The Phi-Factor
When it comes to safety, getting the right answers is a must. A second point to consider on calorimeters is the Phi-Factor.
In an exothermic reaction, a proportion of the energy released is absorbed by the test cell in which the test is performed – this is expressed in terms of the Phi-Factor. In a test in which the phi-factor is high, means a large amount of heat is lost to the test cell and this effectively slows down the temperature rise rate and reduces the final temperature. In a test allowing low phi-factor conditions, virtually all the energy of the reaction is retained in the sample, which is closer to the conditions of large scale plant and hence represents data that is ideal for scale-up simulation.
Phi-TEC II can be run under both low and high phi-factor conditions, depending on the application.
Only a low-phi factor calorimeter such as the Phi-TEC II can deliver the accurate, scalable safety vital for transferring processes from the lab to pilot or plant scale. For example, this low thermal inertia will enable vent sizing under runway conditions including situations where two-phase venting is involved.
Testing
The system will allow tests that might otherwise be performed in TSu & Phi-TEC I -type devices. Key data produced includes
- So-called “Onset” Temperatures for exotherms
- Runaway data, such as rates of pressure and temperature rise
- Enthalpy of reaction
- Reaction kinetics
Applications of the data include:
- Determination of Venting behaviour (Gassy, tempered, hybrid)
- Determination of Flow Regime (Two-phase or single-phase)
- Kinetic data (eg for TMR, or TNR calculations)
- Safe transport and storage prediction