Thermochemical Materials Research Articles

Implementation of an Integrated Problem Based Learning Model in Generic Science Skills in Thermochemical Material

This research aims to determine the effect of Prior Knowledge Evaluation, Student Worksheets on student learning outcomes using the Problem Based Learning Model Integrated Generic Science Skills on Thermochemical Material. This research was carried out at SMAN 2 Percut Sei Tuan in the 2022/2023 academic year, the research was designed using a dual paradigm with two independent variables, namely Prior Knowledge Evaluation and Student Worksheets and one dependent variable, namely Evaluation of Learning Outcomes. The population in this study was all class XI at SMAN 2 Percut Sei Tuan. The sample used class XI B as an experimental class taught with Prior Knowledge Evaluation, Student Worksheets and Evaluation of Learning Outcomes tools using the Generic Science Skills Integrated PBL Learning Model. Sampling was using purposive sampling technique. The instruments used in this research consisted of 25 Prior Knowledge Evaluation questions, 15 Student Worksheets questions and 28 Evaluation of Learning Outcomes in multiple choice form which had been developed by previous researchers. The results of this study that thereare significant influence between Prior Knowledge Evaluation and Student Worksheets on learning outcomes. There are differences in learning outcomes between students who have low Prior Knowledge Evaluation and high Prior Knowledge Evaluation.

Adsorption‐Based Thermal Energy Storage Using Zeolites for Mobile Heat Transfer

ABSTRACTThe utilization of the water–zeolite pair as an adsorbate–adsorbent system has garnered significant attention in the realm of thermochemical energy storage, offering great potential for various applications. Despite promising results in laboratory settings, widespread implementation of this technology has yet to be realized. Recent advancements in mobile thermal energy storage (m‐TES) employing thermochemical materials have opened new avenues for enhancing the practicality and cost‐effectiveness of solar thermal energy harnessing and waste heat recovery. This experimental study investigates the feasibility of storing thermal energy in zeolites, charged externally to the heat recovery reactor, and discusses the potential applications of externally charged zeolites for m‐TES over short distances, shedding light on their practicality and significance in advancing the field of mobile thermal energy storage. Our findings reveal that zeolites charged at 200°C and subsequently stored outside the discharging unit exhibit an impressive energy storage density (ESD) exceeding 110 kWhth/m3 under conditions of 0.45 m/s air velocity and 60% relative humidity during zeolite discharging. These ESD values are comparable to previously reported figures in the literature. Moreover, ESD values of 30.6 kWhth/m3 were achieved by charging zeolite beads contained within packed transportable tubes constructed from stainless‐steel mesh.

Tutton salt (NH4)2Zn(SO4)2(H2O)6: thermostructural, spectroscopic, Hirshfeld surface, and DFT investigations

ContextAmmonium Tutton salts have been widely studied in recent years due to their thermostructural properties, which make them promising compounds for application in thermochemical energy storage devices. In this work, a detailed experimental study of the Tutton salt with the formula (NH4)2Zn(SO4)2(H2O)6 is carried out. Its structural, vibrational, and thermal properties are analyzed and discussed. Powder X-ray diffraction (PXRD) studies confirm that the compound crystallizes in a structure of a Tutton salt, with monoclinic symmetry and P21/a space group. The Hirshfeld surface analysis results indicate that the main contacts stabilizing the material crystal lattice are H···O/O···H, H···H, and O···O. In addition, a typical behavior of an insulating material is confirmed based on the electronic bandgap calculated from the band structure and experimental absorption coefficient. The Raman and infrared spectra calculated using DFT are in a good agreement with the respective experimental spectroscopic results. Thermal analysis in the range from 300 to 773 K reveals one exothermic and several endothermic events that are investigated using PXRD measurements as a function of temperature. With increasing temperature, two new structural phases are identified, one of which is resolved using the Le Bail method. Our findings suggest that the salt (NH4)2Zn(SO4)2(H2O)6 is a promising thermochemical material suitable for the development of heat storage systems, due to its low dehydration temperature (≈ 330 K), high enthalpy of dehydration (122.43 kJ/mol of H2O), and hydration after 24 h.MethodsComputational studies using Hirshfeld surfaces and void analysis are conducted to identify and quantify the intermolecular contacts occurring in the crystal structure. Furthermore, geometry optimization calculations are performed based on density functional theory (DFT) using the PBE functional and norm-conserving pseudopotentials implemented in the Cambridge Serial Total Energy Package (CASTEP). The primitive unit cell optimization was conducted using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. The electronic properties of band structure and density of states, and vibrational modes of the optimized crystal lattice are calculated and analyzed.Graphical abstract

