Spijkers, Rick

Vanapalli, S.

English

University of Twente Research Information

Evaporation of liquid nitrogen in a microchannelRick Spijkers 1, Srinivas Vanapalli1 r.m.a.spijkers@utwente.nlDry-shipperAs a model problem the effect of evaporation on the imbibition of liquids into a micro-channel is experimentally investigated to give insight in the micro-scale physics.A microchannel as a model problem for porous  mediaProgress on the measurement of boiling delay for liquid nitrogen in a capillary channelThe length of the liquid column L measured as a function of time.2𝜎 cos(𝜃)𝐷Laplace=12𝜇𝐿𝐷2𝑈Liquid viscosity+ฏ𝑗2𝜌𝑣Vapor recoil+12𝜇𝐿𝐷2𝑈Vapor viscosityTheorical Lucas-Washburn type model for evaporation2Microchannel2𝜎 cos(𝜃)𝑅poreLaplace=𝜇𝜙𝐿𝐾𝑈Viscosity (Darcy′s law)+ evaporation termPorous mediaAnalogous physics                                                                           Lucas-Washburn without evaporation: Viscous term/Laplace term = 1A dry-shipper is a solution to transport for frozen biomedical samples at a temperature below -150 °C. This temperature ismaintained with liquid nitrogen that is absorbed in a porous lining inside the container. The performance of a dry-shipper, forexample the preparation time or the cleanability, is dependent on the interplay between the liquid and the porous materialproperties. Due to the large temperature difference between the room temperature porous material and liquid nitrogen,there is heavy evaporation during absorption, which is not very well understood. The model problem of liquid nitrogenabsorbing into a transparent, temperature controlled, and well defined microchannel is studied to investigate the physicson the pore scale.                                            Below saturation temperatureIncreased velocity with temperature due to viscosity and surface tensionAbove saturation temperatureReduced velocity with temperature due to evaporationExperimental procedure• Deposit droplet on the entrance to the channel• Record absorption process using a high-speed cameraAdaptation of the test rig to cryogenic temperatures• Vapor free droplet generator3• Temperature controlled surface 70 - 85 K• Helium environment• Optical access through thermal insulation1. Applied Thermal Sciences, University of Twente,  The Netherlands 2. Ramon, G., & Oron, A. (2008). Capillary rise of a meniscus with phase change. Journal of Colloid and Interface Science, 327(1), 145–151.3. Schremb, M., Kalter, M., & Vanapalli, S. (2023). Development of a lab-device for evaporation-free supply of pure liquid nitrogen for droplet- and jet-generation. Scientific Reports, 13(1), 1–13.The material, thermodynamic and transport properties at cryogenic temperature vary strongly compared to room temperature, therefore a subsequent study with cryogenics liquids will be performed.Boiling delay at room temperature Adapting to cryogenic liquidsA photo and a SEM image of the porous calciumsilicate material that also lines the inside of the dry-shipper.T - Tsat = -51,8 °C T - Tsat = +11,7 °CAt elevated superheat, the liquid oscillates into and out off the channel.

Evaporation of liquid nitrogen in a microchannel:Progress on the investigation of the delay in boiling of liquid nitrogen in a capillary channel

https://ris.utwente.nl/ws/files/330391872/Rick-CECposterV0.2.pdf

Evaporation of liquid nitrogen in a microchannel:Progress on the investigation of the delay in boiling of liquid nitrogen in a capillary channel

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