Experimental investigation on the effects of Miller cycle coupled with asynchronous intake valves on the performance of a high compression ratio GDI engine. (15th January 2023)

• Record Type: Journal Article
• Authors: Qiao, Junhao; Liu, Jingping; Zhang, Quanchang; Liang, Jichao; Wang, Rumin; Zhao, Yangguang; Shen, Dazi
• Is Part Of: Fuel. Volume 332(2023)Part 1
• Publication Date: 2023-01-15
• Subjects: ICE internal combustion engine -- GDI Gasoline direct ignition -- VVA Variable valve actuation -- CR compression ratio -- OC Otto cycle -- MC Miller cycle -- EIVC Early intake valve closing -- LIVC Late intake valve closing -- AIVMC asynchronous intake valve Miller cycle -- ECR effective compression ratio -- CAD crank angle degree -- TDC top dead center -- ATDC after top dead center -- BTDC before top dead center -- BTE brake thermal efficiency -- ITE indicated thermal efficiency -- ITE_hp high-pressure indicating thermal efficiency -- NOx nitric oxide metabolite -- NO nitric oxide -- PEX-PIN the difference between inlet and exhaust pressure -- HC hydrocarbon -- SI spark ignition -- Fig figure -- ECU electronic control unit -- HRR heat release rate -- IMEP indicated mean effective pressure -- IMEP_COV coefficient of variation of IMEP -- BMEP brake mean effective pressure -- PMEP pumping mean effective pressure -- FMEP friction mean effective pressure -- Eq equation -- PCP peak cylinder pressure -- MPRR maximum pressure rising rate -- EER effective expansion ratio -- SOC start of combustion -- EOC end of combustion -- CA50 50% combustion position -- CA1090 10–90% combustion duration; GDI turbocharged engine -- Asynchronous intake valve -- Miller cycle -- High compression ratio -- Effective expansion ratio; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2022.126088
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: The research of asynchronous intake valve Miller cycle with 14.5 geometric compression ratio. A comparative experimental investigation of Otto cycle and AIVMC was conducted. Vortex flow is generated by asynchronous intake valve on the basis of tumble engine. Compared with the baseline engine, the maximum improvement of BSFC is 7.7% with AIVMC. Abstract: In this study, a series of comparative experiments were conducted on a gasoline direct ignition (GDI) turbocharged engine to investigate the effects of asynchronous intake valve Miller cycle (AIVMC) on the performance, combustion and emissions characteristics. The results show that using the asynchronous valve closing in the test engine can not only realize the Miller cycle, but also flexibly control the load, effectively reduce pump loss and improve fuel economy compared to the late intake valve closing. The minimum brake specific fuel consumption (BSFC) of the test engine equipped with and without the AIVMC are 235.59 g/kwh and 255.2 g/kwh at the condition of 2600 rpm and brake mean effective pressure (BMEP) 8 bar, which obtains a reduction of 7.7% compared to the baseline engine. In addition, the corresponding brake thermal efficiency (BTE) of test engine used the AIVMC is 35.6%, which is improved 8.2%. Besides, under the same geometric compression ratio, using the AIVMC in the test engine effectively improves the antiknock performance, keeps the 50% combustion location (CA50) closer to top dead center, shortens combustion duration, and expands the load range of low fuel consumption. As for emission performance, compared with baseline engine, though the application of AIVMC has lower mean in-cylinder temperature, the NOx emissions increases at low and medium loads but decreases at high load while HC emissions increases.