Isothermal Airflow Characteristics in the Animal-occupied Zone of a Slot-ventilated Swine Facility

Airspeed and turbulence measurements were collected in a full-scale swine grower facility. Data were collected in three horizontal planes at eight axial locations from the inlet sidewall. Three inlet slot heights (20, 40, and 60 mm) and two fan stages resulted in six ventilating conditions investigated. The resulting 2 ¥ 3 ¥ 8 factorial experiment showed that fan stage, inlet height, and axial position from the inlet significantly affected (p \u3c 0.01) airspeed variations in the animal-occupied zone (AOZ). Correlations between the AOZ and a convenient measuring plane (MP) were sought. AOZ airspeed was highly correlated with MP airspeed (rxy = 0.91). AOZ turbulent intensity (rxy = –0.51) and turbulent kinetic energy (rxy = 0.75) were moderately correlated with MP airspeed. AOZ turbulence levels were not correlated with MP turbulence levels. A procedure, consistent with the system characteristic technique, is proposed for predicting axial variations in AOZ airspeed. The technique can be used to assess AOZ airspeed levels relative to penning layout and ventilating conditions

Assessing Air Infiltration Rates of Agricultural Use Ventilation Curtains

Curtains commonly used in the agricultural ventilation industry were evaluated for air infiltration characteristics as a function of curtain material, closure overlap distance, and wind speed in a controlled and calibrated wind tunnel. Curtain material ranged from polypropylene to woven mesh with measured specific weights varying between 168 and 866 gm/m 2 (0.6 and 2.8 oz/ft 2 ). Curtains classified as breathable allow as much as 1243 m 3 /h–m 2 (68 cfm/ft 2 ) of infiltration air at wind speeds of 13.4 m/s (30 mph). For non–breathable curtains at wind speeds of 13.4 m/s, infiltration rates were reduced to 366 m 3 /h–m 2 (20 cfm/ft 2 ) for single–layer low–density curtains to essentially 0 m 3 /h–m 2 for multi–layered insulated curtains. Curtain closure overlap distances of at least 5.1 cm (2 in.) were found to drastically reduce infiltration at the opening. A non–breathable curtain that just reaches the top of the opening (i.e., 0–cm curtain overlap) can allow nearly as much infiltration air to enter as a breathable curtain

Automated Control Logic for Naturally Ventilated Agricultural Structures

An innovative control strategy for a naturally ventilated (NV) swine finishing building was evaluated. Extensive monitoring of an existing NV-controlled swine finishing building indicated that the building temperature control was .3.C of set-point for less than 50% of the time, with 20% of the time greater than .6.C. Based on the experience gained from this monitoring, the building was modified to accommodate testing and development of a new NV control logic. Using the improved NV control logic, the building temperature was .2.C of the set-point for 91% of the time, and, .3.C for 97% of the time for a wide range of cold and mild weather conditions with no supplemental heater use. A routine using inside relative humidity feedback was used to preserve indoor air quality levels through a series of purging routines

Feedback Sensor Development for IR-Based Heaters Used in Animal Housing Micro-Climate Control

The development of a feedback control sensor for flame-based infrared (IR) heaters used in animal agriculture is described. The intended use of this sensor is to control the heating pattern at desired levels for young animals in enclosed housing applications to desired micro-climate specifications. The sensor developed was sensitive to placement position in the IR heat pattern but once a suitable location was found, representative heating temperatures in the heating pattern were described very well. The first-ordered behaving IR sensor developed had a heat-up time constant of 7.5 min and a cool-down time constant of 9.5 min. The IR sensor was demonstrated in a closed-loop control scenario where the controlled IR heating zone was maintained within ±1.2°C (±2.2°F) using a three-stage gas modulating control system

A Simplified Turbulence Model for Describing Airflow in Ceiling Slot-ventilated Enclosures

A numerical model was developed to predict flow occurring with opposing plane-wall ceiling jets representative of slot-ventilated livestock facilities. This model, termed the BETA model, was evaluated by comparing predicted axial and animal occupied zone (AOZ) velocity distributions with a low Reynold’s Number turbulence model (LBLR) and a laminar model (LAM). In addition, the BETA model results were compared with experimental results from a laboratory-scale test chamber. For opposing plane-wall ceiling jets, the predominant gradient in turbulent viscosity was predicted to occur in the vertical direction. An effective viscosity was defined as a function of the inlet Reynold’s Number (ReH) and normalized vertical height from the floor. The effective viscosity was used to selectively augment the laminar viscosity in the Navier-Stoke’s equation. Predicted comparisons between BETA and the LBLR models showed negligible differences for ventilating conditions between ReH of 35,032 and 11,752. Comparison with experimentally measured axial velocity decay indicated that the BETA model reproduced ceiling jet development as well as the LBLR model

