Thetechnical,economic,and environmental performance of solar hot-water(SWH)systems for Swedish residential apartments—where approximately 80%of household energy is devoted to space heating and sanitary hotwater produ...Thetechnical,economic,and environmental performance of solar hot-water(SWH)systems for Swedish residential apartments—where approximately 80%of household energy is devoted to space heating and sanitary hotwater production—was assessed.Two collector types,flat plate(FP)and evacuated tube(ET),were simulated in TSOL Pro 5.5 for five major cities(Stockholm,Goteborg,Malmo,Uppsala,Linkoping).Climatic data and cold-water temperatures were sourced fromMeteonorm7.1,and economic parameters were derived fromrecent national statistics and literature.All calculations explicitly accounted for heat losses from collectors,storage tanks,and internal and external piping systems,and established solar-fraction equations and NPV methodology were applied.Sensitivity analyseswere conducted to determine optimal collector area and hot-water storage volume.Additionally,a Monte Carlo uncertainty analysis(10,000 iterations,±10%)and break-even subsidy/carbon-credit assessments were performed.The discount rate for NPV calculations was set at 0% for capital interest with a 5%reinvestment return over a 25-year lifespan.The highest annual solar heat yield(8017.5 kWh)was obtained in Malmo with 32 m^(2) of ET collectors,meeting 52.7%of total heating demand.Annual CO_(2) emissions were avoided by FP and ET systems by approximately~9.07 and~10.55 tonnes,respectively.Economic analysis showed that no payback was achieved without government allowance;however,at a$0.05/m^(2) allowance,positive NPV was exhibited at all stations.Lower levelized heat costs were delivered by FP systems,while ET systems demonstrated consistent superiority under climatic and economic variability according to the Monte Carlo analysis.Optimal design parameters were identified as 32 collectors and a 1680 L heating buffer tank,and Sankey diagrams highlighted collector losses as the dominant inefficiency.It was concluded that properly designed SWH systems,when supported by targeted subsidies,can significantly reduce fossil-fuel demand and CO_(2) emissions in Swedish residential buildings.This work provides the first city-specific technical–economic–environmental dataset for Sweden,establishes a foundation for a national solar-heating atlas,and informs policymaking toward 100%renewable energy targets;beyond the baseline evaluation,explicit subsidy and carbon-price thresholds,quantified uncertainty ranges,and loss-flow visualizations are also provided,reinforcing the robustness and policy relevance of the findings.展开更多
This study presents the design,construction,and thermal evaluation of a solar-powered cocoa roaster based on a Parabolic Cylinder Collector(PCC)with dual-axis solar tracking.The system integrates three functional subs...This study presents the design,construction,and thermal evaluation of a solar-powered cocoa roaster based on a Parabolic Cylinder Collector(PCC)with dual-axis solar tracking.The system integrates three functional subsystems:the cylindrical-parabolic reflecting surface,the stainless-steel absorber tube,and a microcontrollerbased tracking mechanism.The prototype enables continuous acquisition of key thermal variables(solar irradiance,ambient temperature,absorber surface temperature,and bean temperature),allowing a detailed characterization of heat transfer processes during roasting.Roasting experiments were conducted at controlled durations of 40,55,and 70 min between 10:00 and 14:00 h.Maximum roasting temperatures of 125℃–137℃ were reached under average irradiance levels of 685.7–930.5 W m−2.The lowest final moisture content was 2.19%,within the recommended range for high-quality cocoa.Longer roasting durations promoted thermal energy accumulation within the absorber tube,enhancing convective and radiative heat transfer to the bean mass even under fluctuating irradiance.The experimental trends reveal a strong coupling between irradiance variability,absorber temperature,and internal air-beam heat transfer.Comparison with reference parabolic trough collector studies indicate that,although the process-level roasting efficiency(3.83%–7.45%)is lower than conventional collector-level thermal efficiencies,the operating temperatures and moisture-reduction rates align with the thermal requirements of food-processing systems rather than high-enthalpy solar applications.These results also demonstrate the potential of coupling PCC-based solar concentration with lowtemperature convective–radiative roasting processes.Overall,the findings confirm the feasibility of implementing PCC-based roasting technologies in rural or off-grid regions,where solar-driven heat transfer offers a sustainable,low-cost alternative to fossil-fuel-based roasting systems,enabling a controlled thermophysical environment for cocoa transformation.展开更多
