Warm-a-Matic Hot Cup Team Yamagochi International Michael Brupbacher, Tara Feller, Ian Levy, Craig Sobin, Alex Vanarelli
YAMAGOCHI INT L CORP YIC was incorporated in 1995 by Gordon Baba Miles YIC has developed concepts for solar powered hot beverage/food consumption and cooking containers. Warm-a-Matic Heating System Captures solar energy using photovoltaic technology. To be implemented on food and beverage containers. Maintain temperatures of beverages for an extended period of time. Heat food from ambient to a desired temperature i.e. slow cooking.
PROJECT SCOPE REFINEMENT Initial Project Goal Maintaining Constant Temperature Slow Cooking Capability Scope Refinement Maintaining Constant Temperature Target Performance Values Definition of Metrics
CONSTRAINTS Chemically inert Safe shape Safe electricity levels Safe separation of liquid and electric elements Housing and electric system unable to melt/deteriorate/ignite
WANTS Contain beverages and allow for consumption Maintain desired beverage temperatures Insulate for heat conservation Collect solar energy Convert and store solar energy Solar panel must be adhered to the cup Removable lid Size to fit in cup holder Ease of use Ability to slow cook Auxiliary power options
COFFEE HEAT LOSS Coffee sipped casually on a 72ºF afternoon The minimum temperature found to be 125ºF
METRICS Cost $10 per cup at mass production Maintained Temperature Range 135⁰ to 165⁰ Size Fit in 3 ½ diameter, 2 ½ depth cup holder Long Battery Life minimum: 1 hour. goal: 2 hours. Capacity minimum: 16 oz. goal: 24 oz. Weight 3.5 lbs. or less
MATERIALS Common structural materials used in travel mugs include: Glass Polymers Stainless steel Based on durability issues and the desire for a safe robust design, glass was eliminated from consideration. Polypropylene was chosen as a viable polymer option using the CES package, limiting the following factors: Price Young s modulus Melting point Thermal conductivity
SOLAR CELLS Miniature Encapsulated Solar Cells Applicable where use could cause damage to the solar cells. Current output range of 100-1000 ma. Low cost with a price range of $3-$10. Flexible Thin Film Solar Cells Can be adhered directly to the cups surface. Current outputs up to 200 ma. Prices range from $2-$40.
BATTERIES Nickel-Zinc: Higher voltage than competitors. Charging current needs to be within capacity of battery. Energy Density 280 Wh/L Lithium Ion: High energy to weight ratio. Loss in charge during non use. Energy Density 250-360 Wh/L Nickel-Metal Hydride: Requires control to avoid overcharging. Recommend a higher current to charge. Energy Density 140-300 Wh/L
HEATING ELEMENTS Thick Film Heaters Distribute heat evenly and consistently. Can be adhered directly to the applications surface for efficient heat transfer. Nichrome Heating Coils Low cost with prices ranging from $2-$10 dollars. Can be coiled to the specifications of the design.
INSULATION Pourable Foam Insulation Thermal conductivity ~.16 W/mK Expands to fill any container Also works as a high performance adhesive Low density rigid foam is ideal for thermal insulation Vacuum Insulation Effectively eliminates heat transfer Custom sizes available
OUTER CASING MATERIAL Outer Casing Material Multiplier Stainless Steel Polypropylene Low Thermal Conductivity 3 0 1 Ease of Fabriction 2 0 1 Durability 1 1 0 Low Cost 4 0 1 Totals 1 9
INNER LINER MATERIAL Inner Liner Material Multiplier Stainless Steel Polypropylene High Thermal Conductivity 5 1 0 Ease of Fabrication 2 0 1 Durability 1 1 0 Chemically Inert 5 1 1 Low Cost 3 0 1 Totals 11 10
SOLAR PANEL RANKING Solar Panels Multiplier Flexible Film Solar Cells Miniature Encapsulated Solar Cells Current Output 4 1 0 Durability 2 0 1 Lifetime 2 1 1 Least Occupying Volume 1 1 0 Solar Surface Area 3 1 0 Low Cost 3 0 1 Totals 10 7
BATTERY SYSTEMS Battery Systems Multiplier Nickel Metal Hydride Lithium Ion Nickel Zinc Lifetime 2 1 2 0 High Voltage 2 0 2 1 Max Current Output 4 2 1 0 Low Volume 2 0 2 0 Discharge Capacity 3 2 1 0 Low Charging Current 3 0 1 2 Ease of Charging 2 0 2 2 Low Cost 1 1 0 2 Totals 17 26 14
HEATING ELEMENTS Heating Elements Multiplier Thick Film Resistive Heater Nichrome Heating Coil Ease of Implementation 3 1 0 Power Rating 2 0 1 Heat Transfer Efficiency 4 1 0 Volume 1 1 0 Low Cost 4 0 1 Totals 8 6
INSULATION Insulation Multiplier Vacuum Polyurethane Foam Low Thermal Conductivity 2 1 0 Ease of Implementation 2 0 1 Low Cost 1 0 1 Totals 2 3
CONTROL Controls Multiplier Three Way Switch Potentiometer Temperature Sensor Controlled Ease of Implementation 3 2 1 0 Ease of Use 1 1 0 2 Low Cost 2 2 2 0 Totals 11 7 2
SUB-SYSTEMS Outer Casing Material Stainless Steel Polypropylene Inner Liner Material Stainless Steel Polypropylene Solar Panels Flexible Film Solar Cells Miniature Encapsulated Solar Cells Battery Systems Nickel Metal Hydride Lithium Ion Nickel Zinc Heating Elements Thick Film Resistive Heater Nichrome Heating Coil Insulation Vacuum Polyurethane Foam Controls Three Way Switch Potentiometer Temperature Sensor Controlled
HOW IT WORKS A. Flexible Thin Film Solar Panel B. Lithium Ion Polymer Battery C. SPDT Switch D. Thick Film Resistive Heater A C E. Stainless Steel Inner Liner F. Polyurethane Foam Insulation G. Polypropylene Outer Casing H. Snap Action Thermostat G D E H B
HEAT TRANSFER MODEL o To ho k Steel k polyurethane i Ti hi r1 r2 r3 q 3 layer composite wall radial conduction Natural convection on the inside of the inner liner and outside of the outer shell. k polypropylene r4
HEAT TRANSFER MODEL RESULTS As the thermal properties of water and air do not fluctuate significantly over the given temperature range, the heat transfer model predicts a rather linear relationship between heat loss and ambient temperature.
