Final Presentation

We capped the semester off by presenting the cooler in the BYU - Idaho Capstone open house. It was a lot of fun to show off the cooler and teach people about the technology we used. There aren't very many people who understand how a thermoelectric module works.

It has been a relief to be done with the cooler although I do miss the excitement of trying to continually improve the concept. We'll see what changes may come about in the future.....

Displaying additional thermoelectric modules and we even filled a small container with dry ice to demonstrate how a thermoelectric module can be used as a thermoelectric generator to produce electricity.
Displaying step-by-step pictures of our cooler building process
The final product...

Cooler Testing: Dry ice leak test

I used hot water and dry ice to fill the chamber with vapor. The hope was that after shutting the lid the vapor would show us if we had any leaks.

If you look hard you can see vapor pouring out of the bottom of the hot air exhaust vent. This is not necessarily a good thing.... haha. This was only happening on one side of the cooler. I am assuming this is due to the fact that we replaced the module on that side. In the process of replacing the module we must not have sealed the foam together as well as we should have. We'll know better next time.

Hayden and I having fun with the dry ice. We couldn't resist but have a little fun with the left over dry ice.

After completing this test we conclude that the cooler as failed the leak test.

The test specifications required the cooler to be completely air tight. The ironic information that the test provided is that the lid sealed very well. It sealed tight even after our "slight" modifications.

Finished Product

Testing the solar panel: I tested the voltage coming out of the panel and we were at right around 22 volts. This feeds into the charge controller and then charges the batter at 12 volts.

Side View: Here the black weather stripping is visible. The black actually adds a nice accent to the white cooler.

We placed the final acrylic section into the lid this afternoon.

We finally finished the modifications on the cooler this afternoon. We placed a piece of black weather stripping along the front side to help seal the lid tight. We also placed the last piece of acrylic into the lid. All in all it looks really good and turned out better than we expected.

Solar Powered Cooler Thermal Imaging Test

In order to better understand where our possible losses were occurring we needed a thermal imaging camera. The local Rexburg Police Department was kind enough come take some pictures for us with their camera. Interestingly enough our loss are occurring in areas in which we would have never guessed!

Although it may be too late in the game to make any changes to correct these areas it has been very helpful to understand how and where we can improve on our design.



Image 1: This is a front view of the Igloo cooler with the lid shut. The bright points are "hot" points on the picture (relatively speaking). The dark areas or the cold points. We had the lid cracked just a bit as to allow the dry ice the ability to escape without popping our lid off. For that reason you can see the area around the lid is almost black. Also, the bright spots towards the top of the lid are simply hand prints from people opening it up. The point of interest in this image is the dark square on top of the lid. In the original cooler that is a simple access lid which allows you to open up a smaller lid grab your soda pop out of whatever instead of having to open up the entire lid. Well, that access point happens to be hollow plastic! We have sealed in the back side of that lid with foam but the lid itself remains hollow. You can see the impact that the lack of internal insulation has on the actual heat transfer through the lid.

Thermal Image 2: This is a side shot showing the fan, 2 hot air exhaust ports, and discharge spout. From this angle you can again see the dark square on the lid. You can also see the hot air exhaust ports are bright white. The fan appears the same probably because the heat sync sits right behind the fan. We're actually seeing the heat sync rather than the fan. The most interesting item in this shot is the discharge plug underneath the fan (It is hard to see in this image). The discharge plug is almost black! Similarly to the small access point on the lid this plug has been foamed in.

Solar-Powered Cooler Acrylic Box

This is just a quick update on the housing process. We finished caulking in the reaming portion of the box. We still need to mount our acrylic housing on the lid portion.

Completed Acrylic Housing

Inside view of acrylic box w/ visible thermocouple.

