A district heating and hot water supply system is presented which synthetically utilizes geothermal energy,solar thermal energy and natural gas thermal energy.The multi-energy utilization system has been set at the ne...A district heating and hot water supply system is presented which synthetically utilizes geothermal energy,solar thermal energy and natural gas thermal energy.The multi-energy utilization system has been set at the new campus of Tianjin Polytechnic University(TPU),A couple of deep geothermal wells which are 2 300 m in depth were dug,Deep geothermal energy cascade utilization is achieved by two stages of plate heat exchangers(PHE) and two stages of water source heat pumps(WSHP).Shallow geothermal energy is used in assistant heating by two ground coupled heat pumps(GCHPs) with 580 vertical ground wells which are 120 m in depth.Solar thermal energy collected by vacuum tube arrays(VTAs) and geothermal energy are complementarily utilized to make domestic hot water.Superfluous solar energy can be stored in shallow soil for the GCHP utilization.The system can use fossil fuel thermal energy by two natural gas boilers(NGB) to assist in heating and making hot water.The heating energy efficiency was measured in the winter of 2010-2011.The coefficients of performance(COP) under different heating conditions are discussed.The performance of hot water production is tested in a local typical winter day and the solar thermal energy utilization factor is presented.The rusults show that the average system COP is 5.75 or 4.96 under different working conditions,and the typical solar energy utilization factor is 0.324.展开更多
The large-scale application of renewable energy is an important strategy to achieve the goal of carbon neutrality in the building sector.Energy flexibility is essential for ensuring balance between energy demand and s...The large-scale application of renewable energy is an important strategy to achieve the goal of carbon neutrality in the building sector.Energy flexibility is essential for ensuring balance between energy demand and supply when targeting the maximum penetration rate of renewable energy during the operation of regional integrated energy systems.Revealing the energy flexibility characteristics of centralized hot water systems,which are an important source of such flexibility,is of great significance to the optimal operation of regional integrated energy systems.Hence,in this study,based on the annual real-time monitoring data,the energy flexibility of the centralized hot water system in university dormitories is evaluated from the perspective of available storage capacity(C_(ADR)),recovery time(t_(recovery)),and storage efficiency(η_(ADR)),by the data-driven simulation method.The factors influencing the energy flexibility of the centralized hot water system are also analyzed.Available storage capacity has a strong positive correlation with daily water consumption and a strong negative correlation with daily mean outdoor temperature.These associations indicate that increased water use on the energy flexibility of the centralized hot water system is conducive to optimal dispatching.In contrast,higher outdoor temperature is unfavorable.The hourly mean value of the available storage capacity in spring and winter is found to be around 80 kWh in the daytime,and about twice that in summer and autumn.Recovery time is evenly distributed throughout the year,while t_(recovery)/C_(ADR)in spring and winter is about half that in summer.The storage efficiency was significantly higher in spring,summer,and winter than in autumn.The hourly mean storage efficiency was found to be about 40%in the daytime.The benefits of activating energy flexibility in spring and winter are the best,because these two seasons have higher available storage capacity and storage efficiency,while the benefit of activating energy flexibility is the highest at 6:00 a.m.,and very low from midnight to 3:00 a.m.展开更多
太阳能-空气源热泵热水系统(solar-air source heat pump hot water system, SAHWS)常用于宿舍楼宇供暖,通过对系统参数的优化设计可显著提高系统能效性能与环境友好性。为得到一种综合考虑SAHWS经济、能源、环保与节能的优化方法,提出...太阳能-空气源热泵热水系统(solar-air source heat pump hot water system, SAHWS)常用于宿舍楼宇供暖,通过对系统参数的优化设计可显著提高系统能效性能与环境友好性。为得到一种综合考虑SAHWS经济、能源、环保与节能的优化方法,提出了一种新型组合优化设计策略,并利用TRNSYS软件搭建系统仿真模型,以西安、西宁、拉萨这3座不同太阳能资源等级城市为例,对SAHWS运行工况对比分析。结果表明:与常用生命周期成本设计相比,所提出的组合优化设计不仅降低了系统成本,还有着较低的系统能耗;组合优化设计的热泵能耗与工作小时数最短,且有最低的热损,在投资成本、系统季节性能因子、太阳能保证率以及碳粉尘、二氧化碳排放量均有较好表现。展开更多
