Transport Phenomena in Bioscience Engeneering
6 juni 2021
Theory:
Oxygen transport in an apple:
- Derive the governing equation for steady state O2 diffusion in apple with a uniform and constant O2 consumption rate.
- Solve for infinitely small transport resistance at the surface of the fruit.
- Generalise equation for a surface mass transfer boundary condition.
Exercise: Complex pump + cooling pipe system to solve. In pipes coolant to cool the beer in the cylinder. One pump in the system. a. Calculate flow in the pipe. b. Check if the given flow is enough to cool down the beer.
Small questions:
- Green beans are osmotically dried by putting them in a highly concentrated salt solution that is at rest. The density of a bean is approximately equal to that of the solution. Also the bean is oriented horizontally. Calculate hm (via Sh, Ra, Gr)
- In winter the temperature is higher on a cloudy day than when the sky is open, how come? (λmax*T= 2897.6 µm K λsun = cste/5800 K en λearth = cste/300 K. Uit de grafiek halen we dat door de wolken we zien dat λsun niet gebsorbeerd, maar λearth wel geabsorbeerd wordt. Een deel van de geabsorbeerde energie wordt terug uitgezonden.)
- CO2 is used in soda (hier Coca Cola) to add sizzle and fizz. It reaches an equilibrium: CO2(gas) → CO2(liq) → H2CO3 → H+ + HCO3-
- Why not use O2? (zuurstof vormt geen bicarbonaat, er kan minder opgeslagen worden)
- What happens when you open the bottle? (Henry’s wet)
- Does fizz depend on temperature? (Ja, de H van Henry zie ook gegeven grafiek)
- What happens if you add strong acid? (reactie wordt naar links gedreven)
- How far can a corona virus particle (d=100 nm) travel on average in a room at still air with room temperature during one hour? (t=x2/2Dab, waarbij Dab=κ*T/6πµr)# What’s drip loss and how can you reduce it? (Ondercooling van intercellulair fluidum en cytoplasma leidt tot osmotische dehydratie. Bij smelten wordt daardoor ‘meer water dan normaal’ verloren. Het wordt gereduceerd door absorberende verpakking)