TY - JOUR
T1 - Asymmetric annular flow in horizontal circular macro-channels
T2 - Basic modeling of liquid film distribution and heat transfer around the tube perimeter in convective boiling
AU - Mauro, A. W.
AU - Cioncolini, A.
AU - Thome, J. R.
AU - Mastrullo, R.
PY - 2014/10
Y1 - 2014/10
N2 - This paper presents the modeling of the liquid film distribution and heat transfer during convective boiling in horizontal, annular flows to be applied in such applications where non-uniform heat flux occurs. In general, prediction methods in the literature totally ignore the influence of the non-uniformity in the annular film (thin at top while thick at bottom) on the heat transfer process whereas local measurements around the perimeter of horizontal tubes show a significant variation, up to a factor of four times or more in thickness and up to 25-30% or more in heat transfer from top to bottom. Therefore, starting with the original suite for symmetrical annular flow models for convective boiling, condensation, entrainment, void fraction and two-phase pressure drops (Cioncolini and Thome (2009, 2011, 2012, 2012) [8-11]) and their recent paper (Cioncolini and Thome (2013) [13]) for predicting the threshold between symmetric and asymmetric annular flow, the new features added here are the predictions of the asymmetric annular film thickness and perimeter-wise heat transfer coefficients around the internal perimeter of horizontal tubes. To do this, a new set of 24 algebraic equations is proposed to provide the void fraction, liquid entrainment, pressure drop, liquid film distribution and heat transfer around the perimeter with a simple calculation procedure. Predictions of the new model have been compared against experimental databases with a satisfactory agreement.
AB - This paper presents the modeling of the liquid film distribution and heat transfer during convective boiling in horizontal, annular flows to be applied in such applications where non-uniform heat flux occurs. In general, prediction methods in the literature totally ignore the influence of the non-uniformity in the annular film (thin at top while thick at bottom) on the heat transfer process whereas local measurements around the perimeter of horizontal tubes show a significant variation, up to a factor of four times or more in thickness and up to 25-30% or more in heat transfer from top to bottom. Therefore, starting with the original suite for symmetrical annular flow models for convective boiling, condensation, entrainment, void fraction and two-phase pressure drops (Cioncolini and Thome (2009, 2011, 2012, 2012) [8-11]) and their recent paper (Cioncolini and Thome (2013) [13]) for predicting the threshold between symmetric and asymmetric annular flow, the new features added here are the predictions of the asymmetric annular film thickness and perimeter-wise heat transfer coefficients around the internal perimeter of horizontal tubes. To do this, a new set of 24 algebraic equations is proposed to provide the void fraction, liquid entrainment, pressure drop, liquid film distribution and heat transfer around the perimeter with a simple calculation procedure. Predictions of the new model have been compared against experimental databases with a satisfactory agreement.
KW - Annular flow
KW - Asymmetric
KW - Convective boiling
KW - Liquid film thickness
KW - Model
KW - Prediction
UR - http://www.scopus.com/inward/record.url?scp=84903839573&partnerID=8YFLogxK
U2 - 10.1016/j.ijheatmasstransfer.2014.06.021
DO - 10.1016/j.ijheatmasstransfer.2014.06.021
M3 - 文章
AN - SCOPUS:84903839573
SN - 0017-9310
VL - 77
SP - 897
EP - 905
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
ER -