Modeling Phase Change Heat Transfer of Liquid/Vapor Systems in Free and Porous Media

2015 ◽  
Author(s):  
James A. Wilson ◽  
Jonathan D. Wehking ◽  
Mark Trautman ◽  
Mark E. Blue ◽  
Ranganathan Kumar
Keyword(s):  
Porous Media ◽  
Phase Change ◽  
Penetration Depth ◽  
Numerical Study ◽  
Porous Matrix ◽  
Thermal Processes ◽  
Liquid Penetration ◽  
Rf Heating ◽  
Phase Change Heat Transfer ◽  
Liquid Vapor

Effective Solvent Extraction Incorporating Electromagnetic Heating (ESEIEH) is a relatively new concept that relies on Radio Frequency (RF) heating and solvents to replace steam in current thermal processes for the purpose of extracting bitumen from oil rich sands. The work presented here will further the understanding of the near wellbore flow and phase behavior of the ESEIEH process in order to better predict solvent vaporization dynamics and heat rates delivered to the pay zone. This numerical study details the aspects of phase change of liquid/vapor systems confined in porous media heated by electromagnetic radiation, and approximated by a volumetric heat source term in the energy equation. The objective of this work is to utilize the numerical methodology presented herein to predict liquid penetration depth in a heated isotropic porous matrix to avoid the over-saturation of liquid solvent in the pay zone. Results demonstrate the sensitivity of the liquid solvent penetration depth to the solvent delivery rate and the resulting temperature.

Three-Dimensional Numerical Study on Freezing Phase Change Heat Transfer in Biological Tissue Embedded With Two Cryoprobes

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Fang Zhao ◽  
Zhenqian Chen
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Biological Tissue ◽  
Clinical Medicine ◽  
Numerical Study ◽  
Biological Tissues ◽  
Freezing Process ◽  
Ice Crystal ◽  
Obvious Effect ◽  
Phase Change Heat Transfer

Biological tissues undergo complex phase change heat transfer processes during cryosurgery, and a theoretical model is preferable to forecast this heat experience. A mathematical model for phase change heat transfer in cryosurgery was established. In this model, a fractal treelike branched network was used to describe the complicated geometrical frame of blood vessels. The temperature distribution and ice crystal growth process in biological tissue including normal tissue and tumor embedded with two cryoprobes were numerically simulated. The effects of cooling rate, initial temperature, and distance of two cryoprobes on freezing process of tissue were also studied. The results show that the ice crystal grows more rapidly in the initial freezing stage (<600 s) and then slows down in the following process, and the precooling of cryoprobes has no obvious effect on freezing rate of tissue. It also can be seen that the distance of 10 mm between two cryoprobes produces an optimal freezing effect for the tumor size (20 mm × 10 mm) in the present study compared with the distances of 6 mm and 14 mm. The numerical results are significant in providing technical reference for application of cryosurgery in clinical medicine.

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