ERAU RET 2012: SolaR STIRLING ENGINE

1. ERAU RET 2012 MORGAN Amber Morgan Marc Johnson Dr. Yan Tang Dr. Marc Compere ERAU RET 2012: SolaR STIRLING ENGINE

2. Invented 1816 by Robert Stirling • External combustion engine • Stirling cycle: • Isothermal Expansion • Isochoric Cooling • Isothermal Compression • Isochoric Heating ERAU RET 2012 MORGAN What’s A STIRLING ENGINE?

3. ERAU RET 2012 MORGAN PROS CONS • High efficiency (same as Carnot efficiency!) • Quiet • Can use variety of sources for heat input • Requires “warm-up” time • Large ∆T  stress • Solar – no joy if cloudy! STIRLING ENGINES

4. ERAU RET 2012 MORGAN How’s IT WORK? Power Piston Displacer Piston Stirling engine inside view – Beta Configuration Diagrams from Stirling, Engines, Andy Ross, 1982.

5. ERAU RET 2012 MORGAN TESTING THE SOLAR STIRLING • Using parabolic mirror to focus light • Stirling engine loaned from ERAU physics department

6. ERAU RET 2012 MORGAN TESTING THE SOLAR STIRLING • Using 20” diameter Fresnel lens to focus light • Coupled to small DC motor being run as generator • Measuring voltage across motor terminals

7. ERAU RET 2012 MORGAN TESTING STIRLING ENGINE • Too overcast to test with solar input  use propane torch to heat Stirling input cylinder • Measuring RPM, voltage, and temperature near top of shaft

8. ERAU RET 2012 MORGAN FlyWHEeL Rotation and Motor Voltage A graph of motor output voltage vs. angular frequency shows a direct relationship between the two with a slope of 0.078 V s.

9. Need heat input source focused at tip • Fresnel lens as light-gathering device was effective but required much adjustment; Parabolic dish was easier to “plug-n-play” • Diffuse sunlight (due to even thin clouds) is ineffective as energy source • Large ∆T needed for greater efficiency ERAU RET 2012 MORGAN WHAT WE LEARNED

10. ERAU RET 2012 MORGAN Power OUTPUT? • Maximum electrical power out: • P = V2/R • P = (1.1 V)2/(0.8 Ω) • P = 1.5 W Mechanical power out from rotation of flywheel… P = τω But τ’s not easy to measure as you might think! • How about an estimate for power from cycle area in ideal p-V diagram? • W = ∫p dV • For Stirling cycle, W= • mR(TH – TC) ln (V2/V1) • (7x10-6 )(320)(200)ln(1.2) • =0.09 J per cycle • P = W/t = 0.09 J*16rev/s =1.4 W

11. ERAU RET 2012 MORGAN TEACHING MODULES • Optics Motivation: Measuring light intensity important for determining efficiency. Focusing light to increase intensity required to use solar radiation as heat source for Stirling engine. • Thermodynamics Motivation: Heat transfer processes (conduction, convection, radiation) all evident in solar Stirling engine. Theoretical engine efficiency can be determined from first and second laws of thermodynamics.

12. ERAU RET 2012 MORGAN OPTICS MODULE • Student Objectives: After completing these activities, student should be able to • Describe how light given off by a source or incident upon a surface is measured • Explain what a point source is and describe the relationship between intensity and distance • Describe the relationship between irradiance and photocurrent of a photocell • Determine the index of refraction of a material by various methods • Draw ray diagrams for single mirror or lens systems (spherical mirrors and thin lenses) • Describe characteristics of images formed by single mirror or lens system depending upon object position • Define spherical aberration and show that a parabolic mirror has no spherical aberration • Explain that, despite the simplified rays used for thin lenses, all refraction occurs at the surfaces of a lens and explain what the benefit of using a Fresnel lab might be • Determine the maximum magnification of a single lens Marc Johnson with large Fresnel lens

13. ERAU RET 2012 MORGAN OPTICS MODULE Reflection and Refraction of Light • Snell’s Law Lab and Teacher Notes Page • Spherical Mirrors and Thin Lenses • Geometric Optic Notes (Teacher and Student) • Ray diagrams Rules, Characteristics Notes (Teacher and Student), and Practice Diagram Worksheet • Mirror and Lens Lab and Teacher Notes Page • “Telescope” lab • Parabolic Mirror - Solar cooker lab (with parabolic geometry) • Fresnel lens - “credit-card”-sized magnifiers lab and Teacher Notes Page Light Energy • Measuring Light Notes (includes refraction notes) (Teacher and Student) • Intensity and Distance Lab (Inverse Square Law) and Teacher Notes Page • Photovoltaic Cell Lab and Teacher Notes Page

14. ERAU RET 2012 MORGAN THERMODYNAMICS MODULE Objectives: Students will be able to • State and apply first and second law of thermodynamics • Explain microscopic origin of temperature (kinetic molecular theory) • Describe various methods of temperature measurement/determination • Define heat capacity and specific heat capacity • Describe heat transfer processes (conduction, convection, radiation) • Interpret, analyze and draw pressure vs. volume diagrams for various processes (isobaric, isochoric, isothermal, adiabatic) • Describe heat engine basic principle • Calculate heat engine efficiencies • Describe Carnot cycle and calculate Carnot efficiency • Distinguish between internal and external combustion engines • Describe Stirling cycle and calculate ideal Stirling efficiency

15. ERAU RET 2012 MORGAN Thermodynamics Module Thermal energy and temperature • Temperature Notes (Teacher and Student) • Thermal Energy Notes (Teacher and Student) • Specific Heats Lab • Thermometer Activity • Thermocouple Activity • Thermal Absorption Lab • Heat Conduction Lab Thermodynamic Processes, Cycles, and Heat Engines • Thermodynamics Notes (teacher and student) • Gas Laws Lab • Stirling Engine Background • Building Model Stirling Engine Lab • Solar Stirling Engine Demonstration (Teacher Notes and Videos)

16. ERAU RET 2012 MORGAN Thank YOU! • Thank you especially to Dr. Yan Tang, Dr. Marc Compere, Bill Russo and Mike Potash for many helpful suggestions, finding and making equipment, and taking the time to answer our questions!!!