Sustainable Heat Research Articles

The First Fifth-Generation District Heating and Cooling System in Kazakhstan: Planning and Design

This paper focuses on the potential for integrating Geographic Information System (GIS) software into Fifth-Generation District Heating and Cooling (5GDHC) systems to promote efficient and sustainable energy management, particularly in Kazakhstan. By reviewing the key literature, we identify three main areas where GIS software enhances the planning of 5GDHC systems: decision-making in the context of energy market regulations, operational data utilization, and modeling/simulations for technical design. The technical design emphasizes the role of heat pumps, ultra-low temperature district heating (ULTDH) networks, and end-user buildings. Previous research has explored various methodologies for integrating network and demand-side strategies, developing sustainable district heating and cooling (DHC) systems, and mapping urban areas suitable for DHC deployment. However, none has presented an open-source model incorporating GIS-based decision-making in designing 5GDHC systems. This study, for the first time, addresses this gap through a case study conducted in the Northern Industrial Zone of Karaganda, Kazakhstan, demonstrating how GIS-enhanced modeling can be effectively applied in a developing, industry-driven economy. We outline the mathematical framework for comparing existing simulation tools and developing a custom model suited to the region’s needs. Additionally, we discuss validation and calibration methods, which remain underexplored in the current literature. The proposed model incorporates waste heat recovery from local sources, including nearby wastewater treatment plants, showcasing a sustainable energy solution for the industrial park. The results indicate that a well-structured 5GDHC system, supported by GIS tools, can markedly enhance energy efficiency and sustainability, presenting a scalable and adaptable approach for other regions in Kazakhstan and beyond.

Life cycle assessment and thermodynamic performance of biomass-based combined cogeneration

Abstract This study presents a thermodynamic and life cycle analysis of a biomass-based integrated energy system, comprising a biomass gasification cycle, a steam Rankine cycle, and an ammonia fluid Organic Rankine cycle. The primary objective of the system is to efficiently convert olive husk, a sustainable biomass source, into electricity and heating. The gasification process generates syngas, which fuels a gas turbine, producing high-temperature exhaust that drives a Rankine cycle. The thermodynamic analysis indicates that the overall system achieves an energy efficiency of 20.85% and an exergy efficiency of 11.70%. The Rankine cycle exhibits an energy efficiency of 23.91%, while the Organic Rankine cycle demonstrates a higher exergy efficiency of 68.87%. Parametric studies reveal that increasing the combustion chamber temperature significantly enhances system efficiency and output, with energy efficiency rising linearly as the temperature increases from 800 °C to 1000 °C. Additionally, the analysis emphasizes the importance of the compressor's compression ratio on system performance. A life cycle assessment conducted using the ReCiPe methodology evaluates the environmental impact of the system throughout its lifecycle, revealing critical insights into its sustainability. This comprehensive evaluation highlights the potential of utilizing agricultural waste, such as olive husk, to produce renewable energy, thereby supporting environmental sustainability and waste management goals. The findings underscore the viability of the proposed system for enhancing energy production while minimizing environmental impacts, making it a promising solution for renewable energy generation in regions with abundant biomass resources.

Innovative Solutions for Sustainable Space Heating: Integrating Solar Air Heaters and Low-Cost Retrofitting Windows for Hilly Region of Kashmir

The Kashmir valley experiences a moderate climate, characterized by cool springs and autumns, mild summers, and cold winters, necessitating heating for approximately 5-6 months annually. Due to unreliable power supply, traditional heating methods such as gas heaters, wood fires, or Kangri's are often relied upon, despite their adverse health and environmental impacts due to emissions of toxic gases. Therefore, there is a need of transition towards non-conventional energy sources. Solar air heaters emerge as a viable option, converting solar radiation into thermal heat which is then delivered to living or working spaces. In addition to minimizing energy requirements for space heating, strategies to reduce heat loss can further enhance energy efficiency. Developing low-cost retrofit window solutions to improve the thermal efficiency of existing windows proves instrumental in this regard. Retrofit windows, designed to fit into existing frames, improve insulation and reduce energy loss without requiring costly renovations. The primary aim of these retrofit windows is to optimize energy efficiency affordably, minimizing heat transfer and preventing air leaks, thereby reducing energy consumption and utility bills while enhancing indoor comfort by maintaining stable temperatures. The several tests were conducted on a thermally insulated test room of size 12*8*10 cubic feet room for solar air heaters under various atmospheric conditions gives a temperature increases of up to 10°C within one hour under different parameters. Furthermore, retrofitting demonstrated a 45.69% reduction in energy requirements at a very affordable cost.

