The Development of Regenerator Design Solutions for Power Generation Units with Carbon Dioxide as a Working Fluid

Transition to oxy-fuel combustion power cycles with zero harmful emissions is a prospective direction of the power industry development. The so-called Allam cycle is widely known. Its key element is the multi-flow regenerative heat exchanger that operates at high temperatures and pressure drops. The amount of heat utilized in this heat exchanger remarkably influences the power production efficiency. Based on this heat exchanger thermodynamic analysis we propose a scheme of five two-flow plate type heat exchangers. Installation in the square section heat exchanging channels of 45° inclined transversal ribs allows the reduction of the expensive heat exchanging surfaces area. The analysis shows that the ribs application increases the Nusselt number for about two times at Reynolds numbers from 10⁴ to 10⁵ caused by intensive wall and core flows mixing. The ribs' optimal location is a 6 mm pitch, and its deviation of 1 mm reduces the Nusselt number for 1.5-3.8%.