Lecture 8: Cold Storage Systems Flashcards
(43 cards)
what components must be controlled in a storage system?
temp RH air velocity air composition insulation refrigeration capacity
simple systems are used for what?
ventilated storages (for potato, carrot, dry onion)
what do simple systems take into account?
insulation
air circulation
ventilation
simple systems uses what atmosphere storage?
RA storage = regular atmosphere storage
what needs to be taken into account for complex systems?
insulation air tightness vapor barrier price control of temp RH air comp
what are examples of complex systems?
CA storage
hypobaric storage
separate storage chambers for each produce is ideal but not practical. What is more common instead? What must be taken into account?
- mixed loads
- compatibility of temp, ethylene, RH, odor
what should be used to estimate quality loss?
Q10 concept
temp fluctuations should be what?
why?
low +/- 2C
b/c large fluctuations means a loss of quality
warm produce coming in contact with cold air results in what?
- dessication, if air is not saturated
- produce sweating, if air is saturated
warm air coming in contact with cold produce results in what?
- dessication if WVPD is positive
- condensation if WVPD is negative
adequate refrigeration capacity should be able to handle ____ and ___ loads
normal and unexpected loads
how can storage life of incoming commodities be maximized?
by precooling incoming produce to storage temp
storage life of all commodities will be at risk when….?
warm products are brought in. This causes large temp fluctuations and product warming
if the refrigeration capacity is undersized, what occurs?
- slow cooling
- product warming
- large temp fluctuations = larger quality loss
why should refrigeration capacity not be oversized?
more expensive
refrigeration temp should be close to _____
why?
room temp
what kind of cooling surface area of cooling coils is best?
larger surface area = more efficient heat transfer
what can be used to increase surface area?
fins
why is good air velocity important?
for proper temp distribution
at high flow rate, dessication occurs
at low flow rates, improper cooling occurs
thus, moderate rate is the best
why is adequate thermal insulation imp?
prevents heat gain from walls, doors, floor, etc…
how can moisture loss be reduced?
- having a smaller temp diff between coil and air
- smaller temp fluctuation
- humidifying air externally using special technique for storage: jacketed storage, filacell storage, fog spray system
describe the jacketed storage system
conserves moisture to better deal with high RH
describe the filacell storage system
humidifies air leaving cooling coil