Weixiu Shi , Haiyu Chang , Xuebing Liu , Lisheng Pan
{"title":"Phase transition and agglomeration characteristics of fine particles in humid flue gas flowing through perpendicular pipe arrangement","authors":"Weixiu Shi , Haiyu Chang , Xuebing Liu , Lisheng Pan","doi":"10.1016/j.applthermaleng.2025.127332","DOIUrl":"10.1016/j.applthermaleng.2025.127332","url":null,"abstract":"<div><div>The excessive emission of particulate matter and the waste of residual heat are major issues in the flue gas emission process. By arranging perpendicular pipe turbulence heat exchange devices in the flue gas, it is possible to achieve flue gas heat recovery and fine particles agglomeration during water vapor phase change process. A numerical calculation model of the particle agglomeration process was established, involving turbulent agglomeration, Brownian agglomeration and vapor phase-change agglomeration. The influence of flue gas particle concentration, flue gas temperature, flue gas flow rate, flue gas humidity, heat exchange device wall temperature and structure on the agglomeration of particles was studied. The results indicate that an increase in particle concentration can enhance agglomeration efficiency, while excessively large or small particle sizes can reduce this efficiency. A decrease in flow velocity provides particles with more residence time within the heat exchanger, thereby improving agglomeration efficiency. A drop in flue gas temperature weakens convective heat transfer and vapor-phase condensation, leading to decreased agglomeration efficiency. Condensation of water vapor on particle surfaces promotes particle agglomeration efficiency. Lower wall temperatures and higher water vapor volume fractions increase the amount of vapor condensation, leading to more particles agglomeration under the influence of condensation. The use of staggered arrangements in the structure also helps improve particle agglomeration efficiency.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127332"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A fast and accurate Data-Driven Model for estimating the production temperature of High-Temperature Aquifer Thermal Energy Storage","authors":"David Geerts , Alexandros Daniilidis , Wen Liu","doi":"10.1016/j.applthermaleng.2025.126817","DOIUrl":"10.1016/j.applthermaleng.2025.126817","url":null,"abstract":"<div><div>High-Temperature Aquifer Thermal Energy Storage (HT-ATES) has the potential to significantly increase the renewable heat share in heating systems. However, HT-ATES has not been implemented in the current energy system models because the widely applied numerical models for HT-ATES are computationally expensive. This leads to a lack of HT-ATES assessment from an energy system perspective. Therefore, an accurate and computationally efficient model that is widely applicable is needed to facilitate such implementation. This research aimed to develop a novel data-driven model that generates the temperature profile of an HT-ATES accurately and computationally efficiently. A trained machine learning algorithm predicts the recovery efficiency for an HT-ATES system, which, combined with other parameters, enables a nearest neighbor search to identify a suitable temperature profile. As a result, the temperature profile generated by the data-driven model has a root mean square error of 1.22 °C compared to the numerical model output. This error was shown to be larger for lower recovery efficiency values compared to higher values. The machine learning algorithm used to predict the recovery efficiency has a root mean square error of 1.45 percentage points. The data-driven model has a computation time of less than half a second, which is more than 180,000 times faster than the numerical model that was used to generate the data. This model is, therefore, suitable for integration in larger energy system models.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 126817"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144500874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xinyuan Liu , Yongqiang Shi , Lingling Chen , Qingzhen Yang , Yiwen Li , Huimin Xiang , Boxu Yang
{"title":"Numerical study of Ultraviolet and Infrared radiation characteristics of pulsed detonation engine exhaust","authors":"Xinyuan Liu , Yongqiang Shi , Lingling Chen , Qingzhen Yang , Yiwen Li , Huimin Xiang , Boxu Yang","doi":"10.1016/j.applthermaleng.2025.127246","DOIUrl":"10.1016/j.applthermaleng.2025.127246","url":null,"abstract":"<div><div>The radiation characteristics of pulsed detonation engine (PDE) exhaust have significant applications in engine performance monitoring, parameter inversion, and target detection. In this work, an effective model for predict the radiation characteristics of PDE exhaust is developed, both the Ultraviolet (UV) radiation from excited OH molecule (OH<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span>, <span><math><mrow><msup><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>Σ</mi></mrow><mrow><mo>+</mo></mrow></msup><mo>→</mo><msup><mrow><mi>X</mi></mrow><mrow><mn>2</mn></mrow></msup><msub><mrow><mi>Π</mi></mrow><mrow><mi>r</mi></mrow></msub></mrow></math></span>) and Infrared (IR) radiation from multiple species are considered. Specifically, the OH<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span> total number density is calculate by a combined chemical mechanism and the OH<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span> population is predicted based on an assumption of a local Boltzmann distribution within excited states. Furthermore, an enhanced Reverse Monte Carlo (RMC) method is proposed to address the radiation transfer. A three-dimensional transient PDE exhaust flow is simulated by Computational Fluid Dynamics (CFD), and the radiation characteristics of the exhaust are presented in detail. The results indicate that the developed model can calculate the exhaust radiation characteristics accurately. The PDE exhaust is similar to the supersonic free jet, with exhaust boundaries being more distinct in UV images, while IR images are more sensitive to shock structures. The <span><math><mrow><mn>0</mn><mo>.