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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

HEAT TRANSFER ANALYSIS FOR COOLING PROCESS OF LIQUID NITROGEN UTILIZING THIN FILM EVAPORATION

Fengmin Su
Marine Engineering College, Dalian Maritime University, Dalian, Liaoning 116026 China

Zhongyu Ma
Institute of Marine Engineering and Thermal Science, Dalian Maritime University, Dalian, 116026, China

Nannan Zhao
Institute of Marine Engineering and Thermal Science, Dalian Maritime University, Dalian, 116026, China

Yangbo Deng
Institute of Marine Engineering and Thermal Science, Dalian Maritime University, Dalian, 116026, China

Hongbin Ma
Marine Engineering College, Dalian Maritime University, Dalian, Liaoning 116026 China; Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri, 65211, USA

DOI: 10.1615/IHTC16.bae.022227
pages 689-697


KEY WORDS: Boiling and evaporation, Bio and medical applications, cell cryopreservation, ultra-fast cooling

Abstract

Vitrification is one of effective methods for cell cryopreservation. An ultra-fast cooling rate is beneficial to improve the vitrification level of the extra and intracellular solution and decrease the concentration of cryoprotectant. A novel ultra-fast cooling method utilizing thin film evaporation was developed. In it, a frozen carrier with a microstructured layer was produced. Liquid nitrogen, serving as the working fluid, was dispersed into the microstructured layer by capillary force, and evaporated at a high speed. Due to this quick evaporation and heat absorption, the frozen carrier was ultra-fast cooled. This study analyzed the transient heat transfer of this cooling method by experiments and numerical simulations and optimized it to achieve higher cooling rate. The numerical results were agreed with the corresponding experimental data very well. The results showed that the evaporation heat transfer of liquid nitrogen is the key factor. Enhancing the thin film evaporation of liquid nitrogen by optimizing the morphology of the microstructured surface can improve the cooling rate obviously. The temperature distribution within the frozen carrier is almost homogeneous in the whole cooling process because the conductive thermal resistance within the carrier is obviously lower than that of the liquid nitrogen evaporation on the surface of the frozen carrier. This ensures that all of cells in the suspension can achieve the same cooling rate in the whole frozen process. The current investigation will support better the development of the novel vitrification method.

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