Solar Stirling Engine Generator



Team #12471Solar Stirling Engine GeneratorProduct SpecificationsThomas GamerTara DoughertyDavid VolzerDaniel Thering02/21/2012Revision Level 02Solar Stirling Engine GeneratorProduct SpecificationTable of Contents1. Introduction and Feasibility Analysis2. Description and Overview of Planned Product3. Management Requirements4. Hardware and Software Requirements5. Testing CriterionSection 1 – Introduction and Feasibility Analysis1.1 Document OverviewThe purpose of the Product Specification Document (PSD) is to describe explicitly, completely, and without ambiguity the functionality and constraints of the Stirling engine generator. It also serves to provide details regarding concept and product development.1.2 Problem DefinitionThe need we are faced with is an effective way to transfer solar energy into electrical energy to output a specified amount of power. A lightweight portable device is required to harness solar energy, or heat from various sources, for the purpose of energy conversion and transfer.1.2 Justification for ProductThe goal is to create a device that can effectively transfer solar energy into electrical energy via a mechanical system that can withstand severe weather conditions, and operate independent of a user for a period of specified time. The output of the device would be compatible with common electronic devices for broad consumer use and application.Such a device would allow for electrical generation in remote regions with limited access to electricity as well as applications in space where photovoltaic cells become obsolete and inefficient due to effects of radiation.1.3 List and Description of SolutionsSolar CollectionThe following are possible solutions to effectively harness solar energy:Parabolic Dish – Method that utilizes a series of mirrors to form an approximate parabola. Collector focuses sunlight onto a thermal receiver which absorbs solar energy.Parabolic Trough – Method uses an array of parabolic troughs which have a linear system of pipes that absorb collected solar energy and transports it via a heat transfer fluid.Solar Central Receiver System – Method uses heliostats, or computer controlled mirrors, which reflect sunlight onto a centrally located thermal receiver. Typically a large array of heliostats in a circular layout surrounding the tower.Mechanical Device The following are possible solutions to effectively convert solar energy to mechanical power:Alpha Stirling Engine – Method that utilizes a heat source to create a temperature differential to operate a series of pistons according to the Stirling thermodynamic cycle. The alpha style uses a separate hot and cold cylinder and piston assembly to “pump” the expanding and contracting gas through the system to generate mechanical powerBeta Stirling Engine – Method that utilizes a heat source to create a temperature differential to operate a series of pistons according to the Stirling thermodynamic cycle. The beta style uses a single cylinder with two coaxial pistons. The displacer piston moves the gas to and from the hot and cold ends of the engine, and the sealed power piston produces the power stroke resulting from the expanding hot gas to generate mechanical power.Gamma Stirling Engine – Method that utilizes a heat source to create a temperature differential to operate a series of pistons according to the Stirling thermodynamic cycle. The gamma style operates similar to the beta style however the expanding hot gas escapes into a separate cylinder containing the power piston to generate mechanical power.Drive MechanismThe following are possible solutions to effectively translate the mechanical power to an electric generator:Rhombic Drive – Method translates vertical motion of the power piston to rotational motion via two spur gears and an output shaft.Bowtie Drive – Method translates vertical motion of the power piston to rotational motion via a triangular connection which simulate the motion of a four-bar mechanism.Symmetric Drive – Method translates vertical motion of power piston to rotational motion via two triangular connections which simulates the motion of a four-bar mechanism.Electric GeneratorThe following are possible solutions to effectively convert mechanical power to electrical power. Each is capable of producing the required power of 10W:Stepper Motor – Multiple (3+) “teeth like” poles that are offset from each other, output is in AC (3+ phases normally). Relatively low RPM will produce significant voltage levels.DC Motor – Smooth poles, number of poles not significant as it already contains the rectification circuit. Needs higher RPM to produce significant voltages.AC Motor – DC motor without a built in rectification circuit, produces AC current typically at high voltages and power levels. Magnet/Flywheel – AC motor built into flywheel.1.4 Feasibility Analysis of SolutionsNot all the aforementioned solutions are practical for the implementation of the product to achieve the intended goal. Therefore feasibility has been decided by the following factors:DurabilityPortabilityWeightCost effectivenessSystem complexityPower generation efficiency1.5 Recommended SolutionSolar CollectionParabolic Dish – This collection method has the advantages of high solar collection efficiency and portability.Mechanical Device Beta Stirling Engine – This engine design has the advantages of less weight due to the single