{"title":"Experimental study on the spray characteristics of high-pressure liquid ammonia under different ambient conditions","authors":"","doi":"10.1016/j.joei.2024.101771","DOIUrl":null,"url":null,"abstract":"<div><p>As a promising carbon-free fuel, ammonia is expected to be widely applied in internal combustion engines. However, the physical properties of ammonia are quite different from those of conventional fuels, which leads to different spray characteristics. In this paper, the ammonia spray under injection pressure as high as 80 MPa was visualized by the diffused back-illumination imaging method, and the liquid ammonia spray characteristics under different ambient pressures and ambient temperatures were analyzed. The liquid spray penetration length, cone angle and tip velocity calculated from the spray images provide a reference database for numerical simulation. The results show that the development characteristics of liquid ammonia spray are significantly different under flare flash boiling, transitional flash boiling and non-flash boiling conditions. Flash boiling (especially flare flash boiling) inhibits the initial liquid spray penetration. The spray tip velocity increases first and then gradually decreases under flash boiling conditions. Ammonia spray has obvious radial expansion at the initial stage of flare flash boiling and the spray contour under flare flash boiling conditions is noticeably distorted, forming an obvious dilute region. With the increase of ambient pressure, the intensity of flash boiling reduces, the dilute region gradually disappears, and the distortion of the spray contour gradually weakens. Under non-flash boiling conditions, ammonia spray presents a dense and regular shape; there is no spray acceleration but a sharp decrease in spray tip velocity at the initial stage, and then the spray penetrates forward at a similar velocity. The spray penetration velocity decreases significantly with the increase of ambient pressure. The increase in ambient temperature accelerates the vaporization of ammonia spray. The liquid spray penetration length decreases and maintains with only slight fluctuations during the injection process as the ambient temperature increases from 300 K to 600 K because the vaporization rate and penetration velocity reach a balance.</p></div>","PeriodicalId":17287,"journal":{"name":"Journal of The Energy Institute","volume":null,"pages":null},"PeriodicalIF":5.6000,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of The Energy Institute","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1743967124002496","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
引用次数: 0
Abstract
As a promising carbon-free fuel, ammonia is expected to be widely applied in internal combustion engines. However, the physical properties of ammonia are quite different from those of conventional fuels, which leads to different spray characteristics. In this paper, the ammonia spray under injection pressure as high as 80 MPa was visualized by the diffused back-illumination imaging method, and the liquid ammonia spray characteristics under different ambient pressures and ambient temperatures were analyzed. The liquid spray penetration length, cone angle and tip velocity calculated from the spray images provide a reference database for numerical simulation. The results show that the development characteristics of liquid ammonia spray are significantly different under flare flash boiling, transitional flash boiling and non-flash boiling conditions. Flash boiling (especially flare flash boiling) inhibits the initial liquid spray penetration. The spray tip velocity increases first and then gradually decreases under flash boiling conditions. Ammonia spray has obvious radial expansion at the initial stage of flare flash boiling and the spray contour under flare flash boiling conditions is noticeably distorted, forming an obvious dilute region. With the increase of ambient pressure, the intensity of flash boiling reduces, the dilute region gradually disappears, and the distortion of the spray contour gradually weakens. Under non-flash boiling conditions, ammonia spray presents a dense and regular shape; there is no spray acceleration but a sharp decrease in spray tip velocity at the initial stage, and then the spray penetrates forward at a similar velocity. The spray penetration velocity decreases significantly with the increase of ambient pressure. The increase in ambient temperature accelerates the vaporization of ammonia spray. The liquid spray penetration length decreases and maintains with only slight fluctuations during the injection process as the ambient temperature increases from 300 K to 600 K because the vaporization rate and penetration velocity reach a balance.
作为一种前景广阔的无碳燃料,氨有望在内燃机中得到广泛应用。然而,氨的物理性质与传统燃料有很大不同,这导致了不同的喷雾特性。本文采用扩散背照式成像方法对喷射压力高达 80 MPa 的氨气喷雾进行了观察,并分析了不同环境压力和环境温度下的液氨喷雾特性。根据喷雾图像计算出的液态喷雾穿透长度、锥角和尖端速度为数值模拟提供了参考数据库。结果表明,在耀斑闪沸、过渡闪沸和非闪沸条件下,液氨喷雾的发展特征有显著差异。闪沸(尤其是耀斑闪沸)抑制了初始液态喷雾的渗透。在闪蒸沸腾条件下,喷头速度先增大后逐渐减小。氨水喷雾在闪蒸沸腾初期有明显的径向膨胀,闪蒸沸腾条件下的喷雾轮廓明显扭曲,形成明显的稀释区。随着环境压力的增加,闪沸强度降低,稀释区逐渐消失,喷雾轮廓的扭曲逐渐减弱。在非闪蒸沸腾条件下,氨水喷雾呈现密集而规则的形状;在初始阶段没有喷雾加速,但喷雾尖端速度急剧下降,然后喷雾以相似的速度向前穿透。随着环境压力的增加,喷雾穿透速度明显下降。环境温度的升高加速了氨喷雾的汽化。当环境温度从 300 K 升至 600 K 时,液体喷雾的穿透长度减小,并在喷射过程中保持轻微波动,这是因为汽化速度和穿透速度达到了平衡。
期刊介绍:
The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include:
Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies
Emissions and environmental pollution control; safety and hazards;
Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS;
Petroleum engineering and fuel quality, including storage and transport
Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling
Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems
Energy storage
The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.