Characterization of heat transfer of large orbitally shaken cylindrical bioreactors

• Cylindrical shaken disposable bioreactors of volume 20 and 50 L are characterized with respect to heat transfer from liquid inside the vessel to the surrounding atmosphere.
• Overall heat transfer coefficient is obtained for different operating conditions with and without lateral air flow for water and glycerol/water system.
• Rate limiting steps for overall heat transfer process are identified.
• An empirical model is proposed to calculate overall heat transfer coefficient.

Disposable shaking bioreactors are a promising alternative to other disposable bioreactors owing to their ease of operation, flexibility, defined hydrodynamics and characterization. Shaken bioreactors of sizes 20 L and 50 L are characterized in terms of heat transfer characteristics in this research work. Water and an 80% glycerol–water system were used as fluid. Results indicated large heat generation due to shake mixing which was observed by temperature difference between the fluid inside the vessel and the surrounding air outside the vessel. Maximum temperature difference of ca. 30 K was encountered for a 50 L vessel, at 300 rpm and 20 L filling volume. Outside heat transfer rate was governing the overall heat transfer process. Lateral air flow did increase heat transfer rates to large extent. An empirical correlation of overall heat transfer coefficient was obtained in terms of filling volume, rotational speed and lateral air flow rate. However, as the vessel thickness increased, the overall heat transfer process was limited by vessel wall resistance.