Reversible Heat Research Articles

Effect of cyclic loading on microstructure and plastic deformation in heat-treated Co–28Cr–6Mo alloy fabricated via laser powder bed fusion: an in situ synchrotron X-ray diffraction study.

We present a systematic microstructure-oriented plasticity investigation of an additively manufactured cobalt-based alloy aiming to relate microstructural changes to the fatigue resistance. A load-controlled cyclic test in the low-cycle fatigue regime was utilized to study mechanical response and microstructural changes in the alloy after reverse phase transformation heat treatment. Deformation-induced FCC → HCP phase transformation was followed using in situ synchrotron X-ray diffraction combined with ex situ electron backscatter diffraction and scanning electron microscopy. Scanning transmission electron microscopy provided experimental evidence of the presence of precipitates in the solution annealed sample. It was found, that a stepwise increase in plastic deformation is attributed to nucleation and growth of different martensitic crystallographic variants. These insights into plasticity and microstructural changes suggest that the reverse phase transformation heat treatment is an effective approach for improving the fatigue resistance of low stacking fault energy alloys, that are susceptible to deformation-induced martensitic transformation.

Experimental characterization of a reversible heat pump – Organic Rankine cycle pilot plant as a thermally integrated Carnot battery

This paper reports a first detailed experimental characterization of a reversible heat pump – Organic Rankine Cycle pilot plant, presenting its potential as a thermally integrated Carnot battery for efficient energy storage. A total of 150 stationary operating points were investigated in both heat pump and ORC modes. The study analyzes and discusses the main trends and interactions on system and component level. As expected, heat pump and ORC operation show an opposing behavior. While heat pump operation yields a maximum COP of 9.5 at a 15 K temperature lift, the peak net ORC efficiency reaches 4.4 % with a 40 K temperature gradient. If additional storage losses are neglected, this leads to a power-to-power (round-trip) efficiency of up to 41.8 % for the Carnot battery. The absence of a liquid receiver in the ORC mode leads to notable subcooling and increased condensation pressures, impacting the expander’s power generation due to excess refrigerant accumulation. Moreover, the experimental results reveal that the reversible screw machine is the critical factor influencing efficiency. The screw machine’s maximum isentropic efficiencies are 78 % and 66 % in compressor and expander operation, respectively. The reliability of the results was verified by means of an energy balance and reference operating points, underlining high reproducibility. Additionally, potential system improvements were derived from the experimental results. Altogether, this paper successfully proofs the concept of reversible heat pump – ORC systems and provides experimental results for ongoing advancements in this field.

Advanced Wastewater Treatment: Synergistic Integration of Reverse Electrodialysis with Electrochemical Degradation Driven by Low-Grade Heat

The reverse electrodialysis heat engine (REDHE) represents a transformative innovation that converts low-grade thermal energy into salinity gradient energy (SGE). This crucial form of energy powers reverse electrodialysis (RED) reactors, significantly changing wastewater treatment paradigms. This comprehensive review explores the forefront of this emerging field, offering a critical synthesis of key discoveries and theoretical foundations. This review begins with a summary of various oxidation degradation methods, including cathodic and anodic degradation processes, that can be integrated with RED technology. The degradation principles and characteristics of different RED wastewater treatment systems are also discussed. Then, this review examines the impact of several key operational parameters, degradation circulation modes, and multi-stage series systems on wastewater degradation performance and energy conversion efficiency in RED reactors. The analysis highlights the economic feasibility of using SGE derived from low-grade heat to power RED technology for wastewater treatment, offering the dual benefits of waste heat recovery and effective wastewater processing.

Transported Entropy of Ions and Peltier Coefficients in 8YSZ and 10Sc1CeSZ Electrolytes for Solid Oxide Cells.

