Abstract:
The automated humidity control system controls the humidity within a setter hall. The system continuously monitors the existing setter hall thermal conditions and electronically compares the existing conditions to computerized data describing the targeted conditions. The system then takes action to conform the existing condition to the targeted condition.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY 
     This is a non-provisional patent application claiming priority to associated provisional patent application 61/077,385 filed Jul. 1, 2008, which is hereby incorporated by reference. The current application claims priority to the associated provisional application under 35 U.S.C. 120. 
    
    
     FIELD OF THE INVENTION 
     The current invention relates to an environmental control system for poultry hatcheries (i.e. setter halls). Specifically, the invention relates to an automated system for stabilizing and optimizing setter hall humidity and temperature as well as corresponding oxygen, and carbon dioxide levels. 
     BACKGROUND OF THE INVENTION 
     Controlling the thermal environment in poultry incubators is critically important to hatchery production. Humidity plays an important role in embryonic development during incubation. The humidity of the air in the incubator regulates water loss from the egg and affects the hatchability of the egg, as well as the body weight and the overall quality of the chick. 
     Current humidity control methods are based on a simple “bang-off” control system. The use of this type of system results in highly variable humidity and air temperature. When humidity drops below a predetermined threshold, water is added via misting nozzles. The system ceases misting when an upper humidity threshold is exceeded. A drop in air temperature occurs as the water mist is evaporated, thus air temperature is susceptible to variation as well. 
     The need exists for an improved humidity control system that enables hatcheries to more precisely control environmental conditions in the incubator during embryonic development. The current invention provides an automated system that optimizes the environmental conditions within an incubator based on the dew point of the incubator air rather than on humidity alone. The current invention ensures a more stable thermal environment within an incubator and results in more consistent and better quality chicks at hatch. 
     SUMMARY OF THE INVENTION 
     The current invention is directed to a variable stage incubator humidity control system. At least one incubator is in thermal communication with a spray assembly and a sensor. The sensor senses at least relative humidity and air temperature. A controller is in communication with the sensor and the spray assembly. The controller is structured to calculate an actual dew point and compare the actual dew point with a target dew point. The controller controls the spray assembly to maintain the actual dew point in a pre-programmed range thereby controls conditions in the incubator. 
     The current invention is also directed to a variable stage setter hall humidity control system. The system comprises a reservoir in fluid communication with a pump. The pump is in fluid communication with at least one solenoid valve. Each solenoid valve is in fluid communication with a corresponding spray line. Multiple nozzles are disposed on each spray line. A controller controls the operation of the variable stage humidity system. The controller is in electrical communication with the pump and the solenoid valves as well as a sensor that senses relative humidity and air temperature. 
     In operation, the sensor directs relative humidity and air temperature data to the controller. The controller processes the information and directs the pump and the solenoid valves to operate so that fluid flows from the reservoir, through the pump and the solenoid valves, and out the misting nozzles thereby enabling the controller to maintain and control thermal environmental conditions in the setter hall within a pre-programmed hysteresis band. 
     The current invention further relates to a method of controlling the environmental conditions within a pre-programmed thermal range. A controller and at least one active spray line with misting nozzles is provided. The controller is programmed with a target dew point, time lag, and hysteresis band information. The controller reads the existing temperature and the existing relative humidity in the room in which the system is installed. The controller then calculates the actual dew point in the room based on the existing temperature and relative humidity. 
     The controller compares the target dew point with the actual dew point so that if the actual dew point is greater than the target dew point plus the hysteresis band, then the controller directs the solenoid valves to reduce the number of active misting spray lines and associated nozzles. If the dew point is less than the target dew point minus the hysteresis band, then the controller directs the solenoid valves to increase the number of active misting spray lines. The system pauses for the amount of time specified by the programmed time lag, and then restarts the process by re-measuring the temperature and relative humidity within the room. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic of the current invention. 
         FIG. 2  is a more detailed schematic of the spray delivery system. 
         FIG. 3  is a flow chart describing the control algorithm of the current invention. 
         FIG. 4  is a table showing a summary of test results for a prototype system as described in the current invention, as compared with a control which uses the system and method of the prior art. 
         FIG. 5  is a graph showing the variation in air temperature in a Test Room using the current invention, as compared with a Control Room which uses the system and method of the prior art. 
         FIG. 6  is a graph showing the variation in relative humidity in a Test Room equipped with a prototype system as described in the current invention, as compared with a Control Room which uses the system and method of the prior art. 
