Dynamic Modeling for Compact Recuperator in Helium Gas Turbine Direct-Cycle System

Abstract The helium gas turbine direct-cycle scheme has the advantages of high operation temperature, simple design, and compact structure. It can serve as an efficient energy conversion system (ECS) and combine with various forms of energy, so it has broad prospects for development. Recuperator is crucial to helium gas turbine direct-cycle system. Its main function is taking advantage of high temperature helium at the outlet of turbine to heat microthermal helium behind the high pressure compressor to improve the power generation efficiency of the system. The accuracy and reusability of recuperator model will affect the system modeling and simulation. It is necessary to explore the appropriate modeling and solving methods for recuperator, and analysis the transient characteristics of recuperator under different operating conditions. In this paper, the plate heat exchanger is selected as the recuperator, and the segmented lumped parameter method is adopted to calculate the dynamic characteristics under the condition of mass flow rate and temperature disturbances. The calculation results are compared with those obtained by CFD methods. It indicates that the segmented lumped parameter model is robust and agree well with the results obtained by the finite volume method. The responses of recuperator to temperature and mass flow disturbance are analyzed. The flow rate has a greater influence on the metal wall temperature distribution shape. In power regulation, changing the flow rate synchronously on both sides of recuperator, the wall temperature is basically unchanged. In load rejection, if the regulating process lasts too long, the wall temperature may suffer from a cold shock.