A PCM/Forced Convection Conjugate Transient Analysis of Energy Storage Systems With Annular and Countercurrent Flows

1991 ◽  
Vol 113 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Y. Cao ◽  
A. Faghri ◽  
A. Juhasz

Latent heat energy storage systems with both annular and countercurrent flows are modeled numerically. The change of phase of the phase-change material (PCM) and the transient forced convective heat transfer for the transfer fluid are solved simultaneously as a conjugate problem. A parametric study and a system optimization are conducted. It is found that the energy storage system with the counter-current flow is an efficient way to absorb heat energy in a short period for pulsed power load space applications.

2017 ◽  
Vol 68 (11) ◽  
pp. 2641-2645
Author(s):  
Alexandru Ciocan ◽  
Ovidiu Mihai Balan ◽  
Mihaela Ramona Buga ◽  
Tudor Prisecaru ◽  
Mohand Tazerout

The current paper presents an energy storage system that stores the excessive energy, provided by a hybrid system of renewable energy sources, in the form of compressed air and thermal heat. Using energy storage systems together with renewable energy sources represents a major challenge that could ensure the transition to a viable economic future and a decarbonized economy. Thermodynamic calculations are conducted to investigate the performance of such systems by using Matlab simulation tools. The results indicate the values of primary and global efficiencies for various operating scenarios for the energy storage systems which use compressed air as medium storage, and shows that these could be very effective systems, proving the possibility to supply to the final user three types of energy: electricity, heat and cold function of his needs.


2020 ◽  
Vol 173 ◽  
pp. 03004
Author(s):  
Darío Benavides ◽  
Paúl Arévalo ◽  
Luis G. Gonzalez ◽  
José A. Aguado

The importance of energy storage systems is increasing in microgrids energy management. In this study, an analysis is carried out for different types of energy storage technologies commonly used in the energy storage systems of a microgrid, such as: lead acid batteries, lithium ion batteries, redox vanadium flux batteries and supercapacitors. In this work, it is analyzed the process of charging and discharging (slow and fast) in these systems, the calculation of energy efficiency, performance and energy supplied under different load levels, in its normal operating conditions and installed power capacity is developed. The results allow us to choose the optimal conditions of charge and discharge at different levels of reference power, analyzing the strengths and weaknesses of the characteristics of each storage system within a microgrid.


2019 ◽  
Vol 11 (1) ◽  
pp. 186 ◽  
Author(s):  
Byuk-Keun Jo ◽  
Seungmin Jung ◽  
Gilsoo Jang

Energy storage systems are crucial in dealing with challenges from the high-level penetration of renewable energy, which has inherently intermittent characteristics. For this reason, various incentive schemes improving the economic profitability of energy storage systems are underway in many countries with an aim to expand the participation rate. The electricity charge discount program, which was introduced in 2015 in Korea, is one of the policies meant to support the economic feasibility of demand-side energy storage systems. This paper quantitatively evaluated the impact of the electricity charge discount program on the economic feasibility of behind-the-meter energy storage systems. In this work, we first summarized how electricity customers can benefit from behind-the-meter energy storage systems. In addition, we represented details of the structure that make up the electricity charge discount program, i.e., how the electricity charge is discounted through the discount scheme. An optimization problem that establishes a charge and discharge schedule of an energy storage system to minimize each consumer’s electricity expenditure was defined and formulated as well. The case study results indicated that the electricity charge discount program has improved the profitability of behind-the-meter energy storage systems, and this improved profitability led to investment in behind-the-meter energy storage systems in Korea. As a result of the electricity charge discount program, Korea’s domestic demand side energy storage system market size, which was only 27 billion dollars in 2015 in Korea, has grown to 825 billion dollars in 2018.


Author(s):  
Xiao Ping Wu ◽  
Masataka Mochizuki ◽  
Koichi Mashiko ◽  
Thang Nguyen ◽  
Tien Nguyen ◽  
...  

In this paper, design and economic analysis for applying a novel type of heat pipe into cold energy storage systems have been proposed and discussed. The heat pipe cold energy storage systems can be designed into several types that are ice storage, cold water storage and pre-cool heat exchanger. Those systems can be used for co-operating with conventional chiller system for cooling data centers. The heat load used for discussing in this paper is 8800 kW which represents a large scale data center. The methodology addressed in this paper can be also converted into the middle and small sizes of the data centers. This type of storage system will help to downsize the chiller and decrease its running time that would be able to save significant electricity cost and decrease green house gas emissions from the electricity generation. The proposed systems can be easily connected into the existing conventional systems without major design changes. The analysis in this paper is using Air Freezing Index AFI >= 400 °C-days/year for sizing the heat pipe modules. For the locations where AFI has different value the storage size will be varied accordingly. The paper also addressed a result that an optimum size of cold energy storage system that should be designed at a level to handle 60% of total yearly heat load of a data center.


