Heat Discharge Research Articles

Smoothing cooling demand of buildings with PCM thermal batteries

Escalating energy tariffs and peak cooling demands due to climate change along with expanding use of variable renewable energy supply are presenting new challenges and opportunities for air conditioning system operation and control. This research presents the outcome of an investigation into the use of a thermal battery using salt-hydrate phase change material (PCM) in commercial buildings. A 1.2 m3 modular thermal battery using 15 °C melting temperature salt-hydrate PCM has been designed and fabricated. Its cooling performance and feasibility of integration into a chilled water-cooling system of commercial buildings has been comprehensively investigated. This storage unit can accommodate approximately 52 kWh of energy, featuring a rapid heat discharge rate of 32.58 kW during the initial 30 min to effectively address sudden cooling demands. The overall heat discharge rate closely aligns with simulation results, reaching approximately 96% accuracy. This has been achieved through optimisation of the heat exchanger design through mathematical simulation, detailed testing to match various operational scenarios and evaluation of economic and peak load shifting benefits. The results demonstrate the environmental and economic effectiveness of the PCM thermal battery as an independent component in building cooling systems. It provides a timely response to peak cooling demand and improves thermal comfort of the buildings.

Experimental research on off-design characteristics of heat pump water heater using low GWP zeotropic blend

Based on the test setup of instant heat pump water heater (IHPWH), the performances of system operating with zeotropic natural mixture (ZNM) (R744/R290 (12/88)) and system operating with R22 refrigerant were compared under variable entry temperature of heat sink (ETHSK) and variable entry temperature of heat source (ETHSC) conditions, aiming to comprehensively evaluate the replacement potential of ZNM in the IHPWH. The results revealed that ZNM had an obvious alternative advantage, mainly attributed to that system operating with ZNM refrigerant achieved the comparable or markedly superior heating capacity and COP and markedly lower discharge temperature compared to those of system operating with R22 refrigerant under two conditions. The discharge temperature of system operating with ZNM refrigerant was reduced by 5.4~26.7? compared to that of system operating with R22 refrigerant, thus system operating with ZNM refrigerant can produce higher temperature domestic hot water. Compared with those of system operating with R22 refrigerant, both heating capacity and COP of system operating with ZNM refrigerant had markedly different trends with the change of ETHSK, while they had slightly different trends with the change of ETHSC. Compared to the ETHSK, the ETHSC has a more conspicuous impact on the heating capacity, COP and discharge temperature of system operating with ZNM refrigerant.

Effects of air gap and compression on the dual performance of multilayer thermal protective clothing under low radiant heat

An air gap in thermal protective clothing (TPC) plays an important role in determining heat transfer, but it may also increase the amount of stored thermal energy that would discharge to the skin after exposure, especially when the TPC suffers compression. To investigate the effect of air gap and compression on the dual thermal protective performance (TPP), thermal hazardous performance (THP) and overall thermal protective performance (OTPP) of TPC, nine air gap configurations with different sizes and positions and five compression levels were designed in this study. Regression models were established to explore the relationships among air gap size, compression and THP for different air gap positions. The results demonstrate that increasing the air gap size without exceeding 12 mm not only significantly enhances the TPP by impeding heat transfer from the heat source to the fabric system during exposure but also decreases the THP by reducing heat discharge from the fabric system to the sensor even when compression is applied. Although an inner air gap contributes more to increasing the TPP during exposure than an outer air gap, it may also bring about severe stored energy discharge when compression is applied. It suggests that a larger air gap size should be divided into individually separate air gaps within different fabric layers to reduce the heat transfer during exposure as well as lower the stored thermal energy discharge after exposure.

