Evaluation of Vipertex Enhanced Heat Transfer Tubes under Fouling Conditions

Heat transfer enhancement is important in the development of high performance thermal systems. Fouling of a surface occurs when settlement or growth of unwanted material contaminates the surface to the point that the surface can no longer be used. Deposits are the result of a series of complex reactions that cause deposits to form on the surface. Economic and technical problems associated with fouling in process systems are known and documented. Parameters that influence fouling include: surface geometry, surface temperature, surface material/finish, fluid dynamics, flow velocity and fluid properties. For many conditions, fouling can be reduced but not necessarily eliminated. Vipertex (TM) enhanced surfaces are flow optimized process surfaces that increase heat transfer through a combination of factors that include: increasing fluid turbulence, secondary flow development, disruption of the thermal boundary layer and increasing the heat transfer surface area. In addition to heat transfer enhancement, the fouling rate of Vipertubes (TM) was much less than the rate of smooth tubes; additionally the total amount of fouling over a given time period was also less. This reduction in the rate of fouling is the result of secondary flow patterns that forms as a result of the patented Vipertex surface design. These secondary flows circulate near the tube surface and clean it, preventing the buildup of materials. Several Vipertubes were studied here, with flow rate and temperature data being monitored for the duration of the study. The tubes are exposed to untreated lake water for various time periods. Transient observations and heat transfer measurements of the surfaces were obtained. Fouling results presented include instantaneous and total fouling amounts. These observations support the conclusion that when compared to smooth tubes, Vipertubes provide superior thermal performance, providing heat transfer increases of more than 100 %. At the same time the surface of the Vipertubes also minimize the detrimental effects of fouling thus providing additional service time for Vipertex designs. Vipertex surfaces enhance heat transfer, minimize operating costs and recover more energy. These enhanced surfaces provide an opportunity to advance the design of many heat transfer products.