With the growth of intermittent renewable energy generation in power grids,there is an increasing demand for controllable resources to be deployed to guarantee power quality and frequency stability.The flexibility of ...With the growth of intermittent renewable energy generation in power grids,there is an increasing demand for controllable resources to be deployed to guarantee power quality and frequency stability.The flexibility of demand response(DR)resources has become a valuable solution to this problem.However,existing research indicates that problems on flexibility prediction of DR resources have not been investigated.This study applied the temporal convolution network(TCN)-combined transformer,a deep learning technique to predict the aggregated flexibility of two types of DR resources,that is,electric vehicles(EVs)and domestic hot water system(DHWS).The prediction uses historical power consumption data of these DR resources and DR signals(DSs)to facilitate prediction.The prediction can generate the size and maintenance time of the aggregated flexibility.The accuracy of the flexibility prediction results was verified through simulations of case studies.The simulation results show that under different maintenance times,the size of the flexibility changed.The proposed DR resource flexibility prediction method demonstrates its application in unlocking the demand-side flexibility to provide a reserve to grids.展开更多
Monochloramine is a well-known disinfectant for drinking water with several advantages over chlorine and chlorine dioxide. With these two biocides, monochloramine is included in the US-EPA list of disinfectants for dr...Monochloramine is a well-known disinfectant for drinking water with several advantages over chlorine and chlorine dioxide. With these two biocides, monochloramine is included in the US-EPA list of disinfectants for drinking water. At the beginning of XXI century, epidemiological studies demonstrated its superior ability to control Legionella in hot water health-care premises. In 2005 a research program started to set up a reliable and effective method to produce monochloramine directly in domestic hot water systems, at the safest concentration and without accumulation of by-products. Results of these researches, which has been carried out with the collaboration of Italian and American Institutions showed that monochloramine can be safely and reliably prepared and that it is the best approach to Legionella remediation in health-care facilities.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
The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the coll...The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the collection of wastewater samples. Their analysis revealed specific pollutant loads, including loads of BOD5 3.6966 kgO<sub>2</sub>/day and COD of 12.8775 kgO<sub>2</sub>/day, which were central to the design phase. Following a rigorous assessment of the existing sanitation infrastructure, constructed wetland (CWs) emerged as the most appropriate ecological solution. This system, valued for its ability to effectively remove contaminants, was tailored to the specific needs of the site. Consequently, the final design of the filter extends over 217.16 m<sup>2</sup>, divided into two cells of 108.58 m<sup>2</sup> each, with dimensions of 12.77 m in length and 8.5 m in width. The depth of the filtering medium is approximately 0.60 m, meeting the standards while ensuring maximized purification. Typha, an indigenous and prolific plant known for its purification abilities, was selected as the filtering agent. Concurrently, non-crushed gravel was chosen for its proven filtration capacity. This study is the result of a combination of scientific rigor and design expertise. It provides a holistic view of sanitation for Ndiebene Gandiol. The technical specifications and dimensions of the constructed wetland filter embody an approach that marries indepth analysis and practical application, all aimed at delivering an effective and long-lasting solution to the local sanitation challenges. By integrating precise scientific data with sanitation design expertise, this study delivers a holistic solution for Ndiebene Gandiol. The detailed dimensions and specifications of the constructed wetland filter reflect a methodology that combines meticulous analysis with practical adaptation, aiming to provide an effective and sustainable response to the challenges of rural and school sanitation in the northern region of Senegal.展开更多
Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and...Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management practices.In this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of China.Photosynthetic capacity and needle stable carbon isotope composition(δ^(13)C)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were insignificant.However,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water content.Understory removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability.In general,thinning may be an appropriate management measure to promote P.massoniana WUE to cope with seasonal droughts under future extreme climates.展开更多
Desalination is emerging as a promising alternative among various technologies to resolve water shortage. However, desalination requires a sufficient energy and cooling device and therefore poses limitations for its i...Desalination is emerging as a promising alternative among various technologies to resolve water shortage. However, desalination requires a sufficient energy and cooling device and therefore poses limitations for its installation and application. In particular, many countries suffering water deficits are economically underdeveloped and cannot afford the technology. As this technology, which changes seawater into freshwater, has little environmental impact, developed countries will need to assist less developed countries to introduce this technology as a humanitarian effort. This will help reduce the number of countries that have experienced difficulty with development.展开更多
