Most medium and large commercial and industrial facilities use packaged water chillers ranging from 50 ton capacity and up for air conditioning and refrigeration. Their current refrigerants are chemicals which will soon be phased out and replaced by environmentally benign alternative refrigerants of zero ozone-depletion and negligible global warming. Among all candidate refrigerants, Carbon dioxide has been found to be the best considering all requisite conditions including non-flammability and non-toxicity. Because of its inherent inefficiency arising from a transcritical cycle with low critical temperature, a direct application to the conventional chiller cycle requires power consumption of 1.2 kW/ton at the rating condition. As an innovative breakthrough, a high efficiency carbon dioxide chiller will be developed. By reducing overall pressure ratio, the cycle efficiency is dramatically increased to provide the power consumption as low as 0.5 kW/ton at 150 tons of cooling capacity. The proposed innovative carbon dioxide cycle is easily scalable to chiller sizes other than 150 tons. In Phase I, the feasibility of the innovative carbon dioxide chiller concept was successfully confirmed through a thermodynamic analysis of the cycle. A preliminary analysis of all the components also showed the feasibility of anticipated performance. Mechanical integrity of all key components was verified through a preliminary mechanical design. An overall system size and volume was estimated, and any conflicts with commercial needs were checked. In Phase II, the novel design technology will be established through component tests. The demonstration of efficiency gain using the new technology installed in an existing commercial chiller will be made, which will create a near-term retrofit business of improving current chiller efficiency by simply adding the new technology, and which will minimize any potential trial-and-errors in the carbon dioxide chiller development. A complete design of the key components of the proposed carbon dioxide water chiller will be accomplished. A working relationship with a manufacturing company, specialized in packaged water chiller business, will be established. In Phase III, a prototype chiller of 150 ton capacity will be built and field tested. Commercial Applications and Other
Benefits: Marketing of the chiller will begin by targeting the replacement of existing reciprocating and screw chillers in commercial and industrial sectors rating from 50 to 400 tons of cooling capacity with cooperation in partnership with a water chiller manufacturer. The proposed project will provide a major breakthrough for improvement in energy savings using a natural refrigerant
