Heat transfer simulation in encapsulated phase change materials for energy storage applicationWang, Han; Jadidi, Mohammad; Mahmoudi, Yasser
doi: 10.1088/1757-899x/1331/1/012002pmid: N/A
In the pursuit of sustainable energy systems, the complexity of technological integration is crucial for overcoming future challenges. Encapsulated Phase Change Materials (EPCM) have emerged as prominent players in this field due to their exceptional heat storage capabilities, offering vital and efficient energy management solutions for diverse eco-friendly applications. Despite their appealing characteristics, the large-scale integration of EPCM faces hurdles, particularly concerning the maintenance of structural integrity amid phase transitions characterized by uneven thermal distribution and stress accumulation due to volume changes. These challenges can lead to structural damage, thereby impacting system efficiency, environmental safety, and hindering public acceptance and utilization of EPCM technologies [1][2]. Recent studies have explored the behaviour of Encapsulated Phase Change Materials (EPCM) through simulations. However, many of these studies still rely on simplified unrealistic assumptions, such as maintaining constant volume during phase changes, thereby neglecting the complex stress scenarios encountered in practical applications [3]. This study establishes a comprehensive model to simulate the conjugate heat transfer process in EPCM, encapsulating it within a solid sphere and exposing it to a turbulent environment. The heat transfer coefficients between different interfaces throughout the heat transfer process were investigated using computational fluid dynamics (CFD) simulations. In addition, the analysis focused on the uneven temperature distribution, which was verified to be mainly caused by changes in the contact medium within the encapsulation material and boundary layer separation on the outer surface.
Experimental investigation of SrBr2·6H2O-based composite thermochemical material for low-temperature thermochemical heat storageMa, Hongkun; Ji, Mingxi; Chen, Jie; Ahmad, Abdalqader; Meng, Dongyu; Ding, Yulong
doi: 10.1088/1757-899x/1331/1/012003pmid: N/A
Thermochemical energy storage (TCS) represents one of the three thermal energy storage (TES) technologies, alongside sensible heat and latent heat storage. TCS has the highest energy density among these TES technologies, with nearly zero heat loss during storage. However, TCS remains relatively underdeveloped, with an overall low Technology Readiness Level of 1-3. The main challenges include limited cycle lifespan and low controllability of the charging/discharging kinetics. We report a study on SrBr2·6H2O-based thermochemical materials, particularly their thermal cyclability and kinetics of dehydration (charging) and hydration (discharging) processes of the materials. The results show that the dehydration could be completed within 100 min when the temperature is over 70 °C. The hydration process was found to work well at 18-50% RH, indicating that the SrBr2·6H2O pair has a fairly wide range of operating conditions. The hydration of the SrBr2·6H2O pair can be finished within 2 hours. Additionally, the performance of SrBr2·6H2O-based composite thermochemical materials was studied in a packed bed reactor and the results show that the outlet temperature could achieve 50 °C, with the highest temperature lift of ~35 °C. This suggests that the SrBr2·6H2O-based composite material could find applications in hot water supply and space heating.
Prefacedoi: 10.1088/1757-899x/1331/1/011001pmid: N/A
UKES2024 – the 2024 energy storage conference and its outcomes. (a foreword to the special issue of papers from UKES2024)Prof. Seamus Garvey, University of Nottingham.One thing is certain about the inevitable – it will eventually happen! UKES2024, the 2024 instance of UK Energy storage conference, took place at the University of Nottingham from April 10 – 12, 2024. Like every conference, UKES2024 had its own quite unique flavour and its own very singular core message. That core message can probably be summarised as: Energy Storage is many-faceted, it’s real and it is going to be very big - inevitably!UKES2024 continued a tradition established by previous instances of the UKES conference by bringing together a wide range of expertise and backgrounds to discuss research right at the cutting edge. Previous UKES conferences have not assembled a proceedings, and the invitation to authors to submit a full journal paper was therefore something of an experiment. This resulting volume is small but nonetheless filled with gems and I commend it to the reader. With over 100 presentations in the conference, this volume does not cover the full spread of topics that were touched-upon in UKES2024. For that reason, I offer the remaining paragraphs here as something of an overview of UKES2024 and I will let the journal papers included herein speak for themselves.The executive committee that made UKES2024 possible comprised:Prof. Seamus Garvey, Conference Chair. (University of Nottingham)Ms. Annabel Brown (Energy Engineer at ARUP)Prof. Solomon Brown (University of Sheffield)Prof. Christos Markides (Imperial College)Prof. Daniel Friedrich (University of Edinburgh)Prof. Katriona Edlmann (University of Edinburgh)
Orchestrating Propagation of Heat and Reaction Fronts in a Packed Bed of SrFeO3-δ for Energy Storage ApplicationsFarhan Bin Abu Kasim, Abu; Marek, Ewa J.
