ENERGY SAVINGS Energy savings with fans
This article looks at fans in mushroom growing rooms. Indicative fan speeds, air volume and air speeds on both manual and mechanical harves- ting farms at various stages of cultivation will be discussed. Stealthy energy users like fans where resistance causes unnecessary power consumption
(e.g. soiled filters or coils) are also discussed. By Jan Gielen, manager Delphy Mushrooms Specialist Climate & Energy
j.gielen@
delphy.nl
Fan speeds, air volumes and airspeeds
The important factor when extracting evaporated moisture from growing rooms is the volume of air. On manual harvesting farms, a fan capacity of 22.5 m3
/h per m2 growing surface area can be
taken as a guideline (on mechanical harvesting farms this is 25 m3 surface area).
/h per m2 growing
The table below shows indicative values for manual and mechanical harvesting farms for optimally dimensioned installations, as well as the air volume, fan speeds and air speed exiting the duct openings. In practice, this pattern naturally varies widely, so these values should be used as an indication only. When frequency controllers are used (as indicated in the tables), there is a reasonable linear correlation between the fan speed and air volume. (This is, however, not the case with transformer controls!).
The table also shows that in less optimally dimensioned installations, the fan speed or speed of air exiting the openings does not automatically
Centrifugal fan (direct drive) with frequency controller.
mean the correct air volume is achieved. Example: air exiting the ducting at high speed does not automatically mean that enough air is entering the growing room. In a reverse situation, air exiting the ducting at low speed does not automatically mean too little air is provided. The actual design of the air ducts largely dictates the speed of air blown into a growing room, indepen- dent to the air volume actually provided. Like- wise, a fan speed set to a certain position does not automatically imply the correct volume of air is
Manual harvest (indication) Air volume m3 Maximum
Mycelium start Pinheading Outgrow
22.5 15.8 9
12.4
/h/m2
Fan speed % Air speed
100 70 40 55
openings m/s 8.5 6.0 3.4 4.7
Mechanical harvest (indication) Air volume m3/h/m2 Fan speed % Air speed Maximum
Mycelium start Pinheading Outgrow
42 MUSHROOM BUSINESS 25
20.0 11.3 16.3
100 80 45 65
openings m/s 9.5 7.6 4.3 6.2
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