Transient thermal simulation of counterflow compact recuperator partition plates

Design of high performance recuperators is essential for hybridized Carbonate and Solid Oxide fuel cell power plants. This work is focused on the transient thermal simulation of simplified counterflow recuperator partition plates. A finite difference scheme was written to model heat transfer in two spatial dimensions and one time. Results clearly show the effect of temperature ramping rate on transient thermal behavior. Excessive thermal stress derived from transient operation has been a crucial mode of structural degradation for conventional gas turbine recuperators. Results show that harmful temperature gradients in recuperator plates during transient operation is minimal for high temperature fuel cell ramping rates compared to conventional gas turbine ramping rates. Based on this analysis it is suggested that employing slower temperature ramping permits the use of higher performance recuperators. Stress analysis results from another study affirm this declaration, as well as suggest that plastic strain damage incurred from transient operation may be ignored when determining recuperator service life if its temperature ramping rates are consistent with hybrid fuel cell and gas turbine systems.

► Durability of a recuperator depends on partition plates, braze connections, and fins.
► The transient thermal behavior is an important design consideration.
► Higher ramping rate yields increased heat lag in partition plates.
► Higher ramping rate results higher stress/strain and reduced service life.
► Slow ramping rate results higher compactness and/or lower pressure.