| Summary: | 碩士 === 崑山科技大學 === 機械工程研究所 === 107 === There are three ways of heat transfer: convection, conduction and radiation. The heat insulation of the coating is mainly to increase the surface reflectivity and reduce the absorption of heat radiation. However, the surface with high reflectivity tends to create a dilemma that the heat can’t be absorbed when we need it. For example, in the summer, in order to insulate heat, we will paint the house white and increase the surface reflectivity. However, in winter, the house surface need to absorb the solar heat to interior room to keep it warm, and we hope to paint the house in dark colors. In this regard, this study added a reversible thermochromic material (R) to the coating, changed the color depth of the coating by temperature, and appropriately adjusting the reflectivity and absorptivity.
This study is based on white coating (W) and added with black reversible thermochromic material (r) to make the coating appear grey thermochromic coating (R), and then compared with the grey coating (G) and white coating (W) on the market for which is better on thermal absorption and reflection. Verify that whether the thermochromic coating (R) will increases the reflectivity after color becomes lighter by heat-induced. In addition, this experiment adds phase-change material (p) to the coating to compare whether the benefit of adding thermal insulation material to the coating is greater than the color change.
This experiment used four analytical methods to verify the characteristics of each coating. With the spectral analysis, to understand the reflective heat radiation capability of each material. With the temperature curve analysis, to verify the correctness of the spectral analysis. With the heat flux analysis, to understand how much heat energy is actually absorbed by the coating. With the surface average temperature analysis, to correct the data of heat flux analysis that it is unfair to some coatings.
Since the experiment is to calculate the heat flux to reach the steady state temperature, the experiment must be carried out indoors, so the heating source selects the halogen lamp, but it made the thermal radiation absorption of the thermochromic coating (R) not satisfactory. In this test environment, the thermochromic coating + phase change material (R+p) is the coating that can best express the warmth in winter and cool in summer. And as we know from the data of the spectral analysis, if we do this test under sunslight, the endothermic performance of the thermochromic coating (R) may moderate growth. On the other hand, the combination of grey coating + phase change material (G + p) is extremely not recommended, the benefit of thermal absorption and insulation are both negative growth.
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