Thermochemical Materials Research Articles

Analysis of a novel constructal fin tree embedded thermochemical energy storage for buildings applications

Because of their potential for long-term and loss-free thermal energy storage, thermochemical materials are attractive candidates for storing solar thermal energy in buildings applications. A drawback, however, is that of poor heat transport in the thermochemical material bed during charging and discharging. This study presents a novel thermochemical energy storage system with embedded constructal fin tree structure to enhance the discharge process. The influence of the constructal fin design parameters on the energy storage density and levelized cost of storage is studied to establish design envelopes that satisfy the U.S. Department of Energy Buildings Thermal Energy Storage program requirements, which include a round-trip thermal energy storage density of more than 80 kWh/m3 and storage cost less than $15/kWh. The study reports optimum designs of the constructal fin tree enhanced thermochemical reactor bed based on minimum levelized cost of storage and maximum energy storage density for building-integrated thermal energy storage applications.

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.

A structured procedure for the selection of thermal energy storage options for utilization and conversion of industrial waste heat

Thermal energy storage is a key enabling technology for the recovery and valorisation of industrial waste heat. Nevertheless, there is a wide gap between the variety of heat storage options investigated and the recurrent few types virtually implemented in the industries. To take advantage of a wider spectrum of solutions, a structured procedure is proposed in this work for the selection of storage material and layout. The algorithm developed consists of a preliminary storage design followed by a performance estimation of the overall system where the heat storage is integrated. The preliminary design allows a first screening and ranking of sensible, latent or thermochemical materials using a quasi-stationary approach. The performance estimation leads to the final selection of the heat storage system, which is based on the analysis of the dynamic thermal response of the heat storage along with physically based or input-output models for the load. The algorithm is applied to improve the heat recovery of a discontinuous and fluctuating flue gas at medium temperature from a steel industry, targeting the production of process steam or electricity. The results show that the integration of a packed bed heat storage, either of the sensible or latent type, allows the highest amount of steam to be generated in the discharging. Moreover, the combination of the same heat storage with an organic Rankine cycle or the Kalina cycle results in the highest amount of generated electricity. The investment in a packed bed rock storage was found to result in payback times of about seven years, whereas tank-based storage units appear not profitable due to the high cost of the silicone oil.

IMPLEMENTATION OF THERMOCHEMISTRY LEARNING VIDEO FOR GRADE XI STUDENTS

A research has been conducted entitled "The Application of Thermochemistry Learning Videos for Class XI MIA-I MAN 6 Aceh Besar Students". The purpose of this study was to analyze student activities, learning outcomes, and student responses after the application of thermochemistry learning video in class XI MIA-I MAN 6 Aceh Besar. This study uses an approach with a descriptive type of research. The sample in this study were students of class XI MIA-1 MAN 6 Aceh Besar. The results show participant activity increased significantly as seen in the percentage of activity from the first meeting to the fourth meeting in a row, which was 76.52%; 83.33% ; 85.83% and 92.42%. Learning outcomes increased and achieved classical completeness as seen from the percentage of complete learning outcomes, which was 88%. The response of students to the application of learning video media on thermochemical material also showed a positive response with a percentage of 88.2%. Thus, it can be said that student learning outcomes through the application of learning video media have increased and have taken place classically, student activities have also increased at each meeting, and students have responded positively to the application of learning video media.

Pengaruh Penggunaan Video Pembelajaran Berbasis Problem Based Learning (PBI) terhadap Hasil Belajar Siswa Kelas XI SMA pada Materi Termokimia

Problem Based Learning (PBL) learning model is a set of learning activities that emphasize the process of solving problems faced scientifically. The use of video media can help students' learning process and will have a big impact on the learning outcomes of thermochemical material because almost everyone, from children to the elderly, now has a smartphone. In addition to learning videos, powerpoint is one of the learning media that can help students who have learning difficulties. The purpose of this study was to determine whether the thermochemistry learning outcomes taught using PBL-based learning videos were higher than the thermochemistry learning outcomes taught using PBLbased PPT. This study involved the experimental class I and the experimental class II. From the results of the study, the average pre-test for the experimental class I was 41,95 and the experimental class II was 41.44. After being treated with learning in both experimental classes, post-test was then recommended to determine learning outcomes, the post-test average of experimental class I was 83.14 and experimental class II was 78.44. The results showed that the experimental class I which was taught by learning video media and the PBL model was higher than the learning outcomes of the experimental class II which was taught by the powerpoint media and the PBL model. It can be concluded that the use of instructional video media, learning outcomes are higher than the use of powerpoint media.