         FIG. 7  is a graph showing the variation in dew point temperature in a Test Room equipped with a prototype system as described in the current invention, as compared with a Control Room which uses the system and method of the prior art. 
         FIG. 8  is a histogram showing the results of a test comparing the data from a Test Room which includes a prototype system as described in the current invention, as compared with a Control Room which uses the system and method of the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the preferred embodiment, at least one poultry incubator is disposed within a large room known in the art as a “setter hall”. Multiple incubators are commonly disposed in a single setter hall. Outside air that has been filtered for contaminants is drawn into the setter hall. The filtered air is then drawn from the setter hall into the individual poultry incubators. The air is circulated through the incubators and vented back into the environment outside the hatchery facility. 
     The current invention seeks to control the thermal environment inside the incubator(s) by controlling the thermal environment within the setter hall. A schematic of the preferred embodiment of the humidity control system is shown in  FIG. 1 . In the following description, exemplary system components are shown in parenthesis after the more general functional description of each component As shown in  FIG. 1 , in the preferred embodiment, a combination temperature and relative humidity sensor  20  (HMP50, Vaisala, Helsinki, Finland) is positioned in a setter hall containing poultry incubators. The sensor  20  measures the temperature and relative humidity within the setter hall. The sensor  20  is electronically connected to an embedded controller  22  based on a microcontroller processor (PIC 18F2580). A display  21  (ACS-LCD-128X64, Ackerman Computer Sciences, Sarasota, Fla.) and membrane switch key pad  23  (ACS-LCD-168X64-MBSW, Ackerman Computer Sciences, Sarasota, Fla.) are used to display controller  22  status and setter hall conditions, and input information to the controller  22 . In alternative embodiments, additional variables such as air pressure may also be monitored by the sensor to further increase the accuracy of the dew point calculation. Similarly, water pressure in the spray lines may also be monitored and/or controlled to more tightly regulate the amount the rate at which the relative humidity is modified. 
     The controller  22  is connected to an electric diaphragm pump  26  and an array of solenoid valves  28  with solid state relays  33  (Z10D120, Opto-22, Temecula, Cal.). Fluid flows from a fluid reservoir  24  to the pump  26  via a fluid supply line  29 , and from the pump  26  to an array of solenoid valves  28  via a fluid supply line  30 . The fluid then flows from the solenoid valves  28  to a plurality of spray lines  32  via a piping network  31 . The spray lines  32  include multiple nozzles  34  (3178K61, McMaster-Carr, Chicago, Ill.). In the preferred embodiment, the nozzles  34  are rated at 0.63 gal/h at 40 psi. In alternative embodiments, the nozzles may be of any variety known in the art and the fluid delivery rate and associated pressure may be varied as required for a specific application. 
     In the preferred embodiment, the spray lines  32  are suspended from the setter hall ceiling, with nozzles  34  equally distributed down the length of the spray line  32 . The spray lines  32  may have a varying number of nozzles  34 , numbered according to a binary counting scheme (2n), such that the total number of nozzles  34  available is:
 
 k= 2(2 n −1)
 
where: k=number of nozzles
         n=number of spray lines       

     A large number of nozzles  34  can be controlled by using comparatively few valves  28  while retaining a small increment in staging with this scheme. The system can be scaled to fit design requirements simply by changing the number of spray lines  32  or nozzle type. 
     A more detailed schematic of the spray delivery system is shown in  FIG. 2 . In the preferred embodiment, the piping is sized to minimize pressure drop and achieve an even flow rate through each spray nozzle. In the prototype system, three-quarter inch schedule  40  piping provided the best balance between pressure drop and cost—however, rooms of differing dimensions may require other sizes to maintain the proper pressure drop. In alternative embodiments, essentially any dimension and design of pipe should be considered within the scope of the current invention. 
     As shown in  FIG. 2 , the fluid reservoir  24  is filled via a fill valve  25 . In operation, the fluid travels from the reservoir  24 , through a filter  37 , and to the pump  26  by means of the supply line  29 . A drain valve  27  and associated drain line  35  may be used to drain the reservoir  24  and supply line  29 . Pressure from the pump  26  is regulated by a pressure regulator  36 . Pressure may be reduced by venting any excess fluid and returning the fluid to the reservoir  24  through a return line  38 . 