Full-scale three-dimensional simulation of air cooling metal bipolar plate proton exchange membrane fuel cell stack considering a non-isothermal multiphase model

Addressing issues such as the mass transfer characteristics and internal performance consistency of the air cooling (AC) proton exchange membrane fuel cell (PEMFC) stack. A full-scale AC metal bipolar plate (BP) stack is proposed in this study, comprising inlet and outlet manifolds, membrane electrode assembly (MEA), reaction flow field (FF) and cooling FF. The coupling of electrochemical reactions and heat and mass transfer processes in the stack is simulated using a non-isothermal multiphase numerical model. The characterization of the mass spatial distribution in the stack is explored by varying the stoichiometric ratio of the cathode gas, the thermal boundary conditions, the flow direction of the reaction gas and the air inlet flow configuration. According to the simulation results, it is found that, initially, the simulation errors in the one-dimensional (1D) AC stack are large and mainly concentrated in the concentration loss region. Subsequently, the increased stoichiometric ratio enhances the proton exchange membrane (PEM) water content, improves the local current density by 1.6% and facilitates the discharge of waste heat from the stack. Furthermore, thermal boundary conditions significantly affect the distribution of temperature uniformity in the stack, with high local temperatures causing significant water vapor generation and resulting in oxygen dilution. The counter-flow of hydrogen and air enhances the electrochemical reaction rates in the cathode catalyst layer (CCL) by 0.353%, with the lowest liquid water content in the seventh cell, influenced by the uneven distribution of manifold flow. Finally, changing the position of the cathode manifold gas inlet indicates that the positive flow of the cathode and AC inlets from the Z axis reduces the maximum stack temperature and water vapor by 1.04% and 0.38% respectively. The CCLs in Case 4 have optimal oxygen distribution and output voltages of approximately 0.66 V per fuel cell (FC).

Modelling and simulation of thermal runaway phenomenon in lithium‐ion batteries

AbstractTo improve the operational time of electronic devices and the driving spectra of electric cars, multiple investigation missions regarding batteries are focussed on refining the energy capacity of batteries. However, this pursuit of better performance introduces potential risks, such as fire incidents, due to the use of dynamic materials in lithium‐ion batteries (LIBs) to enhance their electrochemical performance. These fire incidents have resulted in financial losses and raised safety concerns. One common type of battery failure, called thermal runaway (TR), takes place when the rate of heat discharge from internal chain reactions accelerates the level of external cooling. This study aims to model and comprehensively analyse the phenomenon of TR in LIBs by investigating its underlying physics.To conduct this research systematically, a mathematical framework of heat transfer from existing literature has been employed as a foundation to come up with a novel framework specifically for LIBs built on the ideas of Semenov's equation. The established model associates both thermal and mass balance aspects, with the consideration of response kinetics including other heat transfer modes (convective and radiation). Range–Kutta technique is used to unravel the model's equations instantaneously using MATLAB. Consequently, the impact of model factors on the thermal performance of LIBs has been evaluated. The outcomes of the study reveal that when an increase in activation temperature occurs, a decrease in peak temperature is followed whilst constant circumstances are ensured. This implies that more time is needed in order for the temperature to reach its maximum. Furthermore, the simulation demonstrated that any growth in the body capacity of the battery for absorbing heat during the reaction results in a higher maximum temperature. Heat convection is found to have a greater impact on the occurrence of TR in LIBs compared to heat radiation. For improved accuracy in calculating LIBs TR, an accurate kinetic model could be utilised in future research endeavours.

Magnetic dopant and field effects on the heat discharge of organic PCM based lauric acid

