The VSV Sludge/Water Heat Exchanger from CleanTek Water Solutions is a “tube in shell” heat exchanger used to heat and cool biological sludge. The 316 stainless steel sludge tubes are surrounded by duplex stainless steel rectangular cross-section water channels. The flow of the sludge and the water is crosscurrent for high efficiency. Each heat exchanger is designed for each application to optimize heat transfer and physical size. The mixing action in the sludge-turning chambers equalizes the thermal profile in the sludge tubes for efficient heat transfer. The units are constructed in accordance with Section VIII, Division I, of the ASME Pressure Vessel Code. In the sludge/sludge configuration, two units are connected with a closed water loop, allowing for recovery of the energy lost when cooling digested sludge to be used to heat up undigested sludge. 886/929-7773; www.cleantekwater.com.