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VIII. AIR CIRCULATION

VIII. AIR CIRCULATION. Definition - movement of air within greenhouse. Circulation importance 1. Uniform air movement 2. Prevent temperature layering. Leaf. CO 2. H 2 O. 3. better air exchange around plant a. replace CO 2 depleted air b. remove high humidity

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VIII. AIR CIRCULATION

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  1. VIII. AIR CIRCULATION • Definition - movement of air within greenhouse

  2. Circulation importance • 1. Uniform air movement • 2. Prevent temperature layering

  3. Leaf CO2 H2O 3. better air exchange around plant a. replace CO2 depleted air b. remove high humidity c. reduce temperature of leaf surfaces Heat

  4. C.Circulation requirements • 40 ft/min minimum up to 100 ft/min • Slight movement of leaf

  5. High Low Circulation: Photosynthesis vs rate of air movement around leaves High turbulence Low turbulence

  6. D.When to Circulate • When • Night: • continuous all year • Day: • winter • only when min. ventilation off • during medium or • max ventilation • summer - usually off

  7. E. Problems • Uniform air movement • Moving air through plants

  8. Types of Systems 1. Horizontal Air Flow (HAF) a. Description b. Requirements • Fan capacity: 1/4 vol. • Placement: • 25' x 100' four fans • 20’ x 50’ two fans c. Better than poly tube

  9. Circulation: HAF HAF

  10. 2. Plastic (poly) tube system a. Description b. Requirements • fan capacity = 1/4 house volume • cross sectional area of tube = 1 sq ft/100 cuft/min, capacity of fan • total area of all holes = 1.5 to 2 times cross sectional area • 30' wide house: two fans • 100-150' long: two fans

  11. Circulation: Polytube- minimum ventilation and heating

  12. Circulation: Polytube

  13. Circulation: Polytube air

  14. Polytube circulation

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