Performance of Large-Scale Seasonal Thermal Energy Stores

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
F. Ochs ◽  
W. Heidemann ◽  
H. Müller-Steinhagen
Keyword(s):  
Thermal Energy ◽  
Large Scale ◽  
Fossil Fuels ◽  
Waste Heat ◽  
Type System ◽  
Solar Thermal Energy ◽  
Construction Costs ◽  
The Past ◽  
Energy Stores ◽  
Construction Type

More than 30 international research and pilot seasonal thermal energy stores (TESs) were realized within the past 30 years. Experiences with operation of these systems show that TES are technically feasible and work well. Seasonal storage of solar thermal energy or of waste heat from heat and power cogeneration plants can significantly contribute to substitute fossil fuels in future energy systems. However, performance with respect to thermal losses and lifetime has to be enhanced, while construction costs have to be further reduced. This paper gives an overview about the state-of-the-art of seasonal thermal energy storage with the focus on tank and pit TES construction. Aspects of TES modeling are given. Based on modeled and measured data, the influence of construction type, system configuration, and boundary conditions on thermal losses of large-scale TES is identified. The focus is on large-scale applications with tank and pit thermal energy stores and on recent investigations on suitable materials and constructions. Furthermore, experiences with the operation of these systems with respect to storage performance are discussed.

Design and Optimization of Integrated Distributed Energy Systems for Off-grid Buildings

2021 ◽  
pp. 1-27
Author(s):  
Jian Zhang ◽  
Heejin Cho ◽  
Pedro Mago
Keyword(s):  
Energy Storage ◽  
Optimal Design ◽  
Power Systems ◽  
Thermal Energy ◽  
Waste Heat ◽  
Carbon Dioxide Emission ◽  
Energy Systems ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Distributed Energy

Abstract Off-grid concepts for homes and buildings have been a fast-growing trend worldwide in the last few years because of the rapidly dropping cost of renewable energy systems and their self-sufficient nature. Off-grid homes/buildings can be enabled with various energy generation and storage technologies, however, design optimization and integration issues have not been explored sufficiently. This paper applies a multi-objective genetic algorithm (MOGA) optimization to obtain an optimal design of integrated distributed energy systems for off-grid homes in various climate regions. Distributed energy systems consisting of renewable and non-renewable power generation technologies with energy storage are employed to enable off-grid homes/buildings and meet required building electricity demands. In this study, the building types under investigation are residential homes. Multiple distributed energy resources are considered such as combined heat and power systems (CHP), solar photovoltaic (PV), solar thermal collector (STC), wind turbine (WT), as well as battery energy storage (BES) and thermal energy storage (TES). Among those technologies, CHP, PV, and WT are used to generate electricity, which satisfies the building's electric load, including electricity consumed for space heating and cooling. Solar thermal energy and waste heat recovered from CHP are used to partly supply the building's thermal load. Excess electricity and thermal energy can be stored in the BES and TES for later use. The MOGA is applied to determine the best combination of DERs and each component's size to reduce the system cost and carbon dioxide emission for different locations. Results show that the proposed optimization method can be effectively and widely applied to design integrated distributed energy systems for off-grid homes resulting in an optimal design and operation based on a trade-off between economic and environmental performance.

scholarly journals Energy Analysis of a Novel Ejector-Compressor Cooling Cycle Driven by Electricity and Heat (Waste Heat or Solar Energy)

2020 ◽  
Vol 12 (19) ◽  
pp. 8178
Author(s):  
Fahid Riaz ◽  
Kah Hoe Tan ◽  
Muhammad Farooq ◽  
Muhammad Imran ◽  
Poh Seng Lee
Keyword(s):  
Low Temperature ◽  
Thermal Energy ◽  
Waste Heat ◽  
Solar Thermal ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Low Grade ◽  
Solar Thermal Energy ◽  
Temperature Heat ◽  
Vapour Compression

Low-grade heat is abundantly available as solar thermal energy and as industrial waste heat. Non concentrating solar collectors can provide heat with temperatures 75–100 °C. In this paper, a new system is proposed and analyzed which enhances the electrical coefficient of performance (COP) of vapour compression cycle (VCC) by incorporating low-temperature heat-driven ejectors. This novel system, ejector enhanced vapour compression refrigeration cycle (EEVCRC), significantly increases the electrical COP of the system while utilizing abundantly available low-temperature solar or waste heat (below 100 °C). This system uses two ejectors in an innovative way such that the higher-pressure ejector is used at the downstream of the electrically driven compressor to help reduce the delivery pressure for the electrical compressor. The lower pressure ejector is used to reduce the quality of wet vapour at the entrance of the evaporator. This system has been modelled in Engineering Equation Solver (EES) and its performance is theoretically compared with conventional VCC, enhanced ejector refrigeration system (EERS), and ejection-compression system (ECS). The proposed EEVCRC gives better electrical COP as compared to all the three systems. The parametric study has been conducted and it is found that the COP of the proposed system increases exponentially at lower condensation temperature and higher evaporator temperature. At 50 °C condenser temperature, the electrical COP of EEVCRC is 50% higher than conventional VCC while at 35 °C, the electrical COP of EEVCRC is 90% higher than conventional VCC. For the higher temperature heat source, and hence the higher generator temperatures, the electrical COP of EEVCRC increases linearly while there is no increase in the electrical COP for ECS. The better global COP indicates that a small solar collector will be needed if this system is driven by solar thermal energy. It is found that by using the second ejector at the upstream of the electrical compressor, the electrical COP is increased by 49.2% as compared to a single ejector system.

