The desiccants such as silica gel

active alumina

active carbon

and molecular sieve

are employed to purify the contaminations in the refrigerant system.With the development of new refrigerants

the properties of desiccants need to be improved.Based on the analysis on the different preparations of the desiccants

the following two concepts were presented:(1) to increase water capacity and compatibility with the refrigerants or the refrigeration oil;(2) to simplify the techniques and to reduce the cost.Because of homogeneous aperture of the molecule structure

high specific surface area

and selectivity adsorption

the molecular sieve desiccant is the most applicable desiccant material.It is necessary for us to study the molecular sieve desiccant preparation techniques and the modification of the molecular sieve.