Analysis of Thermophysical Properties of Daqing RP-3 Aviation Kerosene

针对广泛应用于超燃冲压发动机的吸热碳氢燃料,简要介绍了用于模拟燃料热物理特性的替代燃料方法和广义对应状态法则.以大庆RP-3航空煤油为例,选择了一个由49%（摩尔比）正十烷,44%1,3,5-三甲基环己烷以及7%正丙基苯组成的替代煤油用来模拟RP-3航空煤油进行热物理特性研究,并采用广义对应状态法则对替代煤油热力学和输运特性进行了数值研究.在此基础上,提出了预测超临界态流体通过音速喷管流量的新方法并得到了实验验证.

Catalytic Cracking and Heat Sink Capacity of Aviation Kerosene Under Supercritical Conditions

Catalytic cracking of China no. 3 aviation kerosene using a zeolite catalyst was investigated under supercritical conditions. A three-stage heating/cracking system was specially designed to be capable of heating 0.8 kg kerosene to a temperature of 1050 K and pressure of 7.0 MPa with maximum mass flow rate of 80 g/s. Sonic nozzles of different diameters were used to calibrate and monitor the mass flow rate of the cracked fuel mixture. With proper experiment arrangements, the mass flow rate per unit throat area of the cracked fuel mixture was found to well correlate with the extent of fuel conversion. The gaseous products obtained from fuel cracking under different conditions were also analyzed using gas chromatography. Composition analysis showed that the average molecular weight of the resulting gaseous products and the fuel mass conversion percentage were a strong function of the fuel temperature and were only slightly affected by the fuel pressure. The fuel conversion was also shown to depend on the fuel residence time in the reactor, as expected. Furthermore, the heat sink levels due to sensible heating and endothermic cracking were determined and compared at varying test conditions. It was found that at a fuel temperature of similar to 1050 K, the total heat sink reached similar to 3.4 MJ/kg, in which chemical heat sink accounted for similar to 1.5 MJ/kg.

Thermal cracking of aviation kerosene for scramjet applications

Thermal cracking of China No.3 aviation kerosene was studied experimentally and analytically under supercritical conditions relevant to regenerative cooling system for Mach-6 scramjet applications. A two-stage heated tube system with cracked products collection/analysis was used and it can achieve a fuel temperature range of 700-1100 K, a pressure range of 3.5-4.5 MPa and a residence time of approximately 0.5-1.3 s. Compositions of the cracked gaseous products and mass flow rate of the kerosene flow at varied temperatures and pressures were obtained experimentally. A one-step lumped model was developed with the cracked mixtures grouped into three categories: unreacted kerosene, gaseous products and residuals including liquid products and carbon deposits. Based on the model, fuel conversion on the mass basis, the reaction rate and the residence time were estimated as functions of temperature. Meanwhile, a sonic nozzle was used for the control of the mass flow rate of the cracked kerosene, and correlation of the mass flow rate gives a good agreement with the measurements.

Heat Transfer of Aviation Kerosene at Supercritical Conditions

The heat transfer characteristics of China no. 3 kerosene were investigated experimentally and analytically under conditions relevant to a regenerative cooling system for scramjet applications. A test facility developed for the present study can handle kerosene in a temperature range of 300-1000 K, a pressure range of 2.6-5 MPa, and a mass How rate range of 10-100 g/s. In addition, the test section was uniquely designed such that both the wall temperature and the bulk fuel temperature were measured at the same location along the flowpath. The measured temperature distributions were then used to analytically deduce the local heat transfer characteristics. A 10-component kerosene surrogate was proposed and employed to calculate the fuel thermodynamic and transport properties that were required in the heat transfer analysis. Results revealed drastic changes in the fuel flow properties and heat transfer characteristics when kerosene approached its critical state. Convective heat transfer enhancement was also found as kerosene became supercritical. The heat transfer correlation in the relatively low-fuel-temperature region yielded a similar result to other commonly used jet fuels, such as JP-7 and JP-8, at compressed liquid states. In the high-fuel-temperature region, near and beyond the critical temperature, heat transfer enhancement was observed; hence, the associated correlation showed a more significant Reynolds number dependency.

Kinetic study of hydrolysis of xylan and agricultural wastes with hot liquid water

We investigated the kinetics of hot liquid water (HLW) hydrolysis over a 60-min period using a self-designed setup. The reaction was performed within the range 160-220 °C, under reaction conditions of 4.0 MPa, a 1:20 solid:liquid ratio (g/mL), at 500 rpm stirring speed. Xylan was chosen as a model compound for hemicelluloses, and two kinds of agricultural wastes-rice straw and palm shell-were used as typical feedstocks representative of herbaceous and woody biomasses, respectively. The hydrolysis reactions for the three kinds of materials followed a first-order sequential kinetic model, and the hydrolysis activation energies were 65.58 kJ/mol for xylan, 68.76 kJ/mol for rice straw, and 95.19 kJ/mol for palm shell. The activation energies of sugar degradation were 147.21 kJ/mol for xylan, 47.08 kJ/mol for rice straw and 79.74 kJ/mol for palm shell. These differences may be due to differences in the composition and construction of the three kinds of materials. In order to reduce the decomposition of sugars, the hydrolysis time of biomasses such as rice straw and palm shell should be strictly controlled.