Characteristics and movement of upper spray droplets in exhaust air flow heat recovery device

doi:10.16265/j.cnki.issn1003-3033.2022.03.022

Abstract

Abstract:

In order to effectively improve the efficiency of heat and wet energy extraction from mine exhaust, effects of nozzle atomization pressure and airflow speed on up-spray droplet group's characteristic particle size and dispersed phase fraction were tested by using Malvern laser particle size analyzer in the mine exhaust heat and humidity extraction device with upper spray type, and data of 21 engineering conditions were tested and collected. Then, influence of nozzle operation parameters and exhaust airflow mechanical parameters on dispersed phase fraction of droplet groups was determined by using critical Weber number and ligament diameter calculation formula. Finally, a single droplet's migration correlation with droplet group characteristic particle size was derived by introducing dispersed phase fraction. The results show that the primary breakage type of liquid film is linear instability breakage with long wavelength. When nozzles' atomizing pressure increases, particle size of liquid droplets decreases while fraction of dispersed phase increases. The resistance coefficient increases with the introduction of dispersed phase fraction, which has a quasi-lubrication effect on droplet migration.

Key words: exhaust airflow, droplet group, dispersed phase fraction, resistance coefficient, extreme distance of migration

FAN Siyu, CHEN Shiqiang, HE Weiguo, TIAN Feng, LIU Chunyu, LIU Gang. Characteristics and movement of upper spray droplets in exhaust air flow heat recovery device[J]. China Safety Science Journal, 2022, 32(3): 158-166.

Figures/Tables 11

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喷雾压力/MPa	评价指标	液滴粒径/μm
喷雾压力/MPa	评价指标	30%	35%	40%	45%	50%	55%	60%
0.20	D₁₀	199	222	208	212	189	251	241
	D₅₀	431	444	443	452	440	444	460
	D₉₀	797	826	806	801	831	891	801
0.25	D₁₀	244	200	240	234	229	235	231
	D₅₀	467	448	421	423	444	450	478
	D₉₀	771	760	778	769	764	770	803
0.30	D₁₀	156	169	145	150	145	140	166
	D₅₀	490	446	402	421	420	426	400
	D₉₀	760	773	765	752	770	778	800

风量/%		30	35	40	45	50	55	60
0.20 MPa	U_a	3.94	4.50	5.04	5.64	6.23	7.08	7.93
	U_l	14.00
	U_s0	10.06	9.50	8.96	8.36	7.77	6.92	6.07
0.25 MPa	U_a	3.94	4.50	5.04	5.64	6.23	7.08	7.93
	U_l	15.65
	U_s0	11.71	11.15	10.61	10.01	9.42	8.57	7.72
0.30 MPa	U_a	3.94	4.50	5.04	5.64	6.23	7.08	7.93
	U_l	17.15
	U_s0	13.21	12.65	12.11	11.51	10.92	10.07	9.22