Improved heat exchanger for power generation equipment

A heat exchanger (100) for a turbine is provided wherein the heat exchanger (100) comprises a heat transfer cell (110) comprising a sheet of material (120) having two opposed ends (130, 135) and two opposed sides (140, 145). In addition, a plurality of concavities (150) are disposed on a surface portion of the sheet of material (120) so as to cause hydrodynamic interactions and affect a heat transfer rate of the turbine between a fluid (160) and the concavities (150) when the fluid (160) is disposed over the concavities (150).