A study of thermophysical properties of substances by nuclear magnetic resonance.

摘要

This thesis presented research in the interdisciplinary fields of nuclear magnetic resonance (NMR) and thermophysics with emphasis on the use of NMR to study thermophysical properties of substances such as thermal diffusivity, thermal conductivity and specific heat, and heat transfer coefficient parameters of fluid and particle systems. The thesis addresses experimental and theoretical problems in the use of magnetic resonance imaging for practical measurements of thermophysical properties of substances. The temperature dependence of nuclear magnetic resonance parameters studied and relations for the nuclear thermal coefficients are developed over the temperature range commonly used in processing liquids and in NMR thermometry for the thermal treatment of tissues and tumors in medicine. In this study, a special emphasis is given to the temperature dependence of magnetization in a much wider treatment involving a large number of magnetic resonance imaging sequences such as spin echo imaging, gradient echo imaging, spin-echo echo planar imaging and gradient-echo echo planar imaging, with variations of nuclear thermal coefficient contrasts such as spin spin nuclear relaxation time, spin lattice nuclear relaxation time, nuclear spin self diffusion coefficient, nuclear magnetic resonance frequency and nuclear spin phase shift and finally these methods are used for the measurement of temperature and thermophysical parameters for a number of applications ranging from chemistry to medicine.