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HESs for Carbon-Free District Heating and Cooling
Published in Yatish T. Shah, Hybrid Energy Systems, 2021
High temperature heat is already stored on sites using regenerator materials and in a steam accumulator. The accumulator matches steady production of steam from boilers to the short discharge needs of the vacuum processes. If more heat is to be recovered then the thermal capacities of the ceramic regenerators or the steam accumulator could be used to balance supply and demand of waste heat, although modifications will be needed to make such connections. If flue gas heat is recovered for generating steam then using existing steam storage facilities may be sufficient. Medium to low temperature heat could be stored using hot water tanks which can be linked to DH networks. If the water in the store is circulated in the network then this prevents temperature losses through heat exchangers. However, the water quality needs to be sufficiently high and the temperatures and pressures of operation need to be compatible with the network. In the case of Sheffield’s DH, the store would need to operate between 70°C and 110°C. For low-temperature waste heat, underground TES could be used and would give potentially a high heat capacity at low cost. Storing the cooling water is an option, but low temperatures mean a large volume of storage would be needed and this increases expense. If electricity is needed to run a heat pump and upgrade this heat at the time of use then this may be costly if it is needed at peak demand times. Any heat recovery project needs to be evaluated, not just in economic terms but also in terms of its environmental impacts. This can help industry meet environmental objectives [38,95–101].
Modular Systems for Energy Usage in District Heating
Published in Yatish T. Shah, Modular Systems for Energy Usage Management, 2020
High-temperature heat is already stored on sites using regenerator materials and in a steam accumulator. The accumulator matches steady production of steam from boilers to the short discharge needs of the vacuum processes. If more heat is to be recovered then the thermal capacities of the ceramic regenerators or the steam accumulator could be used to balance supply and demand of waste heat, although modifications will be needed to make such connections. If flue gas heat is recovered for generating steam then using existing steam storage facilities may be sufficient. Medium- to low-temperature heat could be stored using hot water tanks which can be linked to DH networks. If the water in the store is circulated in the network then this prevents temperatures losses through heat exchangers. However, the water quality needs to be sufficiently high and the temperatures and pressures of operation need to be compatible with the network. In the case of Sheffield’s DH, the store would need to operate between 70°C and 110°C. For low-temperature waste heat, underground TES could be used and would give potentially a high heat capacity at low cost. Storing the cooling water is an option, but low temperatures mean a large volume of storage would be needed, and this increases expense. Any heat recovery project needs be evaluated, not only in economic terms but also in terms of its environmental impacts. This can help industry meet environmental objectives [71–78].
Solar Collectors and Solar Thermal Energy Systems
Published in Radian Belu, Fundamentals and Source Characteristics of Renewable Energy Systems, 2019
There two major types of the thermal energy storage systems: sensible heat and latent heat types. The term sensible heat describes the heat which is absorbed or released by a material as a result of a change in temperature, whereupon the material does not undergo a change of aggregate state. When storing latent heat, the property of materials to absorb or release heat energy during a phase change is used. Latent heat storage systems therefore use a phase change material (PCM) as storage medium. In principle there are three possible phase changes: solid—solid, solid—liquid, and liquid—vapor thermal energy systems. The phase change solid—solid and liquid—vapor types are seldom used in practical applications. In the present days, the latent heat storage systems, the phase change solid—liquid plays an important role in the TES applications. Both, sensible heat and latent heat are discussed in a later chapter. The current thermal energy storage types can be divided into four main groups: (1) thermal energy storage systems for sensible heat, further divided into: (a) indirect storage systems, and (b) direct storage systems; (2) latent heat thermal energy storage; (3) steam accumulator; and (4) thermo-chemical energy storage system. There are four indirect storage concepts, introduced here, that are often employed in solar thermal applications: 2-tank molten salt indirect thermal energy storage, packed-bed thermal energy storage (regenerator); sand thermal energy storage, and concrete heat storage.
Variable and Assured Peak Electricity Production from Base-Load Light-Water Reactors with Heat Storage and Auxiliary Combustible Fuels
Published in Nuclear Technology, 2019
A steam accumulator is a pressure vessel nearly full of water that is heated to its saturation temperature by steam injection. The heat is stored as high-temperature high-pressure water. When steam is needed, valves open and some of the water is flashed to steam that is sent to a turbine or feedwater heaters generating electricity while the remainder of the water decreases in temperature. This system has a faster response than any other heat storage system but the steam from any one bank of accumulators decreases in pressure and temperature with time. Multiple accumulators can be arranged to provide a steady flow of steam at several different pressures.
Energy efficiency in steam using industries in Greece
Published in International Journal of Sustainable Energy, 2020
Ifigenia Farrou, Andreas Androutsopoulos, Aristotelis Botzios-Valaskakis, Georges Goumas, Charilaos Andreosatos, Loukas Gavriil, Christoforos Perakis
A steam accumulator is a heat storage device. It stores energy in the form of vapour to respond to the variability of heat demand. The purpose of a steam accumulator is to release steam when the demand is greater than the boiler's ability to supply at that time, and to accept steam when demand is low.