Momentum can be a cause of dissatisfactory results in the semi - shut greenhouse . So what is it , and how can it be forestall ? Godfrey Dol , an expert on mature in semi - closed glasshouses , shares his experiences .
Figure 1 below shows a bird’s - eye formal view of a semi - unopen glasshouse .
Figure 1 Airflows in a semi - closed glasshouse top view .
On the left helping hand side is the climate chamber with the chill domiciliation bulwark on the far odd . The puritanical lines depict the ducts or lay - flats through which the fans distribute the melody into the glasshouse . On the far right wing is the concrete walkway which is usually a central nerve tract with another compartment on the other side .
The rooter blow the aviation into the nursery from left to right field . The air leaving the ducts does not move vertical to the duct . rather , the direction is slightly to the right field , off from the climate bedchamber , as depicted by the small blue arrows in the diagram . This produce an aviation drift in the way of the way the fan are boast . In this shell , the air moves from leave to right hand . It is common to use an interior hose inside the tube to minimise this effect . However , it does not completely contradict the problem .
image 2 Momentum : Unwanted airflow in the nursery . In figure 2 above , a side scene is depict . The blue pointer at the bottom ( 1 ) shows the air current resulting from the air give the air hose under a slight angle . This is an unwelcome movement as it touch the upwards air movement of the stale air , which is the way the line is designed to move .
The gentle wind progresses as a result from the sideways melody motility . Once it arrive at the central nerve pathway , there is no flora canopy pushing the stream down along at priming level . As a result , the air rises ( 2 ) . Once above the crop , the air starts move in the opposite direction ( 3).The air heats up while trip along the upper part of the glasshouse ( 4 ) . Once the air arrives back at the climate chamber , the blistering air is sucked down by the scurvy pressure create by the air movingaway from the mood chamber at land level ( 5 ) . The temperature of the zephyr being fellate down can be more than 50 degrees Celsius , which causes real damage to the plant . At 60 % fan speed theair being soak up down is confined to a pocket-size orbit near the climate bedroom . At increasing fan fastness the region expands further into the glasshouse ( 6 )
Crops such as Truss on the Vine ( ToV ) and beefsteak tomatoes are particularly affected by the warm air flow because they do not respond well to warm temperature .
He balloonGenerally , reducing the fan speed , to the extent that 8 gentle wind - exchanges per hour are realised , reduce momentum . The stream of the zephyr is very blue-blooded and is difficult to visualise with smoke ( too heavy ) orsoap bubbles ( too brusque life duo ) . The best method acting to visualise momentum is by weigh down a He balloon to near weightlessness ( video ) .
The video shows impulse is veridical . It shows a helium balloon move aside from the climate chamber at priming coat point . As the balloon move up it is picked up by the strain current in the top of the glasshouse , going into the paired management .
The sucking down of the hot air is much hard to figure but it is the only legitimate way the air can march on . It is often hint that the recirculation window can be used to allow the negative pressure in the climate sleeping accommodation to remove the hot air building up against the clime bedchamber .
This never fixes the job totally . When temperatures outdoors are high , all the air needs to be cool through the pad wall . Opening the recirculation windowpane allows the hot air to move into the climate chamber and warm up the air being blown into the glasshouse . The book of line that is being cooled is reduced . The fans must run faster to keep the glasshouse cool , which in turn worsens the job . Under these experimental condition , it is always better to leave the recirculation window close and decoct the sports fan velocity to avoid the upshot of impulse . ( other ways to keep the semi - closed glasshouse coolcan be found here)At cool outside temperature it is reliable that some of the hot air can be hit through the climate sleeping room , but in that position , it is good to reduce the fan speed and avoid the problem totally .
Figure 3 Poor Pollination ( Courtesy Andrew McIlwain )
Figure 3 shows distinctive pollination issues that can rise from the warm air heating up plant life . The first two yield did not congeal properly , which is typical of damage incurred through momentum . It causes major production loss . The terms will carry itself first near the clime bedchamber where the raging air is sucked down . Increasing the devotee pep pill will ensue in the area affect becoming prominent .
Technical solutions to the impulse problem are being solve on , but for now reducing devotee speed is the best and comfortable way to avoid or minimise momentum , according to Godrey .
This article is part of a series about grow in a semi - closed glasshouse . scan here - go’sfor semi - closed greenhouse , coolingandthe difference between semi - closed and pad and fan glasshouse .
For more information : nursery Consultancywww.glasshouse-consultancy.com
Godfrey DolLinkedIn[email protected]+81 80 700 94 006
