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An experimental study was carried out to examine the effect of waffle height, including three different values oh waffle height: 1.18 mm, 1.32 mm and 1.58 mm, on the heat transfer and friction characteristics of typical fin-and-tube heat exchanger having wavy fins. A total of twenty seven samples of heat exchangers, including twenty one of them having wavy fins and the other four having plain fin configurations were tested. During the experiments, the water inlet temperature was held at 65.0±0.3℃, Frontal The test results indicate that the effect of waffle height on the heat transfer enchancement ratio, compare to plain-fin counterpart, the heat transfer coefficient and pressure drop are increased as the waffle height is increased. In addition, as the frontal velocity is increased, the effects of waffle height on heat transfer coefficient and pressure drop are more significant. The enchancement of heat transfer coefficient for the small waffle height Pd=1.18 mm relative to the plain fin surface is negligibl
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