Thermal-cooled module

Mechanical Failures Cracks or debonding of the catalyst from the substrate material can occur from thermal stresses as well as dynamic forces on the modules. The catalyst must be carefully handled to prevent premature fracturing. Each requires a warm-up and cool-down rate. 

Jones, S., and E. Khanishian, Numerical Thermal Analysis of an Oil-Cooled Hybrid IGBT Switch Module for High-Power Inverter/Converter Applications, Eroc. of the 2003 U.S. Army Collaborative Technology Alliances Conf.—Power and Energy, April 29-May 1, 2003, pp. 149-153. 

Photoacoustic Spectroscopy.7 When modulated IR radiation is absorbed by a sample, the substance heats and cools in response to modulated IR energy impinging on it. This thermal hysteresis is converted into pressure waves that can be communicated to surrounding gases and detected by acoustic detectors (essentially a sensitive microphone in the enclosed sample chamber). In such measurements, the acoustic detector replaces the IR detector of the spectrometer. 

The temperature tuning coefficient of Te02 is 0.025 nm/°C, so it is clear that in order to combat the effects of thermal heating of the crystal due to incident optical and acoustic power, as well as environmental considerations, a good level of thermal control is needed. This can be in the form of a TE-cooled enclosure. This will deal to a certain extent with the need to achieve analyser wavelength repeatability. However, it does not address the issue of wavelength reproducibility between AOTF modules, which impacts the transportability of calibrations and datasets between analysers. 

More complex temperature programmes are sometimes useful. These might combine periods of variable heating and cooling rates with isothermal periods. For example, stepwise heating can be used to detect the onset of melting under quasi-isothermal conditions (Laye, 2002). Modulated temperature DSC (MTDSC), in which the linear temperature scan is perturbed by a sinusoidal, square or saw-tooth wave, or other modulation of temperature, has a number of potential advantages over the conventional linear scan. These include increased sensitivity and resolution, and the ability to separate multiple thermal events (Laye, 2002). 

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