scholarly journals Digital Temperature Tracking in Porous Media Burners

2012 ◽  
Vol 45 (3) ◽  
pp. 90-93
Author(s):  
R. Salinas ◽  
U. Raff ◽  
L. A. Henríquez-Vargas
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Digital Image ◽  
Digital Image Analysis ◽  
Operating Conditions ◽  
Solid Matrix ◽  
Temperature Tracking ◽  
Temperature Position ◽  
Combustion Properties ◽  
Efficient Combustion

Combustion in porous media burners presents considerable advantages over free flame burners due to several outstanding features inter alia clean and highly efficient combustion properties allowing a considerable amount of feedback energy from the flame area to preheat the mixture of fuel and air resulting in a considerable reduction of unavoidable pollutant formations appearing e.g. as the emission of CO and NOX. In addition, porous media burners are manufactured in highly compact small sizes suitable to industrial and household heating characteristic applications. Heat transfer between solid and gas depends mainly on the porous thermophysical properties of the component known as the solid matrix. These systems are characterized by the formation of a combustion flame pulse or wave which can travel inside the burner, depending on the operating conditions at velocities of about 0.1 mm/s. In this paper, a new temperature tracking scheme is proposed based on digital image processing to determine the position and the velocity of the thermal profile. Results showed reduced errors in the estimation of the peak temperature position using digital image analysis compared to conventional thermocouple-based measurements techniques.

Analytical and Experimental Study of Combustion and Heat Transfer in Submerged Flame Metal Fiber Burners/Heaters

2003 ◽  
Vol 125 (1) ◽  
pp. 118-125 ◽  
Author(s):  
S. A. Leonardi ◽  
R. Viskanta ◽  
J. P. Gore
Keyword(s):  
Heat Transfer ◽  
Solid Phase ◽  
Convection Heat Transfer ◽  
Single Layer ◽  
Operating Conditions ◽  
Solid Matrix ◽  
Discrete Ordinates ◽  
Metal Fiber ◽  
Burner Surface ◽  
Exhaust Temperature

A theoretical model has been developed to predict the thermal performance of inert, direct-fired, woven-metal fiber-matrix porous radiant burner. The local chemical heat release was modeled by a detailed mechanism, and convection heat transfer between the gas and the solid phases in the burner was described by an empirical heat transfer coefficient. The solid matrix was modeled as a gray medium, and the discrete ordinates method was used to solve the radiative transfer equation to calculate the local radiation source/sink in the energy equation for the solid phase. The fully coupled nature of the calculations without external specification of flame location represents a key advance over past efforts towards modeling of porous radiant burners, because for a given mass flow rate the actual heat loss from the flame determines its position and is not a free parameter. The calculated results for the burner surface temperature, the gas exhaust temperature and the radiation efficiency for a single layer Fecralloy burner were compared with experimental data from this laboratory and reasonable agreement was obtained for a range of operating conditions.

Heat Transfer Modeling of a High-Temperature Porous-Medium Filled Solar Thermochemical Reactor for Hydrogen and Synthesis Gas Production

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Ruming Pan ◽  
Bachirou Guene Lougou ◽  
Yong Shuai ◽  
Guohua Zhang ◽  
Hao Zhang
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Porous Media ◽  
High Temperature ◽  
Temperature Distribution ◽  
Synthesis Gas ◽  
Gas Production ◽  
Operating Conditions ◽  
Heat Transfer Modeling ◽  
Solar Thermochemical

In this paper, heat transfer modeling of a high-temperature porous-medium filled solar thermochemical reactor for hydrogen and synthesis gas production is investigated. The numerical simulation is performed using a three-dimensional (3D) numerical model and surface-to-surface radiation model coupled to Rosseland approximation for radiation heat transfer. The effects of operating conditions and the porous structural parameters on the reactor thermal performance were investigated significantly. It was found that large axial temperature gradient and high-temperature distribution throughout the reactor were strongly dependent on the operating conditions. The inlet gas temperature has remarkable effects on the temperature distribution. The thermal performance of porous-medium filled solar thermochemical reactor could be improved by preheating the inlet gas up to 393.15 K. Moreover, a correlation was established between the protective gas inlet velocity and the porosity of porous media. The temperature difference decreased with the increase in the porosity of the inner cavity of the reactor. In contrast to the front and back parts of the inner cavity of the reactor, higher temperature distribution could be obtained in the porous region by increasing the average cell diameters of porous media.

