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Electrification of homes is a critical part of reducing greenhouse gas (GHG) emissions. However, space constraints, installation complexity, and the potential impact on energy costs slows the pace of retrofit electrification efforts. Also, the addition of electrical circuits for heat pumps and the increased household electrical demand often necessitates electrical panel upgrades, which increases costs and slows installation. Multi-Function Heat Pumps (MFHPs) use a single compressor to provide heating, cooling, and domestic hot water (DHW) –which represent the most intensive thermal loads of a home –and can ease the process of retrofit electrification. MFHPs are potentially more economical than typical split HVAC heat pumps (HPs) and heat pump water heaters(HPWHs), as they consolidate systems, require fewer circuits, streamline installation, and enable efficiency opportunities, such as recovering waste heat from cooling to heat DHW. The current study evaluates one MFHP product, a split HP with indirect water heater and ducted air handler, using a low-global warming potential (GWP) refrigerant (R454B). This MFHP has a unique defrost operation that pulls heat from the DHW tank instead of the indoor air, which avoids cold drafts on occupants. This allows for better thermal comfort without requiring an electrical resistance backup heater and costly panel upgrades. The MFHP was installed in two low-income apartments, evaluated for ease of installation, and monitored through the heating season to assess reliability, energy efficiency, and performance.

In the transition from fossil fuel to electrified heating, a concerning trend is emerging in certain regions of the US. Owners of buildings with gas-based systems leave them in place after adding heat pumps (HPs). Existing control solutions for these hybrid (dual fuel) systems are rudimentary and fall short of realizing the full carbon reduction potential of these systems. Model predictive control (MPC) is often regarded as the benchmark for achieving optimal control in integrated systems. However, in the case of small-medium commercial buildings (SMCBs), the control and communication infrastructure required to facilitate the implementation of such advanced controls is often lacking. This paper presents a field implementation of easy-to-deploy MPC for a dual fuel heating system consisting of HPs and a gas-fired furnace (GF) for SMCBs. The control system is deployed on an open-source middleware platform and utilizes low-cost sensor devices to be used for real SMCBs without major retrofits. We demonstrated this MPC in a real office building with 5 HPs and 1 GF for 2 months. The test results showed that MPC reduced 27% of cost while completely eliminating GF usage by shifting 23% of the thermal load from occupied-peak time to non-occupied-non-peak times.

The increase in extreme weather conditions and greater penetration of intermittent renewable energy, such as solar and wind,have resulted in electric grid balancing challenges, and greenhouse gas emissions remain high during peak hours. Residentialload flexibility programs help mitigate these challenges by shaping the electricity demand of major appliances to better matchgrid-level renewable electricity generation profiles. This study evaluates the load flexibility of a multi-function heat pump(MFHP) system responding to a dynamic price signal. The residential MFHP uses a single air-source heat pump outdoor unitto efficiently meet both water heating and space conditioning needs. The MFHP does not require electric resistance heatersfor emergency heat or defrost, potentially avoiding the need for electrical panel upgrades commonly required when replacinggas appliances. A 14 kW (48 kBtu/h) MFHP system is installed in an occupied residential building in California. To achieveload flexibility, a rule-based control algorithm adjusts water heating and space cooling setpoints with the objective ofminimizing electric energy cost in response to the dynamic price signal. Model-based control approaches require training dataand forecasting, increasing the complexity and commissioning time. The simplicity of this rule-based control approach will beeasier to adopt for widescale use because it has lower computational complexity, works with equipment from differentmanufacturers, and does not require in-depth programming and commissioning. The dynamic price signal used by thealgorithm consists of a forecast of hourly prices for the next 24-hour period. The rule-based algorithm determines hourlysetpoint schedules for the next 24-hour period based on the dynamic price signal for the water heating and space conditioningand communicates them to the MFHP thermostats.

Introducing Energy hubs (EHs) is a beneficial strategy for incorporating quickly expanding renewable energies. However, the stochastic nature of renewable energy sources (RESs) and fluctuating energy demand have produced a number of difficulties, including unstable voltage/frequency, challenging energy management, and difficult network interaction. Additionally, the changing in response time of electrical and heat demands will make control challenging. This paper proposes a distributed control system for use with dynamic EHs. The RESs and loads present in the multi-carrier system cause the dynamics considering here. In order to optimise system performance, this research suggests a distributed model predictive control strategy that considers expected behaviour and operational restrictions. The strategy's potential is demonstrated via simulations in which the proposed scheme is applied to a benchmark system. [ABSTRACT FROM AUTHOR]

The article describes design of a solar dryer with a heat pump, which is used to increase heat output of the unit twice to solve the problem of using environmentally clean sources of thermal energy for fruit drying. The authors of the research have developed methodology of substantiation of the solar dryer parameters, which is applied to design and justify the optimal technological modes and parameters of the heat carrier in the unit, to describe the heat transfer characteristics of the unit operation, to assess the impact of physical environmental parameters on technological indicators of the process. The novelty described in the article is developed design of a solar dryer with a heat pump and to substantiate its constructive and technological structure. The work supplies scientifically substantiated methodic recommendations on composing and forecasting a parametric series of solar dryers for the conditions of private households and farms, and grounds their design parameters. Designed solar dryer with a heat pump affects solving environmental problems of power engineering due to substitution of the electric and thermal energy by the one obtained from solar energy, and mitigation of social problems by creating new job places needed when producing, installing and exploiting such units. The obtained results can be used for designing and improving technical aspects of fruit drying, to increase technological and energy efficiency of the process. [ABSTRACT FROM AUTHOR]

According to extant Italian legislation implementing the Renewable Energy Directive, the mandatory renewable quota for a new building is 60% referring to a single service (e.g., heating during winter) or to multiple services (e.g., heating during winter and air conditioning during summer), depending on which services are actually present. The obligation to satisfy this minimum value often leads heating and ventilation plant designers to provide heat pump systems in industrial buildings, typically air/water or direct expansion type coupled with air terminals (air heaters or ventilation units) or radiant floors. The question is: Is this always the most advantageous option for industrial buildings? A typical industrial building was modeled by Trnsys® in two different climates. Based on the calculated thermal heating loads, the condensing radiant tubes and heat pump coupled with the air heaters systems were analyzed through dynamic simulation, evaluating their performance from an energy, environmental impact, and economic point of view. The analysis carried out revealed that a heat pump system is not always the most advantageous solution depending on the climate, the characteristics of the building (less or more thermal insulation, which corresponds to existing buildings rather than new ones), and the size of the photovoltaics system eventually installed on the roof. [ABSTRACT FROM AUTHOR]

