By Thomas R. Norris, P.E., and Kier DeAndaConsultants in Engineering AcousticsOrinda, California USA Key Words: silencer, noise, ORC, Organic Rankin Cycle, turboexpander, ORC silencer,environmental noise, noise reduction, hearing protection, muffler AbstractNoise from the outlet pipe of large Organic Rankin Cycle (ORC) turboexpanders can impact acoustical permitting and employee job satisfaction at geothermal power plants. Specific…