Author(s):  
Sammy Houssainy ◽  
Reza Baghaei Lakeh ◽  
H. Pirouz Kavehpour

Human activity is overloading our atmosphere with carbon dioxide and other global warming emissions. These emissions trap heat, increase the planet’s temperature, and create significant health, environmental, and climate issues. Electricity production accounts for more than one-third of U.S. global warming emissions, with the majority generated by coal-fired power plants. These plants produce approximately 25 percent of total U.S. global warming emissions. In contrast, most renewable energy sources produce little to no global warming emissions. Unfortunately, generated electricity from renewable sources rarely provides immediate response to electrical demands, as the sources of generation do not deliver a regular supply easily adjustable to consumption needs. This has led to the emergence of storage as a crucial element in the management of energy, allowing energy to be released into the grid during peak hours and meet electrical demands. Compressed air energy storage can potentially allow renewable energy sources to meet electricity demands as reliably as coal-fired power plants. Most compressed air energy storage systems run at very high pressures, which possess inherent problems such as equipment failure, high cost, and inefficiency. This research aims to illustrate the potential of compressed air energy storage systems by illustrating two different discharge configurations and outlining key variables, which have a major impact on the performance of the storage system. Storage efficiency is a key factor to making renewable sources an independent form of sustainable energy. In this paper, a comprehensive thermodynamic analysis of a compressed air energy storage system is presented. Specifically, a detailed study of the first law of thermodynamics of the entire system is presented followed by a thorough analysis of the second law of thermodynamics of the complete system. Details of both discharge and charge cycles of the storage system are presented. The first and second law based efficiencies of the system are also presented along with parametric studies, which demonstrates the effects of various thermodynamic cycle variables on the total round-trip efficiency of compressed air energy storage systems.


Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2006 ◽  
Author(s):  
Matteo Moncecchi ◽  
Claudio Brivio ◽  
Stefano Mandelli ◽  
Marco Merlo

Off-grid power systems based on photovoltaic and battery energy storage systems are becoming a solution of great interest for rural electrification. The storage system is one of the most crucial components since inappropriate design can affect reliability and final costs. Therefore, it is necessary to adopt reliable models able to realistically reproduce the working condition of the application. In this paper, different models of lithium-ion battery are considered in the design process of a microgrid. Two modeling approaches (analytical and electrical) are developed based on experimental measurements. The derived models have been integrated in a methodology for the robust design of off-grid electric power systems which has been implemented in a MATLAB-based computational tool named Poli.NRG (POLItecnico di Milano—Network Robust desiGn). The procedure has been applied to a real-life case study to compare the different battery energy storage system models and to show how they impact on the microgrid design.


Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3498 ◽  
Author(s):  
Tiezhou Wu ◽  
Wenshan Yu ◽  
Lujun Wang ◽  
Linxin Guo ◽  
Zhiquan Tang

Traditional hierarchical control of the microgrid does not consider the energy storage status of a distributed hybrid energy storage system. This leads to the inconsistency of the remaining capacity of the energy storage system in the process of system operation, which is not conducive to the safe and stable operation of the system. In this paper, an improved hierarchical control strategy is proposed: the first allocation layer completes the allocation between the distribution energy storage systems considering the state of hybrid energy storage systems, and the second allocation layer realizes the allocation within the hybrid energy storage systems based on variable time constant low-pass filtering. Considering the extreme conditions of energy storage systems, the transfer current is introduced in the second allocation process. The SOC (stage of charge) of the supercapacitor is between 40% and 60%, which ensures that the supercapacitor has enough margin to respond to the power demand. An example of a 300 MW photovoltaic microgrid system in a certain area is analyzed. Compared with the traditional hierarchical control, the proposed control strategy can reduce the SOC change of a hybrid energy storage system by 9% under the same conditions, and make the supercapacitor active after power stabilization, which is helpful to the stable operation of the microgrid.


Author(s):  
Chang Liu ◽  
Robynne E. Murray ◽  
Dominic Groulx

Phase change materials (PCMs) inside latent heat energy storage systems (LHESS) can be used to store large amounts of thermal energy in relatively small volumes. However, such systems are complicated to design from a heat transfer point of view since the low thermal conductivity of PCMs makes charging and discharging those systems challenging on a usable time scale. Results of experiments performed on both a vertical and a horizontal cylindrical LHESS, during charging, discharging and simultaneous charging/discharging, are presented in this paper. Both LHESS are made of acrylic plastic, the horizontal LHESS has one 1/2″ copper pipe passing through its center. The vertical LHESS has two 1/2″ copper pipes, one through which hot water flows, and the other through which cold water flows. Each of the pipes has four longitudinal fins to enhance the overall rate of heat transfer to and from the PCM, therefore reducing the time required for charging and discharging. The objective of this work is to determine the phase change behavior of the PCM during the operation of the LHESS, as well as the heat transfer processes within the LHESS. Natural convection was found to play a crucial role during charging (melting) and during simultaneous charging/discharging (in the vertical LHESS). However, during discharging, the effect of natural convection was reduced in both systems.


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