Energy efficiency and air distribution characteristics of jet ventilation in crossflow for long-narrow mining working faces

Long-term exposure to extreme heat in mines jeopardizes worker health and reduces productivity. This study introduces and evaluates the air distribution of jet ventilation in crossflow (JVIC) mode for localized mine cooling. Experimental and numerical simulations reveal two distinct wake structures: single wakes for wall-attached and impinging jets, and double wakes for deflected jets, influenced by counter-rotating vortex pair (CVP) structures, which accelerate cooling loss. Key parameters—jet-to-crossflow velocity ratio (R), vent equivalent diameter-to-roadway height ratio (C), and jet-to-crossflow Reynolds number ratio—govern flow modes and CVP dynamics, while jet-to-crossflow temperature ratio (T) primarily affects cooling distribution within the jet, confirming a velocity-dominated flow field. A quantitative model was developed to characterize JVIC air distribution, detailing boundaries, diffusion widths, and velocity and temperature trajectories. The model demonstrates that wall-attached and highly deflected jets enable more stable cooling with slower diffusion and reduced energy loss. Under conditions of R = 1 and C = 3, the jet achieves the highest local cooling effectiveness (εt), maintaining a cooling efficiency of 29.9% at x/dm = 3, demonstrating JVIC's ability to maintain effective cooling over extended distances. A practical evaluation shows that the novel JVIC mode achieves a cooling load of 184.9 kW, reducing energy consumption by 86.7% compared to traditional full-air cooling (1387 kW). These findings highlight JVIC's potential for efficient, targeted mine ventilation, advancing cooling efficiency and energy conservation.