PDF Publication Title:
Text from PDF Page: 013
Annual Review of Heat Transfer, Vol. 15, p.131-177 https://doi.org/10.1615/AnnualRevHeatTransfer.2012004651 It only provides a limited operation range between 0 oC (freezing) and 100 oC (boiling) It is corrosive It has high vapor pressures (p > 5 bar) at temperatures > 155 oC The vapor pressure can be reduced when mixtures of water with other chemicals are applied; e.g., a mixture of 50 % H2O and 50 % NaOH can be used up to 140 oC without a pressure vessel. Storage tanks for hot water are used in industry and dwellings. They come in sizes of 0.1 m3 (domestic hot water storage) to 12000 m3 (solar assisted district heating). Another development is the “solar combination store” of about 0.5 m3 which serve for both domestic hot water supply and house heating. Water is commonly used also in large thermal stores, both as storage medium and heat transfer fluid. In large stores (e.g., seasonal stores for solar energy) the storage capacity can be turned over only once or — at the most — three times a year. Such a small energy turnover makes the stored heat expensive unless the storage container is inexpensive. A technical/economical boundary for steel tanks is a size of around 100 000 m3. For ground containers, the waterproof liner may create problems (e.g., tightness after welding, perforation by stones): polymer and stainless steel liners are used. These large containers are built of concrete and they are fully or partly buried in the ground. Their capacity is around 80 kWh/m3. In summer, hot water is fed to the water layers on top and cold water withdrawn from the bottom, in winter, hot water is withdrawn from the top layers and cold water re-fed at the bottom. In so-called ground stores low temperature heat is stored in soil or pebbles. The storage medium in such cases is a mixture of water and solid particles. Density and specific heat capacity of these mixtures can be obtained from the mixing laws. The thermal conductivity depends strongly on the composition of the mixture. Although some mathematical equations exist in the literature, reliable data for λ depend on measurements. Heat is usually exchanged with the ground by tubes containing a circulating carrier fluid, mostly water. These tubes may be placed close to the surface (0.5 – 1 m below) in a meandering arrangement or spirally wound in horizontal ditches. For large stores (more than 10000 m3 water equivalent storage capacity), vertical holes are drilled for the heat exchanger tubes. In some areas, geology allows for a so-called aquifer store. This requires a permeable layer of soil (pebbles or sand) enclosed between horizontal layers of impermeable material (clay). Under such advantageous conditions, two fountains can be drilled some distance apart from each other and hot water can be inserted in summer and withdrawn in winter. Problems can arise from minerals dissolving in the water and precipitating on tubes and heat exchangers. So-called man-made aquifers are built in sizes of 10000 m3; the ground excavations are filled with pebbles and water and sealed by plastic sheets (Tamme 2009). In all cases where mixtures of water and solid material are used for heat storage, the storage volume has to be larger than in the case of pure water.Table 3 gives some approximate data. Table 3: Storage volume of different storage media compared to pure water for 1 m3 water equivalent and 60 kWh capacity at Δ T = 50 K Storage media Hot water storage Pebble – water storage Aquifer storage Borehole storage Storage volume 1 m3 1.3 – 2 m3 2 – 3 m3 4 – 5 m3 Large scale solar thermal storage in water is also possible in solar ponds. These ponds act both as solar collector and as storage. In this concept the water itself is used as an insulator.PDF Image | Annual Review of Heat Transfer
PDF Search Title:
Annual Review of Heat TransferOriginal File Name Searched:
2012_Thermal_Energy_Storage_Materials_and_Systems.pdfDIY PDF Search: Google It | Yahoo | Bing
Turbine and System Plans CAD CAM: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. More Info
Waste Heat Power Technology: Organic Rankine Cycle uses waste heat to make electricity, shaft horsepower and cooling. More Info
All Turbine and System Products: Infinity Turbine ORD systems, turbine generator sets, build plans and more to use your waste heat from 30C to 100C. More Info
CO2 Phase Change Demonstrator: CO2 goes supercritical at 30 C. This is a experimental platform which you can use to demonstrate phase change with low heat. Includes integration area for small CO2 turbine, static generator, and more. This can also be used for a GTL Gas to Liquids experimental platform. More Info
Introducing the Infinity Turbine Products Infinity Turbine develops and builds systems for making power from waste heat. It also is working on innovative strategies for storing, making, and deploying energy. More Info
Need Strategy? Use our Consulting and analyst services Infinity Turbine LLC is pleased to announce its consulting and analyst services. We have worked in the renewable energy industry as a researcher, developing sales and markets, along with may inventions and innovations. More Info
Made in USA with Global Energy Millennial Web Engine These pages were made with the Global Energy Web PDF Engine using Filemaker (Claris) software.
Sand Battery Sand and Paraffin for TES Thermo Energy Storage More Info
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |