文档介绍：International Journal of Heat and Mass Transfer 67 (2013) 955–966
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International Journal of Heat and Mass Transfer
journal homepage: ate/ijhmt
An experimental study on liquid nitrogen pipe chilldown and heat
transfer with pulse flows
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Reid Shaeffer, Hong Hu, . Chung
Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, United States
article info abstract
Article history: In order to provide the optimized chilldown strategy for a cryogenic transport line, a study on pulse flow
Received 1 May 2013 chilldown was conducted. parison between continuous flow and pulse flow patterns on heat trans-
Received in revised form 11 August 2013 fer characteristics was presented to reveal the effect of flow oscillation. Liquid nitrogen was used as the
Accepted 13 August 2013
working fluid and upward flows with Reynolds numbers ranging from 2500 to 7000 in a round tube were
Available online 24 September 2013
examined. To gain a better understanding of the effect of flow pulsation on the chilldown process, differ-
ent square wave pulse flow strategies were examined. Analysis of the ability of different flow patterns to
Keywords:
chill down transport lines indicated that there is no single best strategy for all boiling regimes and Rey-
Chilldown
nolds numbers. In terms of the efficiency, the continuous flow is optimal for most boiling regimes at low
Cryogenic
Flow boiling Reynolds numbers. On the other hand, pulse flow is ideal in the film boiling regime at higher Reynolds
Pulse flow numbers. In terms of the total efficiency, continuous flows with high Reynolds numbers are generally
more efficient at transferring heat than other patterns or those of lower Reynolds numbers. If a short
chilldown duration is a priority, the continuous flow consistently offers the quickest chilldown times.
A general guideline for chilldown strategy is suggested as a conclusion.
Ó 2013 Elsevier Ltd