D. Boewe Hydro Aluminum Thermodynamic analysis indicates that the transcritical CO2 cycle has lower COP than R134a. Better thermophysical properties are the advantage for R744. We are exploring the causes and further potential of the system. We research properties and experimentally study the effects of potassium format based coolants on performance of commercial refrigeration systems. Single phase secondary refrigerants are simpler to use but due to sensible heat, require significant flows.
Ice slurry has potential in flow reduction and thermal storage.
We study experimental flow and heat characteristics of propylene glycol slurry. The existance of droplets in the superheated vapor at the evaporator exit is an indication of refrigerant maldistribution. Analysis of frequency content related to liquid mass fraction indicates that it could be a reliable signal for control of ganged MEMS valves used for refrigerant throttling. The transcritical CO2 cycle is very promising at low temperature lifts, particularly for heat pumps. We are comparing the performance of several in-house developed systems to the baseline R410A system, which is the best conventional system available.