</mo><mn>31</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> and <span><math><mrow><mn>2</mn><mo>.</mo><mn>7</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> bands are identified as the two most distinctive spectral peaks, accompanied by several weaker peaks. Whether in the UV or IR band, the image radiance always decreases as the exhaust develops, while the spectral and integral intensities show different trends. The equivalence ratio has a significant impact, particularly on UV radiation. As the equivalence ratio increases, the UV radiation exhibits an enhancement by 1–3 orders of magnitude, while the variation in the IR radiation is relatively modest. The afterburning phenomenon influences UV radiation primarily by chemiluminescence reaction and IR radiation through heat release.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127246"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Weiming Ji , Feng Hong , Kang Li , Lu Liang , Junhong Hao , Fang Fang , Jizhen Liu
{"title":"Optimal dispatch of storage-assisted thermal power considering renewable uncertainties","authors":"Weiming Ji , Feng Hong , Kang Li , Lu Liang , Junhong Hao , Fang Fang , Jizhen Liu","doi":"10.1016/j.applthermaleng.2025.127276","DOIUrl":"10.1016/j.applthermaleng.2025.127276","url":null,"abstract":"<div><div>Energy storage systems have emerged as critical components in modern power systems, addressing the challenges of frequency regulation stability and renewable integration. Coal-fired thermal power plants have provided grid stability but now confront increasing demands for deep peak shaving services. However, energy storage systems are exposed to relatively low energy support duration while thermal power units confront slow power changing rate. This paper proposes a coordinated control strategy and a robust optimization model for storage-assisted thermal power units, addressing short-term fluctuations and long-term uncertainties imposed on thermal power units across multiple timescales. The Column-and-Constraint Generation approach is employed to improve computational efficiency, achieving convergence within three iterations for the optimal solution. Simulation results confirm that the proposed uncertainty set effectively adapts to increasing data dimensions, addressing over-conservatism in traditional models subject to multi-timescale uncertainties. By leveraging the rapid response capability of energy storage and the steady output of thermal power units, the model improves grid support and alleviates operational stress on thermal units. The results also reveal that three different energy storage systems configurations result in cost reductions of 23.50%, 41.78%, and 38.63%, respectively, while demonstrating a substantial improvement in the system’s resilience in response to short- and long-term challenges.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127276"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammad Reza Ahmadipour, Javad Mahmoudimehr, Masoud Hami
{"title":"A multi-criteria assessment to show the superiority of time-dependent heat flux over constant heat flux during direct heating of solid oxide fuel cell","authors":"Mohammad Reza Ahmadipour, Javad Mahmoudimehr, Masoud Hami","doi":"10.1016/j.applthermaleng.2025.127334","DOIUrl":"10.1016/j.applthermaleng.2025.127334","url":null,"abstract":"<div><div>Although the high operating temperature of solid oxide fuel cells (SOFCs) provides several advantages, it extends the heating time. Accelerating the heating process can lead to severe temperature gradients and consequent structural issues. Therefore, making a balance between the time and temperature gradient is crucial for SOFC’s practical development. Previous studies have considered constant heat flux for the direct heating process of SOFCs. This study, however, numerically assesses the benefits of employing time-dependent heat flux and identifies the best time-dependent heat flux function, using a multi-criteria approach. In this regard, various polynomial functions, including linear, quadratic, cubic, and quartic, along with their rotated forms are examined. The findings indicate that the variable heat flux function is superior to the constant one from a multi-criteria perspective (i.e., when heating time and temperature gradient are considered simultaneously). Among the examined functions, the linear rise function with a heat flux rise coefficient of 1 W s<sup>−1</sup>, which results in a heating time of 628 s and a maximum temperature gradient of 6.18 K cm<sup>−1</sup>, is identified as the optimal trade-off solution. The obtained results highlight the desirable potential of time-dependent heat flux functions in achieving a balance between temperature gradients and heating duration.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127334"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Muhammad Ihsan Shahid , Muhammad Farhan , Anas Rao , Xianlei Zhu , Qiuhong Xiao , Hamza Ahmad Salam , Tianhao Chen , Xin Li , Fanhua Ma
