Decheng Li¹, Yan Zhang², Dongdong Ma², Haozhe Geng¹, Yu Wu^1,2,*

Energy Engineering, Vol.120, No.11, pp. 2503-2516, 2023, DOI:10.32604/ee.2023.041803

Abstract The fracturing process of sandstone is inherently complex due to its loose internal structure and deformation adaptability. Liquid nitrogen pre-injection has emerged as a promising approach to damage reservoir rocks, effectively reducing fracture pressure and establishing intricate fracture networks, thus offering a potential solution for reservoir reconstruction. To unravel the fundamental mechanisms governing sandstone fracturing behaviors following liquid nitrogen pre-injection, sandstone fracturing experiments were conducted under varying durations of liquid nitrogen injection, rock temperature, and in-situ stress conditions. The experiments showcased the evolution of injection pressure and fracture characteristics under different testing conditions, complemented by electron microscope analysis to elucidate… More >

Binbin Yang^1,*, Leilei Liu¹, Yan Zhang¹, Jingyu Gong¹, Fan Zhang², Tiezhu Zhang¹

Energy Engineering, Vol.120, No.10, pp. 2233-2250, 2023, DOI:10.32604/ee.2023.028898

Abstract Gasoline compression ignition (GCI) has been considered as a promising combustion concept to yield ultra-low NO_X and soot emissions while maintaining high thermal efficiency. However, how to improve the low-load performance becomes an urgent issue to be solved. In this paper, a GCI engine model was built to investigate the effects of internal EGR (i-EGR) and pre-injection on in-cylinder temperature, spatial concentration of mixture and OH radical, combustion and emission characteristics, and the control strategy for improving the combustion performance was further explored. The results showed an obvious expansion of the zone with an equivalence ratio between 0.8~1.2 is realized… More >