In this study, the transported entropy of ions for 8YSZ and 10Sc1CeSZ electrolytes was experimentally determined to enable precise modeling of heat transport in solid oxide cells (SOCs). The Peltier coefficient, crucial for thermal management, was directly calculated, highlighting reversible heat transport effects in the cell. While data for 8YSZ are available in the literature, providing a basis for comparison, the results for 10Sc1CeSZ show slightly smaller Seebeck coefficients but higher transported ion entropies. Specifically, at 700°C and an oxygen partial pressure of pO2=0.21 bar, values of SO2-*=52±10 J/K·F for 10Sc1CeSZ and SO2-*=48±9 J/K·F for 8YSZ were obtained. The transported entropy was also validated through theoretical calculations and showed minimal deviations when comparing different cell operation modes (O2||O2-||O2 and H2, H2O||O2-||O2). The influence of the transported entropy of the ions on the total heat generation and the partial heat generation at the electrodes is shown. The temperature has the greatest influence on heat generation, whereby the ion entropy also plays a role. Finally, the Peltier coefficients of 8YSZ for all homogeneous phases agree with the literature values.

Numerical investigation of the effect of the structure and number of spiral baffles on the vibration and heat transfer coefficient of spiral tubes within spiral tube heat exchangers

In response to the advantages of compactness and high efficiency of spiral elastic tube heat exchanger and its easy-to-vibrate characteristics, this study aims to further improve its heat transfer efficiency by utilizing fluid-induced vibration-enhanced heat transfer technology, so a design scheme of reverse baffle spiral tube heat exchanger (RB-STHE) is proposed to enhance the turbulence characteristics of the shell-side fluid by installing spiral baffles, thus promoting the vibration of the spiral tube. In this study, four new types of the RB-STHE (Model A, B, C, and D) were used as research objects, and the two-way fluid–structure coupling calculation method (using CFX and Transient Structure software) was adopted to systematically investigate the effect of fluid-induced spiral tube vibration on the comprehensive heat transfer coefficient (HTC) of the RB-STHE under different flow velocities and structure schemes, and based on the research data, the objective of no reduction in the comprehensive HTC and savings in the use of materials is taken as the goal, so as to put forward the improved Model C-1. The results show that: although the fluid-induced spiral tube vibration can effectively improve the HTC of the spiral tube, it also increases the pressure drop in the RB-STHE, and the larger the amplitude, the higher the degree of influence; among them, Model C is most affected by the spiral tube vibration, and its HTC and pressure drop are maximally enhanced by 6.33% and 5.85%, respectively. The change in the number of baffles has a significant effect on the comprehensive HTC of the RB-STHE. Compared to the Model D without a spiral baffle, the maximum improvement in the comprehensive HTC of Model C with one spiral baffle installed in the RB-STHE is 14%, while the Model A with four spiral baffles and the Model B with two spiral baffles have a maximum reduction in the comprehensive HTC of 20% and 3%, respectively. In addition, compared to Model C, the structure improved Model C-1 significantly reduces the size of the spiral baffle while effectively maintaining the comprehensive HTC of the RB-STHE, making the structure more reasonable, which provides a reference for heat exchanger design.

Experimental determination of the entropic heat coefficient of a lithium-ion cell through immersion in a dielectric fluid

The heat generation of a lithium-ion cell is predominantly comprised of irreversible and reversible heating, with the latter term dictated by the entropic heat coefficient which describes the variation of the cell’s open circuit voltage with respect to temperature. The entropic heat coefficient is also dependent upon the cell’s state of charge, and the correct description of its behaviour is required to implement numerical and analytical models which accurately describe the heat generation rate of lithium-ion cells. In this study, the entropic heat coefficient of a single 26,650 LiFePO4 cylindrical lithium-ion cell is determined through a novel liquid immersion experimental set-up, offering greater thermal uniformity and control in comparison to the environmental chambers typically utilised. The arrangement is more cost effective and easily implemented in a laboratory setting, with a thermal non-uniformity of 0.2 °C and setpoint stability of ± 0.1 °C achieved. The entropic heat coefficient is determined for six setpoint temperatures in the range of 15 °C to 40 °C across the cell’s entire state of charge, which is adjusted in increments of 10 %. This work also details the influence of open circuit voltage instability arising from cell self-discharge and relaxation, and a method to adjust for its effect is proposed and implemented. The entropic heat coefficient is subsequently utilised to determine the heat generation rate of the cell under two-phase liquid immersion cooling conditions.

