CN111500326B

CN111500326B - Liquid hydrocarbon fuel low-temperature stable combustion method based on Lailton-free effect

Info

Publication number: CN111500326B
Application number: CN202010342839.9A
Authority: CN
Inventors: 黄小彬; 刘洪�; 赵正创; 何淼生; 张斌
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2020-04-27
Filing date: 2020-04-27
Publication date: 2022-02-25
Anticipated expiration: 2040-04-27
Also published as: CN111500326A

Abstract

A liquid hydrocarbon fuel low-temperature stable combustion method based on no Layton effect is characterized in that the optimized proportion of a metal organic compound, nano particles and a substrate fuel is designed, and the evaporation heat transfer rate of the fuel is accelerated by utilizing the low-temperature autoxidation heat release of the metal organic compound and the heat conduction performance of the nano particles, so that the Layton effect in the low-temperature combustion process is eliminated. The invention has the advantages of high stability, low spontaneous combustion temperature, short ignition delay time, stable combustion, good stability of contact air at normal temperature and the like, and can realize the regulation and control of the high-efficiency stable combustion of the liquid hydrocarbon fuel at a wide range of temperature. Simple operation and strong practicability.

Description

Liquid hydrocarbon fuel low-temperature stable combustion method based on Lailton-free effect

Technical Field

The invention relates to a technology in the field of aviation fuels, in particular to a liquid hydrocarbon fuel low-temperature stable combustion method based on the Lailton-free effect.

Background

Compared with hydrogen fuel, liquid hydrocarbon fuel has higher volumetric energy density, has outstanding advantages in the aspects of environmental storage, safety, reliability, economy, transportation and the like, and gradually becomes the first choice of fuel for advanced aeroengines. However, under severe conditions such as low temperature, the chemical reaction activity of the liquid hydrocarbon fuel is low, the ignition delay time is long, the minimum ignition energy is large, and the fuel combustion characteristic is deteriorated, so that the advanced air-breathing engine is difficult to stably combust at low temperature. The main reason is that the fuel needs to be subjected to physical and chemical processes such as atomization, evaporation, mixing and chemical reaction from the time of injection into the combustion chamber to the time of complete combustion, the Layton effect of fuel droplets is commonly existed in the process, so that the low-temperature evaporation and combustion of the liquid hydrocarbon fuel are unstable, and particularly, the heat and mass transfer process related to the contact of the fuel droplets and the hot surface environment has great influence on reliable ignition, stable combustion and the formation of harmful pollutants, thereby restricting the development of advanced aircrafts.

The prior art can solve the problems of ignition and combustion to a certain extent through external flow field control and forced ignition, but the technologies can increase the difficulty for the combustion organization and the structural design of an engine, and simultaneously can also sacrifice the thrust performance of the engine. Therefore, the Layton effect in the whole combustion process of the liquid hydrocarbon fuel is eliminated in a chemical and physical synergistic regulation mode, and the improvement of the energy output and the heat transfer efficiency in the combustion process is an effective way for solving the problems of unstable low-temperature combustion and difficult ignition of the liquid hydrocarbon fuel.

Disclosure of Invention

The invention provides a liquid hydrocarbon fuel low-temperature stable combustion method based on the Layton effect, aiming at the problems that the existing liquid hydrocarbon fuel has limited effect in a mode of enhancing heat conduction to improve evaporation heat transfer rate and the local negative increase phenomenon of ignition delay time at a wide range of temperature, and the liquid hydrocarbon fuel low-temperature stable combustion method has the advantages of high stability, low spontaneous combustion temperature, short ignition delay time, stable combustion, good stability of contact air at normal temperature and the like, and can realize the regulation and control of high-efficiency stable combustion at the wide range of temperature of the liquid hydrocarbon fuel. Simple operation and strong practicability.

