Impact of Gas Internal Subflows in a Turboexpander Unit Operating on an Expander-Compressor Scheme on its Power Balance

This article presents operational data from turboexpander units (TEU) wherein a stable temperature gradient across both the turboexpander and the turbocompressor coexists with its power imbalance. A hypothesis attributing this phenomenon to internal gas internal subflows within the TEU flow path is proposed. The primary objective is to investigate the effect of such internal subflows on the power balance of a TEU configured as an expander–compressor unit and to substantiate the necessi-ty of accounting for this effect during parametric diagnostics. Analytical power balance relations for the compressor and expander are formulated, incorporating potential gas internal subflows through diverse structural elements of the flow path. These relations are subsequently validated against gas-dynamic test data. Establishing that the computed power imbalance between the turbine and com-pressor may originate from internal subflows induced by wear of flow-path components enables the identification of critical assemblies requiring heightened attention during both design and operation-al phases, thereby informing future design improvements. Furthermore, prospective enhancements to the proposed methodology are examined within the framework of integrating TEU parametric di-agnostic systems with big data analytics. The most significant outcome is the quantification of spe-cific gas internal subflows exerting the greatest influence on the compressor–turbine power balance ratio, along with an upper-bound estimate of this influence. The scientific and practical relevance of these findings lies in augmenting TEU operational efficiency and reliability, providing a basis for design optimization, and enabling advanced performance monitoring methodologies.