Optimising energy efficiency of LDPC coded chase combining HARQ system

The Key to Resolving the Energy Crisis: The Development of Renewable EnergyIn the face of the looming energy crisis, the world stands at a crossroads. The traditional energy sources, such as coal, oil, and natural gas, are finite and their extraction and use carry significant environmental costs. As the global population and economic activities continue to grow, the demand for energy is expected to increase exponentially, making the need for sustainable and renewable energy sources more urgent.Renewable energy, derived from sources such as solar, wind, hydroelectric, geothermal, and biomass, offers a promising solution to this crisis. Unlike fossil fuels, these energy sources are infinite and their use does not contribute to greenhouse gas emissions, air pollution, or other environmental problems. Solar power harnesses the vast energy of the sun, wind power taps the constant flow of air, and hydroelectric power converts the kinetic energy of falling water into electricity. Geothermal energy taps the heat stored deep within the earth's crust, while biomass energy utilizes organic matter to generate power.The development of renewable energy not only addresses the immediate problem of energy scarcity but alsocontributes to long-term sustainability. By investing in renewable energy technologies, we can ensure a secureenergy supply for future generations while mitigating the impact of climate change. Furthermore, the transition to renewable energy creates new economic opportunities, spurs innovation, and generates jobs in the clean energy sector.However, the transition to renewable energy is not without challenges. The initial investment costs can be high, and the infrastructure required to support renewable energy systems is extensive. Additionally, theintermittency of some renewable energy sources, such assolar and wind, can pose challenges in ensuring a reliable energy supply.To overcome these challenges, a comprehensive approachis needed. Governments must provide incentives andsubsidies to encourage private sector investment in renewable energy projects. Additionally, they should establish regulations and policies that promote the development and deployment of renewable energy technologies.Research and development efforts should be intensified to improve the efficiency and reliability of renewable energy systems. Furthermore, public education and awareness-raising campaigns are crucial to build support and momentum for the transition to renewable energy.In conclusion, the development of renewable energy is crucial to resolving the energy crisis and achieving sustainable development. By harnessing the vast resourcesof renewable energy, we can ensure a secure and cleanenergy supply for future generations, mitigate the impactof climate change, and create new economic opportunities. The transition to renewable energy requires a concertedeffort from governments, the private sector, and the public, but the rewards are worth the investment.**解决能源危机的关键：开发新能源**面对即将到来的能源危机，世界正站在十字路口。

关于怎样节能的英语作文Title: Embracing Energy Efficiency: A Call to Action.In today's world, the need for energy is constant and ever-growing. However, the traditional methods of generating energy often come with significant environmental costs. This is why energy efficiency has become a crucial aspect of sustainable development. Energy efficiency not only reduces the carbon footprint but also leads to cost savings and resource conservation. In this article, we will explore various strategies and practices that can help us embrace energy efficiency in our daily lives.Firstly, let's understand what energy efficiency means. Energy efficiency refers to the use of less energy to provide the same level of service or produce the same amount of goods. In essence, it is about making the most of the energy we consume. This can be achieved through various means, such as improving the efficiency of appliances, optimizing building design, and adopting renewable energysources.One of the most effective ways to improve energy efficiency is through the use of energy-efficient appliances. These appliances are designed to consume less energy while delivering the same level of performance. For instance, energy-efficient refrigerators, air conditioners, and lighting systems can significantly reduce electricity consumption in households and commercial spaces. Switching to these appliances is a simple yet impactful step towards energy conservation.Another crucial aspect of energy efficiency is building design. Well-designed buildings can reduce energy consumption by up to 50%. This is achieved through techniques such as proper insulation, efficient heating and cooling systems, and the use of renewable energy sources like solar panels. By prioritizing energy efficiency in building design, we can create sustainable structures that contribute to reducing the overall energy demand.Adopting renewable energy sources is another keystrategy for improving energy efficiency. Renewable energy sources, such as solar, wind, and hydroelectric power, are clean and renewable. They do not emit greenhouse gases or contribute to air pollution. Transitioning to renewable energy not only helps reduce our carbon footprint but also ensures energy security by diversifying our energy supply.Individual actions also play a crucial role in energy efficiency. Simple habits like turning off lights and electronic devices when not in use, using public transportation or cycling instead of private vehicles, and insulating our homes can significantly reduce energy consumption. Furthermore, we can also support