MICROWAVES LIQUID-PROBE EFFECTIVE ABSORPTION MEASUREMENT USING A MICROWAVE POWER CALORIMETRIC METHOD

Ildiko Bros, E.Surducan, V.Surducan

National Institute for research and development of Isotopic and Molecular Technologies,  
75-103 Donath Street, POB 700, Cluj Napoca, email: ildiko@l30.itim-cj.ro

	The basic principles of microwave treatments are: direct energy transfer in the probe sample and the selectivity of microwave absorption which depends by the dielectric loss of the probe. These two characteristics imply a time rate of treatments between 2 to 1000 comparatively with classical processes. 	
	For determination of the optimal process conditions in microwaves power treatment it is necessary an experimental determination of the power absorption value for a particular treated system because:
•	the microwaves power have a specific distribution inside the extraction cell as a function of the probe nature connected to the cell shape and the dielectric properties changes with the temperature;
•	the selectivity in absorption imply a very large temperature distribution in a mixture and the probe damage possibility;
In this material we present a very simple calorimetric methode to measure the power absorption rate for a specific probe. What is new is the temperature measurement methode inside of the treatment cell. The classical temperature sensors can not be used because of the local strenght of the electromagnetic filed. Our solution overrides this inconvenient (fig.1).

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Fig.1 Experimental configuration with the temperature sensor dedicated to the microwaves treatments of liquid probes 
(1 – treatment cell; 2- temperature probe; 3-command unit with temperature read-out)