To achieve the goals of carbon peaking and carbon neutrality, the retrofitting of existing coal-fired power plants is crucial to achieving energy-saving and emission reduction goals. A conventional recovery system of waste heat typically occurs downstream of the air preheater, where the energy quality in flue gas is low, resulting in limited coal-saving benefits. This study proposes a scheme involving a flue gas exchanger bypassing the air preheater and low-temperature economizers, which is used to transfer the waste heat from flue gas to primary and secondary air (System I). Additionally, a heat pump can be introduced to provide supplementary energy for primary and secondary air, as well as the condensate from the steam turbine (System II). The coal consumption rate and exergy efficiency are used to evaluate the two schemes. The results show that both waste heat recovery systems can increase the power output of the coal-fired unit by recovering waste heat. System II can boost power output by approximately 13.98 MW. The power increase in both waste heat recovery systems show a declining trend as the unit load decreases. This increased power is primarily attributed to the medium- and low-pressure cylinders, while the contributions from ultra-high-pressure and high-pressure cylinders are negligible. The increased power output for the medium-pressure cylinder ranges from approximately 3.49 to 3.58 MW, while the low-pressure cylinder has an increased power output of around 10.10 to 10.19 MW. The coal consumption rate is decreased from 250.3 g/(kW·h) to 247.5 g/(kW·h) under a full load condition for both systems, which can be augmented at lower load conditions. System II outperforms System I at 30% load condition, achieving a reduced coal consumption rate of 3.36 g/(kW·h). System I has an exergy efficiency of 40%, while System II shows a higher efficiency of 44%. [ABSTRACT FROM AUTHOR]

Large scale heat pumps (LSHP) have seen a rapid proliferation in recent years, with projects and initiatives aimed at integrating electrically driven LSHP into existing district heating networks (DHN). The financial advantages have driven most LSHP installations to be powered by electricity generated by on-site cogeneration (CHP), given CHP's dominant role in DHN. This LSHP + CHP combination poses the question, to what extent ecological improvements, measured as a reduction in specific CO2 emissions through LSHP operation can be achieved, contingent on the source of electricity and heat source employed. In this paper, the LSHP + CHP combination was generally analysed under usage of exergy analysis and a 2nd law derived method is presented. This method allows to evaluate the magnitude of CO2 reduction through LSHP operation across all common heat sources in 1st to 4th generation DHNs in conjunction with CHP. Results show, that in LSHP + CHP combination, heat from LSHP using either of the 2 heat sources ambient air or surfaced water, inevitably comes with higher specific CO2 emissions over the CHP heat. Only when using a sufficiently hot and emissions-free heat source, the LSHP heat from a LSHP + CHP combination can yield to an annual best case of half the CO2 emissions of the CHP. Importantly, the choice of power source has a far more significant impact, as LSHP powered by electricity from renewable energy sources achieve more than an eight-fold reduction in emissions compared to the LSHP + CHP combination. Therefore, power consumption with sufficiently low specific CO2 emissions out of external source is imperative to fully realize the ecological benefit of LSHP in DHN, underlining that the successful heat transition through LSHP relies heavily on the transformation of the electricity supply. Highlights: Based on the 2nd law a methodology is derived around exergy analysis, that enables a universal assessment of the ecological benefit of LSHP powered by CHP (Chapter 3). Graphs to determine every possible combination are presented (Chapter 4). Results are drawn for the most common CHP & LSHP including the most common types of heat source to grasp the scope of the discussed problematic. Ecological impact of LSHP in DHN are shown for comparison for most common types of CHP and LSHP- heat sources. [ABSTRACT FROM AUTHOR]

Methods and instrumentation for measuring grout quality in heat pump boreholes, including the measurement of groundwater flow through boreholes outside partly grouted borehole exchanger pipes, have been developed in the Czech Republic. A Semtex charge has also been developed to repair rock massifs, which reliably disconnects borehole exchanger pipes without severely harming the surrounding rock environment or buildings. The resulting hole can then be used for regrouting, thus preventing undesirable vertical water flow through the borehole. [ABSTRACT FROM AUTHOR]

Water scarcity is a major issue in cities situated at the Caspian regions of Kazakhstan. To overcome this issue, two compression heat pump-assisted solar thermal desalination configurations are proposed in this research. A numerical model using the TRNSYS simulation package was developed to predict the energy performance of the proposed systems and was validated with experimental results available in the open literature. The influence of ambient parameters and water depth in the basin of a solar still and insulation thickness was analyzed. The performance of proposed configurations is compared with conventional solar still. The errors noticed at 2 and 10 cm depths are 23.6% and 12.1%, respectively. The simulation results confirmed that the heat pump-assisted regenerative solar still configuration has a 91.1%, 73.0%, 61.6% and 82.6% improved productivity during winter, spring, summer and autumn climates, respectively. The results confirmed that significant improvement in freshwater production was observed with heat regeneration compared to the configuration without heat regeneration. The maximum freshwater production with heat regeneration reached 18.0 kg m−2 day−1 in summer and 9.0 kg m−2 day−1 in winter. The optimal water depth in the basin is observed to be in the range between 0.5 and 2.0 cm, while the insulation thickness is between 5.0 and 7.0 cm. The results confirmed that the proposed configuration satisfies the water requirements in Kazakhstan. [ABSTRACT FROM AUTHOR]

Integration of heat pumps combined with thermal energy storage provides a key pathway to decarbonizing the energy supply in the industry when the processes are not operated continuously. Yet, this integration of such novel systems introduces control challenges due to added dependencies between different process streams. This work investigates the control problem of heat pumps coupled to stratified thermal energy storage that is integrated into non-continuous industrial processes. A two-layer control strategy is proposed, where, in the higher level, a model predictive controller is developed for energy management using a linear model of the non-linear process. The resulting optimization problem is a mixed integer quadratic program. The low-level control layer is defined with standard industry controllers. The overall system is tested using a dynamic simulation model for the entire process, demonstrating its performance in three different cases. The control strategy optimizes heat recovery while ensuring system operability. The study demonstrates successful disturbance rejection and cold starts, wherein 100% of the targeted heat recovery can be confirmed under nominal conditions. Further evaluation in laboratory or field trials is recommended, and alternative, yet-to-be-defined, control concepts may be compared to the proposed approach. [ABSTRACT FROM AUTHOR]