Open-cycle thermochemical energy storage for building space heating: Practical system configurations and effective energy density

Salt-hydrate thermochemical materials (TCM) are promising candidates for energy storage systems for building space heating due to their high theoretical energy density and the need for low regeneration temperature. However, water vapor is required to drive the hydration process of the TCM reactor, which poses a challenge during winter when water vapor is typically scarce. Using indoor air directly lowers the building's humidity to an unconformable level in practice, while the cold outdoor air contains limited moisture. Here we consider different integration strategies for open-cycle TCM reactors in buildings and develop a model to simulate their thermal performance across diverse buildings and climates, specifically for building space heating. The potential energy densities and the levelized cost of storage of the TCM reactor are evaluated in practical scenarios to demonstrate the load-shifting potential of TCM systems for heating applications. We use a strontium chloride (SrCl2)-based composite as the baseline and explore the impact of various reactor and material changes to the energy density and levelized cost of storage.

Guided Discovery-based thermochemistry modules to enhance critical thinking ability and process science skills: development and experimental results

The purpose of this study was to determine the results of testing the development of chemical modules on thermochemical materials. The method used in this study is a mixed method, namely qualitative and quantitative methods. Twelve assertions about the module, including its substance, language, presentation, and graphics, were included in a questionnaire that was used to collect the data. In order to improve the module, respondents were given the opportunity to offer suggestions at the conclusion of the questionnaire. The research's trial portion was conducted in two stages, a minor test and a major test. Chemistry instructors and pupils from three state senior high schools served as the study's subjects. While 30 students and 5 teachers were present for the major trial, only 15 students and 3 teachers were present for the minor trial. The results of the quantitative analysis obtained an average minor test result of 73.91% in the good enough category for teachers and 74.72% for students in the good enough category. Major test results obtained an average of 82.5% in the very good category for teachers and 80.13% for students in the very good category. The qualitative method is based on the suggestions given by the teacher and students and obtained from the questionnaire. There were several suggestions for revisions obtained during these two stages, namely the need to add the amount of information about chemistry, add answers to questions in the module, add pictures or illustrations, correct some typing errors, and slightly enlarge the column of student answers in the module.

Characterizing Changes in a Salt Hydrate Bed Using Micro X-Ray Computed Tomography

Thermochemical storage using salt hydrates presents a promising energy storage method. Ensuring the long-term effectiveness of the system is critical, demanding both chemical and mechanical stability of material for repetitive cycling. Challenges arise from agglomeration and volume variations during discharging and charging, impacting the cyclability of thermochemical materials (TCM). For practical usage, the material is often used in a packed bed containing millimetre-sized grains. A micro-level analysis of changes in a packed bed system, along with a deeper understanding involving quantifying bed characteristics, is crucial. In this study, micro X-ray computed tomography (XCT) is used to compare changes in the packed bed before and after cycling the material. Findings indicate a significant decrease in pore size distribution in the bed after 10 cycles and a decrease in porosity from 41.34 to 19.91% accompanied by an increase in grain size, reducing void space. A comparison of effective thermal conductivity between the uncycled and cycled reactor indicates an increase after cycling. Additionally, the effective thermal conductivity is lower in the axial direction compared to the radial. XCT data from uncycled and cycled experiments are further used to observe percolation paths inside the bed. Furthermore, at a system scale fluid flow profile comparison is presented for uncycled and cycled packed beds. It has been observed that the permeability decreased and the pressure drop increased from 0.31 to 4.88 Pa after cycling.

