Thermal characteristics of a porous radiant burner (PRB) including gas radiation effects are identified in the present study. This system operates on the basis of effective energy conversion method between flowing gas enthalpy and thermal radiation. In the PRB, the gas and solid phases are considered in non-local thermal equilibrium and combustion is modeled by considering a non-uniform heat generation zone. The porous media as a gray body, in addition to its convective heat exchange with the gas, can absorb, emit and scatter thermal radiation. In order to accurately determine the thermal characteristics of PRB, the gas radiation is also taken into account and a theoretical analysis is conducted for a two dimensional model, where convection, conduction and radiation take place simultaneously in porous medium and gas flow. Discrete ordinates method is used to obtain the distribution of radiative heat flux in the porous media and the coupled energy equations for the gas and porous medium in steady condition are solved numerically. The crucial influence of gas radiation effect on the system's performance is thoroughly explored. A comparison has been made between the present numerical results and those reported by other investigators to validate the simulation for the gas radiative effect.

In this paper, a new type of gas-to-gas heat exchanger that operates based on energy conversion between gas enthalpy and thermal radiation is developed. This system consists of one high temperature section and two recovery sections. In high temperature section, the enthalpy of hot gas flow converts to thermal radiation by porous layer in this section and the reverse direction of this process occurs in recovery sections. A theoretical analysis is conducted for the one-dimensional system where convection and radiation take place simultaneously in three porous layers. In order to obtain the thermal characteristics of this type of heat exchanger, the coupled energy equations for the gas and porous mediums based on two-flux radiation model are solved numerically using iterative method. Computational results show that this type of heat exchanger works effectively especially when the porous layers with large optical thicknesses and small scattering factors are used in the system. In order to validate the numerical results, a comparison between theory and experiment is made for a system of heat recovery and a good agreement is found.

A new kind of high power tunable radiation source, where the short electromagnetic pulse is generated by a perpendicularly magnetized plasma wake is studied. A gas jet flow is used to generate the sharp boundary plasma. Wakefield is excited by a mode locked Ti:sapphirc laser beam operating at 800 nm wavelength with the pulse width of 100 fs (FWHM) and maximum energy of 100 mJ per pulse with 10 Hz repetition rate. Different nozzles are used in order to generate different densities and gas profile. The neutral density of gas jet flow is measured with a Mach-Zehnder interferometer. Strength of the applied external dc magnetic field varies from 0 to 8 kG in the interaction region normal to the direction of laser pulse propagation. The frequency of the emitted radiation with the pulse width of 200 ps (detection limitation) is in the millimeter wave range. Radiation is polarized perpendicularly to the laser pulse propagation direction and dc magnetic field lines. Radiation propagates mainly in the forward direction. Intensity of the radiation in different plasma densities and different magnetic field strengths has been observed.

In gas detectors with UV absorbing gas mixture, the Self-Quenched Streamer (SQS) mode can be achieved following the proportional mode, which leads to appear the light column. In this study, the design, simulation and construction of three micro pattern gas-detector, THGEM, with different geometric dimensions are presented. Moreover, the ability of operation in SQS mode to determine incident rays position without using any conventional imaging system is investigated. In the presence of UV absorbing gas mixtures, the proportional mode of the gas detector operation is followed by SQS mode as soon as the visible light column appears at the ray entrance location. In the employed method, each THGEM hole as an image pixel can operate in the SQS mode with emerging a light column, independent of other holes. As a consequence, it can be used for alpha beam detection since the brightness of each hole at a certain voltage is proportional to the number of primary electrons entered the hole.

In the present research, the equilibrium data of ternary systems, carbon dioxide- toluene- naphthalene is determined by using a high-pressure apparatus. Mentioned data is measured between 298.15 K and 308.15 K and pressure at 9.6 to 75.6 bar. In each experiment, equilibrium solubilities of naphthalene in toluene decrease by increasing the pressure due to adding the carbon dioxide as the anti-solvent. Also, the obtained experimental data have correlated by the Soave-Redlich-Kwong equation of states along with Van der Waals 1 and 2 mixing rules.The adjustable parameters of mentioned models are obtained using the experimental data and reported along with average absolute relative deviation of each model. The results show that SRK equation of state with vdW2 mixing rule (AARD=11.75 %) has less deviation than SRK-vdW1 (AARD=14.41 %) and optimum operational condition for production of fine particles (over than 90%) in the GAS process has been suggested.

In this paper, the thermal characteristics of single and double flow plane solar heaters with radiating working gas were analyzed and compared by numerical analysis for the first time. The laminar mixed convection gas flow in the heaters was numerically simulated by the CFD method using the finite volume technique. The set of governing equations included the conservation of mass, momentum and energy for the convective gas flows and the conduction equation for solid parts. Besides, the radiative transfer equation was solved by the discrete ordinate method for radiant intensity computation. From numerical results, the thermal efficiency of single flow heater found very sensitive to gas optical thickness, such that gas radiation always has positive influence on the performance of system. The efficiency increase about 50% was computed for optical thicknesses more than 2 in the test cases. However, for double flow gas heater with less sensitivity to gas radiation and reciprocating trend for thermal efficiency with optical thickness, 15% increase in thermal efficiency was seen at the optimum optical thickness. Comparison between the present numerical results and those reported in literature, showed good consistency.

A novel design of solar air heater is proposed in this paper based on the simultaneous exploitation of radiating gas and also airfoil-shaped ribs. Using participating gases with high radiative characteristics concerning the usual working gas, namely air, could show a more promising improvement in thermal performance, especially while this technique is combined with extending surface area. This new concept is demonstrated by simultaneous solution of the radiative transfer equation considering both the diffuse and collimated beams coupled with momentum, energy, and continuity equations. The set of governing equations are solved using the finite element method in a steady-state condition by the COMSOL Multi-physics. The well-known  model is used in calculations of turbulent stress and heat flux in numerical simulation. Through the presented results, radiative gas proved its full potential to serve as a future working gas in solar gas heaters. Its combination with the airfoil-shaped ribs shows magnificent 88% thermal efficiency and gas outlet temperature up to 85°C in the test cases. The contributions of airfoil-shaped ribs and also the gas radiation to increase thermal performance are computed equal to 7% and 66%, respectively.