Heat Transfer Device For Off-Grid Medical Sterilization William Dunk David Luker Samuel MajorDaniel...
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Heat Transfer Device For Off-Grid Medical Sterilization William Dunk David Luker Samuel Major Daniel Rist Mechanical Engineering [email protected] The Problem: Unsterile Medical Equipment in Off- Grid Developing Countries • 1/5 of humanity lacks access to electricity (International Energy Agency 2009) • Off-grid medical clinics unable to sterilize tools • Infectious diseases spread rapidly throughout communities • Rural Pakistani clinic: 94% observed injections involved unsterile syringe…44% of these patients tested positive for Hepatitis C (World Health Organization 2000) • We have designed a thermally powered heat transfer device that will be able to operate an autoclave to sterilize medical tools in off-grid locations Our Solution Production of Thermal Power • Curved mirrors reflect sunlight on to water filled pipe to produce steam at up to 165°C and 6 bar • Proven deployable system: currently utilized in Haiti for cooking • Can be expanded to increase capacity (greater steam output) Acknowledgements Our Design Testing and Results Design 1 Design 2 *Design Inverted to Show Details Heat Transfer Device Design Criteria • Heat transfer device must be able to power an unmodified, commercially available autoclave o All-American 1915x autoclave • Heat transfer device must be powerful enough to meet Centers for Disease Control steam sterilization standards o Autoclave must maintain an internal temperature of 121°C for 30 minutes • System (power source + heat transfer device) must be completely self-sustainable o Thermal power requires only the sun • Heat transfer device must be economical and practical for deployment to developing countries o Total cost of device must be less than $200 Design 1 • Maintains 121°C for 30 minutes • Biological test results: negative o Biological spores neutralized o Effective steam sterilization Conclusions • Our heat transfer device is able to sterilize medical instruments with an unmodified autoclave per CDC requirements • Our system is completely self-sustainable requiring only the sun and water • Our heat transfer device is economical with a total cost of $175 • Our system is a promising solution to the medical sterilization problem currently affecting the 1/5 of humanity who currently live in off-grid locations • Steam from Capteur Soleil enters aluminum plate at “steam inlet” • Steam travels through grooves, heating aluminum plate by convection • Autoclave rests on top aluminum plate, heated by conduction • Autoclave and plate are insulated by combination of aerogel, foam and wood with total R-value = 3.45 m 2 K/W = R-20 Front view of Capteur Soleil, designed by Jean Boubour Aramid fiber gasket with SBR rubber binder for steam (0.4/1.6 mm) Bottom aluminum plate (9.5 mm) Top aluminum plate (9.5 mm) Power Results • Power testing was conducted using an electric steam generator to maintain a constant pressure • Plate designs 1 and 2 were tested with gaskets of 0.4 mm and 1.6 mm thickness • Global F Test conducted at significance level of 0.05 • F statistic: 11.64; .0001 < critical-value < .001 • Data provides sufficient evidence to conclude there is a difference among plate design and gasket thickness with respect to mean power output • t test conducted at significance level of 0.05 between gasket thicknesses o t statistic: 6.05; critical value < .001 o Data provides sufficient evidence at the .05 level of significance to conclude that the .4 mm and 1.6 mm gaskets differ in their mean power output o 1.6 mm gasket yields 95% greater power output ANOVA Table for Power Output Source df SS MS Between plates and gaskets 3 54144.23 18048.08 Within plates and gaskets 16 24811.09 1550.69 Total 19 78955.31 • t test conducted at significance level of 0.05 between plate designs o t statistic: .305; critical value < .40 o Data does not provide sufficient evidence at the .05 level of significance to conclude that design 1 and design 2 differ in their mean power output o Plate designs 1 and 2 have equal mean power outputs Sterilization Results Groove dimensions: 6 mm deep x 4.75 mm wide Groove dimensions: 4 mm deep x 3 mm wide GETINGE 24 hour biological test pack Medical tools not properly sterilized All-American 1915x autoclave Insulation container (43 cm x 43 cm) Dr. Douglas Schuler Joe Gesenhues Jean Boubour Attempt at sterilization: sunlight exposure Photo courtesy: Dr. Fischer-Hoch, UTH, Brownsville
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Transcript of Heat Transfer Device For Off-Grid Medical Sterilization William Dunk David Luker Samuel MajorDaniel...