Comparative Thermal Performance Analysis of Coaxial Versus Conventional Pipes in District Heating Distribution Systems

District heating systems play a pivotal role in providing efficient and sustainable heating solutions for urban areas. In this sense, district heating systems that use geothermal resources have been gaining prominence in recent years, due to the non-intermittent nature of their application, among many other reasons. The present study investigates the thermal performance of novel coaxial pipes in comparison to conventional pipes within district heating distribution networks supplied by geothermal energy. Through experimental simulation and analysis, key thermal parameters such as heat transfer efficiency, thermal losses, and overall system effectiveness are evaluated through laboratory tests developed on a scale model. Experimental analysis concludes that, at a laboratory scale, heat energy efficiency can be improved by around 37% regarding the traditional geothermal distribution network. This improvement translates into a significant economic and environmental impact that has a direct influence on the viability of this type of system in different application scenarios. The results highlight the potential benefits of coaxial pipe designs in enhancing heat transfer efficiency and minimizing thermal losses, thus offering insights for optimizing geothermal district heating infrastructure for improved energy efficiency and sustainability. The novelty of this study lies in the innovative design and experimental validation of coaxial pipes, which demonstrate a 37% improvement in heat energy efficiency over conventional pipe designs in geothermal district heating systems, offering a breakthrough in optimizing heat transfer and minimizing thermal losses.

A Simulation-Assisted Field Investigation on Control System Upgrades for a Sustainable Heat Pump Heating

Heat pump-based renewable energy and waste heat recycling have become a mainstay of sustainable heating. Still, configuring an effective control system for these purposes remains a worthwhile research topic. In this study, a Smith-predictor-based fractional-order PID cascade control system was fitted into an actual clean heating renovation project and an advanced fireworks algorithm was used to tune the structural parameters of the controllers adaptively. Specifically, three improvements in the fireworks algorithm, including the Cauchy mutation strategy, the adaptive explosion radius, and the elite random selection strategy, contributed to the effectiveness of the tuning process. Simulation and field investigation results demonstrated that the fitted control system counters the adverse effects of time lag, reduces overshoot, and shortens the settling time. Further, benefiting from a delicate balance between heating demand and supply, the heating system with upgraded management increases the average exergetic efficiency by 11.4% and decreases the complaint rate by 76.5%. It is worth noting that the advanced fireworks algorithm mitigates the adverse effect of capacity lag and simultaneously accelerates the optimizing and converging processes, exhibiting its comprehensive competitiveness among this study’s three intelligent optimization algorithms. Meanwhile, the forecast and regulation of the return water temperature of the heating system are independent of each other. In the future, an investigation into the implications of such independence on the control strategy and overall efficiency of the heating system, as well as how an integral predictive control structure might address this limitation, will be worthwhile.

Development of a top-lit-up-draft biomass gasifier as a sustainable heat source for effective drying of plantain slices in a cabinet dryer

This paper explored the development of a top-lit-up-draft biomass gasifier as a sustainable heat energy alternative to the traditional sun drying and the costly, unreliable heat energy sources such as grid-electricity and petrochemical fuels commonly used for cabinet dryers, especially in developing countries like Nigeria. The gasifier utilized the principle of top-lit-updraft biomass gasification system to thermochemically converts agricultural residues into clean heat energy. The designed gasifier has reactor diameter and height of 28cm and 90cm, fuel consumption rate of 55kg/hr, gasification airflow rate of 82.1m3/hr, DC fan motor of 15W, equipped with 30Ah battery power source, and capable of supplying heat energy of 260.16MJ/h. Performance testing using input variables of fuel loading (10kg-20kg), fan speed (4000rpm-6000rpm), and fuel type (palm-kernel shell, coconut shell, coconut husk, and wood shavings) assessed the gasifier responses such as fuel gasification time, flame temperature, thermal and combustion efficiencies, and carbon monoxide (CO) emission of the flame. Results revealed maximum thermal efficiency, peak flame temperature and longest gasification time of 86.02%, 8750C, and 130min respectively, when operated with palm-kernel shell at maximum fan speed and fuel loading, which emitted average CO of 1ppm lower than the least international air pollutant threshold of 9ppm. Highest combustion efficiency of 99.9% was attained using wood shavings at maximum fan speed and fuel loading. The results highlighted the potential of the gasifier as an effective heat source for drying applications, particularly for drying plantain slices in a cabinet dryer.