Testing update

This is data we gathered last night from our "maiden voyage". We ran the cooler all night off of a 12 - volt car battery. We also a battery charger wired to the battery as to not completely kill the it off. The initial box temperature was at 66 degrees F. Our original set point for the interior box temperature was 35 degrees F. It hit that set point in 2 hours (15 degrees/hour). I then lowered the set point to 32 degrees F. It quickly brought the temperature down to 32 degrees F where it continued to maintain that temp throughout the night. The bumps in the graph above represent the point at which the box temp has it the set point. At that time the modules turn off. When the box temp again rises above the set point the modules kick on to bring it back down.

The next task is to determine how well it will function with only one module running rather than two. This is especially important because when the solar-panel is connected only one module will be running. We'll see.....

Interior Box update / Testing

Measuring out the acrylic lip dimensions

The whole cooler

Modified lid stop

Ready for testing

Thermocouple interior mount

Data logger ready for logging

Current interior box temperature (Degrees F)

We are getting close to finishing up the inside of the cooler. We have all of the acrylic cut and painted. All we have left is to mount it into position. One key step was to get rid of Igloo's lanyard which keeps the lid from opening too far. It was a simple fix. With the wiring complete and the interior housing almost complete we decided to do some preliminary testing. We set the cooler up in the laundry room (~ 72 deg F). We activated both modules and set the data logger inside the chamber. The initial chamber temperature was 66 deg F. We are going to let it run all night to see how it functions. We'll see in the morning.

Electrical Wiring Part II

Junction box ready to be mounted

Wiring block complete with 3 2 pole relay bases and 2 terminal blocks

The wiring block "wired"

The mounting process

The finished product! Complete with battery leads out the bottom of the box and the solar panel leads out the top of the box.

Top of the junction box: 2 module switches and a charge controller

For the first build our cooler simply used TE module 1 and fan set 1. Also, we did not really incorporate the circuit for solar panel either. Our next step was to wire up the entire circuit, test it, and finally make it look good. I purchased am (8" x 8" x 6") junction box housing from Lowes wherein we would mount all of our wiring. I also purchased new terminal blocks. After reconstructing our wiring schematic in Visio, I drew up the wiring diagram in AutoCAD LT (2009 if you care). With both of those pages as our guide we went to work wiring everything up. Due to time and financial constraints we were using 3 donated relays when really we could have used just 2. We needed a total of 5 poles for the circuit. We have 3 2 pole relays. Essentially what happens is this:

• the cooler will turn on if the main power switch is on AND if the temperature controller concurs that the interior box temperature is above the set point.
• Only one module will turn on if only the solar panel is connected. This module should be able to maintain the box temperature at less than 40 degrees in 80 degree temperatures. As long at it is sunny of course. If the box temperature is sufficiently cold than the solar panel will charge the battery (if it is connected and if the right switch is on).
  
• If the battery is connected (12 volt/70 Ahr) then the user can decide if he wants one or two modules running. Ideally the only time you would need activate two modules would be to bring the box temperature down. You could avoid the excess battery drain of both modules by placing cold items into the cooler or by adding ice. A switch controls the activation of module 2. If this were a product we were mass producing module 2 would be activated at the time the user supplies an exterior power source (12 volt car adapter / AC home adapter).
  

After getting our logic all straight we wired it up and mounted the block to the box and the box to the cooler (easier said than done).

Solar-Powered Camping Cooler Day 5

Day 5:

Due to the time crunch I was unable to construct decent exhaust ducts for the hot and cold air. We spent Saturday digging out foam and constructing quality exhaust ducts. Things were going well until we tried to re-spray foam into the sections we had cut out. We used a common crack sealing foam thinking it was similar to the DOW Froth-pak. We assumed wrong. From the pictures you can see how well the foam turned out. We decided to continue on with the project and fix our foam problem later.

The next step was to construct our interior housing. We cut the side panels first and also cut the duct cut-outs for the interior fans. Then we bent the remaining section of the box. The last step was to paint the acrylic. We chose to paint it in order to hide the yellow interior foam color. We finished the day after we painted the acrylic sections.

