Huawei's indirect evaporative cooling system is designed to use the outdoor air as a ''free'' cold source while keeping the data hall supply air isolated from outdoor contaminants and moisture. Its core is the heat exchanger, where heat from the indoor (return) air side is transferred to the outdoor working air side without mixing the two air streams. To enhance heat removal on the outdoor side, a spray system wets the evaporation media or spray section, and a water pump circulates water to maintain uniform wetting and stable evaporation performance. Fans drive airflow through the indoor and outdoor paths to ensure sufficient heat transfer and maintain the required air volume and pressure. Because outdoor air is involved on the working-air side, air filters are required to reduce dust and protect the heat exchanger and internal airflow channels, improving reliability and reducing maintenance. A compressor is not a main component of indirect evaporative cooling because the system primarily relies on evaporation and heat exchange rather than mechanical refrigeration.