Yi Liang

Heat and moisture production of commercial broilers under pad cooling or surface wetting in summer.

Evaporative cooling of ventilation air to ameliorate heat-stress of livestock and poultry in summer has been widely adopted in the Southern broiler production area in the U. S. However, water usage can be high, and cooling effect may not be satisfactory under humid condition. Intermittent surface wetting system in tunnel ventilated (TV) broiler houses were evaluated side-by-side with evaporative cooling system in commercial production settings during five flocks in summer months over three years. Data collected in the evaluation were calculated for house-level sensible and latent heat loads. Despite the total specific heat production rates of houses using two types of cooling system were equivalent under the testing conditions, the partitioning of sensible and latent heat loads were different. Sensible heat load dominated during day time in houses using evaporative cooling pads and TV, while latent heat load were the primary pathway of heat loss in houses using surface wetting and TV.

Heat Recovery Ventilators in a Broiler House to Reduce Energy Use

Heat recovery ventilators (HRV), also called air-to-air heat exchangers, extracts (recovers) heat from one air stream and delivers it to another airstream. The HRV technology has been used in industrial and residential buildings for the past decade, but not in confined animal buildings where energy consumption can be intensive. In this study, heat recovery ventilation technology was evaluated for its efficacy of providing fresh pre-heated air to improve energy efficiency during a winter flock and a mild season flock on a broiler farm in NW Arkansas. One broiler house was retrofitted with four flat-plate cross-flow heat recovery ventilators in the half-house brood chamber. The heat recovery ventilators were operated to meet the minimum ventilation rates when birds were young. As birds grew, HRVs were operated in conjunction with building exhaust fans for ventilation needs. Fresh air was pre-heated up to 25 °C, partially as a result of large amounts of condensation formed due to large amounts of latent heat in the warm air stream. The amount of energy recovered was calculated based on an energy balance across the heat recovery ventilators on the cold air side. The estimated heat recovered was equivalent to 593 and 253 gallon of propane for the winter flock and mild season flock, respectively. Electricity consumption from both the wall exhaust fans and the heat recovery ventilators were 1,218 and 728 kWh higher than those of the control house during the two test flocks. The preliminary test shows a return on investment between 4 and 5 years based on the current cost of equipment and energy prices.

Ammonia Emissions from Downtime Litter Management in Broiler Housing

In-house windrow composting of re-used litter has been adopted in certain broiler complexes in the US as a means to reduce litter microbiological population in order to improve the performance of the subsequent flock. Ammonia emissions at downtime were monitored on a broiler farm to evaluate the environmental impact of two different litter managements. Five flocks had been grown on the same litter. Litter in one house was windrowed without cake removal. Additional water was added to one-half of the litter in the house but not to the other half. Litter in the second house was renovated by pulverization to thoroughly break up the cake and mix the resulting litter. Temperatures of the windrow piles remained above 55 °C for three days. Ammonia emissions averaged 22.3 and 19.4 g/d-house from pulverization and windrowing houses over the seven-day period.

Heat Production of Windrow Composting in the Broiler Houses

In-house windrowing of built-up litter has been used by some broiler production complex to reduce pathogen loads and rejuvenate the litter for the new flock. When litter is piled up to achieve 55 C for an extended period during downtime, heat generated by the litter pile could become a significant source due to the metabolism of microorganism. Windrow trials were conducted for five flocks as litter accumulated from fresh beddings over a year period. Temperatures and relative humidity of the ambient and air inside the commercial houses were continuously recorded with portable loggers during downtime. Surface and core temperature of windrowed and un-windowed litter were recorded as well at the same time. Heat production rates were calculated directly and extremely high value is found in summer. The specific heat productions were between 0.46 and 2.82 kW/kg litter (web basis) for windrowed litter and 0.39 to 2.56 kW/ kg litter (web basis) for non-windrowed litter. The windrowed house could produce more heat per unit of litter accessible to oxygen than non-windrowed house. A heat balance was built between direct method and indirect method.

A Comparison of Particulate Matter Concentration Measured by TEOM and DustTrak

In this study, we compared two particulate matter (PM) monitoring instruments, the tapered element oscillating microbalance (TEOM) and DustTrak, operating inside a commercial broiler house. The TEOM and DustTrak were placed side by side inside a commercial broiler house between two tunnel fans. Data were collected for 7 days with PM10 heads on both instruments when the flock was 4 weeks old. In the following week, data were collected with PM2.5 heads on both instruments for a total of 3 days. The TEOM recorded an average of 600 µg/m3 higher concentration for PM10, and 25 µg/m3 lesser concentration for PM 2.5 than the DustTrak. This would amount to difference in emission rate of 335 kg/year for PM10 and 16 kg/year for PM2.5 between the two instruments. This study confirms the previous findings by other researchers that the accuracy of measurement can vary significantly among instruments.

