16-27: Use Of Large Diameter Fans On Air Cooled Heat Exchangers

A significant improvement in air cooled heat exchanger technology was implemented at U.S. Geothermal’s Neal Hot Springs power plant. Large induced draft cooling tower fans were used to reduce the total number of fans from 270 to 30. O&M and power savings total $1.6 million dollars present value. Use of VFD controlled direct drive motors yielded additional power savings of $3.1 million dollars present value. Higher capital first costs were offset by innovative structural designs that reduced overall installed costs. CFD was used to show that the large fan design virtually eliminates hot air recirculation compared to 5% to 35% recirculation rates of traditional small fan designs.