Heat transfer analysis of catalytically supported thermal combustion reactors with a heat insulating material and high exterior heat losses
Description
Heat transfer analysis is made for catalytically supported thermal combustion reactors with a heat insulating material and high exterior heat losses. The wall thermal conductivity and exterior convective heat loss coefficient are taken as independent parameters to understand how important thermal management is. The temperature, species molar fraction, and reaction rate data with high exterior heat losses are obtained for catalytically supported thermal combustion reactors. In conventional thermal combustion, fuel and air in inflammable proportions are contacted with an ignition source to ignite the mixture which will then continue to burn. Catalytic combustion heretofore has been generally regarded as having limited practicality in providing a source of power as a consequence of the need to employ impractically large amounts of catalyst so as to make a system unduly large and cumbersome. It is possible to achieve essentially adiabatic combustion in the presence of a catalyst at a reaction rate many times greater than the mass transfer limited rate. Catalytically supported thermal combustion surmounts the mass transfer limitation. The catalytically supported thermal combustion reactor comprises a concentric annular channel, wherein the concentric annular channel further comprises an inner annular channel and an outer annular channel. A platinum catalyst is deposited only upon the interior surface of the inner channel, and the wall of the outer channel is chemically inert and catalytically inactive. The concentrically arranged annular channel is 5.0 millimeters in inner channel length, 5.6 millimeters in outer channel length, 0.8 millimeters in innermost diameter, 2.6 millimeters in outermost diameter, 0.1 millimeters in catalyst layer thickness, and 0.2 millimeters in wall thickness. The spacing between the inner channel and the outer channel is 0.4 millimeters and remains constant. The reactor can have any dimension unless restricted by design requirements. All the walls have the same thickness. One of the potential problems associated with the reactor continues to be combustion stability. The maximum Reynolds number is less than 360 at the flow inlet and 960 when the velocity of the flow of the fluid is highest in the channels. Detailed chemistry is included in the model. Detailed chemical mechanisms are incorporated into the reacting flow for the reactor. The homogeneous combustion is modeled with the detailed chemical mechanism for methane oxidation in CHEMKIN format. Detailed heterogeneous chemistry in SURFACE-CHEMKIN format is included in the model. Contributor: Junjie Chen, E-mail address: koncjj@gmail.com, ORCID: 0000-0002-5022-6863, Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China
Files
Steps to reproduce
To facilitate computational modeling of transport phenomena and chemical kinetics in the flowing system of complex chemical reactions involving gas-phase and surface species, steady-state analyses are performed and computational fluid dynamics is used. ANSYS FLUENT is applied to the problem involving surface chemistry.