Heat Loss(W) OUTER CASING DIAMETER DETERMINATION 8 7 6 Shape Affect 5 4 3 2 1 0 3 3.5 4 4.5 5 5.5 6 Outer Diameter (in) Room Temperature Ambient The analysis of the affect of shape on heat loss led to the optimal outer diameter.
LIGHT INTENSITY TEST Light Source Opaque Surface Width α Camera Illuminated surface area images are captured with a digital camera. Images are converted to gray scale using MATLAB. β=90 PVC Tube
PV MODULE WIDTH DETERMINATION The light intensity test shows that the light intensity (blue profile) does not drop rapidly (red profile) with increasing distance from the center line.
PROTOTYPE COST Stereolithography Rapid Prototyping $987.00 Lithium Ion Batteries $32.00 Thick Film Flexible Heater $81.00 Flexible Solar Panels $45.00 Polyurethane Foam Insulation $31.00 Electronic Parts $41.00 Raw Materials $54.00 O-rings $23.00 Total Cost $1294.00
MASS PRODUCTION COST ESTIMATES Unit Cost Start-up Cost Flexible solar panel $6.00 $5000 Stainless Steel stamping $4.35 Lithium polymer batteries $3.50 Injection mold polypropylene $2.00 $5000 Blocking diode $1.10 Film resistive heater $1.00 Snap action thermostat $0.30 Three way switch $0.10 Polyurethane foam $0.10 Total $18.45 $10,000
TESTING Using multi-meters, the current and voltage output of the flexible thin film solar panel was tested to assess the panels battery charging capabilities. Through the use of a digital temperature sensor, temperature of the cups contents was monitored. The response time and functionality of the thermal-cutoff was assessed using a multi-meter and a digital thermometer.
Current (ma) SOLAR PANEL TEST 120 Solar Panel Output 100 80 60 Current output with dead cells (ma) Current output without dead cells (ma) 40 Ideal Current Output 20 0 0 10 20 30 40 50 60 70 Time (min)
Temperature (Deg F) HEAT LOSS FROM THE CUP 170 165 160 155 Heat Loss 150 No Heater 145 140 135 y = -0.4224x + 162.4 y = -0.3745x + 165.13 With Heater Battery Depletion Linear (No Heater) Linear (With Heater) 130 125 120 0 10 20 30 40 50 60 70 80 90 Time (min)
Cureent (A) SNAP-ACTION THERMOSTAT TESTING 1.6 1.4 Current vs. Time 1.2 1 T= 172 F 0.8 0.6 Snap Action Test 0.4 0.2 0 T = 138 F 0 5 10 15 20 25 Time (min) From the snap-action thermostat test it is clear that the current supplied to heating element is shut off for unsafe temperatures (>165) and reapplied when the fluid temperature is still within the metrics range (135-165).
FINAL CONCEPT VS. KEY METRICS Mass Production Cost $10 per cup Cost is $18.45. Maintained Temperature 135⁰F to 165⁰F Size Fit in 3 ½ diameter, 2 ½ depth cup holder Long Battery Life minimum: 1 hour. goal: 2 hours. Capacity minimum: 16 oz. goal: 24 oz. Temp Range Maintained for 80 minutes. The final design is dimensioned such that it will fit into a cup holder. Battery life is 35 minutes Capacity is 24 oz. Weight 3.5 lbs. or less Weight is 3 lbs
PATH FORWARD A method of significantly reducing heat loss to the surroundings is necessary to increase the functionality of this design. Although prototype cost considerations ruled out vacuum insulation, the cup design can be altered to accommodate for a change from polyurethane insulation to vacuum insulation. In order to charge the battery in a reasonable amount of time, a custom thin film solar cell would necessary. An alternative design comprising of two electronics housings that would be rotated in use and a roll-able solar panel will be recommended to the sponsor.
VACUUM INSULATION JUSTIFICATION Q Q Q Q Q With vacuum insulation in an ideal situation, the heat loss from a uniform temperature medium would essentially be reduced by 75%. Although cost prohibited the use of vacuum insulation for the prototype, the cup design could be easily modified to implement this technology in mass production.
SOLAR PANEL WIRING DIAGRAM i i Wiring A The power loss associated with the dead shaded cells can be regained with a custom flexible thin film solar panel design. To prevent loss from shaded cells due to environmental factors wiring B should be used. Wiring B
QUESTIONS?