Numerical Simulation Of Transient Response Characteristics In Methane Steam Reforming Using Concentrated Solar Irradiation As Heat Source

As we all know,the traditional energy has lots of problems,such as supply shortages,non-renewable,and environmental pollution.Faced with this,the development of all kinds of new energy resources which have the characteristics of sustainable, efficient and renewable have become the research ho tspot, solar thermochemical has become one of the key points for its innovative and efficient. Due to low yield(such as hydrogen) and high cost, the promotion of traditional solar thermochemical transformation is blocked. Compared with other types of reactors(such as tubular reactor). Attribute to the advantages of light quality, large body surface area and high conversion efficiency, the solar thermochemical transformation based on porous media become the focus of research in recent years. The study of this technology not only has important theoretical value, but also has wide prospect of engineering application. For all the above reasons, in this paper, numerical analysis of transient response characteristics in hydrogen production via methane steam reforming in porous media solar thermochemical reactor using concentrated solar irradiation as heat source has been taken.Aiming at porous media solar thermochemical reactor coated with catalytic coating, based on the mass, momentum, energy and irradiative tran sfer equations coupled with thermochemical reaction mechanism, and using the coupling method of local thermal non-equilibrium(LTNE) model and radiant interchange, in this paper, the model transient reaction which aiming at studying the response characteristics in hydrogen production via methane steam reforming in porous media solar thermochemical reactor using concentrated solar irradiation as heat source is established. For some certain basis of the hydrogen production, before the study of the transient reaction of hydrogen production via methane steam reforming, the analysis of heat transfer process in porous media has been taken, in which the point is to study the influence of temperature field transient response characteristics due to all kinds of critical factors. On the premise of mastering the temperature field transient response characteristics in the porous media, the study of thermochemical reaction transient response characteristics under typical condition. At last, in the process of thermochemical reaction, there are three main factors that have significant influence on temperature field and thermochemical reaction transient response characteristics, which are boundary conditions, physical property of porous media, and boundary radiant heat loss. Adopting the method of controlling variable, the affect that three main factors on production efficiency in the process of the transient response.The results showed that, analyzed from the influence that main factors to temperature field transient response characteristics, boundary conditions and physical properties of the porous media have significant influence on transient temperature field. The steady temperature of each point in the porous media reactor and outlet fluid temperature rise with the increase of relative content of methane on the inlet surface. Within the scope of 0.66 to 0.93 of the porosity, the outlet fluid temperature goes up with the decrease of the porosity, and the relative yields of hydrogen goes up. For example, when the porosity reduces from 0.9 to 0.7, the outlet fluid temperature goes up about 60 K, and the relative yield of hydrogen increases by about 8%. The hydrogen production on the outlet surface goes up with the increase of thermal conductivity of solid phase, such as when the coefficient of thermal conductivity increases by 20%, the hydrogen production goes up about 10%. The inlet velocity of mixed fluid goes down, the relative yield of hydrogen increases. Such as when the velocity decreases 0.025m/s, the relative production o f hydrogen increases about 6%.Without considering of the boundary radiant heat loss, the hydrogen production on the outlet surface is higher, but on the actual work environment, due to the high temperature of entrance wall, radiant heat loss has great influence on transient temperature and product field, so the proper way is try to reduce its influence under the premise of considering the radiation heat loss.