Letteratura scientifica selezionata sul tema "LHTES SYSTEM"
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Articoli di riviste sul tema "LHTES SYSTEM"
1
Yanbing, Kang, Zhang Yinping, Jiang Yi e Zhu Yingxin. "A General Model for Analyzing the Thermal Characteristics of a Class of Latent Heat Thermal Energy Storage Systems". Journal of Solar Energy Engineering 121, n. 4 (1 novembre 1999): 185–93. http://dx.doi.org/10.1115/1.2888165.
Testo completoAbstract (sommario):
The present study describes and classifies latent heat thermal energy storage (LHTES) systems according to their structural characteristics. A general model is developed for analyzing the thermal characteristics of the various typical LHTES systems to simulate thermal characteristics such as instantaneous heat transfer rate, instantaneous thermal storage capacity, etc. of the various typical LHTES systems. The model can calculate some important but difficult to measure system parameters for monitoring the charging or discharging processes of the systems. The model is verified using experimental data in the literature. Results from the model can be used to discuss the influence of the characteristic geometric parameters of LHTES units, the physical properties of the phase change material (PCM), the flow type and the velocity of heat transfer fluid (HTF) on the system thermal performance and to identify the key factors influencing the system thermal performance. The general model can be used to select and optimize the system structure and to simulate the thermal behavior of various typical LHTES systems.
2
Oni, Taiwo O., Jacob B. Awopetu, Samson A. Adeleye, Daniel C. Uguru-Okorie, Anthony A. Adeyanju e Niyi E. Olukayode. "Development of a Latent Heat Thermal Energy Storage Material-Based Refrigeration System". International Journal of Heat and Technology 39, n. 2 (30 aprile 2021): 469–76. http://dx.doi.org/10.18280/ijht.390216.
Testo completoAbstract (sommario):
The present research focuses on application of thermal energy storage on a convectional refrigerator to enhance its performance. Salt hydrate was used as latent heat thermal energy storage (LHTES) material to convert the convectional refrigerator to a LHTES material-based refrigerator. The cabinet of the convectional refrigerator was loaded with 10 kg of water at a temperature of 28℃ and experiments were conducted on it to know the time taken for the evaporator temperature (TE) to reach -5℃, and determine the performance characteristics of the convectional refrigerator. The experiments were repeated on the LHTES material-based refrigerator to compare its performance characteristics with those of the convectional refrigerator. The results reveal that the evaporator of the LHTES material-based refrigerator attains the temperature of -5℃ forty minutes before the same temperature (-5℃) was attained in the evaporator of the convectional refrigerator. For the interval of evaporator temperature (−5∘C≤TE≤−1∘C) considered for evaluation of the performance characteristics of the refrigerators in this work, when TE drops from 1℃ to -5℃, the coefficient of performance (COP) for the LHTES material-based refrigerator and convectional refrigerator decreases from 7.36 to 4.62 and 6.44 to 4.15, respectively; the refrigerating effect decreases from 118.41 kJ/kg to 111.80 kJ/kg and 113.37 kJ/kg to 106.69 kJ/kg, respectively; the compressor work increases from 15.10 kJ/kg to 23.18 kJ/kg and 17.60 kJ/kg to 25.68 kJ/kg, respectively. The higher value of the COP and refrigerating effect, and the lower value of the compressor work of the LHTES material-based refrigerator compared with those of the convectional refrigerator imply that there is an improvement in the performance of the refrigerator with the LHTES material. The current work broadens research on the use of a LHTES materials to enhance the performance of a refrigerator.
3
Modi, Nishant, Xiaolin Wang e Michael Negnevitsky. "Solar Hot Water Systems Using Latent Heat Thermal Energy Storage: Perspectives and Challenges". Energies 16, n. 4 (16 febbraio 2023): 1969. http://dx.doi.org/10.3390/en16041969.
Testo completoAbstract (sommario):
Domestic water heating accounts for 15% to 27% of the total energy consumption in buildings in Australia. Over the past two decades, the latent heat thermal energy storage (LHTES) system has been widely investigated as a way to reduce fossil fuel consumption and increase the share of renewable energy in solar water heating. However, the research has concentrated on the geometric optimisation of the LHTES heat exchanger for the past few years, and this might not be sufficient for commercialisation. Moreover, recent review papers mainly discussed the development of a particular heat-transfer improvement technique. This paper presents perspectives on various solar hot water systems using LHTES to shift focus to on-demand performance studies, as well as structure optimisation studies for faster commercialisation. Future challenges are also discussed. Since the topic is an active area of research, this paper focuses on references that showcase the overall performance of LHTES-assisted solar hot water systems and cannot include all published work in the discussion. This perspective paper provides directional insights to researchers for developing an energy-efficient solar hot water system using LHTES.