In this experimental study, we investigated the heat transfer characteristics during the freezing or heat discharging process of a magnetic-composite phase change material (PCM). Lauric acid (LA) was used as the PCM, Fe3O4and CoFe2O4 were utilised as dopants, and a permanent magnet generated the magnetic field.The time characteristic of freezing data revealed that the magnetic dopant and field increased the heat transfer rate. This improvement resulted in substantial time savings for the solidification process, with a 42% reduction observed for Fe3O4-composite LA and a 33% reduction for CoFe2O4-composite LA. Furthermore, the magnetic field contributed to the reduction in crystal size and crystal growth along the field direction, as observed by digital optical microscopy. The freezing data were correlated with thermal conductivity and viscosity, both strongly depending on the concentration and magnetic field. Their dependence on the magnetic characteristics of the dopant was also evident. The liquid thermal conductivity indicated a critical magnetic field that depends on the dopant type and concentration. For Fe3O4-composite LA and the CoFe2O4-composite LA, the highest liquid thermal conductivity ratios were 121% and 120%, respectively, and these values were achieved at the highest dopant concentration and magnetic field intensity. For small dopant concentrations, the viscosity generally decreased with increasing magnetic field intensity, while for high dopant concentrations, the trend was different. The heat transfer and magneto-viscosity characteristics were closely related to the collaborative effect of magnetic dipolar and magnetic field interactions. The magnetic dopant and field used to control PCM freezing are important factors for optimising the performance of a material as a latent thermal energy storage system.

Heat charging and discharging of coupled MgH2–LaNi5 based thermal storage: Cycling stability and hydrogen exchange reactions

Heat charging and discharging performances and cycling stability of the coupled MgH2–LaNi5 thermal storage system are investigated. Heat storage reaction is studied by tracking temperatures and pressures of hydride beds as well as hydrogen mass flow rates exchanging between MgH2 and LaNi5. Upon 20 heat storage cycles, MgH2–LaNi5 pair reveals remarkably cycling stability with the energy densities during heat charging and discharging of 797 ± 37.5 and 680 ± 28 kJ/kg, respectively. The hydrogen content exchange between MgH2 and LaNi5 during heat storage cycles is up to 57 % of theoretical hydrogen capacity. The possibilities to enhance the hydrogen contents participating in the heat storage reaction are discussed. The heat charging and discharging performances at different positions in the hydride beds of MgH2–LaNi5 pair are characterized. Not only thermodynamic compatibility of MgH2 and LaNi5 but also kinetics as well as hydrogen and heat transfer in MgH2 beds considerably influence heat storage performance.

Investigation of the heat discharge from a solar-powered air heater with distinctive dual arc artificial roughness

In this study, an artificially roughened solar-based air heater (SBAH) is put through a series of experimental tests in an effort to improve its thermal properties employing distinctive dual arc artificial roughness. The artificially created roughness pattern disturbs the flow and augments the heat discharge behavior of SBAH surface. Under a predetermined sequence of flow Reynolds number (Re), the roughness with relative rib altitude (e/D) of 0.034 and variable relative distances of pitch (P/e) from 8 to 12 and relative distances of staggered pitch (P'/P) from 0.25 to 0.75 is experimentally examined. For e/D of 0.034, P/e of 10, and P'/P of 0.5, the determined Nusselt number (Nu) and friction factor (f) are derived as 2.27 and 3.10 times respectively as equated to a plane configured surface of SBAH. The experimental Nu and f have been correlated with the geometrical and flow variables considered, anticipating the thermal conduct of SBAH using distinctive dual arc roughness. The basis for this forecast is the experimental data that have been gathered.

Development of a Computational Fluid Dynamics Simulation Framework for Aerothermal Analyses of Electric Vehicle Battery Packs

Abstract The rise of electric vehicles has driven the extensive adoption of lithium-ion batteries (LIBs) due to their favorable attributes—compactness, low resistance, high power density, and minimal self-discharge. To enhance LIB reliability, an efficient battery thermal management system is imperative. This paper introduces a finite volume-based aerothermal analysis framework for a 32-cell high-energy density LIB pack. We also explore the effectiveness of various turbulence models in capturing local hotspots, discharge rates, and current levels across different geometries and inlet velocities. Our approach involves modeling the battery using Simcenter Battery Design Studio and importing it into Simcenter star-ccm+ for aerothermal simulations in which temperature distribution, discharge rates, current levels, and maximum temperature across are monitored for aligned, cross, and staggered configurations of the battery pack under varying inlet velocities. Our findings highlight the significant impact of boundary condition modeling on simulation stability. Also we observed that the standard k–ε model provides the most accurate predictions, with prediction accuracy within 3–10% of experimental data. Moreover, we identify substantial dependencies between heat generation and discharge current, as well as thermal gradients and inlet velocity. Finally, we conclude that the aligned cell arrangement offers the best thermal uniformity and cooling efficiency.

