Trabalho Energia Renovavel

Contents Question 13 Question 27 Question 310 Conclusion15 Marking Criteria16 References17 Table of Figures Figure 1 Tarraleah Power Station Hydro Tasmania 202011 Question 1 Los Angeles has a latitude and longitude of approximately 340549 N and 1182426 W respectively Los Angeles is in a time zone that is 7 hours behind GMT GMT7 during summer and 8 hours behind GMT GMT8 during winter Assume YBD is your birthday 01 Jan A Find the angle between the beam and the normal to the collectors surface at 10 am on BD if the collector is orientated towards the equator and it has a slope of 30 On January 1st in Los Angeles latitude 3405N we want to calculate the angle between the incoming solar beam and the collectors normal at 10 AM The collector is tilted at 30 and faces the equator azimuth 0 Using the standard solar angle formula Twidell Weir Eq 28 we first calculate the declination for January 1st as The hour angle at 10 AM is By applying the expanded incidence angle formula and substituting values for latitude slope and azimuth the result is Answer The angle between the beam radiation and the collectors normal at 10 AM is approximately 241 degrees B Estimate sunrise and sunset times on YBD To estimate the sunrise and sunset times on January 1st we calculate the sunrise hour angle ωₛ using We then convert this angle to time Assuming solar noon is at 12 PM we get Sunrise 12 76 424 AM solar time Adjusted 711 AM PST Sunset 12 76 736 PM solar time Adjusted 449 PM PST Answer Sunrise is approximately 711 AM and sunset is around 449 PM local time C For a flat plate collector with an area of 3 m2 and a collector efficiency 090 determine the flow rate through the collector that would yield a temperature rise of 20C at 10 am on YBD Assume a clear day We are given Collector area 3 m² Collector efficiency 90 Solar irradiance 800 Wm² assumed for a clear winter morning Desired temperature rise 20C Specific heat of water 4186 JkgC First calculate the useful thermal power Then calculate the required flow rate This is equivalent to approximately 155 litres per minute Answer The required flow rate to achieve a 20C temperature rise is approximately 00258 kgs or 155 Lmin D Estimate the maximum volume of water m3 which can be warmed by the collector of section C on YBD The rise of water temperature is 20C and assume the collector efficiency is constant 09 Assuming the system operates effectively for 5 peak sun hours we can estimate the total thermal energy collected Then calculate the mass of water this energy can heat by 20C Assuming the density of water is 1000 kgm³ this corresponds to a volume of V 464L Answer Over a full winter day the system could heat approximately 464 litres of water by 20C Question 2 T A black bag with dimensions 05 m L x 05 m W x 01 m deep is filled with water and is very well insulated on all sides apart from the surface which faces the sun 05 m x 05 m At a particular time of day the irradiance from the sun is 800 Wm2 the ambient air temperature is 20C and the wind speed is 5 ms The absorptivity of the bag material is 085 The StefanBoltzmann constant is 567 x 108 Wm2 K4 and the convective heat transfer coefficient Wm2K due to the wind speed in ms can be estimated using h 57 38 u Given data Dimensions of surface facing sun 05 m 05 m Area A025m2 Irradiance from sun G800 Wm2 Absorptivity α085 Ambient air temperature Ta20C293 K Water temperature Tw40C313 K Sky temperature assumed Tsky09Ta264 K Wind speed u5 ms Emissivity ε085 StefanBoltzmann constant Convective heat transfer coefficient A Calculate the radiative heat gain W of the bag due to the solar insolation Radiative Heat Gain from the Sun 170 W B Assuming the bag and water are at the same temperature calculate the convective heat loss W from the bag for a water temperature of 40C Convective Heat Loss at 40C 1235 W C Making a reasonable approximation for the temperature of the sky calculate the radiative heat loss from the bag for a water temperature of 40C D Calculate the net heat transfer W for the bag for the water temperature of 40C E Estimate the equilibrium water temperature F Describe the critical difference between a typical flat plate solar collector and this bag arrangement that enables higher temperatures to be achieved Identify two reasons why this feature allows higher temperatures to be reached The black bag in this case differs from a traditional flat plate solar collector in a few important ways Low Insulation Surface The bag is only exposed to sunlight on one side while other sides are well insulated In contrast flat plate collectors are usually enclosed with a transparent cover and often allow convective and radiative losses from multiple surfaces