4
Chocontá Bernal, Daniel, Edmundo Muñoz, Giovanni Manente, Adriano Sciacovelli, Hossein Ameli e Alejandro Gallego-Schmid. "Environmental Assessment of Latent Heat Thermal Energy Storage Technology System with Phase Change Material for Domestic Heating Applications". Sustainability 13, n. 20 (13 ottobre 2021): 11265. http://dx.doi.org/10.3390/su132011265.
Testo completoAbstract (sommario):
The emissions generated by the space and water heating of UK homes need to be reduced to meet the goal of becoming carbon neutral by 2050. The combination of solar (S) collectors with latent heat thermal energy storage (LHTES) technologies with phase change materials (PCM) can potentially help to achieve this goal. However, there is limited understanding of the environmental sustainability of LHTES technologies from a full life cycle perspective. This study assesses for the first time 18 environmental impacts of a full S-LHTES-PCM system from a cradle to grave perspective and compares the results with the most common sources of heat in UK homes. The results show that the system’s main environmental hotspots are the solar collector, the PCM, the PCM tank, and the heat exchanger. The main cause of most of the impacts is the extensive consumption of electricity and heat during the production of raw materials for these components. The comparison with other sources of household heat (biomass, heat pump, and natural gas) indicates that the S-LHTES-PCM system generates the highest environmental impact in 11 of 18 categories. However, a sensitivity analysis based on the lifetime of the S-LHTES-PCM systems shows that, when the lifetime increases to 40 years, almost all the impacts are significantly reduced. In fact, a 40-year S-LHTES-PCM system has a lower global warming potential than natural gas.
5
Chocontá Bernal, Daniel, Edmundo Muñoz, Giovanni Manente, Adriano Sciacovelli, Hossein Ameli e Alejandro Gallego-Schmid. "Environmental Assessment of Latent Heat Thermal Energy Storage Technology System with Phase Change Material for Domestic Heating Applications". Sustainability 13, n. 20 (13 ottobre 2021): 11265. http://dx.doi.org/10.3390/su132011265.
Testo completoAbstract (sommario):
The emissions generated by the space and water heating of UK homes need to be reduced to meet the goal of becoming carbon neutral by 2050. The combination of solar (S) collectors with latent heat thermal energy storage (LHTES) technologies with phase change materials (PCM) can potentially help to achieve this goal. However, there is limited understanding of the environmental sustainability of LHTES technologies from a full life cycle perspective. This study assesses for the first time 18 environmental impacts of a full S-LHTES-PCM system from a cradle to grave perspective and compares the results with the most common sources of heat in UK homes. The results show that the system’s main environmental hotspots are the solar collector, the PCM, the PCM tank, and the heat exchanger. The main cause of most of the impacts is the extensive consumption of electricity and heat during the production of raw materials for these components. The comparison with other sources of household heat (biomass, heat pump, and natural gas) indicates that the S-LHTES-PCM system generates the highest environmental impact in 11 of 18 categories. However, a sensitivity analysis based on the lifetime of the S-LHTES-PCM systems shows that, when the lifetime increases to 40 years, almost all the impacts are significantly reduced. In fact, a 40-year S-LHTES-PCM system has a lower global warming potential than natural gas.
6
Zhang, Yinping, Yan Su, Yingxin Zhu e Xianxu Hu. "A General Model for Analyzing the Thermal Performance of the Heat Charging and Discharging Processes of Latent Heat Thermal Energy Storage Systems*". Journal of Solar Energy Engineering 123, n. 3 (1 gennaio 2001): 232–36. http://dx.doi.org/10.1115/1.1374206.
Testo completoAbstract (sommario):
During melting of phase change materials (PCM) encapsulated in a container, the solid PCM sinks to the bottom or floats to the top of the container according to the gravitational force and buoyancy resulting from the difference between solid and liquid densities. Compared with the solidification process, the melting process has a quite different behavior. Although the heat transfer characteristics of melting processes in various typical kinds of containers have been studied, the general model for analyzing the thermal performance of both melting and solidification processes of latent heat thermal energy storage (LHTES) systems composed of PCM capsules has not been presented in the literature. The present paper describes such a model which can be used to analyze the instantaneous temperature distribution, instantaneous heat transfer rate, and thermal storage capacity of a LHTES system. For solidification, the model is validated with the results in the literature. The thermal performance during melting of a LHTES system composed of PCM spheres is analyzed as an example. The model is not limited to a specific system or a specific PCM, so it can be used to select and optimize system design and to simulate the thermal behavior of various typical LHTES systems.