The invention is realized by the following technical scheme:

the invention relates to a liquid hydrocarbon fuel low-temperature stable combustion method based on a Leilton effect, which is characterized in that the evaporation heat transfer rate of the fuel is accelerated by designing the optimal proportion of a metal organic compound, nano particles and a substrate fuel and utilizing the low-temperature autoxidation heat release of the metal organic compound and the heat conduction performance of the nano particles, so that the Leilton effect in the low-temperature combustion process is eliminated.

The metal organic compound is preferably diethyl methoxyborane.

The nano-particles preferably adopt nano-silver, and more preferably have an average particle size of 20 nm-40 nm.

The preferable mixture ratio is as follows: 10 to 30 percent of diethyl methoxyborane, 0.1 to 0.5 percent of nano silver and the balance of base fuel.

The substrate fuel comprises: n-decane, n-hexadecane or RP-3 aviation kerosene.

The invention relates to a liquid hydrocarbon fuel without Layton effect, which comprises a liquid hydrocarbon fuel as a substrate and a mixed solution of diethyl methoxyborane and nano silver as a combustion promoter.

The liquid hydrocarbon fuel comprises the following components in percentage by weight: 10-30% of diethyl methoxyborane, 0-1% of nano-silver and 69-90% of substrate fuel.

The invention relates to a preparation method of the liquid hydrocarbon fuel, which is obtained by selecting a substrate and a combustion promoter and uniformly mixing the substrate and the combustion promoter in a physical mode under the protection of inert atmosphere.

Technical effects

The invention integrally solves the technical problem of high-efficiency activation of liquid hydrocarbon fuel without Layton effect under wide temperature range.

Compared with the prior art, the invention selects the combustion improver with synergistic effect, can efficiently and stably realize the low-temperature combustion of the liquid hydrocarbon fuel, and has simple, convenient and safe fuel preparation operation and good fuel stability.

Drawings

FIG. 1 shows the ignition temperature of pure decane and the composite hydrocarbon fuel of examples 2 and 3 on the surface of a hot plate;

FIG. 2 shows the ignition delay time of pure decane and the composite hydrocarbon fuel of examples 2 and 3 on the surface of a hot plate;

Detailed Description

Example 1

The composite hydrocarbon fuel is prepared according to the following proportion:

step one, adding 10% of diethyl methoxyborane by mass into a nitrogen-sealed fuel bottle;

and step two, adding 90% by mass of n-decane into the fuel bottle added with the diethyl methoxyborane.

And step three, uniformly mixing the fuel components in the fuel bottle in a physical mode to obtain the required composite hydrocarbon fuel. The physical mode can be but is not limited to: and (4) manually mixing.

In the embodiment, the combustion characteristic data of the composite fuel is tested by adopting a liquid drop-hot plate experimental device to illustrate the enhancement effect of the combustion improver on the low-temperature stable combustion of the liquid hydrocarbon fuel.

The minimum ignition temperature of the 10 percent diethyl methoxyborane/n-decane composite fuel in the embodiment is 145 ℃, and the ignition delay time is 674 ms; when the ignition temperature is 600 ℃, the ignition delay time can be reduced from 4027ms to 29ms of pure decane fuel.

Example 2

step one, adding 18% of diethyl methoxyborane by mass into a nitrogen-sealed fuel bottle;

and step two, adding 82% by mass of n-decane into the fuel bottle added with the diethyl methoxyborane.

Step three, uniformly mixing the fuel components in the fuel bottle in a physical mode to obtain the required composite hydrocarbon fuel; the physical mode can be but is not limited to: and (4) manually mixing.

As shown in figures 1-2, the lowest ignition surface temperature of the 18% diethyl methoxyborane/n-decane composite fuel in the embodiment is reduced from 600 ℃ of pure decane fuel to 115 ℃; the ignition delay time is in a monotonous decreasing trend along with the temperature rise, no local negative growth behavior exists, and when the ignition temperature is 600 ℃, the ignition delay time can be reduced from 4027ms of pure decane fuel to 15 ms. Therefore, compared with the combustion accelerator diethyl methoxyborane with the addition of 10%, under the condition of higher concentration, the self-oxidation heat release generated in the combustion process can effectively eliminate the Layton effect generated in the combustion process, and the low-temperature stable combustion performance of the fuel is improved.

