Solar Powered Chiller

For the final project I’m planning to build a Solar powered chiller to complement our main theme of “Heat for good”. Chilling canned drinks or other beverages is a common need of many people specially when they are going out for an outing in a hot environment. In this project I propose a cooling mechanism which uses the compressed air as the coolant and plan to build an experimental prototype. If successful this portable device will be able to chill beverages “on-demand” within few minutes and it will take the burden of carrying heavy mobile refrigerators or cooling boxes off while you are enjoying outdoors.

This proposal is largely motivated by Mitchell Joseph’s work on building a self chilling can.

Self-Chilling can
Self-Chilling can

Theoretical background: 

Amontons’ Law of Pressure-Temperature : The pressure of a gas of fixed mass and fixed volume is directly proportional to the gas’s absolute temperature.

Proposed Setup:



  • The Solar powered air-compressor pumps the air to the copper tube and increase the air pressure inside the tube when it is exposed to the sun light.
  • After the inside air pressure reached a desired level, user can place the drink-can inside the coiled copper tube. (See figure)
  • Then user removes the cap allowing the air pressure to decrease drastically resulting a temperature drop. ( See the theory) This results a temperature difference between the drink-can and the air inside the copper tube. Therefore a heat transfer will happen from the canned drink to air through the wall of the copper tube. An insulating material will be used to cover the copper tube from outside environment to eliminate the heat transfer to the outer environment.

Final Project – Possibilities

I want to make a solar cooker that works really well in the summer and hopefully in winter as well. I have tried to use as many “usable trash” components in my project idea but I would also like to use sheets of metal to make the cooker from scratch. I  don’t have access or the skills required to cut and fold metal and this is the biggest limitation.

I have included doodles from my notes to explain the three possible design ideas. THe overarching idea is to use reflection of solar radiation from as many angles possible to heat a metal sheet which heats up, transfers the heat to materials being cooked. I think of it as trapping heat. When the food is almost cooked I would like to cover the cooker to retain moisture in food as well as use energy efficiently.WP_20151027_09_53_03_Pro1WP_20151027_09_54_53_Pro

The simplest design I have uses a large tin can. The sides of the can will be cut along its length and bent outwards to reflect radiation. The upper cover of the can can be cut to size to use as a lid.


The next design is a bit quirky and uses the frame of a broken umbrella. I intend to place metal sheets or other reflective surfaces along the inner surface of the umbrella. The doodle explains the design better. When finished it will look like flower. This setup is only the arrangement of the reflective surface. The actual cooking can be done in a stainless steel plate with a border of at least an inch. This plate needs to be placed inside the reflective surface setup.


The third design possibility is the one that I shared in class the other day. For this a food grade metal sheet needs to be bent to form an angle between 45 and 60 degrees. Since I intend to cook food  in it there needs to a panel system built around the sides of the v. When food is half cooked the cooker can be sealed from both sides and the top. I will definitely need to use tools and acquire basic fluency with metal work. WP_20151027_09_53_15_Pro

Final Project – Solar Refrigerator

How to: Solar Refrigerator

The hotter it gets, the more important it is for cool food to stay cold!

There are 2 types of solar refrigerators –
the high tech expensive kind
(use a solar panel to power a normal-functioning refrigerator
the also technical but less expensive kind
(uses a coolant heated up by the sun to draw heat out of the refrigerator)
This will be an attempt to create one of the second kind

most common cooling materials: lithium bromide or ammonia

* ammonia is poisonous, so must handle with caution

single-effect devices coefficient of performance: 0.6-0.7
(60 to 70 Btus of cooling for every Btus of input heat)
Btus – British thermal units

some pipe
a bucket of water
some calcium chloride (absorbent)
ammonia or lithium bromide (as refrigerant)
sheet of shiny metal (solar collector)
something with good insulation to work as refrigerator


Solar ammonia absorption ice maker – good pictures, diagrams, & descriptions

Their description of materials and pricing:
Quan Material Cost
4 Sheets galvanized metal, 26 ga. $100
1 3″ Black Iron Pipe, 21′ length $75
120 Sq. Ft. Mirror Plastic @$0.50/sq. ft. $60
2 1/4″ Stainless Steel Valves $50
Evaporator/Tank (4″ pipe) $40
Freezer Box (free if scavenged) $40
1 Sheet 3/4″ plywood $20
6 2x4s, 10 ft long $20
Miscellaneous 1/4″ plumbing $20
2 3″ caps $15
1 1/4″ Black Iron Pipe, 21′ length $15
4 78″ long 1.5″ angle iron supports $15
Other hardware $15
15 Lbs. Ammonia @ $1/lb $15
10 Lbs. Calcium Chloride @ $1/lb $10
Total $510



paper on how to build a solar ammonia absorption refrigerator
senior design project


