scholarly journals EXPERIMENTAL RESEARCH OF THERMAL STABILITY OF SUBSTANCES FOR THERMAL ENERGY STORAGE

2019 ◽  
Vol 41 (2) ◽  
pp. 64-71
Author(s):  
V.G. Demchenko ◽  
V.Yu Falco
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Melting Point ◽  
Thermal Energy ◽  
Thermophysical Properties ◽  
Heat Storage ◽  
Waste Heat ◽  
Thermal Power ◽  
Stable Operation ◽  
Heating And Cooling

Optimizing the storage methods for excess heat energy and associated technical and technological solutions has a significant impact on the development of LHTES systems. New technologies for storing thermal energy are increasingly an alternative to the classic methods of providing thermal infrastructure facilities. In this paper we analyze the results of experimental studies of heat-storage materials for their further integration into the Smart Grid heating system of infrastructure objects and use in the M-TES. The conducted literary review showed that the thermophysical parameters of the investigated substances for the conservation of heat from different authors are very different. We conclude that this is due to the quality of the materials being studied and the errors of laboratory measurements. This negatively affects the design of LHTES systems and greatly complicates the calculation and modeling of heat transfer processes. It is especially important to correctly determine the amount of heat that can be obtained during the charging and discharge cycles of TES, as well as the lifetime of the material that accumulates heat. Therefore, the purpose of this work is to identify the appropriate material for energy storage applications between 0 0C and 115 0C and evaluate it, depending on the thermophysical properties and the time of stable operation. Taking into account the economic aspects, only the available technical materials are considered within the framework of this study, since the choice of material is aimed at the use of M-TES in real conditions of operation. Figure 1 summarizes the results of research on heating and cooling cycles of heats of heat storage substances. High thermal power and, hence, high thermal conductivity are important for the storage efficiency of PCM, especially in the process of solidification, because in a heat transfer predominant solid layer that grows continuously. However, both PCMs are not suitable for mobile thermal storage systems in this form. The huge disadvantages are the emergence of different values ​​of the melting point, the high retention time of both candidates, as well as their prices. Therefore, further research should be directed to eliminate these negative effects. Despite the relatively low density of heat storage with aqueous solutions of antifreeze, they are beneficial candidates for waste heat transfer systems within the framework of this study. Addition of NaCl salt practically does not affect the speed of heating and cooling of the coolant. The addition of bischofite worsens the thermophysical properties of water and shows a small density of heat accumulation. It has been experimentally established that after 3 ... 4 cycles of heating and cooling from a solution of technical bischofite, a dark yellow, insoluble precipitate forms, which creates problems during the operation. Significant increase in TES discharge time was obtained when testing ozokerite. All of the above substances have shown a stable state after 30 cycles of heating / cooling and indicate overcooling below the melting point by about 30 °C. Trihydrate sodium acetate shows no stable results. Subsequently, after 20 cycles of heating and cooling, it loses its properties.

Latent Heat Storage: Container Geometry, Enhancement Techniques, and Applications—A Review

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
S. Arunachalam
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Low Thermal Conductivity

Energy storage helps in waste management, environmental protection, saving of fossil fuels, cost effectiveness, and sustainable growth. Phase change material (PCM) is a substance which undergoes simultaneous melting and solidification at certain temperature and pressure and can thereby absorb and release thermal energy. Phase change materials are also called thermal batteries which have the ability to store large amount of heat at fixed temperature. Effective integration of the latent heat thermal energy storage system with solar thermal collectors depends on heat storage materials and heat exchangers. The practical limitation of the latent heat thermal energy system for successful implementation in various applications is mainly from its low thermal conductivity. Low thermal conductivity leads to low heat transfer coefficient, and thereby, the phase change process is prolonged which signifies the requirement of heat transfer enhancement techniques. Typically, for salt hydrates and organic PCMs, the thermal conductivity range varies between 0.4–0.7 W/m K and 0.15–0.3 W/m K which increases the thermal resistance within phase change materials during operation, seriously affecting efficiency and thermal response. This paper reviews the different geometry of commercial heat exchangers that can be used to address the problem of low thermal conductivity, like use of fins, additives with high thermal conductivity materials like metal strips, microencapsulated PCM, composite PCM, porous metals, porous metal foam matrix, carbon nanofibers and nanotubes, etc. Finally, different solar thermal applications and potential PCMs for low-temperature thermal energy storage were also discussed.

