Porous media burner (PMB) is widely used in a variety of practical systems, including heat exchangers, gas propulsion, reactors, and radiant burner combustion. However, thorough evaluations of the performance of the PMB based on the usefulness of entropy generation, thermal and exergy efficiency aspects are still lacking. In this work, the concept of a double-layer micro PMB with a 23 mm cylindrical shape burner was experimentally demonstrated. The PMB was constructed based on the utilization of premixed butane-air combustion which consists of an alumina and porcelain foam. The tests were designed to cover lean to rich combustion with equivalence ratios ranging from ϕ = 0.6 to ϕ = 1.2. It was found that the maximum thermal and exergy efficiency was obtained at ϕ = 1.2 while the lowest thermal and exergy efficiency was found at ϕ = 0.8. Furthermore, the findings also indicated that the total entropy generation, energy loss, and exergy destroyed yield the lowest values at ϕ = 1.0 with 0.0048 W/K, 98.084 W, and 1.456 W, respectively. These values can be stated to be the suitable operating conditions of the PMB. The findings provided useful information on the design and operation in a double-layer PMB. 相似文献
The shifted-1 expansion techniques (SLET) has been developed to get eigenvalues of Schrödinger equation in three (30) and two dimensions (2D). SLET simply consists of 1/l as a perturbation parameter, where l= 1 -β.β is a suitable shift, l is the angular-momentum quantum number for the 3D-case, l = |m| for the 2D-case, and m is the magnetic quantum number. Unlike the shifted large-N expansion theory (SLNT), SLET seems to be applicable to a wider number of problems of significant interest in physics. 相似文献
Summary: A comprehensive model is developed to predict the relationship between the particle size distribution and molecular weights of particles in an emulsion copolymerization reactor. A full population balance equation is used for the particle size distribution and extended to the model for the molecular properties using a continuous reactor approach. The numerical prediction clearly distinguishes the characteristics of molecular properties of particles by homogeneous nucleation from those by micellar nucleation with the dependence on the particle size. Sensitivity analysis of the proposed model under a variety of conditions shows that the compartmentalized feature of the emulsion system should be considered for better prediction of molecular properties, and provides information on the manipulated variables and lumped parameters which effectively decompose the correlation of both properties. Finally, a control strategy utilizing a lumped parameters tracking method is suggested for the regulation of both the particle size distribution and molecular properties.
Time evolution of number‐averaged molecular weights in the element under base conditions. 相似文献
In this study, heat removal from a surface, which is located into the reciprocating flow in a vertical annular liquid column,
is investigated experimentally. The experiments are carried out for four different oscillation frequencies and three heat
fluxes while the amplitude remains constant for all cases. Instantaneous and time-averaged surface and bulk temperature variations
are presented. The cycle-averaged values are considered in the calculation of heat transfer using the experimental measurements.
Heat removal from the cold surface due to the oscillating liquid column is determined in terms of Nusselt number. Based on
the experimental data, an empirical equation is obtained for the cycle averaged Nusselt number as a function of kinetic Reynolds
number. 相似文献
In this work, the magnetohydrodynamics (MHD) natural convection heat transfer problem inside a porous medium filled with inclined rectangular enclosures is investigated numerically. The boundary conditions selected on the enclosure are two adiabatic and two isothermal walls. The governing equations, continuity, and Forchheimer extension of the Darcy law and energy are transformed into dimensionless forms by using a set of suitable variables, and then solved by using a finite difference scheme. The governing parameters are the magnetic influence number, the Darcy Rayleigh number, the inclination angle, and the aspect ratio of the enclosure. It is found that the magnetic influence number and the inclination angle have pronounced effects on the fluid flow and heat transfer in porous media-filled enclosures. 相似文献
A procedure for preconcentration of Mn(Ⅱ), Fe(Ⅱ), Co(H), Cu(Ⅱ), Cd(Ⅱ), Zn(Ⅱ), Pb(Ⅱ) and Ni(Ⅱ) based on retention of their complexes with 8-hydroxyquinoline (HQ) on Amberlite XAD-2000 resin in a column was proposed for the analysis of environmental samples by flame AAS. Various parameters such as pH, eluent type, volume, concentration, flow rate and volume of sample solution, and matrix interference effect on the retention of the metal ions were investigated. The optimum pHs for the retention of metal complexes in question were about 6 except for Mn^2+ for whose value is 8. The loading capacity of the adsorbent for these metals and their recoveries from the resin under the optimum conditions were in the range 6.82-9.26 mg·g^-1 and 95%-101%, respectively. The enrichment factor was calculated as 100 and the limit of detection was in the range 0.3-2.2 μg·L^-1 (n=20, blank+ 3s). The proposed enrichment method was applied to tap water, stream water and vegetable samples. The validation of the procedure was carried out by analysis of certified reference material and standard addition. The analytes were determined with a relative standard deviation lower than 6% in all samples. 相似文献
A new polymeric resin with glucose sulfonamide functions has been prepared for the extraction of boric acid. This poly (styryl sulfonamide) based resin has been demonstrated to be an efficient sorbent for the removal of boron. The resin had a boron loading capacity of 2.365 mmol.g−1 and showed reasonably rapid sorption ability. Splitting of sorbed boron can be achieved by simple acid leaching (2M H2SO4). 相似文献