The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limi...The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern space.The entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each other.Particularly,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion system.This study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle contour.Most existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow field.However,research has yet to implement an integrated,optimal design of the section from the rotor to the nozzle.Given the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the findings.This program used an existing model as the design case.This study referred to the actual trial data as the design conditions for the proposed model.Unlike prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational domain.After the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual condition.Based on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be linear.Furthermore,for the pump head,static pressure had a more significant impact than dynamic pressure.展开更多
Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optim...Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering fouling.However,low flow velocity promotes fouling.Therefore,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation.This study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this goal.The model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and fouling.By optimizing the concentration cycle of the CCWS,water conservation and fouling control can be achieved.The model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance coefficient.Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation decrease.In periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate.Overall,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.展开更多
Hematite(α-Fe_(2)O_(3)) based photoanodes have been extensively studied due to various intriguing features that make them viable candidates for a photoelectrochemical(PEC) water splitting photoanode.Herein,we propose...Hematite(α-Fe_(2)O_(3)) based photoanodes have been extensively studied due to various intriguing features that make them viable candidates for a photoelectrochemical(PEC) water splitting photoanode.Herein,we propose a Zr-doped Fe_(2)O_(3) photoanode decorated with facilely spin-coated Au nanoparticles(NPs) and microwave-assisted attached Si co-doping in conjunction with a SiO_(x) overlayer that displayed a remarkable photocurrent density of 2.01 mA/cm^(2) at 1.23 V vs.RHE.The kinetic dynamics at the photoelectrode/-electrolyte interface was examined by employing systematic electrochemical investigations.The Au NPs played a dual role in increasing PEC water splitting.First,the Schottky interface that was formed between Au NPs and Zr-Fe_(2)O_(3) lectrode ensured the prevention of electron flow from the photoanode to the metal,increasing the number of available charges as well as suppressing surface charge recombination.Second,Au extracted photoholes from the bulk of the Zr-Fe_(2)O_(3) and transported them to the outer SiO_(x) overlayer,while the SiO_(x) overlayer efficiently collected the photoholes and promoted the hole injection into the electrolyte.Further,Si co-doping enhanced bulk conductivity by reducing bulk charge transfer resistance and improving charge carrier density.This study outlines a technique to design a metallic charge transfer path with an overlayer for solar energy conversion.展开更多
Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor...Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWR)is a fourth-generation conceptual reactor.In an SCWR,the non-linear dynamics of the reactor require a controller capable of control-ling the nonlinearities.In this study,a pressure-tube-type SCWR was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled simultaneously.In an SCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power maneuvering.Reactor point kinetics equations with three groups of delayed neutrons were used in the simulation.Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous studies.The controlled parameters were reactor power,steam temperature,and pressure.Notably,for these parameters,the PI controller had certain instabilities in the presence of disturbances.The classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering phenomenon.HOSMC was highly accurate and stable and had a small computational cost.In reality,it followed the desired values without oscillations and chattering.展开更多
For the use of green hydrogen energy,it is crucial to have efficient photocatalytic activity for hydrogen generation by water reforming of methanol under mild conditions.Much attention has been paid to gC_(3)N_(4)as a...For the use of green hydrogen energy,it is crucial to have efficient photocatalytic activity for hydrogen generation by water reforming of methanol under mild conditions.Much attention has been paid to gC_(3)N_(4)as a promising photocatalyst for the generation of hydrogen.To improve the separation of photogenerated charge,porous nanosheet g-C_(3)N_(4)was modified with Pt nanoclusters(Pt/g-C_(3)N_(4))through impregnation and following photo-induced reduction.This catalyst showed excellent photocatalytic activity of water reforming of methanol fo r hydrogen production with a 17.12 mmol·g^(-1)·h^(-1)rate at room temperature,which was 311 times higher than that of the unmodified g-C_(3)N_(4).The strong interactions of Pt-N in Pt/g-C_(3)N_(4)constructed effective electron transfer channels to promote the separation of photogenerated electrons and holes effectively.In addition,in-situ infrared spectroscopy was used to investigate the intermediates of the hydrogen production reaction,which proved that methanol and water eventually turn into H_(2)and CO_(2)via formaldehyde and formate.This study provides insights for understanding the photocatalytic hydrogen production in the water reforming of methanol.展开更多