In situ thermal conductivity measurement revealing kinetics of thermochemical reactions

Utilizing thermochemical reactions for thermal energy storage and solar fuel production has been an emerging research topic. Thermal transport properties of the materials are an important parameter that can determine the kinetics and efficiency of thermochemical reactions. With the increasing number of new thermochemical materials (TCMs); however, there is a lack of reliable techniques to monitor the thermal transport property of the materials and their changes as a function of reactions in real time. In this work, we report the in situ monitoring of thermochemical reactions using modulated photothermal radiometry (MPR). The thermal conductivities of two TCMs, namely, calcium hydroxide (Ca(OH)2) and Ba0.15Sr0.85FeO3−δ (BSF1585), were measured as a function of temperature and time using the MPR technique. The measured thermal conductivities were correlated to the reaction. The work has two significant contributions to the research communities. First, it provides a non-invasive diagnostic tool for monitoring the thermal transport properties of TCMs that can potentially be a high-throughput measurement technique conducive to optimizing TCMs, reactors, and related thermal systems. Second, for TCMs that show observable changes in thermal transport properties, a correlation between the measured thermal conductivity and the conversion fraction of the reaction can be established for monitoring the reaction kinetics based on thermal characterization.

The Influence of Problem Based Learning Weblog on Students Motivation and Learning Outcomes on Thermochemical

This research aims to determine the influence of weblog media using the problem-based learning model on student motivation and learning outcomes on thermochemical material. This research was conducted at SMAN 1 Percut Sei Tuan in the 2023/2024 academic year. Sample determination was carried out using a purposive sampling technique. The sample consisted of 2 classes, namely class XI-Matlanko 2 as an experimental class (30 students) which was taught using Weblog media and class The instruments used are test instruments to measure learning outcomes and non-test instruments to measure learning motivation. The results of this research indicate that there is an influence of using a weblog using a problem-based learning model on student learning motivation by testing the sig hypothesis. 0.00 < α (0.05) and there is also an influence of using a weblog using the problem-based learning model on student learning motivation with hypothesis testing sig. 0.00 < α (0.05). Apart from that, there is a correlation between learning motivation and student learning outcomes who are taught using weblog media using the problem-based learning model with sig. 0.00 < α (0.05) and Pearson correlation 0.953 with the high category.

Energy sources for poultry egg incubators’ efficiency and hatchability

Artificial incubation is needed to multiply the chicken yield especially in the upcoming economies where the provision falls short of its demand. Heat is the major factor among the indispensable requirements of successful egg incubation. Hence, the main focus of this work is to identify the sources of energy used in poultry egg incubations and to determine the hatchability rate of the poultry egg incubators based on energy source used. The method of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was used. Series of eligibility/exclusion criteria were applied: only journal articles, peer reviewed conference papers and government publications were selected; articles in English publications were chosen as well. Only papers published from April, 2022 downwards were covered. The study found that sources of energy for egg incubation are categorized into grid supply electricity, solar system, fossil fuel, biogas and thermochemical materials. From the reviewed articles, 50% identified grid-supplied electricity as energy source for poultry egg incubation and hatchability ranges from 80.9% - 98.39%. However, due to erratic nature of electricity supply and non-availability in rural areas especially in developing nations, the study recommends increased research interest on other energy sources to improve their hatchability.

A scaling rule for power output of salt hydrate tablets for thermochemical energy storage

Salt hydrates are thermochemical materials capable of storing and releasing heat through reversible reaction with water vapor. In a heat battery, salt hydrate tablets of millimeter size are necessary to ensure a sufficient permeability of the packed bed. A profound understanding of the hydration process of these tablets is required to improve their kinetic performance. In this study we show that the hydration timescale of salt tablets is transport limited and that it depends primarily on the porosity and on the driving force (Δp). From gravimetric measurements done on SrBr2·6H2O and CaC2O4 we derived the intrinsic reaction and effective diffusion coefficients (k and Deff) and found that they validate a front-diffusion limited hydration hypothesis. In particular, the obtained Deff values (0.8–4.5 mm2 s−1) only depend on the tablets' porosities. Based on these parameters, we calculated the second Damköhler number (DaII) and proved that many other hydration reactions are diffusion limited. In the case of identical structures, the power output is therefore controlled only by the driving force. Its variation could be predicted by calculation of a so-called power scaling factor (Λ) for a selection of salts. This power scaling factor depends on the enthalpy (ΔH) and entropy (ΔS) of the reaction. For a temperature output of 40 °C and at 12 mbar most hydration reactions fall in the interval 0<Λ<30 and Λ exceeds 30 only in very few cases. This parameter establishes therefore another important constraint to the selection of the most ideal salt. Suitable strategies to circumvent the diffusion limitation will lead to the development of next generation salt hydrate tablets for thermochemical energy storage.