Heat engines with finite reservoirs

Typical textbook analyses of heat engines assume that the temperatures of thermal reservoirs do not change; that is, the reservoirs have infinite heat capacity. Several authors have investigated the performance of reversible heat engines for which reservoirs have finite heat capacities and thus the reservoir temperatures do change with time. We find that previous studies have been too restrictive in that they assumed that the reservoir temperature change per cycle is infinitesimal and that the engine ceases operation when the hot reservoir cools to match the temperature of the cold reservoir. We model a Carnot-like engine and show that (1) the problem can be solved exactly with no requirement for infinitesimal temperature changes and (2) there is nothing special about the instant when the temperatures converge, with the device transitioning smoothly from a heat engine to a refrigerator. We find explicit expressions for the limiting reservoir temperature and the total efficiency.

Smart temperature-adaptive thermal regulation textiles integrating passive radiative cooling and reversible heat storage

Passive radiative cooling (PRC) textiles have garnered significant interest in next-generation wearable technology. However, current PRC textiles often fail to regulate temperature effectively throughout the day due to unnecessary cooling at nighttime. Herein, a smart temperature-adaptive thermal regulation (STATR) textile seamlessly integrating PRC technology and phase-change heat storing/releasing strategy is developed on a bilayered configuration. Highly temperature-sensitive heat-storing microparticles constructed by phase change microcapsule (PCM) core and tightly incorporated BN nanoparticle shell are designed, which is homogeneously encapsulated in ultra-stretchable nonwoven microfibers for thermal energy storage in hot daytime and heat release in cold nighttime. Moreover, TiO2 microparticle-embedded PRC fibers with high emissivity (maximum emissivity>97 %) and reflective porosity (sunlight reflectivity>90 %) are assembled on the heat-storing layer, obtaining the bilayered STATR textile with a remarkable passive cooling effect during the day (10.6°C and 4.2°C compared to pristine textile and PRC textile) and a long-term heating performance at nighttime (2.1°C above pristine textile). Concurrently, the collaboration of asymmetric porosity and wettability in the bilayered STATR textile simultaneously facilitates efficient perspiration, thereby also ensuring lengthy wet comfort on human skin. Therefore, this STATR textile opens a promising avenue for zero-energy and all-weather thermal regulation technology.

Reversible Solar Heating and Radiative Cooling Devices via Mechanically Guided Assembly of 3D Macro/Microstructures.

Solar heating and radiative cooling are promising solutions for decreasing global energy consumption because these strategies use the Sun (≈5800K) as a heating source and outer space (≈3K) as a cooling source. Although high-performance thermal management can be achieved using these eco-friendly methods, they are limited by daily temperature fluctuations and seasonal changes because of single-mode actuation. Herein, reversible solar heating and radiative cooling devices formed via the mechanically guided assembly of 3D architectures are demonstrated. The fabricated devices exhibit the following properties: i) The devices reversibly change between solar heating and radiative cooling under uniaxial strain, called dual-mode actuation. ii) The 3D platforms in the devices can use rigid/soft materials for functional layers owing to the optimized designs. iii) The devices can be used for dual-mode thermal management on a macro/microscale. The devices use black paint-coated polyimide (PI) films as solar absorbers with multilayered films comprising thin layers of polydimethylsiloxane/silver/PI, achieving heating and cooling temperatures of 59.5 and -11.9°C, respectively. Moreover, mode changes according to the angle of the 3D structures are demonstrated and the heating/cooling performance with skin, glass, steel, aluminum, copper, and PI substrates is investigated.

Light/electro-thermal conversion of carbonized sweet potato 3D grid-supported PEG shape-stable phase change materials for thermal management applications

Phase change materials (PCMs) are functional energy-storage materials that achieve reversible heat storage and release through phase transition processes. They have extensive applications in the thermal management and solar energy industries. However, their low electrical and thermal conductivities and poor stability often fail to meet application requirements. In this study, we utilised an abundant biomass-derived carbon source, sweet potatoes, to prepare a three-dimensional network of carbon aerogels. By simply vacuum-impregnating polyethylene glycol (PEG), the PCM was embedded in the carbon aerogel. The obtained PEG/carbon aerogel composite material exhibited high enthalpy (158.1 J/g) and good thermal and shape stability. They also demonstrated efficient photothermal (88.47 %) and electrothermal conversion (94.02 %). This research has significant potential for applications in solar energy storage and utilisation, building energy storage, space–ground thermal energy storage, and electronic device thermal management. This study provides a novel approach for the preparation and photothermal applications of bio-based PCMs.