Superwetting materials have drawn unprecedented attention in the treatment of oily wastewater due to their preferable anti-fouling property and selective oil/water separation.However,it is still a challenge to fabrica...Superwetting materials have drawn unprecedented attention in the treatment of oily wastewater due to their preferable anti-fouling property and selective oil/water separation.However,it is still a challenge to fabricate multifunctional and environmentally friendly materials,which can be stably applied to purify the actual complicated wastewater.Here,a Ag/Ag/α-Fe_(2)O_(3) heterostructure anchored copper mesh was intentionally synthesized using a facile two-step hydrothermal method.The resultant mesh with superhydrophilicity and underwater superoleophobicity was capable of separating various oil/water mixtures with superior separation efficiency and high permeationflux driven by gravity.Benefiting from the joint effects of the smaller band gap of Ag/α-Fe_(2)O_(3) heterojunction,inherent antibacterial capacity of Ag/α-Fe_(2)O_(3) and Ag nanoparticles,favorable conductive substrate,as well as the hierarchical structure with superwettability,such mesh presented remarkably enhanced degradation capability toward organic dyes under visible light irradiation and antibacterial activity against both Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)compared with the pure Ag/α-Fe_(2)O_(3) coated mesh.Impressively,the mesh exhibited bifunctional water purification performance,in which organic dyes were eliminated simultaneously from water during oil/water separation in onefiltration process.More importantly,this mesh behaved exceptional chemical resistance,mechanical stability and long-term reusability.Therefore,this material with multifunctional integration may hold promising potential for steady water purification in practice.展开更多
The integration of the photocatalytic effect into solar steam is highly desirable for addressing freshwater shortages and water pollution.Here,a ternary film structure for the adsorption and photothermal and photocata...The integration of the photocatalytic effect into solar steam is highly desirable for addressing freshwater shortages and water pollution.Here,a ternary film structure for the adsorption and photothermal and photocatalytic treatment of wastewater was designed by combining the technique of self-assembled carbon nano paper with a nitrogen composite titanium dioxide(N-TiO_(2))deposited on the surface of carbon nanotubes(CNT)using polyvinylidene fluoride(PVDF)as a substrate.The photogeneration of reactive oxygen species can be promoted by rapid oxygen diffusion at the three-phase interface,whereas the interfacial photothermal effect promotes subsequent free radical reactions for the degradation of rhodamine B(93%).The freshwater evaporation rate is 1.35 kg·m^(-2)·h^(-1)and the solar-to-water evaporation efficiency is 94%.Importantly,the N-TiO_(2)/CNT/PVDF(N-TCP)film not only effectively resists mechanical damage from the environment and maintains structural integrity,but can also be made into a large film for outdoor experiments in a large solar energy conversion device to collect fresh water from polluted water and degrade organic dyes in source water simultaneously,opening the way for applications in energy conversion and storage.展开更多
This study uses the Life Cycle Analysis (LCA) to evaluate the magnitude of the environmental impact, in terms of global warming potential, and water footprint throughout the 20 years of useful life of a rural electric...This study uses the Life Cycle Analysis (LCA) to evaluate the magnitude of the environmental impact, in terms of global warming potential, and water footprint throughout the 20 years of useful life of a rural electrical energy concession comprised of 120Wp Households photovoltaic systems (HPS) in the isolated communities of San Martin, in the Peruvian Amazon region. On the other hand, due to the particular conditions of the system (installation, operation, maintenance, monthly tariff collection), it is necessary to know its real impact and sustainability;not only through the aforementioned environmental impact indicators, but also by energy intensity values required by the system throughout its life cycle. Therefore, this paper used the Cumulative energy demand (CED) method to determine the amount of energy taken from natural resources for each process involved in the LCA and calculated with this, i.e., the Energy Payback Time (EPBT) of the whole system. Likewise, the HPS has been environmentally compared to other case studies and the Peruvian Energy Mix, revealing a lower impact in the latter case and results within the range for stand-alone systems. Besides, the HPS shows a strong relation between energy production and O&M condition. Additionally, this study allows a further promotion of the use of this type of system in isolated areas, as well as the diversification of electricity generation in Peru.展开更多
For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention....For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.展开更多