Application of graded phase change materials for solar energy inter-seasonal storage heating and thermal storage characteristics

Abstract In this paper, firstly, the heat transfer characteristics of the stepped phase change accumulator are studied, and the location of the solid-liquid phase interface is determined by the phase fraction in a fixed grid scheme, while the phase change heat transfer process is simulated using Fluent. Secondly, for the phase change heat transfer problem, the enthalpy-porosity method in the Solidification/Melting model is used to treat the solid-liquid mixed paste region of the phase interface as a porous media region, and the evaluation system is constructed in terms of heat storage and discharge efficiency, heat storage, and heat recovery efficiency. Then the mathematical model, boundary conditions and solution parameters of the stepped phase change heat accumulator are set, and the data analysis of the effect of the pool height-to-diameter ratio on the heat storage in the solar inter-seasonal storage heating system is carried out by using ANSYSCFD software. The results show that the heat storage of the system also shows an overall increasing trend with the increase of the pool height-to-diameter ratio, and the heat storage of the system increases faster when the height-to-diameter ratio increases from 0.2 to 1.0 in sequence, and the heat storage of the system increases less when the height-to-diameter ratio changes between 0.9 and 1.8, and basically tends to be stable. This study realizes the graded heat storage and graded heat use of solar energy, which is useful for the research of solar heat supply and heat storage.

Modelling and optimization of shallow underground thermal energy storage

Shallow geothermal reservoirs are excellent candidates for low-enthalpy energy storage, and can serve as heat batteries providing constant discharge of base heat, as well as rapid discharge of heat in periods of high demand. Recharging can be done by pumping down hot water, heated using excess heat from e.g. waste incinerators. In addition to having a very low carbon footprint, such systems also require limited surface infrastructure, and can easily be placed near or under the end-user, such as below residential buildings. The geological setting is typically complex, with horizons, faults, and intertwined patterns of natural fractures, and the nearwell region is often hydraulically fractured to enhance inter-well communication. Therefore, in order to fully utilize the potential of shallow geothermal heat storage, numerical simulations are imperative. In this work, we show how to practically model such systems, including generation of computational grids with a large number of wells and fractures, numerical discretizations with discrete fractures, and complex storage strategies with multiple wells working together under common group targets. We also discuss how adjoint-based methods can be used to tune model parameters (e.g. well injectivities, rock properties, and hydraulic fracture conductivities) so that the model fits observed data, and to find well controls (e.g. rates and temperatures) that optimize storage operations. The methodology is demonstrated using one artificial and two real underground thermal energy storage projects currently under development, and we highlight important challenges and our suggested solutions related to each of them. Thematic collection: This article is part of the Earth as a thermal battery: future directions in subsurface thermal energy storage systems collection available at: https://www.lyellcollection.org/topic/collections/thermal-energy

Latent heat thermal energy storage solution for CSPs: Integration of PCM heat exchangers

