Investigations of geometrical and operational aspects of a dew-point air-cooling system (M-cycle)

Abstract

The Maisotsenko cycle (M-cycle), which is a dew-point air-cooling system, has been identified as a promising alternative to conventional air conditioning systems. Previous works have focused on conducting feasibility studies of using the M-cycle in various applications in different climates while the optimization of the process and the impact of important design and operational aspects received few interests. In the present work, the impacts of various geometrical and operational aspects on the M-cycle performance were theoretically investigated. Six configurations of the counter-flow M-cycle were studied and compared numerically. These configurations included a circle, a rectangle with different aspect ratios (width-to-height ratio), and a triangle with various angles. In the circle and triangle configurations, the dry and wet channels were considered to be concentric, where the dry channel was surrounded by the wet channel. However, the plates were put on each other in rectangular geometries. A heat and mass transfer model of the counter-flow M-cycle was developed and validated using the previous numerical and experimental results of Riangvilaikul and Kumar. The influences of the hydraulic diameter and the length of the channel were investigated. Furthermore, the impacts of operating conditions, such as intake air temperature, intake relative humidity, intake air velocity, and water temperature, on the overall M-cycle performance were also examined. The system's performance was expressed in terms of dew-point effectiveness, wet-bulb effectiveness, coefficient of performance, cooling capacity, and water consumption. The obtained results show that it is preferable to maintain the intake air velocity between 2 and 3 m/s for all the considered cases. The triangular geometry with a 60° angle appears to be the best geometry. In addition, the circular shape was found to be preferable to the rectangular geometries.