7
Paroutoglou, Evdoxia, Peter Fojan, Leonid Gurevich, Simon Furbo, Jianhua Fan, Marc Medrano e Alireza Afshari. "A Numerical Parametric Study of a Double-Pipe LHTES Unit with PCM Encapsulated in the Annular Space". Sustainability 14, n. 20 (17 ottobre 2022): 13317. http://dx.doi.org/10.3390/su142013317.
Testo completoAbstract (sommario):
Latent heat thermal energy storage (LHTES) with Phase Change Materials (PCM) represents an interesting option for Thermal Energy Storage (TES) applications in a wide temperature range. A tubular encapsulation model of an LHTES with PCM was developed, and the calculated data were analyzed. In addition, a parametric analysis for the preferable system geometry is presented. Organic paraffin RT18 with a melting point of 18 °C was utilized as PCM for different geometries of LHTES, and the addition of internal and external fins and their influence on LHTES thermal conductivity was investigated. One-step heat exchange from outdoor air to PCM and from PCM to water characterizes the LHTES system in solidification and melting processes, respectively. A 2D axisymmetric model was developed using Comsol Multiphysics 6.0. The LHTES unit performance with PCM organic paraffin RT18 encapsulated in electrospun fiber matrices was analyzed. The study results show that longer internal fins shorten the melting and solidification time. Direct contact of PCM electrospun fiber matrix with 23 °C water showed instant melting, and the phase change process was accelerated by 99.97% in the discharging cycle.
8
Shank, Kyle, Jessica Bernat, Ethan Regal, Joel Leise, Xiaoxu Ji e Saeed Tiari. "Experimental Study of Varying Heat Transfer Fluid Parameters within a Latent Heat Thermal Energy Storage System Enhanced by Fins". Sustainability 14, n. 14 (21 luglio 2022): 8920. http://dx.doi.org/10.3390/su14148920.
Testo completoAbstract (sommario):
Latent heat thermal energy storage (LHTES) systems can be used to combat the limited collection and long-term storage of renewable energy sources. The key component of an LHTES system is its phase change material (PCM), which thermally stores energy. Despite extensive research on thermal conductivity enhancement within PCM, little attention has been paid to the heat transfer fluid (HTF) within the system. This study aimed to observe the impact of variable HTF flow rates and temperatures on the speed of charging and discharging an LHTES system enhanced with annular fins. Two copper fin configurations of 10 and 20 annular fins were tested within an LHTES system with Rubitherm RT-55 PCM. The configurations were tested during charging processes with HTF parameters of 65 °C and 70 °C at 1, 2, and 3 gpm. Discharging processes were tested with HTF parameters of 15 °C and 20 °C at 0.5, 1, and 1.5 gpm. The system energy response and PCM temperature were recorded throughout the tests. The results of the study revealed that a higher flow rate produced a shorter processing time, but furthermore, that a larger temperature gradient between the PCM and HTF caused a more significant decrease in charging and discharging times.
9
Paroutoglou, Evdoxia, Alireza Afshari, Niels Chr Bergsøe, Peter Fojan e Göran Hultmark. "A PCM based cooling system for office buildings: a state of the art review". E3S Web of Conferences 111 (2019): 01026. http://dx.doi.org/10.1051/e3sconf/201911101026.
Testo completoAbstract (sommario):
Cooling of air in buildings has a significant effect on thermal comfort and, consequently, productivity of office occupants. This study presents a state of the art review of energy efficient cooling systems that will provide occupants in buildings with satisfying thermal comfort. Using high-temperature cooling systems combined with renewable energy sources increases the energy efficiency in buildings. Latent heat thermal energy storage (LHTES) using Phase Change Materials (PCM) is a renewable energy source implemented in space cooling applications due to its high energy storage density. Since the share of commercial buildings in need of cooling is increasing, there is a need for developing new technical solutions in order to reduce the energy use without compromising thermal comfort. To this end, a proposed ventilation system, preliminarily analyzed in this paper, is expected to reduce further the energy use. The ventilation system is composed of an air handling unit, a 2-pipe active chilled beam system, and a cooling system including a LHTES using PCM. Few researchers have investigated chilled water air-conditioning systems that integrate a LHTES using PCM. In this review, function characteristics, possibilities and limitations of existing systems are discussed.
10
Migla, Lana, Raimonds Bogdanovics e Kristina Lebedeva. "Performance Improvement of a Solar-Assisted Absorption Cooling System Integrated with Latent Heat Thermal Energy Storage". Energies 16, n. 14 (11 luglio 2023): 5307. http://dx.doi.org/10.3390/en16145307.
