Journal of South China University of Technology (Natural Science Edition) ›› 2007, Vol. 35 ›› Issue (4): 52-57.

• Chemistry & Chemical Engineering • Previous Articles     Next Articles

Absorption Coefficient and Absorption Power Density of Microwave in Microwave-Assisted Extraction

Han Guang-ze1  Chen Ming-dong1  Guo Ping-sheng2  Li Shao-xin1   

  1. 1. School of Physics , South China Univ. of Tech. , Guangzhou 510640 , Guangdong , China;2. College of Physics and Electronic Engineering， Guangxi Normal Univ. , Guilin 541004 , Guangxi , China
  • Received:2006-10-13 Online:2007-04-25 Published:2007-04-25
  • Contact: 韩光泽(1964-)，男，博士，教授，主要从事工程热物理及理论物理研究. E-mail:phgzhan@scut. edu.cn
  • About author:韩光泽(1964-)，男，博士，教授，主要从事工程热物理及理论物理研究.
  • Supported by:

    国家自然科学基金资助项目(10674048) ;传热强化与过程节能教育部重点实验室基金项目

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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