Waste heat driven absorption/vapor-compression cascade refrigeration system for megawatt scale, high-flux, low-temperature cooling

A novel cascaded absorption/vapor-compression cycle with a high temperature lift for a naval ship application was conceptualized and analyzed. A single-effect LiBr–H2O absorption cycle and a subcritical CO2 vapor-compression cycle were coupled together to provide low-temperature refrigerant (−40 °C) for high heat flux electronics applications, medium-temperature refrigerant (5 °C) for space conditioning and other low heat flux applications, and as an auxiliary benefit, provide medium-temperature heat rejection (∼48 °C) for water heating applications. A thermodynamic model was developed to analyze the performance of the cascaded system, and parametric analyses were conducted to estimate the performance of the system over a range of operating conditions. The performance of the cascaded system was also compared with an equivalent two-stage vapor-compression cycle. This cycle was found to exhibit very high COPs over a wide range of operating conditions and when compared to an equivalent vapor-compression system, was found to avoid up to 31% electricity demand.

►A novel cascaded absorption/vapor-compression cycle with a high temperature lift for a naval ship application was conceptualized and analyzed. ►A single-effect LiBr–H2O absorption cycle and a subcritical CO2 vapor-compression cycle were coupled to provide low temperature refrigerant (−40 °C) for high heat flux electronics applications, medium temperature refrigerant (5 °C) for space conditioning. ►The cycle was modeled for a naval ship application where the absorption cycle was powered by the exhaust heat from the onboard gas turbine power plants. ►The system COPs on total input energy basis, and total electric input basis were estimated to be 0.594 and 5.685, respectively. ►With 200 MW of waste heat input, 82 MW of cooling at 5 °C, and 51 MW of cooling at −40 °C are delivered, with an investment of only 23 MW of compressor power.