• A novel parameter is introduced to refine the refrigerant leakage theory. • The refrigerant leakage process carries a higher oil content is confirmed. • The effect of leakage mass flow rate on oil content is investigated. • The oil content is highest when refrigerant leaks from the high-pressure pipe. Refrigerant leakage is a situation that often occurs in refrigeration equipment such as heat pumps. However, certain alternative refrigerants, while exhibiting superior environmental performance, possess varying levels of flammability. The leakage of flammable refrigerants into confined spaces can pose a significant risk of explosion. The amount of lubricant in the leaking refrigerant will undoubtedly affect the flammability characteristics of the refrigerant. In this paper, the content of PVE32 oil in the leaking refrigerant during the operation of a heat pump was investigated. The results showed that, under the five leakage rate scenarios set up in the experiment, the oil concentration was highest when the leakage occurred at the condenser inlet and lowest when the leakage was at the evaporator outlet. During the leakage process of the experiment, as the mass flow rate of the leakage increased, the oil content in the early stage of the leakage increased, but the oil content in the late stage of the leakage decreased. The reasons for the change in oil content were analyzed by the oil circulation rate and the degree of phase separation. The decrease of the oil circulation rate and the change of the degree of phase separation were the key factors affecting the magnitude of the oil content as the leakage proceeded. The results of the study reveal the leakage characteristics of lubricating oil with refrigerant leakage. [ABSTRACT FROM AUTHOR]

Data centers (DCs) are highly energy-intensive facilities, where about 30%–50% of the power consumed is attributable to the cooling of information technology equipment. This makes liquid cooling, especially in two-phase mode, as an alternative to air cooling for the microprocessors in servers of interest. The need to meet the increased power density of server racks in high-performance DCs, along with the push towards lower global warming potential (GWP) refrigerants due to environmental concerns, has motivated research on the selection of two-phase heat transfer fluids for cooling servers while simultaneously recovering waste heat. With this regard, a heat pump-assisted absorption chiller (HPAAC) system for recovering waste heat in DCs with an on-chip two-phase cooling loop driven by the compressor is proposed in the present paper and the low GWP hydrofluoroolefin refrigerants, including R1224yd(Z), R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R1243zf and R1336mzz(Z), are evaluated and compared against R245fa as server coolant. For the HPAAC system, beginning with the development of energy and economic models, the performance is analyzed through both a parametric study and optimization using the coefficient of performance (COP), energy saving ratio (ESR), payback period (PBP) and net present value (NPV) as thermo-economic indicators. Using a standard vapor compression cooling system as a benchmark, the results indicate that with the evaporation temperature between 50°C and 70°C and the subcooling degree ranging from 5°C to 15°C, R1233zd(E) with moderate compressor suction pressure and pressure ratio is the best refrigerant for the HPAAC system while R1234yf performs the worst. More importantly, R1233zd(E) is also superior to R245fa based on thermo-economic performance, especially under work conditions with relatively lower evaporation temperature as well as subcooling degree. Under the given working conditions, the overall COP, ESR, NPV, and PBP of R1233zd(E) HPAAC with optimum subcooling degree range from 4.99 to 11.27, 25.53 to 64.59, 1.13 to 4.10 × 107 CNY and 5.77 to 2.22 years, respectively. Besides, the thermo-economic performance of R1233zd(E) HPAAC under optimum working conditions in terms of subcooling degree varying with the evaporation temperature is also investigated. [ABSTRACT FROM AUTHOR]

This study proposes a novel onboard carbon capture system (OCCS) with reduced fuel consumption. The proposed system included a heat pump with an intermediate heat exchanger, a parallel compressor, and a steam compressor. The proposed system consumed 43% less fuel than the boiler for producing the same amount of steam, which was required for CO2 stripping. In addition, a blended solvent of amino methyl propanol (AMP) and piperazine (PZ) was applied to the OCCS. A rate-based process simulation indicated that this solvent resulted in 22% lower reboiler duty, compared to a monoethanolamine (MEA) solvent. Further, it was shown that the proposed OCCS with the heat pump and the AMP/PZ solvent achieved a reduction of approximately 50% in both fuel consumption and CO2 emissions along with 26.9 USD reduction for capturing one ton of CO2, compared to the OCCS with a boiler and MEA solvent. [ABSTRACT FROM AUTHOR]

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The integration of renewable energy sources (RESs) is rapidly increasing within energy systems worldwide. However, this shift introduces intermittency and uncertainty on the supply side. To hedge against RES intermittency, demand-side flexibility introduces a practical solution. Therefore, further studies are required to unleash demand-side flexibility in power systems. This flexibility is relevant across various sectors of power systems, including residential, industrial, commercial, and agricultural sectors. This paper reviews the key aspects of demand-side flexibility within the residential sector. To achieve this objective, a general introduction to demand flexibility across the four sectors is provided. As a contribution of this paper, and in comparison with previous studies, household appliances are classified based on their flexibility and controllability. The flexibility potential of key residential demands, including heat pumps, district heating, electric vehicles, and battery systems, is then reviewed. Another contribution of this paper is the exploration of demand-side flexibility scheduling under uncertainty, examining three approaches: stochastic programming, robust optimization, and information-gap decision theory. Additionally, the integration of demand flexibility into short-term electricity markets with high-RES penetration is discussed. Finally, the key objective functions and simulation software used in the study of demand-side flexibility are reviewed. [ABSTRACT FROM AUTHOR]

This paper presents the results of the technical validation of an innovative prototype for drying alfalfa bales. It is based on a 4.1 kW Heat Pump (HP) that uses an advanced technology (optimized for extracting the humidity from the air) and is directly powered by a 6.6 kWp PV generator without grid or batteries support. The main technical challenges of this work were managing solar irradiance fluctuations due to cloud-passing and achieving good drying efficiency. The prototype has been validated for two consecutive drying campaigns in La Rioja (Spain). There were no abrupt stops generated by cloud-passing. The PRPV, which evaluates the performance of the PV system only during the periods when the PV energy can be used by the HP unit, presented values of 0.82 and 0.85, comparable to a well-performing grid-connected PV system. Although the bales' initial relative humidity (RH) ranged from 18 to 30%, all but one of them presented a final RH below 16%, which is the limit point to avoid fermentation. The drying times ranged from 1 to 5 h, and the specific energy consumption per liter of water extracted, from 0.7 to 1.46 kWh/L. These values are comparable to traditional diesel and grid-powered systems. It is worth noting that the agricultural drying market represented USD 1.7 billion in 2023. [ABSTRACT FROM AUTHOR]