energy-efficient practices by purchasing energy-efficient products and appliances, and demanding energy-efficient solutions from our governments and businesses.Governments and businesses also have a crucial role to play in promoting energy efficiency. Governments can implement policies and regulations that encourage the use of energy-efficient technologies and practices. They can also provide incentives and subsidies to encourageindividuals and businesses to adopt energy-efficient solutions. Businesses can contribute by adopting energy-efficient practices and technologies, investing in research and development to create more efficient products, and educating their employees about energy efficiency.In conclusion, energy efficiency is crucial for sustainable development and environmental protection. It requires a concerted effort from individuals, businesses, and governments to achieve the desired results. By embracing energy efficiency in our daily lives, we can contribute to reducing carbon emissions, conserving resources, and creating a more sustainable future for ourselves and our planet. Let's take action today and embrace energy efficiency.。

Green chemistry,also known as environmentally benign chemistry,is a philosophy of chemical research and engineering that seeks to reduce or eliminate the use and generation of hazardous substances.This approach is essential in todays world,where environmental concerns are at the forefront of scientific and industrial practices.Heres a detailed essay on green chemistry in English:Title:The Importance of Green Chemistry in Modern SocietyIntroductionIn the21st century,the concept of sustainability has become integral to various fields, including chemistry.Green chemistry,as a branch of sustainable science,aims to design products and processes that minimize the environmental impact while enhancing efficiency.This essay will explore the principles of green chemistry,its applications,and the significance of integrating this philosophy into our daily practices.Principles of Green ChemistryThe twelve principles of green chemistry,as outlined by Paul Anastas and John Warner, serve as a guide for chemists to develop safer and more environmentally friendly processes:1.Prevention:It is better to prevent waste than to treat or clean up waste after it is created.2.Atom Economy:Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.3.Less Hazardous Chemical Syntheses:Wherever practicable,synthetic methods should be designed to use and generate substances with little or no toxicity to human health and the environment.4.Designing Safer Chemicals:Chemical products should be designed to affect their desired function while minimizing their toxicity.5.Safer Solvents and Auxiliaries:The use of auxiliary substances e.g.,solvents, separation agents should be made unnecessary wherever possible and innocuous when used.6.Design for Energy Efficiency:Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized.e of Renewable Feedstocks:A raw material or feedstock should be renewable rather than depleting wherever technically and economically practicable.8.Reduce Derivatives:Unnecessary derivatization use of blocking or protecting groups, temporary modification of physical/chemical processes should be minimized or avoided if possible.9.Catalyst:Catalytic reagents are superior to stoichiometric reagents.10.Design for Degradation:Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.11.Realtime Analysis for Pollution Prevention:Analytical methodologies need to be further developed to allow for realtime,inprocess monitoring and control prior to the formation of hazardous substances.12.Inherently Safer Chemistry for Accident Prevention:Substances and the form of a substance used in a process should be chosen to minimize the potential for chemical accidents,including releases,explosions,and fires.Applications of Green ChemistryGreen chemistry is applied across various industries,including pharmaceuticals, agriculture,and manufacturing.For instance,in pharmaceuticals,green chemistry principles are used to develop drugs with fewer side effects and reduced environmental impact.In agriculture,green chemistry is employed to create biodegradable pesticides and fertilizers,reducing soil and water pollution.Significance in Modern SocietyThe integration of green chemistry into modern society is crucial for several reasons:Environmental Protection:It helps in reducing pollution and preserving natural resources. Health Benefits:By minimizing the use of hazardous chemicals,green chemistry contributes to a healthier environment for humans and wildlife.Economic Benefits:Green chemistry can lead to cost savings through the reduction of waste treatment and disposal costs.Regulatory Compliance:It helps industries meet environmental regulations and avoid potential legal issues related to pollution.ConclusionGreen chemistry is not just a scientific endeavor but a societal necessity.As we move towards a more sustainable future,the adoption of green chemistry practices is imperative. By embracing these principles,we can ensure a cleaner,healthier,and more prosperous world for generations to come.RecommendationsTo further promote green chemistry,educational institutions should incorporate it into their curricula,and industries should invest in research and development for ecofriendly processes.Additionally,governments should provide incentives for businesses that adopt green chemistry practices and enforce regulations that discourage the use of harmful chemicals.In conclusion,green chemistry represents a proactive approach to environmental stewardship,aligning with the global movement towards sustainability.It is a philosophy that,when embraced,can lead to a more harmonious coexistence between human activities and the natural world.。

