A switch valve electronically controls coolant recirculation through the exhaust heat recirculation system. Exhaust Gas Recirculation techniques to reduce NOx in emissions. Emissions regulation included the fitting of an exhaust gas recirculation system. A 2016 study combined water injection with exhaust gas recirculation. In addition, a new exhaust gas recirculation system improved emissions control. Most modern engines now need exhaust gas recirculation to meet emissions standards. Turbulence is flow characterized by recirculation, eddies, and apparent randomness. Other equipment which may be optioned in the recirculation system include pool water heaters. Lautering usually consists of 3 steps&colon; mashout, recirculation, and sparging. Stone routers also have a water recirculation system. This has led to the creation of Recirculation Deep Water Culture (RDWC) systems. Most clomifene metabolism occurs hepatically, where it undergoes enterohepatic recirculation. There does not appear to be any entero-hepatic recirculation. There is some enterohepatic recirculation of CEEs. In June 2011 the fifth recirculation Sponsor Ballot, on TGs Draft 12.0, was closed.