2. Introduction Faculty Advisor Jim Mohrfeld Richard Sabatini Steven Ngo
Team Members
Jeffrey Kung
Richard Sabatini
Steven Ngo
Colton Filthaut
Faculty Advisor
Jim Mohrfeld
Richard Sabatini
Steven Ngo
Colton Filthaut
Underclassmen
Walter Campos
Alan Garza
Richard Sabatini
Steven Ngo
Colton Filthaut

3. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

4. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

5. 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

6. Household Appliances Appliances (average):
Refrigerator/Freezer = Start up 1500 Watts
Operating = 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” = Watts
7-1/4” Circular Saw = 900 Watts

7. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

8. Stirling Engine Prototype Model

9. Animation of Stirling Engine

10. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

11. Heat Source Fuel Density Practicality Price Max Temperature
Propane Gas
2.01 g/cm³
$2.48 per gallon
1800˚ C 5 4 3
Electric Burner
(1.4 kW) ~
16¢ per kWh
800˚ C 1 2
Gasoline
.75 g/cm³
$3.504 per gallon
1000˚ C

12. Working Gas Working Fluid Thermal Conductivity Absolute Viscosity
Specific
Heat
Gas
Constant
Safety/ Practicality
Nitrogen
.026 W/mC
0.018 centipoises
1040 J/kgK
297 J/kgK 1 3
Helium
.149 W/mC
0.02 centipoises
5188 J/kgK
2077 J/kgK 4
Hydrogen
0.182 W/mC
0.009 centipoises
14310 J/kgK
4126 J/kgK 5

13. Hot Cylinder Material Selection
Thermal Conductivity
Yield Strength
Price
Melting Temperature
316 Stainless Steel
14 W/(m.K)
60,200 psi
$74.00/ft
1400˚ C 5 4 2
304 Stainless Steel
16 W/(m.K)
31,200 psi
$57.00/ft
1450˚ C 1
4130 Chromoly Steel
43 W/(m.K)
63,100 psi
$70.00/ft
1430˚ C 3

14. Cold Cylinder Material Selection
Thermal Conductivity
Yield Strength
Price
Melting Temperature
6061 Aluminum
205 W/(m.K)
40,000 psi
$25.00/ft
580˚ C 4 5 2
C101 Copper
401 W/(m.K)
36,530 psi
$556.00/ft
1083˚ C 3 1
304 Stainless Steel
16 W/(m.K)
31,200 psi
$57.00/ft
1450˚ C

15. Piston Materials Displacer Piston Power Piston Forged Steel
High in Strength
Retains Heat
Density of lb/cu. in.
Power Piston
Forged Aluminum
Light Weight
Density of lb/cu. in.
Ocyaniqueprofessionals.com

16. Alternator Selection Brand Voltage Amps Torque Req. Price Total
Mechman
14 Volts
240A
8.092 lb-ft
$350.00 4 3 15
Eco-Tech
325A
9.000 lb-ft $ 5 1 10
DC Power
250A
lb-ft
$590.00 2 13

17. Alternator Selection Calculation (Mechman)
Selecting an alternator is a key component when designing the stirling engine to reach an output of 2.5kW
𝐴𝑚𝑝𝑠= 𝑤𝑎𝑡𝑡𝑠 𝑣𝑜𝑙𝑡𝑠 = 2500𝑤 14𝑣 =178.5 𝐴𝑚𝑝𝑠
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
2500𝑤 600𝑤 =4.16ℎ𝑝
To calculate the torque required to spin the shaft
𝑇= ℎ𝑝∗3300 2𝜋∗𝑟𝑝𝑚𝑠 = 4.16ℎ𝑝∗3300 2𝜋∗2700𝑟𝑝𝑚𝑠 =8.092 𝑓𝑡∗𝑙𝑏𝑠

18. Cooling Fins
Cooling fins increases efficiency which increases compression energy to run
Materials considered are Aluminum or Copper

