USING SURFACE HEAT FLUX MEASUREMENT TO MONITOR AND CONTROL A FREEZE DRYING PROCESS

摘要

A method of monitoring and controlling a freeze drying process in a freeze drying apparatus having walls, shelves and a number of vials or trays positioned on different areas of the shelves and containing product to be freeze dried. One or more vials or trays are selected that are representative of the positions of all of the vials or trays in different areas of the shelves. One or more heat flux sensors are positioned between the selected vials or trays and adjacent portions of the walls and/or shelves. The heat transfer between the selected vials or trays and the adjacent wall or shelf portions is measured during the freezing and drying stages of the freeze drying process.

主权项

1. A method of monitoring and controlling a freeze drying process in a freeze drying apparatus having walls, one or more shelves and one or more vials or trays positioned on different areas of the shelves and containing product to be freeze dried, comprising:
selecting one or more vials or trays that are representative of the positions of all of the vials or trays in different areas of the shelves, positioning one or more heat flux sensors between the selected vials or trays and adjacent portions of the walls and/or shelves, measuring the heat flow between the selected vials or trays and adjacent wall or shelf portions during a freezing stage of the freeze drying process, and controlling the shelf temperature to keep the heat flow at a predetermined level throughout a crystal growth phase of freezing to produce a homogeneous ice crystal structure in the product during the freezing stage.