supplemental cooling

Question 1

why cooling?

Answer 1

taste, consistancy, hygiene

Question 2

what temp best for bacteria growth, best temp for fridge

Answer 2

growth: 5 - 75 C
fridge: 3 - 5

Question 3

why is bacteria bad on food?

Answer 3

not necessarily bad to have bacteria but it incrases probability of bad

Question 4

cooling regulation

Answer 4

not by FAR
local country food regulations
4deg C has become european accepted standard

Question 5

cooling progression

Answer 5

• no importance
• dry ice
• air chiller
• remote chiller system
• supp cooling system

Question 6

what is basic principle of dry ice?

Answer 6

solid to gas (sublime) at low temp

-> fxn as evaporator

Question 7

disadvantages dry ice

Answer 7

no temp control
-finite supply
supply variable

Question 8

how to calculate heat leaving via condenser (or by dry Ice

Answer 8

Qdot = mdot (deltah) = U * A * deltaT

Question 9

disadvantages of loop coolign (primary loop) (commonly used)

Answer 9

• difficult to reach exact temp (can get freezing)
• takes large space -> difficult for flexibility
• heat load remains inside pressurized cabin increased demand on ac system

Question 10

system requirements

Answer 10

• redundency (each 70%, redundant pump, double duct work)
• primarily for food and avionics
• no extra heat to cabin
• range of cooling for food
• ACUs in GAC with own interface
• sufficient communication (use CAN buses)
• easy servicing (in belly fairing)

Question 11

what makes god coolant?

Answer 11

non-toxic -non flammable, non-corrosive, will evaporate if leakage, high specific heat
-low density