Stephens, Darrin W; Harris, Jonathan A Prediction of evaporation, pressure driving force, and heat transfer in calandria tubes Conference Australian Society of Sugar Cane Technologists, 24 , 2002. Abstract | Links | BibTeX | Tags: Boiling, Calandria Tube, Evaporation, Heat Transfer, Model, Vacuum Pan @conference{stephens2002prediction,
title = {Prediction of evaporation, pressure driving force, and heat transfer in calandria tubes},
author = {Darrin W Stephens and Jonathan A Harris},
doi = {10.13140/RG.2.1.3571.4403},
year = {2002},
date = {2002-01-01},
booktitle = {Australian Society of Sugar Cane Technologists},
journal = {PROCEEDINGS-AUSTRALIAN SOCIETY OF SUGAR CANE TECHNOLOGISTS},
volume = {24},
abstract = {A heat transfer model of boiling flow in steam heated calandria tubes is presented. The model predictions for vapour formation, heat transfer and pressure difference are compared with experimental data and yield reasonable agreement. Characteristic curves are presented showing predicted evaporation rate, heat transfer and pressure difference for a set of parameters representative of a high grade vacuum pan near the start of a strike. },
keywords = {Boiling, Calandria Tube, Evaporation, Heat Transfer, Model, Vacuum Pan},
pubstate = {published},
tppubtype = {conference}
}
A heat transfer model of boiling flow in steam heated calandria tubes is presented. The model predictions for vapour formation, heat transfer and pressure difference are compared with experimental data and yield reasonable agreement. Characteristic curves are presented showing predicted evaporation rate, heat transfer and pressure difference for a set of parameters representative of a high grade vacuum pan near the start of a strike. |

Atkinson, Bruce J; Stephens, Darrin W; Harris, Jonathan A; Schneider, Phil A The net pressure driving force due to boiling in calandria tubes. Inproceedings Hogarth, DM (Ed.): Australian Society of Sugar Cane Technologists, 2000. Abstract | Links | BibTeX | Tags: Boiling, Calandria, Evaporation, Flow, Mass Flow Rate, Model, Pressure, Temperature, Thermodynamic, Two-Phase, Vacuum Pan @inproceedings{atkinson2000net,
title = {The net pressure driving force due to boiling in calandria tubes.},
author = {Bruce J Atkinson and Darrin W Stephens and Jonathan A Harris and Phil A Schneider},
editor = {DM Hogarth },
doi = {10.13140/RG.2.1.1998.5762},
year = {2000},
date = {2000-01-01},
booktitle = {Australian Society of Sugar Cane Technologists},
journal = {Proceedings of the 2000 Conference of the Australian Society of Sugar Cane Technologists held at Bundaberg, Queensland, Australia, 2 May to 5 May 2000.},
volume = {22},
abstract = {Vapour formation due to boiling in calandria tubes provides the driving force for natural circulation in vacuums pans. The net pressure difference generated across a calandria tube is determined by the average density deficit in the tube relative to the downcomer (i.e. the amount of vapour in the tube) and the pressure loss due to friction and acceleration. This paper presents a mathematical model of the two-phase flow of molasses and vapour in calandria tube assuming equilibrium thermodynamics and steady state conditions. The model can predict the net pressure driving force and the evaporation rate produced by a tube as a function of parameters such as heat input, mass flow rate, liquid height above the calandria and boiling point elevation. Additionally, the model yields detailed profiles of temperature, absolute pressure, volume fraction and other variables as a function of distance along the calandria tube. Results are presented in the form of characteristic curves representing the net pressure difference available to drive natural circulation as a function of applied heat and mass flow rate. The circulation rate and evaporation rate in natural circulation lop may be determined by matching the appropriate characteristic curve to the system response curve for the loop. An example is presented to illustrate the application of the model.},
keywords = {Boiling, Calandria, Evaporation, Flow, Mass Flow Rate, Model, Pressure, Temperature, Thermodynamic, Two-Phase, Vacuum Pan},
pubstate = {published},
tppubtype = {inproceedings}
}
Vapour formation due to boiling in calandria tubes provides the driving force for natural circulation in vacuums pans. The net pressure difference generated across a calandria tube is determined by the average density deficit in the tube relative to the downcomer (i.e. the amount of vapour in the tube) and the pressure loss due to friction and acceleration. This paper presents a mathematical model of the two-phase flow of molasses and vapour in calandria tube assuming equilibrium thermodynamics and steady state conditions. The model can predict the net pressure driving force and the evaporation rate produced by a tube as a function of parameters such as heat input, mass flow rate, liquid height above the calandria and boiling point elevation. Additionally, the model yields detailed profiles of temperature, absolute pressure, volume fraction and other variables as a function of distance along the calandria tube. Results are presented in the form of characteristic curves representing the net pressure difference available to drive natural circulation as a function of applied heat and mass flow rate. The circulation rate and evaporation rate in natural circulation lop may be determined by matching the appropriate characteristic curve to the system response curve for the loop. An example is presented to illustrate the application of the model. |

Stephens, Darrin W; Harris, Jonathan A Modelling convective boiling of molasses Conference 2nd International Conference on CFD in the Minerals and Processing Industries, CSIRO, Melbourne, Australia, 1999. Abstract | Links | BibTeX | Tags: Boiling, Flow, Heat Transfer, Model, Modelling, ODE, Pressure, Two-Phase @conference{stephens1999modelling,
title = {Modelling convective boiling of molasses},
author = {Darrin W Stephens and Jonathan A Harris},
doi = {10.13140/RG.2.1.2359.0242},
year = {1999},
date = {1999-01-01},
booktitle = {2nd International Conference on CFD in the Minerals and Processing Industries, CSIRO, Melbourne, Australia},
abstract = {One-and two-dimensional numerical models of forced convective boiling of molasses in a calandria tube are described. The flow in the tube is considered to be composed of two phases (molasses and steam). The one-dimensional model solves a simplified set of ODEs describing the non-equilibrium boiling process. The two-dimensional model is based on the Eulerian/Eulerian multi-phase approach as implemented in the CFX-4.2 CFD code, and solves for the distribution of volume fraction and the temperature and velocity of each phase, along with global parameters such as pressure drop and evaporation rate. Solutions are presented for a case with similar conditions to those expected in a batch vacuum pan. The results show that the flow in the tube is complex and multi-dimensional. Vapour forms both at the wall (due to direct heating) as well as in the centre (due to bulk boiling). The observed features of the flow from the numerical simulation are qualitatively similar to available experimental observations made by previous investigators, although quantitative agreement has yet to be achieved.},
keywords = {Boiling, Flow, Heat Transfer, Model, Modelling, ODE, Pressure, Two-Phase},
pubstate = {published},
tppubtype = {conference}
}
One-and two-dimensional numerical models of forced convective boiling of molasses in a calandria tube are described. The flow in the tube is considered to be composed of two phases (molasses and steam). The one-dimensional model solves a simplified set of ODEs describing the non-equilibrium boiling process. The two-dimensional model is based on the Eulerian/Eulerian multi-phase approach as implemented in the CFX-4.2 CFD code, and solves for the distribution of volume fraction and the temperature and velocity of each phase, along with global parameters such as pressure drop and evaporation rate. Solutions are presented for a case with similar conditions to those expected in a batch vacuum pan. The results show that the flow in the tube is complex and multi-dimensional. Vapour forms both at the wall (due to direct heating) as well as in the centre (due to bulk boiling). The observed features of the flow from the numerical simulation are qualitatively similar to available experimental observations made by previous investigators, although quantitative agreement has yet to be achieved. |