How to make a solar-powered refrigerator- solar design wiki


absorption refrigerator solar prototype from Chile

Citrus Color as Biomarker for Seasonal Health Status Indicator

As organic beings, biomarkers are always within, on and around us in everyday life. The biomarkers that I pay attention to most outside of my own body-system are often related to season/soil and agricultural biomarkers.

One such system that I care for is a Lemon-citrus tree. I transplanted this tree 5 years ago as a youngling and have maintained, monitored and pruned this tree to produce lemons of distinct and useful flavor. The breed is known as Sorrento as it is from the family of Italian lemons that of which produce the world’s tastiest Limoncelo (a refreshing, alcoholic beverage) enjoyed traditionally off the Amalfi Coast of Italy –


Each fall and spring, I attend to trimming and preparing the tree when it shows signs of adaptation to the next harvest season. Being as the “fall” and “spring” in an arid, temperate, desert climate can vary greatly from year to year, the timing for watering, fertilizing and pruning an tree or shrub can make the difference between a healthy and high volume fruit generation each season and/or a low volume and struggled fruit bearing.


Identifying with the seasonal biomarker (the sun) and it’s movement on the horizon as well as it’s intensity has suggested to me a change from the summer season to the fall. Additionally, temperatures, both in the evening as well as the afternoons have dropped significantly and are indicative of a good time for tending to the fall citrus season.

The most identifiable biomarker for citrus health and growth is the skin coloration of the fruit. The color tone ultimately provides a cue regarding it’s water allocation, soil condition and sun exposure.

In the below example, you can see where the discoloration of the fruit is suggesting a ripening fruit, it is also showing pale signs of yellow vs. a vibrant and healthy “lemony”  yellow. This is a biomarker for early(pre season) fruit development.

Ripened lemon fruit, too early and appearance is thin and underdeveloped.
Unripened lemon fruit looking healthy and plump

A green lemon suggests it is unripened. The vibrancy, and plumpness of this fruit suggests a future ideal lemon is possible here.  These visual “biomarkers” are critical for my ability to maintain and harvest a healthy batch of lemons this year. Albeit, not for Limoncelo (this time), rather for a nice fat lemon cake (see Food Science experiment).

Additionally, I have discovered that the current interest is in respect to identifying diseases in trees using biomarker, genetic and scientific methods:

1) Report of Suggestions on Florida’s Asymptomatic infected trees –

2) Point-of-use nanosensor for detection of citrus greening disease (Huanglongbing) –

It would appear as though some technology exists for identifying citrus health by using computer vision as well as other technologies. Perhaps one could be developed for home gardening use? I also like the idea of designing an infographic for citrus health monitoring as in:

Perhaps one is needed for citrus in AZ?

Experimenting “Kiribath”

“Kiribath” (kiri = milk, bath = rice, hence milk rice) is a traditional Sri Lankan dish made from a special kind of rice called “Kekulu”. Be it rich or poor, Kiribath is an essential dish for any special moment in Sri Lanka, specially in celebrating the Sinhalese New Year. Kiribath is cooked and served as the first meal after the dawn of the new year.

Sri Lankan traditional new year dining table featuring "Kiribath".
Sri Lankan traditional new year dining table featuring “Kiribath”.

To cook a proper kiribath dish we need following essential items; Kekulu rice, coconut milk with right amount of thickness, clay pot and firewood hearth. Since, it is hard to find these exact items in this part of the world, I did an experiment on cooking kiribath using Basmathi rice, canned concentrated coconut milk and a rice cooker.


Even though, basmathi rice is somewhat  similar to Sri Lanka kekulu rice in physical shape, kekulu contain higher amount of water in them. Therefore I made a (kind of) calculated adjustment to the recipe increasing the amount of water per cup of rice. Despite of not having the perfect conditions such as controllable temperature, clay pots, correct kind of rice and fresh coconut milk I was able to cook a kiribath dish which is somewhat similar to what my mom makes back home.