Efficient and reliable utilization of renewable energy at the user's end is the key to achieving a low‐carbon life. This paper proposed a new distributed energy system around the comprehensive utilization of solar energy by integrating solid oxide fuel cell (SOFC), energy storage equipment, photovoltaic thermal (PVT) collector, and heat pump. By integrating the use of SOFC and PVT, we can further minimize reliance on fossil fuels, while employing the coupling of PVT and heat pump effectively mitigates the inherent challenges of solar energy's variability and intermittency, all while enhancing overall system efficiency. On this basis, we apply the heat current method to construct a cross‐scale heat current model of the components and the system by considering the energy transfer, conversion, and storage characteristics of the system. By employing this model, we simulate the system's operation throughout an entire typical day, assess the COP enhancement of the PVT‐coupled heat pump system, analyze the influence of diverse operating conditions on daily system performance, and evaluate the economy of the energy storage devices in the system. [ABSTRACT FROM AUTHOR]

Peltier cells are commonly used in low-power cooling applications, such as automotive refrigerators and electronics temperature regulation systems. These applications are typically low-energy in nature. There is currently a growing emphasis on energy conservation and waste heat utilization in the energy industry. This paper explores the possibility of improving the heating or cooling coefficient of performance (COP) of Peltier cells through intelligent serial and parallel connections. The purpose of this work is to raise the question of whether it would be possible to reconsider the concept of harnessing the "energy" potential of Peltier cells. The utilized model is in line with the current state of the art, and the case study is based on parameters measured on a commercially available Peltier cell. The resulting COP, when considering current materials, remains inferior to the COP of compressor-based heat pumps. For low-power devices, it can represent a technically and economically comparable solution. [ABSTRACT FROM AUTHOR]

This paper presents a comparative analysis of a finned heat exchanger fed with synthetic refrigerant R410a and environmentally friendly refrigerant R290. Analyses of the performance of the heat exchanger operating as an evaporator in a refrigeration system were carried out. Simulation studies were performed using SOLIDWORKS software with the Flow Simulation library. The analysis was conducted for various design parameters of the device. The performance of the exchanger was examined for different fin materials (aluminium alloys: alloy 1060, 1060-H12, alloy 2014, alloy 2024), number of fins (78 and 39), and fin spacings (2.5 mm and 5 mm). The studies were conducted under various operational parameters of the exchanger (varying volume flow of air and refrigerant mass flow). Based on the results obtained, it was found that the material of the exchanger does not significantly affect its performance. The next conclusion is that when the heat exchanger is fed with an environmentally friendly refrigerant, the heat transfer surface area can be reduced by 50%. As a result, the reduction in heat transfer surface area can be achieved by increasing the fin spacing, which will reduce the electricity consumed in the defrost process under operating conditions, or by reducing the size of the exchanger, which will positively translate into a reduction in the weight of the refrigerant in the system. The possibility of reducing the dimensions of the heat exchanger by up to 50% indicates that replacing R410a refrigerant with environmentally friendly R290 is a promising direction for development. It advocates for ongoing investigations to refine these systems and maximize the operational advantages presented by natural refrigerants. [ABSTRACT FROM AUTHOR]

The present work represents a continuation of our research in the field of evaluating the thermal efficiency (coefficient of performance) of a heat pump, research started and published in 2019 [1]. In the previous work it was considered the refrigerating machine, this time we will refer exclusively to the mechanical vapor compression heat pump. The evaluation of the COP for a heat pump is absolutely mandatory in the calculation procedure of contribution of the renewable resources of energy, offered by the implementation of a heat pump in the thermal utility supply systems in buildings (space heating and/or hot water preparation). [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Industrial buildings have numerous kinds of energy-losing equipment, such as engines, ovens, boilers and heat exchangers. Energy losses are related to inefficient energy use and lousy work conditions for the people inside the buildings. This work is devoted to the recovery of lost energy from industrial buildings. Firstly, the residual energy of the building is extracted to be used to warm water. Consequently, the work conditions of the people inside industrial buildings can be improved by maintaining the adequate temperature. The recovery of the energy is performed by a multipurpose heat pump system (HP system). The working fluid used in the HP system is R134a, which is a traditional and cheap working fluid. The thermophysical properties of R134a are obtained through the PC-SAFT equation of state. This work presents a performance mapping based on the intercepted areas framework to evaluate which working conditions are the optimal operating variables. The latter depends on several key parameters, such as compressor work, heat delivery, heat absorbed and exergetic efficiency. The results show that the optimal work conditions are found at different condenser and evaporator temperatures, and these may be limited by what the designer considers a sound performance of the heat pump system. [ABSTRACT FROM AUTHOR]

Ventilation, cooling, heating, and air conditioning (HVAC) systems represent a substantial portion, approximately 40%, of energy consumption in buildings. Among the key components of HVAC/R systems, the compressor, fans, and electrical resistances are major consumers of electricity. In this context, the compressor stands out due to its significant dynamic behaviour, serving as the pivotal element in heat pump operations. However, many manufacturers solely provide empirical data regarding compressor performance, lacking comprehensive models for assessing performance across various operational conditions. This paper addresses the methodology for evaluating mathematical models utilizing experimental compressor data. Through this approach, we aim to bridge the gap between empirical observations and predictive modelling, enabling a more nuanced understanding and optimization of HVAC/R system performance. The proposed model uses interpolation and it takes as input the evaporation and condensation temperatures. It shows an R -- square and adjusted R -- square value of 0.99. By using the experimental data and an open -- source library for interpolation this paper paves the way for a flexible and practical compressor modelling. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rapid expansion of renewable energy in buildings has been expedited by technological advancements and government policies. However, including highly permeable intermittent renewables and energy storage presents significant challenges for traditional home energy management systems (HEMSs). Deep reinforcement learning (DRL) is regarded as the most efficient approach for tackling these problems because of its robust nonlinear fitting capacity and capability to operate without a predefined model. This paper presents a DRL control method intended to lower energy expenses and elevate renewable energy usage by optimizing the actions of the battery and heat pump in HEMS. We propose four DRL algorithms and thoroughly assess their performance. In pursuit of this objective, we also devise a new reward function for multi-objective optimization and an interactive environment grounded in expert experience. The results demonstrate that the TD3 algorithm excels in cost savings and PV self-consumption. Compared to the baseline model, the TD3 model achieved a 13.79% reduction in operating costs and a 5.07% increase in PV self-consumption. Additionally, we explored the impact of the feed-in tariff (FiT) on TD3's performance, revealing its resilience even when the FiT decreases. This comparison provides insights into algorithm selection for specific applications, promoting the development of DRL-driven energy management solutions. [ABSTRACT FROM AUTHOR]

