Hydrogen is a type of clean energy which has the potential to replace the fossil energy for transportation,domestic and industrial applications.To expand the hydrogen production method and reduce the consumption of fo...Hydrogen is a type of clean energy which has the potential to replace the fossil energy for transportation,domestic and industrial applications.To expand the hydrogen production method and reduce the consumption of fossil energy,technologies of using renewable energy to generate hydrogen have been developed widely.Due to the advantages of widespread distribution and various hydrogen production methods,most of the research or review works focus on the solar and biomass energy hydrogen production systems.To achieve a comprehensive acknowledge on the development state of current renewable energy hydrogen production technology,a review on hydrogen production systems driven by solar,wind,biomass,geothermal,ocean and hydropower energy has been presented.The reaction process,energy efficiency,exergy efficiency,hydrogen production rate,economic and environmental performance of these systems have been evaluated.Based on the analysis of these different systems,the challenge and prospects of them are also analyzed.展开更多
Architects welcome double skin facade(DSF)due to its aesthetic quality.The first DSF structure was intended to prevent cold weather and strong winds.Nowadays,the application of DSF under different climates has been in...Architects welcome double skin facade(DSF)due to its aesthetic quality.The first DSF structure was intended to prevent cold weather and strong winds.Nowadays,the application of DSF under different climates has been investigated in many previous studies.Fiowever,little work had been done on the behaviour of DSF in hot and humid climates.Therefore,this paper aimed to extend the application into this specific climate and Guangzhou was selected as the sample city.Both the climate and the design influence the performance of DSF.In this paper,rather than explore how each design parameter influences the performance,the design was evaluated from an overall aspect.The Designbuilder software was used to build the single skin facade(SSF)and double skin facade base model.Annual HVAC energy consumption for both the two models was calculated and compared.An optimisation process was conducted to figure out what kinds of parameter combination could make the design more energy-saving and thermally comfortable.The results indicated that it was possible to design an energy-saving DSF system applied in hot and humid climates compared with the SSF model.The efficiency of the DSF could be further enhanced with a better parameter combination.The optimised options had some features in common,which could provide some inspirations for the application of DSF in hot and humid climates.展开更多
Switchable multi-layer ethylene tetra-fluoro-ethylene(ETFE)cushion controls the natural light and heat flux passing through the cushion with varying outdoor conditions by dynamically modifying its properties.In this p...Switchable multi-layer ethylene tetra-fluoro-ethylene(ETFE)cushion controls the natural light and heat flux passing through the cushion with varying outdoor conditions by dynamically modifying its properties.In this paper,the switchable ETFE cushions with ink printing of different optical and thermal properties were adopted as the window in a typical office model,and the indoor daylight and energy consumption were simulated by using Grasshopper software.Experimental model was built to validate the numerical model.Five locations representing five climate zones in China were selected to analyze the feasibility of the switchable ETFE cushion in different climates.The hourly indoor daylight and heat gain in a single day revealed the effects of the dynamic mechanism of ETFE cushion in improving indoor natural light and thermal environment.In addition,the annual daylight performance at the working area(1.5 m from the window)was simulated.ETFE cushion with printing of the lowest transmittance(ETFE1)was the optimal option for most cities and window-to-wall ratios,with the percentage of annual useful daylight hours up to 78.6%,except for the cases where the window-to-wall ratio(WWR)was 0.35 in Harbin,Beijing,and Hefei.The distribution of useful daylight hours revealed that ETFE cushions with low,medium,and high printing transmittance were suitable for offices where people work in the front,medium,and back region of the room,respectively.Energy consumption calculation revealed that ETFE1 showed advantages over other windows in most cities except for cities highly dominated by heating.ETFE1 delivered up to 33%of energy saving over a year in Kunming compared with the conventional double glazing but was not superior in cities with high heating and low cooling demands,such as Harbin.展开更多
Building integrated concentrating photovoltaic(BICPV)windows have attracted numerous studies in recent years.However,there is a tradeoff between the light transmittance and power generation efficiency in the design of...Building integrated concentrating photovoltaic(BICPV)windows have attracted numerous studies in recent years.However,there is a tradeoff between the light transmittance and power generation efficiency in the design of BICPV window.In this paper,a smart luminescent solar concentrator(LSC)is introduced as the BICPV window.The proposed smart LSC system features on the combination of fluorescent dyes with thermochromic materials to enhance photoelectric conversion efficiency as well as form a dynamic response mechanism to ambient solar radiation and environmental temperature.In this study,a BICPV smart window system consists of the waveguide doped with organic dye Lumogen F Red-305(BASF)and the thermochromic hydrogel membrane has been developed.The research on analytic design parameters is executed through optical simulation by ray tracing technology along with outdoor comparative experiments.From simulations for a smart LSC of 100 mm×100 mm×3 mm with a bottom-mounted solar cell of 100 mm×10 mm,the optical effective concentration is found to be with the range of 1.23 to 1.31 when a highest gain of 1.26 in power over the bare solar cell is obtained from experiments.展开更多
