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Heat Transfer Design Project

Remove "Watch out for Ice on Bridge" Designs
by

Jessica Hunnicutt

on 29 April 2010

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Transcript of Heat Transfer Design Project

ME - 321 Heat Transfer
Design Project By:
Zack George
Jessica Hunnicutt
Brandon Schumm Objective Remove the 'Watch For Ice On Bridge' Sign Brainstorm and Generate Conceptual Designs Must be:
Cost effective
Creative
Feasible
Safe
Simple Ideas Insulation
Add insulation material to sides
and bottom of bridge
Prevent heat loss
Build a grated bridge
Water runs right through the bridge surface
No surface area for ice formation Geothermal
Use earth's underground heat
Run piping inside bridge deck
Electric Coils
Coils imbended in the concrete
Run with solar power
Run through electric company Heated Tarp
Roll out during winter months
Thin piping or thin electrical wire
One big electric blanket Assumptions Treating Bridge as Concrete Slab Average Dimensions
Deck Depth: 10" (0.25 m)
Width: 30' (9.144 m)
Length: 98.4' (30 m) Surface Temperature of Bridge maintained
at a minimum of 1 degree Celsius Temperature of Air is aproximately -2 degrees Celsius Thermal Resistance is low! One Dimensional Heat Transfer (for simplicity) Geothermal Heating Several Varations Used for Houses and Buildings Run piping into the ground
Use a pump to recirculate water
Use pipes to distribute the earth heated water in the concrete deck
Heat from pipes will be transfered through the concrete slab to heat the surface Before Bridge is Built http://www.findsolar.com/index.php?page=rightforme
Powered By:
Solar Energy
Electric Company Calculations (Eliminate ice formation on bridge) Energy Needed Wind Blowing Across the Bridge Wind Blowing Along the Bridge Wind Speed of 11.13 mph (5.48 m/s) No Wind under the bridge (free convection due to beams blocking the wind) Neglecting heat conducted through beams on bottom of bridge Entirely Turbulent Flow Along the Bridge Flow begins laminar when blows across the bridge Pros:
Environmentally Friendly
Low Annual Cost
Little or No Maintance
"Kiss"
Safe and Reliable
Cons:
Large Intial Cost
Only for New Bridges
Structurally Questionable
Contamination
Improvements
Combine Geothermal and Insulation
Final Design If This Doesn't Work.... There is always the old fashion way of removing a sign.... Just Kidding! The End! ... Any Questions? Closed Loop (change in pressure comes from major head loss only)
Neglect minor losses
Temperature of water entering the bridge is 11°C and leaves at 1°C
Pipes are spaced at one foot increments
Heat loss by the bridge is supplied by the water (operating at steady state)
Water pipe diameter of ¾”
Drawn tubing
h = hf at T
Thermal Calculation Assumptions Initial setup cost:
Raw material: $9,500
Annual cost: $80
Labor & Maintence: (Not determined
at this time)

Variations:
Use solar power for pump electricity
Electric heating coils in replace
geothermal pipes
Costs Geothermal Modeling
Full transcript