Experimental investigation of a small-scale reversible high-temperature heat pump − organic Rankine cycle system for industrial waste heat recovery

Innovative technologies are required to mitigate the challenges of climate change. A reversible high-temperature heat pump (HTHP) − organic Rankine cycle (ORC) system can be used for effective utilisation of industrial waste heat in the lower temperature band <100 °C. The system can provide useful process heat for industrial processes by operating in HTHP mode or generating power in ORC mode. This paper presents the experimental investigation of the reversible system in both HTHP and ORC modes. A single scroll unit was selected for the compressor (HTHP) and expander (ORC) roles, keeping the system compact. A HCFO refrigerant, R1233zd(E), with a low GWP value, was chosen as the working fluid for both operating modes. When operated in HTHP mode, a maximum compressor overall isentropic efficiency of 73.4 % and a COPmech of 4.8 (ΔTlift,rside = 41 K, Tsf,ev,in = 60 °C) was obtained. In ORC mode, the maximum net power output was 512.4 W (Tsf,ev,in = 90 °C, rp = 2.3), overall cycle efficiency was 3.01 %, and overall isentropic efficiency of the expander was 54.6 %. The technical limitations encountered, and solutions put in place during the experimental testing campaign are discussed in detail.

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.

Enhancing life cycle assessment for reversible ground-coupled heat pump systems through dynamic analysis

Ground-coupled heat pump (GCHP) systems can provide comfortable indoor environments, but also inevitably contribute to greenhouse gas emissions and other impacts on human health, ecosystems, and resources. Life cycle assessment (LCA) methodology has been widely adopted to estimate the environmental impacts associated with GCHP systems, with operational electricity consumption being the largest contributor among most categories. Given the data-intensive nature of LCA, operational electricity consumption should be prioritised to refine the accuracy of LCA results. Previous studies, however, have relied on static COP (Coefficient of Performance) and annual average data to obtain the environmental impacts and have disregarded the effect of long-term performance degradation caused by building thermal load imbalances. In this paper, to bridge this research gap, a dynamic operational environmental impact assessment (DOEIA) method was proposed to improve the precision of LCA results by incorporating higher temporal resolution data of electricity mix and real-time performance modelling of the reversible GCHP system. Impacts of different temporal resolutions (i.e. monthly, trimestral, and annual) on the accuracy of LCA results was examined and the operational performance degradation resulting from imbalanced building heating and cooling loads was considered. Results demonstrate that while performance degradation effects are evenly distributed across impact categories, gaps due to temporal resolutions vary significantly between different categories. Subsequent analysis of spatial variations in the latter further emphasises the importance of accounting for higher temporal resolutions. Finally, life cycle impact assessment (LCIA) results for reversible GCHP systems in different locations were obtained with the support of DOEIA method and the results underscore the necessity of a cleaner energy mix. The proposed DOEIA method can be applied to other energy systems for comparative analyses. It is replicable in other countries and regions and therefore is expected to provide methodological guidance for future decision-makers.

Development of novel thermal diode inspired by the structure of venous valve

To increase the unidirectional heat transfer capability of a thermal diode, a novel thermal diode with unidirectional movable valves as vapor channel is proposed based on the structure of venous valves. The thermal performance of this bionic thermal diode was experimentally investigated under different working conditions. The results demonstrate that the bionic thermal diode exhibits a high thermal rectification ratio and strong stability. The best thermal rectification ratio is 10.79, with a forward thermal resistance of 0.26 °C/W and a reverse thermal resistance of 2.86 °C/W, at a heating power of 15 W and a filling ratio of 15 %. The temperature distribution indicated that, under the reverse heat transfer mode, the vapor was obstructed at the first valve, leading to the high thermal resistance of thermal diode. Additionally, the effect of inclined angle on the thermal performance of thermal diode was also investigated. This study provides a novel approach for the design of thermal diodes.

