CIESC Journal ›› 2020, Vol. 71 ›› Issue (11): 5117-5128.DOI: 10.11949/0438-1157.20200301

• Fluid dynamics and transport phenomena • Previous Articles     Next Articles

Effect of ultrasonic on freezing state and heat transfer of droplet

Jian CONG1(),Penghui GAO1,2(),Donghai ZHANG1,2,Jinpeng ZHOU3,Zhenghan ZHANG3   

  1. 1.School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
    2.State Key Laboratory for GeoMechanics and Deep Underground Engineering, Xuzhou 221116, Jiangsu, China
    3.International College, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
  • Received:2020-03-23 Revised:2020-06-11 Online:2020-11-05 Published:2020-11-05
  • Contact: Penghui GAO

超声波对液滴冻结状态及传热的影响

丛健1(),高蓬辉1,2(),张东海1,2,周晋鹏3,张正函3   

  1. 1.中国矿业大学力学与土木工程学院,江苏 徐州 221116
    2.中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏 徐州 221116
    3.中国矿业大学国际学院,江苏 徐州 221116
  • 通讯作者: 高蓬辉
  • 作者简介:丛健(1995—),男,硕士研究生,15715207607@163.com
  • 基金资助:
    国家自然科学基金项目(51876218)

Abstract:

Ultrasonic -assisted freezing has been widely used in food, medical and biochemical fields. To clarify the effect of ultrasonic wave on the variations of liquid-solid ratio and void ratio in freezing state, and to reveal heat transfer law in the process of freezing transformation, the mathematical model of ultrasonic droplet freezing was established which was combined with the theory of acoustics and heat & mass transfer based on the experiment. The droplet freezing state under the action of ultrasound was analyzed, and the heat dissipation caused by ultrasonic cavitation effect and heat production caused by ultrasonic thermal effect was compared. The result shows that the ultrasonic wave is helpful to bubble overflow on surface of the droplet, and the larger the overflow rate is, the smaller the liquid-solid ratio is in the freezing process; when the bubble overflows is certain, the smaller the droplet is, the larger the porosity is; when the ultrasonic wave is certain, the smaller the overflow rate is, the larger the porosity is in the freezing process; for the cooling and freezing process, there is a reasonable ultrasonic loading time for different ultrasound frequencies and intensities.

Key words: ultrasound, freezing state, heat and mass transfer

摘要:

超声波辅助冻结在食品、医疗及生物化学等领域得到了广泛的应用,为了明确超声波对溶液冻结过程中液固比例、孔隙率的影响,揭示冻结过程中热量的传递规律,在液滴冻结状态实验观测的基础上,结合声学及热质传递理论,建立了超声波液滴冻结理论模型,分析了超声波对液滴冻结状态的影响,比较了超声空化效应所引起的传质散热量和超声热效应引起的产热量的大小关系。结果表明:超声波有助于液滴表面的气泡逸出,气泡逸出率越大冻结过程中液固比例越小;当气泡逸出率一定时,液滴越小冻结过程中的孔隙率越大;超声波一定时,逸出率越小冻结过程中的孔隙率越大;对于冷却冻结过程,不同频率和强度的超声波存在合理的超声波加载时间。

关键词: 超声波, 冻结状态, 传热传质

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