Heat Flashcards
(11 cards)
What does ‘ideally isothermal’ mean in the context of a CSTR?
It means the temperature should remain constant during operation, but in reality, it often changes (polytropic behavior).
Why is precise temperature control important in a CSTR?
It prevents side reactions, protects cell viability, and ensures consistent reaction rates and product stability.
What are the three main modes of heat transport in a CSTR?
Convection, conduction, and radiation.
What mechanical component in a CSTR can contribute to heat generation?
The agitator, which can convert mechanical energy into heat.
Name the four main components of the heat balance equation in a CSTR.
Heat in via inflow (Q0), heat out via outflow (Qa), heat from reaction (QR), and heat exchanged via wall (Qw).
What is the condition for steady-state heat balance in a CSTR?
The total heat change over time (dQ/dt) must be zero.
How can temperature be controlled in a CSTR?
By adjusting the temperature and flow rate of the inflow/outflow or using a heating/cooling system like a jacket.
What does adiabatic operation mean in a CSTR?
No heat is exchanged with the surroundings; temperature changes are only due to the reaction and flow.
What equation describes the adiabatic temperature in a CSTR?
Ta = T0 + ΔTad * Xa, where Ta is the actual temperature, T0 is the feed temperature, ΔTad is the adiabatic temp rise, and Xa is the conversion.
How does conversion affect temperature in adiabatic operation?
As conversion increases, temperature also increases, often in an S-shaped curve.
What risk is associated with high starting temperature (T0) in a CSTR?
It may lead to instability or shift to an undesired operating point due to multiple steady states.
