Appropriate Thermodynamic Performance Measures for Closed Systems for Thermal Energy Storage

1992 ◽  
Vol 114 (2) ◽  
pp. 100-105 ◽  
Author(s):  
M. A. Rosen
Keyword(s):  
Energy Storage ◽  
Performance Measures ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Exergy Efficiency ◽  
Storage Process ◽  
Common Definition ◽  
Energy And Exergy ◽  
Thermodynamic Performance ◽  
Closed Systems

Several definitions of energy and exergy efficiency for closed systems for thermal energy storage (TES) are developed and discussed. A simple model is utilized in which heat quantities are transferred at specified temperatures to and from a TES. Efficiency definitions are considered for the overall storage process and for the three component periods which comprise a complete storage process (charging, storing, and discharging). It is found that (1) appropriate forms for both energy and exergy efficiency definitions depend on which quantities are considered to be products and inputs; (2) different efficiency definitions are appropriate in different applications; (3) comparisons of different TES systems can only yield logical results it they are based on a common definition, regardless of whether energy or exergy quantities are considered; and (4) exergy efficiencies are generally more meaningful and illuminating than energy efficiencies for evaluating and comparing TES systems. A realistic, but simplified, illustrative example is presented. The efficiency definitions should prove useful in the development of valid and generally accepted standards for the evaluation and comparison of different TES systems.

Thermodynamic Performance of Ice Thermal Energy Storage Systems

2000 ◽  
Vol 122 (4) ◽  
pp. 205-211 ◽  
Author(s):  
Marc A. Rosen ◽  
Ibrahim Dincer ◽  
Norman Pedinelli
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Analysis ◽  
Average Energy ◽  
Cooling Capacity ◽  
Energy And Exergy ◽  
Thermodynamic Performance ◽  
And Performance ◽  
Thermal Energy Storage Systems

The thermodynamic performance of an encapsulated ice thermal energy storage (ITES) system for cooling capacity is assessed using exergy and energy analyses. A full cycle, with charging, storing, and discharging stages, is considered. The results demonstrate how exergy analysis provides a more realistic and meaningful assessment than the more conventional energy analysis of the efficiency and performance of an ITES system. The overall energy and exergy efficiencies are 99.5 and 50.9 percent, respectively. The average exergy efficiencies for the charging, discharging, and storing periods are 86, 60, and over 99 percent, respectively, while the average energy efficiency for each of these periods exceeds 99 percent. These results indicate that energy analysis leads to misleadingly optimistic statements of ITES efficiency. The results should prove useful to engineers and designers seeking to improve and optimize ITES systems. [S0195-0738(00)00904-3]

scholarly journals Energy and Exergy Analysis of Sensible Thermal Energy Storage—Hot Water Tank for a Large CHP Plant in Poland

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4842 ◽  
Author(s):  
Ryszard Zwierzchowski ◽  
Marcin Wołowicz
Keyword(s):  
Energy Storage ◽  
Ambient Temperature ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Exergy Analysis ◽  
Hot Water ◽  
Water Tank ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis

The paper contains a simplified energy and exergy analysis of pumps and pipelines system integrated with Thermal Energy Storage (TES). The analysis was performed for a combined heat and power plant (CHP) supplying heat to the District Heating System (DHS). The energy and exergy efficiency for the Block Part of the Siekierki CHP Plant in Warsaw was estimated. CHP Plant Siekierki is the largest CHP plant in Poland and the second largest in Europe. The energy and exergy analysis was executed for the three different values of ambient temperature. It is according to operation of the plant in different seasons: winter season (the lowest ambient temperature Tex = −20 °C, i.e., design point conditions), the intermediate season (average ambient temperature Tex = 1 °C), and summer (average ambient temperature Tex = 15 °C). The presented results of the analysis make it possible to identify the places of the greatest exergy destruction in the pumps and pipelines system with TES, and thus give the opportunity to take necessary improvement actions. Detailed results of the energy-exergy analysis show that both the energy consumption and the rate of exergy destruction in relation to the operation of the pumps and pipelines system of the CHP plant with TES for the tank charging and discharging processes are low.

