Hi there!
Okay, So I am a student who has been working on building a freeze drying machine from scratch for about a year. I have actually had reasonable success with most of the components inside the machine, but believe it or not, all this time and I am still having much difficulty with the "freeze" part of the machine.the amount of info on refrigeration continues to make my head spin. I am really hoping to make a sellable machine, so I am trying to avoid a cascade system, due to extra price and failure mode. There is one other somewhat similar system on the market from Harvest Right who manages to do the deed with a single compressor. the refrigeration coils will be used to condense and freeze water from the air onto the coils. The machine will be well-insulated, and will have a capacity of several pounds of food, containing possibly a half gallon or so of water.
With all this in mind, here are the requirements I need to meet in the refrigeration system:
Be able to freeze product to close to -40 with proper insulation,
Be single stage,
Have a coil big enough to support over a gallon of moisure and still cool.
Have a coil temp greater than 10 degrees lower than the product temperature.
I do not myself have an EPA license, but I do have an aquaintance who does, who is willing to assist my efforts. I am really stuck on this, and would REALLY appreciate assistance designing a system which can do this.
Thank you,
Ryan.