The presence or absence of occupants in a building has a direct effect on its energy use,as it influences the operation of various building energy systems.Buildings with high occupancy variability,such as universities...The presence or absence of occupants in a building has a direct effect on its energy use,as it influences the operation of various building energy systems.Buildings with high occupancy variability,such as universities,where fluctuations occur throughout the day and across the year,can pose challenges in developing control strategies that aim to balance comfort and energy efficiency.This situation becomes even more complex when such buildings are integrated with renewable energy technologies,due to the inherently intermittent nature of these energy source.To promote widespread integration of renewable energy sources in such buildings,the adoption of advanced control strategies such as model predictive control(MPC)is imperative.However,the variable nature of occupancy patterns must be considered in its design.In response to this,the present study evaluates a price responsive MPC strategy for a solar thermal heating system integrated with thermal energy storage(TES)for buildings with high occupancy variability.The coupled system supplies the building heating through a low temperature underfloor heating system.A case study University building in Nottingham,UK was employed for evaluating the feasibility of the proposed heating system controlled by MPC strategy.The MPC controller aims to optimize the solar heating system’s operation by dynamically adjusting to forecasted weather,occupancy,and solar availability,balancing indoor comfort with energy efficiency.By effectively integrating with thermal energy storage,it maximizes solar energy utilization,reducing reliance on non-renewable sources and ultimately lowering energy costs.The developed model has undergone verification and validation process,utilizing both numerical simulations and experimental data.The result shows that the solar hot water system provided 63%heating energy in total for the case study classroom and saved more than half of the electricity cost compared with that of the original building heating system.The electricity cost saving has been confirmed resulting from the energy shifting from high price periods to medium to low price periods through both active and passive heating energy storages.展开更多
The feasibility of employing stand-alone solar energy systems to meet demand-side loads depends strongly on providing appropriate solar energy storage. The present paper presents an efficient and economical, undergrou...The feasibility of employing stand-alone solar energy systems to meet demand-side loads depends strongly on providing appropriate solar energy storage. The present paper presents an efficient and economical, underground, thermal storage design to store hot water at a temperature of around 180?C required for running a double effect absorption chiller to cool a zero-energy-house in a desert environment. The performance of the design is evaluated employing a specially developed efficient mathematical model, for simulating the steady state radiation, convection and conduction processes occurring within the storage unit. The model is presented and analyzed, and employed to investigate the effects of various design parameters on storage efficiency. It is demonstrated that high storage efficiency may be reached, providing that appropriate insulation materials are used. It is also revealed that the soil conductivity has little effect on storage efficiency.展开更多
直膨式太阳能光伏光热(photovoltaic-thermal,PVT)热泵是一种综合利用太阳能资源的新型高效技术。为探究不同环境条件以及系统配置方式对直膨式太阳能PVT热泵热水系统运行性能的影响,基于能量平衡原理在Matlab平台上建立了系统的仿真模...直膨式太阳能光伏光热(photovoltaic-thermal,PVT)热泵是一种综合利用太阳能资源的新型高效技术。为探究不同环境条件以及系统配置方式对直膨式太阳能PVT热泵热水系统运行性能的影响,基于能量平衡原理在Matlab平台上建立了系统的仿真模型,基于临港地区的环境数据,分析了各季节典型日下不同配置系统的热水供应性能以及发电增益的全年波动情况。结果表明,随压缩机理论输气量的减小,热水系统的性能系数(coefficient of performance,COP)有所提高,但所需的加热时间增加,系统的全年发电增益随理论输气量的减小而减小。展开更多
基金Project(2010DFA72740-06) supported by International Science & Technology Cooperation Program of China
文摘A district heating and hot water supply system is presented which synthetically utilizes geothermal energy,solar thermal energy and natural gas thermal energy.The multi-energy utilization system has been set at the new campus of Tianjin Polytechnic University(TPU),A couple of deep geothermal wells which are 2 300 m in depth were dug,Deep geothermal energy cascade utilization is achieved by two stages of plate heat exchangers(PHE) and two stages of water source heat pumps(WSHP).Shallow geothermal energy is used in assistant heating by two ground coupled heat pumps(GCHPs) with 580 vertical ground wells which are 120 m in depth.Solar thermal energy collected by vacuum tube arrays(VTAs) and geothermal energy are complementarily utilized to make domestic hot water.Superfluous solar energy can be stored in shallow soil for the GCHP utilization.The system can use fossil fuel thermal energy by two natural gas boilers(NGB) to assist in heating and making hot water.The heating energy efficiency was measured in the winter of 2010-2011.The coefficients of performance(COP) under different heating conditions are discussed.The performance of hot water production is tested in a local typical winter day and the solar thermal energy utilization factor is presented.The rusults show that the average system COP is 5.75 or 4.96 under different working conditions,and the typical solar energy utilization factor is 0.324.
基金This work was funded by the Center for Balance Architecture of Zhejiang University under the project:K Transversal 20203512-24CThis study was also partially supported by the Ningbo Science and Technology Bureau(No.2021S141).
