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Determining Maximum Sublimation Rate for a Production Lyophilizer: Computational Modeling and Comparison With Ice
Vaibhav Kshirsagar1, Serguei Tchessalov2, Frank Kanka3
1School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907.
Journal of Pharmaceutical Sciences
|November 12, 2018
Summary
Computational fluid dynamics modeling accurately predicts freeze dryer equipment capability limits. This approach speeds up scale-up for lyophilized pharmaceuticals by identifying turbulent flow effects and minimum controllable pressure.
Area of Science:
- Pharmaceutical Engineering
- Chemical Engineering
- Fluid Dynamics
Background:
- Equipment capability is crucial for scaling up and technology transfer of lyophilized pharmaceutical products.
- Experimental determination of equipment limits is time-consuming for production freeze dryers.
- Understanding these limits is essential for optimizing lyophilization processes.
Purpose of the Study:
- To present computational fluid dynamics (CFD) modeling for freeze dryer equipment capability.
- To compare CFD predictions with experimental data for minimum controllable pressure.
- To investigate the impact of turbulent effects on lyophilizer performance.
Main Methods:
- Computational fluid dynamics (CFD) modeling of vapor flow in a 23 m² shelf area freeze dryer.
- Experimental ice slab sublimation tests to determine minimum controllable pressure.
- Comparison of CFD results with experimental data under various operating conditions.
Main Results:
- CFD modeling accurately predicted minimum controllable pressure within 5% of experimental data.
- Turbulent flow effects were identified at sublimation rates above 17 kg/h.
- Turbulence increased minimum controllable pressure by 3-4 mTorr for flow rates up to 40 kg/h.
- The impact of equipment geometry variations and condenser load on pressure control was analyzed.
Conclusions:
- CFD modeling is a reliable and efficient tool for assessing freeze dryer equipment capability.
- Understanding turbulence onset is key to controlling pressure and ensuring product quality during lyophilization.
- The study provides valuable insights for optimizing freeze dryer design and operation for pharmaceutical applications.
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