Improving intergranular cracking and stress corrosion cracking resistance of highly sensitized AA5083 Al-Mg alloy via reversion heat treatment

This study systematically examines the impact of reversion heat treatments (220–280 ℃ for 1 h) on the microstructure evolution, electrochemical corrosion, intergranular cracking (IGC) and stress corrosion cracking (SCC) of a severely sensitized (175 ℃/100 h) AA5083 alloy. Increasing the reversion temperature gradually enhances the corrosion resistance by dissolving the β′-Al3Mg2 phase, with the optimal treatment identified as 280 ℃/1 h. The βˊ phase maintains its planar film shape and continuously covers the grain boundaries after reversion treatment below 240 °C, but spheroidizes at the triple junctions at 260 °C. The morphology of the βˊ phase is dictated by grain boundary diffusion and interface diffusion. Reversion treatments improve SCC resistance by dissolving the β′ phase and reducing yield strength, attributed to anodic dissolution and hydrogen embrittlement mechanisms. This research offers valuable insights into the practical benefits of reversion treatments for Al-Mg alloy marine applications, addressing safety concerns related to sensitization.

Explainable artificial intelligence prediction of defect characterization in composite materials

Non-destructive evaluation (NDE) techniques are integral across diverse applications for void detection within composites. Infrared (IR) thermography (IRT) is a prevalent NDE technique that utilizes reverse heat transfer principles to infer defect characteristics by analyzing temperature distribution. Although the forward heat transfer problem is well-posed, its inverse counterpart lacks uniqueness, posing non-unique solutions. The present study performs simulations using finite element analysis (FEA) in defective (a penny-shaped defect) composites through which the heat transfer flux is modeled. A total of 2100 simulations with various defect positions and sizes (depth, size, and thickness) are executed, and the corresponding surface temperature vs. time and vs. distance diagrams are extracted. The FEA outputs provide ample input data for developing an explainable artificial intelligence (XAI) model to estimate the defect characteristics. A detailed feature engineering task is performed to select the representative information from the diagrams. Explainable decision tree-based machine learning (ML) models with transparent decision paths based on derived features are developed to predict the defect depth, size, and thickness. The ML models’ results suggest superb accuracy (R2 = 0.92 to 0.99) across all three defect characteristics. The provided workflow sets a benchmark applicable to a range of fields, including health monitoring.

Investigation on heat generation in fast charging of lithium-ion batteries: Effect of charging rate and battery component thickness

Understanding heat generation mechanisms during fast charging is essential for designing and optimizing lithium-ion batteries. In this study, we have formulated a three-dimensional electrochemical-thermal coupling model for pouch lithium-ion batteries. The model is validated by the experimental results based on the distribution of temperature, current, and voltage. We investigate the effects of charging rate, active material coating thickness, and current collector thickness (each at three levels) on heat generation and temperature distribution. The electrodes account for most of the total heat generation (87.5% with a 2.5C charging rate), and the percentage decreases as the charging rate increases. The heat generated at the negative electrode is slightly higher than that at the positive electrode. Reversible heat is the main heat source at a low charging rate, and it decreases as the charging rate rises. The effects of battery component thicknesses on thermal behaviors under fast charging are significant. The overall battery temperature increases by 11.5 K as the positive electrode thickness increases from 40 to 70 µm due to the rise in ohmic resistance and polarization resistance within the electrode. The increased ohmic resistance in the separator and the current collector raises the temperature. Reducing the thickness of the current collector by 33% resulted in a doubling of heat generation from the current collectors. Yet, it had minimal impact on the overall temperature of the battery.

Development of a Fast Running Equivalent Circuit Model with Thermal Predictions for Battery Management Applications