Interface kinetic manipulation enabling efficient and reliable Mg3Sb2 thermoelectrics

Development of efficient and reliable thermoelectric generators is vital for the sustainable utilization of energy, yet interfacial losses and failures between the thermoelectric materials and the electrodes pose a significant obstacle. Existing approaches typically rely on thermodynamic equilibrium to obtain effective interfacial barrier layers, which underestimates the critical factors of interfacial reaction and diffusion kinetics. Here, we develop a desirable barrier layer by leveraging the distinct chemical reaction activities and diffusion behaviors during sintering and operation. Titanium foil is identified as a suitable barrier layer for Mg3Sb2-based thermoelectric materials due to the creation of a highly reactive ternary MgTiSb metastable phase during sintering, which then transforms to stable binary Ti-Sb alloys during operation. Additionally, titanium foil is advantageous due to its dense structure, affordability, and ease of manufacturing. The interfacial contact resistivity reaches below 5 μΩ·cm2, resulting in a Mg3Sb2-based module efficiency of up to 11% at a temperature difference of 440 K, which exceeds that of most state-of-the-art medium-temperature thermoelectric modules. Furthermore, the robust Ti foil/Mg3(Sb,Bi)2 joints endow Mg3Sb2-based single-legs as well as modules with negligible degradation over long-term thermal cycles, thereby paving the way for efficient and sustainable waste heat recovery applications.

Recent Advances in Desiccant Materials for Energy‐Efficient and Sustainable Heat Transfer Systems

The expanding prevalence of heating, ventilation, and air conditioning (HVAC) systems, currently reliant on fossil fuel‐derived energy, necessitates energy‐saving measures to address climate change concerns. Implementing desiccants with high water vapor affinity reduces latent heat input, impacting the heat exchanger's functionality based on system and desiccant characteristics. This review analyzes the materials in solid desiccants, binders, and substrates, emphasizing advancements for enhanced heat transfer efficiency. Some notable materials explored include metal–organic frameworks, activated carbon, silica gel, polymers, and zeolite. In system level, the article discusses about the dual‐channel heat exchanger which emerges as a solution to drawbacks in existing dehumidification systems, offering higher performance and lower latent heat load in modern solid desiccant‐coated heat exchangers. Despite the environmental impact of material usage, future research should focus on sustainable materials, such as those derived from biomass or recycled sources, to maintain efficiency while minimizing waste in HVAC systems.

Engaging Communities in Energy Transitions: A Study on Attitudes Towards Sustainable Heating Technologies and the Role of Peer Effects in Southern Chile

This study investigates the role of peer effects in shaping the adoption of sustainable heating systems in two highly polluted communes in Southern Chile. Despite policies promoting cleaner alternatives, wood-burning stoves, a major source of particulate matter emissions, remain widespread. This research work addresses a critical gap in the literature by examining how peer influence—typically studied in relation to visible technologies like solar panels or electric vehicles—affects the adoption of less visible but essential sustainable heating technologies. The main objective of this study is to understand how peer networks can influence the attitudes of residents towards sustainable heating technologies in highly polluted urban environments. Employing a non-experimental, cross-sectional design with a sample of 244 participants, this study reveals that peer effects and health risk perception are significant predictors of positive attitudes towards sustainable heating systems. These findings contribute valuable insights for policymakers seeking to accelerate energy transitions in polluted regions.

Comprehensive analysis of a novel sustainable photovoltaic/thermal assisted ground source heat pump system with energy storage

The imbalance of soil heat is a significant issue hindering the sustainable operation of ground source heat pump (GSHP) systems, especially under single-mode heating conditions. To address this challenge and develop a more energy-efficient, economical, and sustainable heating system, this paper proposes a novel PV/T-GSHP-PCM (photovoltaic/thermal-ground source heat pump-phase change material) system. A simulation model of the system was developed, and its performance was thoroughly analyzed. Furthermore, the comprehensive performance of four different system coupling configurations was compared. The study concluded that the PV/T-GSHP-PCM system increases energy efficiency by 13 % and reduces operating costs by 32 % compared to conventional GSHP systems. Furthermore, the PV/T-GSHP-PCM system achieves zero energy consumption, zero operational cost, and zero carbon dioxide emissions. After 10 years of continuous operation under single-mode heating, the soil heat imbalance rate stabilized at around 7 %, the heating coefficient of performance of the system decreased by only 0.04. This system demonstrates sustainable and efficient green heating. This study provides valuable insights for advancing research on sustainable and renewable energy-based heating systems.