Testo completoAbstract (sommario):
Phase change materials (PCMs) have emerged as promising solutions for latent heat thermal energy storage (LHTES) systems, offering considerable potential for storing energy derived from renewable sources across various engineering applications. The present study focused on optimization of solar cooling system by integrating LHTES with different PCM tank configurations. TRNSYS simulation software was selected for the study, and the collected experimental data from laboratory system prototype were used for system validation. The results indicate that the use of PCM led to a noteworthy decrease of 6.2% in auxiliary energy consumption. Furthermore, the time during which the heat carrier temperature flow exceeded 90 °C from the storage tank to the auxiliary fluid heater was extended by 27.8% when PCM was utilized compared to that of its absence. The use of PCM in LHTES is more effective under variable weather conditions. On the day when changes in weather conditions were observed, around 98% of the cooling load was provided by produced sun energy. The results of the research can be used to optimize the solar cooling system, which will help reduce the environmental impact of cooling systems running on non-renewable fuels.
Tesi sul tema "LHTES SYSTEM"
1
Egersand, Anton, e Emil Fransson. "THE POTENTIAL OF A LATENT HEAT THERMAL ENERGY STORAGE : An Investigation on Rocklunda's Sport Facilities". Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55539.
Testo completoAbstract (sommario):
The world is ever increasing in its energy usage, making energy that is sustainable and secure harder to achieve. To fulfil the Paris agreement to limit global warming, the world needs to transition from fossil fuels toward more renewable energy sources, like wind and solar, but these sources have fluctuation in supply which often create a mismatch with demand. To combat this issue, thermal energy storage can be utilized, and one such technology is latent heat thermal energy storage. This study aimed to investigate the potential of latent heat thermal energy storage by developing a simple model of such a system and studying its impact on Rocklunda’s sport facilities. The model was developed by using MATLAB, primarily using the photovoltaic overproduction of the facilities to store as energy for the latent heat thermal energy storage. The implemented storage, based on the model’s result, had overall positive impact on the facilities. The optimized storage capacity was about 510 kWh, which throughout the storage’s lifetime would save ~4 989 MWh worth of heat by using the best performing phase change material: aluminium-silicon. The storage would also be able to utilize ~82% of the annual photovoltaic overproduction that would otherwise be unused/sold as well as reducing the heat demand by ~12% by using the heat stored via the storage. The implementation also proved to have beneficial effects on the environment as the saved heat was the equivalent of mitigating ~304 ton of CO2 emissions. Furthermore, there is a profit of ~236 000 SEK.Reduction and Reuse of energy with interconnected Distribution and Demand (R2D2)
2
RANA, SACHIN. "CFD SIMULATION OF SHELL AND TUBE HEAT EXCHANGER FILLED WITH PHASE CHANGE MATERIAL FOR SOLAR WATER HEATING SYSTEM". Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/20147.
Testo completoAbstract (sommario):
Solar energy, the most promising source of energy, requires thermal energy storage (TES) due to
its intermittent nature. Storage of thermal energy can take the form of sensible heat storage
(SHS), latent heat storage (LHS), and thermo-chemical storage (TCS). The amount of energy
that is stored in SHS depends on the specific heat of the substance, the change in temperature,
and the mass of the storage material since heat energy is retained by raising the temperature of
the storage material without going through a phase transition. However, LHS involves a phase
transition, when heated to the constant temperature, between solid-liquid, solid-solid, and liquid gas states and vice versa. Solid-solid phase transitions require a lower energy storage capacity
than liquid-gas phase transitions which require a large increase in volume. As a result, the solid liquid transformation is most commonly used in LHS applications because it is more efficient
than other transformations.
In this study, the methods of enhancing the heat transmission in a latent heat thermal energy
storage (LHTES) system with a heat exchanger of shell & tube type having a phase change
material (PCM) in shell region, known as PCM heat exchanger (PCMHE), and carrying a
number of tubes of circular, elliptical and square shape, to flow of a heat transfer fluid (HTF)
using a two-dimension (2D) computational fluid dynamics (CFD) model has been presented.
Enhancement of heat transfer in the LHTES system may be obtained either by using a suitable
geometric configuration of PCMHE and/or by increasing the thermal conductivity of PCM. Heat
transfer enhancements in LHTES systems can be achieved by using extended surfaces like fins
and heat pipes. To enhance the heat transmission between tubes and PCM, a number of
rectangular fins are attached to the outer surface of the circular, elliptical, and square tubes of the
PCMHE.
