Direct and Indirect Evaporative cooling Systems COMBINATION INDIRECT DIRECT COOLING SYSTEM DIRECT EVAPORATIVE COOLINGThe direct cooling temperature controller is available in various models equipped with or without a heating element. In many plastic transformation processes, the required temperature of the water must be slightly higher than that of the water coming from the centralized cooling plant. INDIRECT EVAPORATIVE COOLING SYSTEM Indirect evaporative cooling cools air without added humidity. By using a cross fluted heat exchanger, the water never comes in contact with the air. Using indirect evaporative cooling for the first stage of cooling makeup air reduces energy costs.