New bounds for the thermal energy storage process with stationary input

1982 ◽  
Vol 19 (04) ◽  
pp. 894-899 ◽  
Author(s):  
J. Haslett
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Systems ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Storage Process

The process {Xn }, defined by Xn + 1 = max{Yn + 1 + αßX n, ßX n}, with αand ß in [0, 1) and {Yn } stationary, arises in studies of solar thermal energy systems. Bounds for the stationary mean EX are given, which are more general and in some cases tighter, than those previously available.

A thermal energy storage process with controlled input

1982 ◽  
Vol 14 (02) ◽  
pp. 257-271 ◽  
Author(s):  
D. J. Daley ◽  
J. Haslett
Keyword(s):  
Stochastic Process ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Queueing Theory ◽  
Random Variable ◽  
Stationary Sequence ◽  
Storage Process ◽  
Storage Model ◽  
Special Cases

The stochastic process {Xn } satisfying Xn +1 = max{Yn +1 + αβ Xn , βXn } where {Yn } is a stationary sequence of non-negative random variables and , 0<β <1, can be regarded as a simple thermal energy storage model with controlled input. Attention is mostly confined to the study of μ = EX where the random variable X has the stationary distribution for {Xn }. Even for special cases such as i.i.d. Yn or α = 0, little explicit information appears to be available on the distribution of X or μ . Accordingly, bounding techniques that have been exploited in queueing theory are used to study μ . The various bounds are illustrated numerically in a range of special cases.

Exergy-Based Optimization of Sub- and Supercritical Thermal Energy Storage Systems

2014 ◽  
Author(s):  
Louis A. Tse ◽  
Reza Baghaei Lakeh ◽  
Richard E. Wirz ◽  
Adrienne S. Lavine
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Energy And Exergy

In this work, energy and exergy analyses are applied to a thermal energy storage system employing a storage medium in the two-phase or supercritical regime. First, a numerical model is developed to investigate the transient thermodynamic and heat transfer characteristics of the storage system by coupling conservation of energy with an equation of state to model the spatial and temporal variations in fluid properties during the entire working cycle of the TES tank. Second, parametric studies are conducted to determine the impact of key variables (such as heat transfer fluid mass flow rate and maximum storage temperature) on both energy and exergy efficiencies. The optimum heat transfer fluid mass flow rate during charging must balance exergy destroyed due to heat transfer and exergy destroyed due to pressure losses, which have competing effects. Similarly, the optimum maximum storage fluid temperature is evaluated to optimize exergetic efficiency. By incorporating exergy-based optimization alongside traditional energy analyses, the results of this study evaluate the optimal values for key parameters in the design and operation of TES systems, as well as highlight opportunities to minimize thermodynamic losses.

scholarly journals Carbonation Reaction of Lithium Hydroxide during Low Temperature Thermal Energy Storage Process

2021 ◽  
Vol 9 (9) ◽  
pp. 1621-2630
Author(s):  
Jun Li ◽  
Tao Zeng ◽  
Noriyuki Kobayashi ◽  
Rongjun Wu ◽  
Haotai Xu ◽  
...  
Keyword(s):  
Energy Storage ◽  
Low Temperature ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Lithium Hydroxide ◽  
Storage Process ◽  
Carbonation Reaction

New bounds for the thermal energy storage process with stationary input

1982 ◽  
Vol 19 (4) ◽  
pp. 894-899 ◽  
Author(s):  
J. Haslett
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Systems ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Storage Process

The process {Xn}, defined by Xn+ 1 = max{Yn+ 1 + αßXn, ßXn}, with αand ß in [0, 1) and {Yn} stationary, arises in studies of solar thermal energy systems. Bounds for the stationary mean EX are given, which are more general and in some cases tighter, than those previously available.

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