Dynamic Simulation of Fogging Systems for Animal Housing
| Autor: | Chang, Yi-Chung, 張義忠 |
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| Rok vydání: | 1997 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 85 The objective of this study is to build a dynamic model of fogging systems for animal housing, and to use the model to simulate and analyze factors affecting the thermal environment. The model was derived based on energy and mass conservation and incorporated with the consideration of solar radiation. Simulation was performed to analyze the effect of ventilation rate, solar radiation and roof material properties to the thermal environment of the animal housing. The results showed that solar radiation has strong effect to the change of indoor temperature. A difference of 10℃ between sunny days (with solar radiation of approximately 1000 W/m2) and cloudy days (200 W/m2) could be possible. A mathematical model to predict the evaporation efficiency of fogging systems was also established. The model was validated with experimental data from existing literature. Based on the model, simple functions were regressed to simplify the calculation process. The water particle size was the major factor affecting the evaporation efficiency. At a nozzle height of 1.2 m and within the range of 20℃ to 40℃, the calculated efficiency was 100% for water particle of 45 mm. Whereas for water particle of 105 mm, the evaporation efficiency decreased significantly. Temperature and humid ity were other important factors. For high temperature with low humid ity such as at 30℃ and 30%RH, water particle of 65 mm evaporated within a moving distance of 0.10 m. However, at 20℃ and 80%RH, a distance of 0.45 m was necessary for the same particle to evaporate. The particle size appeared to be the most important factor in determining the evaporation efficiency. The second and third important factors were temperature and humidity,and nozzle height, accordingly. Field experiments were also performed and the data were analyzed with the dynamic model. The experimental results showed that a decrease of 5~7℃ could be obtained with fogging systems. Ventilation during the operation of evaporative cooling helped in shorting the cooling process. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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