Energy Conversion and Management最新文献

{"title":"Sustainable hydrogen production through catalytic pyrolysis of lignocellulosic biomass using carbon dioxide","authors":"Hoyeon Cha ,&nbsp;Youkwan Kim ,&nbsp;Taewoo Lee ,&nbsp;Seong-Jik Park ,&nbsp;Eilhann E. Kwon","doi":"10.1016/j.enconman.2025.120564","DOIUrl":"10.1016/j.enconman.2025.120564","url":null,"abstract":"<div><div>Although hydrogen is recognized a carbon-free fuel, its production face environmental challenges in carbon dioxide emissions due to energy-intensive processes. To pursue more sustainable hydrogen production, this study integrates carbon dioxide-cofed catalytic pyrolysis of lignocellulosic biomass, especially perilla straw, with the water-gas shift reaction. The introduction of carbon dioxide into the pyrolysis process enhances syngas production per unit mass of perilla straw, while mitigating process-related carbon dioxide emissions. At temperatures above 460 °C, carbon dioxide participated in partial oxidation of volatiles stemming from perilla straw, leading to its reduction into carbon monoxide. To investigate this genuine reaction feature associated with carbon dioxide, the pyrolysis system was modified with an additional heat supply in the presence of cobalt-, iron-, or nickel-based catalysts. Catalytic pyrolysis facilitated further thermal cracking of the volatiles into smaller molecules, thereby accelerating carbon dioxide reactivity under enhanced mass transfer. These mechanisms related to carbon dioxide selectively promoted the formation of carbon monoxide. The resulting carbon monoxide-rich syngas was subsequently fed into the water-gas shift reaction, where carbon monoxide reacted with steam to stoichiometrically produce hydrogen and carbon dioxide. Thus, this study suggests the potential of carbon dioxide-cofed catalytic pyrolysis of perilla straw as an effective approach for enhancing hydrogen production while achieving process-related carbon dioxide reduction.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120564"},"PeriodicalIF":10.9,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation-based thermodynamic analysis of hydrogen liquefaction processes: Design implications and limitations","authors":"Amjad Riaz ,&nbsp;Ahmad Naquash ,&nbsp;Muhammad Abdul Qyyum","doi":"10.1016/j.enconman.2025.120542","DOIUrl":"10.1016/j.enconman.2025.120542","url":null,"abstract":"<div><div>This study evaluates hydrogen (H₂) liquefaction systems using several thermodynamic models to better understand how property predictions affect process performance. Simulations were conducted in Aspen HYSYS® and Aspen Plus® using four equations of state: Peng-Robinson (PR), Soave-Redlich-Kwong (SRK), Modified Benedict-Webb-Rubin (MBWR), and RefProp (RF). The analysis focused on key parameters such as enthalpy, entropy, exergy, and heat capacity across cryogenic temperatures. Results show that model selection significantly impacts energy efficiency and heat integration. Additionally, the risk of refrigerant freezing at extremely low temperatures is evaluated, which can cause operational issues, and the most stable compositions are identified. The analysis of heat exchanger behavior shows that variations in fluid properties can change energy recovery by up to 45%. Results reveal that MBWR and RF models provide more accurate predictions in cryogenic conditions, thereby may potentially improve process efficiency by approximately 20% compared to other models. The findings underscore the criticality of accurate thermodynamic modeling in designing efficient and commercially viable liquid H₂ production processes.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120542"},"PeriodicalIF":10.9,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal scheduling of micro combined heat and power units: Impact of degradation costs","authors":"Parinaz Aliasghari ,&nbsp;Mohammad Ali Motamad ,&nbsp;Ruud Egging-Bratseth ,&nbsp;Magnus Stålhane","doi":"10.1016/j.enconman.2025.120522","DOIUrl":"10.1016/j.enconman.2025.120522","url":null,"abstract":"<div><div>Increasing uncertainty and intermittency in the energy grid require greater flexibility. Micro-combined heat and power (micro-CHP) systems enhance flexibility by generating both heat and electricity while also supporting grid stability. However, frequent cycling and varying operational conditions may accelerate component degradation, which can affect both the lifetime and economic performance of such systems. This paper presents a cost-minimizing dispatch model for micro-CHP units based on micro gas turbines, which incorporates a more detailed degradation cost model compared to existing approaches. The proposed degradation model accounts for both operational degradation, driven by turbine blade temperature and rotational speed, and degradation caused by startup and shutdown cycles, including damage during critical speed transitions. A case study of a building complex in Germany is used to test the model under different operating conditions. The results show that including degradation costs leads to dispatch schedules with 12% lower total costs over one year, and up to 50% lower costs in some weeks. The results further show that it is not economically beneficial to overload the micro-CHP unit, even for short periods of high demand, as the additional degradation would offset any potential savings in the short term.