Numerical analysis of high temperature minichannel heat exchanger for recuperative microturbine system

Considering the development of energy sector, distributed small-scale power generation, e.g., gas micro-CHP, is attracting considerable interest. In such installations, the heat exchanger is one of the key components possessing a significant influence on overall performance. Most studies concentrate on units operating below 900 degrees C, which do not fulfil the requirements of gas micro-CHP. Therefore, there remains a challenge to design a compact heat exchanger with passive technologies of heat transfer enhancement. This work describes the implementation of the own construction of a plate minichannel heat exchanger for high-efficiency gas microturbine engines with an external combustion chamber, supplied with air at a temperature of about 1000 degrees C. The results of this study will greatly contribute to the increase of system efficiency. To understand transport phenomena occurring inside it, a numerical model of the entire heat exchanger was developed in OpenFOAM. Defined boundary conditions were based on experimental data used also to validate the numerical model. The pressure drop experimental and numerical results agreed within the 2%-14% range, while the heat rate ones - within the 1%-8% of the range. In addition, numerical analysis exhibited the limits of thermal and exergetic efficiency values possible to be obtained, when the boundary conditions are strongly controlled. (C) 2021 The Authors. Published by Elsevier Ltd.