Introduction: Home Made Freezer Box Fridge/Air Con .
Warning!!! Check your countrys refrigerant handling rules before you attempt this.
If you live in Australia only attempt this if you are an Air con mechanic or Car mechanic with a refrigerant handling license .
If not you can make a system out of a water pump instead.
This Is a guide on how to make a Freezer box powered by a fridge compressor .
This system uses The very basic must have components of a fridge .
Compressor : To pump the refrigerant around the system
Heat Exchangers : These copper coils are used to rejected heat at the condenser and absorb heat and the evaporator
Metering device : This Is a must have component , to meter the liquid refrigerant into the evap coil and to created a pressure drop .
Refrigerant Gas : This 134a Gas which is used in most cars fridges/freezers , Its used to create a reversible phase change from a liquid to a gas . In the evaporator the gas changes from a liquid to a gas , In the condenser the opposite is done. When it changes state like this it either gives of or absorbs heat .
The basic idea of this system is to keep ice water cool at temps bellow freezing .
The coils are submerged into water . The Cooler box has been split into two parts .
The condenser on the right gives of heat and makes the water warm .
The water is changed when it the temp gets to high . Or can be set up to slowly drip new water in while dripping and the same rate the warm water.
Ive used water as the medium instead of air . so there is no hot air coming out of the system.
Step 1: Tools and Materials
A Brazing device either a hand held torch or an oxy set.
Copper tube cutters
Conduit cutters or a hack saw
1/4 copper pipe ( DO not use plastic or anything else with refrigerant gas!)
A Cooler box or a Styrofoam box
A fridge or freezer compressor ( Remove from an old fridge one that has lost its gas already )
A hand valve or a capillary tube
Pvc Pipe glue
Step 2: Piping Up the System
I used 1/4 copper pipe . I Made the condenser on the right square to fit in more . I used pipe benders to make this shape , You can get a similar bend with your hands its pretty impossible to kink 1/4 pipe . You could also keep the coil round .
The coil comes in roll about 300 diameter . I made the coil abit tighter by bending it just a tiny bit every so often .
You could also have the condenser in a separate tank . A round bucket and keep the coils round .
I used old gauge hoses just to make it abit more portable and easily dismantled . Also the only hand vavle i had at the time only fitted on hoses .
I would recommend just using copper all the way. And making the condenser coil bigger than i did . Should be around 40% . Normally the condenser is bigger than the evap . But with the water been used instead of air it can be abit smaller .
With the old compressor you have found . Figure out what side is the discharge ( the red hose in my pictures) and what side is the suction ( the blue hose).
The smaller pipe coming out will be the discharge and the bigger the suction.
Following the Diagram bellow .
4 is the compressor the discharge pipe then goes to the (1) condenser
the outlet of the condenser then goes to the metering device( hand valve) .
The gas then travels to the evaporator as cold vapor.
The outlet of the evaporator is The suction pipe.
I have cut in little notches with a hack saw blade so the lid closes and doesnt hit the pipes .
Step 3: Running the System.
You should also Vac the system out before adding gas. To stop moisture freezing up at your metering device.
You need Add gas before you can run the system .
The system that you removed the old compressor should say how much gas it took. This is only an rough idea .
The system i removed my compressor from took 80grams . 0.08kgs not much at all . Slowly add the gas until the system is running well.
I ended up adding 65grams of gas.
You will have to play around with the hand valve until you get the system running coldest . Open it up a tiny bit until you can hear gas going through . 95% closed.
I have picture of the coil iced up with about half of a inch of ice around it , but cant get the upload picture thing working atm.
Step 4: Adding Air Con Mod
I have not had time to do this step yet .
But the idea is to have a Spiget onto the lid of the box so i can tape 300mm duct onto the back of the fan.
The water in the evap side is only half full . So retangle holes can be cut around that size of the box .
Air will be sucked in through these wholes and the cool air from the freezing water will blow out of the fan.
Step 5: Extra Notes and Info
The temps of the system are as follows.
0c is freezing temp of water .
Water temp after 20 mins .
Evap coil temp
Condenser water temp if no fresh water going in after 20 mins
38c on the top inch of the water then about 30c under this.
Condeser Coil temp
Ive been putting the waste warm water into my washing machine . You could wait over night if you have 2 buckets and the water would be cool again .
Things i would do different , if i had a drain hose on the condenser near the top . to drain the top hot water . There seems to be a hot layer of water on top which gets thicker over time. If this water was changed instead of the colder water at the bottom it would work better.
The metering device is hard to calibrate correctly . It would be to hard to get a perfect length and bore of capillary tube but something close would work.
The charge of gas is just a guess, The perfect amount takes awhile to calculate .
Can the first few posters tell me if i have made any grammar mistakes or any more info i should add