Investigation of a Novel Thermochemical Reactor for Medium- and Low-Temperature Heating Applications in Buildings

This research paper investigates a novel triangular honeycomb thermochemical energy storage reactor for low- and medium-temperature applications in buildings, emphasizing its potential to enhance sustainable heating. Using a validated 3D numerical model, the reactor’s performance is analyzed in depth across various configurations, focusing on key parameters such as energy storage density, pressure drop, internal air flow distribution, and round-trip efficiency. Results show that the reactor achieved an energy storage density of 872 kJ/kg and a round-trip thermal efficiency of 41.51% under optimal conditions. Additionally, the triangular honeycomb reactor (30°, 60, and 90°) configuration achieved the highest temperature lift of 48.7 °C. In a feasibility analysis for residential heating in northern China, the reactor with 30°, 60°, and 90° angles required 24.91% less volume to meet daily heating demands compared to other configurations. This study contributes valuable insights for the development of efficient, low-carbon heating solutions for low- and medium-temperature applications in buildings, offering interesting advancements in the field of thermochemical energy storage technology.

An Analytical Approach for Sustainable Greenhouse Heating in Lebanon: A Focus on Air Source Heat Pumps

Abstract In Lebanon, where economic challenges and Mediterranean climate dominate, protected cultivation methods, such as greenhouses, are widely used for sustainable agriculture. Tomatoes, with an annual production of around 250,000 tons in Lebanon, are the focus of this study. Tomato leaves require a temperature range of (18-25ºC) for optimal growth. The present study explores the potential of air-source heat pumps as a sustainable heating method. It includes a comprehensive literature review and discusses alternative heating methods. A dynamic energy model was developed after using statistical models to plot the temperature and solar radiation profiles for the worst-case scenario for heating. This energy model sizes the heat pump to maintain 18 ºC in a standard 332 m2 Quonset greenhouse with thermal polyethylene covering. The model’s validity was demonstrated by comparing its temperature profiles with a study conducted in West Bengal, India. The results indicate the adequate size for the studied case is 16 kW. Sensitivity analysis showed the required power for different temperature settings (12-18ºC) and the effect of wind speed by analyzing the heat transfer coefficient of the cover, which doubled the power when the heat transfer coefficient increased from 4 to 10 W/m2.K.

CFD analysis of the impact of air gap width on Trombe wall performance

AbstractIn recent years, there has been a lot of research and debate on how solar energy can be used instead of conventional sources of heating to power residential heating. In this study, the Trombe wall (TW) technique, based on natural convection and energy storage, was examined to predict mass flow rate, temperature field, and velocity field for the TW system under steady conditions. A numerical simulation model was investigated for further validation using k‐ε turbulence and discrete ordinates (DO) radiation models. Independent grid studies were conducted to ensure that there were no changes after varying the grid numbers. The effect of the air gap was carried out to enhance TW thermal performance. CFD simulation shows good agreement with published data in the literature, and the optimum air gap was set at 0.1 m. The results pave the way for future studies to improve passive solar heating systems, which will eventually help move towards more sustainable residential heating solutions.

Shallow geothermal energy systems for district heating and cooling networks: Review and technological progression through case studies

Heating and Cooling constitute a major part of society's final energy use and a significant contributor to greenhouse gas emissions. The world society ought to mitigate climate change through decarbonisation, which must include the transition to low-temperature, sustainable and renewable heating and cooling technologies. Shallow Geothermal Energy is one of the most energy efficient and least greenhouse gas emitting available alternatives to provide space heating and cooling. The decarbonisation of the heating and cooling sector may have to comprise both individual systems and shared electrified heating and cooling systems from renewable sources of energy, where economies of scale and synergies between different types of consumers can be exploited. To this end, the focus of this paper is on the integration of shallow geothermal energy technologies into district heating and cooling systems. A key contribution of this work is the illustration of a number of practical case studies, highlighting the potential of existing shallow geothermal systems for DHC networks, which, as front runners in adopting such technologies, serve as paradigms for future development. Follows a discussion providing an outlook over the next 25 years. All in all, the future of utilizing shallow geothermal energy for district heating and cooling seems to be promising to play a pivotal role in sustainable urban development and decarbonizing the heating and cooling sector.