能源效率英语：Energy efficiency英[ˈenədʒi ɪˈfɪʃnsi]慢美[ˈenərdʒi ɪˈfɪʃnsi]Energy efficiency;EER;PUE;COP例句：基于超效率DEA的能源效率评价模型研究Evaluation Model of Energy Efficiency Based on Super-Efficiency-DEA基于DEA方法的全要素能源效率分析DEA-based research on total factor energy efficiency政策情景包括提高能源效率、能源结构调整、实施SO2排放总量控制等。

Those policies include energy efficiency improvement, energy switch from coal to natural gas, SO2 emission control target etc.全要素能源效率的DEA模型评价&基于中国1991～2007年数据的实证检验Evaluation for the DEA Model in Calculating Total-Factor Energy Efficiency An Empirical Test Based on China's Data from 1991 to 2007在中国实施CO2减排政策将有助于能源效率的提高，但同时也将对中国经济增长和就业带来负面影响。

The conclusions are that the carbon abatement policy in China would benefit energy efficiency improvement, but would have negative impacts on China economic growth and employment.。

Addressing Energy Shortages: A Multifaceted ApproachIn the face of mounting global challenges, energy shortages have emerged as a pressing concern that demands immediate attention and innovative solutions. The consequences of inadequate energy supplies extend far and wide, impacting economic growth, social welfare, and environmental sustainability. To effectively tackle this issue, a multifaceted approach is necessary, encompassing diversification of energy sources, promotion of energy efficiency, investment in renewable technologies, and fostering international cooperation.Firstly, diversifying our energy mix is crucial. Reliance on a single or few energy sources, particularly fossil fuels, exacerbates vulnerability to supply disruptions and price volatility. By exploring and developing alternative energy resources such as nuclear, solar, wind, and hydroelectric power, we can create a more resilient energy system. This diversification not only reduces the risk of shortages but also aligns with the goal of transitioning to a low-carbon economy.Secondly, promoting energy efficiency is a high-impact strategy. Enhancing the efficiency of energy use across sectors—from industrial processes to household appliances—can significantly reduce demand and alleviate pressure on energy supplies. Governments can play a pivotal role by implementing policies that encourage energy-efficient practices and technologies, such as providing subsidies for green building projects or setting mandatory efficiency standards for products.Thirdly, investing in renewable energy technologies is paramount. Renewables offer a sustainable and scalable solution to energy shortages. Advancements in solar panels, wind turbines, and battery storage technologies have made renewable energy more competitive and accessible. Governments and private sectors must collaborate to scale up research and development, facilitate financing mechanisms, and streamline regulatory processes to accelerate the deployment of renewable energy projects.Furthermore, fostering international cooperation is vital. Energy shortages are a global challenge that requires collective action. Countries can collaborate on cross-border energy infrastructure projects, share best practices in energy management, and coordinate efforts to mitigate climate change, which indirectly contributes to energy security by promoting sustainable energy sources.Lastly, public awareness and engagement are essential components of any comprehensive strategy. Educating citizens about energy conservation, the benefits of renewable energy, and the importance of energy security can inspire individual actions that, when multiplied across populations, lead to substantial impacts.In conclusion, addressing energy shortages necessitates a comprehensive andintegrated approach that combines diversification of energy sources, promotion of energy efficiency, investment in renewable technologies, international cooperation, and public engagement. By pursuing these strategies in concert, we can pave the way for a more secure, sustainable, and prosperous energy future.。

解决能源问题的方法英语作文英文回答：Addressing the energy issue necessitates a multifaceted approach that includes adopting renewable energy sources, enhancing energy efficiency, and promoting energy conservation. Renewable energy sources, such as solar, wind, geothermal, and biomass, offer sustainable and environmentally friendly alternatives to fossil fuels. However, their intermittency requires the development of efficient energy storage systems.Energy efficiency measures involve optimizing energyuse in buildings, industries, and transportation. These include improving insulation, using energy-efficient appliances, and implementing energy management systems. Additionally, promoting energy conservation through public awareness campaigns and behavioral changes cansignificantly reduce energy consumption.Another critical aspect is investing in research and development for technological advancements in clean energy. This includes exploring new renewable energy sources, improving energy storage capabilities, and developing more efficient energy utilization technologies. International cooperation and knowledge sharing among nations can accelerate progress and drive innovation in the energy sector.中文回答：解决能源问题的途径。

