TY - GEN
T1 - Prediction of refrigerant flow boiling hysteresis with an augmented separated-flow model
AU - Gao, Jianwei
AU - Li, Hongxia
AU - Almheiri, Saif
AU - Zhang, Tie Jun
N1 - Funding Information:
This work was funded by the Cooperative Agreement between the Masdar Institute of Science and Technology (Masdar Institute), Abu Dhabi, UAE and the Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
Publisher Copyright:
© 2016 by ASME.
PY - 2016
Y1 - 2016
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84969820596&partnerID=8YFLogxK
U2 - 10.1115/MNHMT2016-6522
DO - 10.1115/MNHMT2016-6522
M3 - Conference contribution
AN - SCOPUS:84969820596
T3 - ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016
BT - Micro/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
T2 - ASME 2016 5th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2016
Y2 - 4 January 2016 through 6 January 2016
ER -