GB2260807A - Pig parlour coaxial fans mix fresh and recirculated air - Google Patents

Abstract

An environment control system for a pig parlour (1) is described. The control system is to achieve strictly controlled uniform ventilation temperature distribution for weaned pigs. An external air inlet fan 8 is mounted co-axially with and above a recirculation fan 9 so that external and recirculated air streams impinge on each other, mix and spread out in a diffused manner transversely in radial directions from the fans. The mixed air is heated by a heater 10 required and is drawn down into the parlour by the action of the recirculation fan. A baffle plate 11 helps to assist in mixing of the air. The recirculation fan 9 is controlled accorded to external air temperature so that it reaches a maximum output for relatively low external temperatures for maximum mixing when cold air is being drawn in and minimum mixing when warm air is being drawn in. <IMAGE>

Description

"An Environment Control System for a Pig Parlour" The invention relates to an environment control system for a pig parlour where it is important that temperature and ventilation are very strictly controlled. Such a situation arises for housing of pigs when weaned from the sow for approximately twenty eight days, which is an extremely stressful period and it is vital that the environment be controlled correctly.

At present, there are many available housings and environment control systems for animals. Dutch Patent Specification No.

7802512 (Hummelink) shows a pig parlour with a roof mounted ventilation unit which allows direct input of external air and air exhaust. Such a system would not lead to uniform temperature and ventilation control as external air is directed untreated into the parlour, which would lead to a non-uniform temperature and ventilation distribution in the parlour. European Patent Specification No. 17,117 (Smulders) discloses a pig parlour which has an aperture for input of air which may be closed by an air supply valve. Sensors are used to monitor temperature and to control the valve. Again, it appears that there would not be sufficiently uniform temperature and ventilation distribution because of the manner in which external air is directed into the room untreated.

Another approach to controlling temperature and ventilation of an animal house is described in French Patent Specification No. FR 2,611,028 (Pencole). The system disclosed includes a roof mounted unit which has a fan which takes in both external air and interior air determined by the position of vane. A heater for an environment control system which operates on a similar principle is disclosed in French Patent Specification No. 2,420,917 (Palm). These systems to some extent overcome the disadvantage of the other prior art of direct impingement of external air into the housing because it is mixed with internal air on passing through the fan. However, it has been found that such a system would not be suitable for achieving the strictly controlled conditions required for weaned pigs.

One reason for this is that the system produces an airstream which in general would be of a different temperature from the air in the housing and thus there is still a problem of lack of uniformity in temperature. Further, there would be inadequate mixing of internal and external air.

The invention is directed towards providing an environment control system for a pig parlour to overcome these problems.

According to the invention, there is provided an environment control system for a pig parlour, the system comprises: an external air inlet fan, a separate recirculation fan mounted co-axially with and adjacent to the inlet fan for impingement, mixing, and spreading out in a diffuse manner of inlet and recirculation air, heaters mounted transversely of the fans, an external air temperature sensor, an internal air temperature sensor, exhaust fans mounted below the level of the inlet and recirculation fans, and a control unit connected to the inlet and recirculation fans, to the heaters, and to the temperature sensors, and comprising means for continuously varying output of the fans and the heaters accorded to monitor the internal and external air temperatures.

In one embodiment, the control comprises means for varying output of the recirculation fan inversely in relation to external air temperature.

Preferably, the control unit comprises a means for varying inlet fan output in the same direction as internal air temperature and for varying temperature of the heaters inversely in relation to internal air temperature.

Idealy, the inlet and recirculation fans are mounted about a vertical axis centrally in the parlour.

In one embodiment, the recirculation fan is mounted on a baffle plate.

In another embodiment, the exhaust fans are mounted below floor level.

The invention will be more clearly understood from the following description of some preferred embodiments thereof, given by way of example only with reference to the accompanying drawings, in which: Figs. 1 and 2 are perspective views of pig parlour incorporating an environment control system of the invention, Fig. 3 is a diagrammatic cross-sectional view of the parlour, Fig. 4 is a more detailed cross-sectional view of the portion of the pig parlour at a chimney, Fig. 5 is a perspective view from the underneath of a baffle plate and a heater forming part of the environment control system, and Figs. 6 and 7 are graphs illustrating operation of the environment control system.

Referring to the drawings, and initially to Figs. 1 and 2, there is illustrated a pig parlour 1 incorporating an environment control system of the invention. The parlour 1 comprises a wooden roof 2 and wooden walls 3 mounted on a concrete block base wall 4. The floor of the parlour is mounted above the level of the base wall 4. Portions of the environment control system visible in Figs. 1 and 2 include an electronic control unit 5 which is programmed to control output of various moving parts as described in more detail below. A chimney 6 is mounted centrally in the roof 2, and exhaust vents 7 are mounted in the block base wall 4 below the floor level.