Energy efficiency improvement in Chinese construction has progressed rapidly over the past two decades. Nearly zero energy buildings (NZEBs), as an integrated solution for energy-efficient construction, have gained significant attention during China's 13th Five-Year Plan period, with continuous maturation of the technical system. In this study, a research framework built upon the accomplishments of China's National Key Research and Development Program is developed, and an in-depth analysis of the most cutting-edge research is provided by thoroughly reviewing the work conducted earlier. Developing NZEB in China has been categorized into three stages based on the characteristics of technological development: (1) definition and standards, (2) demonstration and promotion, and (3) cross-domain integration. This study discerns four noteworthy development trends by examining comprehensive data spanning the last decade from 100 NZEB and zero energy building. Further, a comprehensive analysis of essential technology advancements in line with these identified trends is performed. The issues and challenges arising from the increased application of renewable energy in the context of China's carbon peak and carbon neutrality goals have also been discussed. Finally, based on this analysis, the challenges and corresponding suggestions for future research directions were proposed to help guide future studies exploring emerging trends in the NZEB field. [ABSTRACT FROM AUTHOR]

Heat pumps are recognized as a key tool in the energy transition toward a carbon-neutral society, enabling the electrification of the heating sector at least for low- and medium-temperature heat demands. In recent years, natural refrigerants have been reconsidered due to their low environmental impact: among them, CO2 is a safe option without an impact on the ozone layer and low global warming potential compared to synthetic fluids. However, as a consequence of its thermophysical properties, its thermodynamic cycle is transcritical and is particularly suitable for specific end-user temperature profiles. This paper analyzes in a systematic and thorough way the most significant modifications to the reference cycle that have been proposed in the literature to improve the performance, finding how the optimal configurations change with a change in the rated operating conditions (inlet temperature and temperature glide of the heat demand, and ambient temperature). Exergy analysis explains why there is an optimal gas cooler pressure and why its trend with the average temperature is split into two distinct regions, clearly recognizable in all cycle layouts. The maximum coefficient of performance (COP) of the reference cycle varies in the 1.52–3.74 range, with a second-law efficiency of 6.4–36.1%, for an optimal gas cooler pressure of up to 15.45 MPa, depending on the ambient temperature and end-user temperature profile. The most effective modification is the cycle with an ejector and internal heat exchanger, which raises the COP to 1.84–4.40 (second-law efficiency 8.7–45.56%). The presented results provide an extensive guide to understanding the behavior of a transcritical CO2 cycle and predict its performance in heat pump applications. [ABSTRACT FROM AUTHOR]

Abstract Introducing Energy hubs (EHs) is a beneficial strategy for incorporating quickly expanding renewable energies. However, the stochastic nature of renewable energy sources (RESs) and fluctuating energy demand have produced a number of difficulties, including unstable voltage/frequency, challenging energy management, and difficult network interaction. Additionally, the changing in response time of electrical and heat demands will make control challenging. This paper proposes a distributed control system for use with dynamic EHs. The RESs and loads present in the multi-carrier system cause the dynamics considering here. In order to optimise system performance, this research suggests a distributed model predictive control strategy that considers expected behaviour and operational restrictions. The strategy’s potential is demonstrated via simulations in which the proposed scheme is applied to a benchmark system.

The article describes design of a solar dryer with a heat pump, which is used to increase heat output of the unit twice to solve the problem of using environmentally clean sources of thermal energy for fruit drying. The authors of the research have developed methodology of substantiation of the solar dryer parameters, which is applied to design and justify the optimal technological modes and parameters of the heat carrier in the unit, to describe the heat transfer characteristics of the unit operation, to assess the impact of physical environmental parameters on technological indicators of the process. The novelty described in the article is developed design of a solar dryer with a heat pump and to substantiate its constructive and technological structure. The work supplies scientifically substantiated methodic recommendations on composing and forecasting a parametric series of solar dryers for the conditions of private households and farms, and grounds their design parameters. Designed solar dryer with a heat pump affects solving environmental problems of power engineering due to substitution of the electric and thermal energy by the one obtained from solar energy, and mitigation of social problems by creating new job places needed when producing, installing and exploiting such units. The obtained results can be used for designing and improving technical aspects of fruit drying, to increase technological and energy efficiency of the process.

Abstract Large scale heat pumps (LSHP) have seen a rapid proliferation in recent years, with projects and initiatives aimed at integrating electrically driven LSHP into existing district heating networks (DHN). The financial advantages have driven most LSHP installations to be powered by electricity generated by on-site cogeneration (CHP), given CHP’s dominant role in DHN. This LSHP + CHP combination poses the question, to what extent ecological improvements, measured as a reduction in specific CO2 emissions through LSHP operation can be achieved, contingent on the source of electricity and heat source employed. In this paper, the LSHP + CHP combination was generally analysed under usage of exergy analysis and a 2nd law derived method is presented. This method allows to evaluate the magnitude of CO2 reduction through LSHP operation across all common heat sources in 1st to 4th generation DHNs in conjunction with CHP. Results show, that in LSHP + CHP combination, heat from LSHP using either of the 2 heat sources ambient air or surfaced water, inevitably comes with higher specific CO2 emissions over the CHP heat. Only when using a sufficiently hot and emissions-free heat source, the LSHP heat from a LSHP + CHP combination can yield to an annual best case of half the CO2 emissions of the CHP. Importantly, the choice of power source has a far more significant impact, as LSHP powered by electricity from renewable energy sources achieve more than an eight-fold reduction in emissions compared to the LSHP + CHP combination. Therefore, power consumption with sufficiently low specific CO2 emissions out of external source is imperative to fully realize the ecological benefit of LSHP in DHN, underlining that the successful heat transition through LSHP relies heavily on the transformation of the electricity supply. Graphical Abstract

