Solar powered melting machine

Hello Guys,

I am a German living in a Colombia. I am in a project with some friends to start a comunity in a jungle on the sea.

I am very concerned with all the plastic waste arriving to the beaches and thought make it an advantage using it as building material for houses like roofs and beams. Also use it to make artwork.

I would like to create a very simple solution using sun light to melt the plastic and to bring it to the form we need. Also no using electricity. I want it to be very simple and cheap to make it available to the poor people arround, so they can have a benefit from it, and thus clean up the sea from the plastic waste.

If you can give me any direction on my study, I would be more than greatful.

Thank you

Sounds like a great and doable plan! Haven’t tried solar heating though… I guess the injection machine is best suited for this purpose.
Good luck and keep us updated

It’s a great idea to utilize solar energy for heating the plastic. I believe that you need some control system or at least measurement for the temperature? Since different kind of plastic have different melting point. Has anyone made this solar heating into realization? Or any more info about this?
I happen to live close to the equator, which gives me plenty of solar energy. So I’m very much interested.

I thought this was an interesting concept for making less expensive solar collectors for melting plastic.
That cheap solar heater for high temperatures 200 ºC (HT solar collector-concentrator) Sergiy Yurko

Using thermal transfer oil and an insulated tank, make a plastic melting oven.

I am working on recycling used plastic mulch into pavers and roofing tiles using sand and heat.

I have a concept of using a heated drum roller to mix courser plastic particles into a homogeneous blend before adding sand.

here’s a very interesting article on the topic. evtl. the engineers here on board can make some predictions whether this could heat up an extrusion

This is a project I am also interested in. I have had some success melting certain forms of plastic using solar energy focused by a simple makeup mirror as you can see in these videos:

I am however seeking other like minded individuals that may be able to solve various problems and give suggestions as to improve this process and make it simple for anyone to melt plastic and mold it for various purposes.
Feel free to contact me here if you have any suggestions.

Hi. I am working in an extruder similar to Precious plastic extruder, but I try to put  a satellite dish (parabolic) in the barrel for concentrating light purpose, instead the heater band elements. Then, I will use a heliostat for redirect the sunlight to the parabolic dish. I build all this stuff from trahs, literally. If you interested send me a message, Im still work in this project. Greeting from México!

check this out for a low focal length mirror (parabolic). This guy uses metal coated mylar film as a reflective surface.

alright i will look into it. I will see if i can do it for a university project. as we have alot of solar collectors sitting around. However the cheapest to do right now is use like aluminum foil and a curved piece of aluminum.

Energy is known to be more clean when less steps are required to produce it.
You blew my mind with this idea. It needs some calculations and some heavy equipment. But the end result (zero energy bill, zero CO² emissions) is really worth it.

You should be making some tests using a Fresnel lens or a reflector, before setting some heliostats for more efficiency.

For sure there is a market for a thing like that!

Access to electricity is a real problem in unindustrialized countries where the waste problem is almost the greatest. I think it would be a bit of a sensation.
Are you serious you think it could work?

O you guys foreal want to see one? i mean if there is a market for it i can try building it.

@thegreenengineers @davehakkens
As soon as I learned of the “container shop” I thought about it being solar-powered. It surely is something that for instance African countries have plenty of…
Looking forward to seeing this take shape.

Ok so lets talk about some pressures and temperatures at each point using more practical numbers

  1. (Starting Point) Temp = room temp 25C Pressure= 1 atm (~ 15PSI, ~100Kpa)
  2. need to solve for
  3. need to solve for
  4. 100c at 1 atm
    Enthalpy for each step
    1)419.098 KJ/KG
    2)need to solve for
    3)need to solve for
    4)2675.76 KJ/KG
    ok so we can get our hands on 1m^2 Fresnel lense and 875 watts of power
    lets solve for how much steam mass flow rate we can make with that
    solve for mdot
    .875/(2675.76-419.098)= .0003877 KG/sec of steam
    We want to have a output of about half a horsepower to run the shredder. so 372.85 watts which is about 40% effeciency
    solve for h3
    (Qdot/(mdot)) + h4
    (.37285/(.0003877)) + 2675.76) =3637.5 KJ/KG
    so at 50 psi we need a temperature of 423 celcius (increase of 300C)
    to make half a hp.

ok so how much plastic can we melt from point 4 to 1
Q=Cp*mdot*(Tmelt – Tenviroment)
solve for mdot
Q/(CP*(Tglass-Tenviroment))= mdot
.37285/(2.4*(126-26)) = .001553 KG/Sec
.0932 KG/Min or 5.592 KG/Hour or 33.55 KG/6 Hour Work Day

So process 33.55 KG of plastic per day and Shred plastic with at 1/2 HP motor. Using a 1m^2 Fresnel lens, the sun, and a used car turbo.

ok so maybe i will do the first calculation for a steam powered shredder and melting machine.
First we have to decide what our temperature high and temperature low we want
we can determine this by looking at the maximum efficiency that we want
maximum effeciency of a thermal cycle is know as a carnot cycle
a carnot cycle is a ideal 100% efficient use of the heat you have without any leakage
the equation is ((Th – TL)/Th)*100 output is a percentage which shows our maximum efficiency
Plugging in this into a graphing calculator we can plug in Th to find a temp we want
For Tl we are going to go with 25 Celsius (environment temp)
727 celcius is 70% efficiency lets go with that

A steam engine is also known as a Rankine Cycle
there are 4 steps to the cycle minimum
1st: water at room temperature is brought into water pump to increase pressure
2nd: water is sent to boiler to be heated at constant pressure into water vapor (phase change)
3nd: Water is expanded in a turbine (drop in temp and pressure aka energy loss)
4th: Water is condensed in a heat exchanger to change the phase from vapor back to liquid
Then cycle completes indefinitely

So maybe find a mechanical pump that is powered by the excess would be nice so now electric power is needed thi would be powered by the second stage
A 18 wheeler turbo would be used for a turbine and output shaft to drive shredder
A third stage turbo could be used to drive a continuous extruder or something

So to calculate the power generated and isentropic efficiency
You do so by calculating the pressure and temperature at each of those stages
then using those pressures and temperatures you use a saturated steam table
to look up the specific energy that the water contains known as enthalpy
by knowning the enthalpy at each point and the flow rate of water from the pump
you can solve for the hp and the efficiency

@thegreenengineers, good, keep us updated 🙂

Maybe i could run some calcs off what he and I have (cali is very similar solar energy as Columbia) as far as parameters. And see what type of energy i could generate. calc for isentropic efficiency, HP, Torque, turbine efficiency, material process rate in both the shredder and extruder etc. and mabye a rough sketch of what it would look like. I might integrate that into my senior engineering project next year for off the grid recycling farm. Because for most productive circumstances solar panels are terrible.

this would be a pretty cool project

@thegreenengineers, sounds pretty cool indeed, are you going to try develop it?

Use like a water tank that is heated with a 1m^2 into boiling to turn it into steam
Then have a turbo out of car expand the steam to generate rotation and torque.
That torque to turn the shredder
Then to change phase back into liquid suck away the heat by using it to melt the plastic.
Then maybe use another turbo as a turbine to turn a constant extruder.
this would be a pretty cool project

Keep me updated interesting in seeing the design. what would be sweet is if you used solar steam engine design to power it. Did you know that steam engines are about 4 times as efficient as solar panels?
It would be super cool if you used the plastic melting to condense the vapor back into water. and used the steam turbine to drive the shredder.