Food Engineering Practice Test 4

1. The existence of a thick constant film between two phases is a proposal by which of the following theories?

2. Drying rate curve is plot between _____ and _____

3. Sherwood number is _____

4. Statement 1: Penetration theory states that mass transfer coefficient is directly proportional to diffusivity coefficient which was later proved wrong.
Statement 2: Penetration theory states that mass transfer is based on unsteady mass transfer.

5. Which of the following denotes gas phase mass transfer coefficient?

6. Statement 1: Forward feeding requires pumps for the feed at every step.
Statement 2: In a backward feeding arrangement, the most concentrated feed is exposed to the maximum steam in order to remove heat. This is its advantage.

7. Statement 1: Diffusion of gas component through the resistive film to the bulk of the liquid is the rate determining step.
Statement 2: Diffusion of gas component through the gas-liquid inter-phase is the rate determining step.

8. Tunnel dryer is only a continuous version of a cabinet tray dryer.

9. Statement 1: Difference between 1-1 and 1-2 heat exchanger is that 1-2 has both counter AND co current, whereas 1-1 has only co-current.
Statement 2: 1-2 heat exchanger requires a high pressure drop.

10. Although microwave heating can be used for drying of food containing uneven water content, it is isn’t done for certain food products like garlic. Why?