Development of New Refrigeration System for Pharmaceutical Freeze Dryers

Abstract

With extending use of pharmaceutical freeze dryers, the equipment have remarkably been improved lately. Unfortunately, in the opinion of some including both users and makers of the freeze dryer, the development of refrigeration system required for freeze dryers has not kept pace with advances in other component area. As compared with the conventional refrigeration system shown in Fig. 1-a, the system in Fig. 1-b which covers both vapor condenser load and shelf-cooling load with refrigerated brine circuation, ensures higher reliability on the temperature control, but is yet to be widely used because the system requires rather excessive refrigeration equipment in which energy consumption is comparatively bigger. Now, through the development of New Rifrigeration system indicated in Fig. 1-c, we have succeeded in combining the advantages of the aforesaid two systems, also eliminating their drawbacks. Features of our new system called "Triple Heat-Exchange Trap" system are that an array of plates in the vapor trap chamber serves as a heat exchanger with three effects; i.e. heat transfer between refrigerant and brine (1), between water vapor and refrigerant (2) and between water vapor and brine (3). With this new system, precise and easy control of the vapor trap is ensured without adoption of excessive refrigeration equipment and without excessive energy consumption.