scholarly journals Optimal Design of Combined Two-Tank Latent and Metal Hydrides-Based Thermochemical Heat Storage Systems for High-Temperature Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4216 ◽  
Author(s):  
Serge Nyallang Nyamsi ◽  
Mykhaylo Lototskyy ◽  
Ivan Tolj
Keyword(s):  
Energy Storage ◽  
Melting Point ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Heat Storage ◽  
Waste Heat ◽  
Storage Systems ◽  
Storage System ◽  
Metal Hydrides ◽  
Thermochemical Heat Storage

The integration of thermal energy storage systems (TES) in waste-heat recovery applications shows great potential for energy efficiency improvement. In this study, a 2D mathematical model is formulated to analyze the performance of a two-tank thermochemical heat storage system using metal hydrides pair (Mg2Ni/LaNi5), for high-temperature waste heat recovery. Moreover, the system integrates a phase change material (PCM) to store and restore the heat of reaction of LaNi5. The effects of key properties of the PCM on the dynamics of the heat storage system were analyzed. Then, the TES was optimized using a genetic algorithm-based multi-objective optimization tool (NSGA-II), to maximize the power density, the energy density and storage efficiency simultaneously. The results indicate that the melting point Tm and the effective thermal conductivity of the PCM greatly affect the energy storage density and power output. For the range of melting point Tm = 30–50 °C used in this study, it was shown that a PCM with Tm = 47–49 °C leads to a maximum heat storage performance. Indeed, at that melting point narrow range, the thermodynamic driving force of reaction between metal hydrides during the heat charging and discharging processes is almost equal. The increase in the effective thermal conductivity by the addition of graphite brings about a tradeoff between increasing power output and decreasing the energy storage density. Finally, the hysteresis behavior (the difference between the melting and freezing point) only negatively impacts energy storage and power density during the heat discharging process by up to 9%. This study paves the way for the selection of PCMs for such combined thermochemical-latent heat storage systems.

scholarly journals Review of solid particle materials for heat transfer fluid and thermal energy storage in solar thermal power plants

2019 ◽  
Vol 1 (4) ◽  
Author(s):  
Alejandro Calderón ◽  
Camila Barreneche ◽  
Anabel Palacios ◽  
Mercè Segarra ◽  
Cristina Prieto ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Solid Particle ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Thermal Power ◽  
Heat Transfer Fluid ◽  
Thermal Power Plants ◽  
Solar Thermal Power

Numerical Investigation of Combined Sensible/Latent Heat Thermal Energy Storage With Supercritical Carbon Dioxide As Heat Transfer Fluid at 650°C

2019 ◽  
Author(s):  
Kelly Osterman ◽  
Diego Guillen ◽  
D. Yogi Goswami
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Energy Storage ◽  
Supercritical Carbon Dioxide ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Dry Air

Abstract This paper numerically explores a high-temperature sensible-latent hybrid thermal energy storage system designed to store heat with output temperatures stabilized at approximately 550–600 °C for direct coupling with supercritical carbon dioxide (sCO2) power cycles operating at their design point. sCO2 and dry air at 25 MPa are used as heat transfer fluid (HTF) in a packed bed storage system that combines rocks as sensible heat storage and AlSi12 as latent heat storage. The base model using dry air at atmospheric pressure is compared to similar work done at ETH Zurich; the model is then extended for use with sCO2 to compare the performance of air and sCO2 at similar volumetric flow rates. It was found that sCO2 is capable of storing a significantly larger amount of energy (∼40 kWh) in the same time period as the air system (∼19 kWh), and can discharge that energy much quicker (1.5 hours compared to 4 hours). However, in order to achieve similar degrees of temperature stabilization, the total height of PCM had to be increased significantly, from 9 cm to 45 cm or more.

scholarly journals Recent Investigations of Phase Change Materials Use in Solar Thermal Energy Storage System

