Estimation of Effective Temperature-Dependent Thermal Properties of Glass Fiber-Reinforced Polymer for Air‐Core Reactor Insulation: A Case Study Using an Alternative Inverse Approach

Abstract

Fiber-reinforced polymers are crucial for insulating electrical equipment, necessitating accurate thermal property data for an effective thermal analysis. This case study uses a cost-effective method to thermally characterize a glass fiber-reinforced epoxy resin used in air-core reactor insulation. The approach simultaneously estimates temperature-dependent thermal conductivity (k) and specific heat (c_p) for class H/180 insulation. By analyzing transient heat conduction in a 3D composite sample under vacuum and at various temperatures, the method optimizes sensor placement, enabling accurate property estimation with a single thermocouple. The estimated through-thickness thermal conductivity at room temperature deviates by less than 6% from standard guarded hot plate measurements. The method’s reliability is confirmed by accurately retrieving the applied heat flux using the estimated properties and measured temperature data. The results are valuable for designing accurate simulation models to predict and manage the thermal behavior of air-core reactors, as implemented by GE Grid Solutions in Itajubá, Brazil.

Graphical Abstract