{"title":"Hydrogen production enhancement using exhaust heat from HCNG engine: ASPEN plus simulation and machine learning prediction","authors":"Muhammad Ihsan Shahid , Muhammad Farhan , Anas Rao , Xianlei Zhu , Qiuhong Xiao , Hamza Ahmad Salam , Tianhao Chen , Xin Li , Fanhua Ma","doi":"10.1016/j.applthermaleng.2025.127340","DOIUrl":"10.1016/j.applthermaleng.2025.127340","url":null,"abstract":"<div><div>Hydrogen production plays a pivotal role in advancing clean energy solutions for transportation and power generation. However, conventional methods face challenges due to their high energy requirements and inefficiencies. This study investigates a novel strategy to improve hydrogen production by integrating exhaust heat recovery from Hydrogen-enriched Compressed Natural Gas (HCNG) engines with the Steam Methane Reforming (SMR) process. The research analyzes hydrogen production by exhaust heat utilization at a hydrogen ratio of 20 %, an Exhaust Gas Recirculation (EGR) ratio of 24 %, an engine load of 75 %, and an engine speed of 1700 rpm under stoichiometric conditions. Hydrogen production via the SMR process is simulated using ASPEN Plus software, with a detailed evaluation of heat exchanger and reformer component heat duties. Results indicate that at 973 K, increasing the steam-to-methane ratio (S/C) from 1 to 6 leads to a rise in the hydrogen production rate from 4.01 kg/hr to 6.85 kg/hr. Additionally, the maximum heat recovered from the HCNG engine exhaust reaches 89.23 kW out of a total available 133.12 kW under the specified conditions. Another key objective of this study is to predict hydrogen production using machine learning regression models, including Stepwise Linear Regression (SLR), Decision Tree (DT), Linear Support Vector Machine (LSVM), and Boosted Tree (BT). The models are evaluated based on Root Mean Square Error (RMSE), Mean Absolute Error (MAE), coefficient of determination (R<sup>2</sup>), and computational time across different datasets and input parameters. Among the models, SLR demonstrates superior performance, achieving an RMSE of 0.514 with a single input and 0.074 with four inputs. The SLR showed the minimum MAE is 0.06 and the highest R<sup>2</sup> value is 0.99, which confirms the strong predictive ability. These findings contribute to the advancement of HCNG engines integrated with SMR and electronic control units, offering a pathway to more efficient and sustainable hydrogen production.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127340"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abd Alrhman Bani Issa , Changkuan Liang , Haotian Liu , Eckhard A. Groll , Davide Ziviani
{"title":"Experimental analysis of a liquid-to-liquid two-stage R290 heat pump system for residential cold-climate applications","authors":"Abd Alrhman Bani Issa , Changkuan Liang , Haotian Liu , Eckhard A. Groll , Davide Ziviani","doi":"10.1016/j.applthermaleng.2025.127223","DOIUrl":"10.1016/j.applthermaleng.2025.127223","url":null,"abstract":"<div><div>The phasedown of hydrofluorocarbon (HFC) refrigerants with high global warming potential (GWP), alongside growing restrictions on PFAS compounds, has intensified the search for sustainable and efficient alternatives in residential space conditioning. Propane (R290) has emerged as an appealing environmentally friendly refrigerant, but its flammability requires the utilization of indirect system architectures. In parallel, electrification efforts demand highly efficient heat pumps to replace traditional fossil fuel-based heating systems. This study experimentally evaluates a novel two-stage, variable-speed, liquid-to-liquid heat pump with R290 refrigerant for cold climates. Unlike prior studies, it introduces independent speed control of the low- and high-stage compressors, providing the first experimental dataset for R290 in two-stage systems. The system achieved an 18.3% increase in heating capacity and a 5.8% improvement in the coefficient of performance (COP) at an ambient temperature of −8.3 °C in two-stage mode compared to single-stage operation, although with an 11% increase in refrigerant charge level. The study also highlights the critical role of the secondary fluid in system design, overall performance, and thermal comfort. Namely, a design mismatch was identified between hydrocarbon refrigerants and aqueous secondary fluids in the evaporators of indirect systems operating at low evaporation temperatures. These findings provide key insights for designing high-performance regulation-compliant heat pumps suitable for safe residential use in cold climates.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127223"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Manzoore Elahi M. Soudagar , Arunkumar Munimathan , K. Senthil Kumar , Aman Sharma , Mamata Chahar , Lalitha Gnanasekaran , Ratchagaraja Dhairiyasamy , Manikandan Ayyar , Vinayagam Mohanavel
