low cost cold room.mid-atlantic · pdf filelow cost cold room using coolbot for refrigeration...
TRANSCRIPT
Low Cost Cold Room Using CoolBot for Refrigeration
2012 Mid-Atlantic Fruit & Vegetable ConventionJohn Wilhoit, Extension Specialist
Biosystems & Agricultural Engineering Department University of Kentucky
Room Air Conditioner Unit Used for Refrigeration Advantages
Low cost Easy to install
Disadvantages Coils will freeze up if you attempt to cool below about 60˚ F Makeshift way to overcome this problem (using strip
heaters, a thermostat, and a timer to create a defrost cycle) is cumbersome to rig up and hard to maintain
“CoolBot” control unit overcomes limitations of using air conditioner for refrigeration
Available from Store it Cold, LLC1 for about $300 Prevents freeze up by cycling the compressor on and off
based on sensor readings of room temperature and frost on the cooling coils and by “fooling” the air conditioner’s temperature sensor with a tiny micro-heater
Can cool down to 33˚ F with sufficient capacity air conditioner
Simple digital controls and readout Very simple to install
1Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement and does not imply approval to the exclusion of other suitable products or firms.
Requires certain brands of air conditioners that have plastic temperature sensors (does not work metal temperature sensors)
Use without filter and front grill on the AC unit Insert frost sensor into fins, free AC’s temperature sensor and
attach CoolBot’s micro-heater to it Installation takes only a few minutes
Low cost cold room for using CoolBot
• Constructed from readily available building materials.
•Room measures 8 ft x 10 ft x 8 ft tall, large enough for substantial
walk-in cold storage space, but small enough to fit into many existing
barns or other covered storage spaces.
•Floors, walls, and ceiling constructed using 2 x 6 or 2 x 4 studs and
plywood sheathing inside and out.
•Floors, walls, and ceiling insulated with batt insulation and foam
board to an R-value of 19.
•Since this is a cooler, vapor barriers are to the outside (the hotter
side) of the constructed walls.
Foam board with taped joints forms vapor barrier on the outsideConstructed with skids on the bottom so it can be dragged around, or even lifted with large forklift
“Walk-in” space of 8’x10’x8’ tall cold room
Link to construction plans schematic at:
http://www.bae.uky.edu/ext/Specialty_Crops/plans.htm
Link to materials and price list at:
http://www.bae.uky.edu/ext/Specialty_Crops/
Additional considerations for low cost cold storage room construction
Floor drain Floor insulation Alternative to batt insulation Alternative materials or structures Low-cost methods for forced-air cooling to
remove field heat
Concrete Floor
Cold Room
< 55˚F
= 55˚F
Ground (soil)
Concrete Floor
Cold Room
>55˚F
Ground (soil)
= 55˚F
Floor Insulation important for improved efficiency if cooler used for very cold temperatures
Foam board instead of batt insulation
Disadvantages of batt insulation Loses much of its insulating value if it gets wetCan harbor mold if it gets wet
Foam board as alternative to batt insulationR-value of 5 per inch thickness 4 inch thickness would not fit within 2x4 stud
walls Estimated additional cost of $500-600 for
equivalent insulating value of batt insulation used in this cold room
Low cost cold room can be made from recycled materials such as these insulated panels.Manufacturers (such as that make garage door panels) sometimes have scraps available at very low cost.
Different fruit and vegetables have different temperature requirements for storage For market growers, many items like squash,
cucumbers, peppers & watermelon do best at 45-60 ˚F.
Tomatoes subject to chilling injury if stored too cold (< 50 ˚F).
Different fruits and vegetables also have different humidity requirements. Best to oversize AC unit if higher humidity is needed.
HortFact-7002, “Recommended Storage Conditions for Vegetables” available at: www.uky.edu/Ag/Horticulture/comveggie.html
http://www.uky.edu/Ag/Horticulture/HortFact7002.pdf
Old or defunct cold storage structures can be refurbished at very low cost using the CoolBot for refrigeration.
NC State extension publication available at:
http:// www.bae.ncsu.edu/programs/extension/publicat/postharv/ag-414-7/index.html