Experimental and numerical analysis of the thermofluiddynamics in a high-pressure autoclave.

摘要

A medium-sized high hydrostatic pressure autoclave was assessed on the basis of the thermofluiddynamics within it. Temp. measurements conducted simultaneously at various sites within the chamber were used for this assessment, and compared with results from a numerical simulation. Process uniformity was then assessed for various fluids and heat transfer conditions. During treatment of water at 300 or 500 MPa (820 s pressure holding phase), experimental temp. measurements were found to agree well with those simulated numerically. The autoclave was then used to inactivate alpha-amylase from Bacillus subtilis (15g/l Tris-HCl buffer (pH 8.6, 0.01M)), a representative high pressure process. Thermal insulation of the inner wall was found to maximize process uniformity and effectively reduce the duration of the process. Duration was found to decrease by 40% when the activity retention of the non-zero heat transfer process was used as a target value. Use of highly viscous fluids increased non-uniformity, but results suggest that steps to ensure non-zero heat transfer would improve this parameter. It is concluded that thermal insulation of the inner wall of the high pressure autoclave chamber is central to the improvement of process uniformity and cycle efficiency.