| ホーム | 渡辺教授 | 研究 | 業績 | 装置 | メンバー | 卒業生 | 学生業績 |
| 講義 | 学会報告 | 入学希望者 | トピックス | サイトマップ |

論文題目「Solar Powerd Adsorption Cooling System Using Silica Gel-Water Pair」

Vichan Tangkengsirisin

Solar powered adsorption cooling system is very attractive for solar energy application because this system presents many interesting characteristics such as noiseless, non-corrosive and environmentally friendly components. However, one of the most important problems of this system is solar collect design. Metallic solar collector with fin have been used to solve the problem of the low thermal conductivity in solar collector. However, using metallic-finned collector also has the negative consequences due to loss by reflection and sensible heat of metallic parts. For this reason, direct-radiation absorption collector was proposed here, but data of the effect of wavelength on desorption rate and absorptivity of silica gel is not yet sufficient. The purpose of this research is to study parameters which have influence on desorption rate in order to improve efficiency of solar collector, for example the effect of wavelength, type of silica gel, and adding some additives to improve the effective thermal conductivity and radiation absorptivity of silica gel etc.,

The effect of wavelength on desorption rate was investigated by using different light energy sources: infrared lamp and solar lamp. The wavelength profiles of both lamps were checked in advance by monochrometer. The obtained data showed that infrared lamp provided a higher intensity in near IR region while solar lamp provided many sharp peaks near ultraviolet range. The total energy flux profiles of both lamps had been set equally by adjusting the distance from lamp and the voltage of lamp. Consequently, the higher in silica gel temperature and desorption rate in case of using infrared pointed out that blue silica gel have good radiation absorptivity in near IR region compared to UV region. These results were agree with theory of surface absorption and reflection of pigment that blue particle contains pigments which preferentially absorbs the red, green, and yellow components of light but reflects the blue component.

The effect of type of silica gel on desorption rate was also investigated. The experimental data showed that using blue silica gel caused a slightly higher in silica gel temperature and desorption rate compared to white silica gel. This difference can be explained by the difference of material properties and the difference in absorptivity of silica gel. The TG/DTA data showed that the maximum desorption temperature of white silica gel (165 oC) is higher than this value of blue silica gel (145 oC). It means that the desorption rate of white silica gel is slower than the blue silica gel. About the difference of absorptivity of silica gel, The portions of radiation may be reflected, absorbed, and transmitted. For opaque medium such as blue silica gel, transmission can be assumed to be zero. On the other hand, for semitransparent such as white silica gel, the transmission is dominant. Therefore if the reflection of both silica gels are assumed equally, absorptivity of white silica gel will be lower than absorptivity of blue silica gel. This prediction was agree with the experimental data.

In general, black particles have high absorptivity. Adding some black particles into silica gel may be improve the overall absorptivity. In addition, adding some small particle in packed bed can also improve the effective thermal conductivity. For these reason, adding 12-20 mesh (0.430-0.710 mm) of activated carbon into silica gel was proposed in this research in order to improve thermal conductivity and overall absorptivity of packed bed. Three amount of activated carbon: 2 g, 4 g, or 6 g, was added into silica gel and the experiment was accomplished by using infrared lamp. The experimental data showed that silica gel and desorption rate increased with increasing of amount of activated carbon. It can be concluded that adding activated carbon improve the desorption rate and increase the regeneration temperature. However, it should have the optimum value for amount of activated carbon as the mass transfer problems in packed bed.


研究論文

国際学会