Objective. Over the past decades, heat pumps have gained great popularity due to their advantages in energy efficiency and environmental friendliness, becoming one of the most attractive alternatives to replace traditional heating systems running on fossil fuels. Heat pump efficiency is a decisive factor that should be taken into account when selecting and optimizing a heat pump system. The aim of the study was to evaluate the efficiency of air source heat pumps of the air-to-water system in the climatic conditions typical of the regions of the Central Federal District. Method. To evaluate the efficiency of air source heat pumps, a mathematical model is used that takes into account the multifactorial nature of the process under study. Result. To adequately compare the obtained research results with the passport performance indicators, the transformation coefficient (COP) was used, showing the ratio of the energy received to the expended work. As a result, the method of heating rooms with an air source heat pump with a combined operation mode was recognized as more preferable. Conclusion. Currently, the potential of heat pumps in the field of energy saving and CO2 emission reduction remains largely untapped, which sets the vector for further research.

Abstract Methods and instrumentation for measuring grout quality in heat pump boreholes, including the measurement of groundwater flow through boreholes outside partly grouted borehole exchanger pipes, have been developed in the Czech Republic. A Semtex charge has also been developed to repair rock massifs, which reliably disconnects borehole exchanger pipes without severely harming the surrounding rock environment or buildings. The resulting hole can then be used for regrouting, thus preventing undesirable vertical water flow through the borehole.

Abstract Efficient and reliable utilization of renewable energy at the user's end is the key to achieving a low‐carbon life. This paper proposed a new distributed energy system around the comprehensive utilization of solar energy by integrating solid oxide fuel cell (SOFC), energy storage equipment, photovoltaic thermal (PVT) collector, and heat pump. By integrating the use of SOFC and PVT, we can further minimize reliance on fossil fuels, while employing the coupling of PVT and heat pump effectively mitigates the inherent challenges of solar energy's variability and intermittency, all while enhancing overall system efficiency. On this basis, we apply the heat current method to construct a cross‐scale heat current model of the components and the system by considering the energy transfer, conversion, and storage characteristics of the system. By employing this model, we simulate the system's operation throughout an entire typical day, assess the COP enhancement of the PVT‐coupled heat pump system, analyze the influence of diverse operating conditions on daily system performance, and evaluate the economy of the energy storage devices in the system.

This paper presents a comparative analysis of a finned heat exchanger fed with synthetic refrigerant R410a and environmentally friendly refrigerant R290. Analyses of the performance of the heat exchanger operating as an evaporator in a refrigeration system were carried out. Simulation studies were performed using SOLIDWORKS software with the Flow Simulation library. The analysis was conducted for various design parameters of the device. The performance of the exchanger was examined for different fin materials (aluminium alloys: alloy 1060, 1060-H12, alloy 2014, alloy 2024), number of fins (78 and 39), and fin spacings (2.5 mm and 5 mm). The studies were conducted under various operational parameters of the exchanger (varying volume flow of air and refrigerant mass flow). Based on the results obtained, it was found that the material of the exchanger does not significantly affect its performance. The next conclusion is that when the heat exchanger is fed with an environmentally friendly refrigerant, the heat transfer surface area can be reduced by 50%. As a result, the reduction in heat transfer surface area can be achieved by increasing the fin spacing, which will reduce the electricity consumed in the defrost process under operating conditions, or by reducing the size of the exchanger, which will positively translate into a reduction in the weight of the refrigerant in the system. The possibility of reducing the dimensions of the heat exchanger by up to 50% indicates that replacing R410a refrigerant with environmentally friendly R290 is a promising direction for development. It advocates for ongoing investigations to refine these systems and maximize the operational advantages presented by natural refrigerants.

This paper presents an experimental investigation of the effects of a decreasing refrigerant charge on the performance and operating conditions of an R513A water-to-water heat pump equipped with a large liquid receiver, an electronic expansion valve, and a vapor accumulator at the compressor inlet. The mass of the refrigerant inside the machine is progressively extracted to simulate refrigerant leakages occurring during the normal operation or in case of failures. The results show that the subcooling is the parameter mostly affected by a refrigerant charge variation since it rapidly collapses to 0 K with the charge reduction. Furthermore, it is possible to identify three different zones in which almost all the properties analyzed (COP, heating capacity, operating pressures and expansion valve opening) exhibit peculiar trends with the charge decrease: subcooling sensitivity zone, constant parameters zone, and compressor failure risk zone. The extension of these zones is determined by the size of the liquid receiver which is installed in the system and, for the heat pump under consideration, is between 100% and 95% of the initial charge for the first zone, between 95% and 40% for the second zone, and below 40% for the third zone. [ABSTRACT FROM AUTHOR]

• Impact of refrigerant leakage on R513A when replacing R134a. • R513A has better stability in response to refrigerant leaks. • Refrigerant leakage affects both direct and indirect carbon emissions. • A 20 % leakage could increase indirect carbon emissions by 6.3 %. The escalating threat of global warming has highlighted the imperative to address the greenhouse effect. R513A is recognized as a viable substitute for R134a, providing a lower global warming potential (GWP) while preserving similar thermodynamic properties. However, refrigerant leakage is one of the common faults in heat pump equipment. For industrial heat pumps, refrigerant leakage can make the system less stable and affect normal industrial production, while long-term leakage can also affect the carbon emissions of the industry. When substituting refrigerants, it is crucial to consider not only their distinct properties under typical operating conditions but also the stability and environmental impact of the alternative refrigerant in cases of leakage. This paper focuses on experimentally evaluating the impact of using R513A to replace R134a on the performance of refrigeration systems under the condition of rapid refrigerant leakage. Then the life cycle climate performance evaluation (LCCP) theory is used to assist experimental results in evaluating the carbon footprints of R513A and R134a systems at different annual leakage rates. The results show that R513A has better stability than R134a when responding to rapid refrigerant leakage. This paper determines the changes in annual electricity consumption and indirect emissions under several annual leakage rates and finds that the impact of leakage on indirect emissions is also not negligible. During the utilization phase of the equipment, when leakage was taken into account, the carbon emissions of the R134a system were higher. [ABSTRACT FROM AUTHOR]