Ground-coupled heat pumps(GCHP)are commonly used in residential heating system.To mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is developed.The new recharging sys...Ground-coupled heat pumps(GCHP)are commonly used in residential heating system.To mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is developed.The new recharging system can be used in three operational modes.In this paper,a ground-coupled heat recovery ventilation(HRV)model is discussed.A thermal model is set up to find the optimal brine flow rate and heat transfer allocation ratio between exhaust and supply coils for maximum heat recovery efficiency.Contrary to the conventional liquid-loop HRV systems,the brine temperature entering the exhaust coil never goes blow zero(0℃),and hence defrosting is needless in the ground-coupled HRV system.This can make the ground-coupled HRV system over 20% more efficient than a conventional HRV system at low outdoor temperatures.展开更多
The Photovoltaic/thermal(PV/T)system combines the conventional PV panel with solar collector into one integrated system,which could achieve the function of generating power and providing thermal energy at the same tim...The Photovoltaic/thermal(PV/T)system combines the conventional PV panel with solar collector into one integrated system,which could achieve the function of generating power and providing thermal energy at the same time.Recently,it has become the most promising solar system for building applications.Most of the PV/T systems use water as the coolant,which could cause freezing problem in winter.To overcome this problem,the heat pipe PV/T system is developed to provide electrical and thermal energy stably without the seasonal barrier.Although some published review works have involved this type of PV/T system,they just stated a simple introduction on it,acting as a small part of their works.This paper focuses on the heat pipe PV/T system independently and provides a comprehensive and in-depth analysis of its performance.Firstly,the structure and operational principles of the heat pipe PV/T module and system are introduced concisely.Then the features and performance of different types of heat pipe PV/T systems,i.e.,integral heat pipe,loop heat pipe,and pulsating heat pipe PV/T system,are presented and analyzed.This is followed by the review on the performance of the systems which combine heat pipe PV/T module and other devices.Finally,the research gaps in this field are identified,and some future research trends and directions are recommended.展开更多
The undisturbed ground temperatures are important for design of the ground heat exchangers in ground source heat pump （GSHP） systems. In this paper, the undisturbed ground temperatures measured in two different me...The undisturbed ground temperatures are important for design of the ground heat exchangers in ground source heat pump （GSHP） systems. In this paper, the undisturbed ground temperatures measured in two different methods are presented. The investigation was carried out in two cases. The temperature measured with the direct method is assumed to give the correct undisturbed ground temperature profile. The temperature measured with indirect method overestimates the undisturbed ground temperature by 2.1℃ and 1.7~C. This difference is mainly caused by the circulation pump and ambient air to the fluid. Therefore, the results that are decreased about 2℃ as compared with the indirect measured are recommended to estimate the undisturbed ground temperature in situ measuring. A smaller pump or deeper borehole or mild weather would result in a more correct temperature. Because the undisturbed ground temperature is affected by many factors. Whether or not these conclusions are correct to other areas, this would need further investigation.展开更多
基金sponsored by National Key R&D Program of China(Grant No.2020YFE0200300)Applied Basic Research Project of Sichuan Province(Project No.2017JY0253)Fundamental Research Funds for the Central Universities(Project No.2682020CX28 and 2682020CX36)。
文摘Hydrogen is a type of clean energy which has the potential to replace the fossil energy for transportation,domestic and industrial applications.To expand the hydrogen production method and reduce the consumption of fossil energy,technologies of using renewable energy to generate hydrogen have been developed widely.Due to the advantages of widespread distribution and various hydrogen production methods,most of the research or review works focus on the solar and biomass energy hydrogen production systems.To achieve a comprehensive acknowledge on the development state of current renewable energy hydrogen production technology,a review on hydrogen production systems driven by solar,wind,biomass,geothermal,ocean and hydropower energy has been presented.The reaction process,energy efficiency,exergy efficiency,hydrogen production rate,economic and environmental performance of these systems have been evaluated.Based on the analysis of these different systems,the challenge and prospects of them are also analyzed.