doi: 10.1088/1757-899x/1331/1/012007pmid: N/A
Non-stoichiometric oxides can undergo reversible redox reactions without crystallographic phase transformations – a unique property that remains underexplored in energy storage applications. The reduction of non-stoichiometric oxides, like SrFeO3-δ, is an energy sink, whilst its oxidation leads to energy release. Together, these reactions can be used for energy charging and discharging in the storage cycles. Here, we look into redox reactions of SrFeO3-δ, triggered by manipulating the oxygen partial pressure (pO2). The experimental work was carried out at 600°C, with SrFeO3-δ in a packed bed, exposed to mixtures of N2 and air, with a higher value pO2 in the discharging step (oxidation) and a lower pO2 in the charging step (reduction). The extent of reaction in the bed was associated with heat and reaction fronts, the first describing the energy distribution, the latter the uptake or release of oxygen in the reactions with particles of SrFeO3-δ. Propagation of both fronts was deduced from spatial-temporal changes in temperatures of the SrFeO3-δ bed, measured with an array of thermocouples, and with the content of oxygen in the off-gas, measured with a paramagnetic analyser. Our experiments demonstrate that large shifts in pO2 cause the reaction front to lead the heat front, whilst smaller variations in pO2 result in the reversed order and even overlapping of the fronts. These results, hence, exemplify the versatility of operation and usage of non-stoichiometric oxides for energy storage.
Peer Review Statementdoi: 10.1088/1757-899x/1331/1/011002pmid: N/A
All papers published in this volume have been reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.• Type of peer review: Double Anonymous• Conference submission management system: Morressier• Number of submissions received: 10• Number of submissions sent for review: 10• Number of submissions accepted: 8• Acceptance Rate (Submissions Accepted / Submissions Received × 100): 80• Average number of reviews per paper: 2.5• Total number of reviewers involved: 14• Contact person for queries:Name: Seamus GarveyEmail: [email protected]: University of Nottingham
Assessing the regional demand for geological hydrogen storage: building a strategic case for investment in the east coast clusterEdlmann, Katriona; Todd, James; Hoffman, Colleen; Kemshell, Adam; Williams, Henry; Garvey, Christian; Noone, Maria; Seakins, Joe; Armitage, Tim
doi: 10.1088/1757-899x/1331/1/012008pmid: N/A
Hydrogen will play a central role in the UK’s journey towards achieving net-zero emissions by 2050. However, it faces significant barriers to its widespread adoption such as the current lack of hydrogen infrastructure, including in storage networks. Addressing these barriers will require concerted efforts from policymakers, industry stakeholders, and researchers to overcome technological, economic, and regulatory hurdles and unlock hydrogen’s full potential.This study presents a cluster-specific assessment of hydrogen storage demand and capacity in the East Coast Cluster (ECC). Through an analysis of likely hydrogen demand and storage requirements, and an assessment of potential capacity offered by salt cavern storage, a comprehensive evidence base to support the case for change associated with long-duration energy storage (LDES) was established. The ECC is found to have an estimated hydrogen storage capacity of 22-48 TWh, dependent on the input parameters and risk tolerance applied. While the storage capacity is likely to meet 2030-2035 storage targets, longer term 2050 storage targets will exceed the available capacity. Furthermore, while this study presents a significant volume of storage capacity in the region, the range shows represent an approximately 70-90% reduction on published estimates.In demonstrating the case for the ECC, where the situation appears to be most optimistic, the findings should be viewed in the context of the even greater challenge of ensuring a national LDES capacity, delivered at the scale and pace required to meet demand. Therefore, minimum regret interventions, such as strategic planning and further development on demonstrator storage projects, are recommended with urgency, otherwise the required storage capacity will not be delivered on time.
Simplified Thermodynamic Analysis of Adiabatic Compressed Air Energy Storage Integrated with High-Temperature Thermal StoragePrasad Jenne, Sunku; Li, Chenghao; Zhang, Xuecen; Navarro, Helena; Wang, Jihong; He, Wei; Spencer, Joe
doi: 10.1088/1757-899x/1331/1/012006pmid: N/A
Compressed air energy storage (CAES) presents promising potential as a low-cost, long-duration, and large-scale energy storage solution. However, the lower specific work output and less flexibility are the limitations of the current state of the art. An adiabatic compressed air energy storage (ACAES) system integrated with high-temperature thermal energy storage (HTES), known as Hi-CAES, is investigated to address these challenges. This integration aims to enhance specific work output and operational flexibility. The proposed Hi-CAES system uses excess renewable energy to charge the compressor and the HTES through joule heating elements. The system achieves higher specific work output by increasing the turbine inlet temperature. A simplified thermodynamic analysis evaluates the round-trip efficiency (RTE) and specific work output of both ACAES and Hi-CAES systems. The results indicate that the RTE of the ACAES system with a 2-stage compression/expansion reaches a maximum of 80% within the cavern operating pressure range of 143-170 bar, declining thereafter. While the Hi-CAES system’s RTE is lower than the ACAES, the Hi-CAES demonstrates a specific work output 1.9 times higher than the ACAES. Furthermore, in the Hi-CAES system, the external heat supplied is converted into work with a significantly higher efficiency of up to 57%, which surpasses the efficiency of conventional heat-to-work conversion devices.
