Refrigeration

Question 1

Temperature maintenance system

Answer 1

To store chilled or frozen
Must have sufficient space to remove heat from walls, humans door openings
Low air velocity
Similar temperature to food

Question 2

Temperature reduction system

Answer 2

To chill food
Large difference between food and air
Large space for heat conduction

Question 3

Chilling definition

Answer 3

A process by which hold temperature is reduced to just below freezing point of food -1 to. 8 degrees

Question 4

Factors affecting cooling rate

Answer 4

Surface area
Coefficient of heat transfer
Quantity of food
Temperature of air vs temp of food

Question 5

Evaporator

Answer 5

Cool liquid cools heat from air in fridge

Question 6

Compressor

Answer 6

Vapour is compressed bringing it to a higher pressure

Question 7

Condenser

Answer 7

Gas is condensed into a cool liquid and heat is removed through ventilation fins

Question 8

Expansion valve

Answer 8

Flow of liquid is controlled and pressure is lowered to return Vapour to liquid

Question 9

Changes during freezing g

Answer 9

Formation of ice crystals
Volume changes - ice has bigger volume so expands food
Solute concentration changes - less water due to crystals so solutes are stronger

Question 10

Freezing point of food

Answer 10

Temperature at which minute ice crystals are held in equilibrium with surrounding water

Question 11

Eutectic temperature

Answer 11

Temp at which a crystal of individual solute existes in equilibrium with unfrozen liquor and ice