     As shown in  FIG. 2 , after the fluid leaves the pump  26  it is directed through the supply line  30  to an array of solenoid valves  28  configured in parallel. The valves  28  are selectively operated by the controller  22  (see  FIG. 1 ) so that fluid flows through supply lines  31  to the associated spray lines  32  and into the setter hall through one or more nozzles  34 , as described supra. 
     The solenoid valves  28  are opened and closed by the controller  22  based on a control algorithm. The flow chart in  FIG. 3  describes the control algorithm of the current invention. As shown in the  FIG. 3  flow chart, the controller  22  references a pre-programmed target dew point (DP set ) for the setter hall room. The controller  22  also references a pre-programmed hysteresis band (ΔDP) which essentially comprises a tolerance range around DP set  in which no action will be taken, and a pre-programmed cycle time (Δt) that defines a time lag between selected system actions. The controller  22  then detects (through the sensor  20 , see  FIG. 1 ) the actual temperature T db  and relative, humidity (RH) in the setter hall. Based on T db  and RH, the controller  22  calculates the actual setter hall dew point (DP). 
     As shown in the lower portion of the  FIG. 3  flow chart, if the actual dew point (DP) is greater than the target dew point (DP set ) plus the hysteresis band range (ADP), then the number of active spray lines  32  (see  FIGS. 1 and 2 ) are reduced. However, if the actual dew point (DP) is less than the target dew point (DP set ) minus the hysteresis band range (ΔDP), then the number of active spray lines  32  is increased. 
     For example, given a target dewpoint of 60° F. with a 2° F. hysteresis band, if the dewpoint were to decrease below 58° F., the number of active spray lines would be increased. After the cycle time, the current dewpoint reading would be compared with the target dew point; an additional spray line would be turned on until the room dewpoint exceeds 62° F., at which point the number of active spray lines would be reduced by the controller to avoid over-humidifying the room air. 
     A prototype of the current humidity control system was installed in a Test Room in a commercial hatchery and compared with an identical Control Room which served as a control. Air temperature, relative humidity (RH) and dewpoint were recorded in two locations in both rooms using a miniature data logger (DS1923, Dallas Semiconductor, Sunnyvale, Calif.). Tests were conducted between Feb. 20, 2008 and Mar. 4, 2008. Differences between treatments were analyzed with an ANOVA using Microsoft Excel. 
     Preliminary data analysis shows a reduction in variability (as expressed by standard deviation of mean values) of air temperature and humidity using the prototype system. Mean values and associated standard deviations for air temperature, dewpoint temperature, and relative humidity over the entire test period are shown in the table designated  FIG. 4 . Time course plots of all variables are shown in  FIGS. 5 through 8 . Variability was reduced in all three of the tested variable thermal conditions, with reductions of 34.6, 37.4, and 52% for air temperature, relative humidity, and dewpoint temperature, respectively. Differences between means for both the Test Room and Control Room were observed in all three parameters, and were significant in all cases (P&lt;0.0001). 
     The target relative humidity for each room was set at 60%, and kept within the range of ±5%. With a target RH of 60%, the prototype system maintained the Test Room RH within a 5% range approximately 57% of the test duration as opposed to only 24% for the Control Room. 
     In  FIG. 5 , air temperature is shown on the vertical axis and the test date is shown on the horizontal. The dashed line in  FIG. 5  represents the Test Room (i.e. prototype) data and the solid line represents the Control Room data. 
     In  FIGS. 6 and 7 , relative humidity and dew point temperatures are shown on the vertical axis of each of the respective figures, and the test date is shown on the horizontal axis. In both figures, the upper curves represent the data from the Test Rooms and the lower curves represent the data from the Control room. 
     As shown in  FIGS. 5-7 , in all cases, the Test Room data shows a much greater consistency than the data from the Control Room. 
     The  FIG. 8  histogram analysis also indicates that the relative humidity was maintained in a much narrower range of operation for the prototype system Test Room when compared to the data of the Control Room. Relative humidity in the Test Room ranged from about 47% to about 83%, while the Control Room humidity ranged between about 23% and 88%. 
     For the foregoing reasons, it is clear that the invention provides an innovative humidity control system that may be used in poultry-related applications as well as applications not directly related to the poultry industry. The invention may be modified in multiple ways and applied in various technological applications. The current invention may be modified and customized as required by a specific operation or application, and the individual components may be modified to achieve a specific desired result. Although the materials of construction are not described, they may include a variety of compositions consistent with the function of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.