This paper presents a conventional air source heat pump cycle (CHPC) and two dual-temperature air source heat pump cycles (DTHPC1 and DTHPC2). DTHPC1 employs two condensers, while DTHPC2 adds an extra compressor and combines the ejectors on top of DTHPC1. Compared with the conventional heat pump cycle, the new dual-temperature heat pump DTHPC2 can provide hot water at one additional temperature and still have high performance. In this paper, the refrigerants R1234yf and R1234ze(E) were selected as suitable for the cycle conditions. The cycle performance under different conditions was simulated and compared based on energy analysis methods and exergy analysis methods. The main performance parameters included COP h , η ex , etc. The results demonstrate that the COP h and η ex of DTHPC2 and DTHPC1 are greater than those of CHPC under identical conditions. Specifically, at an ambient temperature of approximately -10 °C, high-temperature hot water of approximately 65 °C, and low-temperature hot water of approximately 35 °C, the COP h of DTHPC2 and DTHPC1 increased by 45% and 32.7%, respectively, in comparison to CHPC. Similarly, the η ex of DTHPC2 and DTHPC1 increased by 27.1% and 28.9%, respectively. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the operating characteristics of a chemisorption heat pump. 1-D transient model of a chemisorption heat pump was developed, for which an analysis of four alternating modes of operation was performed. The performance was analyzed with respect to the operating time of the adsorption and desorption operation modes during alternating operations, and the results showed that the cooling capacity has an optimum point depending on the operating times. It was also confirmed that the coefficient of performance increases as the operating time increases. The system performance was also analyzed according to the flow rates of the secondary fluids supplied to the main components. As the flow rates of the secondary fluids supplied to the main components increased, the cooling capacity improved, and the coefficient of performance was found to be compounded by the secondary flow conditions and the operating times of the adsorption and desorption operation modes. Based on the results, it was found that the cooling capacity, coefficient of performance, and specific cooling power of the chemisorption heat pump can be operated in a large range from 876.7 to 3070.0 W, 0.13 to 0.32, and 39.3 to 137.7 W/kg, respectively, depending on the operating conditions. [ABSTRACT FROM AUTHOR]

Purpose – This paper aims to propose a methodology for assessing an optimal portfolio of investment instruments that minimise the social costs of decarbonising economic activity while improving the environmental objectives proposed in EU legislation. Design/methodology/approach – The methodology defines the net social cost of decarbonisation related to a portfolio of four instruments: installation of solar PV and wind generation, thermal insulation of households and deployment of heat pumps. The social cost is minimised by restricting it to the minimum level of the targets proposed in the Spanish National Energy and Climate Plan to reduce greenhouse gas emissions, increase generation from renewable sources and reduce energy consumption. The empirical approach also includes differences between regions according to the expected effect for instruments. Findings – The application of this methodology to the environmental objectives defined in the current Spanish National Energy and Climate Plan for 2030 concludes that it is clearly possible to reduce the social cost of decarbonisation while improving environmental performance through a reorientation of investment instruments. In this case, such a reorientation would be based on a minimisation of efforts in thermal insulation of households and a maximisation of measures aimed at the installation of heat pumps. Originality/value – The paper proposes a novel methodology for a social cost assessment that improves the allocation of a portfolio of environmental instruments. This portfolio could be extended in further work to include instruments related to transport or support for industrial decarbonisation, such as the deployment of renewable hydrogen, among others.

Thermoacoustic heat pumps are a promising heating technology that utilizes medium/low-grade heat to reduce reliance on electricity. This study proposes a single direct-coupled configuration for a thermoacoustic heat pump, aimed at minimizing system complexity and making it suitable for domestic applications. Numerical investigations were conducted under typical household heating conditions, including performance analysis, exergy loss evaluation, and axial distribution of key parameters. Results show that the proposed thermoacoustic heat pump achieves a heating capacity of 5.7 kW and a coefficient of performance of 1.4, with a heating temperature of 300 °C and a heat-sink temperature of 55 °C. A comparison with existing absorption heat pumps reveals favorable adaptability for large temperature lift applications. A case study conducted in Finland over an annual cycle analyzes the economic and environmental performance of the system, identifying two distinct modes based on the driving heat source: medium temperature (≥250 °C) and low temperature (

A solar-assisted heat pump system is a hybrid system that integrates a solar collector and a heat pump, serving diverse functions such as space conditioning, drying, and generating heated water. The system's classification is based on the connection configuration of the solar collector and heat pump, which may involve a serial, parallel, or dual arrangement. Solar-assisted heat pump systems enhance output efficiency by harnessing solar energy in various heating modes, with the effectiveness contingent on the prevailing environmental conditions. As stated above, these systems are essential in lowering power consumption and reducing emissions. This study comprehensively assesses the research and development of solar-assisted heat pumps for building applications. This study delves into the classification of these systems, including direct expansion and indirect expansion solar-assisted heat pumps. Each configuration is to be detailed, and their thermal performance and demonstration samples are thoroughly examined. Furthermore, the study includes the assessment of energetic indicators for individual components and the overall system. Additionally, an investigation has been conducted on various refrigerant types that show promising potential for use in solar-assisted heat pump systems. It shows that adding an air evaporator to direct expansion solar-assisted heat pump solves the systems' deterioration during the absence of solar energy. The effect of climate on the indirect solar-assisted heat pump can be solved by designing the system to work in parallel or series configuration, depending on the solar energy availability.

In order to meet the demand for dual-temperature heating in production and life, a dual-temperature heat pump system based on refrigerant leakage was proposed. By establishing and verifying the mathematical model and system model of the scroll compressor based on refrigerant leakage for numerical simulation, the system was calculated and analyzed under different discharge outlet positions, discharge outlet sizes, evaporation temperatures, high-temperature condensation temperatures, and medium-temperature condensation temperatures. The changing trends of performance parameters were compared with traditional dual-temperature heat pump systems. The results show that the sooner the middle discharge port of the compressor is opened, the less power the compressor consumes, and the larger the discharge port is, the more obvious the energy-saving effect of the system is; Compared with the traditional dual-temperature heat pump system, the heating performance coefficient is significantly improved under different working conditions, with the highest of 16%. The model proposed in the study provides a more effective method for the theoretical analysis of refrigerant leakage dual-temperature heat pumps and air-supplemented enthalpy-increasing heat pump systems, and the research results provide a theoretical basis for the optimization of scroll compressor performance, and the research, design and system performance improvement of dual-temperature heat pump systems.