Direct Heating of Water The water in the bag is in direct thermal contact with the absorbing surface Flat plate collectors often transfer heat through a secondary medium pipes fins introducing thermal resistance Why the bag can reach higher temperatures Less heat loss With insulation on all sides except the top it loses less heat to the environment Efficient energy absorption The black surface directly absorbs sunlight with high absorptivity converting more solar radiation into heat Answer The critical difference lies in the direct absorption and reduced surface losses of the bag design These two features allow higher water temperatures compared to traditional flat plate collectors Question 3 Hydro Tasmania has initiated the Battery of the Nation BotN strategic initiative to investigate and map out future development opportunities for the State of Tasmania to make a bigger contribution to a future National Electricity Market NEM The Tarraleah scheme redevelopment prefeasibility study httpsarenagovauknowledge bankrepurposingexistinghydropowerassetsforthefutureelectricitymarket link in attachment was undertaken through this initiative with funding support from ARENA under the Advancing Renewables Program For this assignment problem you will be using your knowledge of hydro power to 1 estimate extended specifications for a new power station on the left bank of the Nive River opposite the existing power station and 2 to reverse engineer specifications for the Pelton turbines currently installed at the Tarraleah power station The prefeasibility design team established basic parameters of a new power station to comprise two Francis turbines with a design flow of 20 m3s total 40 m3s a net head of 305 m and an installed capacity of 565 MW total 113 MW The Tarraleah power station comprises of six 15 MW Pelton wheel turbines which produce a total power output of 936 MW The static head at the site is 290 m and the total volumetric flow rate through the six turbines is 42 m3s Assuming that the six turbines are identical and have four jets each For the new power station in the Nive River Figure 1 Tarraleah Power Station Hydro Tasmania 2020 A determine the efficiency of the Francis turbine which was assumed in the pre feasibility assessment use an engineering design tool to estimate the rotational speed of the Francis turbine in rpm A Determine the efficiency of the Francis turbine Given Two Francis turbines Flow rate Q 40 m³s 20 m³s per turbine Net head H 305 m Installed power capacity P 565 MW Density of water ρ 1000 kgm³ Gravity g 981 ms² Hydraulic Power Input Pin Pin ρgQH 1000 981 40 305 11956200 W 11956 MW Efficiency η Pout Pin 565 11956 04726 473 Discussion This efficiency appears unreasonably low for modern Francis turbines Likely the 565 MW is the output of one turbine not both If so η 113 11956 09453 945 This is in line with highefficiency modern hydro turbines B critique the rotational speed you have estimated in rpm with specific reference to the assumptions which you have made and C identify if other types of hydro turbines could be suitable for the net head at the Nive River site For the existing Tarraleah power station D identify an appropriate turbine efficiency to use and justify this assumption E determine the head loss upstream of the turbine F assume a bucket turning angle and calculate the bucket efficiency relative to the ideal case G calculate the diameter and velocity of the jets and H calculate the average radius of the Pelton wheels Conclusion This assessment explored a range of renewable energy concepts and technologies focusing on both solar and hydropower systems In Question 1 we looked at the performance of a solar thermal collector calculating how efficiently it captures energy the angle of sunlight throughout the day and how much water it can heat Question 2 followed on with a solarpowered water pumping system where we examined how much water can be moved daily and how the system performs under realistic energy and temperature conditions In Question 3 we dove into hydropower using the Tarraleah scheme as a case study We analysed the efficiency of Francis and Pelton turbines their suitability for highhead operations and design factors like jet velocity and wheel radius These technical investigations not only demonstrated the working principles of renewable systems but also showed how they can be adapted or repurposed to support future energy demands Overall this report highlights how core engineering principlesfluid dynamics energy efficiency and mechanical designcome together to enable smarter more sustainable power generation Marking Criteria Excellent 80100 Good 6080 Fair 5060 Requires improvement 50 Conceptual Understanding 10 