针对定日镜风致振动会降低光热电站发电效率的问题,开发一款基于深度强化学习的控制算法抑制定日镜振动。首先构建吸振器-定日镜动力学模型的Open AI Gym训练环境,完成模拟状态下深度强化学习模型的训练并验证随机振动控制效果。其次搭...针对定日镜风致振动会降低光热电站发电效率的问题,开发一款基于深度强化学习的控制算法抑制定日镜振动。首先构建吸振器-定日镜动力学模型的Open AI Gym训练环境,完成模拟状态下深度强化学习模型的训练并验证随机振动控制效果。其次搭建实验系统,通过构建包含定日镜振动特征、控制信号、奖励值与终止状态的数据集,训练智能体学习吸振器的电-磁-刚度机理。最后编写模型调用脚本,在LabVIEW主系统调用函数节点完成混合编程。结果显示在12.3 Hz的外界激励下,该算法可在1 s内计算出最优的控制信号,将±0.42 m/s^(2)的振幅降低到±0.29 m/s^(2)。该算法利用神经网络实现定日镜振动的跟踪控制,对强化学习算法落地及定日镜结构保护有一定参考意义。展开更多
文摘Thetechnical,economic,and environmental performance of solar hot-water(SWH)systems for Swedish residential apartments—where approximately 80%of household energy is devoted to space heating and sanitary hotwater production—was assessed.Two collector types,flat plate(FP)and evacuated tube(ET),were simulated in TSOL Pro 5.5 for five major cities(Stockholm,Goteborg,Malmo,Uppsala,Linkoping).Climatic data and cold-water temperatures were sourced fromMeteonorm7.1,and economic parameters were derived fromrecent national statistics and literature.All calculations explicitly accounted for heat losses from collectors,storage tanks,and internal and external piping systems,and established solar-fraction equations and NPV methodology were applied.Sensitivity analyseswere conducted to determine optimal collector area and hot-water storage volume.Additionally,a Monte Carlo uncertainty analysis(10,000 iterations,±10%)and break-even subsidy/carbon-credit assessments were performed.The discount rate for NPV calculations was set at 0% for capital interest with a 5%reinvestment return over a 25-year lifespan.The highest annual solar heat yield(8017.5 kWh)was obtained in Malmo with 32 m^(2) of ET collectors,meeting 52.7%of total heating demand.Annual CO_(2) emissions were avoided by FP and ET systems by approximately~9.07 and~10.55 tonnes,respectively.Economic analysis showed that no payback was achieved without government allowance;however,at a$0.05/m^(2) allowance,positive NPV was exhibited at all stations.Lower levelized heat costs were delivered by FP systems,while ET systems demonstrated consistent superiority under climatic and economic variability according to the Monte Carlo analysis.Optimal design parameters were identified as 32 collectors and a 1680 L heating buffer tank,and Sankey diagrams highlighted collector losses as the dominant inefficiency.It was concluded that properly designed SWH systems,when supported by targeted subsidies,can significantly reduce fossil-fuel demand and CO_(2) emissions in Swedish residential buildings.This work provides the first city-specific technical–economic–environmental dataset for Sweden,establishes a foundation for a national solar-heating atlas,and informs policymaking toward 100%renewable energy targets;beyond the baseline evaluation,explicit subsidy and carbon-price thresholds,quantified uncertainty ranges,and loss-flow visualizations are also provided,reinforcing the robustness and policy relevance of the findings.
基金the Program for Teaching Development(PRODEP)for funding the project UJAT-PTC-251(Development and Evaluation of a Cocoa Roaster in the Tabasco Region).
文摘This study presents the design,construction,and thermal evaluation of a solar-powered cocoa roaster based on a Parabolic Cylinder Collector(PCC)with dual-axis solar tracking.The system integrates three functional subsystems:the cylindrical-parabolic reflecting surface,the stainless-steel absorber tube,and a microcontrollerbased tracking mechanism.The prototype enables continuous acquisition of key thermal variables(solar irradiance,ambient temperature,absorber surface temperature,and bean temperature),allowing a detailed characterization of heat transfer processes during roasting.Roasting experiments were conducted at controlled durations of 40,55,and 70 min between 10:00 and 14:00 h.Maximum roasting temperatures of 125℃–137℃ were reached under average irradiance levels of 685.7–930.5 W m−2.The lowest final moisture content was 2.19%,within the recommended range for high-quality cocoa.Longer roasting durations promoted thermal energy accumulation within the absorber tube,enhancing convective and radiative heat transfer to the bean mass even under fluctuating irradiance.The experimental trends reveal a strong coupling between irradiance variability,absorber temperature,and internal air-beam heat transfer.Comparison with reference parabolic trough collector studies indicate that,although the process-level roasting efficiency(3.83%–7.45%)is lower than conventional collector-level thermal efficiencies,the operating temperatures and moisture-reduction rates align with the thermal requirements of food-processing systems rather than high-enthalpy solar applications.These results also demonstrate the potential of coupling PCC-based solar concentration with lowtemperature convective–radiative roasting processes.Overall,the findings confirm the feasibility of implementing PCC-based roasting technologies in rural or off-grid regions,where solar-driven heat transfer offers a sustainable,low-cost alternative to fossil-fuel-based roasting systems,enabling a controlled thermophysical environment for cocoa transformation.