如何解决能源问题英语作文120字英文回答：Energy is a major concern for many countries around the world. As the population grows and the economy develops, the demand for energy increases. This has led to a number of challenges, including:The need to find new sources of energy: As fossilfuels become more scarce and expensive, we need to find new ways to generate energy. This includes renewable energy sources such as solar, wind, and geothermal energy.The need to reduce our dependence on fossil fuels: Fossil fuels are a major source of greenhouse gases, which contribute to climate change. We need to reduce ourreliance on fossil fuels in order to protect the environment.The need to improve energy efficiency: We can alsoreduce our energy consumption by improving the efficiencyof our homes, businesses, and transportation systems.There are a number of different approaches that can be taken to address the energy crisis. These include:Investing in renewable energy: Renewable energysources are becoming increasingly cost-effective. Investing in renewable energy can help to reduce our dependence on fossil fuels and protect the environment.Improving energy efficiency: We can also reduce our energy consumption by improving the efficiency of our homes, businesses, and transportation systems. This can be done by using more efficient appliances, insulating our homes, and driving less.Promoting energy conservation: Energy conservation is another important way to reduce our energy consumption.This can be done by turning off lights when we leave a room, unplugging appliances when we're not using them, andwalking or biking instead of driving whenever possible.By taking these steps, we can help to address the energy crisis and create a more sustainable future.中文回答：解决能源问题的办法有很多，包括：投资可再生能源，可再生能源成本越来越低，投资于可再生能源可以帮助减少我们对化石燃料的依赖，并保护环境。

Energy efficiency of elevated water supply tanks for high-rise buildingsC.T.Cheung,K.W.Mui,L.T.Wong ⇑Department of Building Services Engineering,The Hong Kong Polytechnic University,Hong Kong,Chinah i g h l i g h t s"We evaluate energy efficiency for water supply tank location in buildings."Water supply tank arrangement in a building affects pumping energy use."We propose a mathematical model for optimal design solutions."We test the model with measurements in 22Hong Kong buildings."A potential annual energy saving for Hong Kong is up to 410TJ.a r t i c l e i n f o Article history:Received 16April 2012Received in revised form 2October 2012Accepted 19October 2012Available online xxxx Keywords:BuildingWater supply Energy efficiency Water consumption Storage tank locationa b s t r a c tHigh-rise housing,a trend in densely populated cities around the world,increases the energy use for water supply and corresponding greenhouse gas emissions.This paper presents an energy efficiency eval-uation measure for water supply system designs and a mathematical model for optimizing pumping energy through the arrangement of water tanks in a building.To demonstrate that the model is useful for establishing optimal design solutions that integrate energy consumption into urban water planning processes which cater to various building demands and usage patterns,measurement data of 22high-rise residential buildings in Hong Kong are employed.The results show the energy efficiency of many existing high-rise water supply systems is about 0.25and can be improved to 0.26–0.37via water storage tank relocations.The corresponding annual electricity that can be saved is 160–410TJ,a 0.1–0.3%of the total annual electricity consumption in Hong Kong.Ó2012Elsevier Ltd.All rights reserved.1.IntroductionHigh-rise housing development,a trend in densely populated cities around the world,increases water supply energy consump-tion.A study of pumping energy use in urban water supply systems showed that the average energy consumption in residential build-ings equaled 45%of the total pumping energy needed to deliver water from the treatment plants to households [1].In Hong Kong,a developed city on the hilly terrain with limited usable land for buildings,very tall buildings are a trend in recent developments.Indeed,many newly constructed government-funded residential buildings are over 40storeys or over 100m and the current average residential building height in the city is estimated to be 25.8storeys [2].The total annual water consump-tion is about 1200Mm 3year À1(i.e.the per capita daily consump-tion is 408L day À1),and it will grow to 1315Mm 3year À1by 2030[3].Correspondingly,water supply systems in buildings account for approximately 1.6%of the total city electricity use according to the expression below,where E pump is the energy use for pumping a volumetric water demand v pump ,N B (=25.8storeys)is the average building height,constants 3.6and 60accounts for unit conversion,one indicates additional pump lift of one storey height over the building’s topmost floor,and 1.2is a lumped value for pump and motor efficiencies,pipe friction and building storey height respectively [1].E pump ¼3:6Â1:2ðN B þ1Þv pump60ð1ÞAs the water pressure head at the government water mains in Hong Kong is insufficient to reach the topmost appliances in almost all high-rise buildings,gravity storage tanks on building rooftops (or on intermediate mechanical floors)are designed for distributing water through down feed pipes [4].To minimize the problems of water leakage or damage in supply pipes and appliances caused by excessive water pressure on lower floors in low demand situations,proper working pressure limits (e.g.100–450kPa)can be maintained using pressure reducing valves (PRVs).PRVs with adjustable settings and screwed joints are commonly installed to maximize application flexibility.0306-2619/$-see front matter Ó2012Elsevier Ltd.All rights reserved./10.1016/j.apenergy.2012.10.041⇑Corresponding author.Tel.:+852********;fax:+852********.E-mail addresses:behorace@.hk (K.W.Mui),beltw@.hk (L.T.Wong).Although energy efficiency is a major concern for sustainablehigh-rise developments,there is no existing measure that system-atically addresses the issue with