Thermal wave analysis

Measurements on coated mold inserts, which were performed by thermal wave analysis, have shown that the heat insensitivity of the individual coatings shows significant differences. Figure 2.111 shows the depth profiles of the heat insensitivity for different mold coatings. 

Along with the methods of similarity theory, Ya.B. extensively used and enriched the important concept of self-similarity. Ya.B. discovered the property of self-similarity in many problems which he studied, beginning with his hydrodynamic papers in 1937 and his first papers on nitrogen oxidation (25, 26). Let us mention his joint work with A. S. Kompaneets [7] on selfsimilar solutions of nonlinear thermal conduction problems. A remarkable property of strong thermal waves before whose front the thermal conduction is zero was discovered here for the first time their finite propagation velocity. Independently, but somewhat later, similar results were obtained by G. I. Barenblatt in another physical problem, the filtration of gas and underground water. But these were classical self-similarities the exponents in the self-similar variables were obtained in these problems from dimensional analysis and the conservation laws. 

Another feature of the breakthrough method is that the uniform geometry of the packed column permits fairly straightforward analysis of the thermal waves produced due to heats of adsorption, and of their effect on the shape of the sorption fronts. The most obvious advantage of this method, however, is the fact that the results of the breakthrough experiments can be applied rather directly to the design of commercial adsorbers, with relatively little analysis of the data. 

The background here shares a common origin with the background on the adsorption wave through the old work of Anzelius [A. Anzelius, Zeits. fiir Ang. Math, und Mech., 6, 291 (1926)], Schumann [T.B. Schumann, J. Frank. Inst., 208, 405 (1929)] and Furnas [C.C. Furnas, U.S. Bureau of Mines Bull., 361, (1932)], so we can legitimately slip in this analysis of thermal waves. 

Pan, C. J. Basmadjian, D. An Analysis of Adiabatic Sorption of Single Solutes in Fixed Beds Pure Thermal Wave Formation and it s Practical Implications, Chem. Eng. Sci 25 (1970), p. 1653/1664... 

F. Trager, Surface analysis by laser-induced thermal waves. Laser Optoelektron. 18, 216 (1986) ... 

Sij = +1 for total reflection and s,y = — 1 for total absorption of (plane) thermal waves incident on an interface. Subsurface reflection or absorption may result in measurable surface temperature change. Surface temperature changes obtained by scanning an excitation beam across the sample surface may contain subsurface information limited to the depth of the thermal diffusion length. The subsurface thermal image may thus be obtained by analysis of the surface temperature change. 

Power JF (1989) Thermal wave imaging in the physicochemical analysis and evaluation of solid-phase samples. Progress in Analytical Spectroscopy 12 453-506. 

Thermal Diffusivity Measurement by Temperature Wave Analysis (TWA)... 

The temperature modulation technique is advantageous for observing the complex physical properties in the relaxation region. The temperature wave analysis (TWA) method is a nonsteady-state method for measuring the thermal diffusivity of materials. 

Pan, C.Y., and Basmadjian, D., Analysis of adiabatic sorption of single solutes in fixed beds Pure thermal wave formation and its practical implications, Chem. Eng. Sci., 25(11), 1653-1664 (1970). 

The analysis above is performed for a stack operated in the potentiostatic regime (constant r °). In this regime, propagation of the thermal wave causes growth of the stack current the respective variation of the mean current density J can be obtained from... 

Thermal scanning microscopy Temperature-time profile Time/temperature resolved pyrolysis mass spectrometry Thermal ultraviolet Thermal volatilisation analysis Thermal wave infrared imaging Transmission X-ray microscopy Total-reflection X-ray fluorescence (c/r. TRXRF) Ultrasonic force microscopy Ultraviolet photoelectron spectroscopy Ultrasound... 

Netzelmann, U., Thermal Wave Micro Analysis for Testing of Adhesion Bonding, Materialprufung, Materials Testing, Materiaux Essais et Recherches, 38(6) 246-249 (1996)... 

That some enhancement of local temperature is required for explosive initiation on the time scale of shock-wave compression is obvious. Micromechanical considerations are important in establishing detailed cause-effect relationships. Johnson [51] gives an analysis of how thermal conduction and pressure variation also contribute to thermal explosion times. 

---