First 2 Stage Cascade System

[Maine Engineer]

First off want to thank Mythical for getting me interested in phase change vapor cooling. Currently working on assembling parts and equipment for my first 2 stage cascade system. Initially I was looking at just trying to use a refrigeration evaporator to run both stages to achieve target temperatures, but with no real end result. I've since refocused to using the evaporator to bring the ambient latent load down on the first stage and using the 2nd stage for the direct vapor phase cooling. Since I'm building my first system at my shop I have access to 1 & 3 phase 240V power and high current draw. Pictures will be posted after info. Onto the build components:

Refrigerants:

R507 - 1st stage
R744 & R600 Blend for 2nd Stage

R507 is a suitable first stage refrigerant with the ability to rapidly decrease the ambient temperature in the overall space I intend to cool with a Larkin LCE635BEB ECM 3500BTUH, 700 CFM, Electric Defrost evaporator unit.

R744 was chosen through consulting with Mythical due to its great latent heat potential compared to Ammonia refrigerant. A blend has to be made to inhibit the CO2 from becoming dry ice in the system. Also with using R744, since it's a newer refrigerant, parts are harder to come by and more precautions and safeties must be brought into the circuits. I am in the process of working with Emerson Climate on their R744 training so I don't turn my shop to toothpicks.


Compressors:

Initially I sent out quotes to United Refrigeration, FW. Webb and Bell Simons Co. for Emerson Climates' new ZR/ZC series of CO2 compressors for the 2nd stage build, but upon receiving the prices I laughed and said I'll wait. $4500 per compressor at wholesale cost. Nope no thanks for now.

1st stage will just be a simple 507 rated air cooled refrigeration condenser set up. Nothing fancy here. Tecumsah AKA2430ZAADC $837.16


Electronics:

Saftronics PC102001-9 3 Phase VFD Controller paired with an A.O. Smith 3 Phase 1HP motor
Dixell XR60CX-5N1F1-UR Refrigeration Controller
Emerson Climate E2 RX Controller
ICM Variable Speed Controller
Sporlan Solenoid Coils
Honeywell T775 Series Temperature Controller with temperature sensors for 1 stage BK10K2RPFEP10BB and for 2nd stage BK1K1RPFEP10BB

Refrigeration Components:

Rolls of 1mm Cap Tube; 1/4, 3/8 and 1/2 Soft Drawn ACR for majority of piping
HXR25 Suction Line Heat Exchangers
Temprite 603 Oil Separators
20-30 Plate Oil Cooler 1600PSI Heat Exchanger for Cascade piping due to CO2's potential to go critical if the gas gets above 87F
Various 15-30 Plate Heat Exchangers on 507 side
Various Refrigeration Ball Valves

R744 (CO2) Side:
Custom designed and built stainless steel or Type K copper Plated heat exchangers, evaporator and condenser coils.
Specially engineered pressure relief valves that must vent outside to prevent injury or death
New Regulator Manifolds
Specifically designed CO2 Refrigeration Manifold with 1500PSI Hoses
In general everything on the CO2 side is either stainless or K type Copper


Lots & Lots of Research and Development. Thankfully I own my own HVAC company and I work for another with a full service sheet metal shop, which means I can get just about anything built for this project.