respect to the optimal design and operation of high-rise water supply systems.Design solutions which integrate effective energy use into water planning process should be developed so as to save energy,reduce waste and protect our environment [5,6].This paper proposes an energy efficiency evaluation measure for water supply system designs in buildings.Verification measurements in some high-rise residential buildings of Hong Kong are used to demonstrate the applicability of the eval-uation model.Energy performance targets for some system de-signs,together with estimated energy savings potential are also derived.2.Energy efficiency of building water supply systemsWater supply by an elevated reservoir over a town is used in practice.This idea has been commonly adopted in buildings by locating a roof tank.However,the two systems are not identical in terms of energy efficiency.Fig.1illustrates these two water sup-ply system designs:(a)an elevated water tank that feeds demands with little height differences (e.g.an elevated water tower over a town);(b)a roof tank that feeds distributed demands with large height differences (e.g.a roof tank on top of a building).For a high-rise building,the system design is characterized by the waterlift demand height ratio h Ãl given by Eq.(2),where (h n Àh 1)is the height difference between the demands at the top and bottom for demand height i =1,2,...,n and h l is the water lift height.h Ãl ¼h n Àh 1h lð2ÞThe water lift height h l is the sum of the height measured from the tank base to the tank inlet h c –approximated by the tank volume V c ,the height difference between the demand n and the tank base h b ,and the height difference between the water surface (i.e.of the res-ervoir in design (a)or of the break tank in design (b))and the top demand location hn ,Nomenclature A area (m 2)C constant head pressure E energy (MJ)E a ,E d annual energy (MJ year À1),daily energy (MJ day À1)g gravity (=9.81ms À2)H pressure head of water column (m of H 2O)h height (m)i ,j building floor counts,i ,j =1,2,...,n N number countO occupant area ratio (ps m À2)V volume (m 3)vvolumetric water demand over a specified period (m 3)a energy efficiencyg c overall transmission efficiency g e electric motor efficiencyg m mechanical transmission efficiency g ppump efficiency#random number between 0and 1qwater density (=1000kg m À3)Subscript 0of reference1,2,...,n of demands 1,2,...,n ,from the bottom floor to the topfloorI ,II of cases I and II a of annuallyB of building storey b of water tank basec of water tank base to inletd of dailyf of friction in upfeed water pipe ff of floor to floor L of lower zone l of water lift o of outlet out of outputpump of water pump s of occupant U of upper zone %ofpercentageSuperscript $of distribution Ãof relative‘of improvement2 C.T.Cheung et al./Applied Energy xxx (2012)xxx–xxxh l ¼h c þh b þh n ;h c $V 1=3cð3ÞThe water lift demand height ratios for system designs (a)and (b)are h Ãl ¼0and h Ãl >0respectively.For a high-rise building,the ratio h Ãl $1is dominated by the demand heights h l $h n and h b +h c (h n .The desired minimum water pressure head H o ,say 5m (H 2O)in some design practices,is assumed at the demand point and the friction head required in the upfeed water pipe H f is taken as a por-tion of the pipe length (i.e.10%of h l )[7],H o ¼5;H f ¼0:1h l ð4ÞConsider the case of uniformly distributed demands along the building height (i.e.v 1=v 2=...=v i =v n =v ),the demand heights h i ,where i =1,2,...,n ,for the two designs (a)and (b)are expressed by,h Ãl ¼0:h 1¼h 2¼...¼h nh Ãl >0:h 2Àh 1¼h 3Àh 2¼...¼h n Àh n À1¼C ff(ð5ÞE out ,(MJ)the potential energy for the water demands at height h i (i.e.‘output energy’of a design)is given below,where q (=1000kg m À3)is the water density and g (=9.81ms À2)is the gravity,8h Ãl :E out ¼q gXiv i h i ;i ¼1;2;...;n ð6ÞIt can be rewritten for both designs,h Ãl ¼0:E out ¼q gn v h nh Ãl >0:E out ¼q gn v h 1þh n8<:ð7ÞThe ‘input energy’of both designs is the pumping energy of liftingwater up to the tank E pump (MJ)as defined below,where g c is the de-sign overall transmission efficiency,8h Ãl :E pump ¼q gn v h l g c ¼q gn v ðH o þH f þh n þh b þh c Þg cð8ÞEnergy efficiency,which is the ‘output energy’divided by the ‘inputenergy’,is a measure of pumping energy performance.It can be determined for the water supply systems using the heights,pipe friction and allowable pressure head,a ¼E outE pump;h Ãl ¼0:a ¼h n g c 5þ1:1ðh n þh b þh c Þh Ãl>0:a ¼h 1þh n2 g c 5þ1:1ðh n þh b þh c Þ8>>>><>>>>:ð9ÞTable 1exhibits some example design parameters for building water supply systems.A top demand height h n P 10m,i.e.a height of three storeys,was chosen for illustration.The design overall transmission efficiency g c (34–62%)accounted for 50–80%of the pump efficiency g p ,about 90–100%of the mechanical transmission efficiency g m accounting the power transmission between the mo-tor and pump,and 70–90%of the electricity motor efficiency g e [8].For simplicity,constant efficiencies are assumed:g p =0.65,g m =0.9,g e =0.9,and g c =0.5625,g c ¼g p g m g eð10ÞAccording to Fig.2,the values of energy efficiency a for water sup-ply system designs of h Ãl between 0and 1using the design numbersin Table 1are approaching 0.5and 0.25for h Ãl ¼0and h Ãl >0respec-tively with an increased height h n .h Ãl ¼0:a ¼g c h n5þ1:1h n þ13ðÞ¼g c h n19:3þ1:1h nh Ãl >0:a ¼g ch n þ12ÀÁn ¼g c h n þ1ðÞn8>>><>>>:ð11Þh n !1:h Ãl ¼0:a $g c$0:5h Ãl >0:a $g c$0:25(ð12ÞIt is noted that for a residential building height of up to 300m inHong Kong,the energy efficiency values are 0.44and 0.24for de-signs (a)and (b).The design parameters h b ,h c ,h n ,H o have signifi-cant contributions to the energy efficiency.3.Water demand modelA water demand model below is adopted to calculate the daily water consumption at height in Eq.