Theoretical And Experimental Study On Filtered Air Positive Pressure (FAPP) Ventilation System In Poultry Houses

Through the analysis of present condition and problem at environmental control technologies in closed poultry houses, the importance of controlling epidemic spreading from atmosphere and improving winter rearing environment of poultry was expounded. Based on the research progress of China as well as the world, systematic theoretical analysis and experimental study on applying filtered air positive pressure (FAPP) ventilation system in poultry houses was made.1. A mathematical model for designing even hole discharge of perforated PVC film duct was set up. In the model, structure characteristic of duct, static pressure , flow and air performance of entrance and atmospheric pressure of poultry house were consided comprehensively. An equation for modifying temperature inside duct was first used in this model and the calculated error was decreased greatly. Through the characteristic experiment to five PVC film ducts with different hole spacing, a series of design parameter was recommended under the allowable error ( ± 10%) of hole discharge air volume per link lengh.2. On the basis of analysis of fluid region to half cross section of FAPP ventilation house, two-dimension finite element models for the house of horizontal rearing (HR) on net and the house of cage rearing (CR) were established espectively. In the model, de Vrier and Nome's fluid region supperposi-tion method was adopted to deal with the fluid region calculation of rectangle cage. Through the model analysis of fluid region and flow speed in poultry house, hole discharge angle 30°~45°, winter hole discharge speed 3~~5m/s and summer hole discharge speed 7 — 9m/s were recommended for the HR house, and 45°~ 60°, 4~6m/s and 8—10m/s for the CR house. Theoretical basis for designing FAPP Ventilation System was provided by the analysis of fluid region.3. Through the theoretical calculation and experimental analysis to friction characteristic, allowable dust weight (ADW) and efficiency of fiber filter, an equation for calculating structure characteristic of fiber filter was set up., to VVve calcvilaUon to lowr i'vYier matet\aVa , tVie error between trie calculating and the measuring was only 2. 5~7. 5%.The experiment result on measuring clean period, ADW and efficiency of two kind of filters made in Poly-fiber (Bindian 20) and Polypropylene (PP-R-11 ) of China shew that the characteristic parameters were equal or surpass to the value recommanded by some developed countries.4. Based on the model calculation, an FAPP ventilation system was made in Beijing Poultry Breeding Company. Through running test and a series of physical and chemical characteristic measurement, the distribution of flow speed in length, and breadth was given. The average temperature (T) and relative humidity (RH) , the amplitude of T and RH per day of 30 days in winter, and instantaneous T and RH in 24 hours wre measured in FAPP house, comparing house and outside, the result shew that FAPP ventilation system was superior to comparing house. The dust concentration and microrganism content were also measured in the rearing period of poultry, the value in FAPP house was junior to comparing house.5. Through the experiment of rearing effect between FAPP house and comparing house, the difference of everage body weight, even, food consum-mer and mortality between two houses, was compared. The result shew that because air cleaning and positive ventilation were adoped in FAPP house, the rearing effect was superior to the negative comparing house.The difference of investment and income between FAPP house and comparing house was analysed, and the feasibility on applying FAPP ventilation system was expounded.