Heat transfer tubes having dimples arranged between adjacent fins

A combined cycle power plant includes a first generator driven by a gas turbine for generating electricity. The combined cycle power plant further includes a heat recovery steam generator disposed to receive exhaust gas from the gas turbine. The heat recovery steam generator includes an evaporator having tubes receptive to water flow therethrough. The tubes are disposed to be exposed to the exhaust gas, such that a flow of the exhaust gas passes around the tubes transfers heat from the exhaust gas to the tubes and thereby the water flowing through the tubes sufficient for the water to evaporate into steam. The tubes each having an outer surface with a plurality of deformations formed therein sufficient to introduce turbulence in the flow of the exhaust gas for enhancing heat transfer from the exhaust gas to the tubes.