الفهرس 
Chapter One: IntroductionOnly 14 pages are availabe for public view
 |  | from | 111 |  |  |
| | | from | 111 | | |
Abstract
Conventional air conditioning systems consume large amounts of electrical energy to achieve space adjusted criteria. Alternatively, evaporative coolers can be used for the same purpose although they are known to increase the humidity of the conditioned space. The indirect evaporative cooling is used to overcome the problem of humidity increase.
This study aims to investigate the performance of a regenerative indirect evaporative coolers from the point of view of the design process and operating conditions. So, a counter flow heat exchange between dry and wet channels was studied. In this research, a wick material is used in the wet channels to rise the water through by capillary phenomenon to avoid using a pump. Also, silica gel material was used to absorb moisture at the entrance of the dry channels to make the device compatible in humid places. The study is divided into a numerical simulation using the EES software and an experimental investigation to validate the accuracy of the model and then study all the effective parameters on the performance of indirect evaporative cooler.
In the experimental study, heat/mass exchanger designed with dry and wet channels of length, width and height 1000 mm, 5 mm and 75 mm, respectively. The system has four wet channels and three dry channels. The experimental results indicated that the wet-bulb effectiveness of the prototype ranged from 66% to 110% for all test conditions.
The results indicate that a regenerative indirect evaporative cooler achieve a higher performance (in terms of effectiveness and energy efficiency) without adding too much cost. It is found that the effectiveness and energy efficiency of the heat/mass exchanger are largely dependent upon channel geometries (in terms of length and width), the inlet air velocity, temperature and humidity of inlet air and the working-to-intake air flow ratio but less dependent on the channel height. Comparison of practical and theoretical results of the same conditions was found that deviation does not exceed ± 20%.
The theoretical results showed that the best width of heat exchanger channels ranged between 5 - 6 mm and length 900-1000 mm, the intake air velocity is 0.5-1 m/s and the working-to-intake air ratio from 0.6 to 0.7.
The results also revealed that a regenerative indirect evaporative cooler is suitable for most regions with dry, mild and hot climate only. Therefore, using desiccant material to reduce air moisture content at the inlet of the indirect evaporative cooler and hence, the system becomes suitable for humid places.