| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 87 === The topic of indoor air-pollution started to become a serious issue recently because the problem caused by indoor air pollution has showed up continually. The formation of indoor air pollution is complicated and has sources from varied areas. Let us focus on the source referred to as VOC (Volatile Organic Compound). Adhesive is a major source of VOC. We performed research on how environmental elements affect to the spreading of adhesive. Refer to the standard methods of U.S ASTM D5116-97, we set up an environmental testing chamber system and tested its function, then we selected the type of adhesive and started the experiment. During the experiment, the environmental parameters were temperature, relative humidity, and air exchange rate; the selections of parameters allow us to measure the air conditions and compare them to what we consider normal indoor conditions.
In the experiment testing how the temperature affects to the emission factor (EF), we found out that the rise of temperature will cause the polluted compound to have higher concentration during the beginning of the experiment, but it will also quickly decrease to the lowest point. we calculated the initial emission factor (EF0) and first-order decay rate constant (k) with fitting a proper chamber model. The model what we use is named the first-order decay source model. When we set the temperature to 20℃, 25℃, and 30℃, the EF0 are 935g/m2h, 983g/m2h, and 1344 g/m2h and k are 4.821h-1, 5.278h-1, and 6.075h-1; they increased gradually. Due to the increase of steam pressure and diffusion coefficients of the polluted compound caused by the rise of temperature, the emission factor increase. But due to the massive emission in the beginning of the experiment, the emission factor will decrease at a higher rate, which causes the first-order decay rate constant to increase.
In the experiment testing how the relative humidity affects to the emission factor, concentrations of the different relative humidity vary obviously with the change of time. When we set the relative humidity to 45% and 82%, the first-order decay rate constant are 4.821h-1 and 5.943h-1. We presumed that when the relative humidity rises, the moisture will condense in the emission surface and block the process of emission which causes emission factor to decrease at a higher rate.
In the experiment testing how the air exchange rate affects to the emission factor, we found out that the maximum value of concentration will decrease when the air exchange rate increases. Under such conditions, the time of occurrence for the maximum value will be earlier. With different air exchange rate, 0.568 h-1, 1.125 h-1, and 2.164 h-1, the maximum value of concentration will occur at 35 minutes (47.43g/m3), 25 minutes (49.392g/m3), and 15 minutes (32.933g/m3). The higher air exchange rate will increase the dilution of the polluted material in the experiment box, otherwise the accumulation of the polluted compound will increase the maximum value of concentration and delay the time of occurrence.
The concentration has a higher value in the condition of higher temperature and higher relative humidity, and initial emission factor and first-order decay rate constant are higher too. But due to the insufficient experimental data, we can''t make a further clear comparison on how temperature and the relative humidity affect each other.
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