19. Cooling Fins Calculations

20. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

21. Calculation Process Base Engine Requirements (RPM, Power)
Engine Calculations
(Heat, Dimensions, Pressure, Work)
Heat Transfer & Regenerator Calculations
Efficiency &Total Work Loss Calculations

22. Mechanical Analysis F ω R L M Power and Displacer Piston Variables
Connecting Rod Length (L)
Crankshaft Arm Length (R)
Force on Piston (F)
Mass of Piston (M)
Angular Velocity (ω)
900 rpm required => (ω)= rad/s
Crank-Slider mechanism F L R ω M

23. Mechanical Analysis
First iteration 1:1.5 Piston to Displacer dia. Ratio
Power Piston
Diameter: 4.5”
Connecting Rod Length (L): 5.956”
Crankshaft Arm Length (R): 1.75”
Mass of Piston (M): lbm
Displacer Piston
Diameter: 6” (Box Piston)
Connecting Rod Length (L): 8.934”
Crankshaft Arm Length (R): 2.625”
Mass of Piston (M): 10 lbm

24. Piston Acceleration and Force
Mechanical Analysis
Piston Acceleration and Force
Power Piston Acceleration
Displacer Piston Acceleration
Power Piston Force
Displacer Piston Acceleration

25. Mechanical Analysis
Required Force
Displacer Piston
Power Piston

26. Mechanical Analysis Work (N*M) Displacer piston Power Piston
Power Piston

27. Mechanical Analysis Force Delivered to Force Required
Check and Balance

28. Mechanical Analysis
Torque -1 ; ;

29. Mechanical Analysis
Torque Related to Kinetic Energy A D E C B

30. Mechanical Analysis Flywheel
is typically set between .01 to .05 for precision

31. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

32. Our Current Design Progress
First Order Design Method
Calculate Ideal Adiabatic & Isothermal Conditions.
Analyze changes in temperature, pressure & volume in order to get an estimated power output
Calculate initial engine parameters ( Swept Volumes, Dead volumes, Change in mass, Stroke Lengths, & rotational speed)
Create a finished first order Design Calculation Sheet allowing us to obtain the previous variables.
Second Order Design Method
Calculate real life conditions & losses (gas pumping/friction losses, heat transfer rate, porosity, mass flow rate of gas, vibrational forces, principle stress, fatigue rate)
Design & Calculate regenerator parameters, tubing dimensions, & Fin parameters.
Design & Build a calculation sheet allowing us to obtain several arrays of values for each variable in order to find the best engine operating conditions

33. First Order Design Method
Average Pressure
𝑃𝑎𝑣𝑔= 𝑀∗𝑅 𝑉𝑐 𝑇𝑘 + 𝑉𝑘 𝑇𝑘 + 𝑉ℎ 𝑇ℎ + 𝑉𝑒 𝑇ℎ
𝑃𝑎𝑣𝑔 =2,029 Pa
Total Volume=MAX(Vexp+Vcomp+Vdead)
Total Volume= ( cm^3)
Total Net Work(Joules)
W= 𝑃∗ 𝑑(𝑉𝑡𝑜𝑡𝑎𝑙) 𝑑𝜃 dθ
W=232.2(Joules)
Power Output(Watts)
Power=Net Work *Frequency
Power= 232.2(J)*(9.6)Hz
Output Power= 2229(watts)

34. 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

35. Second Order Design Method
Stirling Master MATLAB/FORTAN Program Skeletal Structure
Put in the initial variables calculated from second order excel sheet
The program links the input
Functions to the script program
which calculates unknown variables

36. Second Order Design Method
Output calculated variables
From the different conditions with respect to speed we can see the optimal conditions we will want