Screening of salt hydrates and cellulose nanocrystal composites for thermochemical energy storage using life cycle assessment

Salt hydrate systems via thermochemical reactions can provide thermal storage for renewable-sourced alternatives to traditional heating systems like natural gas. In this study, we use life cycle analysis (LCA) along with the material prices to screen salts based on environmental impact and cost. Additionally, we performed LCA of producing a composite material of salt and cellulose nanocrystals (CNC) at a weight ratio of four to one. CNC is a stabilizing agent for salt. We assessed the salt-CNC composites based on a laboratory scale and scaled-up processing to identify low environmental impact formulations and to identify high environmental impact processes in the composite production. In general, lanthanum chloride, lithium hydroxide, and lithium chloride should be avoided due to high environmental impact or cost. For pure salts, our results showed magnesium sulfate, zinc sulfate, and calcium chloride are typically preferred with a close second tier of magnesium and strontium chlorides and strontium bromide. For the composite material, magnesium sulfate was preferred followed by zinc sulfate, sodium sulfide, and strontium chloride. CNC has a significant environmental impact, contributing over 50% of the environmental impact for these composites. Therefore, CNC production with lower environmental impacts needs to be pursued. In composite production, the environmental impact of mixing and sonication can be reduced by scaling production. However, drying remains a high-impact process. These results can help guide salt selection for other salt-based thermochemical materials and further development of the salt-CNC composite.

Identification of Students' Misconceptions and Understanding on Thermochemistry Material with Four-Tier Multiple-Choice Tests

The delivery of chemistry learning lacking meaning and coherence is often associated with the occurrence of misconceptions. These misconceptions when not detected from the start, may persist and affect the understanding of subsequent materials. Therefore, this research aimed to identify misconceptions and understanding of concepts among students, with a focus on factors causing misconceptions about thermochemical materials. A quantitative descriptive approach was used with the four-tier multiple-choice test and questionnaire instruments. The samples comprised students in class XI Science at SMA Kawung 1 Surabaya. The results showed a profile of misconceptions about thermochemical material consisting of system and environment sub-concepts, types of systems, endothermic and exothermic reactions, types of enthalpy, as well as changes in reaction enthalpy. About 15% of students understood the concept, 31% had misconceptions, and 54% did not understand. Factors that caused misconceptions included poor understanding of the material, media used, teachers or methods, and learning resources

Microstructural changes in thermochemical heat storage material over cycles: Insights from micro-X-ray computed tomography

This paper studies the effect of successive (de)hydration cycles on the structure of potassium carbonate K2CO3·1.5H2O grains for low-temperature heat storage applications. Such structural changes are caused by exposure of the salt to water vapor or removal of water from it, accompanied by successive swelling and shrinkage. Understanding the material's internal structure is key to predicting its behaviour and optimizing its design. However, due to the simultaneous and persistent occurrence of structural changes and transport mechanisms throughout the process, gaining a complete understanding of the phenomenon can be challenging.Unlike conventional experimental approaches and two-dimensional imaging techniques used for porosity assessment, our study showcases the qualitative and quantitative alterations in the porosity and microstructure of potassium carbonate. This analysis is achieved by using Micro-X-ray computed tomography (Micro-CT). The study focuses on the impact of cycling on grain microstructure, investigating pore volume distribution, radial variation of pore sizes, and density of individual grains. It was noted that the porosity increased from 6.4 % to 19.7 % after seven cycles. Initially, we observed a greater number of pores in the core of the uncycled salt grain. However, after cycling, we noticed a more even distribution, with a higher number of pores in the outer region of the grain, which caused a radial change in porosity. Lastly, this research provides the intrinsic and apparent densities of both non-cycled and cycled potassium carbonate specimens.Micro-CT is a good tool for a better understanding of changes in thermochemical material at a structural level. Calculation of porosity provided a pathway to calculate apparent and intrinsic density. The demonstrated method can be used for a wide range of salt hydrates, enhancing the scope and applicability of this study in the field of low-temperature heat storage applications. Additionally, it gives the measuring parameter needed to calculate energy density and change in volume during the reaction.

