6/5/ Initial Cooling Chapter and Commercial Cooling of Fruits, Vegetables and Flowers Cooling Begins in the Field Prevent heating in the field. Shorten time before cooling begins. Jim Thompson Biological & Agricultural Engineering, UC Davis Shade product to reduce heat gain & moisture loss Carrot Receiving water spray Use frequent, scheduled pick up Transport Cooling Product temperature drop is rare in trailers. 5 6
6/5/ Vertical Airflow Slow cooling in marine transport 7 8 Marine Container Stack to ceiling product Prevent air from bypassing the load Cover floor Stack to ceiling at the rear of the load cfm per ton of product. Ceiling fans
6/5/ cfm per ton of product. Space stack product. -6 between lanes cfm per ton of product. Space stack product. Well vented boxes. Sloped sides Vents 5 6 Highest Freezing Temperature cfm per ton of product. Space stack product. Well vented boxes. owest possible air temperature. 7 C F Apples -.5 9. Cherries -. 8.8 Pear -.7 9. Asparagus -.6.9 ettuce -..7 Cauliflower -.8.6 8
6/5/ Pallets of tight fill plums in corrugated boxes Vents Box spacing Stacking ongest cooling time (hr) none none cross 8 % none register % register 8 Half Cooling Time in Days for palletized d Anjou Pears Wrapped Tray packed ocation outside inside outside inside top..9.7. middle 7. 5..6 7. bottom...8. 9 Kader & Fabion Forced Air Cooling Forced Air - Tunnel Pallets of tight fill plums in corrugated boxes Vents Box spacing Stacking ongest cooling time (hr) % none register - 6 Tarp Exhaust fan
6/5/ Reversing Airflow Direction closed open closed open 5 6 Portable Fan & Tarp Small Scale Forced Air 7 8 Airflow Forced Air - Serpentine Cloth strips 9 5
6/5/ Operating serpentine cooler Gravity operated louver Seal Fan Forced Air - Cold Wall Evaporator Damper Forced Air Cooling / / 7/8 5/6 Cool Temperature ( F) 9 Peaches at.5 cfm/lb. 8 7 6 most shielded 5 mass average most exposed..... 5. Hours of Cooling 5 6 Temperature ( C) 6
6/5/ Forced Air Cooling 7/8 Cooling Time (hr) 5 Cantaloupe, dia.=6. Peaches, dia.=.5" Cherries, dia.=." Air Flow Rate (cfm/lb or l/s-kg) 7 High Capacity Cooling High airflow rate (strawberries in <6 min) Airflow reversal Modular Energy efficient 7/8 Cooling Time (hr) Peaches Cherries Air Flow Rate (cfm/lb) MACS - Semi-continuous Flow www.macscooler.com Conveyor American Cooling - Field-side Cooler Refrigeration trailer Forced air cooler w/ flow reversal Bobtail reefer truck Generator Refrigerated dock Airflow reverses Inside cold room Enclosed outfeed conveyor American Cooling - Fieldside Cooler Vertical Airflow Cooler http://ne-postharvest.com 7
6/5/ Pressure Drop vs. Airflow Venting Pressure Drop (in.) Pear Grape Air Flow (cfm/lb) Poor Good - 5% Box Venting Bagged Grapes 5 6 Moisture oss in Forced Air Cooling Fiberboard Strength Weight loss at 8% cool (%).5..5 Carrots without tops 5 5 5 F Temperature drop during cooling C 7 Retained Strength (%) strength 5 5 moisture 6 8 Relative Humidity (%) Moisture Content (%) 8 8
6/5/ Electricity Use in Forced Air Cooling Electricity Use vs. Throughput Electricity Use (%) Product 6 Fans ights 6 Walls ifts 9 Energy Coeficient....8.6.. y =.8x +.8 R =.996. 6 8 6 5 Hydrocooling 5 5 Immersion Hydrocooler Immersion tank Evaporator Water circulation 5 5 9
6/5/ 7/8ths Cooling Time (min) 8 6 Hydrocooling Time carrot packed corn with husk potato tomato peach citrus apple cantaloupe cantaloupe Cherry Hydrocooling Temperature ( C) 5 5 5 7 GPM/ft^ 5 GPM/ft^ radish asparagus 5 Product diameter (inches) 55 5 5 Time (min) 56 Moisture oss in Hydrocooling Water Beating Damage Gain.5 % to lose.5% 57 58 Control ph and Chlorine evels Package Icing 59 6
6/5/ iquid Ice Machine Ice solidifies & melts away from product 6 6 Manual iquid Icing Iced Boxes at Market 6 6 Small Ice Machine Vacuum Cooling At 5mm Hg water boils at C 65 66
6/5/ Pallet Vacuum Cooler Cools product that can release moisture quickly 67 68 Moisture oss in Vacuum Cooling Water Spray Vacuum Cooling ose. to. % %moisture loss for each F (6 C) of temperature drop 69 7 Cold Rooms Selecting a Cooling System Product requirements. Product mix. Temperature requirements. Cooler cost. 7 7
6/5/ Capital Cost Energy Use Cost ($/lb-day) iquid ice Vacuum Forced air Hydro 7 Energy Coefficient Vacuum Hydro Hydro Vac iquid ice Forced air 7