The shortage of fresh water in the world has brought upon a serious crisis to human health and economic development.Solar‐driven interfacial photothermal conversion water evaporation including evaporating seawater,la...The shortage of fresh water in the world has brought upon a serious crisis to human health and economic development.Solar‐driven interfacial photothermal conversion water evaporation including evaporating seawater,lake water,or river water has been recognized as an environmentally friendly process for obtaining clean water in a low‐cost way.However,water transport is restricted by itself by solar energy absorption capacity's limits,especially for finite evaporation rates and insufficient working life.Therefore,it is important to seek photothermal conversion materials that can efficiently absorb solar energy and reasonably design solar‐driven interfacial photothermal conversion water evaporation devices.This paper reviews the research progress of carbon‐based photothermal conversion materials and the mechanism for solar‐driven interfacial photothermal conversion water evaporation,as well as the summary of the design and development of the devices.Based on the research progress and achievements of photothermal conversion materials and devices in the fields of seawater desalination and photothermal electric energy generation in recent years,the challenges and opportunities faced by carbon‐based photothermal conversion materials and devices are discussed.The prospect of the practical application of solar‐driven interfacial photothermal conversion evaporation technology is foreseen,and theoretical guidance is provided for the further development of this technology.展开更多
Performance improvement of existing 200 litres capacity natural convection type domestic solar hot water system is attempted.A two-stage centrifugal pump driven by a vertical axis windmill having Savonius type rotor i...Performance improvement of existing 200 litres capacity natural convection type domestic solar hot water system is attempted.A two-stage centrifugal pump driven by a vertical axis windmill having Savonius type rotor is added to the fluid loop.The windmill driven pump circulates the water through the collector.The system with necessary instrumentation is tested over a day.Tests on Natural Circulation System(NCS)mode and Wind Assisted System(WAS)mode are carried out during January,April,July and October,2009.Test results of a clear day are reported.Daily average efficiency of 25-28% during NCS mode and 33-37% during WAS mode are obtained.With higher wind velocities,higher collector flow rates and hence higher efficiencies are obtained.In general,WAS mode provides improvements in efficiency when compared to NCS mode.展开更多
Carbon neutrality is widely concerned and highly valued by many countries.Biosphere has always maintained the balance between oxidized organic substances and assimilated organic matter,resulting in netzero carbon diox...Carbon neutrality is widely concerned and highly valued by many countries.Biosphere has always maintained the balance between oxidized organic substances and assimilated organic matter,resulting in netzero carbon dioxide(CO_(2)) emissions and maintaining its own carbon neutrality.Nature has set a good example for human beings to coordinate oxygen(O_(2)) balance and CO_(2)balance,and achieve carbon neutrality.How does photosynthetic oxygen evolution initiate carbon and water neutrality?My synthesis shows that photo system Ⅱ functions as carbonic anhydrase to catalyze the reaction of CO_(2)hydration under physiological conditions,and CO_(2)hydration coupled with chemical equilibrium,H^(+)+HCO_(3)^(-)→1/2O_(2)+2e^(-)+2H^(+)+CO_(2),occurs in a photosystem Ⅱ corecomplex.Meanwhile,I focused on the revisiting of four classical heavy oxygen(O^(18)) labeling experiments and found that bicarbonate can promote photo synthetic oxygen evolution,and that photo synthetic oxygen evolution can alternately come from bicarbonate and water,not only water.Bicarbonate photolysis and water photolysis account for half of the photo synthetic oxygen evolution respectively,which can well explain the bicarbonate effect,Dole effect and plants’ environmental adaptability.Photosynthetic oxygen evolution initiated the journey of water metabolism and carbon metabolism in nature,which led to the coupling as 1:1(mol/mol) stoichiometric relationship between the reduction of CO_(2)and oxidation of organic carbon,coordinated the evolution of the atmosphere,hydrosphere,lithosphere and biosphere,and realized "carbon neutrality" in the whole Earth system.展开更多
基金This work was supported by the National Natural Science Foundation of China(51877078 and 52061635102)the Beijing Nova Program(Z201100006820106).
文摘With the growth of intermittent renewable energy generation in power grids,there is an increasing demand for controllable resources to be deployed to guarantee power quality and frequency stability.The flexibility of demand response(DR)resources has become a valuable solution to this problem.However,existing research indicates that problems on flexibility prediction of DR resources have not been investigated.This study applied the temporal convolution network(TCN)-combined transformer,a deep learning technique to predict the aggregated flexibility of two types of DR resources,that is,electric vehicles(EVs)and domestic hot water system(DHWS).The prediction uses historical power consumption data of these DR resources and DR signals(DSs)to facilitate prediction.The prediction can generate the size and maintenance time of the aggregated flexibility.The accuracy of the flexibility prediction results was verified through simulations of case studies.The simulation results show that under different maintenance times,the size of the flexibility changed.The proposed DR resource flexibility prediction method demonstrates its application in unlocking the demand-side flexibility to provide a reserve to grids.
