Theoretical analysis and comparison on supercritical CO2 based combined cycles for waste heat recovery of engine. (1st September 2020)

• Record Type: Journal Article
• Authors: Pan, Mingzhang; Zhu, Yan; Bian, Xingyan; Liang, Youcai; Lu, Fulu; Ban, Zhibo
• Is Part Of: Energy conversion and management. Volume 219(2020)
• Publication Date: 2020-09-01
• Subjects: Waste heat recovery -- Organic Rankine cycle -- Supercritical CO2 Brayton cycle -- Dual-fuel engine; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2020.113049
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: Four different CO2 Brayton-based dual-loop cycles are proposed. Waste heat of dual-fuel engine is used as heat source. Comparative thermodynamic performance analysis is conducted. Zeotropic mixtures are adopted in the ORC. The system with supercritical CO2 recompression Brayton cycle/organic Rankine cycle presents the best performance. Abstract: Supercritical carbon dioxide cascade waste heat recovery has proven to be a promising alternative for energy conversion applications. In this paper, four different CO2 Brayton-based dual-loop cycles are integrated to the dual-fuel engine respectively to recover the engine waste heat, including regenerative supercritical CO2 Brayton cycle/organic Rankine cycle (RSCBC/ORC), regenerative supercritical CO2 Brayton cycle/supercritical CO2 Brayton cycle (RSCBC/SCBC), supercritical CO2 recompression Brayton cycle/organic Rankine cycle (SCRBC/ORC), and supercritical CO2 recompression Brayton cycle/supercritical CO2 Brayton cycle (SCRBC/SCBC). Comprehensive parametric analysis and comparison were carried out. When the engine was operated at 1100 rpm and cycle fuel injection quantity of 14.1 mg, the SCRBC/ORC combined system presents the best performance when cyclohexane is used as the working fluid for the ORC, followed by the RSCBC/ORC, RSCBC/SCBC, and SCRBC/SCBC. The energy efficiency of the whole system is increased by 7.03% with the SCRBC/ORC, compared with the condition that engine without waste heat recovery.