In the last few decades, alternate and renewable energy harvesting techniques, such as Concentrated Solar Power (CSP), have attracted attention as a unique source of electricity. However, the intermittent nature of solar energy results in discontinuous electricity generation. Thus, the integration of a Latent Heat based Thermal Energy Storage (LHTES) system will help in managing this issue. This numerical study explores the heat storage and discharge abilities of Phase Change Material (PCM) to design an efficient energy storage system. In this study, a 2D novel geometrical model is introduced to enhance the performance of PCM based heat exchanger module. Finite Volume Method (FVM) has been used to simulate the complex phase change problem via ANSYS Fluent solver. The double pipe heat exchanger with concentric cylinders is considered as the base case and multiple design modifications with augmented heat transfer areas have been provided. Comparison of different configurations by varying geometrical parameters with base case is carried out. The improvement in the rate of phase change is observed as the base case tube is replaced by semi-circular tubes in the system. The reduction in sensible heat storage is large during initial stages of charging, a reduction is observed as 46%, 43.5% and 48.9% respectively for all three cases. The time taken to achieve a maximum storage and discharge effectiveness of 82%, 85% respectively is less for novel configurations as compared to base case. It is observed that both novel configurations can be useful to store and release faster which can be used in meeting the energy demand on time.

Performance of different HDH desalination units powered by diesel engine generator waste heat

Diesel generators used for off-grid power generation and other applications waste a significant amount of input power as heat (about 65%), contributing to global warming. To mitigate this, waste heat recovery and utilization systems can be employed. The current study, focuses on utilizing waste heat from a 2.5 MW diesel generator for freshwater production through integrated humidification dehumidification (HDH) systems. Four different HDH system layouts are investigated, considering factors such as dehumidifier and humidifier effectiveness, temperature differentials, mass flowrate ratio, and ambient temperature. The aim is to analyze and optimize the system's pure water productivity, recovery ratio, specific entropy generation, and gained output ratio. The results show that the layout featuring an air heated – air heated cycle (AH-AH) performs the best, with the highest productivity and gained output ratio of 234.48 m3/day and 3.01, respectively. On the other hand, the water heated – water heated cycle (WH-WH) layout exhibits lower performance. The study demonstrates the potential to recover 46–70% of the waste heat, significantly improving the diesel engine's utilization factor from 36% to 68%. The proposed system also proves cost-effective, with freshwater production costing as low as 0.62 $/m3 when utilizing waste heat, compared to 4.11 $/m3 and 13.96 $/m3 when using steam or electric heating elements. Furthermore, the integrated system helps reduce the environmental impact by minimizing waste heat discharge into the environment and thus contributes to mitigating global warming.

Triple‐Dip La Niñas in 1998–2001 and 2020–2023: Impact of Mean State Changes

AbstractThis study compares the evolution of atmospheric and oceanic anomalies as well as predictions for the two most recent triple‐dip La Niña events in 1998–2001 and 2020–2023. Subsurface cooling in the equatorial Pacific was stronger and more persistent during 1998–2001. In contrast, surface easterly winds were stronger during 2020–2023 as was the east‐west sea surface temperature (SST) contrast along the equator. We argue that in the absence of appreciable equatorial Pacific heat discharge, persistent and strong surface trade winds and a strengthened mean zonal SST contrast across the tropical Pacific contributed to the development of the 2020–2023 triple‐dip La Niña. In terms of the subsurface layer heat budget, the growth and maintenance of unusually cold SSTs during the triple‐dip La Niña in 1998–2001 were mainly the result of ocean vertical entrainment and diffusion, as well as meridional advection, associated with enhanced equatorial upwelling; while for the triple‐dip La Niña in 2020–2023, zonal advection was the largest contributor. The two events were mostly well predicted by multi‐model averages at 1–8 months lead times. We hypothesize that mean state change with enhanced zonal SST contrast and trade winds over the last several decades altered the physical processes associated with the growth and maintenance of the most recent La Niña, affecting its predictability. Successful prediction in real‐time of the 2020–2023 event more than half a year in advance was surprising because there was little memory in oceanic heat content which is often considered a key predictor.