{"title":"Nanostructured coatings for enhanced photothermal conversion in solar desalination systems","authors":"Manzoore Elahi M. Soudagar , Arunkumar Munimathan , K. Senthil Kumar , Aman Sharma , Mamata Chahar , Lalitha Gnanasekaran , Ratchagaraja Dhairiyasamy , Manikandan Ayyar , Vinayagam Mohanavel","doi":"10.1016/j.applthermaleng.2025.127316","DOIUrl":"10.1016/j.applthermaleng.2025.127316","url":null,"abstract":"<div><div>Conventional solar driven desalination systems have suffers from low thermal efficiency and salt accumulation. This paper examines the use of black silicon and carbon nanotube based surface coatings to increase photothermal performance of solar desalination systems. The absorber plates were spray coated with these coatings using a low cost spray coating technique and tested in outdoors weather conditions. The maximum evaporation rate reached 2.65 kg/m<sup>2</sup>·h under solar irradiance of 870 W/m<sup>2</sup> for the coated system, compared to 1.12 kg/m<sup>2</sup>·h for the uncoated control. Consequently, more than 99 % of the total dissolved solids (TDS) concentration was removed from the collected water, as confirmed by spot water tests that fell within WHO’s potable water limits. First, the coatings showed sufficient thermal stability after 1000 h at 900 °C and a preliminary economic analysis indicated a projected coating cost ranging from USD 8–12/m<sup>2</sup> with a return on investment favorable for offgrid deployment. This work distinguishes itself from the previous studies by simply combining spectrally optimized nanomaterial with scalable fabrication with the evaluation of environmental impact, anti-fouling behavior and ion rejection mechanisms. These results indicate that black silicon–carbon nanotube composites are a durable, efficient and scalable approach toward sustainable solar based desalination technologies.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127316"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xing He, Zhicheng Ye, Ge Xia, Zemin Ding, Yongbao Liu
{"title":"Exploring the impact of pulse loads on the performance of micro power generation gas turbine coupled with flywheel energy storage","authors":"Xing He, Zhicheng Ye, Ge Xia, Zemin Ding, Yongbao Liu","doi":"10.1016/j.applthermaleng.2025.127339","DOIUrl":"10.1016/j.applthermaleng.2025.127339","url":null,"abstract":"<div><div>This study investigates the impact of rectangular and triangular pulse loads on a 100kW micro gas turbine power generation system integrated with a flywheel energy storage system for naval applications. A MATLAB/Simulink model, validated against experimental data from a DC microgrid platform, analyses key performance parameters including compressor outlet pressure, combustor temperature, turbine speed, and DC bus voltage under varying duty cycles (40 %, 60 %, 80 %) and peak power conditions (32 kW, 70 kW). Results demonstrate that the triangular pulse loads induce gentler transient impacts under the impact of triangular wave and rectangular wave pulse loads with the same energy. The maximum fluctuation rates of the compressor outlet pressure, combustor outlet temperature, turbine speed, and DC bus voltage caused by triangular wave pulse loads were reduced by 0.33 %, 1.81 %, 0.14 %, and 1.31 %, respectively, compared to the rectangular wave pulse loads. Significant reductions are observed in the maximum fluctuation rates of key parameters under a six-pulse triangular wave pulse load with a peak power of 70 kW when the flywheel energy storage system is integrated into the gas turbine generator system. Specifically, compared to the scenario without the flywheel energy storage system, the maximum fluctuation rates of compressor outlet pressure, combustor outlet temperature, turbine speed, and DC bus voltage are reduced by 3.11 %, 8.15 %, 0.73 %, and 3.51 %, respectively. This work provides critical insights for optimizing gas turbine control strategies in marine power systems under pulsed loads, highlighting the synergy between thermal inertia management and the dynamic characteristics of flywheel energy storage system.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127339"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Estimation of local composition in zeotropic mixtures and its application to heat pump system modeling","authors":"Yeonwoo Jeong , Sangwook Lee , Min Soo Kim","doi":"10.1016/j.applthermaleng.2025.127345","DOIUrl":"10.1016/j.applthermaleng.2025.127345","url":null,"abstract":"<div><div>Refrigerant mixtures have been proposed as alternatives to traditional refrigerants to meet environmental regulations while offering favorable thermodynamic properties. When zeotropic mixtures are utilized in heat pump systems, local composition shift arises from differences in velocity and composition between the liquid and vapor phases in the two-phase region. This phenomenon leads to off-design operation, as the local composition varies along the system, deviating from the initial charge composition. Therefore, it is necessary to consider local composition shift when designing heat pump systems with refrigerant mixtures. In this study, local compositions of mixtures are numerically estimated throughout a heat pump system, and a system model is suggested reflecting these composition shifts. The estimation results indicate good agreement with the experimental data, with maximum root mean squared error (RMSE) of 1.46% for local compositions of R32/R1234yf mixtures. Furthermore, two system models, one considering and one not considering local composition shift, are compared under various operating conditions. The model with composition shift shows improved accuracy, decreasing the mean absolute percentage error (MAPE) of system parameters by up to 5.52%p. Based on this model, the effect of local composition shift on the system is analyzed. Simulation results reveal that composition shift leads to capacity reductions of 3.7% and 7.4% in cooling and heating modes, respectively, under standard conditions of this study.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"278 ","pages":"Article 127345"},"PeriodicalIF":6.1,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}