Magnetic resonance, digital image analysis, and permeability of porous media

1987 ◽  
Vol 51 (15) ◽  
pp. 1146-1148 ◽  
Author(s):  
Christian Straley ◽  
Abigail Matteson ◽  
Sechao Feng ◽  
Lawrence M. Schwartz ◽  
William E. Kenyon ◽  
...  
Keyword(s):  
Porous Media ◽  
Image Analysis ◽  
Magnetic Resonance ◽  
Digital Image ◽  
Digital Image Analysis

Analysis of Transient Three-Dimensional Natural Convection in Porous Media

1981 ◽  
Vol 103 (2) ◽  
pp. 242-248 ◽  
Author(s):  
Y. T. Chan ◽  
S. Banerjee
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Natural Convection ◽  
Thermophysical Properties ◽  
Fluid Phase ◽  
Spherical Particles ◽  
Solid Matrix ◽  
Time Step ◽  
Nusselt Numbers ◽  
Convection In Porous Media

Transient multidimensional natural convection in porous media has been studied using a numerical method based on the simplified marker and cell technique with local cancellation of low order, diffusional truncation errors. The conservation equations and boundary conditions were phrased in terms of the primitive variables, velocity and temperature. Differences in temperature between the fluid and the solid matrix are considered. Heat transfer between the solid and liquid phases was modelled by representing the porous medium as an assemblage of spherical particles, and solving the conduction problem within the spheres at every time step. Nusselt numbers at walls were calculated from the temperature and velocity profiles. Numerical results for heat transfer through fluid saturated porous media heated from below are in good agreement with published experiments. Consideration of heat transfer between the solid and fluid phase leads to Nusselt numbers that vary with the thermophysical properties of the solid material, even when the Rayleigh number and fluid thermophysical properties are kept constant. This is also observed in experiments. The calculations also show convective instabilities of the right period at high Rayleigh numbers.

Transient Analysis for a Double-Pass Solar Collector With and Without Porous Media

Solar Energy ◽  
2002 ◽  
Author(s):  
Elradi A. Musa ◽  
K. Sopian ◽  
Shahrir Abdullah
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Solar Collector ◽  
Industrial Process ◽  
Operating Conditions ◽  
Experimental Results ◽  
Outlet Temperature ◽  
Double Pass ◽  
Agricultural Produce ◽  
Friction Factors

The double-pass solar collector with porous media in the lower channel provides a higher outlet temperature compared to the conventional single-pass collector. Therefore, the thermal efficiency of the solar collector is increasing. The solar collector can be used for a wide variety of applications such as solar industrial process heat and solar drying of agricultural produce. A theoretical model has been developed for the double-pass solar collector. An experimental setup has been designed and constructed. Comparisons of the theoretical and the experimental results have been conducted. Such comparisons include the outlet temperatures and thermal efficiencies of the solar collector for various design and operating conditions. Close agreement has been obtained between the theoretical and experimental results. In addition, heat transfer and pressure drop relationships have been developed for air following through the porous media. The porous media has been arranged with difference porosities to increase heat transfer, area density and the total heat transfer rate. The heat transfer coefficient and friction factors are strong function of porosity.

Heat Transfer and Pressure Drop Correlations for Double-Pass Solar Collector With and Without Porous Media

2002 ◽  
Author(s):  
K. Sopian ◽  
Adam M. Elradi ◽  
Shahrir Abdullah ◽  
K. V. Wong
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Operating Conditions ◽  
Transient Heat Transfer ◽  
Double Pass ◽  
The Heat Transfer Coefficient

Correlations of transient heat transfer and pressure drop have been developed for air flowing through the porous media, which packed a double-pass solar air heater. Various porous media are arranged in different porosities to increase heat transfer, area density and the total heat transfer rate. Transient heat transfer experiments indicate that both the heat transfer coefficient and the friction factor are strong functions of porosity. The heat transfer coefficient and the friction factor are also strong functions of the geometrical parameters of the porous media. A test collector was developed and tested indoors by varying the design features and operating conditions using a halogen-lamp simulator as a radiation source. This type of collector can be used for drying and heat applications such as solar industrial processes, space heating and solar drying of agricultural products.

Digital Image Analysis of the Larynx

2000 ◽  
Vol 10 (2) ◽  
pp. 7-9
Author(s):  
Yaser Natour ◽  
Christine Sapienza ◽  
Mark Schmalz ◽  
Savita Collins
Keyword(s):  
Image Analysis ◽  
Digital Image ◽  
Digital Image Analysis
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