关键词: 微波辅助萃取, 吸收系数, 吸收功率密度, 微波频率, 介电常数

Abstract:

The absorption coefficient and absorption power density of microwave are two important physical quanti-ties to estimate the efficiency of microwave-assisted extraction. The former demonstrates the total proportion of mi-crowave energy absorbed by the solution , and the latter represents the conversion strength of thermal energy from microwave energy at any space point in the solution. In this paper , on the basis of the propagation law of micro-wave, an expression of absorption coefficient is derived as a function of solution permittivity. Then , according to the interaction between. microwave and solution , an analytical expression of absorption power density is also derived ,which is a function of the permittivity and the space coordinates. The two proposed expressions provide theoretical guidance for the selection of solvents in microwave-assisted extraction and the selection of microwave frequency in a specified solution.

Key words: microwave-assisted extraction, absorption coefficient, absorption power density, microwave frequençy, dielectric constant