(6)for the optimization of stor-age tank location(s).The average daily water consumption on a floor v i ,d is determined by Eq.(13),where N s ,i is the number of occupants on floor i ,v s ,d is the average daily per-capita water con-sumption,O s ,i is the occupant area ratio on floor i and A i is the total apartment area on floor i [9],v i ;d ¼N s ;i v s ;d ;N s ;i ¼O s ;i A i ð13ÞA number of studies approximated the surveyed regional profiles ofoccupant area ratio O s ,hourly occupant load variations in weekdays and holidays and average daily per-capita water consumption v s ,d in buildings by parametric distribution functions as shown in Table 1[10,11].Parameters v s ,d and O s ,i in Eq.(13)can be determined via Monte Carlo simulations at percentile v s ,d ,O s ,i =#e [0,1]throughthe distribution functions ~vs ;d and ~O s ,where #is a random number Table 1Selected number of design parameters for building water supply systems.Pump efficiency g p0.65Mechanical transmission efficiency g m 0.90Electric motor efficiency g e0.90Total water storage tank volume V c (m 3)27Height between tank base and the last demand location h b (m)10Height of the bottom demand location h 1(m)1Height of the top demand location h n (m)P 10Height of the tank inlet measured from tank base h c (m)3Friction head loss in pipes H f (m)0.1h l Minimum water pressure head allowed at the outlet H o (m)5Occupant area ratio O s (ps m À2)[10](public residential)0.085(0.03)(Private residential)0.096(0.04)Yearly per-capita water consumption (m 3ps À1year À1)[9,11](freshwater)70(13)(Seawater)22(10)Standard deviation shown inbrackets.C.T.Cheung et al./Applied Energy xxx (2012)xxx–xxx3taken from a pseudo random number set generated by the prime modulus multiplicative linear congruential generator [12].The pseudo set has been applied in a number of engineering applica-tions with reasonable predictions made [13,14].Z v s ;dÀ1~vs ;d d v s ;d ¼#2½0;1 ;ZO s ;iÀ1~Os dO s ¼#2½0;1 ;v s ;d 2~vs ;d ;O s ;i 2~O s ð14ÞThe total (daily)water consumption is used to calculate the pump-ing energy input to a building water supply system,n v d ¼X n i ¼1v i ;d ;E pump ¼q gh lP ni ¼1v i ;dg cð15Þ4.SurveyA survey of 22government-funded residential buildings in Hong Kong (Table 2)was used to examine the validity and applica-bility of the proposed water demand model and the energy effi-ciency measure.It was noted that the apartments were rented to lower-income families.In each of the sampled buildings,water secured from the city mains was stored in a break tank and transferred through a pair of transfer pumps to the rooftop gravity tanks for distribution to every floor of the building.There are two separated water supply networks in Hong Kong –one for fresh water supply and the other for seawater flushing;only one old building was using freshwater for water closet flushing and had no separate flushing water tank.The buildings varied from 15to 40storeys,with an average height of 29storeys.Number of apartments,apartment floor area,roof tank volumes and demand heights of all buildings are summa-rized in Table 2.Demand distributions in some buildings were ver-tically uneven as indicated through the number and size of apartments.The heights of bottom demand (h 1)were below 5m,except for Building 2(27.6m)and Building 18(15.7m).The data of height difference between the tank base and the top demand (i.e.hb )were 10m or less,except for Buildings 3(12m),4(11.5m)and 18(14.5m).Heights between any two (vertically)consecutive demands were about 2.7m.5.Survey resultsIn the surveyed buildings,electricity energy use was metered continuously for 24h for all water supply pumps to determine the total daily pumping energy (input energy to the system)con-sumption as presented in Table 2.It was noted that a single-day energy consumption monitoring period might fall between two roof tank filling cycles i.e.,cases of empty roof tank or full tank,and the corresponding energy to fill-up the roof tank can be taken as the error of energy estimates.In this study,the probable errors of measurement were taken at a half of this error and indicated as error bars in Fig.3.Fig.3shows the predicted daily pumping energy consumption against the measured one for the surveyed buildings.The predic-tions,which were based on typical pump efficiency details dis-played in Table 1,reasonably agreed with the measurementTable 2Survey of 22residential buildings in Hong Kong.No.Storeys N sApartments per storeyApartment floor area HeightTank volume V c (m 3)Measured daily pumping energy E d,pump (MJ)Energy efficiency a(m 2)h 1(m)h n (m)h b (m)h l (m)Fresh water Flushing water Roof tank only(I)One tank per floor (II)Oneintermediate tank 1381817–42 4.6104.59.8118492710430.240.350.282381817–4927.6126.69.0139502713090.280.360.323402017–42 4.6109.912.012653279180.240.350.2844018–2516–49 4.6109.911.5125582710680.230.350.285402017–42 4.6109.99.512355279340.240.350.286361832–49 4.599.0 6.5109552714220.240.340.277261717–49 4.271.7 5.48026175160.240.310.2682615–2516–49 4.271.7 5.48036126670.230.310.269402017–42 4.6109.99.012354279860.240.350.2810173321 3.044.7 2.6501802300.240.270.2411203321 3.252.4 2.65836535640.240.280.2412183321 3.647.8 2.95556272610.240.270.2413186121 4.248.4 2.95680384980.240.270.2414273033–44 4.672.2 2.97820136370.250.310.2615251534–63 3.666.07.87616173450.230.300.2616271533–44 3.671.2 5.58023133690.240.310.2617233439–5115.772.9 5.98226266290.280.310.3018401033–56 4.0111.314.512929143790.230.350.2819461033–56 4.5128.310.314229155000.240.370.2820191634–54 3.651.7 5.26016113180.230.270.2521232233–53 3.662.3 6.37233.516.34240.230.300.2522353627 3.892.27.7104794712640.240.330.274C.T.Cheung et al./Applied Energy xxx (2012)xxx–xxxresults.The predicted average daily water consumption of a floor v i ,d at height h i was used to determine the output energy E out (Eq.