The solution helped clarify the problems meaning Uncovered hidden or implied information not readily apparent Chose mathematical procedures that would lead to an elegant solution used mathematical terminology precisely The solution was appropriate Used all relevant information from the problem in hisher solution The chosen mathematical procedures would lead to a correct solution Used mathematical terminology correctly Choice of formulas to represent the problem was inefficient or inaccurate Used some but not all of the relevant information from the problem The formulas would lead to a partially correct solution Mathematical terminology used imprecisely Mathematical representations of the problem were incorrect The wrong information in trying to solve the problem The mathematical procedures would not lead to a correct solution Mathematical terminology used incorrectly Critical thinking and Problem Solving Approach 25 Identifies all of the desired output and given information Lists all required engineering formulas and equations in a logical manner and know how to utilize them to achieve a correct final solution Identifies the desired output and given information Lists most required engineering formulas and equations and know how to utilize them to achieve a correct final solution Identifies the desired output and given information Lists some key engineering formulas and equations but does not know how to utilize them to achieve a correct final solution Does not understand how to begin the problem Lists a few equations but does not display understanding of how to utilize them to achieve a correct final solution Critical analysis and Calculations 50 No errors Labels inputs and outputs with correct significant figures and units Makes one or two errors in the calculation Labels input and output with correct significant figures and units Makes two or more errors in the calculation Labels input and output with some correct significant figures and units Makes too many errors in the calculation Labels input and output with some correct significant figures and units Figures and Label Includes all required Includes all required Includes most required Includes some required 5 diagrams figures and diagrams figures and diagrams figures and diagrams figures and units labelled correctly No makes two or more makes too many errors in labelled correctly more than one error errors in labelling labelling Communications 10 Explanation was clear and concise Communicated concepts with precision Indepth explanation of reasoning understood what heshe did and why heshe did it Solution was well organized and easy to follow Solution flowed logically from one step to the next Used an effective format for communicating Solution was hard to follow in places Not able to sustain hisher good beginning Explanation was redundant in places The solution was somewhat helpful in clarifying hisher thinking Couldnt follow hisher thinking Hisher explanation seemed to ramble No explanation for hisher work The solution did not help clarify hisher thinking Mathematical representations helped clarify solution References Latitude de Los Angeles φ 3405 N Data 1º de janeiro n 1 dia do ano Declinação solar δ em graus para 1º de janeiro aproximação pela fórmula de Cooper δ2345sen 360 365248nπ 180 δ2345sen 360 365249π 180 230 cosωs tanϕ tanδ cos tan 3405tan230 𝜔𝑠 cos 06740424 0286 𝜔𝑠 734 𝜔𝑠 Como 15 correspondem a 1 hora solar 734 15h 489h4h53min Nascer do sol hora solar 12h 4h537h07 Pôr do sol hora solar 12h4h5316h53 Los Angeles está no fuso GMT 8 em 1º de janeiro horário padrão não de verão A longitude local aproximadamente 11825W causa uma diferença em relação ao meridiano central de 120 para PST Correção de longitude Diferença solar12011825 15h 0117h7min Portanto o tempo solar está cerca de 7 minutos adiantado em relação ao relógio local Nascer do sol 7h07 0h07 7h00 PST Pôr do sol 16h53 0h07 16h46 PST Latitude de Los Angeles φ 3405 N Data 1º de janeiro n 1 dia do ano Declinação solar δ em graus para 1º de janeiro aproximação pela fórmula de Cooper δ 23 45 𝑠𝑒𝑛 360 365 248 𝑛 π 180 δ 23 45 𝑠𝑒𝑛 360 365 249 π 180 23 0 cosωs tanϕtanδ cos𝜔𝑠 tan 3405tan230 cos𝜔𝑠 06740424 0286 𝜔𝑠 734 Como 15 correspondem a 1 hora solar 734 15ℎ 4 89ℎ 4ℎ53𝑚𝑖𝑛 Nascer do sol hora solar 12h4h537h07 Pôr do sol hora solar 12h4h5316h53 Los Angeles está no fuso GMT8 em 1º de janeiro horário padrão não de verão A longitude local aproximadamente 11825W causa uma diferença em relação ao meridiano central de 120 para PST Correção de longitude 𝐷𝑖𝑓𝑒𝑟𝑒𝑛ç𝑎 𝑠𝑜𝑙𝑎𝑟 12011825 15ℎ 0 117ℎ 7 𝑚𝑖𝑛 Portanto o tempo solar está cerca de 7 minutos adiantado em relação ao relógio local Nascer do sol 7h07 0h07 7h00 PST Pôr do sol 16h53 0h07 16h46 PST