems for district heating applications. Among the various enhancement methods, fins present some technical advantages related with manufacturing and management, which make them suitable for the application in district heating systems. The following aspects are considered in this paper: 1) melting and solidification; 2) modeling approaches and validation; 3) thermal enhancement with circular, radial or Y-shaped fins.

scholarly journals Review on the Integration of Phase Change Materials in Building Envelopes for Passive Latent Heat Storage

2021 ◽  
Vol 11 (19) ◽  
pp. 9305
Author(s):  
Mohamed Sawadogo ◽  
Marie Duquesne ◽  
Rafik Belarbi ◽  
Ameur El Amine Hamami ◽  
Alexandre Godin
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage Systems ◽  
Latent Heat Storage ◽  
Building Envelopes

Latent heat thermal energy storage systems incorporate phase change materials (PCMs) as storage materials. The high energy density of PCMs, their ability to store at nearly constant temperature, and the diversity of available materials make latent heat storage systems particularly competitive technologies for reducing energy consumption in buildings. This work reviews recent experimental and numerical studies on the integration of PCMs in building envelopes for passive energy storage. The results of the different studies show that the use of PCMs can reduce the peak temperature and smooth the thermal load. The integration of PCMs can be done on the entire building envelope (walls, roofs, windows). Despite many advances, some aspects remain to be studied, notably the long-term stability of buildings incorporating PCMs, the issues of moisture and mass transfer, and the consideration of the actual use of the building. Based on this review, we have identified possible contributions to improve the efficiency of passive systems incorporating PCMs. Thus, fatty acids and their eutectic mixtures, combined with natural insulators, such as vegetable fibers, were chosen to make shape-stabilized PCMs composites. These composites can be integrated in buildings as a passive thermal energy storage material.

Thermo-Mechanical Storage of Electricity at Power Plant Scale

2013 ◽  
Author(s):  
Wolf-Dieter Steinmann
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Latent Heat ◽  
Heat Storage ◽  
Storage Systems ◽  
Storage System ◽  
Thermal Storage ◽  
Maximum Temperature ◽  
Latent Heat Storage ◽  
Temperature Heat

The availability of cost effective storage capacity is considered essential for increasing the share of renewables in electricity generation. With the development of solar thermal power plants large thermal storage systems have become commercial in recent years. Various storage concepts are applied, systems using solid storage media are operated at a maximum temperature of 680 °C, other systems using molten salt as storage medium show thermal capacities in the GWh range. Heating these storage systems directly by surplus electricity and using the heat later during the discharge process to operate turbines is not very attractive, since the process is limited by the Carnot efficiency. Alternatively, surplus electricity can be used to transform low temperature heat into high temperature heat which is stored in a thermal storage system during the charging process. During discharge, this heat is used to drive a turbine generating electric energy. Theoretically, this concept allows a roundtrip efficiency of 100%. Various options for the implementation of this storage concept have been suggested, using air or CO2 as working fluids. Recently, DLR has demonstrated the operability of a latent heat storage system connected to a steam circuit at 100 bar. The availability of this latent heat storage technology allows new implementations of the storage concept based on heat transformation. Using a left-running Rankine cycle during the charging process, heat from the environment is used to evaporate steam, which is compressed using the surplus electricity. Superheated steam exiting the compressor flows through the thermal storage system composed of latent heat storage sections and sensible heat storage sections. After throttling, the water enters the evaporator again. During discharging, heat from the storage system is used to evaporate and superheat steam, which drives the turbine. A cascaded implementation of this concept, using ammonia for the low temperature part of the process, while water is used for the high temperature part, reaches a storage efficiency of 70%. The integration of low temperature waste heat sources allows the compensation of losses.

Review of Solar Cooking Using Latent Heat Storage

2014 ◽  
Vol 592-594 ◽  
pp. 1761-1765 ◽  
Author(s):  
Bhagwat Gore ◽  
Madhukar Tandale
Keyword(s):  
Phase Change ◽  
Latent Heat ◽  
Fossil Fuels ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage System ◽  
Melting Process ◽  
Latent Heat Storage ◽  
Endothermic Process ◽  
Increasing Demand

Use of latent heat storage system using Phase Change Materials (PCM) is an effective way of storing thermal energy and has several advantages like high storage density, isothermal nature of the energy storage etc. Solar cooking is one of the solutions to overcome increasing demand of fossil fuels in country like India. However it suffers from problems like low solar intensity, fluctuations during cloudy environment, limited availability (only during few hours of the day), and fluctuations with time. Use of latent heat storage system in solar cooking, can overcome some of the problems listed above. In this paper, efforts were made to gather the information on previous works on solar cooking system using PCM, use of Phase Change Materials (PCMs) for evening / night cooking and conceptual design of solar cooker using PCM. This review will be important for further research in this field. Heat storage system enables cooking food during cloudy sky or in the evening. Hence, solar cooker with PCM storage will increase the utility and reliability of the solar cookers. As the source temperature raises, the chemical bonds within the PCM breaks which changes phase from solid to liquid. The phase change is a heat-seeking (endothermic) process and therefore, the PCM absorbs heat on melting. Upon storing heat in the storage material, the material begins to melt when the phase change temperature is reached. The temperature then stays constant until the melting process is completed. The solar energy stored during day time can be used directly for cooking or can be stored in PCM and used during night/evening time.

scholarly journals Experimental Analysis of the Latent Heat Storage System (LHS) Using Paraffin Wax as Phase Change Material

2021 ◽  
Vol 9 (VIII) ◽  
pp. 234-241
Author(s):  
Mr. Omkar Jadhav
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Storage System ◽  
High Energy ◽  
Paraffin Wax ◽  
Latent Heat Storage ◽  
Change Material

An experimental study using paraffin wax as a phase change material (PCM) was performed to analyse thermal physiognomies on the latent heat storage system (LHS). The use of phase change materials through latent heat storage is an unusual approach to maintaining thermal energy. There is the advantage of considerably high energy storage and the uniform temperature of the storage process. Tube & shell type heat exchanger (HE) has been used in this experimentation. Water circulates in tubes and around the tube’s paraffin wax as phase change material is filled. The focus is on heating (charging) and cooling (discharging) of PCM (paraffin wax), which is the melting and solidifying of paraffin wax. The temperature distribution in paraffin is studied consistent with the various flow rates of the warmth transfer fluid.

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