High Efficiency R744 Centrifugal Chiller

Most medium and large commercial and industrial facilities use packaged water chillers of 50 ton capacity and higher for air conditioning and refrigeration. The current refrigerants used are HFC-134a or HCFC-123, which need to be replaced by an environmentally benign alternative that offers zero ozone-depletion and negligible global warming. Among all candidate refrigerants, R744 (carbon dioxide) has been found to be the best, taking into account all requirements, including non-flammability and non-toxicity. However, due to R744¿s inherent inefficiency, a direct application to the conventional chiller cycle requires high power consumption, .2 kW/ton, which is far higher than the ASHRAE recommended value of 0.576 kW/ton. This project will develop a high-efficiency R744 chiller cycle. In Phase I, the feasibility of the innovative R744 chiller concept will be confirmed through a thermodynamic analysis. In Phase II, a prototype will be fabricated and tested to confirm the high-efficiency target. In Phase III, a prototype package of 150 ton capacity will be built and field tested. Commercial Applications and other Benefits as described by the awardee: The high-efficiency R744 chiller initially will be marketed by targeting the replacement of existing reciprocating and screw chillers in commercial and industrial sectors ranging from 50 to 400 tons of cooling capacity.