Experimental Study of Vacuum Freeze-Drying for Acid-Processed Paper Relics

In this paper, a vacuum freeze drying equipment was developed for vacuum deacidification of paper relics. The relation between freezing velocity and sample mass was studied experimentally, so did the relation between freezing velocity and pre-freezing time. The results indicated freezing velocity is inversely proportional to sample mass as well as the time used with refrigerating capacity equal to mass fraction of frozen water. Problems like melting or disintegration can be overcome by heating gradually. Radiation heating combined with conduction heating make sure the sample is heated evenly. Moreover, vacuum deacidification is available to remove acid of paper relics, and paper relics are kept intact by means of vacuum freeze-drying.