基金supported by the Key Research and Development Program of Anhui Province(No.S202004a07020029).
文摘Architects welcome double skin facade(DSF)due to its aesthetic quality.The first DSF structure was intended to prevent cold weather and strong winds.Nowadays,the application of DSF under different climates has been investigated in many previous studies.Fiowever,little work had been done on the behaviour of DSF in hot and humid climates.Therefore,this paper aimed to extend the application into this specific climate and Guangzhou was selected as the sample city.Both the climate and the design influence the performance of DSF.In this paper,rather than explore how each design parameter influences the performance,the design was evaluated from an overall aspect.The Designbuilder software was used to build the single skin facade(SSF)and double skin facade base model.Annual HVAC energy consumption for both the two models was calculated and compared.An optimisation process was conducted to figure out what kinds of parameter combination could make the design more energy-saving and thermally comfortable.The results indicated that it was possible to design an energy-saving DSF system applied in hot and humid climates compared with the SSF model.The efficiency of the DSF could be further enhanced with a better parameter combination.The optimised options had some features in common,which could provide some inspirations for the application of DSF in hot and humid climates.
基金supported by grants from the Key Research and Development Program of Anhui Province(No.S202004a07020029)National Natural Science Foundation of China(No.51908174)Anhui Provincial Natural Science Foundation(No.1908085QE206).
文摘Switchable multi-layer ethylene tetra-fluoro-ethylene(ETFE)cushion controls the natural light and heat flux passing through the cushion with varying outdoor conditions by dynamically modifying its properties.In this paper,the switchable ETFE cushions with ink printing of different optical and thermal properties were adopted as the window in a typical office model,and the indoor daylight and energy consumption were simulated by using Grasshopper software.Experimental model was built to validate the numerical model.Five locations representing five climate zones in China were selected to analyze the feasibility of the switchable ETFE cushion in different climates.The hourly indoor daylight and heat gain in a single day revealed the effects of the dynamic mechanism of ETFE cushion in improving indoor natural light and thermal environment.In addition,the annual daylight performance at the working area(1.5 m from the window)was simulated.ETFE cushion with printing of the lowest transmittance(ETFE1)was the optimal option for most cities and window-to-wall ratios,with the percentage of annual useful daylight hours up to 78.6%,except for the cases where the window-to-wall ratio(WWR)was 0.35 in Harbin,Beijing,and Hefei.The distribution of useful daylight hours revealed that ETFE cushions with low,medium,and high printing transmittance were suitable for offices where people work in the front,medium,and back region of the room,respectively.Energy consumption calculation revealed that ETFE1 showed advantages over other windows in most cities except for cities highly dominated by heating.ETFE1 delivered up to 33%of energy saving over a year in Kunming compared with the conventional double glazing but was not superior in cities with high heating and low cooling demands,such as Harbin.
基金supported by the grants from the Key Research and Development Program of Anhui Province,China(No.S202004a07020038)the National Natural Science Foundation of China(No.51908174)Anhui Provincial Natural Science Foundation,China(No.1908085QE206).