Pengaruh Penggunaan Modul dalam Pembelajaran Kimia Berbasis Proyek terhadap Hasil Belajar Siswa Kelas XI Semester 1 pada Materi Termokimia

This research aims to: (1) To know the effect of using modules in project-based chemistry learning on student learning outcomes in class XI semester 1 on thermochemical material. (2) To know the effectiveness of using the module in project-based chemistry learning in the learning process of class XI semester 1 students on thermochemical material. (3) To find out the response of class XI semester 1 students to learning by using project-based modules on thermochemical material. The population of this research is all students of class XI IPA SMA Negeri 14 Medan T.A 2021/2022. The sample in this study was taken using the purposive sampling technique, then took 2 sample classes as the experimental class and the control class. Class XI MIPA 4 is used as an experimental class which is taught through the use of project-based modules while class XI MIPA 2 is a control class with conventional learning. The instrument used in this study was a test of thermochemical material chemistry learning outcomes in the form of multiple choice as many as 25 valid and reliable questions (0.8570). The data analysis technique for hypothesis testing is a one-sample t-test (right side). The data obtained from student learning outcomes in the experimental class is 82.59 and in the experimental class is 68.00. From hypothesis testing with a significance level of 0.05, it was obtained t value > critical t value (6.441 > 1.997), so that in this study H0 was rejected and Ha was accepted. Thus, it is found that there is a significant effect of using modules in project-based chemistry learning on the learning outcomes of class XI semester 1 students on thermochemical material.

Enhancement of heat and mass transfer of potassium carbonate-based thermochemical materials for thermal energy storage

Salt hydrates are ideal for long-term thermochemical heat storage in a built environment, where K2CO3 is considered a promising thermochemical heat storage material. This class of materials continues to encounter certain technical bottlenecks in practical applications, and the enhancement of heat and mass transfer is a key challenge. Composite materials are a promising method to address this challenge because heat and mass transfer are coupled and material-dependent. In this study, a novel K2CO3-based composite material was synthesized from expanded graphite (EG), K2CO3, and octylphenol polyoxyethylene(10) ether (OP-10), and its structural information, reaction kinetic properties, thermodynamic properties, and cycling stability were determined. The results showed that the use of EG with OP-10 significantly enhanced mass and heat transfer. Compared to pure K2CO3, the thermal conductivities of the composites were increased by 9–15 times and their half-conversion time was shortened by approximately 3/4–4/5, indicating that their mass and heat transfer capacities were effectively improved. The mass and volume energy storage densities (ESDs) of K2CO3-based composites reached 429–563 kJ⋅kg−1 and 138–216 kWh⋅m−3, respectively, and these values depended on the content of K2CO3. In addition, the cycling stability results indicated that these K2CO3-based composites performed well and were suitable for medium-to-low-temperature thermochemical thermal storage applications.

Development of Android-Based Learning Media Applications on Thermochemical materials for Class XI Senior High School Students

Development of Android-Based Learning Media Applications on Thermochemical materials for Class XI Senior High School Students

Thermodynamic equilibrium and kinetic study of lanthanum chloride heptahydrate dehydration for thermal energy storage

In the past decade, thermochemical materials have gained attention as promising options for heat storage. Compared to sensible heat storage and phase change materials, thermochemical materials offer certain important advantages such as high energy density and low heat loss during the storage process. Lanthanum chloride hydrates are interesting and promising materials owing to their high energy density and application at low temperature and water-vapor pressure. The thermodynamic properties of the LaCl3–H2O system and dehydration kinetic of LaCl3⋅7H2O are investigated using coupled thermogravimetry and differential scanning calorimetry under a controlled humidity atmosphere and X-ray diffraction. As the literature on the LaCl3 thermodynamic equilibrium is inconsistent, the phase diagram is experimentally determined. The findings of the first part of the study are presented in the form of a reliable phase diagram. From a kinetic point of view, it has been determined that the dehydration of lanthanum sulfate heptahydrate can be analyzed using the shrinking core model, where the growth of a new phase alone is the rate-determining step. The areic reactivity of growth decreases with the increase in water-vapor pressure and increases with the increase in temperature. The mechanism of the dehydration reaction is presented, in which the desorption of water molecules is the rate-determining step.

