Greenhouse culture is one of the agriculture sector's production methods that is highly dependent on energy. Therefore, if the efficiency of greenhouse heating systems is improved, it will have sound effects on the energy consumption of the greenhouse sector in the country. In this study, to determine the efficiency of fuel consumption of conventional heating systems in greenhouses, data were taken in 6 greenhouses in Alborz province. For this purpose, the thermal requirements of greenhouses were calculated. Then climate suitability graphs were drawn. For determining fuel efficiency, in addition to recording thermal images in the greenhouse, the status of exhaust gases such as CO, CO2, HC, O2, and NOx was recorded in the greenhouse. The results showed that the greenhouses in Alborz province need to heat for 6 months. The average efficiencies of the burners used in the greenhouses were 85%. The pollution of heating systems in these areas also showed that the percentage of CO and CO2 gases were 0.06 and 3.085 in greenhouses, respectively. HC and NOx pollutants were 9.1 and 13.36 ppm, respectively. Factors such as using non-standard heating systems and improper installation of heating systems were the most important factors in creating these pollutants.

Optical emission spectroscopy is known as a prevalent technique for plasma diagnostic which was applied in many experiments. The present research is important and considerable from two points of view. First, with accurate details, the spectroscopy of the plasma plume has been analyzed and it was significant since internationally the plume temperature has been less investigated in comparison with the excited electrons temperature, and also is remarkable as regards the national reports may be even not found such study. In the second view, considering in the non-transfer plasma torch design, the plasma plume temperature estimation and its characterization were substantial and necessary. These results are obtained using the Boltzmann method and exact analysis of the Fortrat curve and the selection of the P branch of the curve known as the first negative system N2+(B-X), based on the dominant Nitrogen molecules in the air. By exact selection of rotational quantum numbers, regarding maximum spectrum intensities, the macroscopic plasma plume temperature, and excited electrons temperature were estimated 2000 (0.17 eV) and 6400 (0.5 eV) Kelvin respectively. The temperature results of this thermal torch sample are compared with international authoritative reports and also with the thermodynamic approach in a similar condition and is in the minimum spectrum of temperature which was excepted. It means that, the macroscopic plume temperature is still far away from related thermal plasma near the excited electron temperature (more than 4000 K). Therefore, to design a desirable plasma torch with suitable electrodes and other parameters, and achieve the 4000 K macroscopic temperature, it is in the minimum spectrum of temperature or efficiency and these obtained results are important and necessary for the precise design of a waste-incinerator torch pursuing with this purpose in the future.

In this paper, experimental comparison between conventional burner and porous burner in domestic purposes as stove, according to Iranian National Standard No. 10325 has been carried out. This comparison between the conventional burner available in the Iranian market and its equivalent porous burner is done. First, flammability of the porous silicon carbide burner was investigated. The results showed that the flame is formed when the equivalence ratio is less than 1, so the best performance equivalence ratio was around 0.7. By changing the distance between the pot and the burner and also changing the pot diameter, it was found that for a pot with 26 cm diameter and burner distance of 1 cm, porous burner efficiency increases to 55%. The comparison between the conventional burner and optimum situation porous burner showed that at the same factors like power, distance between the pot and the burner, the pot diameter, the burner diameter, measuring tools and the same method, porous burner efficiency is 1.5 times more than conventional burner. In conventional burners CO and NOX pollutant are 8-26 and 8 times more than porous burners. Due to higher efficiency and lower emissions, conventional burners can supersede porous burners for domestic purposes.

Due to considerable height of the flaring flames, wind speed has siginificant effects on its flame shape and cause consequent damages. In this paper, the effects of wind speed on the flame shape and the temperature distribution of the flare wall are investigated using three-dimensional numerical simulation of turbulent combustion. Results show that at wind speeds higher than 5m/s, the flame lies over the flare wall causing its temperature to increase. Moreover, as the wind speed changes, the position of the maximum temperature point on the flare wall also changes, causing the material to experience fatigue failure.

Premixed combustion in a Combined Porous-Free Flame Burner (CPFFB) and a porous burner (PB) is numerically studied at a cylindrical axisymmetric combustion chamber. The cylindrical porous medium is perforated in the center line that a combination of porous burner and free flame is made. Governing equations of mass, momentum, energy and species mass fraction are solved using finite volume method. In this numerical simulation, a reduced multi-step combustion mechanism and realizable k-ε turbulence model are used. To validate the numerical results, an experimental prototype of the burner was made and has been tested. The numerical results have a good agreement with the experimental data. The results are compared for both types of the burners.The results show that the flame in CPFFB is stable in a range greater than that of PB. The results show that the CPFFB has a higher thermal power about 50% and lower NO pollutant formation about 20% rather than an equivalent PB.

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.

The combustion system used by the Hoffman furnaces for brick factories has a very low efficiency. In the current paper, the performance of the combustion system of Hoffman furnaces of Kolet Pottery Brick Co has improved, using computational fluid dynamics (CFD) by making changes to the Hoffman furnace torch, including the converging the torch head, inserting the spring in the pipe to create the swirl flow, shortening the nozzle length for the better mixing of the fuel and air, and more. The changes were simulated in each step with the FLUENT simulation software. Based on the theoretical results and simulation, optimized torch was made and a field test was carried out on it in a brick factory and the gases from their combustion were analyzed. As a result of these reforms, the combustion efficiency of the Hoffman furnaces has increased from 27% to 47 %, and consumption of fuel oil has decreased by a third. Also, the CO value of 16854 ppm in the old torch was reduced to 298 ppm in the optimized torch and the NO value ranged from 49 to 18 ppm as a result of optimizations.

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.

This research was carried out to optimize energy consumption in Isfahan Steel P-type boilers by numerical modeling of heat transfer in combustion chamber at different angles of natural gas fuel burner. Using the Ansys-Fluent combustion chamber modeling software, four natural gas burners, 187 firefighting tubes and its refractory walls were used. The results show that changing the angle of the burner is a good way to control the flame. By decreasing the angle of the burner, the heat flux on the firebox tubes the temperature and fluid velocity inside the combustion chamber increases and thus improves the boiler efficiency. However, reducing the angle of the burners results in an increase in the surface temperature of the fire pipes and can even pierce and damage the equipment. The results also showed that with constant amount of gas consumed, the ratio of radiation heat transfer to total heat transfer of firewall tubes at different angles is 90% on average. Also the agreement between numerical and experimental results including the existing boiler condition in which the burner at 30 ° angle confirms the modeling accuracy.