Development of HOTS (High Order Thinking Skill) Question Instrument on Thermochemistry Material

This study aims to make High Order Thinking Skill (HOTS) items in the form of multiple-choice types of thermochemistry material for SMA/MA. The development of the HOTS question instrument was carried out to produce valid and reliable question items. The HOTS question instrument development method uses the Mc development model. Intire. Data results in development research can be carried out using rater validation and test results. Based on the results of the rater, it can be stated that the items are feasible to test by looking at the average value of validity, which is 0.727 so that they are included in the high category by looking at aspects, namely material, construction and language aspects. Based on the calculation of the results by producing 15 questions with thermochemical material for SMA/MA which are valid with the criteria for the average level of difficulty, namely (0.584), the criteria for discriminating power of the average questions, namely (0.576) with the criteria for the average validity test, namely (0.493) reliability criteria with an average of (0.686). The conclusion obtained from the data is that the HOTS question instrument can be declared suitable for student use.

Experimental validation of thermochemical water-sorption materials for thermal energy storage: Building application

Salt hydrates for seasonal heat storage have emerged as an important research topic due to their potential to fulfil the heat demand in the residential and commercial building sector. However, the research undertaken has not yet covered key aspects of their fundamental thermal behaviour understanding e.g. experimentally validation, characterisation methodologies or material screening. The present investigation is aimed to identify promising thermochemical materials in the temperature range of 25–150°C, which are suitable for building applications and waste heat recovery. A list of ten salt hydrates has been screened through an experimental validation, which was developed and optimized for the specific working conditions. The salt hydrates were tested under operational conditions and key properties are assessed (thermal conductivity, specific heat, volume change, etc). Different case studies were used to narrow down to a list of final salts candidates under three theoretical working conditions scenarios for both open and closed systems. The cases of study prioritised high energy density (after one hydration/dehydration cycle), acceptable volume expansion and stability, which led to the final candidates. Magnesium sulphate was selected in the case of high energy density (>2 MJ/m3) and low cost (1 €/MJ), when lowering the energy density to 1 MJ/m3 calcium sulphate and copper sulphate were revealed as promising candidates for open and closed systems. While calcium nitrate was identified as a candidate along with magnesium sulphate when considering closed systems.

Effects evaluation of Fin layouts and configurations on discharging performance of double-pipe thermochemical energy storage reactor

Thermochemical energy storage (TCES) based on hydrated salts is gaining popularity because it can provide high storage capacity at low costs. It is critical to improving heat storage efficiency and capacity due to technical challenges such as low thermal conductivity of thermochemical materials (TCMs) and poor mass transfer. The reversible reaction of strontium bromide monohydrate (SrBr2·H2O) and water vapor forming strontium bromide hexahydrate (SrBr2·6H2O) for TCES is used in numerical simulation, aiming to investigate the discharging performance of a double-pipe closed TCES reactor considering the influences of fin layouts (radial and longitudinal fins) by evaluating several indicators such as the reaction time and outlet temperature. The results show that the use of fins can improve the exothermic process. The discharging time of the reactor with upward L-shaped fins is reduced by 8.6% for radial fins and by 8.9% for the reactor with four longitudinal fins. The addition of fins expands the heat transfer area and makes the hydration rate of TCM around fins significantly higher than other parts. The Taguchi method is adopted to optimize the structure parameters of case 7 as it has the highest heat transfer amount of heat transfer fluid (HTF), and the optimal combination (A (fin number) = 4, B (fin extension length) = 20 mm, C (fin thickness) = 2 mm) increases the peak value of average outlet temperature by 1.47% and the heat exchange efficiency by 4.7% compared with case 7.

