Temperature measurements using a birefringent sensor

An optical method for temperature measurements is proposed based on the use of an autocollimation polarimeter and a sensitive birefringent plate. The basic expressions that describe the operation of the system are presented. It is shown that with the use of a quartz plate 1.5 mm thick the device makes it possible to determine values of temperature in the region of –80 to +150°C.Academic Scientific Complex A. V. Luikov Institute of Heat and Mass Transfer of the Academy of Sciences of Belarus, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 5–6, pp. 475–482, November–December, 1994.     

Obtaining superadiabatic temperatures in combustion of gaseous fuel in a system of two porous plates with a periodic change of the direction of pumping

A mechanism of obtaining superadiabatic temperatures in a system of two porous plates is theoretically investigated. Data on the optimum pumping periods and on the value of the produced superadiabatic effect are presented.Academic Scientific Complex A. V. Luikov Institute of Heat and Mass Transfer of the Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 64, No. 5, pp. 569–576, May, 1993.     

Development of the Method of Characteristics for a System of Maxwell Electrodynamic Equations

Expressions for the velocities of propagation of the discontinuity surfaces in a homogeneous anisotropic medium have been obtained and equations of bicharacteristics have been derived. Using them, the surfaces of inverse velocities and threedimensional wave fronts of electromagnetic waves have been constructed for different values of the permittivities and their features have been investigated.     

Radar–Spectrometric Method for Determining the Characteristics of Radioactive Emission

The uncertainty of the measurement geometry – absence of information about shape, dimensions, activity distribution, and spatial position of the radioactive cloud relative to the detector location – makes it difficult to perform spectrometry of radioactive emissions, for example, from nuclear power plants. The combined use of spectrometer and radar-tracer method, which visualizes a radioactive cloud, makes it possible to switch from qualitative analysis of spectra to determination of quantitative content of radionuclides in the emission. Schemes for radar-spectrometric probing and the basic computational relations for determining the activity of radionuclides are examined.     

On determination of the basic characteristics of free convective heat exchange near a flat vertical surface

The results of mathematical modeling of free convective heat exchange near a semiinfinite, impermeable, flat vertical surface have been presented. The features of velocity and temperature fields as functions of the boundary conditions and the Prandtl number have been studied. Tables of numerical solutions have been given. The esults obtained have been compared to the numerical data of other authors. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 74–79, July–August, 2007.     

Evaluation of Mass Transfer Resistances from Drying Experiments

A new approach to experimental evaluation of mass transfer resistances from drying experiments is proposed. A composite model of ginseng root mass transfer, based on one-dimensional treatment of diffusive and convective resistances as additive components of radial mass transfer, was developed. Mass transfer resistance was evaluated from a linear relationship between measured flux and thermodynamic driving force. Partitioning of mass transfer resistance into diffusive (core and skin) and convective (air boundary layer) resistances was done by modification of boundary conditions: (a) high (3 m/s) and low (1 m/s) air velocity; (b) skin removal. Total radial mass transfer resistance was evaluated as (146 ± 6) ? 10⁶ s/m at 38°C, significantly decreasing to (48 ± 1.5) ? 10⁶ s/m at 50°C. Boundary resistance was evaluated as (54 ± 5) ? 10⁶ s/m at 38°C and (26 ± 3) ? 10⁶ s/m at 50°C in the entire range of moisture contents. Core and skin resistances were both moisture dependent: core resistance increased from initial value of (6 ± 1) ? 10⁶ s/m to (61 ± 6) ? 10⁶ s/m toward the end of drying, whereas skin resistance decreased from initial value of (92 ± 5) ? 10⁶ s/m to (25 ± 5) ? 10⁶ s/m at the endpoint of drying. However, the sum of core and skin resistances, which represents composite diffusive resistance of intact ginseng root, was constant and independent of moisture content: (91 ± 4.6) ? 10⁶ s/m at 38°C and (22 ± 1.6) ? 10⁶ s/m at 50°C. The relationship between mass transfer resistance R and drying rate factor k = 1/RC was used for verification of the composite model.