Life Estimation of Pressurized-Air Solar-Thermal Receiver Tubes

The operational conditions of the solar-thermal receiver for a Brayton cycle engine are challenging, and lack a large body of operational data unlike steam plants. We explore the receiver's fundamental element, a pressurized tube in time varying solar flux for a series of 30 yr service missions based on hypothetical power plant designs. We developed and compared two estimation methods to predict the receiver tube lifetime based on available creep life and fatigue data for alloy 617. We show that the choice of inelastic strain model and the level of conservatism applied through design rules will vary the lifetime predictions by orders of magnitude. Based on current data and methods, a turbine inlet temperature of 1120 K is a necessary 30-yr-life-design condition for our receiver. We also showed that even though the time at operating temperature is about three times longer for fossil fuel powered (steady) operation, the damage is always lower than cyclic operation using solar power.