Experimental study on the rock-breaking characteristics of abrasive liquid nitrogen jet for hot dry rock

Abrasive liquid nitrogen (LN2) jet is regarded as one of the most efficient methods to break hard rock, such as hot dry rock (HDR), due to its unite low-temperature property. In this study, a novel experimental setup is designed to achieve abrasive LN2 jet under high-pressure condition. The impingement experiments with abrasive water jet is also conducted to characterize the rock-breaking features under cryogenic condition. The influences of six important parameters on rock-breaking are investigated in detail. The results indicate that compared with abrasive water jet, abrasive LN2 jet can create a larger and more irregular cavity with the lower threshold pressure. The parametric study shows that nozzle pressure drop mainly affects the cavity depth, while the nozzle diameter affects the cavity-opening diameter noticeably. The particle diameter and rock temperature both have a great influence on cavity-opening diameter and cavity depth. This study can provide theoretical support for abrasive-LN2-jet application.