Effects of the slatted floor layout on flow pattern in a manure pit and ammonia emission from pit-A CFD study

Abstract As an interface between the animal occupied zone and the manure pit, the slatted floor has significant influences on gaseous emissions in livestock buildings. Airflow motion above the floor may affect the air motion in manure pit under the slatted floor. This work aimed to investigate the effect of slatted floor layouts on the airflow pattern in a manure pit and the corresponding ammonia emission from the pit by means of the Computational Fluid Dynamics (CFD) simulations. Firstly, airflow patterns of the 1:8 model and 1:1 model under the same Reynolds number and jet momentum ratio conditions were compared. Then, airflow patterns and ammonia emission rates of the 1:1 model with both parallel and perpendicular slatted floor layouts in various velocities (from 0.1 to 1.6 m s−1) were investigated. The results showed that the airflow patterns between 1:8 and 1:1 model were different when either the Reynolds number or the jet momentum ratio was same. On the other hand, the flow pattern in the pit with parallel floor was very different from that in the pit with perpendicular floor, resulting the ammonia emission rates different. For the cases with the free stream velocity of greater than 0.8 m s−1, perpendicularly arranged slatted floor released less ammonia from pit than the parallelly arranged slatted floor did (up to 39.0% less when free stream velocity was 1.6 m s−1). When the free stream velocity was lower than 0.8 m s−1, the perpendicular floor layout resulted in more ammonia emission than the parallel floor layout. It was concluded that the scale effect should be carefully considered during scale model experiments and the layout of slatted floors should be properly designed based on the air velocity in the animal occupied zone.

[1]  H. Küchenhoff,et al.  Effects on Pulmonary Health of Neighboring Residents of Concentrated Animal Feeding Operations: Exposure Assessed Using Optimized Estimation Technique , 2011, Archives of environmental & occupational health.

[2]  J. S. Strøm,et al.  Influence of airflow and liquid properties on the mass transfer coefficient of ammonia in aqueous solutions , 2008 .

[3]  Guoqiang Zhang,et al.  Comparisons of two numerical approaches to simulate slatted floor of a slurry pit model - Large eddy simulations , 2013 .

[4]  M. Quante,et al.  Ammonia emissions in Europe, part I: Development of a dynamical ammonia emission inventory , 2016 .

[5]  Guoqiang Zhang,et al.  Assessing effect of wind tunnel sizes on air velocity and concentration boundary layers and on ammonia emission estimation using computational fluid dynamics (CFD) , 2011 .

[6]  P. Coheur,et al.  Ammonia Emissions May Be Substantially Underestimated in China. , 2017, Environmental science & technology.

[7]  A. Chmielowiec-Korzeniowska,et al.  Occupational exposure level of pig facility workers to chemical and biological pollutants. , 2017, Annals of agricultural and environmental medicine : AAEM.

[8]  Rajasekhar Balasubramanian,et al.  Ammonia in the atmosphere: a review on emission sources, atmospheric chemistry and deposition on terrestrial bodies , 2013, Environmental Science and Pollution Research.

[9]  Graham Ashcroft,et al.  Vortical structures over rectangular cavities at low speed , 2005 .

[10]  J. Giddings,et al.  NEW METHOD FOR PREDICTION OF BINARY GAS-PHASE DIFFUSION COEFFICIENTS , 1966 .

[11]  Guoqiang Zhang,et al.  Numerical modelling of airflow and gas dispersion in the pit headspace via slatted floor , 2014 .

[12]  Roland W. Melse,et al.  Air scrubbing techniques for ammonia and odor reduction at livestock operations : review of on-farm research in the Netherlands , 2005 .

[13]  J. Lelieveld,et al.  The contribution of outdoor air pollution sources to premature mortality on a global scale , 2015, Nature.

[14]  Sang-yeon Lee,et al.  Computational fluid dynamics evaluation of pig house ventilation systems for improving the internal rearing environment , 2019, Biosystems Engineering.

[15]  A.J.A. Aarnink,et al.  Development of ammonia mass transfer coefficient models for the atmosphere above two types of the slatted floors in a pig house using computational fluid dynamics , 2019, Biosystems Engineering.

[16]  Peter Demeyer,et al.  Effect of ventilation control settings on ammonia and odour emissions from a pig rearing building , 2020 .

[17]  Mario R. Mondaca,et al.  A Computational Fluid Dynamics Model of Biological Heat and Gas Generation in a Dairy Holding Area , 2018 .

[18]  P. Spreeuwenberg,et al.  Health conditions in rural areas with high livestock density: Analysis of seven consecutive years. , 2017, Environmental pollution.

[19]  I. Nezu,et al.  Hydrodynamic characteristics and related mass-transfer properties in open-channel flows with rectangular embayment zone , 2013, Environmental Fluid Mechanics.

[20]  Bjarne Bjerg,et al.  Partial Pit Exhaust Improves Indoor Air Quality and Effectiveness of Air Cleaning in Livestock Housing: A Review , 2017 .

[21]  Ji-Qin Ni,et al.  Similarity criteria for estimating gas emission from scale models , 2011 .

[22]  Shuo Yin,et al.  Assessment of porous media instead of slatted floor for modelling the airflow and ammonia emission in the pit headspace , 2016, Comput. Electron. Agric..

[23]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[24]  J. Lelieveld,et al.  The European carbon balance. Part 4: integration of carbon and other trace‐gas fluxes , 2010 .

[25]  Q. Zhong,et al.  Reynolds number dependence of flow past a shallow open cavity , 2014 .

[26]  M. Riethmuller,et al.  Vortex characteristics in laminar cavity flow at very low Mach number , 2005 .

[27]  Huei-Tau Ouyang,et al.  Similitude Criteria for a Two-dimensional Wall Jet in an Isothermal Mechanically Ventilated Enclosure , 2006 .

[28]  Guoqiang Zhang,et al.  Summary of best guidelines and validation of CFD modeling in livestock buildings to ensure prediction quality , 2016, Comput. Electron. Agric..

[29]  Jean-François Cabaraux,et al.  Ammonia emissions from pig houses: Influencing factors and mitigation techniques , 2011 .