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Qianjun Mao ◽  
Ning Liu ◽  
Li Peng
Keyword(s):  
Energy Storage ◽  
Melting Point ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Solar Thermal Energy ◽  
Temperature Heat

Solar thermal energy storage (TES) is an efficient way to solve the conflict between unsteady input energy and steady output energy in concentrating solar power plant. The latent heat thermal energy storage (LHTES) system is a main method of storing thermal energy using phase change materials (PCMs). Thermal properties, that is, melting points and latent heat, are the key parameters of PCMs for the TES system. In this paper, the PCMs are classified into inorganic and organic by the chemical composition, and according to the melting point, the inorganic PCMs can be divided into three contributions: low-temperature heat storage (less than 120°C), medium-temperature heat storage (120–300°C), and high-temperature heat storage (more than 300°C). The present article focuses mainly on the recent investigations on the melting point and latent heat of PCMs via DSC setup in the solar TES systems. The results can provide a good reference for the selection and utilization of PCMs in the solar TES systems.

scholarly journals Towards development of a prototype high-temperature latent heat storage unit as an element of a RES-based energy system (part 2)

2016 ◽  
Vol 64 (2) ◽  
pp. 401-408
Author(s):  
J. Karwacki ◽  
K. Bogucka-Bykuć ◽  
W. Włosiński ◽  
S. Bykuć
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Heat Transfer Fluid ◽  
Storage Unit ◽  
Latent Heat Storage ◽  
Shell And Tube

Abstract This paper presents an experimental study performed with the general aim of defining procedures for calculation and optimization of shell-and-tube latent thermal energy storage unit with metals or metal alloys as PCMs. The experimental study is focused on receiving the exact information about heat transfer between heat transfer fluid (HTF) and phase change material (PCM) during energy accumulation process. Therefore, simple geometry of heat transfer area was selected. Two configurations of shell-and-tube thermal energy storage (TES) units were investigated. The paper also highlights the emerging trend (reflected in the literature) with respect to the investigation of metal PCM-based heat storage units in recent years and shortly presents unique properties and application features of this relatively new class of PCMs.

scholarly journals PENGGUNAAN PARAFFIN WAX SEBAGAI PENYIMPAN KALOR PADA PEMANAS AIR TENAGA MATAHARI THERMOSYPHON

ROTASI ◽  
2016 ◽  
Vol 18 (3) ◽  
pp. 76 ◽  
Author(s):  
Muhammad Nadjib
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Sensible Heat ◽  
Latent Heat Storage ◽  
Change Material

Pemanas Air Tenaga Matahari (PATM) konvensional umumnya menggunakan air sebagai penyimpan energi termal. Pemakaian sensible heat storage (SHS) ini memiliki kekurangan, diantaranya adalah densitas energinya rendah. Di sisi lain, latent heat storage (LHS) mempunyai sifat khas yaitu densitas energinya tinggi karena melibatkan perubahan fasa dalam penyerapan atau pelepasan kalor. Material LHS sering disebut phase change material (PCM). Penggunaan PCM pada PATM menarik dilakukan untuk meningkatkan densitas energi sistem. Penelitian ini bertujuan untuk menyelidiki perilaku termal penggunaan paraffin wax di dalam tangki PATM jenis thermosyphon. Penelitian menggunakan kolektor matahari pelat datar dan tangki thermal energy storage (TES) yang dipasang secara horisontal di sisi atas kolektor. Di dalam tangki terdapat alat penukar kalor yang terdiri dari sekumpulan pipa kapsul dimana di dalamnya berisi paraffin wax. Air digunakan sebagai SHS dan heat transfer fluid (HTF). Termokopel dipasang di sisi HTF dan sisi PCM. Piranometer dan sensor temperatur udara luar diletakkan di dekat kolektor matahari. Pengambilan data dilakukan selama proses charging. Temperatur HTF, PCM dan intensitas radiasi matahari direkam setiap 30 detik. Data ini digunakan untuk mengetahui evolusi temperatur HTF dan PCM. Berdasarkan evolusi temperatur ini kemudian dianalisis perilaku termal PATM. Hasil dari penelitian ini adalah bahwa paraffin wax telah berfungsi sebagai penyimpan energi termal bersama air di dalam tangki PATM jenis thermosyphon. PCM memberi kontribusi yang cukup signifikan terhadap kapasitas penyimpanan energi sistem. Efisiensi kolektor lebih optimal karena PCM dapat mempertahankan stratifikasi termal sampai akhir charging. Adanya PCM mampu mengendalikan penurunan efisiensi pengumpulan energi saat intensitas radiasi matahari menurun. Alat penukar kalor yang digunakan cukup efektif yang ditandai dengan kecepatan pemanasan rata-rata antara HTF dan PCM yang tidak berbeda jauh.

