Yoshio Yoshizawa

A study of the available energy of a combustion system with energy recirculation.

The available energy of a combustion system with energy recirculation between products and reactants is discussed extensively, and it is shown that there exists a theoretical maximum of the available energy of the combustion system corresponding to the adiabatic limit flame temperature of the combustible mixture. Since this limit temperature is an inherent temperature of a combustible mixture based on the thermochemical properties of the constituents, the maximum available energy is also an inherent value of the combustible mixture. It is also shown in this paper that a combustion system with energy recirculation has the potential to realize a higher thermodynamic efficiency from the point of view of generating power even when the allowable maximum temperature in the combustion system is lower than the theoretical temperature of combustion of the reactant mixture of the system.

A study on a high-performance radiant heater with a porous medium energy converter.

This study aims to develop a high-performance radiant heater which would be able to convert almost all energy released by combustion into thermal radiation. A compact radiant heater was produced, which was an application of the effective energy conversion method from flowing gas enthalpy to thermal radiation emitted from the porous medium of an appropriate optical thickness placed in a duct of high-temperature gas. It consists of a porous medium energy converter and a quartz window. It is also equipped with a convective heat exchanger between the burnt and unburnt gases. The thermal radiation emitted from the porous medium energy converter is taken out in the opposite direction to the burnt gas flow. The temperature profiles in the heater were examined and the energy balance of the heater has been elucidated. The results shows that 80 to 90% of the energy released by combustion is converted into thermal radiation.

An application of a porous medium radiant heat exchanger to a reactor for methane steam reforming. (The concept and the analysis of basic operation characteristics).

A new concept of a reactor for methane steam reforming has been proposed, which is an application of a high-performance radiant heat exchanger composed of a couple of porous media energy converters. One of the porous media also works as the support for the catalyst on which the endothermic reaction takes place. Therefore, the heat is transferred directly to the place where it is consumed as the heat of reaction. A numerical model is developed describing a one-dimensional model of the reactor, and the basic operation characteristics, such as the profiles of temperatures and concentrations in the reactor, the local and the total energy balances and overall yield, have been discussed and clarified extensively for a wide range of operating conditions of the reactor.

Combustion of gaseous fuels in porous media (An experimental study on temperature profiles in porous media and an analysis on radiation field.

空げき率のきわめて大きな多孔性固体の特異な伝熱特性に起因する顕熱・ふく射エネルギ変換効果,ふく射遮へい効果,伝熱促進効果,燃焼侭進効果を応用した高性能加熱装置の開発を目的として,多孔性固体と燃焼の相互作用および多孔性固体内に形成される温度場およびふく射場を実験および数値解析により詳細に明らかにした.その結果,多孔性固体内に高温で強いふく射場の一様な空間を形成することが可能であることが実証された.