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120522"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact on greenhouse gas emissions in the ammonia production process by reusing heat in the CO2 absorption stage","authors":"Maurício Oliveira Alves,&nbsp;Luiz Mário Nelson de Goes,&nbsp;George Simonelli","doi":"10.1016/j.enconman.2025.120534","DOIUrl":"10.1016/j.enconman.2025.120534","url":null,"abstract":"<div><div>Ammonia production is one of the largest contributors to greenhouse gas emissions in the chemical industry, generating 2.4 tonnes of CO₂ per tonne of product and requiring an energy intensity of 46 GJ/t (IEA-2021). In 2020, 50% of the natural gas and 44% of the coal used by the global chemical industry went to the ammonia chain (IEA-2021). The hydrogen used in the synthesis of ammonia must be purified to remove the CO₂ generated during the steam reforming process of natural gas or coal gasification. This work focuses on the gaseous absorption of CO₂ to reduce the absorption temperature and the heat required for the regeneration of the absorbent solution. Using simulations in HYSYS® and experimental design, the potential for reducing energy consumption and heat recovery was evaluated, aiming to remove more than 90% of the CO₂. The results demonstrated CO₂ removal efficiencies between 85% and 99%, with a heat recovery potential equivalent to 2.32 GJ per tonne of ammonia produced. Such energy recovery corresponds to a 5% reduction in the energy intensity of ammonia production, compared to data from the International Energy Agency (IEA-2021). These results reveal an opportunity for more sustainable processes in the global ammonia industry.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120534"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transient computational fluid dynamics analysis of solidification in molten salt air-cooled heat exchangers","authors":"Arun K. Raj,&nbsp;Nishith B. Desai,&nbsp;Rohit Kothari,&nbsp;Fredrik Haglind","doi":"10.1016/j.enconman.2025.120539","DOIUrl":"10.1016/j.enconman.2025.120539","url":null,"abstract":"<div><div>Molten salts are ideal for high-temperature applications, including pumped thermal energy storage, molten salt reactors, and industrial processes requiring continuous high-temperature operation and energy recovery. Compared to thermal oils, molten salt gas-cooled heat exchangers offer superior performance in high-temperature applications, thereby enhancing plant efficiency. However, cyclic operation of the heat exchanger may result in local salt solidification caused by rapid thermal excursions, which can pose technical and operational issues. This paper presents a numerical analysis of localized solidification within an air-cooled heat exchanger utilizing molten salt, employing a three-dimensional, pressure-based Newtonian solver coupled with a realizable <span><math><mrow><mi>k</mi><mo>-</mo><mi>ε</mi></mrow></math></span> turbulence model and an enthalpy-porosity approach. The operational limits of the working fluid (air) that trigger solidification within the molten salt air-cooled heat exchanger tube bundle are established. A two-step method, involving steady-state and transient analyses, is employed to evaluate the effect of air inlet temperature, pressure, air velocity, and initial molten salt temperatures on the air outlet temperature, overall heat transfer coefficient, and effectiveness. Subsequently, based on the results of the transient analysis, the onset of localized salt solidification is identified. The results of the steady-state analysis suggest that changes in air pressure and velocity significantly impact the effectiveness and likelihood of salt solidification, more so than do variations in inlet air and initial salt temperatures. The onset of salt solidification is accelerated at high air velocity (&gt;2.0 m/s) and pressure (&gt;50 bar) when both the inlet air and initial salt temperatures are at their lowest values, 473 K and 673 K, respectively. Furthermore, the results indicate that the upper tubes near to the nozzle inlet are particularly prone to solidification. Overall, the results serve as a benchmark for the modelling of salt solidification in heat exchangers, as well as supporting the design and optimization of freezing protection strategies for molten salt heat exchangers, resulting in effective and dependable systems for high-temperature applications.