Optimal thermochemical material selection for a hybrid thermal energy storage system for low temperature applications using multi criteria optimization technique

Thermochemical energy storage is one of the viable solutions for the increasing energy demand because of its high energy density and less heat loss during the storage phase comparing to the other methods. The selection of proper thermochemical material (TCM) is then become important in this type of thermal energy storage. This paper describes the use of Multi Criteria Decision Making (MCDM) techniques to select the optimum thermochemical material from the alternatives to be used for low temperature (<150 °C) energy storage. The best thermochemical material is selected using different MCDM techniques like simple additive method, weighted product model, Technique for Order Preference by Similarity to Ideal Solution, Evaluation based on Distance from Average Solution, Multi-Objective Optimization on The Basis of Ratio Analysis, Preference Ranking Organization Method for Enrichment Evaluation, and VIKOR. The criteria weights for optimization are evaluated by different methods such as mean weight method, standard deviation method, analytic hierarchy process, Entropy method, criteria importance through inter-criteria correlation and Compromised weight method. In all MCDM-Weighting method combinations MgCl2·6H2O ranked first (optimum material) and Na2S·9H2O ranked last. The ranking obtained from various MCDM-weighting method combination are compared with each other using average Spearman rank correlation coefficient and found that Evaluation based on Distance from Average Solution (EDAS), Multi-Objective Optimization on The Basis of Ratio Analysis (MOORA), Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE II) and VIKOR with AHP weighting method have the highest correlation coefficient (rs = 0.9857) and CRITIC-VIKOR method (rs = 0.5143) has the lowest correlation coefficient.

Hygroscopic additive-modified magnesium sulfate thermochemical material construction and heat transfer numerical simulation for low temperature energy storage.

In this research, the core objective is to explore the effect of super-absorbent polymer material (poly(sodium acrylate)) on the heat storage performance of magnesium sulfate and to investigate the heat transfer behavior of 13X-zeolite, nano-aluminum oxide (nano-Al2O3) and poly(sodium acrylate) modified magnesium sulfate in a reactor. Finally it provides support for future material and reactor design. All characterizations and performance tests were done in the laboratory and a numerical simulation method was used to investigate the heat transfer behavior of the reactor. Through hydrothermal treatment, bulk MgSO4·6H2O was changed into nanoparticles (200–500 nm) when composited with poly(sodium acrylate), 13X-zeolite and nano-Al2O3. Among these materials, MgSO4·6H2O shows the highest activation energy (36.8 kJ mol−1) and the lowest energy density (325 kJ kg−1). The activation energy and heat storage energy density of nano-Al2O3 modified composite material MA-1 are 28.5 kJ mol−1 and 1305 kJ kg−1, respectively. Poly(sodium acrylate) modified composite material, MPSA-3, shows good heat storage energy density (1100 kJ kg−1) and the lowest activation energy (22.3 kJ mol−1) due its high water-absorbing rate and dispersing effect. 13X-zeolite modified composite material MZ-2 shows lower activation energy (32.4 kJ mol−1) and the highest heat storage density (1411 kJ kg−1), which is 4.3 times higher than that of pure magnesium sulfate hexahydrate. According to the heat transfer numerical simulation, hygroscopic additives could prominently change the temperature distribution in the reactor and efficiently release heat to the thermal load side. The experimental and numerical simulation temperatures are similar. This indicates that the result of the numerical simulation is very close to the actual heat transfer behavior. This reactor could output heat at around 50 °C and absorb heat in the range of 100–200 °C. All these results further prove the strategy that thermochemical nanomaterial synthesis technology combined with material-reactor heat transfer numerical simulation is feasible for future material and reactor design.

VALIDATION OF THERMOCHEMISTRY SUPPLEMENT BOOK BASED PROBLEM SOLVING TO TRAIN STUDENTS METACOGNITIVE SKILLS

This research aims to know validity of thermochemistry suplement book based problem solving to train students metacognitive skills includes the content and construct. Content validity includes the suitability of the material and questions. Construct validity includes presentation and readability techniques. Problem solving model has 4 steps, that are understanding the problem, devising a plan, carrying out the plan, and lock back. Metacognitive skills consist of 3 components, namely planning, monitoring, and evaluating. The type of research used is the Research and Development (R&amp;D) from Sugiyono. The supplement book was assessed by 3 experts in the field of chemical education using a validation instrument. The results showed that a chemical supplement book based on problem solving to train students' metacognitive skills on thermochemical material was very good with a score of 91.6% in content validation and 84.9% in construct validation.

