Compact CO2 Heat Pump for Shipboard Refrigeration

Shipboard refrigeration systems are critical for the storage of perishable foods, requiring precise temperature control. The Navy currently employs modular refrigeration units (MRU) mounted in the refrigerated storeroom. Existing MRUs utilize R-404A and R-407A refrigerants, with capacities of 0.75 and 1.5 tons of refrigeration (rTons). However, production and import of hydrofluorocarbons (HFC) are in the process of being phased out. New heat pump designs are needed that meet requirements while eliminating reliance on refrigerants that are increasingly difficult to stock, complicating supply chains.ÝTo address this need, Creare proposes an ultra-compact CO2 heat pump powered by a miniature, high speed turbo?compressor.ÝThis technology builds upon decades of experience building similar maintenance?free high?speed compressors and expanders for challenging DoD and NASA applications, as well as recent progress through the DoD to adapt the technology for shipboard environmental cooling and heating.ÝIn PhaseÝI we will prove the feasibility of this approach by developingÝa preliminary turbo?compressor design and associated analyses. Once the compressor design is complete, we will specify the remaining components that make up a compact MRU for shipboard installation including evaporator and condenser heat exchangers. We will also build a test facility to de-risk one of the major challenges with this miniature compressor design: thermal management of the high power-density compressor motor. This is accomplished using direct-contact liquid cooling of the motor assembly. During the Option phase, we will assemble a breadboard CO2 heat pump with a commercial compressor and heat exchangers and assess the performance of the compressor and baseline performance of the other system components. This breadboard heat pump will later be used in Phase II to demonstrate Creareís turbo-compressor.