scholarly journals Novel Bio-Based Pomelo Peel Flour/Polyethylene Glycol Composite Phase Change Material for Thermal Energy Storage

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2043 ◽  
Author(s):  
Hai-Chen Zhang ◽  
Ben-hao Kang ◽  
Xinxin Sheng ◽  
Xiang Lu
Keyword(s):  
Thermal Stability ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Waste Heat ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Pomelo Peel

A series of novel bio-based form stable composite phase-change materials (fs-CPCMs) for solar thermal energy storage and management applications were prepared, using the pomelo peel flour (PPF) as the supporting matrix and poly (ethylene glycol) (PEG) or isocyanate-terminated PEG to induce a phase change. The microscopic structure, crystalline structures and morphologies, phase change properties, thermal stability, light-to-thermal conversion behavior, and thermal management characteristics of the obtained fs-CPCMs were studied. The results indicate that the obtained fs-CPCM-2 presented remarkable phase-change performance and high thermal stability. The melting latent heat and crystallization heat for fs-CPCM-2 are 143.2 J/g and 141.8 J/g, respectively, and its relative enthalpy efficiency ( λ ) is 87.4%, which are higher than most reported values in the related literature. The obtained novel bio-based fs-CPCM-2 demonstrated good potential for applications in solar thermal energy storage and waste heat recovery.

scholarly journals A New Wind Power Accommodation Strategy for Combined Heat and Power System Based on Bi-Directional Conversion

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2458 ◽  
Author(s):  
Yanhong Luo ◽  
Zhenxing Yin ◽  
Dongsheng Yang ◽  
Bowen Zhou
Keyword(s):  
Wind Power ◽  
Thermal Energy ◽  
Northeast China ◽  
Large Scale ◽  
Fossil Fuels ◽  
Electrical Power ◽  
Combined Heat And Power ◽  
Storage Device ◽  
Reduce Emissions ◽  
Power To Gas

The extensive use of wind power can not only reduce dependence on fossil fuels, but also reduce emissions of polluted gases. However, large-scale wind power curtailments often occur in northeast China during the heat supply season, due to the fact that most of electrical demand is covered by the electrical power of the combined heat and power (CHP) during the off-peak hours. At present, for northeast China with heating demand, most of the research only focuses on how to accommodate more wind power on the spot by using one-directional conversion of the electric and thermal energy. But it is still difficult to realize the bi-directional conversion between the electro-gas or electro-thermal energy. In this paper, a combined electro-gas bi-directional conversion system (CEGBCS) is established by adding the power to gas (P2G), fuel cell and heat storage device in CHP system. This CEGBCS can not only realize bi-directional conversion of the electricity and gas, but also decouple the two operation modes of CHP unit, which greatly improve the ability of system to accommodate additional wind power. Finally, the effectiveness of the proposed CEGBCS is verified by comparing with two traditional methods.

Numerical Studies on the Performance of a Bubble Pump

2013 ◽  
Vol 330 ◽  
pp. 203-208 ◽  
Author(s):  
L. Bruno Augustin ◽  
Jigar Golecha ◽  
K.G. Sai Shreenaath ◽  
Vishnu Swami ◽  
M. Suresh
Keyword(s):  
Thermal Energy ◽  
Waste Heat ◽  
Electrical Energy ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Solar Thermal Energy ◽  
Thermally Driven ◽  
Absorption Refrigeration System ◽  
Bubble Pump

Increase in the consumption of electrical energy worldwide has laid the emphasis on replacing electrical energy with thermal energy wherever possible. In this paper, the bubble pump, which is ‘heart’ of diffusion- absorption refrigeration system, has been investigated numerically. A thermally driven bubble pump, which can be powered by waste heat or solar thermal energy, is used to lift the liquid. As a result of the absence of any mechanical moving part, the refrigerator is silent and very reliable in addition to aneconomicalandenvironmental friendlydevice. The concept of such a pump is already in existence but optimization studies are yet to be extensively investigated. This paper deals with the optimization of various parameters of the bubble pump usingwateras the working fluid. Parametric studies are carried out and a design optimization for maximum efficiency is performed for various operating conditions.Numerical simulation of the bubble pump is carried out using simple numerical equations which assume slug flow in the bubble pump. The diameter of the pipe and the position of the heating element are varied and the effect it has on time taken, pumping ratio and pumping ratio for one pumping cycle is studied.

Sign in / Sign up

Export Citation Format

Share Document