Pemetaan Level Literasi Kimia Peserta Didik Kelas XI MIPA di SMAN 1 Lubuk Basung pada Materi Termokimia dengan Model Rasch

This study aims to analyse the mapping of chemical literacy levels of students in class XI MIPA at SMAN 1 Lubuk Basung on thermochemical material using the Rasch model according to the scientific literacy framework adapted by Shwartz. This study is a quantitative study using a sample of 50 students of class XI MIPA. The data is obtained from a chemical literacy test, then the data is analysed using the Rasch model. The results showed that students with the highest abilities have the right answers but have not been able to define the concepts and understanding is limited, meanwhile students with the lowest ability have wrong or blank answers. Thus, it was concluded, students with the highest abilities have a functional scientific literacy level on difficult items and students with the lowest abilities have a scientific literacy level.

Salt hydrate–based gas-solid thermochemical energy storage: Current progress, challenges, and perspectives

Due to the prominent advantages of high energy density and long-term energy conservation ability, salt hydrate-based gas-solid thermochemical energy storage (TCES) is a promising technology for effectively employing low-grade energy such as industrial waste heat and minimising fossil fuel-based sources depletion. As an innovative thermal energy storage technology that has drawn great attention from scholars in recent years, it still remains in the stage of a laboratory-scale investigation. This study establishes a reasonable classification of salt hydrates-based TCES systems, discusses the properties and performance regulation strategies of materials, types of reactors, applications, heat and mass transfer process, reaction mechanisms, and also provides critical comments and outlooks on this adsorption TCES technology. It is comprehensively elaborated and evaluated in the following steps.(i) The development of various thermochemical materials (TCMs), including pure salts, mixtures of salt hydrates, and composite TCMs of salt/matrix, is summarised and assessed in detail from the perspectives of thermochemical performances such as ESD and cyclability.(ii) The progress of the conceptual design of the reactor and prototype used for vapour/salt gas-solid reaction are presented and analysed.(iii) The existing theoretical models ranging from the views of microcosmic molecular dynamics to macrocosmic reaction kinetics are discussed.(iv) Additionally, the existing challenges regarding salt hydrate-based TCES technology are identified, and the prospects are also provided.This review enables researchers to timely grasp the latest advancements and thus may provide some rewarding insights for future investigations of salt hydrate-based gas-solid TCES and facilitate scholars to achieve better improvements.

The Profile of Students’ Self-Efficacy in Using Chemdroid Media in Thermochemistry Topics

Self-efficacy is one of the factors that affect learning achievement. This study has the aim of analyzing the self-efficacy profile of students in learning using Chemdroid (Chemistry on Android) media. This media is an android-based media for Thermochemical material. This research is descriptive research with a quantitative approach. The classes used in this study were 2 classes with 60 students. Both are randomly selected. The first class is the control class (C-Class) which carries out hybrid learning, as usual, namely face-to-face in class and online learning using WhatsApp groups. The second class is the experimental class (E-Class) with face-to-face in class and using Chemdroid media. The learning time and the teacher in this study were the same. The instrument used is a self-efficacy measuring instrument consisting of 3 main aspects with 22 statements adapted from previous research. The results of the study were then analyzed and categorized into 5 categories. The results obtained indicate that the profile of students’ self-efficacy of E-Class students is higher than other class.

Pengembangan E-Modul Terintegrasi Media Berbasis Adobe Flash CS6 Untuk Meningkatkan Kemampuan Pemecahan Masalah Kimia Mahasiswa

Supporting the implementation of an effective learning process cannot be separated from the use of teaching materials. Improving the quality of the learning process in higher education can be done with various strategies and one alternative that can be taken is the development of teaching materials. This study aims to develop an integrated e-module based on Adobe Flash CS6 media to improve students' chemistry problem solving skills on thermochemical material. The development model used refers to the ADDIE development model. Adobe Flash CS6-based integrated media e-module is designed to be accessible and downloadable by students online. The developed Adobe Flash CS6-based media-integrated e-module has been declared valid and proven to be effective in improving students' chemistry problem solving abilities on thermochemical materials.

