The Need

Large-scale recirculating heating and cooling systems, such as those for regional, district, and single-building applications, require a working fluid to be pumped across large distances from the heat source to the consumer. While large-scale systems like district heating are more energy efficient due to simultaneous production of heat and electricity in combined heat and power generation plants, a significant amount of power is consumed to counteract drag induced by pumping the working fluid across large distances. Additionally, existing drag-reducing solutions inhibit heat transfer within chillers and heat exchangers. To reduce pumping costs and maintain heat transfer rates within heat transfer equipment, a switchable, drag-reducing solution is needed.

The Technology

Researchers at The Ohio State University, led by Dr. Andrew Maxson, have developed a novel drag reducing solution which can reduce pumping costs in large-scale systems by more than 50%. The mixed surfactant solution consists of a zwitterionic surfactant and an added counterion ("ZwitCat solution"). The ZwitCat solution demonstrates improved drag reduction ability at a wide range of working fluid compositions, flow rates, and temperatures. The solution also allows for the drag reduction ability to be toggled on and off. As noted above, existing drag-reducing solutions inhibit the heat transfer wihtin chillers and heat exchangers. Since the drag reduction ability of the ZwitCat solution can be switched off during heat transfer operations, the existing heat transfer equipment and heat transfer rates are not affected.

Commercial Applications

• Large-scale recirculating heating and cooling systems
• Petroleum pipelines
• Fire-fighting operations
• Oil-well fracturing processes

Benefits/Advantages

• Pumping cost reduction of greater than 50%
• Surfactant precipitation upon dilution with water, which simplifies separation of surfactant for disposal, improves environmental acceptability, and allows the drag-reducing ability of the solution to be toggled by changing concentration
• Extreme temperature sensitivity, which allows the drag-reducing ability of the solution to be toggled by changing temperature
• Reversible flow-induced precipitation, which allows the drag-reducing ability of the solution to be toggled by changing flow rate