Heat Transfer Device For Off-Grid Medical SterilizationWilliam Dunk David Luker Samuel Major Daniel Rist
Mechanical [email protected]
The Problem:
Unsterile Medical Equipment in Off-Grid Developing Countries
• 1/5 of humanity lacks access to electricity (International Energy Agency 2009)
• Off-grid medical clinics unable to sterilize tools
• Infectious diseases spread rapidly throughout communities
• Rural Pakistani clinic: 94% observed injections involved unsterile syringe…44% of these patients tested positive for Hepatitis C (World Health Organization 2000)
• We have designed a thermally powered heat transfer device that will be able to operate an autoclave to sterilize medical tools in off-grid locations
Our Solution
Production of Thermal Power
• Curved mirrors reflect sunlight on to water filled pipe to produce steam at up to 165°C and 6 bar
• Proven deployable system: currently utilized in Haiti for cooking
• Can be expanded to increase capacity (greater steam output)
Acknowledgements
Our Design
Testing and Results
Design 1 Design 2
*Design Inverted to Show Details
Heat Transfer DeviceDesign Criteria
• Heat transfer device must be able to power an unmodified, commercially available autoclave
o All-American 1915x autoclave
• Heat transfer device must be powerful enough to meet Centers for Disease Control steam sterilization standards
o Autoclave must maintain an internal temperature of 121°C for 30 minutes
• System (power source + heat transfer device) must be completely self-sustainable
o Thermal power requires only the sun
• Heat transfer device must be economical and practical for deployment to developing countries
o Total cost of device must be less than $200
Design 1
• Maintains 121°C for 30 minutes
• Biological test results: negative
o Biological spores neutralized
o Effective steam sterilization
Conclusions• Our heat transfer device is able to sterilize medical instruments
with an unmodified autoclave per CDC requirements
• Our system is completely self-sustainable requiring only the sun and water
• Our heat transfer device is economical with a total cost of $175
• Our system is a promising solution to the medical sterilization problem currently affecting the 1/5 of humanity who currently live in off-grid locations
• Steam from Capteur Soleil enters aluminum plate at “steam inlet”
• Steam travels through grooves, heating aluminum plate by convection
• Autoclave rests on top aluminum plate, heated by conduction
• Autoclave and plate are insulated by combination of aerogel, foam and wood with total R-value = 3.45 m2K/W = R-20
Front view of Capteur Soleil, designed by Jean Boubour
Aramid fiber gasket with SBR rubber binder for steam (0.4/1.6 mm)
Bottom aluminum plate (9.5 mm)
Top aluminum plate (9.5 mm)
Power Results• Power testing was conducted using an electric steam generator to maintain a
constant pressure
• Plate designs 1 and 2 were tested with gaskets of 0.4 mm and 1.6 mm thickness
• Global F Test conducted at significance level of 0.05
• F statistic: 11.64; .0001 < critical-value < .001
• Data provides sufficient evidence to conclude there is a difference among plate design and gasket thickness with respect to mean power output
• t test conducted at significance level of 0.05 between gasket thicknesses
o t statistic: 6.05; critical value < .001
o Data provides sufficient evidence at the .05 level of significance to conclude that the .4 mm and 1.6 mm gaskets differ in their mean power output
o 1.6 mm gasket yields 95% greater power output
ANOVA Table for Power OutputSource df SS MSBetween
plates and gaskets
3 54144.23 18048.08
Within plates and
gaskets16 24811.09 1550.69
Total 19 78955.31
• t test conducted at significance level of 0.05 between plate designs
o t statistic: .305; critical value < .40
o Data does not provide sufficient evidence at the .05 level of significance to conclude that design 1 and design 2 differ in their mean power output
o Plate designs 1 and 2 have equal mean power outputs
Sterilization Results
Groove dimensions: 6 mm deep x 4.75 mm wide
Groove dimensions: 4 mm deep x 3 mm wide
GETINGE 24 hour biological test pack
Medical tools not properly sterilized
All-American 1915x autoclave
Insulation container (43 cm x 43 cm)
Dr. Douglas SchulerJoe GesenhuesJean Boubour
Attempt at sterilization: sunlight exposure
Photo courtesy: Dr. Fischer-Hoch, UTH, Brownsville