Validity of Digital Comics to Train Metacognitive Skills on Thermochemical Materials

Validity of Digital Comics to Train Metacognitive Skills on Thermochemical Materials

The Validity and Practicality of the SETS-Based (Science, Environment, Technology, and Society) Interactive E-Book of Thermochemistry

Validity and practicality are important elements in an e-book because it shows the accuracy and feasibility of the teaching material before it is used. This study aimed to determine the validity and practicality of teaching materials in interactive e-books based on SETS (Science, Environment, Technology, and Society) on thermochemical materials. The validity and practicality of the e-book are essential to study as the teaching materials developed are suitable for use in the learning process. This interactive e-book was developed through several stages using the DDE model development by Richey, Klein, and Nelson combined with 4STMD (Four Steps Teaching Material Development). Two validations were carried out, namely content validation and media validation. Both validations are in the very valid category. The practical aspect was obtained from a limited trial on teachers and students in a private school in Makassar. The test results on the teacher are in a good category, and the test results on the students are in the good category. The validity and practicality of the e-book show that this teaching material is feasible to use.

Pengembangan Instrumen Tes Kimia Berbasis Literasi Sains untuk Mengukur Literasi Sains Siswa

The purpose of this study was to develop a scientific literacy-based test instrument to measure students' scientific literacy at SMA Negeri 9 Bengkulu City in thermochemistry material. The development model used is the ADDIE model (Analysis, Design, Development, Implementation, Evaluation). The research subjects were classes XI MIPA 3 and XI MIPA 2 at SMA Negeri 9 Bengkulu City for the academic year 2022/2023 which were selected based on a purposive sampling technique with a population of 3 classes, which was then subjected to a homogeneity test so that a homogeneous class was obtained, namely class XI MIPA 2 for large scale test and XI MIPA 3 for small scale test. The research period starts from January to September 2022. The research data was obtained from interviews, expert validation sheets, empirical test analysis, reliability, level of difficulty, discriminating power, and analysis of students' scientific literacy levels. The number of instruments developed is 6 items in the form of essays. The research results were obtained using the Ministep application, so that the items developed were declared valid by the validator with a CVR (Content Validity Ratio) value of at least 0.78 for each question, and the CVI (Content Validity Text) value obtained was 0. 94 with very good category. The results of the empirical validity test were carried out on 15 students of class XI MIPA 3 and obtained 8 valid questions. The developed scientific literacy-based test instrument has a reliability value of 0.85 in the very good reliability category so that it can be used to measure students' scientific literacy level. The results of implementing the development of scientific literacy-based test instruments obtained 1 student who had a high level of scientific literacy, 2 students who had a moderate level of scientific literacy, and 23 students with a scientific literacy level at the nominal scientific Literacy level. The results of the development of scientific literacy-based test instruments have proven to be accurate and reliable so that they can be used to measure students' scientific literacy, especially in thermochemical material.&#x0D; Keywords: development, chemical test instrumen, scientific literacy, and thermochemistry

Latest Advances in Thermal Energy Storage for Solar Plants

To address the growing problem of pollution and global warming, it is necessary to steer the development of innovative technologies towards systems with minimal carbon dioxide production. Thermal storage plays a crucial role in solar systems as it bridges the gap between resource availability and energy demand, thereby enhancing the economic viability of the system and ensuring energy continuity during periods of usage. Thermal energy storage methods consist of sensible heat storage, which involves storing energy using temperature differences; latent heat storage, which utilizes the latent heat of phase change materials; and thermochemical heat storage, which utilizes reversible chemical reactions through thermochemical materials. The objective of this review paper is to explore significant research contributions that focus on practical applications and scientific aspects of thermal energy storage materials and procedures. For each type of storage, different materials have been examined, taking into consideration the most recent studies, both for medium and long-term storage and, when possible, comparing methodologies for the same purpose. It has been observed that TCHS systems have the potential to reduce the volume of chemical storage tanks by 34 times using chemical reactions. Among the SHS materials, water, molten salts, and graphite exhibit the highest energy density, with graphite also possessing remarkable thermal conductivity. Nanoparticles can enhance the thermophysical properties of TES materials by increasing their thermal conductivity and wettability and improving intermolecular characteristics. The use of biobased PCMs for applications that do not require very high temperatures allows for maximizing the efficiency of such storage systems.