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120539"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CO2 capture combined with H2 and CH4 purification via a membrane plant: Process design, energy integration and economic analysis","authors":"Pasquale Francesco Zito,&nbsp;Adolfo Iulianelli","doi":"10.1016/j.enconman.2025.120538","DOIUrl":"10.1016/j.enconman.2025.120538","url":null,"abstract":"<div><div>CO₂ capture paired with H₂ and CH₄ recovery from a ternary mixture is studied in this work, with the prospect of finding new solutions able to limit the greenhouse gas emissions, meanwhile proposing a theoretical evaluation of the economic benefits and drawbacks of a membrane gas separation process adoptable for the aforementioned purpose. A simulated plant consisting of three membrane units (i.e., one Pd-based followed by two SAPO-34) allows obtaining pure streams of H₂ (about 99.999 %), CH₄ and CO₂ (about 96 %) with recovery values higher than 90 %. This solution is found to be versatile, since all the components show high purity and recovery at different feed composition.</div><div>The preliminary economic analysis, performed to evaluate whether the process can be profitable, is carried out varying the feed flow rate (from 10 to 100 kmol/h), feed material price and labour cost. The biggest plant fed with 100 kmol/h is the most profitable, showing an economic potential more than ten times greater compared to that fed with 10 kmol/h. Compression provides a significant cost (about 72 % of total equipment and utility costs), followed by heat exchange (about 17 %), whereas membranes represent only 11 % of the expenses. Considering the total costs of the simulated plant, raw material has a very high impact, whereas membrane cost can be neglected. The present investigation also reveals that this solution is convenient in a wide range of feed material price and labour cost. For a fixed feed gas price of 0.10 $/Nm³, a net profit of about 940·10³ $/y can be achieved, whereas net present value after 10 years approaches 3900·10³ $.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120538"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High energy density long-term thermochemical energy storage composite based on salt and wood-derived activated biochar","authors":"Ali Kasebi Vayghan,&nbsp;Maryam Roza Yazdani McCord,&nbsp;Annukka Santasalo-Aarnio,&nbsp;Ari Seppälä","doi":"10.1016/j.enconman.2025.120532","DOIUrl":"10.1016/j.enconman.2025.120532","url":null,"abstract":"<div><div>Hygroscopic salts as thermochemical energy storage materials stand out for their substantial energy storage density and long-term storage capability, but challenges like agglomeration, deliquescence, and mass transfer issues during sorption hinder their practical application. To resolve these problems, a nature-inspired, sustainable, and inexpensive composite composed of a wood-derived porous activated biochar matrix and CaCl₂ as active component is developed through an impregnation method. This study investigates how matrix particle size affects the energy storage density and cyclic stability of the composite. In addition, this research analyzes the salt leakage and evaluates the stability of the composite by using an accurate quantitative method. A simultaneous thermal analyzer coupled with a humidifier was used to analyze the energy storage density. Scanning electron microscopy and X-ray micro-computed tomography were used to analyze salt deposition on the outer surface and inner porous structure of the matrices. The surface area and porosity of the matrix and composite samples were characterized by analyzing nitrogen adsorption/desorption isotherms. Derived from cellular and vascular channels of wood, the activated biochar matrix shows a multi-scale porous structure that not only has exceptional surface area but also facilitates mass transfer as well as successful salt impregnation. A particle diameter between 354 to 595 µm leads to synthesis of the composite with optimal performance, exhibiting an initial energy storage density of approximately 2480 J/g. The energy storage density of this composite remains stable at 2310 J/g and 1780 J/g after 10 consecutive hydration/dehydration and 5 leakage test cycles respectively.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120532"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermo-economic evaluation of working fluids for a flue gas driven organic Rankine cycle powered vapor compression cycle for cooling air conditioning using a two-step intermediate performance index","authors":"Muhammad Talha ,&nbsp;Muhammad Tauseef Nasir ,&nbsp;Khawaja Fahad Iqbal ,&nbsp;Waqas Khalid ,&nbsp;Muhammad Safdar ,&nbsp;Nawaf Mehmood Malik","doi":"10.1016/j.enconman.2025.120541","DOIUrl":"10.1016/j.enconman.2025.120541","url":null,"abstract":"<div><div>In this study, the thermo-economic evaluation of flue gases driven organic Rankine cycle (ORC) powered vapor compression chiller (VCC) has been conducted. The multi-objective optimization was conducted by first obtaining the Artificial Neural Network (ANN) to obtain the total exergy destruction <span><math><mrow><mo>(</mo><msub><mrow><mi>Ed</mi></mrow><mrow><mi>tot</mi></mrow></msub><mo>)</mo></mrow></math></span> and total heat transfer capacity of all the heat exchanger <span><math><mrow><msub><mrow><mo>(</mo><mi>U</mi><mi>A</mi></mrow><mrow><mi>tot</mi></mrow></msub><mrow><mo>)</mo></mrow></mrow></math></span>. Afterwards, the optimization by applying the Genetic Algorithm (GA) together with Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was carried out. Subsequently, at the optimized point, the operating parameters obtained were used to obtain the ANN regressed equations for the shell and tube type, and flat plate heat exchanger area and pressure drops. The obtained equations were further used to optimize these entities using Genetic Algorithm and the TOPSIS to acquire the total investment costs. This two-step process enables the comprehensive yet computationally manageable multi-objective optimization of the thermal systems of similar nature. From the research conducted, the Decane ORC powered R600a VCC was found to be the feasible candidate with the total exergy destruction and the payback period of 24.50 kW and 7.25 years, respectively.