A feature of a correctly cooked kiribath dish is the ability to cut them into trademark diamond shaped smooth pieces. My kiribath pieces wasn’t the best when it comes to shape, but they were almost there.


Through this experiment I realised that the correct conditions, right materials and equipment are key requirements for making a perfect kiribath. Anyway, the kiribath made with the stuff we have here wasn’t too bad both in shape and taste. It was an attempt to be proud of, at least until I hit an authentic Sri Lankan kitchen again!

Final Project Ideas

Usable Trash Repurposing old toys and toy components
Beer bottle hydroponics system

Beer bottle + LED bulb

Instant papier mache
Light saber
Discarded yo-yo used in skirt to light up with a spin
Block printing system
Reflective surfaces art
DIY wagon
Find new purpose for a tooth brush motor
Christmas trees that are not trees
DIY loom
Rainbow maker
Holiday décor
Repurpose plastic bags
Soda can heating system
DIY Bio Vermicomposting kit
DNA extraction kit
Bacterial culture kit
Ginger ale
Fruit ripening system
Art Art machines
Graded thermochromics
LED toys to blinking capes and costumes
Laptop bag with Wi-Fi detector
Seat that lights up when you sit on it
Glow stick creations
Culture Recreate traditional baby carrying systems
Find out, through interviews, what happens to old toys, gadgets, and “stuff”
Interview artists-makers-scientists about their transitions across the interface

In the spirit of sustainability preliminary notes were taken on a restaurant menu.

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Milking Ideas

Milk is a staple in my kitchen and I take its benefits and uses for granted. For this project I have maintained a focus on milk by making cottage cheese and clarified butter at home.

Cottage cheese

I have been making cheese at home for many years now. The milk was fresh from the farm and had very high fat and protein content. I decided to try it with grocery store bought milk and note any differences  in the cheese making process as well as taste. The steps are described through photographs.

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Once milk came to a boil I added about two tablespoons of vinegar to it. Ideally, I would use two litres of milk in a heavy pan and heat it over a very low flame. Milk would reach boiling point in an hour. The surface would have a very thick layer of fats which I would separate and refrigerate for making clarified butter. The cheese was strained through a very soft muslin and refrigerated. The cheese I made was less creamy but tasted quite good. I would give it six out of ten for flavour and texture.

Clarified Butter

As I said, the thick top layer of milk fat is used for making clarified butter. It is a lengthy and messy process but the flavour makes the effort worthwhile. For the project I used unsalted butter. My argument was that it is called clarified butter and so, there has to be a way to make it from regular butter. The following are the steps.

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A small cube of butter was added to a heavy vessel and heated on very low flame. Once the butter came to a boil, light brown froth could be seen at the surface. The brown froth also had some milk solids in it and had to be strained. The resulting clarified butter was dark golden colored and smelled different from the butter I made at home. It tastes and smells good, but in a different way. This could be because of the used butter, and the small portion used.

This is a good way to visualize the number of components in milk – proteins, SNP (Solids Not Protein) and fat.

Final project pitch and proposal

In this assignment you will finalize your project idea. This is a 2-part assignment: you will post your project proposal to the blog, and you will pitch your idea in class.

Project pitch (5 minutes in class)
You will have five minutes to pitch your idea to the class. You can use any format you want (slides, skit, poster, video, etc.). Your goal is to convince the class that your project is a good idea. Since you only have 5 minutes, you have to succinctly explain the vision, problem or opportunity your project fulfills (or how your project fits within our class theme of heat); who might use your project; where it might be used; and why it’s a good idea.

Project proposal
In addition to the pitch, write a more detailed project proposal for the class blog. At the very least, include the following:

  • motivation (similar to the pitch, describe what problem, research question, or opportunity your project addresses)
  • related work (do a quick search to see if other projects have tried to address a similar topic; find 2-3 similar projects)
  • your idea (what you plan to build, who will use it, where it will be used, and why it’s different from existing work)
  • implementation (how you plan to implement your idea)
  • parts list (a tentative list of components you might use for this project)

Post your project proposal on the class blog under the “project proposal” category.

The proposal posted on the blog is worth 4 points and counts towards your final project grade
1 point for describing your project  motivation
1 point for describing related work
1 point for describing your project idea
1 point for adding your parts to this list and descriving implementation details in your proposal

The in-class pitch is worth 2 points and counts towards your final project grade
2 points for clearly presenting your idea in class