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Introduction. Team Members Jeffrey Kung Richard Sabatini Steven Ngo Colton Filthaut. Faculty Advisor Jim Mohrfeld. Industry Advisor Christopher Keller. Underclassmen Walter Campos Alan Garza. Agenda. Goals Prototype Model Component/Material Selection Design Mechanical Design
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Introduction Team Members • Jeffrey Kung • Richard Sabatini • Steven Ngo • Colton Filthaut Faculty Advisor • Jim Mohrfeld Industry Advisor • Christopher Keller Underclassmen • Walter Campos • Alan Garza
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Goals • To have a working Stirling Engine that will serve as a portable generator capable of producing 2.5 kWh • To be able to run multiple common household appliances simultaneously
Household Appliances • Appliances (average): • Refrigerator/Freezer = Start up 1500 Watts • Operating = 500-800 Watts • Toaster Oven = 1200 Watts • Space Heater = 1500 Watts • Lights: Most common are 60 Watt light bulbs • Tools (average): • ½” Drill = 750 Watts • 1” Drill = 1000 Watts • Electric Chain Saw 11”-16” = 1100-1600 Watts • 7-1/4” Circular Saw = 900 Watts
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Cylinder Material Selection http://www.onlinemetals.com/ http://www.onlinemetals.com/ http://www.onlinemetals.com/
Piston Materials • Displacer Piston • Forged Steel • High in Strength • Retains Heat • Density of 0.279 lb/cu. in. • Power Piston • Forged Aluminum • Light Weight • High in Strength • Density of 0.101 lb/cu. in. http://www.mahle.com/ Ocyaniqueprofessionals.com
Alternator Selection http://www.mechman.com/ http://www.ecoair.com/ https://www.dcpowerinc.com/
Alternator Selection Calculation (Mechman) • Selecting an alternator is a key component when designing the Stirling engine to reach an output of 2.5kW • Rpms required from engine when using a 3:1 pulley ratio • 900 rpms needed from the engine • 2700 rpms needed from the alternator • 1 hp per 600 watts to run the alternator • To calculate the torque required to spin the shaft http://www.mechman.com/images/products-s-curve-big.png
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Mechanical Analysis Power and Displacer Piston Crank-Slider mechanism • Variables • Connecting Rod Length (L) • Crankshaft Arm Length (R) • Force on Piston (F) • Mass of Piston (M) • Angular Velocity (ω) • 900 rpm required => (ω)= 94.25 rad/s • ω R L M F
Mechanical Analysis 1.625:1 Displacerto Power dia. Ratio • Displacer Piston • Diameter: 6.5” (Piston) • Connecting Rod Length (L): 8.934” • Crankshaft Arm Length (R): 2.625” • Mass of Piston (M): 10 lbm • Power Piston • Diameter: 4” (Piston) • Connecting Rod Length (L): 5.956” • Crankshaft Arm Length (R): 1.75” • Mass of Piston (M): 1.561 lbm Regenerator Flywheel
Mechanical Analysis Piston Acceleration and Force • Power Piston Acceleration • Displacer Piston Acceleration • Power Piston Force • Displacer Piston Force
Mechanical Analysis Required Force
Mechanical Analysis Work/ Kinetic Energy(N*M) • KEY POINTS • Work being delivered to the system from 0 to 180 degrees (downward direction) • Starting pressure when Θ=0: 221 psi • Displacer piston dia: 6.5” • Power Piston dia: 4” • 20% Mechanical Friction loss • RPM=900 http://cnx.org/content/m32969/latest/
Mechanical Analysis Force Delivered to Force Required Check and Balance
Mechanical Analysis Torque ; ; -1
Mechanical Analysis Torque Related to Kinetic Energy C D A A E B Preferred Method WORK delivered from PRESSURE= 208.333 N*M WORK remaining after FRICTION= 166.664 N*M STORE HALF of the energy to be delivered for UPWARD movement of POWER PISTON (ϴ=180 to 360)
Mechanical Analysis Flywheel is typically set between .01 to .05 for precision
Mechanical Analysis Overview Pressure= 1.5 MPA (220 PSI) P 20% Energy Loss= 21.7 N*M K.E.=166.7 N*M Storing Half K.E. @ 0º to 180º) Deliver K.E. @180 ºto 360º= 83.36 N*M Constant Torque= 26.5 N*M http://enginemechanics.tpub.com/14037/css/14037_90.htm
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
First Order Design Method Total Volume=MAX(Vexp+Vcomp+Vdead) Total Volume= (7065.3 cm^3) • Average Pressure • =2.02 MPa Total Net Work(Joules) W=dθ W=232.2(Joules) Power Output(Watts) PNet Work *Frequency Power= 232.2(J)*(9.6)Hz Output Power= 2229(watts)
Second Order Design Method • It was not possible to run a second order analysis by simple calculations & equations because of the enormous amount of unknown variables so we built a program in MATLAB capable of running arrays & guess values to arrive at possible values • Our process for the Second Order Design Method. • Build Calculation Sheet On Excel capable of giving us accurate basic parameters • Designed MATLAB program capable of calculating numerous amount of engine variables at different speeds & pressures • Re-Designed Excel sheet to incorporate data from MATLAB program
Second Order Results Output values from Stirling Program imported into Excel We have picked 15 Hz (900RPM) because we can achieve a high enough torque to up-gear our engine ratio 3:1 giving us 2700(RPM) at a high output power of 3010 (watts) Freq. (Hz.)Power (Watts) Therm. Eff.%Torque (N.m)Pressure (Pascals)
Second Order Results Wout= net work done by entire engine Pe*dVe= The change in expansion volume as a function of expansion space pressure Pc*dVc=The change in compression volume as a function of compression space pressure Work in expansion space= 7162.2(Joules) Work in compression space= -6961.4(Joules) Pout= (7162.2)(J)+(-6961.4)(J) *(15Hz)=3010 Watts
FEA ANALYSIS Allowable Yield Stress for ChromMollyAISI 4140 at 600C is 60,40psi or (417MPa) Max Operating pressure is 376 psi Max Hoop Stress Equals= 14,368 psi
Second Order Design • Regenerator Design- • The regenerator reduces the heat transferred from expansion cylinder to compression cylinder by incorporating several small tubes & cylinder housing containing a porous mesh material which catches heat • The tubes help dissipate heat by maximizing surface area to help enable the convection of heat. • The tubes also help control the pressure & gas flow by causing a pressure drop which increases the gas velocity
Second Order Design • As the swept Volume increases by a factor of “x” the # of tubes must also increase by that factor(if you double the volume you double the tubes)
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
WBS 100% 100% 100% 61%-99% 100% 31%-60% 100% 1%-30%
Gantt Chart (Year)
Agenda • Goals • Prototype Model • Component/Material Selection • Design • Mechanical Design • Thermodynamic Design • Cost Analysis • WBS/Gantt Chart • Risk Matrix
Risk Matrix
Questions? Cot-mect4276.tech.uh.edu/~stngo3