scholarly journals Numerical Evaluation of the Transient Performance of Rock-Pile Seasonal Thermal Energy Storage Systems Coupled with Exhaust Heat Recovery

2020 ◽  
Vol 10 (21) ◽  
pp. 7771
Author(s):  
Leyla Amiri ◽  
Marco Antonio Rodrigues de Brito ◽  
Seyed Ali Ghoreishi-Madiseh ◽  
Navid Bahrani ◽  
Ferri P. Hassani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Waste Heat ◽  
Fluid Velocity ◽  
Transfer Model ◽  
Mining Operations ◽  
Exhaust Heat ◽  
Wide Range

This study seeks to investigate the concept of using large waste rocks from mining operations as waste-heat thermal energy storage for remote arctic communities, both commercial and residential. It holds its novelty in analyzing such systems with an experimentally validated transient three-dimensional computational fluid dynamics and heat transfer model that accounts for interphase energy balance using a local thermal non-equilibrium approach. The system performance is evaluated for a wide range of distinct parameters, such as porosity between 0.2 and 0.5, fluid velocity from 0.01 to 0.07 m/s, and the aspect ratio of the bed between 1 and 1.35. It is demonstrated that the mass flow rate of the heat transfer fluid does not expressively impact the total energy storage capacity of the rock mass, but it does significantly affect the charge/discharge times. Finally, it is shown that porosity has the greatest impact on both fluid flow and heat transfer. The evaluations show that about 540 GJ can be stored on the bed with a porosity of 0.2, and about 350 GJ on the one with 0.35, while the intermediate porosity leads to a total of 450 GJ. Additionally, thermal capacity is deemed to be the most important thermophysical factor in thermal energy storage performance.

A Hybrid Decision-Making Method for the Selection of a Phase Change Material for Thermal Energy Storage

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Uma Maheswararao Gaddala ◽  
Jaya Krishna Devanuri
Keyword(s):  
Thermal Stability ◽  
Decision Making ◽  
Energy Storage ◽  
Low Temperature ◽  
Thermal Energy ◽  
Thermophysical Properties ◽  
Heat Storage ◽  
Temperature Heat ◽  
Selection Of ◽  
Melting And Solidification

Abstract Phase change materials (PCMs) are considered to be promising contenders for thermal energy storage (TES) due to their high latent heat and nearly constant temperature during the intake/release of heat. The present study focuses on providing the most suitable PCM for low-temperature (40–80 °C) heat storage applications. However, the selection of the most suitable one from the wide range of PCMs for an application needs a thorough insight of their thermophysical properties, thermal stability, compatibility, and melting and solidification behavior. Among the PCMs available for low-temperature heat storage applications, organic PCMs stand as an attractive option. Based on melting point temperature, latent heat, cost, and ease of availability, five widely used organic PCMs, viz., lauric acid (LA), myristic acid (MA), stearic acid (SA), paraffin wax (PW), and palmitic acid (PA), are selected. Initially, thermophysical properties are measured and tabulated. Subsequently, thermal stability experiments up to 1500 melting/freezing cycles, compatibility studies with container materials (aluminum and stainless steel (SS)), and melting and solidification experiments giving total melting and solidification times are performed. Further, a hybrid multiple attribute decision-making (MADM) method is employed to select the best PCM based on the obtained experimental results. During the selection process at first, the subjective weights of the attributes are measured according to the analytical hierarchy process (AHP). Later, the PCMs are ranked based on the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The hybrid MADM results show that among the selected PCMs, paraffin wax is the optimal PCM for low-temperature heat storage applications.

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