Prediction of refrigerant flow boiling hysteresis with an augmented separated-flow model

Jianwei Gao, Hongxia Li, Saif Almheiri, Tie Jun Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Thermal management is essential to compact devices particularly for high heat flux removal applications. As a popular thermal technology, refrigeration cooling is able to provide relatively high heat flux removal capability and uniform device surface temperature. In a refrigeration cycle, the performance of evaporator is extremely important to the overall cooling effi- ciency. In a well-designed evaporator, effective flow boiling heat transfer can be achieved whereas the critical heat flux (CHF) or dryout condition must be avoided. Otherwise the device surface temperature would rise significantly and cause device burnout due to the poor heat transfer performance of film boiling. In order to evaluate the influence of varying imposed heat fluxes, saturated flow boiling in the evaporator is systematically studied. The complete refrigerant flow boiling hysteresis between the imposed heat flux and the exit wall superheat is characterized. Upon the occurrence of CHF at the evaporator wall exit, the wall heat flux redistributes due to the axial wall heat conduction, which drives the dryout point to propagate upstream in the evaporator. As a result, a significant amount of thermal energy is stored in the evaporator wall. While the heat flux starts decreasing, the dryout point moves downstream and closer to the exit. The stored heat in the wall dissipates slowly and leads to the delay in rewetting or quenching, which is the key to understand and predict the flow boiling hysteresis. In order to reveal the transient heat releasing mechanism, an augmented separated-flow model is developed to predict the moving rewetting point and minimum heat flux at the evaporator exit, and the model predictions are further validated Address all correspondence to this author. by experimental data from a refrigeration cooling testbed.

Original languageBritish English
Title of host publicationMicro/Nano-Thermal Manufacturing and Materials Processing; Boiling, Quenching and Condensation Heat Transfer on Engineered Surfaces; Computational Methods in Micro/Nanoscale Transport; Heat and Mass Transfer in Small Scale; Micro/Miniature Multi-Phase Devices; Biomedical Applications of Micro/Nanoscale Transport; Measurement Techniques and Thermophysical Properties in Micro/Nanoscale; Posters
ISBN (Electronic)9780791849668
DOIs
StatePublished - 2016
EventASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016 - Biopolis, Singapore
Duration: 4 Jan 20166 Jan 2016

Publication series

NameASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016
Volume2

Conference

ConferenceASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016
Country/TerritorySingapore
CityBiopolis
Period4/01/166/01/16

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