Department of Engineering

Aarhus University

Guoqiang Zhang 1

Precision ventilation to improve indoor air

quality and reduce emission in pig housing

Guoqiang Zhang Dept. of Engineering, Aarhus University, Denmark.

E-mail: guoqiang.zhang@eng.au.dk

- Danish experiences of pit air exhaust

Department of Engineering

Aarhus University

Guoqiang Zhang

Partial Pit Air Exhaust (PPAE)

- Concept

- In a mechanical ventilation system

- In a natural ventilation system

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Using an extra air exhaust to remove the

part of most pollutant air directly from

slurry pit headspace.

Department of Engineering

Aarhus University

Guoqiang Zhang 3

Systems with mechanical

ventilation

- Ceiling diffusion/jet inlet

- Side-wall jet inlet

Department of Engineering

Aarhus University

Guoqiang Zhang

With ceiling diffusion inlet – Fully slatted

floor

0-90%

5-10%

4 Pit air supply

Department of Engineering

Aarhus University

Guoqiang Zhang

With Ceiling diffusion inlet & Ceiling jet inlet

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Department of Engineering

Aarhus University

Guoqiang Zhang

With Sidewall jet inlet

0-90%

5-10%

6 Pit air supply

Department of Engineering

Aarhus University

Guoqiang Zhang

Pit ventilation layout under the slatted floor - An example

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Slu

rry p

it

Pit ventilation duct

Air supply tube with inlet

holes downward 45 °

Department of Engineering

Aarhus University

Guoqiang Zhang

In systems with ceiling diffusion inlet

– Fully production scale

A graphic by Danish Pig research, 2013

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Ceiling top exhaust

(main exhaust)

Pit exhaust

Department of Engineering

Aarhus University

Guoqiang Zhang

In systems with ceiling diffusion inlet

– Fully production scale

A photo by Danish Pig research, 2014

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Pit exhaust

air duct

Ceiling top exhaust

Department of Engineering

Aarhus University

Guoqiang Zhang

In systems with natural

ventilation

• Enhance indoor climate control – focus

on airflow pattern/air distribution

• Reduction of environmental impacts

due to dust/gas emission and

improving indoor air quality – with

effective air purification units at pit

exhaust

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Department of Engineering

Aarhus University

Guoqiang Zhang

In a naturally ventilated livestock building

In winter, it may increase

wall inlet jet momentum by

closing ridge top opening &

using only PPEV.

In most of operation period

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Department of Engineering

Aarhus University

Guoqiang Zhang

In a naturally ventilated cattle building:

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Department of Engineering

Aarhus University

Guoqiang Zhang

Summary of NH3 emissions from Danish fattening pig

facilitiesa with conventional or PPAE ventilation systems

Source Ventilation

system

Via exhaust Ventilation rate,

m3 h-1 pig-1

NH3 concentration,

ppm

NH3 emission,

g d-1 pig-1

% of emission via pit

exhaust

Koerkamp

et al. (1998) Conventional Ceiling exhaust - 14.9 7.7 -

Saha et al.

(2010) b Conventional Ceiling exhaust 48.7 6.5 4.1 -

Ceiling exhaust 61.4 3.8 2.5

PPAE Pit exhaust 11.6 10.8 1.9 43.2%

Total 80.0 - 4.4

Pedersen &

Jensen

(2010)

Conventional Ceiling exhaust 52 9.3 7.5

Ceiling exhaust 49 2.6 1.8

PPAE Pit exhaust 10 20 3.3 64.7%

Total 59 - 5.1

Zhang et al.

(2014) Ceiling exhaust 75.5 1.8 2.4

PPAE-F1 c Pit exhaust 13.3 12.5 3.0 55.6%

Total 88.8 - 5.4

Ceiling exhaust 80.6 2.3 3.0

PPAE-F2 d Pit exhaust 12.0 18.6 3.8 55.1%

Total 92.6 - 6.9

Zong et al.

(2014) c Ceiling exhaust 83.4 2.1 2.9

PPAE-C e Pit exhaust 9.9 16.6 2.7 48.2%

Total 93.3 - 5.6

Ceiling exhaust 68.1 3.4 3.8

PPAE-W f Pit exhaust 9.3 21.3 3.3 46.5%

Total 77.4 - 7.1 a all with fully or partial slatted floor; b measurement at early and middle of the fattening period; c F1 with 67% slatted floor & 33% drain floor; d F2 with part of slatted floor (1 × 2 m2) was covered; e C with diffusion ceiling / ceiling jet air inlet; f W with side-wall jet air inlet. 13

Department of Engineering

Aarhus University

Guoqiang Zhang

Ammonia emission, example Toal ammonia emission & removed via pit exhaust

y = 0.1003x - 1.1157

R2 = 0.9223

0

2

4

6

8

10

12

0 15 30 45 60 75 90 105

Pig Weight, kg pig-1

NH

3 e

mis

sio

n, g

d-1

pig

-1

○, total emission; Δ, ammonia removed via pit exhaust

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Department of Engineering

Aarhus University

Guoqiang Zhang

Important parameters for PPAE

• Ventilation rate for PPAE

• Room airflow patterns

• Floor opening ratio & configuration

• Animal’s lying area/location – buoyant force & floor covering

• PPAE opening locations

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Department of Engineering

Aarhus University

Guoqiang Zhang

Simulation of flow in building

Air flow pattern and velocity distribution (m/s) in symmetry plane of the pen at

outdoor temperature of 20 °C and no pit exhaust. To the left: Diffuse ceiling air

inlet. To the right: Diffuse ceiling in combination with ceiling air jet inlet.

Air flow pattern and velocity distribution (m/s) in symmetry plane of the pen at

outdoor temperature of 10 °C and no pit exhaust. To the left: Diffuse ceiling air

inlet. To the right: Wall jet inlet.

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Department of Engineering

Aarhus University

Guoqiang Zhang

References: - Bjerg, B., Zhang, G., & Kai, P. (2008). CFD Investigation of a Partly Pit Ventilation

System as Method to Reduces Ammonia Emission from Pig Production Units. In

Proceedings of the Eighth International Livestock Symposium (ILES VIII), Paper No.

0169, Iguassu Falls, Brazil, August 31-September 4, 2008

- Riis, A.F., Jørgensen, M., Hansen, P., 2014a. 10 % Punktudsugning via sugepunkt

midt under lejeareal i slagtesvinestald med drænet gulv i lejearealet (10 % Point air

exhaust with the exhaust opening under drain floor of the laying area in fattening pig

house, in Danish). Meddelelse 998, Videncenter for Svineproduktion (Danish Pig

Research)

- Rong L; Liu D; Pedersen E; Zhang G. (2014). Effect of climate parameters on air

exchange rate and ammonia and methane emissions from a hybrid ventilated dairy

cow building. Energy and Buildings, 82: 632–643

- Saha C K; Zhang G; Kai P; Bjerg B (2010). Effects of a Partial Pit Ventilation System

on Indoor Air Quality and Gaseous Emissions from a Growing/Finishing Pig Building.

Biosystems Engineering, 105(3), 279-287

- Zong C; Feng Y; Zhang G; Hansen MJ. (2014). Effects of different air inlets on indoor

air quality and ammonia emission from two experimental fattening pig rooms with

partial pit ventilation system - summer condition. Biosystems Engineering, 122: 163-

173

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