156B Week 4

Overview of Status of Analysis, Design, Fabrication, Tests, etc.

• Completed cold side testing.

• Received previous teams prototype

• Ordered mesh vest for prototyping

Accomplishments from Previous Week

• Completed cold side testing

  • • Validated cold side thermal resistance (measured value within expected range)

      • • Can proceed with our choice of tubing for the prototype

    • Tested hot and cold side assemblies under heat load and without heat load

      • Without heat load, achieved reservoir temp ~5 C

      • With heat load, achieved reservoir temp of ~ 18 C (Cooling 58.85 W)

• Radiator stress test (hot side test)

  • • Tested dissipating 159W of power via 6 ohm resistive heating element

    • Thermal resistance values remained consistent compared to previous experiments, validating results for higher heat load

Goals for Next Week (list names after each item). Use specific and measurable objectives.

• Copper plate test. - Tyler

• Redesign jet water block.

  • • Finish Ansys analysis - Josh, Jocelyne

• Run new cooling system with old prototype - Vlad, Edgar

Sponsor Comments from Last Meeting and Actions Taken to Address these Comments

Zoom - 01/22/2021

• We brought up integrating solar panels into the system. Dr. Suarez advised us not to focus on this.

  • • We will not focus on integrating a solar panel.

• Dr. Suarez asked us about battery requirements. He was concerned about its size and wattage.

  • • The estimated total wattage is 35W and the whole system should be within 10A. We suggested using electric skateboard batteries. Dr. Suarez thought that this was a good solution.

• Since the TEC will be in direct contact with water, Dr. Suarez is concerned about it being waterproof.

  • • We are confident that the Peltier is waterproof but will valid this with an experiment.

Instructor Comments from Last Meeting and Actions Taken to Address these Comments

Zoom Presentation - 01/21/2021

• Mentioned that team needs to double-check experimental setup/calibration

  • • May be an error present when calculating thermal resistance

    • (Temp at steady-state - average readings at low power) / power

    • Calibrated themocouples & did not see an error in the system

• Advised that we look into using solar panels since vest will generally be used outside

  • • May be able to provide additional power

    • Researched solar power panel capabilities but it doesn't seem like we will gain an advantage from solar

    • Solar panels in the form factor required offer low power capabilities

      • • One example of a solar charger within our constraints is GoerTek 25000mAh Solar Power Bank $30-40

        • The max solar charging rate is 1.5W (5V,300mA) which is not enough to justify this specific example

        • Not a worthy tradeoff considering the size & weight but may consider if our final battery choice is a similar weight

    • We recommended to the sponsor that we may be able to consider solar charging as an accessory for the vest

• Asked about battery requirements?

  • • We have not completed a power calculation yet but we have a rough idea ~35 W

    • We will get our final power requirement numbers after prototype 1 testing

    • We are currently considering an electric skateboard battery or li-ion battery packs

    • Advised us to look into PWM

      • • We have done basic research in PWM and will consider it as well

Comments from Other Students in the Class

Zoom Presentation - 01/21/2021

• A student asked us about the weight of the whole system. They wanted to know if it would be a comfortable weight to carry while performing physical activity.

  • • The system should not be too heavy. The heaviest component will be the battery. The batteries we are thinking of using are about 0.29 kg The weight of the water will be evenly distributed around the body and should also be less than 0.9 kg (2 lbs).

• A student asked about the amount of water we will be using.

  • • We will be using about a quarter-liter of water on the hot side and about half a liter on the cold side.

Schedule

• • Milestones

    • • First full prototype assembly & test

  • Updated Gantt chart link

    • • Screenshot of the most recent updates included below

Budget (list amount spent and amount remaining)

• Noctua NF - P12 $29.96

• Mesh Vest $22.25

• Amount Remaining: $1215.30

Progress on Report and Webpage

• Completed: Impact on Society

• Completed: Professional responsibility