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Thawing of a frozen food product in a domestic microwave oven is numerically simulated using a coupled solver approach. The approach consists of a dedicated electromagnetic FDTD solver and a closely coupled UFVM multi-physics package. Two overlapping numerical meshes are defined; the food material and container were meshed for heat transfer and phase change solution, whilst the microwave oven cavity and waveguide were meshed for the microwave irradiation. The two solution domains were linked using a cross-mapping routine. This approach allowed the rotation of the food load to be captured. Power densities obtained on the structured FDTD mesh were interpolated onto the UFVM mesh for each timestep/turntable position. The UFVM solver utilised the power density data to advance the temperature and phase distribution solution. The temperature-dependant dielectric and thermo-physical properties of the food load were updated prior to revising the electromagnetic solution. Changes in thermal/electric properties associated with the phase transition were fully accounted for as well as heat losses from product to cavity. Two scenarios were investigated: a centric and eccentric placement on the turntable. Developing temperature fields predicted by the numerical solution are validated against experimentally obtained data. Presented results indicate the feasibility of fully coupled simulations of the microwave heating of a frozen product. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Cannon RD Jayasooriya UA Tilford C Anson CE Sowrey FE Rosseinsky DR Stride JA Tasset F Ressouche E White RP Ballou R 《Inorganic chemistry》2004,43(22):7061-7067
The mixed-valence double salt K(3)(MnO(4))(2) crystallizes in space group P2(1)/m with Z = 2. The manganese centers Mn1 and Mn2 constitute discrete "permanganate", [Mn(VII)O(4)](-), and "manganate", [Mn(VI)O(4)](2-), ions, respectively. There is a spin-ordering transition to an antiferromagnetic state at ca. T = 5 K. The spin-density distribution in the paramagnetic phase at T = 10 K has been determined by polarized neutron diffraction, confirming that unpaired spin is largely confined to the nominal manganate ion Mn2. Through use of both Fourier refinement and maximum entropy methods, the spin on Mn1 is estimated as 1.75 +/- 1% of one unpaired electron with an upper limit of 2.5%. 相似文献
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Dorothy S. Ginter Marshall L. Ginter Shelby G. Tilford 《Journal of Molecular Spectroscopy》1982,92(1):40-54
High-resolution absorption spectra of HI were reinvestigated in the 1475-Å (67 800 cm?1) to 1344-Å (74 400 cm?1) region. This spectral region was found to contain bands attributable to (1) V1Σ+-X1Σ+(v′-0) with v′ > 0, (2) (v′-0) transitions with v′ ≥ 0 from X1Σ+ to states associated with the (σ2π3)cπ and (σ2π3)cσ configurations, and (3) (v′-0) transitions with v′ ≥ 0 from X1Σ+ to states associated with the previously unreported configurations (σ2π3)dσ, dπ, aδ, eσ, and fσ. 相似文献
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Reflection of plane waves from the boundary of a pre-stressed compressible elastic half-space 总被引:2,自引:0,他引:2
The effect of pre-stress on the propagation and reflection ofplane waves in an incompressible isotropic elastic half-spacehas been examined recently by the authors (Ogden & Sotiropoulos,1997). In the present paper the corresponding analysis for compressiblematerials is detailed. In the two-dimensional context consideredfor incompressible materials the (homogeneous) plane waves werenecessarily shear waves. By contrast, in the compressible contextpure shear waves can propagate only in specific directions inthe considered principal plane and, in a general direction,a quasi-shear wave may be accompanied by a quasi-longitudinalwave, as is the case in the anisotropic linear theory. The dependenceof the (in-plane) slowness section on the pre-stress (and finitedeformation) and on the choice of constitutive law is elucidated.This information is used to determine the reflection coefficientsfor reflection of either a (quasi-) shear wave or a (quasi-)longitudinal wave from the boundary of the half-space and tocharacterize the different cases which arise depending on thegeometry of the slowness section. The theoretical results are illustrated by numerical calculationsfor the range of possible types of behaviour with referenceforms of strain-energy function and different states of finitedeformation and to the question of stability of the half-space. 相似文献