Use of a high-efficiency bimetallic recuperator of micro gas turbine units with the power of under 100 kW

BACKGROUND: Modern micro gas turbine units (MGTUs) with the power of dozen of kilowatts are single-shaft and recuperative. Being in the position where improvement of new MGTU cycles is being studied, it is necessary to choose optimal parameters of the MGTU cycle according to the scheme with regeneration when developing such simple units with the aim of ensuring small size and efficiency. Nevertheless, there are several practical restrictions for the development of recuperators, related to the issue of complicated designs together with pressure losses increase caused by regeneration degree increase and to the restriction of materials quality.

AIMS: Study of influence of a recuperator on efficiency of the MGTU, as it is essential for the development of MGTUs.

METHODS: As a part of the study, the overall assessment of the influence of recuperators on parameters of an ordinary Brayton cycle with recuperation is presented in the article. The influence of main parameters, including degree of pressure increase in a compressor, inlet gas temperature and regeneration degree, on MGTU efficiency is considered in depth in the article.

RESULTS: According to the study results, it is revealed that the use of the regeneration degree of over 0,9 with low coefficient of pressure losses in recuperators for the development of modern recuperative MGTUs leads to the unit effective efficiency not exceeding 38…40% because of certain restrictions of gas temperature at the MGTU turbine inlet caused by difficulties with cooling and ensuring small size and efficiency of the unit.

CONCLUSIONS: Use of new heatproof materials is to become an important part of improvement of MGTU in future, therefore it is necessary to study new technical solution when using prospective materials of recuperators for choosing optimal parameters of the MGTU cycle with regeneration. In addition, the option of using bimetallic recuperators is considered.