Geometrical modeling of PCMHE of shell and tube type, in which a solid Gallium as a PCM is
filled in the outer shell and an HTF is flowing inside tubes, has been done in Solid Works. In this
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work, the outer shell of PCMHE is selected in two different shapes: square and circular. The
tubes inside the outer shell of PCMHE are also selected in different shapes i.e. circular, square,
and elliptical as well as in different configurations i.e. with and without fins. All the geometries
of PCMHE modeled in Solid Works saves in IGES format and transported in the Ansys Fluent to
convert them into finite element models by mesh generation of the geometries. Unstructured
triangular elements are used for the mesh generation of all the geometries of PCMHE.
After the mesh generation is completed, the meshed model is transferred to the Ansys Fluent
setup and solution mode. In the setup mode of Ansys Fluent, further operations like solver type,
time dependency, gravitational acceleration, material properties, boundary conditions, etc. are
selected and then the solution is executed. 2D CFD numerical investigation of heat transfer &
melting of PCM in different geometries of PCMHE has been performed. After the execution of
the solution of all geometries of PCMHE has been completed, viewing and postprocessing of the
results are performed.
CFD investigations of heat exchanger geometries have been performed at different temperatures
for liquid fraction and mean temperature of PCM as well as melting time and time for attainment
of applied temperature. Results show that enhancement of heat transfer and reduction in melting
time take place by employing a number of fins on tubes of PCMHE. It has also been concluded
by comparing the different geometries of PCMHE that the configuration having the similar shape
of shell and tubes (both shell and tubes are either square or circular) has the maximum heat
transfer rate and lowest melting time compared to other geometries of PCMHE. Based on the
available simulation data, the findings are validated and show good agreement, which suggests a
deviation of 3.8 & 4.1 percent.
3
KUMAR, NITIN. "PERFORMANCE ANALYSIS OF LATENT HEAT THERMAL ENERGY STORAGE SYSTEM USING FINS". Thesis, 2023. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19964.
Testo completoAbstract (sommario):
The Purpose of the current work is to examine the performance of a PCM i.e. phase
change material within a Trapezoidal shape unit to store heat energy. The Numerical
simulation is done using ANSYS 22 software to simulate and analyze the results,
focusing on temperature and time contours throughout melting part and solidification
part of PCM. Storage unit features a square shape tube in which fins are attached to the
tube to study the HTR. One main challenge encountered in PCM melting is the
collection of solid material at the lowermost in a process of charging and LF rests at the
uppermost during the process of discharging. The numerical simulation explains the
temperature distribution across various ranges during the melting and solidification
phases. The system's effectiveness and performance are enhanced by using this setup.
The simulation's results show that throughout the melting process, the liquid percentage
rapidly grows, reaching 78% during the first 250 minutes. This is because heat is
transferred through convection and conduction. However, after then, heat is transferred
primarily through conduction, which results in a decline in the rate of liquid fraction
and a total melting time of 2390 minutes for the PCM. In a similar manner, following
the first 250 minutes of discharge, the solid percentage increases more slowly,
solidifying to about 34%. However, it takes 1660 minutes for the PCM to fully solidify.
The study's finding show that using a trapezoidal form geometry and including fins may
enhance the melting and solidification part for a TESs.
Capitoli di libri sul tema "LHTES SYSTEM"
1
Agrawal, Abhishek, e Dibakar Rakshit. "Review on Thermal Performance Enhancement Techniques of Latent Heat Thermal Energy Storage (LHTES) System for Solar and Waste Heat Recovery Applications". In New Research Directions in Solar Energy Technologies, 411–38. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0594-9_15.
Testo completoAtti di convegni sul tema "LHTES SYSTEM"
1
Chirino, Hermes, e Ben Xu. "Comprehensive Parametric Analysis and Sensitivity Study of Latent Heat Thermal Energy Storage System in Concentrated Solar Power Plants". In ASME 2018 12th International Conference on Energy Sustainability collocated with the ASME 2018 Power Conference and the ASME 2018 Nuclear Forum. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/es2018-7437.
Testo completoAbstract (sommario):
Compared to Solar Photovoltaics (PV), Concentrated Solar Power (CSP) can store the excess solar thermal energy, extend the power generation at night and cloudy days, and levelize the mismatch between energy demand and supply. To make CSP competitive, Thermal Energy Storage (TES) system filled with phase change material (PCM) is a promising indirect energy storage technique, compared to the TES system using concrete or river rocks. It is of great interests to solar thermal community to apply the latent heat thermal energy storage (LHTES) system for large scale CSP application, because PCMs can store more thermal energy due to the latent heat during the melting/freezing process. Therefore, a comprehensive parametric analysis of LHTES system is necessary in order to improve its systematic performance, since LHTES system has a relatively low energy storage efficiency compared to TES systems using sensible materials. In this study, an 11-dimensionless-parameter space of LHTES system was developed, by considering only the technical constraints (materials properties and operation parameters), instead of economic constraints. Then the parametric analysis was performed based on a 1D enthalpy-based transient model, and the energy storage efficiency was used as the objective function to minimize the number of variables in the parameter space. It was found that Stanton number (St), PCM radius (r), and void fraction (ε) are the three most important ones. The sensitivity study was conducted then based on the three dimensionless-parameter space which will significantly influence the system performance. The results of this study make LHTES system competitive with TES system using sensible materials in terms of energy storage efficiency.
