Synthesis optimisation of copper-based layered perovskites as thermal energy storage materials

Solid-solid phase change materials (ss-PCMs) are promising materials for thermal energy storage applications because they do not require shape stabilisation or encapsulation. In addition, depending on the ss-PCM used, they can reduce corrosion issues and allow faster charging and discharging. Organometallic ss-PCM, particularly layered hybrid organic-inorganic compounds, have been investigated in this work due to the scientific interest in their potential use as phase change materials to store energy via polymorphic transitions. Here we have assessed the synthesis of (C12H28N)2CuCl4, a potential material for thermal energy storage. The transition enthalpy and specific heat are the key values to maximise. Two different synthesis procedures were followed: reflux and recrystallisation, and direct synthesis. Three different solvents were also used: methanol, ethanol and isopropanol. In order to find out which processes and solvent media were most promising, the synthesis yield, crystal and molecular structure, and thermal parameters such as transition enthalpy and specific heat were evaluated. Direct synthesis processes produced the most promising material for thermal energy storage due to higher yield and better enthalpy ratio

The relevance of thermochemical energy storage in the last two decades: The analysis of research evolution

The research field on thermochemical energy storage (TCS) has shown consistent growth over the last decade. This study analysed over 1196 scientific publications in indexed journals and books from the last decades. What can we learn from analysing the evolution of research? There is no other study that has used bibliometrics to perform a detailed analysis of the TCS field, which has only been assessed from the perspective of the whole thermal energy storage field to date. The trends obtained in this study provide an important perspective of the field, indicating the strengths and weaknesses of the thermochemical materials and systems applied to energy storage. The main publication trend shows an exceptional increase in TCS research and in both defined research sub-areas (sorption and chemical reaction heat storage). The sub-category chemical reaction heat storage has fewer publications compared to sorption heat storage, indicating that it is a less explored field. In general, the evolution of the keywords in publications reflects technology maturity since the most recent terms are associated more with final use applications. Remarkably, there has been a change from a total dependence on funding for scientific output to a scenario in which a significant number of publications mention no specific funding, but this trend has changed in recent years

Novel shape-stabilized phase change material with cascade character: synthesis, performance and shaping evaluation

Thermal Energy Storage (TES) materials, such as Phase Change Materials (PCMs) are proven to enhance the energy efficiency in many fields, such as automotive and building sectors, which correspond to the most energy intensive ones. Shape-stabilized PCM and cascade PCM are procedures to overcome the most important barriers when PCMs are applied since PCMs need to be encapsulated for their technical use: the leakage of the liquid phase, corrosion, low heat transfer and narrow temperature of application. In the present study, a novel shape stabilized PCM with cascade performance (cascade shape stabilized phase change material, CSS-PCM) is synthesized via dissolution, which allows up to 60 wt.% of a paraffin-PCM in the final composition. The novel CSS-PCM is based on a biopolymer, the polycaprolactone (PCL), a low melting temperature polyester as polymeric matrix and RT27 and Micronal DS 5040 acting as PCM. To evaluate the performance of the new TES materials developed, several techniques have been used: Differential Scanning Calorimetry (DSC), and Fourier-Transformed Infrared (FT-IR) spectroscopy were used to evaluate the thermophysical properties and the chemical properties of the different formulations. The CSS-PCM show an increment of storage capacity by increasing the PCM content, and the thermal reliability was also tested: some of the CSS-PCM formulations were stable for up to 500 thermal cycles. Finally, as a potential application of the new polymeric-based PCM 3D, a printing attempt was performed in order to analyze the viability of the formulations to be used as 3D printing material as a first proof of concept

Manufacturing of nano-enhanced shape stabilized phase change materials with montmorillonite by Banbury oval rotor mixer for buildings applications