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120541"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145156144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing power generation in steel flag-based flutter energy harvesters","authors":"Dheeraj Tripathi ,&nbsp;Mehdi Ghommem ,&nbsp;Abdessattar Abdelkefi ,&nbsp;Lotfi Romdhane","doi":"10.1016/j.enconman.2025.120490","DOIUrl":"10.1016/j.enconman.2025.120490","url":null,"abstract":"<div><div>This study aims to identify the effective combination of design parameters to maximize the power generation from flexible steel flag-based flutter energy harvesters. Ambient wind energy is captured from self-sustained oscillations beyond the flutter onset speed, wherein bending oscillations of the flag beam are converted into electrical energy through a piezoelectric coupling using macro-fiber composites. The experiments are performed by varying key parameters like piezoelectric active area, external load resistance, flow speed, and flag shape to determine the most effective configuration for power generation. The dynamic response of the piezoelectric flag exhibits a subcritical bifurcation route. The average output power increases gradually with the flow speed. Increasing the active area from 392 mm<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> to 595 mm<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> leads to nearly 20-fold amplification in generated power, whereas a further doubling of the active area yields only a marginal gain. Among multiple piezoelectric flags with active areas between 392–1190 mm<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>, the one with 595 mm<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> performs best with highest power density of 0.588 <span><math><mi>μ</mi></math></span>W/mm<span><math><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup></math></span>, along with the broadest flow regime for energy harvesting. The peak output power is achieved for external load resistances between 0.1 and 0.27 M<span><math><mi>Ω</mi></math></span>. Among the tested flag geometries (triangular, square, trapezoidal, and rectangular), the triangular shape performs best with the lowest flutter speed and highest harvested power. Average output power up to 62–66 <span><math><mi>μ</mi></math></span>W can be achieved within the 6–10 m/s flow speed range from the proposed energy harvester, suitable for operating low-power wireless sensors.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120490"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and numerical simulation analysis of spectrally selective photovoltaic/thermal system with phase change materials","authors":"Kongfu Hu ,&nbsp;Ken Chen ,&nbsp;Siyan Chan ,&nbsp;Zikai Chen ,&nbsp;Yunfei Xu ,&nbsp;Gang Pei","doi":"10.1016/j.enconman.2025.120554","DOIUrl":"10.1016/j.enconman.2025.120554","url":null,"abstract":"<div><div>This study investigates the performance of a novel low-emissivity photovoltaic/thermal system integrated with phase change materials through numerical simulation. The system addresses two key challenges of conventional photovoltaic/thermal systems: heat loss during winter and overheating in summer. The low-emissivity Photovoltaic cell reduces radiative heat loss, while the integrated phase change material regulates the system’s temperature by absorbing excess heat during periods of peak solar radiation and releasing it during cooler intervals. Simulation results demonstrate a 12.4 % enhancement in thermal efficiency during winter, with efficiency increasing from 24.06 % to 27.40 %. In summer, the phase change material reduces PV cell temperature from 77.1 °C to 61.5 °C, improving electrical efficiency by 4.1 %, from 15.48 % to 16.12 %. Parameter analysis indicates that optimizing phase change material thickness, thermal conductivity, and latent heat capacity significantly enhances system performance. The optimal phase transition temperature of the phase change material is identified as 35–40 °C, ensuring balanced performance throughout different seasons. These results highlight the potential of the novel systems to achieve efficient, year-round energy utilization.</div></div>","PeriodicalId":11664,"journal":{"name":"Energy Conversion and Management","volume":"347 ","pages":"Article 120554"},"PeriodicalIF":10.9,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}