文摘Monochloramine is a well-known disinfectant for drinking water with several advantages over chlorine and chlorine dioxide. With these two biocides, monochloramine is included in the US-EPA list of disinfectants for drinking water. At the beginning of XXI century, epidemiological studies demonstrated its superior ability to control Legionella in hot water health-care premises. In 2005 a research program started to set up a reliable and effective method to produce monochloramine directly in domestic hot water systems, at the safest concentration and without accumulation of by-products. Results of these researches, which has been carried out with the collaboration of Italian and American Institutions showed that monochloramine can be safely and reliably prepared and that it is the best approach to Legionella remediation in health-care facilities.
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The primary objective of this study was to design and size a sustainable sanitation solution for the Ndiebene Gandiol 1 school located in the eponymous commune in northern Senegal. Field investigations led to the collection of wastewater samples. Their analysis revealed specific pollutant loads, including loads of BOD5 3.6966 kgO<sub>2</sub>/day and COD of 12.8775 kgO<sub>2</sub>/day, which were central to the design phase. Following a rigorous assessment of the existing sanitation infrastructure, constructed wetland (CWs) emerged as the most appropriate ecological solution. This system, valued for its ability to effectively remove contaminants, was tailored to the specific needs of the site. Consequently, the final design of the filter extends over 217.16 m<sup>2</sup>, divided into two cells of 108.58 m<sup>2</sup> each, with dimensions of 12.77 m in length and 8.5 m in width. The depth of the filtering medium is approximately 0.60 m, meeting the standards while ensuring maximized purification. Typha, an indigenous and prolific plant known for its purification abilities, was selected as the filtering agent. Concurrently, non-crushed gravel was chosen for its proven filtration capacity. This study is the result of a combination of scientific rigor and design expertise. It provides a holistic view of sanitation for Ndiebene Gandiol. The technical specifications and dimensions of the constructed wetland filter embody an approach that marries indepth analysis and practical application, all aimed at delivering an effective and long-lasting solution to the local sanitation challenges. By integrating precise scientific data with sanitation design expertise, this study delivers a holistic solution for Ndiebene Gandiol. The detailed dimensions and specifications of the constructed wetland filter reflect a methodology that combines meticulous analysis with practical adaptation, aiming to provide an effective and sustainable response to the challenges of rural and school sanitation in the northern region of Senegal.
基金supported by the National Key Research and Development Program of China(2016YFD0600201)the National Nonprofit Institute Research Grant of CAF(CAFYBB2017ZB003)+1 种基金the National Natural Science Foundation of China(3187071631670720)。
文摘Understanding the relationship between forest management and water use efficiency(WUE)is important for evaluating forest adaptability to climate change.However,the effects of thinning and understory removal on WUE and its key controlling processes are not well understood,which limits our comprehension of the physiological mechanisms of various management practices.In this study,four forest management measures(no thinning:NT;understory removal:UR;light thinning:LT;and heavy thinning:HT)were carried out in Pinus massoniana plantations in a subtropical region of China.Photosynthetic capacity and needle stable carbon isotope composition(δ^(13)C)were measured to assess instantaneous water use efficiency(WUE_(inst))and long-term water use efficiency(WUE_(i)).Multiple regression models and structural equation modelling(SEM)identified the effects of soil properties and physiological performances on WUE_(inst)and WUE_(i).The results show that WUE_(inst)values among the four treatments were insignificant.However,compared with the NT stand(35.8μmol·mol^(-1)),WUE_(i)values significantly increased to 41.7μmol·mol^(-1)in the UR,50.1μmol·mol^(-1)in the LT and 46.6μmol·mol^(-1)in HT treatments,largely explained by photosynthetic capacity and soil water content.Understory removal did not change physiological performance(needle water potential and photosynthetic capacity).Thinning increased the net photosynthetic rate(A_n)but not stomatal conductance(g_s)or predawn needle water potential(ψ_(pd)),implying that the improvement in water use efficiency for thinned stands was largely driven by radiation interception than by soil water availability.In general,thinning may be an appropriate management measure to promote P.massoniana WUE to cope with seasonal droughts under future extreme climates.
文摘Desalination is emerging as a promising alternative among various technologies to resolve water shortage. However, desalination requires a sufficient energy and cooling device and therefore poses limitations for its installation and application. In particular, many countries suffering water deficits are economically underdeveloped and cannot afford the technology. As this technology, which changes seawater into freshwater, has little environmental impact, developed countries will need to assist less developed countries to introduce this technology as a humanitarian effort. This will help reduce the number of countries that have experienced difficulty with development.