cylinder, durability of the power piston seal, and power generation efficiency.Drive MechanismBowtie Drive – This mechanism design has the advantages of lower component weights and a decrease in system complexity.Electric GeneratorDC Motor – This motor has the advantages of no requirement for a rectification circuit or transformer which reduces total product weight and reduces system complexity.Section 2 – Description and Overview of Planned Product2.1 – Product Description2.1.1 – Product FeaturesSpring pin design for tool-free collapsibility and compact designAdjustable parabolic dish for optimal solar energy collectionSingle cylinder beta engine for compact and space efficient designFin array structure and regenerator on outside of cylinder for maximum thermal efficiencyUSB connector for broad consumer use and compatibility with common electronic devicesMolded resin base for durability and light weight design2.1.2 – Functions to be ProvidedSolar energy collectionFocusing of solar energy to generate heatConversion of thermal energy to mechanical power via Stirling engine technologyConversion of mechanical power to electrical power via electric generatorPower storage via Lithium-Ion batteries10+ Watts of power in the form of USB connector2.1.3 – Product Design Constraints20 lb. Maximum product weight limit (does not include solar collector)$500 Budget10 Watt at 5 Volts power generation requiredDurability to continuously operate user free for 1 yearDurability to withstand weather in Rochester, NYSection 3 – Management Requirements3.1 – Standard PracticesWeekly MeetingsTuesday: Team will meet Tuesday 11-2 pm for a general work day. Attendance in person is mandatory.Tuesday: Team will meet Tuesday evening at 8 pm via Skype for purpose of updates and communication. Team information will be disseminated. Mandatory online presence.Thursday: Team will meet Thursday afternoons 11-2 pm for a general work day. Attendance in person is mandatory.Friday: Team will meet Friday during the morning/afternoon for group discussion, advisory from guide, and product development. Attendance in person is mandatory.Project Scope ChangesAnything resulting in changes to the project scope must be formally agreed upon by team consensus and documented using the project change order form. This form is to be brought to the attention of the faculty guide and project sponsor. Barring their disapproval, the project changes can be implemented.Budget ChangesAnything resulting in changes to the project budget must be formally agreed upon by team consensus and documented using the budget change request form. This form is to be brought to the attention of the faculty guide and project sponsor. Upon receipt of written approval from the project sponsor and faculty guide, the budget changes can be implemented.Document ControlAll documents posted to edge must have the following items listed in their header or footer: current revision level, author, date of posting, and team number.3.2 – DeliverablesDeliverables Created During ProjectProject ManagementTeam Role AssignmentsCode of EthicsProject SummaryRisk AssessmentWork Breakdown Structure (WBS)RACI Matrix (Resource Responsibility Matrix)Project Timeline (Gantt Chart)Project Budget-EstimatedBudget Tracking SheetBudget Change Request FormScope Change Request FormDesignFunctional DecompositionStructural DecompositionPugh AnalysisSelected ConceptSimulation ResultsSimulation CodeSolid ModelsBill of MaterialsFeasibility AnalysisFabrication DrawingsCircuit DrawingsBuildPrototypeFinal ArtifactTestingTesting PlanEquipment Resource ListTest ResultsSuggested ImprovementsFinal DeliverablesFinal ArtifactWrite up Including:AbstractIntroductionTheorySimulation ResultsTesting ProcedureTesting ResultsDiscussion of key pointsConclusionSuggested ImprovementsAppendicesFabrication DrawingsCircuit DrawingsBill of MaterialsSimulation CodeSection 4 – Hardware and Software Requirements4.1 – Hardware Requirements4.1.1 – Equipment and ToolsMany parts will require the use of high precision tool room equipment as well as CNC machines to create the quality parts required. Quality measuring equipment will then be needed to ensure the parts are made correctly. All this work will be performed at D.P. Tool & Machine, and all other small less precise parts will be fabricated at RIT.4.1.2 – MaterialRaw materials, copper, aluminum, and steel will be used to create the Stirling engine base and engine components. Various coated steel and bronze parts will be purchased for linkage connections.4.1.3 – Ordered PartsMost parts and materials will be purchased from the following companies:McMaster-CarrDigiKeyField’s Hobby CenterMSR4.2 – Software RequirementsAll 3-D solid modeling and detail drawings will be created using the ProEngineer modeling package. Thermal analysis will be executed using ANSYS. USB dataloggers and thermocouples will be used during testing for data collection and processing.Section 5 – Testing5.0 – Testing CriterionEng. Spec. #DescriptionNominalPass/FailUnitS1Output Power≥ 10N/AWS2Output Voltage5+/- 0.2VS3System Weight< 20N/AlbsS41 year Maintenance FreeS4.1Able to Withstand Rain Exposure10N/AminS4.2Able to Withstand Wind Exposure10N/AminS4.3Able to Withstand Freezing> 4N/AhrS4.4Able to Withstand Heat Exposure> 4N/AhrS4.5Able to Withstand Continuous Use24hrS5System Self StartingN/A ................
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