Pengembangan Modul Pembelajaran Kimia Berbasis Proyek Pada Pokok Bahasan Termokimia Untuk Kelas XI SMA

This study aims to 1) find out whether the chemistry teaching materials used in high school on thermochemistry materials have been project-based, 2) find out whether the thermochemistry learning modules developed have met project-based studies, 3) find out whether the thermochemistry teaching materials developed have met the module requirements, 4) find out whether the chemistry learning module developed on thermochemical material is in accordance with the criteria set by the BSNP, and 5) find out how students respond to aspects of the appearance, material, and benefits of project-based thermochemical modules. The research method is Research and Development (R&amp;D) with the ADDIE development model. The sample set in this research is 1) Chemistry Lecturer at State University of Medan as many as 3 people, 2) Chemistry teacher at SMA Negeri 2 Percut Sei Tuan as many as 3 people, and 3) Class XI science students at SMA Negeri 2 Percut Sei Tuan in 1 class with 20 students. person. The results of the analysis of teaching materials in schools show that books A and C are not based on Project Based Learning with a value of 1.44. Meanwhile book B deserves to be a Project Based Learning book with a value of 2.66. The results of the validation (syntax) of the PjBL model in the module obtained a content aspect score of 3.12 with appropriate criteria. In terms of the activity aspect, it has a score of 3.30, the condition aspect has a score of 3.50, and the outcome aspect has a score of 3.50 and the criteria are very feasible. The results of the BSNP standardization obtained a content feasibility value of 2.98 with appropriate criteria; and presentation feasibility 3.36; chart feasibility 3.33; the feasibility of the language is 3.36 with very feasible criteria so that the score of the four aspects of eligibility is 3.26 with very feasible criteria. It can be concluded that the developed module is suitable for use as teaching materials.

Pengembangan Lembar Kerja Siswa (LKS) Berbasis Model Pembelajaran Inkuiri Terbimbing Pada Materi Termokimia

This study aims to determine the feasibility of the worksheets student based on the BSNP criteria and to find out the responses of students to the designed worksheets. The method in this research uses the method of Research and Development (R&amp;D) according to the Borg and Gall stages. The research subjects were worksheets based on guided inquiry learning models. The object of research is the thermochemical material. The results showed that the worksheets student that had been compiled had met the eligibility criteria according to the BSNP standards based on the content feasibility aspect, the presentation feasibility aspect, and the language feasibility aspect, which was obtained an average percentage of 88.55% with valid / feasible criteria and based on the feasibility aspect of graphic -the average percentage of 87.41% with valid / feasible criteria. As for the results of student responses to the designed worksheets is very high with an average percentage of 88.60%.

Optimized design of Ca-based thermochemical heat storage materials for concentrated solar power

Ca-Looping concentrated solar power with direct radiation absorption mode is promising, provided that the low light absorption of CaCO3/CaO can be solved. In this work, Ca-based thermochemical materials (CTMs) doped with Fe and Mn elements were synthesized by the sol-gel method. The added Fe and Mn elements increase the absorption of CTMs, while also effectively improving cyclic stability. Calcination experiments show that Ca0.15Fe2.85O4 can be used as additional materials to improve the absorption of CaCO3/CaO, and in particular, the near IR region. Additional findings suggest that morphology and cyclic stability of the materials are closely related. The porosity and pore size of CaCO3/CaO was also controlled by adjusting the amount of citric acid used during processing.

Independence of Learning and Achievement of Learners' Cognitive Abilities in Thermochemical Materials through the Application of Flipped Classroom

The utilization of online media such as learning videos, e-books, e-libraries, and virtual laboratories as a source of independent learning by learners is still very low, as a result of which teachers are still the main source of learning. This shows the low independence of learning learners, even though independence is one-factor affecting learning achievement. The correct learning methods can increase the independence of learning learners, one of which is by applying flipped classrooms. This research aims to find out the effect of the application of flipped classrooms on learning independence and cognitive achievement of learners in thermochemical materials as well as the correlation of learning independence with the achievement of cognitive abilities of learners. This study is an experimental study with the design of two groups at random. The measuring instrument used is a matter of postest and learning independence questionnaire. The research data were analyzed using the SPSS for Windows program. The results found that learning independence and better achievement of cognitive abilities were shown in the group that applied the class upside down. There was a significant positive relationship between the achievement of cognitive ability and the independence of learning in both groups, both in classes that applied classes in reverse and in classes that did not apply inverse classes.