Laboratory test report - the effect of scale formation on heat transfer coils

Background
EVAPCO, Inc. recently introduced new Evaporative Condensers and Closed Circuit Coolers which utilize extended surface coils. For decades extended “fin” surfaces have been used on heat transfer coils, often referred to as “finned coils” primarily in an effort to increase dry capacity. However, in the past the fin material was limited to carbon steel tubes with a “round profile” prior to hot dip galvanizing. In most cases, the fin material was applied to a few rows of the heat transfer coil as opposed to the entire coil, due to the significant increase in airside pressure drop generated by the fins. Consequently, there was either no gain or a loss in thermal performance in the evaporative mode as a result of trying to increase dry capacity through the application of fins due to higher water and airside pressure drop.

Consistent with its mission to be a market leader in product innovation, EVAPCO commenced a rigorous Research & Development program to develop a new finned coil product that would improve upon the existing technology. EVAPCO’s efforts included determining the optimum fin profile, height and spacing, as well as the optimum tube spacing required to maximize coil heat transfer efficiency. The goal was to offer a significant increase in Closed Circuit Cooler and Evaporative Condensers when operating wet (evaporative mode) and dry in the same unit footprint while utilizing less fan motor horsepower.

EVAPCO’s efforts succeeded as EVAPCO released the NEW eco-ATW Closed Circuit Coolers and eco-ATC Evaporative Condensers, which feature a new, patent pending coil technology called “Ellipti-fin™.” This technology is unique in that the fin material is applied to tubes with an “elliptical profile.” This inherently allows for greater water and /or air over the coil while minimizing pressure losses. The result of the Ellipti-fin™coil heat transfer technology is increased thermal performance in both the wet and dry modes.

In addition, EVAPCO’s revolutionary Ellipti-fin Coil Technology leads the industry by finning all rows of the “elliptical” tube coil resulting in significant Energy and Water Savings compared to conventional closed circuit coolers and evaporative condensers with bare round tubes.

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