Effect of stratification on energy and exergy capacities in thermal storage systems

Rosen, Marc A.; Tang, Raymond; Dinçer, İbrahim

doi:10.1002/er.960

Cited by 102 publications

(29 citation statements)

References 13 publications

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“…Kleinbach, Beckman, and Klein (1993) and Mather, Hollands, and Wright (2002) demonstrate the importance of the number of nodes with regard to accuracy of the model and more specifically the rate of stratification. This stratification plays an important role in the efficiency of the tank and as a consequence the total system (Rosen, Tang, and Dincer 2004).…”

Section: Dhw and Storage Tankmentioning

confidence: 99%

Rule-based demand-side management of domestic hot water production with heat pumps in zero energy neighbourhoods

Coninck

Bætens

Sælens

et al. 2013

Journal of Building Performance Simulation

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Grid saturation has been reported in electricity distribution systems with a high penetration of photovoltaic (PV) systems. This saturation is often caused by overvoltage and results in curtailing or shutting down of the PV inverters, leading to a loss of renewable electricity generation. The presented work assesses the potential of rule-based demand-side management (DSM) applied to domestic hot water (DHW) production with heat pumps in dwellings for reducing the non-renewable energy use of the neighbourhood. The studied case consists of 33 single-family dwellings connected to a single phase distribution grid in a moderate European climate. Each dwelling is designed as a net-zero energy building by adequate design of a heat pump and PV system. A detailed dynamic simulation model is implemented by use of a cross-domain Modelica library for integrated district energy assessment. The user behaviour is obtained from a stochastic model based on Markov chains and survival analysis. Different rule-based DSM control strategies are applied to the individual dwelling's DHW systems. The results show that for balancing the PV production, active thermal energy storage in the DHW storage tanks is very promising. Even with very basic control algorithms and small storage tanks of 0.3 m 3 , curtailing losses can be reduced by 74%. This represents a net energy saving on a neighbourhood level of 3.4%.

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Section: Dhw and Storage Tankmentioning

confidence: 99%

Rule-based demand-side management of domestic hot water production with heat pumps in zero energy neighbourhoods

Coninck

Bætens

Sælens

et al. 2013

Journal of Building Performance Simulation

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show abstract

“…For example, Rosen et al [8] consider the effect of stratification (defined as the division of water into layers of different temperature inside the TES) on energy and exergy capacities in thermal storage systems and found that use of stratification in TES design increases the exergy storage capacity of the TES and exergy analysis should be applied in the analysis and comparison of stratified TES. Bedouani et al [9,10] modelled and experimentally validated a central electric thermal storage system for residential use, and performed a techno-economic study of the system.…”

Section: Introductionmentioning

confidence: 98%

Solid oxide fuel cell micro combined heat and power system operating strategy: Options for provision of residential space and water heating

Giarola

Aguiar

Croxford

et al. 2007

Journal of Power Sources

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“…During the static mode of operation, velocity and temperature boundary layers form along the lateral wall of the water tank as a result of the heat transfer from the fluid in the tank to the environment, thus inducing thermal stratification in the tank. This stratification significantly affects thermal energy storage capacity and even system efficiency [2].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of the influences of different water tank shapes on thermal energy storage capacity and thermal stratification

et al. 2016

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a b s t r a c tThe influences of different water tank shapes on thermal energy storage capacity and thermal stratification in the static mode of operation is investigated in this study under laminar natural convection. A new experimental apparatus is built, and a numerical model is developed to simulate the flow and heat transfer in the water tank. Computational results agree with the experimental data. Among the 10 different water tank shapes studied, the sphere and barrel water tanks are ideal for thermal energy storage capacity, whereas the cylinder water tank is the least favorable. The thermal energy storage capacity is closely related to the surface area of the water tank. According to the characteristics of the velocity and temperature fields, these shapes can be divided into three categories: shapes with sharp corners, those with hemispheres, and those with horizontal plane surface. Shapes with sharp corners have the highest degree of thermal stratification, whereas the shapes with horizontal plane surface possess the lowest. That of the shapes with hemispheres lies in between these two degrees. The thermal stratification of different shapes is determined by the flow at the bottom of the water tank and the heat transfer from the fluid to the environment.Thermal energy storage in water tanks is important in many engineering fields, such as in the storage systems of supercritical compressed air, solar heating systems, and nuclear reactors. The operation process of the water tank can be divided into the dynamic mode of operation and the static mode of operation. The dynamic mode of operation refers to its operation when thermal energy from the tank is being used, i.e., when the discharging/ charging process is taking place. The static mode of operation refers to its thermal behavior when the water in the tank is not being used, i.e., when there is not water flowing in/from the tank [1]. The static mode of operation is also called the cooling process in some literature, because the thermal behavior in the static mode of operation is caused by a natural cooling process (i.e. a passive and not an active one) owing to heat losses to the environment. During the static mode of operation, velocity and temperature boundary layers form along the lateral wall of the water tank as a result of the heat transfer from the fluid in the tank to the environment, thus inducing thermal stratification in the tank. This stratification significantly affects thermal energy storage capacity and even system efficiency [2].Many researchers are interested in this topic. Rodríguez et al.[3] studied the transient cooling of a fluid that is initially at rest inside a vertical cylinder and is subject to heat loss through the walls. A correlation for the Nu number was obtained, and a global thermodynamic model was successfully established. He et al. [4] investigated natural convection heat transfer and flow in a vertical cylinder with two ends at different temperatures. The variation patterns of Nu versus Ra are consistent with the resul...

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Effect of stratification on energy and exergy capacities in thermal storage systems

Cited by 102 publications

References 13 publications

Rule-based demand-side management of domestic hot water production with heat pumps in zero energy neighbourhoods

Rule-based demand-side management of domestic hot water production with heat pumps in zero energy neighbourhoods

Solid oxide fuel cell micro combined heat and power system operating strategy: Options for provision of residential space and water heating

Comparative study of the influences of different water tank shapes on thermal energy storage capacity and thermal stratification

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