Sustainable Heat Generation in Flow from a Molecular Solar Thermal Energy Storage System

As the global deployment of renewable technologies accelerate, finding efficient ways to store energy will aid in responding to shifting energy demands. A prospective option not only in harvesting solar energy but also in emission‐free heating is MOlecular Solar Thermal (MOST) energy storage. A central part of MOST applications is to develop methods to release the stored energy. Herein, the Quadricyclane (QC)‐to‐Norbornadiene catalyzed back reaction is explored in a specially designed packed‐bed reactor. Four distinctly sized and purposely synthesized platinum on activated carbon catalysts are studied to trigger the heat release from the energy‐dense QC isomer. The catalysts are fully characterized using a variety of structural, surface, and spectroscopic techniques. Parameters to optimize catalytic conversion and heat release in flow conditions are explored including particle size and packing behavior, flow rates, and molecular residence times. Moreover, using CO pulse chemisorption technique, site time yield values and a turnover number are reported. Complementary to the flow reactions, computational fluid dynamic simulations applying lattice Boltzmann methods to two catalytic packed beds of different size ranges are done to evaluate fluid‐dynamic behavior within the reactor bed to ascertain the ideal particle size and packing density for catalysis in MOST applications.

A comparative analysis of policies and strategies supporting district heating expansion and decarbonisation in Denmark, Sweden, the Netherlands and the United Kingdom – Lessons for slow adopters of district heating

This paper undertakes a comprehensive comparative analysis of policy challenges and opportunities for the deployment of low-carbon DH. Through literature review and complementary qualitative analysis of interviews with key institutional stakeholders in the heating sector (n= 20) of Denmark, Sweden, the Netherlands, and the UK, the paper draws some important lessons on preconditions for successful roll-out of DH. We find that more governments must create appropriate conditions, provide more support, and speed up actions to enhance the role of DH in heat decarbonisation, to educate, encourage the adoption, and involve citizens, politicians, and other key stakeholders in the heat transition to DH. Amid the current energy price crisis, slow adopters must act fast to develop low-carbon DH networks to ensure the supply of secure, sustainable, and affordable heating sources. They would have to create appropriate conditions to reduce fossil-fuel path dependence, lock-out fossil fuel-based infrastructure and lock-in the diffusion and adoption of low-carbon DH.

Synthesis of Ti3C2Tx MXene@Carbon-Enhanced cellulose fiber composite-based photothermal absorber for sustainable water desalination

Desalination is a process that extracts salt and minerals from seawater to produce fresh water. It is critical, particularly for those who live on islands or coastal areas. Solar thermal desalination harnesses solar energy to address some of the challenges of traditional desalination methods. It uses solar power to heat seawater directly, initiating evaporation and leaving the salt behind, and further the vapor is condensed to produce fresh water. This method reduces reliance on fossil fuels, minimizing environmental impact and energy costs. This research unveils the synthesis of a solar evaporator consisting of Ti3C2Tx MXene coated over the carbon-enhanced cellulose fibers (CCF) (hereby termed the Ti3C2Tx MXene@CCF composite), which is the first-time report in the field of solar water desalination in using sustainable solar heat absorber. The Ti3C2Tx MXene@CCF composite achieves an impressive evaporation rate of 3.8 kg m−2 h−1 under 1 sun exposure. The hydrophilic Ti3C2Tx MXene coating on the porous CCF promotes rapid water evaporation. Ti3C2Tx MXene@CCF composite maximizes evaporation rates while maintaining water purity, which is in accordance with the World Health OrganizationFF (WHO) standards.

