Product Design Methodology
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• Design Criteria
• Concept
• Sub-Systems
• Timeline

• Temperature Stabilization
• Vaccines must be stored between 6 ± 2 ° C

  Our concept seeks to improve temperature stablization and capacity of the parts of the cold chain currently served by the cold box.

• Ambient Temperatures of 43 ° C and 27 ° C for WHO tests
• Capacity
• Current Cold Boxes: 250L of space for 25 L of storage
• Portability
  • Road imperfections could cause damage during transportation
  • Potential for long term storage outside the electric grid
• Duration of Storage
  • Store vaccines for at least 5 days
• Easily Maintainable
  • Should not need expert to repair

Our concept employs PCM as a primary form of refrigeration, which is recharged by a small energy efficient compression system.

• Employs PCM in conjunction with compression refrigeration
  
  
• Uses battery for transit, but has an adaptable power supply
  
  
• Allows for resetting of PCM
  
  
• Runs compressor at night to save energy
  
  
• roadens cold chain
  
  
• Potential for implementation as storage
  
  

• PCM
  • Currently selecting and testing PCMs for heats of fusion and thermal conductivity
• Compression
  • Sizing a compression system for this application and looking into eco-friendly refrigerants
• Electric
  • Examining power sources for the system, as well as developing a more sensitve thermistor control syset
• Structure
  • Deciding size, shape and capacity of our prototype, as well as integrating the work of the previous three teams
• Case Study
  • Continuing our background research into the cold chain, to further outline current problems and develop our design criteria further, in order to establish the major holes in the cold chain, so that other innovators may solve them.
• Marketing
  • Currently researching how the market for vaccine refrigerator works, and looking for possible business partners. They will design a marketing plan for our prototype which is appropriate for the public health industry.
• Public Relations
  • Contacting experts and making people aware of our progress

Milestone/Deliverable

Spring 2010

Fall 2010

Spring 2011

Fall, 2011

PCM Team

Characterization of intrinsic properties of PCMs

Identification of concentrations, densities, etc. contributing to intrinsic properties

Selection of PCM to be used for integration

Performance Testing of PCMs in unmodified refrigerator

Calculations of PCM performance in integrated refrigeration system

Integration of PCM with structural, mechanical, and electrical components

S&E Team

Dismantle refrigerator(s) to identify insulation, inner casing, and outer housing

Determine dimensions and materials of insulation, inner casing, and outer housing

Integration of structural and electrical components with mechanical and PCM components

Research sustainable energy sources for low-resource settings including batteries and/or plug-in

Construct prototype with selected energy source

Compare performance of selected energy source

Compression Team

Establish a qualitative and quantitative understanding of the compression cycle

Develop equations to describe heat transfer, cooling capacity, and other performance indicators

Research possible alterations to compression mechanism (e.g., jet valves)

Research alternate refrigerants, including cost, availability, & lifetime

Determine a parts list for compression cycle components

Entire team

Provide design drawings of integrated system (ongoing)

Simulate performance based on selected components using a computer model (ongoing)

Fabrication of integrated refrigeration system

Durability and recyclability testing