2
Sciacovelli, Adriano, Elisa Guelpa e Vittorio Verda. "Second Law Analysis of Tree-Shaped Fins for the Heat Transfer Enhancement in a PCM Thermal Storage System". In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65105.
Testo completoAbstract (sommario):
Latent heat thermal energy storage (LHTES) systems based on phase change materials (PCMs) are a promising option to be employed as effective energy storage devices. PCM allows one to achieve high energy storage density and almost constant temperature energy retrieval, however LHTES systems performance is limited by poor thermal conductivity of the PCMs which leads to unacceptably low melting and solidification rates. Thus, heat transfer enhancement techniques are required in order to obtain acceptable melting and solidification rates. The preliminary design of a shell-and-tube LHTES unit is investigated by means of computational fluid-dynamics (CFD). Three different fin designs are considered: a conventional radial fin, a constructal Y-shaped fin design and a non-constructal Y-shaped configuration previously investigated by the authors. The performances of each fin configuration are evaluated by means of a Second-law analysis. Moreover, local and global entropy generation rates are analyzed in order to show the main source of thermodynamic irreversibilities occurring in the system. The analysis indicates that solidification rate is significantly enhanced when Y-shaped fins are adopted in the LHTES unit, however the constructal Y-shaped geometry is not optimal since further improvements can be achieved by means of a Y-shaped fins with elongated secondary branches.
3
Buonomo, Bernardo, Oronzio Manca, Sergio Nardini e Renato Elpidio Plomitallo. "Numerical Investigation on Shell and Tube Latent Thermal Energy Storage Partially Filled With Metal Foam and Corrugated Internal Tube". In ASME 2022 Heat Transfer Summer Conference collocated with the ASME 2022 16th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/ht2022-81806.
Testo completoAbstract (sommario):
Abstract A numerical investigation on Latent Heat Thermal Energy Storage System (LHTESS), based on a phase change material (PCM) partially filled with metal foam, is accomplished. The geometry of the system is a vertical shell and tube LHTES made with two concentric aluminum tubes with the internal tube corrugated. The corrugated internal surface of the hollow cylinder is assumed at a constant temperature above the melting temperature of the PCM to simulate the heat transfer from a hot fluid. The other external surfaces are assumed adiabatic. The phase change of the PCM is modelled with the enthalpy porosity theory while the metal foam is considered as a porous media that obeys to the Darcy-Forchheimer law. Local thermal equilibrium (LTE) model is assumed to analyze the metal foam. Numerical simulations for PCM and PCM in the porous medium in LTE assumptions are obtained and their results are compared in terms of melting time, temperature fields and energy stored. The results show that the heat transfer in the LHTES system improves giving a very faster phase change process when the presence of metal foam increases.
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Buonomo, Bernardo, Davide Ercole, Oronzio Manca, Hasan Celik e Moghtada Mobedi. "Numerical Investigation on the Effect of Aluminum Foam in a Latent Thermal Energy Storage". In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53180.
Testo completoAbstract (sommario):
In this paper, a numerical investigation on Latent Heat Thermal Energy Storage System (LHTESS) based on a phase change material (PCM) is accomplished. The geometry of the system under investigation is a vertical shell and tube LHTES made with two concentric aluminum tubes. The internal surface of the hollow cylinder is assumed at a constant temperature above the melting temperature of the PCM to simulate the heat transfer from a hot fluid. The other external surfaces are assumed adiabatic. The phase change of the PCM is modeled with the enthalpy porosity theory while the metal foam is considered as a porous media that obeys to the Darcy-Forchheimer law. The momentum equations are modified by adding of suitable source term which it allows to model the solid phase of PCM and natural convection in the liquid phase of PCM. Both local thermal equilibrium (LTE) and local thermal non-equilibrium (LTNE) models are examined. Results as a function of time for the charging phase are carried out for different porosities and assigned pore per inch (PPI). The results show that at high porosity the LTE and LTNE models have the same melting time while at low porosity the LTNE has a larger melting time. Moreover, the presence of metal foam improves significantly the heat transfer in the LHTES giving a very faster phase change process with respect to pure PCM, reducing the melting time more than one order of magnitude.
