Systematic bifurcation analysis of a planar diffusion flame model with radiative heat losses

2012 ◽  
Author(s):  
Michail E. Kavousanakis ◽  
Lucia Russo ◽  
Francesco Saverio Marra ◽  
Constantinos Siettos
Keyword(s):  
Bifurcation Analysis ◽  
Diffusion Flame ◽  
Radiative Heat ◽  
Heat Losses

Effect of Corrugated Cover Directional Transmittance on the Thermal Performance of a Solar Collector

1981 ◽  
Vol 103 (2) ◽  
pp. 144-152
Author(s):  
T. F. Smith ◽  
S. Chaidar
Keyword(s):  
Solar Energy ◽  
Periodic Function ◽  
Thermal Performance ◽  
Solar Collector ◽  
Radiative Heat ◽  
Structural Strength ◽  
Heat Losses ◽  
Light Weight ◽  
Fiberglass Composite ◽  
Reduced Costs

The benefits of light weight, structural strength, and reduced costs without significant reduction of transmission of solar energy of a corrugated fiberglass composite cover promise wide utilization of this cover in solar collectors to suppress convective and radiative heat losses from the absorber panel. In order to evaluate the thermal performance of a collector with a corrugated cover, the directional transmittance of the cover must be available. A study was undertaken to develop a model for the directional transmittance of a corrugated cover as represented by a sinusoidal periodic function. As an application of this model, hourly and daily thermal efficiencies of a solar collector with a corrugated cover are presented.

Theoretical Assessment of Convective and Radiative Heat Losses in a One-Dimensional Multiregion Premixed Flame With Counter-Flow Design Crossing Through Biofuel Particles

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Mehdi Bidabadi ◽  
Saman Hosseinzadeh ◽  
Sadegh Sadeghi ◽  
Mostafa Setareh
Keyword(s):  
Temperature Profile ◽  
Radiative Heat ◽  
Flame Structure ◽  
Flame Temperature ◽  
Heat Losses ◽  
Flame Velocity ◽  
Mass Fractions ◽  
Interface Matching ◽  
Energy Balances ◽  
Stagnation Plane

Due to perspective of biomass usage as a viable source of energy, this paper suggests a potential theoretical approach for studying multiregion nonadiabatic premixed flames with counterflow design crossing through the mixture of air (oxidizer) and lycopodium particles (biofuel). In this research, convective and radiative heat losses are analytically described. Due to the properties of lycopodium, roles of drying and vaporization are included so that the flame structure is created from preheating, drying, vaporization, reaction, and postflame regions. To follow temperature profile and mass fraction of the biofuel in solid and gaseous phases, dimensionalized and nondimensionalized forms of mass and energy balances are expressed. To ensure the continuity and calculate the positions of drying, vaporization, and flame fronts, interface matching conditions are derived employing matlab and mathematica software. For validation purpose, results for temperature profile is compared with those provided in a previous research study and an appropriate is observed under the same conditions. Finally, changes in flame velocity, flame temperature, solid and gaseous fuel mass fractions, and particle size with position measured from the position of stagnation plane, strain rate, and heat transfer coefficient in the presence/absence of losses are evaluated.

Radiative heat losses from gas flames

1974 ◽  
Vol 7 (4) ◽  
pp. 492-495
Author(s):  
A. I. Rozlovskii ◽  
V. G. Khasanov ◽  
R. Kh. Gimatdinov
Keyword(s):  
Radiative Heat ◽  
Heat Losses

Modelling Turbulent Combustion in a Non-Adiabatic CO/H2 Flame Using Reaction Progress Variables

1996 ◽  
Author(s):  
Jim B. W. Kok ◽  
Jurgen J. J. Louis
Keyword(s):  
Gas Turbine ◽  
Heat Loss ◽  
Diffusion Flame ◽  
Turbulent Combustion ◽  
Heat Losses ◽  
Intermediate Species ◽  
Reaction Progress ◽  
Fuel Concentration ◽  
Fuel Mixing ◽  
Loss Effect

A model is presented for the turbulent combustion of CO/H2-air mixtures at gas turbine conditions. The model takes account of heat losses. The conversion of CO to CO2 and of H2 to H2O, as well as the non-equilibrium intermediate species concentrations are determined by two reaction progress variables and two other scalar variables. The initially available fuel concentration is expressed by a fuel mixing variable. The heat loss effect on the enthalpy is described by a scaled enthalpy variable. The modelled turbulent source terms in the transport equations for the scalar variables are discussed. Three cases of a turbulent CO/H2 diffusion flame with heat loss and chemical super-equilibrium of intermediate species are presented.

scholarly journals GENERAL MODEL OF RADIATIVE AND CONVECTIVE HEAT TRANSFER IN BUILDINGS: PART II: CONVECTIVE AND RADIATIVE HEAT LOSSES

2019 ◽  
Vol 59 (3) ◽  
pp. 224-237
Author(s):  
Tomáš Ficker
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Numerical Methods ◽  
Radiative Heat ◽  
Convective Transport ◽  
Heat Losses ◽  
Computational Method ◽  
Weak Points ◽  
Serial Publication ◽  
Heat Transfers

The present paper represents the second part of the serial publication, which deals with convective and radiative heat transfers in buildings. The algebraic computational method for combined convective-radiative heat transport in buildings has been proposed. The convective transport of heat has been formulated by means of the correlation functions of the Nusselt number. The radiative heat transfer has been specified by using the radiosity method explained in the first part of the serial publication. The system of transcendent equations has been formed to couple the convective and radiative heat transports. The transcendent system has been solved iteratively, which has facilitated to obtain the optimized surface temperatures as well as the optimized values of the coefficients of heat transfer. On the basis of these optimized values, a more precise overall heat loss has been computed and compared with the results obtained from the thermal standard. The strong and weak points of the both used numerical methods have been discussed.

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