Development of Vacuum Freeze-Drying System

• Main Authors: Chia-Chi Hsu, 許佳琪
• Other Authors: 鄭鴻斌
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/6bd696

碩士 === 國立臺北科技大學 === 冷凍空調工程系所 === 93 === Vacuum freeze-drying is by solidifying the dry object by means of rapid freezing, then sublime the ice into water vapor under appropriate vacuum conditions to eliminate the water content in the object. Vacuum freeze-drying includes three procedures, namely lyophilization, low-temperature low-pressure air extraction, and desorption process. The low-temperature freezing system includes two parts, one is for pre-freezing, and another is for condenser. It mainly uses Cascade system to supply low temperature down to -85℃. The vacuum system uses dry vacuum pump for air extraction to offer advantage of zero oil gas pollution. The desorption process uses a set of circulating water tank heating system to provide plate heat source to aid the product reaching rapid drying. This study developed vacuum freeze-drying equipment for pharmaceutical and biotechnology industries, used vacuum freeze-dried 20% glucose solution and 20% saline solution to carry out vacuum drying on the samples, while the temperatures of the plates in preliminary drying were 20℃, 10℃, 0℃, -10℃ and -20℃, in order to discuss the effect of different plate temperatures on the sample temperature, pressure, and dryness. The experiment revealed that as the plate temperature is low and close to the sample temperature, the dryness is more satisfactory and the appearance is more intact. When the water loss for 20% glucose solution under plate temperature of -20C could reach 88%, and the appearance included irregular pores after freeze-dried. The water loss for 20% saline solution could reach 82%, and the appearance was more intact and showed loose chunks. During the drying process, low temperature measuring device and vacuum pressure gauge were installed to analyze the air extraction process, pressure change, and temperature change of the drying samples. The freezing temperature, air extraction speed, ultimate pressure, and water content of the dried products were measured. Micro observation system was used to observe the shape change of the product during the freeze-drying process in dynamic and real-time manner, thus, to ensure the product quality.