An innovative sustainable multi-generation energy system (electricity, heat, cold, and potable water) based on green hydrogen-fueled engine and dryer

Increasing renewables' portion in energy matrix around the world has made the scientists to propose innovative techniques for recovering the available waste heat of energy systems to produce excess energies in the Waste-to-X framework. This study proposes a green sustainable multi-generation energy system (MES), producing power, heat, cold, and potable water, driven by a hydrogen-fueled gas engine. The engine's heating potential is recovered to run some bottoming systems comprising proton exchange membrane electrolyzer (PEME), absorption/electrical chiller cycles (ACC/ECC), organic Rankine cycle (ORC), dryer unit, heat pump cycle (HPC), and reverse osmosis desalination unit. The combination of ACC with dryer and HPC is an innovative idea which utilized to produce heating load in this study. A detailed sustainability evaluation framework (technical and eco-environment) is derived to approve performance of the MES. The construction feasibility of the MES in different climatic conditions is sought by considering 5 case study cities around the world. Afterwards, best working fluid of the ECC/HPC and ORC is selected and then the sensitivity of the MES performance to design variables is investigated trough a comprehensive parametric study. Results illustrated that the MES shows the best performance in the city of Willington in which the emission of 84.8 tons of CO2 is prevented annually which is equivalent to saving of 16,291.6 m3 natural gas. The working fluid selection outputs proved that considering R22 and R123 for ECC/HPC and ORC leads the best techno-economic performance. The sensitivity study demonstrated that the highest and lowest influence of the MES's techno-economic performance is related to the ECC evaporator and ORC turbine temperatures, respectively. So that, increasing ECC evaporator temperature led to a relative variation of 8.2%, 4.5%, and 7.5% in energy recovery factor, exergy efficiency, and levelized cost of productions, respectively.

Microwave-induced plasma optical emission spectrometry (MIP-OES) analysis of the major elements in woody biomass ash following microwave acid digestion

The increasing use of woody biomass for sustainable heat and power is generating large amounts of woody biomass ash (WBA), which needs to be safely disposed of or recycled. In this study, the utility of Microwave-induced plasma optical emission spectrometry (MIP-OES) with microwave-assisted acid digestion for simplifying analyses of the major elements of WBA was investigated. Calibration curves exhibited good linearity (R2 > 0.999). Internal standardization using three emissions lines (324.754 nm of Cu, 451.131 nm of In and 371.029 nm of Y) showed that calibration with Cu (324.754 nm) correction resulted in the best linearity. Physical effects, even the presence of hydrofluoric acid or boric acid in mixed acids used for digestion, were of trivial influence with internal standard recoveries were within 0.95 to 1.05 times those of the blank sample. The limit of detection of MIP-OES for seven measured elements was 0.85–89 μg/L, 0.23–2.8 times higher than that of inductively coupled plasma optical emission spectrometry (ICP-OES). The recovery of elements in a certified fly ash reference material as determined by MIP-OES was 0.80–1.08. Elemental quantification of WBA samples by MIP-OES showed a strong correlation with that by ICP-OES. However, in a Welch's t-test, the MIP-OES values were significantly higher for K and significantly lower for Al and Ca in a majority of the samples. Nonetheless, considering the good correlation between their results, MIP-OES can replace ICP-OES for the analysis of WBA.

Understanding the thermodynamic effects of chemically reactive working fluids in the Stirling heat pump

Within the realm of sustainable heating technologies, this study examines the performance of a Stirling heat pump employing chemically reactive working fluids in contrast to conventional inert counterparts. Reactive working fluids are energy vectors that enable the conversion of not only thermal but also chemical energy within the heat pump. The investigation spans a wide range of theoretical reactive gaseous mixtures, leveraging the ideal gas mixture thermodynamic model. Each fluid is characterized by an equilibrated chemical reaction, denoted as A2(g)⇄2A(g), and distinguished by a set of reaction coordinates: the standard entropy change of reaction and standard enthalpy change of reaction. The chemical reaction evolution and thermodynamic properties are observed in each transformation, and the overall coefficient of performance (COP) of the system is evaluated and benchmarked against that of comparable inert working fluids. It is observed that the exothermic reaction during isothermal compression significantly increases the thermal energy supplied to the heat sink, as well as the thermal energy density per unit maximum volume, by up to 269 %, compared to an inert gas system. However, for the majority of reactive fluids studied, chemical reactions introduce irreversibility in the internal regenerator due to heat transfer across a finite temperature difference, contrary to the case of inert working fluids, penalizing the COP. Consequently, a reduction of up to 28 % in the COP is observed. Nevertheless, there exists a range of reactive fluids, characterized by reversible heat exchange in the internal regenerator, offering increased thermal energy transfer to the heat sink without compromising the COP.