5 Cooling Methods Flashcards
what are 6 commercial cooling methods?
- room cooling
- forced air cooling
- hydrocooling
- package-icing
- vacuum cooling
- transit cooling
describe room cooling
- simple
- produce cooled in refrigerated room
- cold air discharged from ceiling sweeps
- heat from produce is brought to cooling coils
pros and cons of room cooling?
pros:
- consolidated cooling and storage
- decreased handling
- simple design
- suitable for moderate loads
cons:
- slow cooling
- desiccation when air speeds too high
- slower air speeds prolong cooling
name some special considerations for room cooling (if you can name like 4 out 8 i’ll be happy)
- need efficient storage maintainence
- proper stacking to allow air to pass around the container
- pallet frames for systematic loading
- clear fork lift openings for air flow
- container ventilation for air to contact the produce
- good air speed to create turbulence
- eliminate empty spaces in room
- false walls can be used to divert air from empty spaces
you see a modified room cooling technique in which there are cones on the ceiling. what are those cones?
ceiling jets - they concentrate cool air into stack rather than over it
you see a modified room cooling technique in which the large room appears to be separated into several smaller sections. what are these sections called?
cooling bays - enables more specialized control for different varieties of produce
describe forced air cooling
high velocity air is forced through the container
what are the alternate names for forced air cooling?
pressure or suction cooling
compare forced air cooling to room cooling
forced air is more efficient - it removes heat faster.
describe the air flow in forced air cooling
negative pressure is created between the fan and container by appropriate stacking and blocking of open spaces. this causes suction of cold air from room through package vents.
describe hydrocooling
cold water is used to remove heat
what are the pros and cons of hydrocooling?
pros:
- no moisture loss/desiccation
- water is a more efficient medium than air
cons:
- water must be cleaned
- packages/produce must be water tolerant
- cooled product must be moved quickly to a cold room
describe transit cooling
inside the truck: usually uses one of 4 methods: mechanical refrigeration, top icing, evaporation of liquid nitrogen (dry ice), or a combo of theesse
use of liquid nitrogen or solid CO2 is considered _____ cooling
cryogenic
what’s the incentive for using liquid nitrogen?
- commercially available
- environmentally friendly
- minimal equipment required
what is the incentive for using solid CO2?
- can desirably add CO2 to room
what is the incentive for using package icing?
- results in fast cooling
- provides high RH
what are some cons to using package icing?
- must accommodate for water from ice packs
- packages should be water tolerant
describe vacuum cooling
decreasing pressure decreases the temperature at which water vaporizes; latent heat is removed faster
what are the basic components of a vacuum cooler?
- vacuum chamber: a cylindrical vessel. it’s leak-proof and can withstand at least 1 atm
- vacuum device: mechanical or steam injection
- condenser: water or refrigeration coils
what factors influence vacuum cooling?
- surface area
- porosity
- degree of vacuum
- availability of water
what factors influence your choice of cooling method?
- nature of produce
- compatibility with existing facilities
- initial capital investment cost, operation, cost, labor cost & maintenance cost
- harvesting in coolest part of the day
- keeping delays short
- parking in the shade