Field Evaluation of Controlled Surface Wetting System to Cool Broiler Chickens

Two overhead, low-pressure sprinkling systems were tested for their efficacy of cooling broiler chickens in two houses (treatment) during two summer flocks, and compared to the evaporative cooling systems in two other houses (control) on a commercial broiler farm. The bird live weight, feed conversion, livability were not significantly different between the treatment houses and the control houses. The sprinkler houses had substantially higher air temperature but lower relative humidity than that in the control houses during day time in the test periods. Litter moisture conditions at the end of grow-outs were not significantly different. Cooling water in treatment houses averaged about 1/3 of those used in control houses during first summer flock, and averaged about 1/10 of those of control houses during second summer flock. Electricity for ventilation in treatment houses were higher than that in control houses during second summer flock, due to the relatively cooler ambient temperature during the second test period and tunnel fans in control houses operated slightly less than those in treatment houses.

Comparison of Point Estimates from the Litter Floor and Whole-house Monitoring of Ammonia Emissions of Poultry Houses

Ammonia emissions from mechanically-ventilated livestock houses can be quantified by measuring whole house ventilation rates and ammonia concentrations at the air inlet and fan outlets. Flux chamber method, although relatively labor intensive, is an alternative approach to provide point estimates of ammonia flux from interior animal rearing areas such as the litter floor of a broiler house. In this work, a side-by-side comparison between flux chamber method and simultaneous whole house measurements was conducted during two winter flocks of commercial broilers at the University of Arkansas Applied Broiler Research Farm, near Savoy, Arkansas. At the start of the two-flock test period, the litter was previously used for four flocks and was based on original bedding of wood shavings and rice hulls. A dynamic flux chamber was used to measure ammonia flux rates on a weekly basis for two flocks. Composite flux rates from point measurements were compared with whole house emission measurement. The range of ammonia flux during two flocks monitored was from 31.75 mg/m2h to 354.37 mg/m2h by the flux chamber method, and was from 109.34 to 775.29 mg/m2h by whole house measurement method. Generally, the ammonia flux tested by whole house measurement increased linearly with increasing of the ammonia flux tested by flux chamber method. Variations were found in different sample positions across the length and the width of the house. For each flock, the lowest ammonia flux was found in the second week of the growouts.

Energy Use Analysis of Open-Curtain vs. Totally Enclosed Broiler Houses in Northwest Arkansas

Seventeen years of electricity and propane fuel use data collected from broiler production houses at the University of Arkansas Applied Broiler Research Farm (ABRF) in Northwest Arkansas were analyzed to quantify relative effect of open-curtain vs. enclosed housing systems on energy use. The ABRF consists of four commercial-scale 12 x 121 m (40 × 400 ft) houses and raise broilers under standard production contracts. After the first sixteen years of production under open-curtain system, all four houses were converted to solid-wall enclosed system with dropped ceiling, tunnel ventilation and cooling pads in early 2006. Energy use data collected from each house included propane fuel use for heating and electricity use for ventilation fans, lighting, and total. Analyses of energy use before and after the renovation were made on a flock or yearly basis.

Preliminary Evaluation of a Wet Scrubber System to Reduce Ammonia Emission from Poultry Houses

Livestock is a major contributor to atmospheric ammonia from anthropogenic sources. Environmental Protection Agency (EPA) has estimated that ammonia emission from Concentrated Animal Feeding Operations (CAFOs) would reach over 2,000,000 tones/year by 2010 Ammonia released to the atmosphere can cause eutrophication of water bodies and acidification of soils. Excess ammonia inside CAFOs can affect overall growth and performance of animals. Poultry is a major source of ammonia to atmosphere. This research was intended to develop a simple and effective wet scrubber that can be readily implemented in commercial broiler houses for ammonia mitigation. The scrubber system consisted of an open water curtain constructed with PVC pipes that sprayed water on to exiting air. The prototype water curtain was tested on a commercial broiler house in Savoy, Arkansas and operated at three water pressures, 110 kPa, 97 kPa, and 69 kPa. The maximum ammonia removal efficiency of 73% was observed at an operating pressure of 110 kPa, and a distance of 3.6 m from the fan. The wet scrubber when fully developed would serve as a useful tool for the control of ammonia emission from confined poultry facilities.