جستجوی مقالات مرتبط با کلیدواژه "chemiluminescence" در نشریات گروه "مکانیک"

The Chemiluminescence method is considered as one of the most widely spread optical methods which is used for identifying combustion systems. In this study, the CH* and OH* Chemiluminescence signals were measured with the use of PMT detector and other optical equipments for a bunsen burner. Also the effect of equivalence ratio and flow rate on these signals have been investigated. The results show that with increasing flow rate, CH* and OH* signals increase linearly. By changing the equivalence ratio, Chemiluminescence signals were maximized near stoichiometric condition. Therefore, these two types signals can be considered as an the heat release rate indicator and can be used to find the optimal working conditions for any desired burner. It was also shown that OH*/CH* is independent of mass flow rate and only affected by the equivalence ratio.Then, the calibration relationship between equivalene ratio and OH*/CH* signal has been extracted for a certain range of equivalence ratio, which is also true in other combustion condition. Finally, the application of this method has been evaluated to identify the dynamics of combustion systems. The results show that the premixed flames have a dominant peak frequency due to the Kelvin-Helmholtz vortices. In premixed flames, the peak frequency is decreased by increasing the equivalence ratio and the corresponding amplitude increases. Also, with increasing flow rate, the peak frequency is linearly increased and its amplitude decreases linearly. This work shows the potential of using the Chemiluminescence method as an effective tool in the field of experimental identification of combustion systems, as well as for controlling and manitoring the lean of fuel combustion chamber and identifying dynamic combustion phenomena.

In this study, a fully premixed cylindrical surface flame burner is investigated in laboratory research. The burner was analyzed in heating capacities 11.74-17.14 kW and its equivalence ratio 0.4-1.6. The results are including two sections of spectroscopy and flame image analysis. In the chemiluminescence section, the maximum heat release from the perforated cylindrical burner is obtained by examining the intensity of hydroxyl radiation in the equivalence ratio of 0.8. In the second part of chemiluminescence, the equivalence ratio is estimated by using the intensity ratio and curve fitting from natural flame radiation. The color and state of the flame changed from the equivalence ratio of 1.6 to 0.44, respectively, from green to yellow and red flame, blue and lift-off flame, and eventually blow-off. The satisfactory operation that is stable blue flame without lift-off and flashback is observed in the range of 0.7-0.85. This process was performed for six thermal capacities, and its results were collected in a chart called the functional burner diagram. A satisfactory operation can be selected by a functional diagram in different burner powers.

In the present research, combustion species where investigated in perforated natural gas burner based on Flame Emission Spectroscopy (FES). Experimental investigation is performed on a new burner test rig which is one of most popular burners used in condensation boilers through a spectrometer-fiber optic to get the flame emission of a perforated burner. Combustion species H2O*, OH*, CH* ,C2* and CO2* are detected from their chemiluminescence The emission of CO2* which has the main role in heat release rate of burner was investigated for different equivalence ratios (Φ) and burner powers of 11-16 kW showing an intensity peak in the range of Φ between 0.78 to 0.85 that corresponds to the maximum heat release rate. Emission of OH* was also investigated being the main indicator of NO regarding to its producing mechanism. Its maximum was found at the ragne of at Φ=0.78 to 0.85 for different burner powers. The similar experiment showed that OH*/CH* intensity ratio was independent of burner power as is confirmed by previous researchers. One could infer equivalence ratio from the flame emission.

In the present research, combustion species detection in methane/air flame is carried out based on Flame Emission Spectroscopy (FES). Experimental investigation is performed on a test rig equipped with measurement devices to get the flame emission of a perforated burner which is one of most popular burners used in condensation boilers. Combustion species H2O*, OH*, CH* and C2* are detected from their chemiluminescence The emission of OH* radical was investigated for different equivalence ratios (Φ) and burner powers showing an intensity peak in the range of Φ between 0.77 to 0.85 that corresponds to the maximum heat release rate. Emission of H2O* was also investigated leading to its maximum at Φ=0.82 which shows the most complete combustion equation for different burner powers. The similar experiment showed that OH*/CH* intensity ratio was independent of burner power as is confirmed by previous researchers. One could infer equivalence ratio from the flame emission. Burner surface temperature was also targeted by an infrared thermometer with the purpose of finding the maximum surface temperature of 415 to 420oC which happened at nearly Φ=0.82 for all burner powers. Finding equivalence ratio of the burner by using its natural emission and improving its efficiency by the method of investigating combustion specifications relating to heat release rate is the basis of this work.