基金the financial support from the National Science and Technology Council,Taiwan(Grant No.MOST 111-2221-E-019-035-).
文摘The performance of a water jet propulsion system is related to the inlet duct,rotor,stator,and nozzle.Generally,the flow inlet design must fit the bottom line of the hull,and the design of the inlet duct is often limited by stern space.The entire section,from the rotor to the nozzle through the stator,must be designed based on system integration in that the individual performance of these three components will influence each other.Particularly,the section from the rotor to the nozzle significantly impacts the performance of a water jet propulsion system.This study focused on nozzle design and established referable analysis results to facilitate subsequent integrated studies on the design parameters regarding nozzle contour.Most existing studies concentrate on discussions on rotor design and the tip leakage flow of rotors or have replaced the existing complex computational domain with a simple flow field.However,research has yet to implement an integrated,optimal design of the section from the rotor to the nozzle.Given the above,our program conducted preliminary research on this system integration design issue,discussed the optimal nozzle for this section in-depth,and proposed design suggestions based on the findings.This program used an existing model as the design case.This study referred to the actual trial data as the design conditions for the proposed model.Unlike prior references’simple flow field form,this study added a jet ski geometry and free surface to the computational domain.After the linear hull shape was considered,the inflow in the inlet duct would be closer to the actual condition.Based on the numerical calculation result,this study recommends that the optimal nozzle outlet area should be 37%of the inlet area and that the nozzle contour should be linear.Furthermore,for the pump head,static pressure had a more significant impact than dynamic pressure.
基金Financial support from the National Natural Science Foundation of China (22022816 and 22078358)
文摘Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering fouling.However,low flow velocity promotes fouling.Therefore,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation.This study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this goal.The model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and fouling.By optimizing the concentration cycle of the CCWS,water conservation and fouling control can be achieved.The model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance coefficient.Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation decrease.In periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate.Overall,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(NRF-2021R1A2C1095669,NRF-2021R1F1A1049366 and NRF2023R1A2C1003088)supported by the GRDC(Global Research Development Center)Cooperative Hub Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(MSIT)(RS-202300258911)。
文摘Hematite(α-Fe_(2)O_(3)) based photoanodes have been extensively studied due to various intriguing features that make them viable candidates for a photoelectrochemical(PEC) water splitting photoanode.Herein,we propose a Zr-doped Fe_(2)O_(3) photoanode decorated with facilely spin-coated Au nanoparticles(NPs) and microwave-assisted attached Si co-doping in conjunction with a SiO_(x) overlayer that displayed a remarkable photocurrent density of 2.01 mA/cm^(2) at 1.23 V vs.RHE.The kinetic dynamics at the photoelectrode/-electrolyte interface was examined by employing systematic electrochemical investigations.The Au NPs played a dual role in increasing PEC water splitting.First,the Schottky interface that was formed between Au NPs and Zr-Fe_(2)O_(3) lectrode ensured the prevention of electron flow from the photoanode to the metal,increasing the number of available charges as well as suppressing surface charge recombination.Second,Au extracted photoholes from the bulk of the Zr-Fe_(2)O_(3) and transported them to the outer SiO_(x) overlayer,while the SiO_(x) overlayer efficiently collected the photoholes and promoted the hole injection into the electrolyte.Further,Si co-doping enhanced bulk conductivity by reducing bulk charge transfer resistance and improving charge carrier density.This study outlines a technique to design a metallic charge transfer path with an overlayer for solar energy conversion.
文摘Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWR)is a fourth-generation conceptual reactor.In an SCWR,the non-linear dynamics of the reactor require a controller capable of control-ling the nonlinearities.In this study,a pressure-tube-type SCWR was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled simultaneously.In an SCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power maneuvering.Reactor point kinetics equations with three groups of delayed neutrons were used in the simulation.Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous studies.The controlled parameters were reactor power,steam temperature,and pressure.Notably,for these parameters,the PI controller had certain instabilities in the presence of disturbances.The classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering phenomenon.HOSMC was highly accurate and stable and had a small computational cost.In reality,it followed the desired values without oscillations and chattering.