Experimental and numerical investigation of thermally induced convection along a high-temperature borehole heat exchanger

Thermally induced convection in the vicinity of borehole heat exchangers (BHE) in porous media affects the heat transfer behaviour between the BHE and the surrounding ground and thereby their performance for building climatization, heat extraction and heat storage. This study presents a combined experimental–numerical analysis of the qualitative and quantitative impacts of convection on heat transfer for a laboratory-scale BHE analogue over a wide temperature range. For this purpose, a grouted coaxial high-temperature BHE was installed within a fully saturated porous sand medium in a cylindrical container of 1.4 m3 volume under spatially extensive temperature monitoring. Four transient heat charging/discharging experiments were performed at different charging temperatures of 30, 50, 70, and 90 °C and analysed for the onset and magnitude of convection. After minimal calibration, a numerical model accurately reproduced the experimental data of all experiments and helped quantify the contribution of convection to the total heat transfer at each temperature level. For heat charging at 30 °C, the heat transfer was dominated by conduction. At higher temperatures, convection increased the total heat-transfer rate by up to 35% in the experimental setup. In contrast, for heat discharge, due to thermal stratification in the sand medium, convection reduced the heat transfer rate and heat recovery by up to −30% and −35%, respectively. Rayleigh numbers, buoyant flow velocities, and the centre of heat were derived from the monitoring and simulation data and consistently indicated the onset of convection for the experimental setup at a BHE operating temperature of 50 °C. The Rayleigh number was found to be closely correlated with the magnitude of the convective flow. Overall, the results suggest that the performance of BHEs in cooling applications may benefit from thermal convection, while the performance of BHEs for thermal energy storage may deteriorate markedly at high operating temperatures.

Numerical Study of a High-Temperature Latent Heat Thermal Energy Storage Device with AlSi12 Alloy

This paper explores the potential of thermal storage as an energy storage technology with cost advantages. The study uses numerical simulations to investigate the impact of adding porous material to the HTF side during solidification to improve the heat transfer effect of TES using AlSi12 alloy as the phase-change material. The research also examines the effects of adding porous dielectric materials and increasing air velocity on the discharge temperature, discharge power, and discharge time of high-temperature phase-change energy storage systems. The study found that the temperature difference of the PCM (increased), solidification time (reduced more than 85%), the outlet temperature of the air, and heat discharge power of the LHS did not vary significantly across different porous materials (copper foam, nickel foam, and silicon carbide foam) added to the HTF tube. These findings offer important information for the design of high-temperature phase-change energy storage devices and can guide future developments in this field.

Heat discharge performance of metal hydride thermal battery under different heat transfer conditions: Experimental findings

Thermal batteries utilizing metal hydride pairs are gaining tremendous research appeal for their applications in thermochemical energy storage. The pair consisting of a high-temperature metal hydride (HTMH: Mg-based hydride) and a low-temperature metal hydride (LTMH: AB2 type hydride) is attractive due to its relatively high energy storage density and medium energy storage efficiency. The energy storage efficiency can be significantly increased by improving the heat discharging performance of the thermal battery. In this study, we experimentally explore the heat releasing performance of an MgH2/(TiZr)(MnFeCr)2-based thermal battery. More specifically, the effects of LTMH bed heat transfer conditions on the heat discharging performance were briefly discussed. These heat transfer conditions include natural convection, forced convection, and resistive heating. The results showed that when operating the LTMH bed under active heat transfer conditions (forced convection or resistive heating), the thermochemical energy storage density varies between 1500 and 1820 kJ/kg-Mg with relatively high-temperature lift (heat upgrade) between 47 and 55 °C. On the other side, the thermal battery discharges heat at a relatively high specific power, ca. 100–225 W/kg-Mg, which can be a benefit for heat-to-work conversion applications using organic or steam Rankine cycles.

