title: Novel real-time diagnosis of the freezing process using an ultrasonic transducer.
abstract: The freezing stage governs several critical parameters of the freeze drying process and the quality of the resulting lyophilized products. This paper presents an integrated ultrasonic transducer (UT) in a stainless steel bottle and its application to real-time diagnostics of the water freezing process. The sensor was directly deposited onto the stainless steel bottle using a sol-gel spray technique. It could operate at temperature range from -100 to 400 °C and uses an ultrasonic pulse-echo technique. The progression of the freezing process, including water-in, freezing point and final phase change of water, were all clearly observed using ultrasound. The ultrasonic signals could indicate the three stages of the freezing process and evaluate the cooling and freezing periods under various processing conditions. The temperature was also adopted for evaluating the cooling and freezing periods. These periods increased with water volume and decreased with shelf temperature (i.e., speed of freezing). This study demonstrates the effectiveness of the ultrasonic sensor and technology for diagnosing and optimizing the process of water freezing to save energy.
authors.affiliation: Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. yhtntut@gmail.com.
authors.forename: Yen-Hsiang
authors.initials: YH
authors.lastname: Tseng
authors.affiliation: Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. newmanch@ntut.edu.tw.
authors.forename: Chin-Chi
authors.initials: CC
authors.lastname: Cheng
authors.affiliation: Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. hpcheng7@gmail.com.
authors.forename: Hong-Ping
authors.initials: HP
authors.lastname: Cheng
authors.affiliation: Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. f11167@ntut.edu.tw.
authors.forename: Dasheng
authors.initials: D
authors.lastname: Lee
mesh_terms: D005612:Freeze Drying / Q000379:methods; D005615:Freezing; D013696:Temperature; D014465:Ultrasonics