Energy-Efficient Evaporative Cooling with Marley NCWD
January 1, 2009
The drive towards energy efficiency has increased the need for evaporative cooling more than ever. The Marley NCWD package cooling tower from SPX Cooling Technologies addresses visible plume formation and water conservation.
SPX Cooling Technologies has developed a package product that gets one step closer by translating over 40 years of wet/dry cooling tower design to a factory assembled, low maintenance crossflow cooling tower. The Marley NCWD provides the tremendous energy efficiency, low maintenance and cost effectiveness of a crossflow evaporative cooling tower with the water conservation and reduced visible plume of a dry or air-cooled system.
In 1971, Marley patented and built the first ever wet/dry cooling tower for a power plant in St. Joseph, MO. Since then over 60 wet/dry hybrid cooling towers have been in-stalled globally at some of the world's highest profile installations. Chances are the airport you flew out of recently, utilizes this technology. In 1978, Marley patented and built the first water-conservation cooling tower for a power plant in New Mexico. Until now, these towers had been primarily applied to large-scale applications and assembled on site. Their cost and lead-time were reserved for critical applications and typically out of reach for all but the most sensitive installations. By adapting this expertise to a package cooling product, the Marley NCWD now brings this capability closer to the mainstream.
Depending on climate and configuration, the NCWD can conserve up to 20 percent of the water usage of a standard cooling tower. In addition, it can be used to dramatically reduce or eliminate the visible plume typically seen at the tower air discharge during cold weather operation. This makes it ideal for customers concerned about water conservation and/or visible plume, while still maintaining the energy efficiency and cost effectiveness of evaporative cooling. Current NCWD models are configured for applications of 500 tons or greater.
The NCWD utilizes both direct contact (evaporative) and indirect contact (dry) heat exchangers in a parallel air arrangement. Basically, hot, dry air from the sensible dry heat exchanger is mixed with the moist air from the evaporative media reducing its humidity and pushing it away from the saturation curve. Dampers can be placed on the dry section to control how much air passes through each part of the tower. This maximizes the efficiency and reduces the size and installation cost. As the wet bulb temperature and heat load decrease, more air is allowed through the dry heat exchanger, preventing the visible plume and reducing water consumption. Dampers can also be placed on the wet section of the tower, further increasing its capabilities. Furthermore, for those using chemical water treatment, less water evaporation also means less blowdown and thus fewer chemicals.
All of these advantages make the Marley NCWD from SPX Cooling Technologies the right choice for the environment.
SPX Cooling Technologies