基金supported by the National Natural Science Foundation of China(51672081)the Program of Tri-three Talents Project of Hebei Province(China,A202110002)+1 种基金the Young Top Talents Fund Program of Higher Education Institutions of Heibei Province(BJ2020009)the Project of Science and Technology Innovation Team,Tangshan(20130203D)。
文摘For the use of green hydrogen energy,it is crucial to have efficient photocatalytic activity for hydrogen generation by water reforming of methanol under mild conditions.Much attention has been paid to gC_(3)N_(4)as a promising photocatalyst for the generation of hydrogen.To improve the separation of photogenerated charge,porous nanosheet g-C_(3)N_(4)was modified with Pt nanoclusters(Pt/g-C_(3)N_(4))through impregnation and following photo-induced reduction.This catalyst showed excellent photocatalytic activity of water reforming of methanol fo r hydrogen production with a 17.12 mmol·g^(-1)·h^(-1)rate at room temperature,which was 311 times higher than that of the unmodified g-C_(3)N_(4).The strong interactions of Pt-N in Pt/g-C_(3)N_(4)constructed effective electron transfer channels to promote the separation of photogenerated electrons and holes effectively.In addition,in-situ infrared spectroscopy was used to investigate the intermediates of the hydrogen production reaction,which proved that methanol and water eventually turn into H_(2)and CO_(2)via formaldehyde and formate.This study provides insights for understanding the photocatalytic hydrogen production in the water reforming of methanol.
基金This work was financially supported by the Shandong Provincial Natural Science Foundation(ZR2020QB116)the Excellent Young Talents Foundation in Universities of Anhui Province(gxyq2021223)the Key Research Project of Natural Science in Universities of Anhui Province.(KJ2020A0749).
文摘Superwetting materials have drawn unprecedented attention in the treatment of oily wastewater due to their preferable anti-fouling property and selective oil/water separation.However,it is still a challenge to fabricate multifunctional and environmentally friendly materials,which can be stably applied to purify the actual complicated wastewater.Here,a Ag/Ag/α-Fe_(2)O_(3) heterostructure anchored copper mesh was intentionally synthesized using a facile two-step hydrothermal method.The resultant mesh with superhydrophilicity and underwater superoleophobicity was capable of separating various oil/water mixtures with superior separation efficiency and high permeationflux driven by gravity.Benefiting from the joint effects of the smaller band gap of Ag/α-Fe_(2)O_(3) heterojunction,inherent antibacterial capacity of Ag/α-Fe_(2)O_(3) and Ag nanoparticles,favorable conductive substrate,as well as the hierarchical structure with superwettability,such mesh presented remarkably enhanced degradation capability toward organic dyes under visible light irradiation and antibacterial activity against both Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)compared with the pure Ag/α-Fe_(2)O_(3) coated mesh.Impressively,the mesh exhibited bifunctional water purification performance,in which organic dyes were eliminated simultaneously from water during oil/water separation in onefiltration process.More importantly,this mesh behaved exceptional chemical resistance,mechanical stability and long-term reusability.Therefore,this material with multifunctional integration may hold promising potential for steady water purification in practice.
基金Scientific Research Fund of Zhejiang Provincial Education Department(Y202250501)SRT Research Project of Jiaxing Nanhu University。
文摘The integration of the photocatalytic effect into solar steam is highly desirable for addressing freshwater shortages and water pollution.Here,a ternary film structure for the adsorption and photothermal and photocatalytic treatment of wastewater was designed by combining the technique of self-assembled carbon nano paper with a nitrogen composite titanium dioxide(N-TiO_(2))deposited on the surface of carbon nanotubes(CNT)using polyvinylidene fluoride(PVDF)as a substrate.The photogeneration of reactive oxygen species can be promoted by rapid oxygen diffusion at the three-phase interface,whereas the interfacial photothermal effect promotes subsequent free radical reactions for the degradation of rhodamine B(93%).The freshwater evaporation rate is 1.35 kg·m^(-2)·h^(-1)and the solar-to-water evaporation efficiency is 94%.Importantly,the N-TiO_(2)/CNT/PVDF(N-TCP)film not only effectively resists mechanical damage from the environment and maintains structural integrity,but can also be made into a large film for outdoor experiments in a large solar energy conversion device to collect fresh water from polluted water and degrade organic dyes in source water simultaneously,opening the way for applications in energy conversion and storage.
文摘This study uses the Life Cycle Analysis (LCA) to evaluate the magnitude of the environmental impact, in terms of global warming potential, and water footprint throughout the 20 years of useful life of a rural electrical energy concession comprised of 120Wp Households photovoltaic systems (HPS) in the isolated communities of San Martin, in the Peruvian Amazon region. On the other hand, due to the particular conditions of the system (installation, operation, maintenance, monthly tariff collection), it is necessary to know its real impact and sustainability;not only through the aforementioned environmental impact indicators, but also by energy intensity values required by the system throughout its life cycle. Therefore, this paper used the Cumulative energy demand (CED) method to determine the amount of energy taken from natural resources for each process involved in the LCA and calculated with this, i.e., the Energy Payback Time (EPBT) of the whole system. Likewise, the HPS has been environmentally compared to other case studies and the Peruvian Energy Mix, revealing a lower impact in the latter case and results within the range for stand-alone systems. Besides, the HPS shows a strong relation between energy production and O&M condition. Additionally, this study allows a further promotion of the use of this type of system in isolated areas, as well as the diversification of electricity generation in Peru.
