Development and testing of a portable on-desk-size Maisotsenko indirect evaporative cooler for Central Saudi Arabia's climate

The Maisotsenko indirect evaporative cooler (M-cycle cooler) provides sub-wet-bulb cooling without adding humidity to the supply air. However, unlike direct evaporative cooler, M-cycle has been developed only at large scales primarily for commercial applications. This study introduces the design and testing of a novel, portable, desk-sized M-cycle cooler for localized spot cooling under Saudi Arabia's climate conditions (30–50 °C and 10–30 % relative humidity). A total of around 30 experiments is conducted, varying thermal and fluid parameters. A super-hydrophilic micro-cotton-coated membrane was used to enhance efficiency by ensuring a uniform, thin water film in the working channels. The effects of inlet airflow, airflow ratio, inlet temperature, and relative humidity are analyzed to evaluate this small cooler's suitability for Central Saudi Arabia. Results demonstrated the feasibility of achieving sub-wet-bulb supply temperatures under specific flow conditions. Higher airflow ratios yielded colder outlet temperatures but reduced supply air mass flow, with an optimal airflow ratio maximizing cooling capacity. The cooler's efficiency improved in warmer, drier conditions, delivering greater temperature drops. This compact cooler is ideal for small desk spaces, providing efficient localized dry cooling solutions.