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Novel real-time diagnosis of the freezing process using an ultrasonic transducer.

Tseng YH, Cheng CC, Cheng HP, Lee D - Sensors (Basel) (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. yhtntut@gmail.com.

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.

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(a) Typical ultrasonic signals acquired by UT; (b) the frequency spectrum of L1 signal. The center frequency of the L1 echo was 8.51 MHz, and the 3-dB bandwidth was 8.70 MHz.
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sensors-15-10332-f003: (a) Typical ultrasonic signals acquired by UT; (b) the frequency spectrum of L1 signal. The center frequency of the L1 echo was 8.51 MHz, and the 3-dB bandwidth was 8.70 MHz.

Mentions: Figure 3a shows the typical ultrasonic signals acquired with the UT in Figure 2. As one can see, the Ln echoes (n = 1, 2, …), reflected at the bottle/water or ice interface, appeared at 0.81 and 1.87 μs, respectively, and remain during the entire process. When the water was not frozen, the Lw echo, propagating in the water and reflected at the water/air interface, was observed at 36.39 μs. The time delay difference between the L1 and Lw echoes was denoted as Δt. Figure 3b shows the frequency spectrum of the L1 echo in Figure 3a. The center frequency of the L1 echo was 8.51 MHz, and the 3-dB bandwidth was 8.70 MHz. The SNR for the first round trip echo, L1, was 37.6 dB. The SNR value could be calculated according to the following equation:(1)SNRdB=10log10(PL1PNoise)=20log10(AL1ANoise)where P and A are the power and amplitude of signals, respectively.


Novel real-time diagnosis of the freezing process using an ultrasonic transducer.

Tseng YH, Cheng CC, Cheng HP, Lee D - Sensors (Basel) (2015)

(a) Typical ultrasonic signals acquired by UT; (b) the frequency spectrum of L1 signal. The center frequency of the L1 echo was 8.51 MHz, and the 3-dB bandwidth was 8.70 MHz.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4481992&req=5

sensors-15-10332-f003: (a) Typical ultrasonic signals acquired by UT; (b) the frequency spectrum of L1 signal. The center frequency of the L1 echo was 8.51 MHz, and the 3-dB bandwidth was 8.70 MHz.
Mentions: Figure 3a shows the typical ultrasonic signals acquired with the UT in Figure 2. As one can see, the Ln echoes (n = 1, 2, …), reflected at the bottle/water or ice interface, appeared at 0.81 and 1.87 μs, respectively, and remain during the entire process. When the water was not frozen, the Lw echo, propagating in the water and reflected at the water/air interface, was observed at 36.39 μs. The time delay difference between the L1 and Lw echoes was denoted as Δt. Figure 3b shows the frequency spectrum of the L1 echo in Figure 3a. The center frequency of the L1 echo was 8.51 MHz, and the 3-dB bandwidth was 8.70 MHz. The SNR for the first round trip echo, L1, was 37.6 dB. The SNR value could be calculated according to the following equation:(1)SNRdB=10log10(PL1PNoise)=20log10(AL1ANoise)where P and A are the power and amplitude of signals, respectively.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan. yhtntut@gmail.com.

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.

Show MeSH
Related in: MedlinePlus