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Shabgard, Hamidreza, Amir Faghri, Theodore L. Bergman e Charles E. Andraka. "Numerical Simulation of Heat Pipe-Assisted Latent Heat Thermal Energy Storage Unit for Dish-Stirling Systems". In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-65487.
Testo completoAbstract (sommario):
A two-dimensional model is developed to simulate the transient response of a heat pipe-assisted latent heat thermal energy storage (LHTES) unit that is combined with dish-Stirling solar power generation systems. The unit consists of a container which houses a phase change material (PCM) and two sets of interlaced input and output heat pipes (HPs) embedded in the PCM. The LHTES unit is exposed to time-varying concentrated solar irradiance. A three-stage operating scenario is investigated that includes: (i) charging only, (ii) simultaneous charging and discharging, and (iii) discharging only. In general, it was found that the PCM damps the temporal variations of the input solar irradiance, and provides relatively smooth thermal power to the engine over a time period that can extend to after-sunset hours. Heat pipe spacing was identified as a key parameter to control the dynamic response of the unit. The system with the greatest (smallest) heat pipe spacing was found to have the greatest (smallest) temperature drops across the LHTES, as well as the maximum (minimum) amount of PCM melting and solidification. Exergy analyses were also performed, and it was found that the exergy efficiencies of all the systems considered were greater than 97%, with the maximum exergy efficiency associated with the system having the minimum heat pipe spacing.
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Urschitz, Georg, Heimo Walter e Michael Hameter. "Experimental Investigation of a Finned Mono Tube — Latent Heat Thermal Energy Storage (LHTES)". In ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6338.
Testo completoAbstract (sommario):
The present experimental investigation covers the construction of a latent heat thermal energy storage system (LHTES), which uses sodium nitrate (NaNO3) as phase change material (PCM). The storage unit is filled with 300 kg of the PCM. For the heat transfer a vertically arranged bimetallic mono tube with longitudinal fins is used. The fins increase the heat flux into/from the PCM. Thermal oil is used as a heat transfer medium, as it allows working temperatures up to 400°C. This thermal energy storage is able to store 60 kWh of thermal energy and can be loaded with a power up to 200 kW. One part of the investigation results presented in this paper was the determination of the storable energy and the comparison with data from literature and calculations. Additionally, the melting behavior of the PCM was measured with temperature sensors located at different positions over the height of the storage unit. Finally, the entrance of the heat transfer medium was changed from the top to the bottom of the thermal energy storage unit and a different melting behavior could be detected.
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Liu, Fang, Hao Liang, Hang Yu e Xiaomei Tang. "Research Development and Application of Solar Thermal Storage With Phase Change Materials". In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90331.
Testo completoAbstract (sommario):
Research on efficient and economical thermal storage technology becomes common issue to the scholars. Especially research on PCMs becomes hot spot these years. In view of the discontinuity and instability of solar energy, efficient and economic research on energy storage technology occupies a very important position. This article summarizes and evaluates the research development and applications of solar thermal storage technology with PCMs both in China and the other countries. Including four parts: A review on preparation of new composite phase change materials and its thermophysical properties was carried out. Various heat transfer enhancement technology was overviewed. Including adding metal fill, adding graphite, capsule package, plus fins, adding carbon fiber and composite phase change materials, etc. Mathematical modeling of a latent heat thermal energy storage system (LHTES) was reviewed in recent years which is used for the optimum material selection and to assist in the optimal designing of the systems. The important characteristics of different models and their assumptions used are presented and discussed, the experimental validation of some models are also presented. The applications and prospects of PCMs used in the different fields were summarized, such as industry, agriculture, construction, textiles, electronic products, medicine, transportation etc. Finally, conclusions and perspectives were drawed. Hope to provide references to the other researchers in this field.
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Xu, Ben, Yawen Zhao, Hermes Chirino e Peiwen Li. "Parametric Study of Cascade Latent Heat Thermal Storage System for Concentrating Solar Power Plants". In ASME 2017 11th International Conference on Energy Sustainability collocated with the ASME 2017 Power Conference Joint With ICOPE-17, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/es2017-3096.
