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Effects of electric field on micro-scale flame properties of biobutanol fuel

View Article: PubMed Central - PubMed

ABSTRACT

With the increasing need of smaller power sources for satellites, energy systems and engine equipment, microcombustion pose a potential as alternative power source to conventional batteries. As the substitute fuel source for gasoline, biobutanol shows more promising characteristics than ethanol. In this study, the diffusion microflame of liquid biobutanol under electric field have been examined through in-lab experiment and numerical simulation. It is found that traditional gas jet diffusion flame theory shows significant inconsistency with the experimental results of micro scale flame in electric field. The results suggest that with the increase of electric field intensity, the quenching flow rate decrease first and increase after it reach its minimum, while the flame height and highest flame temperature increase first and drop after its peak value. In addition, it was also observed that the flame height and highest temperature for smaller tube can reach its maximum faster. Therefore, the interaction between microscale effect and electric field plays a significant role on understanding the microcombustion of liquid fuel. Therefore, FLUENT simulation was adopted to understand and measure the impacts of microflame characteristic parameters. The final numerical results are consistent with the experimental data and show a high reliability.

No MeSH data available.


Relationship between highest temperature and flow rate.(a) tube 1; (b) tube 2.
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f9: Relationship between highest temperature and flow rate.(a) tube 1; (b) tube 2.

Mentions: Although the highest temperature of the flame is difficult to be directly measured by experimental tools, it can be shown in the flame temperature contour chart of numerical simulation as observed in Figs 4 and 6. The interrelationship between highest temperature and flow rate is presented in Fig. 9. The highest temperature increases almost linearly with the increase of liquid biobutanol flow rate. More fuel combustion can release more heat, which will make the temperature of ceramic tube go up to overcome capillary force and improve the evaporation rate of biobutanol, the burning will become more sufficient and result in higher the flame temperature. Besides that, electric field and flow rate have a different impact on the highest temperature in different inner diameter tube. The highest temperature for tube1 with 4000 V electric field is higher than that without electric field. For tube 2, if flow rate is beyond 1.4 ml/h, the highest temperature with 4000 V electric field is also higher than that without electric field; while the highest temperature with 4000 V electric field below flow rate of 1.4 ml/h, the higher temperature is lower than that without electric field. The main reason is that the ion wind of electric field can drag a large amount of air into combustion zone to degrade the temperature of flame when the density of gaseous biobutanol under the condition of lower flow rate is too lower. Through comparing the flame temperature properties of two tubes, it can be found that the fuel in smaller tube can completely burn, so that ion wind of electric field will destroy this combustion balance and degrade the flame temperature. However, the ion wind of electric field will improve the combustion efficiency, because of incomplete combustion for larger tube.


Effects of electric field on micro-scale flame properties of biobutanol fuel
Relationship between highest temperature and flow rate.(a) tube 1; (b) tube 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016967&req=5

f9: Relationship between highest temperature and flow rate.(a) tube 1; (b) tube 2.
Mentions: Although the highest temperature of the flame is difficult to be directly measured by experimental tools, it can be shown in the flame temperature contour chart of numerical simulation as observed in Figs 4 and 6. The interrelationship between highest temperature and flow rate is presented in Fig. 9. The highest temperature increases almost linearly with the increase of liquid biobutanol flow rate. More fuel combustion can release more heat, which will make the temperature of ceramic tube go up to overcome capillary force and improve the evaporation rate of biobutanol, the burning will become more sufficient and result in higher the flame temperature. Besides that, electric field and flow rate have a different impact on the highest temperature in different inner diameter tube. The highest temperature for tube1 with 4000 V electric field is higher than that without electric field. For tube 2, if flow rate is beyond 1.4 ml/h, the highest temperature with 4000 V electric field is also higher than that without electric field; while the highest temperature with 4000 V electric field below flow rate of 1.4 ml/h, the higher temperature is lower than that without electric field. The main reason is that the ion wind of electric field can drag a large amount of air into combustion zone to degrade the temperature of flame when the density of gaseous biobutanol under the condition of lower flow rate is too lower. Through comparing the flame temperature properties of two tubes, it can be found that the fuel in smaller tube can completely burn, so that ion wind of electric field will destroy this combustion balance and degrade the flame temperature. However, the ion wind of electric field will improve the combustion efficiency, because of incomplete combustion for larger tube.

View Article: PubMed Central - PubMed

ABSTRACT

With the increasing need of smaller power sources for satellites, energy systems and engine equipment, microcombustion pose a potential as alternative power source to conventional batteries. As the substitute fuel source for gasoline, biobutanol shows more promising characteristics than ethanol. In this study, the diffusion microflame of liquid biobutanol under electric field have been examined through in-lab experiment and numerical simulation. It is found that traditional gas jet diffusion flame theory shows significant inconsistency with the experimental results of micro scale flame in electric field. The results suggest that with the increase of electric field intensity, the quenching flow rate decrease first and increase after it reach its minimum, while the flame height and highest flame temperature increase first and drop after its peak value. In addition, it was also observed that the flame height and highest temperature for smaller tube can reach its maximum faster. Therefore, the interaction between microscale effect and electric field plays a significant role on understanding the microcombustion of liquid fuel. Therefore, FLUENT simulation was adopted to understand and measure the impacts of microflame characteristic parameters. The final numerical results are consistent with the experimental data and show a high reliability.

No MeSH data available.