Progress on the Microwave-Assisted Recycling of Spent Lithium Battery Graphite

The robust development of electric vehicles has driven a surging decommission stream of lithium-ion batteries (LIBs) owing to their limited service life. The recycling of spent LIBs has become an urgent and essential task for the sustainable development of the LIB industry. However, the prevailing recycling methods focus only on recycling valuable metal, whilst the graphite anode materials are usually discarded or burned as fuels, leading to great waste of valuable carbon material. A facile strategy to obtain value-added products in an efficient manner is of great significance for the recycling of spent graphite. As graphite has excellent microwave absorption capability and electrical conductivity, microwave radiation on spent graphite can induce a Joule heat–discharge–plasma coupled effect, leading to a rapid heating process, especially when discharge occurs, exhibiting a thermal shock effect with the generation of a large number of high-energy electrons and active materials. This special feature facilitates microwave heating that is tailored for assisting the removal of impurities, structure repair, and graphite intercalation and exfoliation in an efficient manner. Therefore, different from the conventional graphite recycling route that is associated with energy/solution-intensive processes, this paper reviews the progress on microwave-assisted removal of impurities, repair of damaged graphite structure, and innovatively discusses the breakthroughs in microwave-assisted preparation of graphite intercalation compounds, expanded graphite, graphene and graphene-based materials, and porous graphene, with an aim to provide a scientific reference for the value-added resource utilization of spent graphite and preparation of new energy storage materials.

A Review of Oxygen Carrier Materials and Related Thermochemical Redox Processes for Concentrating Solar Thermal Applications.

Redox materials have been investigated for various thermochemical processing applications including solar fuel production (hydrogen, syngas), ammonia synthesis, thermochemical energy storage, and air separation/oxygen pumping, while involving concentrated solar energy as the high-temperature process heat source for solid-gas reactions. Accordingly, these materials can be processed in two-step redox cycles for thermochemical fuel production from H2O and CO2 splitting. In such cycles, the metal oxide is first thermally reduced when heated under concentrated solar energy. Then, the reduced material is re-oxidized with either H2O or CO2 to produce H2 or CO. The mixture forms syngas that can be used for the synthesis of various hydrocarbon fuels. An alternative process involves redox systems of metal oxides/nitrides for ammonia synthesis from N2 and H2O based on chemical looping cycles. A metal nitride reacts with steam to form ammonia and the corresponding metal oxide. The latter is then recycled in a nitridation reaction with N2 and a reducer. In another process, redox systems can be processed in reversible endothermal/exothermal reactions for solar thermochemical energy storage at high temperature. The reduction corresponds to the heat charge while the reverse oxidation with air leads to the heat discharge for supplying process heat to a downstream process. Similar reversible redox reactions can finally be used for oxygen separation from air, which results in separate flows of O2 and N2 that can be both valorized, or thermochemical oxygen pumping to absorb residual oxygen. This review deals with the different redox materials involving stoichiometric or non-stoichiometric materials applied to solar fuel production (H2, syngas, ammonia), thermochemical energy storage, and thermochemical air separation or gas purification. The most relevant chemical looping reactions and the best performing materials acting as the oxygen carriers are identified and described, as well as the chemical reactors suitable for solar energy absorption, conversion, and storage.

Experimental study on design optimization of the core catcher for the CEFR

ABSTRACT In severe accidents, sodium-cooled fast reactors (SFRs) are more concerned with core disruptive accidents (CDAs), and in-vessel retention (IVR) is an important mitigation measure to ensure the integrity of the reactor vessel. The distribution and accumulation uniformity of the melt in the lower chamber seriously affects the residual heat discharge capability. The installation of a core catcher is an effective mitigation method, and its structure and arrangement play a key role in mitigating severe accidents. In this study, the experimental facility is designed based on the core catcher of the China Experimental Fast Reactor (CEFR). An experimental platform is established to simulate the falling and relocation of melts in the core catcher under the condition of CDAs. At the same time, a quantitative evaluation index is established to analyze the influence of the number of chimneys, the inclination angle of the chimney canopy, the central chimney height, and the spacing of chimneys on relocation of melts in the core catcher. Finally, some suggestions for correlation optimization design are given.