(6))for the buildings and thus the energy efficiency of existing roof tank design as shown in Table 2.Fig.4plots the energy efficiency against the top demand height,with cases h Ãl ¼0and h Ãl >0shown for comparison.As expected in roof tank designs,energy efficiency values obtained for the sur-veyed buildings were close to the lower side of h Ãl $1:A few caseswere found below h Ãl $1for two reasons:(1)demands were un-evenly distributed and dominated by more occupants on lower floors (Buildings 4and 8),(2)there was an excessive height differ-ence between the tank base and the tank inlet (h b ;Buildings 3and 18).Buildings 2and 17,in which the bottom demand locations (h 1)were higher,gave higher energy efficiency ($0.28).6.Application and energy implicationsThe energy efficiency of a high-rise building can be optimized by the proper arrangement of water storage tank(s).Two example designs are illustrated below:6.1.One supply tank for each demand heightAn individual tank is reserved for every floor (h Ãl ¼0)in a build-ing.Based on the data in Table 1,the energy efficiency a I is given by the average energy efficiency of all individual floors,a I $1h n Àh 1Z h nh 1h n34:3þ1:96h ndh n¼1h n Àh 1h n1:96À8:93ln ð34:3þ1:96h n Þ!h nh 1;h 1P 0ð16Þor expressed in discrete function,assuming floor-to-floor height,C ff ,is constant.a I $1n X n i ¼1h i34:3þ1:96h i;h 1P 0ð17ÞThe calculated values of a I for the 22surveyed buildings using this arrangement are shown in Table 2and Fig.4.The arrangement offers energy efficiency improvements ranging from 11%to 55%.The energy efficiency improvement a 0(in percentage a 0%)is ex-pressed by,a 0¼a I Àa h Ãl >0;a 0%¼a I a h Ãl >0À1!Â100%ð18ÞIt is noted that using more riser pipes in this arrangement causes energy loss and energy may not be saved for top demand height hn <20m.However,the improvement becomes significant forgreater h n , e.g.a 0%¼46%and 73%for h n =100m and 200m respectively.6.2.One roof tank and one intermediate tankDemands v at height h in an n -storey building are subdivided on the j th floor and zoned vertically into the upper (U )and lower (L )zones,where C ff is the floor-to-floor height,v ¼f v 1;v 2;...;v j g L ;f v j þ1;v j þ2;...;v ng U ;h¼f h 1;h 2;...;h j g L ;f h j þ1;h j þ2;...;h n g U ð19Þh j ¼h 1þðj À1ÞC ff ;h j þ1¼h j þC ff ;h n ¼h 1þðn À1ÞC ffð20ÞCorrespondingly,the energy output E out is,E out ;L¼q g X j i ¼1v i h i ¼q gj v h 1þðj À1ÞC ff E out ;U¼q g X n i ¼j þ1v i h i ¼q g ðn Àj Þv h 1þðn þj À1ÞC ff 2 8>>>>><>>>>>:ð21ÞThe water tank size is assumed proportional to the demands andthe height of tank inlet h c is given by,h c ;L ¼ffiffiffiffiffiffiffiffiffiffiffiffiV c j =n 3p h c ;U¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffið1Àj =n ÞV c3p (ð22ÞThe energy input E pump is,E pump ;L ¼q gj v ðH o þH f ;L þh 1þðj À1ÞC ff þh c ;L þh b Þg cEpump ;U¼q g ðn Àj Þv ðH o þH f ;U þh 1þðn À1ÞC ff þh c ;U þh b Þg c8<:ð23ÞThe energy efficiency a is,a L ¼h 1þðj À1ÞCff 2ðH o þH f ;L þh 1þðj À1ÞC ff þh c ;L þh b Þgc¼g c ð2h 1þðj À1ÞC ff Þ2ðH o þ1:1ðh 1þðj À1ÞC ff þffiffiffiffiffiffiffiffiV c j =n 3p þh b ÞÞa U ¼h 1þðn þj À1ÞC ff 2o f ;U 1ff c ;U b g c¼g c ð2h 1þðn þj À1ÞC ff Þ2ðH o þ1:1ðh 1þðn À1ÞC ffþffiffiffiffiffiffiffiffiffiffiffiffiffiffiffið1Àj =n ÞV c 3p þhb ÞÞ8>>>><>>>>:ð24ÞThe overall energy demand efficiency is determined by,a II ¼a L j =n þa U ð1Àj =n Þð25ÞThis arrangement offers energy efficiency improvements a 0%of 1–24%as exhibited in Table 2.Fig.5graphs the energy efficiency ranges of this arrangement for a building when h 1=4.2m,V c =40m 3,and n =20(0.21–0.26),40(0.23–0.28),60(0.25–0.29)and 80(0.25–0.3).As there are additional pipe frictions in the sep-arated piping networks,no significant energy savings can be achieved when the intermediate tank is close to the roof or the low-est floor.The optimal height for zoning is about the middle height of the building,i.e.j $n /2.Fig.6,in which a building height of 25.8storeys (current average residential building height in Hong Kong)is highlighted,shows the annual energy output (E a ,out )for the water demands against building height,and the corresponding annual en-ergy input (E a ,pump )for the roof tank systems with energy efficiency values a in between 0.25and 0.45.It can be seen that the energy consumption is proportional to building height.For the height of 25.8storeys,E a ,out is 456TJ and corresponds to an energy input of 1822TJ (1.2%of Hong Kong’s total electricity consumption (149366TJ))at a =0.25(of only roof tank arrangement).Fig.7de-picts the potential energy savings through efficiency improvements a 0.It demonstrates that the potential annual energy that can be saved for Hong Kong is 410TJ (a 0=0.06)if design arrangement (I)is adopted or 160TJ (a 0=0.02)if design arrangement (II)is taken up.C.T.Cheung et al./Applied Energy xxx (2012)xxx–xxx 57.ConclusionEnergy efficiency in buildings is a sustainable development strategy in Hong Kong.It is necessary to develop a method to sys-tematically address energy efficiency with respect to the optimal design of high-rise water supply systems.This paper presented an energy efficiency evaluation measure for water supply system designs and developed a mathematical model for optimizing pumping energy through the arrangement of water tanks in a building.The model was demonstrated to be useful for establishing optimal design solutions that integrate energy consumption into urban water planning processes which cater to various building demands and usage patterns.The results showed that the energy efficiency of many existing high-rise water supply systems was about 0.25and could be improved to 0.26–0.37via water storage tank relocations.The corresponding annual electricity that could be saved was 160–410TJ,a 0.1–0.3%of the total annual electricity consumption in Hong Kong.AcknowledgementThe work described in this paper was partially supported by a grant from the Research Grants Council of the HKSAR,China (PolyU533709E).References[1]Cheng CL.Study of the inter-relationship between water use and energyconservation for a building.Energy Build 2002;34(3):261–6.