The study of the theory of the colloid mill drying technology can be summed up space for low pressure and low temperature heat and qualitative theory research and thermal physical property parameters and their measurement method research three parts. Of low pressure low temperature heat and mass transfer theory research going early, the obvious achievements, recognized as a colloid mill model can be summarized into three types:
(1) 1967 Sanda11 steady state model is proposed for uniform interface of ice backwards (URIF).
(2) the quasi-steady state model of the Dryer, 1968.
(3) 1979Litchield such as adsorption distillation model is put forward.
This model can describe the process of colloid mill, but there is insufficient, describe the heat transfer process more accurate, error description and mass transfer process. Main problem is to occur during the process of mass transfer of solid - phase change of the vapor phase, water vapor transfer in the porous channel, channel length will change over time, is a steady-state process. The structure of the porous channel size and precool speed, be concerned by the material structure of colloid mill products. Haven't seen from recent research reports have new breakthrough.
Colloid mill process theory focuses on research of heat mass transfer occurs during the process of colloid mill material inside. The study of the theory of the unsteady flow field focuses on the research material, low pressure low temperature within the colloid mill space environment, describes the parameters of the space environment parameters such as temperature, pressure, humidity, the unsteady flow field simulation method is still a difficult problem. Colloid mill condenser increased again in the unsteady flow field in a steam - solid phase change problem, make the study more complicated. Therefore, although some research in recent years, and published papers, but did not form effective theory, one of the subject is still worthy of further study.