Example 3

step one, adding nano silver powder into a nitrogen-sealed fuel bottle, wherein the mass percentage of the nano silver powder is 0.5%;

the average particle size of the nano silver powder is 20-40 nm, and the effective content is more than 99.9%;

and step two, further adding diethyl methoxyborane into the fuel bottle added with the nano silver powder, wherein the mass percentage of the diethyl methoxyborane is 18%.

And step three, adding 81.5 percent by mass of n-decane into the fuel bottle added with the nano silver powder and the diethyl methoxyborane.

Step four, uniformly mixing the fuel components in the fuel bottle in a physical mode to obtain the required composite hydrocarbon fuel;

the physical mode can be, but is not limited to: and (4) ultrasonically stirring and dispersing.

As shown in FIG. 2, the lowest ignition surface temperature of the 18 percent diethyl methoxyborane/0.5 percent nano silver/n-decane composite fuel in the embodiment is reduced from 600 ℃ of pure decane to 112 ℃; the ignition delay time shows a monotonous decreasing trend along with the temperature rise, no local negative growth behavior exists, and when the ignition temperature is 600 ℃, the ignition delay time can be reduced to 10 ms.

Compared with the comparative example 2 with 18% of combustion accelerator diethylmethoxyborane, the ignition performance of the composite fuel under the condition of wide temperature range is further improved under the condition of the existence of low-concentration nano silver, which is shown in the following concrete steps: the ignition delay time at the same temperature is reduced by 15 to 35 percent. Therefore, the effect of diethyl methoxyborane and nano silver on improving the autoxidation heat release and evaporation heat transfer rate of the liquid hydrocarbon fuel in the combustion process is obvious, the Layton effect generated in the combustion process can be effectively eliminated, and the low-temperature stable combustion performance of the fuel is improved.

In conclusion, the invention can effectively reduce the lowest ignition surface temperature and realize high-efficiency stable combustion in a wide temperature range. Specifically, the negative effects of the Laden effect on fuel evaporation and combustion stability are eliminated through the low-temperature autoxidation heat release and the interface heat transfer of the combustion improver, and the local negative growth behavior of the ignition delay time along with the temperature change disappears; the ignition delay time and the ignition temperature of the traditional liquid hydrocarbon fuel can be effectively reduced by adjusting the concentration of the combustion improver, and the ignition delay time is in a monotonous decreasing trend along with the increase of the ignition temperature; the selected combustion accelerant can be stably dispersed in the base fuel, the stability is high, the base fuel and the accelerant are simply and manually shaken up to be mixed and ultrasonically dispersed under the protection of inert atmosphere, the composite hydrocarbon fuel with the required performance can be prepared, the fuel can be stably stored under the protection of inert atmosphere, the preparation operation is simple, convenient and safe, the fuel cannot spontaneously combust under the normal temperature environment, and the stability is good. The fuel obtained by the method has important significance for enhancing low-temperature stable combustion of liquid hydrocarbon fuel, solving high-altitude flameout and low-Mach number starting of advanced air-breathing engines and the like.

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A liquid hydrocarbon fuel low-temperature stable combustion method based on no Layton effect is characterized in that a metal organic compound, nano particles and a base fuel are configured according to the mass fraction of diethyl methoxyborane of 10% -30%, the mass fraction of nano silver of 0.1% -0.5% and the balance of the base fuel, and the evaporation heat transfer rate of the fuel is accelerated by utilizing the low-temperature autoxidation heat release of the metal organic compound and the heat conduction performance of the nano particles, so that the Layton effect in the low-temperature combustion process is eliminated;

the metal organic compound adopts diethyl methoxyborane, and the nano particles adopt nano silver;

the average particle size of the nano particles is 20 nm-40 nm;

the substrate fuel comprises: n-decane, n-hexadecane or RP-3 aviation kerosene.