(378u) Organic Rankine Cycle Waste Heat Recovery System to Cool the Data Center

The problem / opportunity is to improve the process of removing waste heat from IT equipment in data centers through use of a heat recovery process. The information and communication technology industry consumes 2% of globe's energy. Nearly all the electrical input power results in waste heat. Demand for increased compute speed and capacity while minimizing operation latency has driven processor heat density beyond what can be cooled with air. Processors operate successfully at temperatures up to 95°C. Direct liquid cooling (DLC) can capture the waste heat at 85°C making it available for heat recovery between at 75°C and 80°C. Smaller data centers (aka Edge) are less than 500 kW IT load. These facilities utilize traditional cooling techniques that consume energy at an average rate of 40% of the IT load. Nearly 3,000,000 sites exist globally.

ORC has proven effective in heat recovery applications with low temperature differentials. Average ambient temperature of 14C provides 60C to 65C driving force for the ORC system. At 50% of ideal efficiency and allowing for heat rejection power, the ORC can deliver 7% of the input waste heat as high quality energy. The primary technology gap in ORC is the expander. Various research projects have found scroll machines to be effective expanders. The focus of this research effort is to design and test scroll expanders producing a design that may be commercialized.

The HVACR industry has developed efficient long life scroll compressors. The basic scroll device is reversible. Identifying and developing the design changes to convert commercial scroll compressor requiring electrical power input to a scroll expander producing electrical power output is the research required to enable this process improvement. In simple terms, an ORC heat recovery system is an HVACR vapor compression refrigeration system operating in reverse. The components of the two systems are comparable and expected to be similar in cost. The process improvement results in reduction of 40% of IT load to remove the waste heat to a 7% net supply of electrical energy. Total energy usage will be reduced by 34%.