An air liquefaction system integrated with organic Rankine cycle for performance enhancement and energy savingHuang, Yixuan; Ahmad, Abdalqader; Zhang, Tongtong; Song, Jian; Ding, Yulong
doi: 10.1088/1757-899x/1331/1/012001pmid: N/A
Liquid air energy storage (LAES) is one of the most promising large-scale energy storage technologies that are capable of providing different energy services to ensure the stability and flexibility of the grid with a high renewable penetration. Examples of such services include peak shaving, renewable firming and transmission constraint management. The LAES technology has several advantages relative to other energy storage technologies due to its high energy density, multi-functionalities, no geological constraints, environmental friendliness and scalability. However, the round-trip efficiency (RTE) of a standalone LAES system is around 50-60%, mainly due to the energy-intensive air liquefaction process (i.e., charging process), which, on average, consumes 0.22–0.7 kWh electricity to produce 1 kg liquid air. To reduce this electricity consumption, recycling high-grade cold energy from the liquid air regasification (power recovery) process has been utilized. However, this is not available in some cases, such as at the system start-up stage or when liquid air is used for black start applications. Additionally, partial loss of cold energy during storage, coupled with insufficient utilisation of compression heat, further reduces the RTE. In these cases, a back-up of liquid air produced in an energy-efficient way is need and to address this, we propose an air liquefaction system integrated with an organic Rankine cycle (ORC). This integrated system aims for utilisation of the compression heat by driving an ORC unit. Thermodynamic analyses indicate that the integrated systems allow the operation of air liquefaction unit at a much higher pressure up to 250 bar, leading to increased liquid air yield and reduced energy consumption by 25.36%.
State of charge estimation approaches for domestic thermal storage using phase change materialZhang, Manyu; Wilson, James; Roger, Timothy J.; Barthorpe, Robert J.
doi: 10.1088/1757-899x/1331/1/012005pmid: N/A
This paper discusses the development and implementation of State of Charge (SoC) estimation methods for a domestic-scale Phase Change Materials (PCM) system, aimed at enhancing energy storage system management and efficiency. Addressing challenges such as the complexity of physical processes and the need for real-time algorithm operation, the study integrates physics-based insights with statistical analysis of training data to accurately predict the thermal energy stored. The estimation process relies on a historical dataset of temperature measurements collected from multiple points within the PCM system, providing a comprehensive understanding of thermal behaviour over time. The research involves an experimental program for data collection, starting with linear regression analysis of temperature data to assess thermal performance and standing loss, followed by piecewise linear approximation to characterise the transition between sensible and latent heat processes. Advanced regression techniques, specifically Gaussian Process (GP) models trained on diverse operational data, demonstrate strong predictive capability in forecasting system performance. By leveraging historical temperature profiles, this approach significantly enhances SoC estimation accuracy for PCM systems and optimises charging and discharging cycles in domestic settings. The findings contribute valuable insights and methodologies to the field of thermal energy storage, supporting the development of more efficient and intelligent energy management strategies.
A Titanium Manganese Redox Flow Battery-Electrolyser with Lead-Dioxide Positive ElectrodeBarton, J P; Brenton, M; Ashton, E.; Wilson, J; Strickland, D
doi: 10.1088/1757-899x/1331/1/012004pmid: N/A
Redox flow battery electrolysers can act as both batteries for long-duration energy storage and as electrolysers for the production of hydrogen and oxygen. The hydrogen is an additional energy storage vector whose production can make use of renewable electricity generation that would otherwise be curtailed. This paper presents a titanium-manganese redox flow battery electrolyser. Charging and electrolysis functions use one cell stack with lead dioxide positive plates to withstand the high voltages and highly acidic conditions. Discharging takes place in a second cell stack using electrodes made of low-cost carbon materials. The charging cell exhibits good Faradic efficiency when fully charged and operating as an electrolyser (near 100%) but only poor efficiency when cycling as a redox flow battery (17%). This technology could be combined with a lead-acid battery-electrolyser so that the energy capacity and duration of electricity storage can be expanded independently of power rating. The combined device can be fully discharged, fully charged, over-charged and indefinitely cycled without oxidation imbalance. Five cycles have been demonstrated in the laboratory, each consisting of 17 hours charging and 5 hours discharging. The raw materials are cheaper and have lower environmental impact than the market leading all-vanadium redox flow batteries.