The use of adequate thermal energy storage (TES) systems has shown the potential to increase energy efficiency in many fields, such as the building sector. Shape-stabilized phase change materials (SS-PCMs) have attracted attention to address one of the key barriers of phase change materials (PCMs), the leakage during the liquid state, that nowadays limits its applicability. However, SS-PCMs still have drawbacks to overcome, such as poor fire reaction and thermal stability. In the present study, polymeric SS-PCMs are nano-enhanced with layered silicates to overcome these drawbacks. The new shape-stabilized nano-enhanced phase change material (SS-NEPCM) is based on ethylene propylene diene monomer (EPDM) as a polymeric matrix, palmitic acid (PA) as PCM and montmorillonite (MMT) as the layered silicate. An innovative method based on a Banbury mixer was used to prepare it, which is an industrially scalable fabrication method. To evaluate the effect of each component, eight different formulations were prepared: pure EPDM, EPDM with MMT additions (1 wt%, 3 wt% and 5 wt%), EPDM with PA additions (5 wt% and 10 wt%) and EPDM with MMT (3 wt%) and PA additions (5 wt% and 10 wt%). The composite materials obtained were not degraded by processing as FT-IR results show. The results obtained by X-ray diffraction showed that an ordered intercalated morphology is formed between EPDM chains and MMT. Thermogravimetric experimental results revealed an increase in the thermal stability of SS-NEPCM as a result of the barrier effect provided by MMT. Moreover, SS-NEPCM fire resistance was improved with a great reduction or avoidance of the dripping phenomenon

Assessment of Solid Wastes and By-Products as Solid Particle Materials for Concentrated Solar Power Plants

The revalorization of solid wastes and by-products to be applied as solid particles in concentrated solar power (CSP) leads to cost savings and progresses toward more sustainable technology. Herein, the physicochemical, morphological, thermal, and solar absorption properties are evaluated for electric arc furnace dust, black slag from the steel industry, and Gossan waste from the Rio Tinto mining industry. The principal objectives of this work are (i) to carry out a thermal aging at 900 °C at different times, (ii) to assess the solid's stability throughout the evaluation of physicochemical, morphological, thermal, and optical properties of the material as received, after 300 and 500 h of thermal aging, and (iii) to determine the most appropriate candidate as a thermal energy storage medium and heat transfer fluid for the CSP concept with solid particles. The results show that electric arc furnace black slag is the most suitable candidate from the three solids studied, as it is the one that optimizes the combination of absorptance, thermal conductivity, and chemical stability after thermal aging

Research evolution of limestone calcined clay cement (LC3), a promising low-carbon binder – A comprehensive overview

Limestone calcined clay cement (LC3) is a recently developed binder with huge potential to reduce the clinker factor in cement and the environmental impact. This study aimed to evaluate the evolution of the research on LC3 by conducting a bibliometric analysis, evaluating key metrics such as publications, authorships, sources, or countries, to provide greater knowledge and a strategic vision of this technology. This work provides an important perspective of the field and elucidates the research trends and path that the LC3 technology followed from its beginning to date. The analysis reveals a noticeable increase in technology readiness and researchers' interest, as indicated by a significant rise in publications' number over time. Also, the authorship metrics reveal an important cooperation between communities in the development of this technology. The research on LC3 is essential since the technology is a viable and reliable approach to decreasing the cement industry's carbon footprint

Reused and recycled. Archeometallurgical study of historical nails found in Guam, Mariana Islands, Western Pacific

This article presents the results of the archaeometallurgical analyses (chemical, compositional, and mechanical) conducted on historic iron nails from the Marianas archipelago, in the western Pacific. The nails were recovered at the archaeological excavations of San Dionisio’s church and cemetery (Humåtak, Guam). They all came from abroad and were incorporated by the native communities through exchange, trade, or through the reuse of materials found in shipwrecks, although it is not possible at the moment to locate their exact origin. However, we know that all the analyzed samples had different metallographic and mechanical characteristics. This is the first study of these characteristics on Micronesia.We would like to thank Carmen Quintanilla and Melanie Dueñas, from the Micronesian Area Research Centre at the University of Guam, for helping us with information about contemporary blacksmithing. We would also like to thank SHIPO-State Historical Preservation Office in Guam and Joe Quinata from GPT-Guam preservation Trust for their help and support to obtain permission for archaeological samples. This work has been partly supported by the Spanish Ministry of Economy and Competitiveness under Grant PID2019-105431GB-I00, and by the ABERIGUA grant (sponsored by the Palarq Foundation and the Spanish Ministry of Culture and Sports). A.I. Fernández would like to thank the Catalan Government for the quality accreditation given to her research group (DIOPMA 2017 SGR 0118). DIOPMA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia

