چكيده به لاتين
Evaporative cooling systems are recognized as a highly efficient, low-energy, and environmentally-friendly method for indoor cooling. These systems utilize the process of water evaporation to produce a cooling effect in one channel, which is used to cool the air passing through an adjacent channel, hence being referred to as Indirect Evaporative Cooling (IEC). In this study, Regenerative IEC (IEC-R) and M-Cycle IEC (IEC-M) systems with two or three channels, considering different numbers of return air flow paths, are modeled, optimized, and their performance compared. In IEC-R, the air flow that needs to be cooled in the dry channel, after branching at the end of the dry channel, is directed into the wet channel and enters the room. In IEC-M, the air flow that needs to be cooled in the dry channel, after taking branches into the wet channel, enters the room. The method for determining the optimal number of return air flow paths in two/three-channel IEC-M systems, as well as the optimization of two/three-channel IEC-M systems, and the comparison of four cases (IEC-R and IEC-M with two/three channels) under optimal system conditions, with equal cooling capacity and similar supply air volumetric flowrate, has not been seen in the literature. Numerical modeling of IEC systems was carried out by discretizing the mass, momentum, and energy conservation equations in a steady-state, one-dimensional manner using the finite difference method in MATLAB. The results of numerical modeling, with the selection of different numbers of return air flow paths, were validated against numerical results and experimental data from other sources. Subsequently, a multi-objective technical-economic optimization was conducted under specified cooling capacity and similar supply air volumetric flowrate conditions in all systems and in two different climatic conditions. System optimization was performed using objective functions, coefficient of performance, and total annual costs (including initial investment and operating costs). The optimization results showed that increasing the number of return air flow paths in IEC-R systems with two/three channels leads to a reduction in the coefficient of performance of these systems. Comparing the optimization results for Tehran, with its moderate and dry climate, the results showed that the coefficient of performance for a three-channel IEC-R system is 31.8% higher compared to a two-channel IEC-R system, 8.3% higher compared to a three-channel IEC-M system, and 40% higher compared to a two-channel IEC-M system. Furthermore, the total annual costs for the three-channel IEC-R system were 11%, 3.5%, and 8.8% higher than the three above-mentioned cases, respectively. Additionally, comparing the optimization results for Yazd, with its hot and dry climate, the coefficient of performance for a three-channel IEC-R system is 21.2% higher compared to a two-channel IEC-R system, 6.4% higher compared to a three-channel IEC-M system, and 41% higher compared to a two-channel IEC-M system. Meanwhile, the total annual costs for the three-channel IEC-R system were 10.5%, 2.7%, and 8.7% higher for the three mentioned cases, respectively.