文摘Building integrated concentrating photovoltaic(BICPV)windows have attracted numerous studies in recent years.However,there is a tradeoff between the light transmittance and power generation efficiency in the design of BICPV window.In this paper,a smart luminescent solar concentrator(LSC)is introduced as the BICPV window.The proposed smart LSC system features on the combination of fluorescent dyes with thermochromic materials to enhance photoelectric conversion efficiency as well as form a dynamic response mechanism to ambient solar radiation and environmental temperature.In this study,a BICPV smart window system consists of the waveguide doped with organic dye Lumogen F Red-305(BASF)and the thermochromic hydrogel membrane has been developed.The research on analytic design parameters is executed through optical simulation by ray tracing technology along with outdoor comparative experiments.From simulations for a smart LSC of 100 mm×100 mm×3 mm with a bottom-mounted solar cell of 100 mm×10 mm,the optical effective concentration is found to be with the range of 1.23 to 1.31 when a highest gain of 1.26 in power over the bare solar cell is obtained from experiments.
文摘Ground-coupled heat pumps(GCHP)are commonly used in residential heating system.To mitigate the boreholes temperature dropping with operating time,a new exhaust-air recharging system is developed.The new recharging system can be used in three operational modes.In this paper,a ground-coupled heat recovery ventilation(HRV)model is discussed.A thermal model is set up to find the optimal brine flow rate and heat transfer allocation ratio between exhaust and supply coils for maximum heat recovery efficiency.Contrary to the conventional liquid-loop HRV systems,the brine temperature entering the exhaust coil never goes blow zero(0℃),and hence defrosting is needless in the ground-coupled HRV system.This can make the ground-coupled HRV system over 20% more efficient than a conventional HRV system at low outdoor temperatures.
基金The work of this paper is sponsored by Sichuan Science and Technology Support Program(19ZDYF1865)Sichuan Science and Technology Program(Project No.2020JDRC0036)+1 种基金Chengdu Science and Technology Project(Project No.2019-YF05-01326-SN)Fundamental Research Funds for the Central Universities(Project No.2682020CX36).
文摘The Photovoltaic/thermal(PV/T)system combines the conventional PV panel with solar collector into one integrated system,which could achieve the function of generating power and providing thermal energy at the same time.Recently,it has become the most promising solar system for building applications.Most of the PV/T systems use water as the coolant,which could cause freezing problem in winter.To overcome this problem,the heat pipe PV/T system is developed to provide electrical and thermal energy stably without the seasonal barrier.Although some published review works have involved this type of PV/T system,they just stated a simple introduction on it,acting as a small part of their works.This paper focuses on the heat pipe PV/T system independently and provides a comprehensive and in-depth analysis of its performance.Firstly,the structure and operational principles of the heat pipe PV/T module and system are introduced concisely.Then the features and performance of different types of heat pipe PV/T systems,i.e.,integral heat pipe,loop heat pipe,and pulsating heat pipe PV/T system,are presented and analyzed.This is followed by the review on the performance of the systems which combine heat pipe PV/T module and other devices.Finally,the research gaps in this field are identified,and some future research trends and directions are recommended.
文摘The undisturbed ground temperatures are important for design of the ground heat exchangers in ground source heat pump （GSHP） systems. In this paper, the undisturbed ground temperatures measured in two different methods are presented. The investigation was carried out in two cases. The temperature measured with the direct method is assumed to give the correct undisturbed ground temperature profile. The temperature measured with indirect method overestimates the undisturbed ground temperature by 2.1℃ and 1.7~C. This difference is mainly caused by the circulation pump and ambient air to the fluid. Therefore, the results that are decreased about 2℃ as compared with the indirect measured are recommended to estimate the undisturbed ground temperature in situ measuring. A smaller pump or deeper borehole or mild weather would result in a more correct temperature. Because the undisturbed ground temperature is affected by many factors. Whether or not these conclusions are correct to other areas, this would need further investigation.