文摘The large-scale application of renewable energy is an important strategy to achieve the goal of carbon neutrality in the building sector.Energy flexibility is essential for ensuring balance between energy demand and supply when targeting the maximum penetration rate of renewable energy during the operation of regional integrated energy systems.Revealing the energy flexibility characteristics of centralized hot water systems,which are an important source of such flexibility,is of great significance to the optimal operation of regional integrated energy systems.Hence,in this study,based on the annual real-time monitoring data,the energy flexibility of the centralized hot water system in university dormitories is evaluated from the perspective of available storage capacity(C_(ADR)),recovery time(t_(recovery)),and storage efficiency(η_(ADR)),by the data-driven simulation method.The factors influencing the energy flexibility of the centralized hot water system are also analyzed.Available storage capacity has a strong positive correlation with daily water consumption and a strong negative correlation with daily mean outdoor temperature.These associations indicate that increased water use on the energy flexibility of the centralized hot water system is conducive to optimal dispatching.In contrast,higher outdoor temperature is unfavorable.The hourly mean value of the available storage capacity in spring and winter is found to be around 80 kWh in the daytime,and about twice that in summer and autumn.Recovery time is evenly distributed throughout the year,while t_(recovery)/C_(ADR)in spring and winter is about half that in summer.The storage efficiency was significantly higher in spring,summer,and winter than in autumn.The hourly mean storage efficiency was found to be about 40%in the daytime.The benefits of activating energy flexibility in spring and winter are the best,because these two seasons have higher available storage capacity and storage efficiency,while the benefit of activating energy flexibility is the highest at 6:00 a.m.,and very low from midnight to 3:00 a.m.
文摘太阳能-空气源热泵热水系统(solar-air source heat pump hot water system, SAHWS)常用于宿舍楼宇供暖,通过对系统参数的优化设计可显著提高系统能效性能与环境友好性。为得到一种综合考虑SAHWS经济、能源、环保与节能的优化方法,提出了一种新型组合优化设计策略,并利用TRNSYS软件搭建系统仿真模型,以西安、西宁、拉萨这3座不同太阳能资源等级城市为例,对SAHWS运行工况对比分析。结果表明:与常用生命周期成本设计相比,所提出的组合优化设计不仅降低了系统成本,还有着较低的系统能耗;组合优化设计的热泵能耗与工作小时数最短,且有最低的热损,在投资成本、系统季节性能因子、太阳能保证率以及碳粉尘、二氧化碳排放量均有较好表现。
文摘The presence or absence of occupants in a building has a direct effect on its energy use,as it influences the operation of various building energy systems.Buildings with high occupancy variability,such as universities,where fluctuations occur throughout the day and across the year,can pose challenges in developing control strategies that aim to balance comfort and energy efficiency.This situation becomes even more complex when such buildings are integrated with renewable energy technologies,due to the inherently intermittent nature of these energy source.To promote widespread integration of renewable energy sources in such buildings,the adoption of advanced control strategies such as model predictive control(MPC)is imperative.However,the variable nature of occupancy patterns must be considered in its design.In response to this,the present study evaluates a price responsive MPC strategy for a solar thermal heating system integrated with thermal energy storage(TES)for buildings with high occupancy variability.The coupled system supplies the building heating through a low temperature underfloor heating system.A case study University building in Nottingham,UK was employed for evaluating the feasibility of the proposed heating system controlled by MPC strategy.The MPC controller aims to optimize the solar heating system’s operation by dynamically adjusting to forecasted weather,occupancy,and solar availability,balancing indoor comfort with energy efficiency.By effectively integrating with thermal energy storage,it maximizes solar energy utilization,reducing reliance on non-renewable sources and ultimately lowering energy costs.The developed model has undergone verification and validation process,utilizing both numerical simulations and experimental data.The result shows that the solar hot water system provided 63%heating energy in total for the case study classroom and saved more than half of the electricity cost compared with that of the original building heating system.The electricity cost saving has been confirmed resulting from the energy shifting from high price periods to medium to low price periods through both active and passive heating energy storages.
文摘The feasibility of employing stand-alone solar energy systems to meet demand-side loads depends strongly on providing appropriate solar energy storage. The present paper presents an efficient and economical, underground, thermal storage design to store hot water at a temperature of around 180?C required for running a double effect absorption chiller to cool a zero-energy-house in a desert environment. The performance of the design is evaluated employing a specially developed efficient mathematical model, for simulating the steady state radiation, convection and conduction processes occurring within the storage unit. The model is presented and analyzed, and employed to investigate the effects of various design parameters on storage efficiency. It is demonstrated that high storage efficiency may be reached, providing that appropriate insulation materials are used. It is also revealed that the soil conductivity has little effect on storage efficiency.
文摘直膨式太阳能光伏光热(photovoltaic-thermal,PVT)热泵是一种综合利用太阳能资源的新型高效技术。为探究不同环境条件以及系统配置方式对直膨式太阳能PVT热泵热水系统运行性能的影响,基于能量平衡原理在Matlab平台上建立了系统的仿真模型,基于临港地区的环境数据,分析了各季节典型日下不同配置系统的热水供应性能以及发电增益的全年波动情况。结果表明,随压缩机理论输气量的减小,热水系统的性能系数(coefficient of performance,COP)有所提高,但所需的加热时间增加,系统的全年发电增益随理论输气量的减小而减小。