Strength Characteristics of Swine Injection Devices

Various needle gauges, lengths, and hub material was tested under static loading conditions. Significant differences exist in the needle industry in terms of strength and failure rate. Needle breakage was found to occur only when a bent needle was straightened and then reused. Manufacturing differences were found especially in the bond that joins the needle/hub assembly resulting in significant differences in failure rat

HVAC Techniques for Modern Livestock and Poultry Production Systems

Thermal modification for housed livestock and poultry production (HLPP) systems has evolved from outside raised or uncontrolled naturally ventilated building systems into sophisticated computer-controlled cloud-analyzed complexes in the quest for producing a safe, reliable, sustainable, and efficient protein supply for our ever-growing population. This chapter discusses a few of the various HLPP systems used in the USA and details the design process in quantifying the needs for our housed livestock and poultry. Specific emphasis is placed on general building characteristics, general ventilation design features, heat stress control, and systems designed to address animal welfare

Automated controller for naturally ventilated livestock and poultry buildings

A method of controlling ventilation and air quality within naturally ventilated livestock and poultry buildings comprises placing in a controller predetermined parameters of temperature and humidity for the building in question. Temperature and humidity sensors within the building are mounted above the floor with the temperature sensors being located directly above each of the animal or poultry pens. These sensors are connected to the controller to feed through the controller actual conditions of temperature and humidity within the building. The controller compares the actual conditions of temperature and humidity within the building with the predetermined parameters of temperature and humidity stored therein. The controller then increases or decreases the draft of air capable of passing through the ventilation openings to adjust the temperature and humidity within the building to fall within the predetermined parameters in those cases when the measured conditions of temperature and humidity are outside the predetermined parameters. The automated controller for naturally ventilated livestock and poultry buildings is in communication with an elongated livestock compartment which has a plurality of closeable air openings, preferably a ridge vent in the roof and closeable windows in the sides thereof. The controller has stored data therein involving predetermined parameters of temperature and humidity

A Two-Stage Wood Chip-Based Biofilter System to Mitigate Odors from a Deep-Pit Swine Building

A mobile biofilter testing laboratory was developed where two-stage biofilters filled with western cedar and hardwood chips were examined to treat odor emissions from a deep-pit swine finishing facility in central Iowa. An automatically controlled water supply system was tested and used to control media moisture content. Odor concentrations from theinlet and biofilter treatments, gas flow pressure drop, leachate pH and ammonia concentration, and water consumption were monitored.Results indicate that the water supply system tested in this study can keep wood chip media at a high and stablemoisture content of 72% ± 3% (western cedar) and 62% ± 3% (hardwood)with a 6.4 L/m3-day water supply. Western cedar (WC) chips achieved an average reduction efficiency of 51%, 83%, and 41% for odor, H2S, and NH3, respectively, when keeping the WC moisture content at 72% and the empty bed residence time (EBRT) between 3.7 and 5.5 s. A linear relationship between media unit pressure drop and unit airflow rate was observed with two-stage biofilters having an advantage in potentially reducing media compaction.Leachate pH and NH3 concentration were measured with pH levels in the 7.2 to 7.9 range with the NH3 concentration in the 198 to 1300 mg/L as N range.The effects of three different levels of media moisture content shows that proper moisture content is a key factor for the success of wood chip biofilters, but is not a substitute for inadequate EBRT

Mitigating Odors from Agricultural Facilities: A Review of Literature Concerning Biofilters

This article reviews literature on biofilter research both in laboratories and at confined livestock facilities. The purpose is to give an up-to-date review of biofilters used to mitigate of odors and volatile organic compounds (VOCs) from agricultural facilities using biofilters. More specifically the article addresses: 1) Factors concerned in design and operation of biofilters such as media property, empty bed residence time, media moisture measurement and control, microbial ecology, construction, and operation cost; and 2) Biofilter performance such as odor/VOC reduction efficiency (RE), and air pressure drop. Lab-scale, pilot-scale, and full-scale biofilter studies were reviewed. Biofilter design and odor/VOC REs were summarized in tables for easy reference and for a perspective on the current state of the art. The relationship between the biofilter configuration/operation factors and biofiter performance was discussed. This literature study indicates: 1) Biofilters can be used as an effective technology for reducing odor/VOC emissions from animal facilities (RE up to 99% for odor and up to 86% for 16 odorous VOCs reported); 2) The three most important factors effecting biofilter performance are packing media, media moisture content, and empty bed residence time; 3) Removal efficiency, air pressure drop, and construction/operation cost are three parameters of concern when a biofilter is installed and operated; and 4) Further studies such as developing precise media moisture measurement and control technologies, bacterial structure, and long time full-scale biofilter tests are needed to better understand the biofiltration process and improve biofilter applications for agriculture