Combined cycle power plant

A combined cycle power plant including at least one gas turbine and at least one steam turbine thermally connected by a heat recovery steam generator, the steam generator comprising:

• a duct configured to receive and confine gas turbine exhaust gas from the at least one gas turbine;
• heat transfer tubes disposed within the duct and having exterior surfaces for fluid communication with the gas turbine exhaust gas and interior surfaces configured for circulatory fluid communication with water and/or steam;
• and
• a metal foam cladding having a porous, axially extended surface attached to exterior surfaces of the heat transfer tubes and operable to increase heat transfer from the hot combustion exhaust gas to the water and/or steam, the porous, axially extended surface formed from the metal foam cladding comprising a plurality of axially spaced-apart, axially extended metal foam segments, the spaced apart metal foam segments having an axial height and an axial spacing therebetween, wherein the ratio of the metal foam segment height to the axial spacing therebetween is within a range of greater than 0 to about 50.