ENGINEERING WORLD HEALTH: COLD BOX Josh Arenth Cynthia Bien Graham Gipson Elise Springer Brittany Wall Group 19 Engineering World Health: Cold Box (Group.

ENGINEERING WORLD ENGINEERING WORLD HEALTH:HEALTH:

COLD BOXCOLD BOXJosh ArenthCynthia Bien

Graham GipsonElise Springer

Brittany WallGroup 19

Engineering World Health: Cold Box (Group 19)

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EENGINEERING NGINEERING WWORLD ORLD HHEALTHEALTH

Organization background:

Founded in 2001 by Dr Robert Malkin at Duke Univ.

Charitable organization that collaborate with collegiate engineering programs

Improves conditions of hospitals in developing nations

Multi-step process:

(1) Assessment of hospitals(2) Ship container of refurbished medical

equipment(3) Install equipment and train at location(4) Return to location to reinforce training

Engineering World Health: Cold Box (Group 19)

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WHYWHY WORK FOR EWH? WORK FOR EWH? Want to improve healthcare in developing countries

Impact the quality of healthcare in developing countries

Give others an opportunity that was given to us

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PROBLEM STATEMENTPROBLEM STATEMENTBuild a portable device that:

Keeps a 5-mL fluid volume at 10°C (outside temperature 20°C) for up to 12 hours,

Operates without electricity or outside fuel,

Can be manufactured for less than $0.20 per unit (500 units for less than $100),

Does not require highly skilled labor to assemble.

Engineering World Health: Cold Box (Group 19)

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ASSESSMENTASSESSMENT Determine a unique and efficient way to sustain 10°C for 12 hours

Will ice work? CO2

Freon

Decide which materials are good conductors and which are good insulators

Ultimately determine which materials are both sufficient and cheap, and can be easily produced in the developing world

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Initial Design: Initial Design: Prototype Cold Prototype Cold Box Design SpecsBox Design Specs

Outer layer / casingOuter portion of container must be a good insulator (i.e., be an intrinsically poor conductor.)

Ideal materials: Styrofoam Ceramic Gas sandwiched between two layers

Materials chosen: Styrofoam with a durable plastic covering

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Initial Design: Initial Design: Prototype Cold Prototype Cold Box Design SpecsBox Design Specs

Heat sinkCold Box must have a component to remove heat from box contents

Ideal materials: Non-toxic, non-abrasive chemical reaction Heat-absorbing material with large heat capacity

Materials chosen: Ice and water Sodium bicarbonate / acetic acid system

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Initial Design: Initial Design: Prototype Cold Prototype Cold Box Design SpecsBox Design Specs

Inner casingCold Box must have an inner layer to separate the contents of the box from heat-sink materials, yet still allow for efficient heat transfer (i.e., have high conductivity).

Ideal materials: Non-reactive metal Glass

Materials chosen: Aluminum

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Initial Design: Initial Design: Prototype Cold Prototype Cold Box Design SpecsBox Design Specs

Engineering World Health: Cold Box (Group 19)

storage cavity

heat efflux

heat sink

heat-conductive inner wall

insulating outer wall

a + b + Δ → c

Schematic descriptionIn the cold box, an endothermic chemical reaction (generalized here) consumes thermal energy, thus drawing heat out of the inner cavity. This heat is trapped in the heat sink because of the outer insulating boundary.

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Initial Design: Initial Design: Prototype APrototype A

Outer layer / casing: paper-plastic composite (mostly paper)

Inner-chamber layer: aluminum

Heat sink: Binary mixture described below

Cooling Technique: mixture of water (267mL), NaCl (10g), ice

Measuring Technique: LabWorks thermistor-based temperature probe

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Initial Design: Initial Design: Prototype APrototype A

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Initial Design: Initial Design: Prototype A DataPrototype A Data

Engineering World Health: Cold Box (Group 19)

Duration where temperature stayed below 10 °C / 50 °F:22 min for air, 24 min for vial

Problem: Must stay at temperature for 12 h

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Initial Design: Initial Design: Prototype BPrototype B

Outer layer / casing: polystyrene-air-polystyrene sandwich

Sealants: Gorilla Glue and reflective duct tape

Inner-chamber layer: aluminum

Heat sink: Binary mixture described below

Cooling Technique: salt-ice bath [NaCl] = 0.48 M

Measuring Technique: LabWorks thermistor-based temperature probe

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Initial Design: Initial Design: Prototype BPrototype B

Engineering World Health: Cold Box (Group 19)

Inner chamber

Coolingmixture

Lid

Insulatingtape

Nested foam cups

Trapped air

Trapped air

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Initial Design: Initial Design: Prototype B DataPrototype B Data

Engineering World Health: Cold Box (Group 19)

Duration where temperature stayed below 10 °C / 50 °F:3.8115 h for air (+1036.3 % from previous)3.9787 h for vial (+991.7 % from previous)

Problem: Even with better insulation, must stay at temperature for 12 h

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Initial Design: Initial Design: Prototype B CostPrototype B Cost

Engineering World Health: Cold Box (Group 19)

Material Cost Cost Unit Quantity Cost

Styrofoam $0.016 /cup 1 $0.02

Styrofoam $0.043 /lid 1 $0.04

Aluminum Can   /can 1 $0.00

Insulating Tape $0.227 /yd 0.26 $0.06

Gorilla glue $0.722 /oz 0.5 $0.36

Total cost for Prototype B: $0.48

Challenge: Amount is over double what one unit should cost.

Solution: Develop theoretical model to help maximize efficiency while minimizing necessary materials (and thus cost)

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PASTPAST WORK WORK Finalized NCIIA proposal and began regular meeting with advisor.

Agreed on overall design approach: chemical reaction for cooling

Developed lab protocols and secured lab space

Designed and fabricated two prototypes (A and B) and collected data on their efficiency at cooling

Compiled cost data on materials

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CURRENTCURRENT WORK WORK Creation of theoretical model for device using heat

transport principles

Creation of theoretical predictions for most effective chemical heat sink using physical chemistry principles (reaction thermodynamics / colligative properties)

Awaiting reply from Dr Malkin regarding questions gathered in past presentations

Prototype C design

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FUTUREFUTURE WORK WORK Fabrication of Prototype C

Lab testing of Prototype C

Application of theoretical-model outcome to designs

Make appropriate changes to our design paradigm based on Dr Malkin’s response

Toy around with an easier way to manipulate polystyrene and increase its insulating efficiency

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FUTUREFUTURE WORK: Prototype C WORK: Prototype C

Engineering World Health: Cold Box (Group 19)

storage cavity

Extra thick insulating outer wall

Environmental heat sink

Storage-cavity heat sink

heat-conductive inner wall

insulating outer wall

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