GB2184828A - Air circulation in a building - Google Patents

Abstract

An air circulation arrangement for a space within a building, e.g. an animal rearing house, includes a fan F to draw air upwards in the space and discharge it horizontally into the space so that at the edges of the space the air is deflected downwards to circulate within the space. The flow velocity may be of the order of 5 m/s and the fan may be of axial, centrifugal, tangential or mixed flow type. <IMAGE>

Description

SPECIFICATION Air circulation in a building This invention relates to the circulation of air in buildings. The invention has particular value for animal rearing houses such as "broiler" houses.

The circulation of air in building, especially in a space such as a workshop which has a large volume and generally a high ceiling, can improve the effectiveness of heating by returning warmer air towards the ground from higher levels, i.e. those well above head height.

As described in UK Patent Application 8221635 the efficient rearing of animals at a reasonable cost requires careful attention to the use of energy for heating and air circulation, including ventilation. For many reasons, e.g. construction cost and efficient heating action, rearing houses with minimum roof space are preferred. However, the accepted air circulation improvement techniques are based on fans with long horizontally placed blades, known as "punka" fans, which revolve relatively slowly to drive warm air down from the large roof space above head height, i.e. above about 7' from the ground. Such techniques do not necessarily distribute the air efficiently and can cause dust to be raised at floor level and draught due to excessive total air movements if the speed of air driven down by the fan is raised to improve circulation rate.

It is an object of the invention to provide an improved arrangement and method of air circulation, useful for buildings and particularly for animal rearing houses.

According to the invention there is provided an air circulation arrangement for a space within a building including means to draw air upwards in the space and discharge it within the space substantially horizontally and outwardly towards the edges of the space for downward deflection to circulate within the space.

According to a particular aspect of the invention there is provided an animal rearing house air circulation arrangement for a rearing house roof of low angle pitch including a fan to draw air upwards and discharge it inside the house substantially horizontally and outwardly within the pitch of the roof.

The fan may be of the axial type with the axis vertical and a deflector above the fan to provide the hoirzontal discharge.

The fan may be of the centrifugal type with the axis vertical and a suitable shroud to produce upward intake and horizontal discharge.

The fan may be of the tangential type with its axis aligned to the roof pitch and shrouded to produce the upward intake and horizontal discharge towards the roof pitch.

The fan may be of the mixed flow type.

According to invention there is provided a method of distributing air in an animal rearing house with a low-pitch roof including providing a roof space above head height, providing a fan to take in air in one direction and discharge air in a direction substantially at right angles, installing the fan with the air intake direction substantially vertical for upward air intake towards the roof space and with the air discharge direction substantially horizontal for air discharge toward the roof pitch there to be deflected downwards, whereby air circulation is produced.

Embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a cross-section of a typical broiler house using present constructional form and air circulation and Figure 2 shows a cross-section of a broiler house having air circulation according to the invention.

The broiler house in Fig. 1 has a rearing portion, which has to have a head height clearance for the stock man, and a roof portion. The height of the rearing portion is HH and set by safety considerations to above 7'.

Above this is the roof portion which accommodates a "punka" fan PF, having long, horizontal, exposed blades to drive warm air down from the roof portion. To accommodate the fan PF a roof pitch angle of some 30 to 40 degrees is required (PA1). Such a structure is expensive to build because of the higher roof. Also such a roof contains a large proportion of the total volume of air. The fan area is restricted to less than the whole floor, affecting only the central part, as the blades must be clear of the roof.

Fig. 2 shows an improved broiler house arrangement embodying the invention. The height HH must clearly be similar, subject to an observation below, but the pitch angle PA2 is much less, say 15 to 20 degrees with consequent reduction of costs and volume of air enclosed. The invention permits the reduction of pitch angle and therefore roof height, RH2, by providing a fan which draws air up and directs it out sideways, towards the roof pitch, to cause circulation. In the illustrated embodiment the fan F is a high speed axial fan surrounded by a housing H. Such a fan would draw air in along its axis and discharge the air inwards in the same axial direction.

However, by placing the fan horizontal, with the axis vertical, and fitting a baffle B over the fan the air is directed to discharge horizontally. As the fan is "high-speed" is it a physically smaller for a given throughput than the "punka" type and can be sited in a smaller roof space. As the fan blades are enclosed they are less dangerous. As an alternative a mixed flow fan is used, a Woods (Colchester) fan type MF10/4 is suitable. A mixed flow fan is one where the rotor rotates about a vertical axis and is designed to draw in air along this axis and discharge the air at right angles to it.

Protection against dust entry into the fan mechanism may be needed.

The arrangement described is particularly useful where heaters are provided. Much less unused air volume is needed, in proportion to the volume up to head height, and the air flow can be directed on to the heaters placed alongside the fans, again avoiding any increase in height.

In an alternative arrangement suitably shrouded or baffled tangential fans can be used for example in two parallel lines on each side ofthe roof ridge facing outwards and drawing air in from below. However such fans are of limited power and are more suitable for narrow buildings.

The arrangment described above permits a more compact construction of an animal house and more efficient operation, both giving significant savings in capital and running costs.

The flow velocity should be in the order of 5m/s to avoid the jet of air from the fan "floating" instead of being deflected down round the roof-wall junction in the required manner. Lower speeds may be used and still be effective in some cases.

The arrangement can be used to advantage with the method of control described in UK Published Patent Application 2125191.

A further reduction of overall height may be possible as the inlet to the fan can be made safe with wire mesh and can then be within head height HH. If the roof pitch is of unsuitable form in parts of the building then a baffle or other device may be used.

Although specifically described with reference to an animal rearing house the circulation technique is clearly applicable to other large spaced inside buildings such as workshops and halls where air circulation without excessive perceived air movement, perceived as draughts and dust movement, is required, especially to redistribute warm air to cooler parts of the space.

Claims (8)

1. An air circulation arrangement for a space within a building including means to draw air upwards in the space and discharge it within the space substantially horizontally and outwardly towards the edges of the space for downward deflection to circulate within the space.

2. An air circulation arrangement according to Claim 1 for an animal rearing house having a roof of low angle pitch including a fan to draw air upwards and discharge it inside the house substantially horizontally and outwardly within the pitch of the roof.

3. An arrangement according to Claim 1 or Claim 2, in which said means is a fan of the axial type with the axis vertical and a deflector above the fan to produce the horizontal discharge.

4. An arrangement according to Claim 1 or Claim 2, in which said means is a fan of the centrifugal type with the axis vertical and a suitable shroud to produce upward intake and horizontal discharge.

5. An arrangment according to Claim 2, in which said means is a fan of the tangential type with its axis aligned to the roof pitch and shrouded to produce the upward intake and horizontal discharge towards the roof pitch.

6. An arrangement according to Claim 1 or Claim 2, in which said means is a fan of the mixed flow type.

7. A method of distributing air in an animal rearing house with a low-pitch roof including providing a roof space above head height, providing a fan to take in air in one direction and discharge air in a direction substantially at right angles, installing the fan with the air intake direction substantially vertical for upward air intake towards the roof space and with the air discharge direction substantially horizontal for air discharge toward the roof pitch there to be deflected downwards, whereby air circulation is produced.

8. An air circulation arrangement substantially as herein described with reference to Fig.

2 of the accompanying drawings.