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Experimental investigations on a CO2-BASED transcritical power cycle (CTPC) for waste heat recovery of diesel engine
Lingfeng Shi, Gequn Shu, Hua Tian, Liwen Chang, Guangdai Huang, Tianyu Chen
Session: Session 1A: CO2 Power System
Session starts: Wednesday 13 September, 10:30
Presentation starts: 11:10
Room: Building 27 - Lecture room 01

Lingfeng Shi (Tianjin University)
Gequn Shu (Tianjin University)
Hua Tian (Tianjin University)
Liwen Chang (Tianjin University)
Guangdai Huang (Tianjin University)
Tianyu Chen (Tianjin University)

CO2-based transcritical Power Cycle (CTPC) could be used for engine waste heat recovery as the safety and environment-friendly characteristic of fluid, which also matches high temperature of engine exhaust gas and satisfies miniaturization demand of recovery systems. In this study, a simplified version of a CTPC system was constructed as the bottoming system and experimentally investigated to recover waste heat from exhaust gas of a heavy-duty diesel engine. The CTPC hardware was unrecuperated and the turbine was replaced with an expansion valve. By monitoring key parameters of the CTPC system and DE system, good system stability and satisfying thermal states of working fluids were observed. Investigation was based on constant operating condition of engine at speed of 1300rpm (1300ES) and 1100rpm (1100ES), constant pump condition at speed of 70rpm (70PS) and 80rpm (80PS). The CTPC system performance as a function of pressure ratio was one of the main focus points. Results indicated that the change of heat absorption and efficiency of gas heater have a clear decreasing trend with an increasing pressure ratio, mainly due the decreased mass flow rate. Compared with 1100ES, 1300ES means more heat input and more net power output, and also higher thermal efficiency at high pressure ratio range (>1.4). The advantage is feeble at the low pressure ratio range (<1.4). Up to 2.05 kW net output power was expected to be obtained at 1300ES and 80ES, and 0.043 thermal efficiency was expected at 1300ES and 70PS.