Testo completoAbstract (sommario):
Recently, Concentrated Solar Power (CSP) is attracting more research attentions because it can store the excessive heat from the solar field and extend the power generation at night, CSP can also levelized the mismatch between energy demand and supply. To make CSP technology competitive, thermal energy storage (TES) system filled with energy storage media is a critical component in all CSP plant. TES system can be operated by using sensible materials, phase change materials (PCMs) or a combination of both. Because the phase change materials can store more heat due to the latent during the melting/freezing process, it becomes promising to use PCM in latent heat thermal energy storage (LHTES) system for large scale CSP application. Unfortunately, LHSS has relatively low energy storage efficiency compared to SHSS alone because of the fact that LHSS has more parameters to be controlled and optimized. To realize a complete utilization of PCM and a high energy storage/extraction efficiency and a high exergetic efficiency, one approach is to adopt a cascade configuration of multiple PCMs modules in TES tank, which can also be called as a cascade latent heat thermal energy storage (CLHTES) system. The melting temperatures of the PCMs placed in the TES tank should be cascaded from low to high temperature, where the latent heat of PCM can completely be used to absorb the heat from the solar field for energy storage purpose. Due to the complexity of a CLHTES system, it is necessary to provide a comprehensive study from the heat transfer perspective. This paper presents a preliminary parametric study of CLHTES system using a previously developed enthalpy-based 1D transient model for energy storage/extraction in CLHTES system. The effects of material properties (such as latent heat, specific heat at solid and liquid phase) and CSP plant operation conditions (such as charging/discharging time period) are to be explored. The results from the preliminary parametric study is expected to be beneficial to the community of solar thermal engineering.
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Hockins, Addison, Samantha Moretti, Mahboobe Mahdavi e Saeed Tiari. "Experimental and Numerical Study of a Latent Heat Thermal Energy Storage Unit Enhanced by Fins". In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24024.
Testo completoAbstract (sommario):
Abstract Latent heat thermal energy storage (LHTES) systems are used to store thermal energy and release it for later use by melting or solidifying a phase change material (PCM). One problem associated with latent heat thermal energy storage systems is the low thermal conductivity of most commercially aviable phase change materials. This can have a significant negative effect on the thermal performance of the system by leading to a longer charging or discharging process. Several passive heat transfer enhancement techniques are used to resolve this issue. Common passive heat transfer enhancement techniques include inserting fins and extended surfaces into the PCM, embedding heat pipes or other two-phase heat transfer devices within the PCM, dispersion of highly conductive nanoparticles in the PCM, and impregnation of highly conductive porous media with the PCM. The current study analyzes the effect of a fin-based enhancement technique on the thermal performance of a latent heat thermal energy storage unit. Copper fins are attached annually around the central pipe inside the PCM. A transient two-dimensional numerical model technique is developed using ANSYS FLUENT 19.0 to simulate the operation of the system. Baseline tests have been conducted experimentally for a system without fins to validate the numerical model. The results obtained from the numerical modeling are in good agreement with those of the experimental testing. Based on the experimental testing, the total charging time of the system using hot water at 70°C and flow rate of 7.57 L/min is around 47.9 hours which is very close to the prediction by the numerical model which is 48 hours. Numerical modeling of the system with 10 fins and 20 fins found that the charging time was decreased by 68.9% and 73.7%, respectively. The discharging time was also decreased by 73.2% and 79.1%, respectively.
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Myers, Philip D., Abhinav Bhardwaj, D. Yogi Goswami e Elias Stefanakos. "Chloride Salt Systems for High Temperature Thermal Energy Storage: Properties and Applications". In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49460.
Testo completoAbstract (sommario):
There is substantial potential to increase the operating temperatures of concentrating solar power (CSP) plants, thereby increasing the Carnot efficiency. Coupled with viable thermal energy storage (TES) strategies, this would bring us closer to achieving the goals of the U.S. Department of Energy Sunshot Initiative. Current TES media employ molten inorganic salts (namely, nitrate salts) for thermal storage, but they are limited in application to lower temperatures: generally, below 600°C. While sufficient for parabolic trough power plants, these materials are inadequate for use with the higher operating temperatures achievable in solar power tower-type CSP plants. For these higher temperatures, chloride salts are more ideal candidate storage media, either for sensible heat storage in the molten salt (e.g, a dual-tank storage arrangement) or for sensible and latent heat thermal energy storage (LHTES) as phase change materials (PCMs). Their melting points and those of their eutectic mixtures cover a broad range of potential operating temperatures, up to and including 800.7°C, the melting point of pure NaCl. This paper examines these salt systems and presents relevant properties and potential applications in high temperature (>400°C) utility scale solar thermal power generation. A preliminary screening of pure chloride salts based on available literature yields a list of promising candidate salts. Eutectic mixtures of these salts are also considered; the eutectic systems were modeled using the thermodynamic database software, FactSage. Thermophysical properties (melting point, latent heat) are summarized for each salt system. Radiative properties are also addressed, since at these temperatures, thermal radiation can become a significant mode of heat transfer. Candidate containment materials and strategies are discussed, along with the attendant potential for corrosion. Finally, cost data for these systems are presented, allowing for meaningful comparison among these systems and other materials in the context of utility scale thermal energy storage units.