Equivalent circuit modelling (ECM) is a powerful tool to study the dynamic and non-linear characteristics of Li-ion cells and is widely used for the development of the battery management system (BMS) of electric vehicles. The dynamic parameters described by the ECM are used by the BMS to estimate the battery state of charge (SOC), which is crucial for efficient charging/discharging, range calculations, and the overall safe operation of electric vehicles. Typically, the ECM approach represents the dynamic characteristics of the battery in a mathematical form with a limited number of unknown parameters. Then, the parameters are calculated from voltage and current information of the lithium-ion cell obtained from controlled experiments. In the current work, a faster and simplified first-order resistance–capacitance (RC) equivalent circuit model was developed for a commercial cylindrical cell (LGM50 21700). An analytical solution was developed for the equivalent circuit model incorporating SOC and temperature-dependent RC parameters. The solution to the RC circuit model was derived using multiple expressions for different components like open circuit voltage (OCV), instantaneous resistance (R0), and diffusional parameters (R1 and C1) as a function of the SOC and operating temperature. The derived parameters were validated against the virtual HPPC test results of a validated physics-based electrochemical model for the voltage behavior. Using the developed RC circuit model, a polynomial expression is derived to estimate the temperature increase of the cell including both irreversible and reversible heat generation components. The temperature predicted by the proposed RC circuit model at different battery operating temperatures is in good agreement with the values obtained from the validated physics model. The developed method can find applications in (i) onboard energy management by the BMS and (ii) quicker evaluation of cell performance early in the product development cycle.

Net Zero Energy Building technologies – Reversible Heat Pump/Organic Rankine Cycle coupled with Solar Collectors and combined Heat Pump/Photovoltaics – Case study of a Chilean mid-rise residential building

In the following years, the building sector will have to considerably reduce its final energy demand and emissions by adopting new technologies.This paper introduces two innovative technologies capable of reducing the final energy demand of residential buildings: A Heat Pump/Organic Rankine Cycle system coupled to solar thermal collectors (HP/ORC-COL), and a Heat Pump coupled with Photovoltaic panels (HP-PV). The HP/ORC-COL system alternates between generating either heat or electricity, whereas the HP-PV system produces them separately. The goal is to compare both systems through their Seasonal Performance Factor (SPF), equivalent emissions, operational cost, and Net Zero Energy Building (NZEB) potential. Additionally, the impact on the heating demand of retrofitting existing buildings with the Passivhaus Standard is studied.The heating, domestic hot water, and electricity demands are determined by considering the climate conditions of three polluted Chilean cities: Santiago, Concepción, and Temuco. The proposed systems are evaluated through numerical models developed in Python and validated with data from manufacturer catalogues. The validation of the models allows to enhance the result accuracy of the integrated overall model by closely aligning outputs with real conditions, and therefore increases the reliability of the prediction on the potential of the building to reach net zero energy.Results show that applying the Passivhaus standard allows to reduce heating requirements by up to 30% in all cities. The SPF and electricity production of the HP-PV system is better than the HP/ORC-COL, reaching a NZEB potential of 76.3% in Santiago, 66.6% in Concepción and 60.4% in Temuco. The average cost reduction of the HP/ORC-COL system compared to oil, natural gas, and wood pellet boilers is 82.7%, 90.4%, and 72.3%, whereas for the HP-PV system is 93.3%, 96.3%, and 89.2% respectively. On the CO2 emissions, the HP/ORC-COL system presents an average reduction of 63.6% and 59.7% compared to an oil and natural gas boiler, while the HP-PV system has an average reduction of 72.5% and 69.5% respectively.

Operation strategy optimization and heat transfer characteristic analysis of photovoltaic/thermal module series connected with flat plate solar collector: System experimental study

Flat plate solar collector (FPSC) produces only thermal energy without electricity, whereas the photovoltaic thermal (PV/T) module produces electricity and low-temperature thermal energy. This paper presents a low-cost method to strengthen the functional uniqueness of individual PV/T and FPSC components through connecting a PV/T module in series with the other component. Under various water volume conditions, an experimental test on high mass flow rate was carried out. Results showed that the FPSC produced a better heating contribution and that reverse heat transfer of the PV/T module might be reduced by changing the operation strategy. The water volume is a crucial factor that influences the system's available heating time, a system that operates in the optimal water volume range will produce greater energy savings. Furthermore, the maximum values of the thermal, electrical, exergy, and primary energy-saving efficiency were 51.91 %, 13.52 %, 19.13 %, and 87.20 %, respectively. The optimal water volume distribution range of the system is 160–180 L. With an average annual decrease of 2.96 t in CO2 emissions, the system provides a 4.28-year payback period and saves 5285.71 USD in electricity costs throughout its life cycle. The novel system performs extremely well in terms of energy and cost efficiency.