基金supported by the National Natural Science Foundation of China(Grants No.52179062 and 51879087).
文摘For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.
基金Natural Science Foundation of Shandong Province,Grant/Award Number:ZR2019MB019National Natural Science Foundation of China,Grant/Award Numbers:22075122,52071295Research Foundation for Talented Scholars of Linyi University,Grant/Award Number:Z6122010。
文摘The shortage of fresh water in the world has brought upon a serious crisis to human health and economic development.Solar‐driven interfacial photothermal conversion water evaporation including evaporating seawater,lake water,or river water has been recognized as an environmentally friendly process for obtaining clean water in a low‐cost way.However,water transport is restricted by itself by solar energy absorption capacity's limits,especially for finite evaporation rates and insufficient working life.Therefore,it is important to seek photothermal conversion materials that can efficiently absorb solar energy and reasonably design solar‐driven interfacial photothermal conversion water evaporation devices.This paper reviews the research progress of carbon‐based photothermal conversion materials and the mechanism for solar‐driven interfacial photothermal conversion water evaporation,as well as the summary of the design and development of the devices.Based on the research progress and achievements of photothermal conversion materials and devices in the fields of seawater desalination and photothermal electric energy generation in recent years,the challenges and opportunities faced by carbon‐based photothermal conversion materials and devices are discussed.The prospect of the practical application of solar‐driven interfacial photothermal conversion evaporation technology is foreseen,and theoretical guidance is provided for the further development of this technology.
文摘Performance improvement of existing 200 litres capacity natural convection type domestic solar hot water system is attempted.A two-stage centrifugal pump driven by a vertical axis windmill having Savonius type rotor is added to the fluid loop.The windmill driven pump circulates the water through the collector.The system with necessary instrumentation is tested over a day.Tests on Natural Circulation System(NCS)mode and Wind Assisted System(WAS)mode are carried out during January,April,July and October,2009.Test results of a clear day are reported.Daily average efficiency of 25-28% during NCS mode and 33-37% during WAS mode are obtained.With higher wind velocities,higher collector flow rates and hence higher efficiencies are obtained.In general,WAS mode provides improvements in efficiency when compared to NCS mode.
基金foundations of the National Natural Science Foundation of China [No. U1612441-2]Support Plan Projects of Science and Technology Department of Guizhou Province [No.(2021)YB453]。
文摘Carbon neutrality is widely concerned and highly valued by many countries.Biosphere has always maintained the balance between oxidized organic substances and assimilated organic matter,resulting in netzero carbon dioxide(CO_(2)) emissions and maintaining its own carbon neutrality.Nature has set a good example for human beings to coordinate oxygen(O_(2)) balance and CO_(2)balance,and achieve carbon neutrality.How does photosynthetic oxygen evolution initiate carbon and water neutrality?My synthesis shows that photo system Ⅱ functions as carbonic anhydrase to catalyze the reaction of CO_(2)hydration under physiological conditions,and CO_(2)hydration coupled with chemical equilibrium,H^(+)+HCO_(3)^(-)→1/2O_(2)+2e^(-)+2H^(+)+CO_(2),occurs in a photosystem Ⅱ corecomplex.Meanwhile,I focused on the revisiting of four classical heavy oxygen(O^(18)) labeling experiments and found that bicarbonate can promote photo synthetic oxygen evolution,and that photo synthetic oxygen evolution can alternately come from bicarbonate and water,not only water.Bicarbonate photolysis and water photolysis account for half of the photo synthetic oxygen evolution respectively,which can well explain the bicarbonate effect,Dole effect and plants’ environmental adaptability.Photosynthetic oxygen evolution initiated the journey of water metabolism and carbon metabolism in nature,which led to the coupling as 1:1(mol/mol) stoichiometric relationship between the reduction of CO_(2)and oxidation of organic carbon,coordinated the evolution of the atmosphere,hydrosphere,lithosphere and biosphere,and realized "carbon neutrality" in the whole Earth system.