Abstract The development of electric vehicles (EVs) exhibits rapid and remarkable progress nowadays, serving as a crucial route to accomplish the target of mitigating greenhouse gas emissions. As an integral part of the thermal management system oriented toward electric vehicles, the heat pump air conditioning system for electric vehicles is the result of a comprehensive choice that trades off the cooling and heating performance, environmental performance and economic cost. Particularly, different regions around the world suffer varying cooling and heating challenges due to the complicated climatic characteristics. Thus the most suitable refrigerant and system cycle structure may differ. This paper focuses on evaluating both the refrigerants and cycle structures to screen the most suitable choice. According to the climate conditions of different cities, the annual energy consumption, life cycle climate performance, and economic cost of the basic system (Base), two-stage compression system (TSC,IC), and vapor injection (VI) system with CO2, R134a, and R1234yf refrigerants respectively, are quantitatively analyzed and evaluated. Subsequently, through comparative analysis, a comprehensive selection map for heat pump systems in electric vehicles worldwide is developed and the most suitable heat pump air conditioning system for each cites is determined. The results can provide a selection reference and decision-making for the air conditioning system of electric vehicles from regional considerations. It was found that the CO2 HPACVI was recommended for cold regions to meet both environmental and economic requirements. In warm region, the R1234yf HPACBase system was recommended to be used. For regions transitioning from cold to warm climates, the R1234yf HPACVI system was suggested. In hot region, the R1234yf AC system was recommended.

Drying enhances the attributes of biomass, such as storability and heating value. In regions with low solar radiation, solar drying has demonstrated limited economic viability. Hybrid systems, combining solar drying with a stable heat source such as a heat pump, present an opportunity to improve drying performance and achieve cost savings, especially with time-variable electricity pricing. To quantify this potential, we constructed an experimental drying system in Finland, incorporating an air-source heat pump and solar thermal collectors for drying woody biomass. Experimental work, consisting of 316 h of operation in varied conditions, evaluated the performance of the hybrid drying system. Subsequently, we developed data-driven models to estimate drying rates and power consumption in both hybrid and solar operation modes. Finally, these models were integrated into a techno-economic optimization model to assess the economic feasibility of the concept through hourly simulations. Hybrid drying experiments resulted in a significantly improved average drying rate (33.0 kg/h ± 5.4 kg/h) compared to solar drying (9.0 kg/h ± 3.2 kg/h) with a 45% increase in specific electricity consumption. The experimental work also revealed limited operating flexibility in colder temperatures due to an exponentially increasing preheating time (up to 4.2 h at 0 °C). With techno-economic modelling, the simulations yielded a simple payback time of 7.5 years for a commercial-scale drying system without investment subsidies. Applying an optimized operating strategy, system operation shifted on average from hybrid mode (96–33%) to solar mode (3–36%) and inactive state (1–31%) with an increased electricity price level, highlighting the need for advanced operation planning. Commercial deployment should prioritize use cases with high value increase through drying or obtaining compensation from avoided biogenic CO2 emissions through drying, as these two parameters were shown to have the greatest impact on the investment payback time.

In this study, the potential implementation of three different low-GWP refrigerants (R32, R452B, and R454B) as replacements for R410A was investigated. The study was performed using a simulation tool developed by the authors called RACHP-Lab, which is a vapor compression system simulation tool developed based on physics-based simulation for typical mini-split air conditioners. The simulation study was carried out and validated using experimental performance data of 10 different air conditioning units available in the Egyptian market. The units included fixed-speed or variable-speed compressors and operated in cooling or heating modes. Drop-in replacement with the new refrigerants was carried out. For R32, the capacity increased between 4.9% and 13% for cooling cases, and 6.3% and 12.4% for heating cases. However, COP did not improve in all cases. For R452B and R454B with direct replacement, the capacity nearly remained the same, with an increase of COP between 1.6% and 8.0%. Soft optimization was also conducted on cooling cases where compressor suction superheat, condenser subcooling, and compressor volumetric speed were optimized to maximize COP while maintaining the original capacity of R410A. R32 showed an improvement of COP over R410A between 4.6% and 15.5%, while for R452B and R454B between 2.2% and 13.2%.

The incorporation of ejectors into heat pump and refrigeration cycles has been the subject of growing interest, largely due to their simple structure, high reliability, and cost-effectiveness. This paper investigates the recent advancements in novel design concepts of ejector-enhanced vapor compression heat pump and refrigeration cycles. An overview of novel single-stage and two-stage compression cycles utilizing a single or multiple ejectors is provided. First, the system setup, operational principles, description, and figures of the existing schemes are provided. Second, the main results, such as the coefficient of performance (COP), volumetric heating capacity and exergy destruction, are discussed. In conclusion, the paper presents a coherent summary of the current developments, future prospects, and the current knowledge gap. A plethora of research is present in developing theoretical systems with high efficiency. However, experimental tests for real-life implementations are limited. This review aims to provide the reader with an overview of recent theoretical and experimental studies. [ABSTRACT FROM AUTHOR]

This feasibility study investigates extracting thermal energy from the Bedretto tunnel in the Swiss Alps, which benefits from subsurface heat flux and rock overburden insulation. Using the simulation software COMSOL Multiphysics, we created a numerical model of the tunnel environment to evaluate which medium between rock, air, and water serves as the most effective heat source. Our findings indicate that flowing water is the most effective heat source. Potential applications include distributing the water to nearby villages and storing remaining heat in the subsurface. Estimates indicate that the total extractable thermal energy ranges between 0.8 MWth and 1.5 MWth after reducing the water temperature to 4 °C via a heat pump. The study identifies the most suitable energy sourcing locations based on efficiency and investment costs. Circulating water to individual heat pumps in Bedretto, with the natural elevation difference, enables water transport without a pump. Cost analyses reveal that the investment in piping and heat pumps can be amortized within the equipment's lifespan with appropriate economic models. With the same initial investments, district heating systems are viable in villages with over 30 connections. The payback periods are 10 years for 60 connections, 4.5 years for 90 connections, and immediate for 200 connections. [ABSTRACT FROM AUTHOR]