超临界压力RP-3壁面结焦对流阻的影响

实验研究了长时间加热条件下航空煤油RP-3在微细不锈钢管内流动过程中结焦对流动及换热的影响规律。实验中系统压力保持为5 MPa,燃油质量流量为3 g/s。在燃油溶解氧达到饱和的条件下,实验段进出口油温分别为130℃和450℃。实验从开始到终止持续36 h。实验结果表明,随着时间的增长,管内的结焦量不断增加。由于壁面结焦现象对管内流动和换热产生严重的影响,管内各段换热在实验前期迅速恶化逐渐趋于稳定,管内流阻随着实验时间的增加持续增长。管内流动阻力随着时间的增长呈现出"快速增长→平稳增长→急速增长"的过程。另外,基于实验结果,提出了一种影响系数作为判断结焦对换热器单管影响的工程模型。 

Effects of RP-3' s wall coke deposition on flow resistance under supercritical pressure

The effect of the jet fuel RP-3 coking deposition in stainless micro-tube on flow resistance and heat transfer characteristics under long heating condition is analyzed based on experimental results. In the experiment, fuel flowing through miniature tube was heated from 130℃ to 450℃ under the pressure 5 MPa when dissolved oxygen in fuel saturated. The whole experiment lasted 36 h with the mass flow rate maintained at 3 g/s. The experimental results show that with the growth of time, coking amount in the tube increases along time. The results also show that the effect of coke deposition on flow resistance and heat transfer is significant. As more and more coke particles adhere, the heat transfer resistance increases rapidly in the early stage of the test and gradually stabilizes, while the flow resistance along the miniature tube increases as the experiment continues. As time grows, the flow resistance in the tube presents a "rapid growth to steady growth, then to exponential growth" process. Besides, based on the test results, an influence coefficient used as an engineering model to value the impact of the coke deposition on single tube of the heat exchanger is proposed.