Cutting out the old ductsThe interior ducts

Foam job #2: Filling the sections we cut outThe results of our second foam jobCutting the interior ductsEnd sections paintedPrepping the acrylic for bending

Painting the interior box

First Build: Solar-powered cooler

The first build was due today. The class thought it was pretty cool, no pun intended, but there is still a lot of work to do. We let the small module run off of battery power for about 1/2 hour. It lowered the internal temperature from 62 degrees F to 54 degrees F in that time. I guess that is pretty good considering the fact that we need to patch a hole that connects the heat sync exhaust duct and the cold sync exhaust duct! We should have a minimum of an inch of insulation between those two ducts. I must say I think the temperature controller is a great feature to have. It is nice to know the internal temperature at all times. It is also nice that it turns the modules on and off according to your temperature set point.

Solar-Powered Camping Cooler Day 4

Dual terminal block with two-pole and single pole relays

Top View: Wiring layout
Finished cooler housing

Day 4 was entirely focused on wiring all of the switches and controllers together using relays. For the Tuesday deadline, only an initial prototype is required. For the final build the team will purchase two three-pole relays to complete their cooling system. As of now the cooler only runs off one module using battery power. The module turns on only when the on-switch is in position and the temperature controller calls for power. Eventually the cooler will be cooled using two modules when AC/DC power is connected and only one module when solar powered is connected. The system is designed to maintain an internal temperature of < 40 degrees F in an 80 degree F environment.

Stay tuned as the next steps include attaching and wiring the solar panel, connecting the additional module, and cleaning up the wiring and interior housing. All this before the final build is due April 9, 2009.

Solar-Powered Camping Cooler Day 3

Top View: Reverse polarity switch

Top View: Cooler prepped for foaming


Foamed-in cooler

Day 3 started early. I arrived at JBT AeroTech early to spray the foam. After receiving some additional assistance on wiring the polarity switch I sprayed the cooler, carved out external exhaust ducts and then headed home to finish the rest of the project on Monday.

Solar-Powered Camping Cooler Day 2

External exhaust port (incomplete)
Internal wiring layout

Suface mounted switches and controller (On/off, polarity, temp controller)

Day 2 started out well but quickly slowed down. After a successful night of mounting the modules the next task was to mount the switches. I was back at JBT AeroTech on day 2 and I again received helpful advice.

After the switches were mounted I turned my attention to the electrical circuitry. I was lacking a 3 pole 12-volt relay and driving all around Ogden (Utah) didn't prove to be helpful in locating the relay. As the day went on it became apparent that I was not going to have the internal electrical wiring complete for the morning foam spray.

I decided to pull all of the internal wiring to the exterior so I could pour the foam and then address the electrical situation later.

I also needed to complete the external exhaust duct system before I could spray in the morning. These tasks took me all night/morning to the point where day 2 quickly turned into day 3.

Solar-Powered Camping Cooler Day 1

The three cooler models (82 Qt. Coleman Ultimate Xtreme (Green), 100 Qt. Coleman Xtreme (Blue), 120 Qt. Igloo cooler (White))

A collection of all our equipment ready to be installed into the cooler

Brainstorming as to where we should put the 7.5 Ahr battery

Using the hole saw to mount the clear the way for the hot-side fan intake

One module assembly mounted up nice and snug inside the cooler... nice!

The first step was to pick between the 3 different styles of coolers we had received from Coleman and Igloo. We chose the Igloo 120 Qt cooler due to its large size and similar insulating qualities with the Coleman Xtreme series. We were going to need to add additional insulation to whatever cooler we chose in order to minimize heat losses. For this reason the bigger cooler allowed us to add more insulation and still have around ~ 40 -50 Qt capacity. The big accomplishment of the day was to mount the modules into the cooler. I received some mounting advice from a friend at JBT AreoTech which proved to be a great configuration. After drilling though the plastic and insulation things mounted up nice and solid. It made for a late night and a few bloody knuckles but it was worth the effort!