37. Second Order Design Method
Stirling Master MATLAB/FORTAN Program Skeletal Structure
The script that defines the input functions for the program
The beginning of the 1st part of the script which helps us find values hard to obtain like that mass of the gas at every angle position
Ex. From the ideal
Gas law PV=MRT
You want to find your mass
but can not because you also don’t know your change in temperature, the program will run a series of variable arrays that will coincide with your desired output power and pressure

38. Second Order Results
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)
Output values from Stirling
Program imported into
Excel
Freq Power Therm. Eff. Torque Pressure

39. 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= (Joules)
Work in compression space= (Joules)
Pout= (7162.2)(J)+( )(J) *(15Hz)=3010 Watts

40. Second Order Results

41. 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
The mesh material not only reduces the heat flow to the compression cylinder but also helps throw heat back into the hot cylinder as the gas flows back.

42. 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)

43. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

44. Cost Analysis Part Quantity Price Estimated Total $4,089.00 Mechanical
Cylinders 2
$200.00
Regenerator 1
$450.00
Crankshaft
$400.00
Miscellaneous X
$300.00
Raw Material
Seals
Gaskets
$250.00
Piston
Bearings
$150.00
Cooling Fins
Frame
$120.00
Pulley
$40.00
Coupling
$30.00
Belt (Rubber)
$20.00
Pressure Gauge
$50.00
Temperature Gauge
Tachometer Gauge
$25.00
Heat Source
Propane Cylinder
Propane Torch
Propane Regulator
Electrical
Alternator
$349.00
Inverter
$350.00
Battery 12v
Voltage Regulator
Outlets
$10.00
Wiring
$1/ft
Estimated Total
$4,089.00

45. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

46. WBS 100% 100% 100% 61%-99% 100% 31%-60% 100% 1%-30% Stirling Generator
Research
Concept & Feasibility
Market Research
Cost Analysis
Project Development
Component Selection
Intro Design
Design
Detailed Design & Calculation
CAD/CAM Design Components
Analysis & Data Results
FEA Thermal Analysis
FEA Mechanical Analysis
WBS
100%
100%
100%
61%-99%
100%
31%-60%
100%
1%-30%

47. Gantt Chart

48. Agenda Goals Prototype Model Component/Material Selection Design
Mechanical Design
Thermodynamic Design
Cost Analysis
WBS/Gantt Chart
Risk Matrix

49. Risk Matrix 1 2 3 4 5 6 7 8 9 10 SEVERITY RISKS MITIGATION
INSUFFICIENT FUNDING
CONTINUE TO PURSUE FUNDING AND/OR ALTERNATE POSSIBILITIES 2
STIRLING ENGINE DOESN'T RUN
DESIGN ENGINE FOR EASY PART ASSEMBLY AND MODIFICATION 3
LACK OF INDUSTRY ADVISOR
WHERE THE INDUSTRY ADVISOR WOULD HAVE HELPED, TEAM MEMBERS WILL BE FORCED TO TAKE MORE TIME OUT TO RESEACH AND UNDERSTAND THE MATERIAL 4
LATE FABRICATION OF PARTS
COORDINATE WITH MANUFACTURES/ ORDER PARTS EARLY/ UNDERSTAND HOW TO MACHINE THE PART BEFOREHAND 5
POOR DESIGN ASSEMBLY OF COMPONENTS
STAY ON TASK AND COORDINATE WITH TEAM MEMBERS ON EVERY STEP 6
INJURY IN MACHINE SHOP
FOLLOW ALL SAFETY RULES 7
APATHETIC TEAM MEMBER
TALK TO THE TEAMMATE AND SOLVE THE ISSUE QUICKLY 8
TEAM HEALTH
GET ENOUGH REST AND NOT WORK TOO LATE 9
TEAM TIME & AVAILABILITY
SET DAYS WHEN TO WORK AND COORDINATE CLASS/JOB SCHEDULES 10
PART DAMAGE
SEND BACK PART AND WORK ON DIFFERENT SECTION

51. Questions?
Cot-mect4276.tech.uh.edu/~stngo3