DDI Heat Exchangers Inc Designs & Manufactures unique types of Heat Exchangers & Heat Recovery Exchangers with Rectangular channels.Sold via network of Professional Rep’s in USA, Canada and other countries.The Patented Design allows for liquids of very high % solids to flow without Plugging or Baking.Direct-Sludge-to-Sludge Heat Recovery, in Waste Water Treatment Plants or Pasteurization or Molasses or Industrial Processes,allows for Energy Recovery with ROI of only 6-7 month.