[2]Cheng CL,Yen CJ,Wong LT,Ho KC.An evaluation tool of infection risk analysisfor drainage system in high-rise residential buildings.Build Serv Eng Res Technol 2008;29(3):233–48.[3]Hong Kong Water Supplies Department.Total water management in HongKong:towards sustainable use of,water resources;2008.6 C.T.Cheung et al./Applied Energy xxx (2012)xxx–xxx[4]Wong LT,Mui KW.Modeling water consumption and flow rates for flushingwater systems in high-rise residential buildings in Hong Kong.Build Environ 2007;42(5):2024–34.[5]Mui KW,Wong LT,Hui KW.Downtime of in-use water pump installations forhigh-rise residential buildings.Build Serv Eng Res Technol 2012;33(2):181–90.[6]Wong LT,Mui KW.Stochastic modelling of water demand by domesticwashrooms in residential tower blocks.Water Environ J 2008;22(2):125–30.[7]Plumbing Services Design Guide,2nd ed.England,Hornchurch:The Institute ofPlumbing;2002.[8]Kaya D,Yagmur EA,Yigit KS,Kilic FC,Eren AS,Celik C.Energy efficiency inpumps.Energy Convers Manage 2008;49(5):1662–73.[9]Wong LT,Mui KW.Epistemic water consumption benchmarks for residentialbuildings.Build Environ 2008;43(6):1031–5.[10]Wong LT,Mui KW.An epistemic analysis of residential occupant load factor.In:Proceedings of Zhejiang-Hong Kong joint symposium 2007–innovative building design and technology-challenges of climate change,6–7July.Hangzhou,China;2007.p.38–44.[11]Wong LT,Liu WY.Demand analysis for residential water supply systems inHong Kong.HKIE Trans 2008;15(2):24–8.[12]Park SK,Miller KW.Random number generators:good ones are hard to find.Commun ACM 1988;31(10):1192–201.[13]Wong LT,Mui KW.Efficiency assessment of indoor environmental policy forair-conditioned offices in Hong Kong.Appl Energy 2009;86(10):1933–8.[14]Wong LT,Mui KW,Guan Y.Shower water heat recovery in high-rise residentialbuildings of Hong Kong.Appl Energy 2010;87(2):703–9.C.T.Cheung et al./Applied Energy xxx (2012)xxx–xxx7。

节能减排建议英语作文Title: Strategies for Energy Conservation and Emission Reduction。

In the face of the pressing issue of climate change, it has become imperative for individuals and societies alike to adopt measures for energy conservation and emission reduction. This essay explores various strategies that can be implemented to address this global challenge.First and foremost, enhancing energy efficiency across all sectors is crucial. This can be achieved through technological advancements such as improved insulation in buildings, energy-efficient appliances, and the adoption of renewable energy sources like solar and wind power. By reducing energy wastage and transitioning to cleaner sources, significant reductions in greenhouse gas emissions can be realized.Additionally, promoting sustainable transportation isessential in reducing carbon emissions. Encouraging the use of public transportation, carpooling, biking, and walking can significantly decrease reliance on fossil fuels for transportation. Furthermore, investing in electric vehicles and expanding the infrastructure for charging stations can accelerate the transition towards a low-carbon transportation system.Another key aspect of energy conservation is raising awareness and fostering a culture of sustainability. Educating individuals about the environmental impact of their actions and empowering them to make eco-friendly choices can lead to widespread behavioral changes. This can range from simple practices such as turning off lights when not in use to more significant lifestyle changes like adopting a plant-based diet, which has a lower carbon footprint compared to meat production.Furthermore, policies and regulations play a crucial role in driving energy conservation and emission reduction efforts. Governments can implement measures such as carbon pricing, subsidies for renewable energy projects, andstringent emissions standards for industries. By creating a conducive regulatory environment, policymakers can incentivize businesses and individuals to prioritize sustainability in their operations and daily lives.Moreover, fostering innovation and research in clean energy technologies is paramount. Investing in research and development can lead to breakthroughs in renewable energy generation, energy storage, and carbon capture technologies. By harnessing the power of innovation, we can acceleratethe transition towards a sustainable energy future and mitigate the impacts of climate change.In conclusion, combating climate change requires concerted efforts from all sectors of society. By implementing strategies such as enhancing energy efficiency, promoting sustainable transportation, raising awareness, enacting supportive policies, and fostering innovation, we can make significant strides towards energy conservationand emission reduction. It is imperative that we actswiftly and decisively to safeguard the planet for futuregenerations. Together, we can build a more sustainable and resilient world.。