دانلود رایگان مقاله عملکرد پارچه برای کاربرد سرمایش تبخیری غیرمستقیم

Abstract

Indirect evaporative cooling, by using water evaporation to absorb heat to lower the air temperature without adding moisture, is an extremely low energy and environmentally friendly cooling principle. The properties of the wet channel surface in an indirect evaporating cooler, i.e. its moisture wicking ability, diffusivity and evaporation ability, can greatly affect cooling efficiency and performance. Irregular fibres help to divert moisture and enlarge the wetted area, thus promoting evaporation. A range of fabrics (textiles) weaved from various fibres were experimentally tested and compared to Kraft paper, which has been conventionally used as a wet surface medium in evaporative coolers. It was found that most of the textile fabrics have superior properties in moisture wicking ability, diffusivity and evaporation ability. Compared with Kraft paper, the wicking ability of some fabrics was found to be 171%e182% higher, the diffusion ability 298%e396% higher and evaporation ability 77%e93% higher. A general assessment concerning both the moisture transfer and mechanical properties found that two of the fabrics were most suitable for indirective evaporative cooling applications.

5. Conclusions

Seven different samples including six cloth fabrics and one of Kraft paper were experimentally studied in relation to their performance for indirect evaporative cooling applications. Tests were carried out to investigate their wicking ability, wetted areas, diffusion rates and evaporation rates. The results of the cloth fabrics have been analysed and compared to that of conventionally used Kraft paper. It was found that four of the fabrics have superior properties in terms of moisture wicking ability, diffusivity and evaporation ability compared to that of conventionally used Kraft paper. Two of them have low immediate diffusion ability and were considered not suitable for evaporative cooling applications. A potential mechanical problem of the fabrics for wet surface applications, i.e, wet fabric distorted when adhered to the support sheet, has been identified during the study. A general assessment concerning both the moisture transfer and mechanical properties (ease of adhesive bonding) found that Coopass® bird eye mesh fabric and Bamboo charcoal®þCoolmax active fabric are most suitable for indirect evaporative cooling applications. The two fabrics have increased vertical wicking rates of 182% and 171%, diffusion rates of 14% and 37% and evaporation rates of 20% and 14% respectively, compared to the conventional Kraft paper. It was noticed the cost of Coopass® bird eye mesh fabric is much lower than Bamboo charcoal®þCoolmax active fabric, and therefore it will be the best choice for evaporative cooling applications. Use of these fabrics therefore offer great potential to enhance the efficiency of indirect evaporative cooling systems.