Development of a Recuperated Flameless Combustor for an Inverted Brayton Cycle Microturbine Used in Residential Micro-CHP

The paper presents recent work in the development of a clean and efficient natural gas combustor for a micro-CHP system based on a gas turbine for the residential sector. The large scale deployment of natural gas micro-CHP systems represents a great opportunity to contribute to a reduction of CO2 emissions by a substantial increase of the efficiency of primary energy source conversion. A micro-CHP system, well designed for a residential application, which means a power of 1kWe output and high efficiency (larger than 20%), may reduce annual household emissions up to factors close to 2.5. The micro-CHP system developed in this work uses a small gas turbine and an inverted Brayton cycle which advantageously allows the use of substantially larger turbomachinery components than a conventional pressurized Brayton cycle. The paper presents a new counterflow recuperator. Its design has been thoroughly studied by advanced 3D CFD to obtain compactness and high efficiency at low cost. A new flameless combustor has been developed in order to reduce to single digits the emissions of pollutants (NOx and CO) and obtain a highly efficient and stable combustion for various gases. The design methodology based on 3D CFD modelling is presented as well as experimental results demonstrating the performance of the recuperated flameless combustor for various operationg conditions.