Referring now to Figs. 3 to 5, the remaining portions of the environment control system are illustrated. An inlet fan 8 having a maximum capacity of 4,400 m3/hr is mounted in the chimney 6 and below this is mounted a recirculation fan 9 having a maximum capacity of 660m3/hr. The recirculation fan 9 is mounted directly below the inlet fan 8 and is coaxial with it. Mounted on the ceiling on either side of the recirculation fan 9 there is a pair of electric heaters 10 having control units which allow variable control between zero and a maximum output. The recirculation fan 9 is mounted on a square baffle plate 11 having a circular central aperture 12. The environment control system also includes temperature sensors, not shown, mounted both externally and internally of the pig parlour 1 and connected to the control unit 5.

The control unit 5 is programmed to control the inlet fan 8, the recirculation fan 9, and the heaters 10 in response to monitored internal and external temperature to maintain uniform ventilation and temperature distribution in the pig parlour 1. This is described now with reference in particular to Figs. 4, 6 and 7.

The control unit 5 causes both the inlet fan 8 and the recirculation fan 9 to operate simultaneously, the inlet fan 8 drawing external air downwardly into the parlour and the recirculation fan 12 drawing internal air upwardly through the aperture 12. The recirculation air flow is identified by the letter A and the external air flow by the letter B in Fig. 4.

When these two air streams meet between the fans they mix together almost completely in an homogenous manner and spread out in radial directions C from the longitudinal axis of the fans. Thus, the mixed air spreads over a very wide area beneath the ceiling in a diffuse manner and is immediately drawn downwardly by the action of the recirculation fan 9 so that it very quickly accesses the whole parlour and forms an even temperature and ventilation distribution throughout the parlour. Very quick distribution of the air is achieved because the mixed air is not in an air stream but in a diffuse envelope of air which may be drawn into the space beneath and recirculated. It will also be appreciated that there is a very large extent of mixing of air because the air streams A and B impinge on each other and spread out. The spreading out action is helped by action of the baffle plate 11.

The control unit 5 controls the output of the inlet fan 8 between a minimum of 440 m3/hr and a maximum of 4,400 m3/hr, and controls the recirculation fan 9 between a minimum of 66 m3/hr and a maximum of 660 m3/hr. It will thus be immediately noticed that there is a large capacity for drawing in external air during the warm months of the year and that recirculation never reaches a level which would cause a draught or uncomfortable conditions within the parlour.

The output of the heaters 10 is controlled on a variable basis between approximately 100 % at internal temperatures of 26"C or below and a minimum of zero output at 28"C. The inlet fan 8 is also controlled according to internal temperature and increases output between 10 % at temperatures of 28"C or below, the maximum output of 100 % at a temperature of 300C. In contrast, however, the recirculation fan 9 is controlled according to external air temperature and increases output between 10% at an external temperature of 22"C and 100% at an external temperature of 120C. Accordingly, during winter when the external temperature is low there is a large amount of recirculation while the air is still being drawn in and being "diluted" to a large extent by the operation of the recirculation fan.During summer when external temperatures are high, there is little need for recirculation and the fan operates generally at the minimum output of 10%. The relationship between the outputs of the heaters, the inlet fan and the recirculation fan and the internal temperatures are illustrated in Fig. 6. It must be emphasised that this graph may be misleading in that it may give the impression that the recirculation fan output is controlled according to internal air temperature, which it is not. The graph 6 merely illustrates the relationship between the recirculation fan output and internal air temperature which results in control of the recirculation fan according to external air temperature.

The graph of Fig. 7 illustrates the output of a temperature plotter for the internal air temperature which shows that a very even temperature during a 24 hour period is recorded during operation of the environment control system of the invention.

It will be appreciated that the invention provides for a uniform distribution of ventilation and temperature because of the very large extent to which mixing occurs, the manner in which the mixed air is distributed in a diffused manner for recirculation, and to the manner in which the fans are controlled according to internal and external temperature to achieve the optimum environment. It will also be appreciated that the invention is extremely simple and may easily be mounted in a pig parlour with a chimney.

The invention is not limited to the embodiments hereinbefore described, but may be varied in construction and detail.

Claims (7)

1. An environment control system for a pig parlour, the system comprises : - an external air inlet fan, a separate recirculation fan mounted co-axially with and adjacent to the inlet fan for impingement, mixing, and spreading out in a diffuse manner of inlet and recirculation air, heaters mounted transversely of the fans, an external air temperature sensor, an internal air temperature sensor, exhaust fans mounted below the level of the inlet and recirculation fans, and a control unit connected to the inlet and recirculation fans, to the heaters, and to the temperature sensors, and comprising means for continuously varying output of the fans and the heaters accorded to monitor the internal and external air temperatures.

2. A control system as claimed in claim 1, wherein the control unit comprises means for varying output of the recirculation fan inversely in relation to external air temperature.

3. A control system as claimed in claims 1 or 2, wherein the control unit comprises a means for varying inlet fan output in the same direction as internal air temperature and for varying temperature of the heaters inversely in relation to internal air temperature.

4. A control system as claimed in any preceding claim, wherein the inlet and recirculation fans are mounted about a vertical axis centrally in the parlour.

5. A control system as claimed in any preceding claim, wherein the recirculation fan is mounted on a baffle plate.

6. A control system as claimed in any preceding claim, wherein the exhaust fans are mounted below floor level.

7. A control system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.