Abstract :
[en] Although the simultaneous production of heat and power, so-called Combined Heat and Power (CHP), is from a thermodynamic point of view still the most efficient energy conversion method, cogeneration units have nowadays problems to position themselves in the current and future energy market. The increasing renewable energy penetration requires CHP units to become more flexible, especially on their currently fixed heat-to-power ratio. Within this framework, micro Gas Turbines (mGTs), as small-scale decentralized cogeneration units, offer opportunities. Since they use the recuperated Brayton cycle, they offer the theoretic option to adjust the internal heat streams to provide a flexible heat-to-power ratio as well as the unique feature of a tunable outlet temperature, making the unit feasible/interesting for a larger range of applications having a combined heat and power demand. Hence, in this paper, we assessed the impact of the use of a recuperator bypass for enhanced operational flexibility of mGTs. In a first step, the optimal pathway for the recuperator bypass, i.e., cold or hot side bypass, is selected for a typical mGT, the Turbec T100 (currently commercially available as the AE-T100), considering both thermodynamics as well as technological feasibility. Moreover, the potential performance impact on the electrical and total efficiency is calculated as well as on the total available thermal power. In a second step, the specific performance of the option of using a recuperator bypass is assessed for 2 specific cases: flexible heat-to-power ratio at low tempera