Case study of pipeline failure analysis from two automated vacuum collection system

Conventional municipal waste management systems based on collecting and storing waste for future management are cost-effective and flexible. These systems present significant problems such as odours, plagues and hygiene problems caused by their storage and greenhouse gas emissions from garbage trucks used for the transport of waste. The Automated Waste Collection System (AWCS) and Automated Vacuum Waste Collection (AVWC) systems, in which waste is transported directly underground to the processing plants, are efficient collection systems and respectful of the environment as alternatives to traditional systems. The pneumatic system reduces the value of the per capita generation of general waste. The present study explains the origin of pipe failure in two different AWCS factories, as well as the identification of the failure phenomena. To carry out the study, a classification of 90 failure cases by primary cause was performed, followed by recommendations to avoid these failures in the future. Moreover, a computational fluid dynamics (CFD) simulation was performed in order to help in the failure determination and the key recommendations to avoid the most common and frequent failures

New shape-stabilized phase change materials obtained by single-screw extruder

Shape-stabilized phase change materials (SS-PCM) are promising materials given their potential to control leakage of liquid PCM. However, SS-PCM still has low thermal conductivity and high flammability, which are important properties for several applications, such as the thermal indoor comfort in buildings. In this study, two new polymeric SS-PCM were developed and their properties were optimized by the use of different additives. Both high-density polyethylene (HDPE) and polyoxymethylene (POM) work as matrix materials and MPCM 28 from Microtek acts as PCM. Besides, the graphite was used as an additive material to increase the thermal conductivity, and the magnesium hydroxide to minimize flammability of the composite. Both inorganic fillers also help in the PCM dispersion within the matrix. To evaluate the effect of each component, seven formulations were manufactured by a single screw extruder and a set of characterization (Differential scanning calorimetry, Thermogravimetric analyses, for thermophysical evaluation, and dynamical mechanical analyses, for thermomechanical evaluation over 1000 thermal cycles was performed. The main outputs of the investigation are the proposed formulations that have a good fire reaction performance, whereas their thermal and chemical stability are guaranteed up to 1000 cycles. The HDPE samples present around 12 kJ/kg melting enthalpy when 10 wt% microencapsulated PCM is included in the formulation. In addition, the POM samples present around 7.5 kJ/kg when 10 wt% microencapsulated PCM is included in the formulation. For all formulations, the melting enthalpy obtained is around 27.5°C, in concordance with the reported by the manufacturer

Viscoelastic characterization of seven laminated glass interlayer materials from static tests

The mechanical behaviour of laminated glass is strongly affected by the polymeric interlayer placed between glass layers. In general, this interlayer is a viscoelastic material, and therefore it may experience creep and stress relaxation when subjected for an extended period to a constant stress or strain respectively. In this study, seven different commercial interlayer materials (EVALAM, EVASAFE, PVB BG-R20, Saflex DG-41, PVB ES, SentryGlas, and TPU) were evaluated with relaxation tests at different temperatures, in order to build the relaxation master curves through the time-temperature superposition principle. A generalized Maxwell model was chosen to describe the viscoelastic behaviour of the tested materials. This paper includes the coefficients of the Prony series that fit better the experimental results. This paper has two main goals. First, to present the Prony coefficients (ei and si), which can then be used to create numerical models that take into consideration the time and temperature-dependant behaviour of the interlayer. Second, to provide the two components of the complex modulus (E*(x)) of each material, the storage modulus (E'(x)) and the loss modulus (E''(x)), which can be obtained from the relaxation modulus (E(t)) by using analytical interconversions