With increasing interest in distributed power and heat generation, microturbines (mGT) have come to play an important role in small-size energy plants, being the most competitive alternative to piston engines, thanks to their low environmental impact and reduced O&M costs. HAT technology, given special attention over the last ten years, can be exploited to enhance (mGT) thermal efficiency for power generation, at present not higher than 30% for a regenerated cycle. This paper shows that the HAT cycle, when applied to small-size energy systems, does not require such drastic changes in plant layout as in medium and large-size plants, allowing low additional investment costs. In this respect, a micro HAT cycle seems an interesting way to significantly increase thermal efficiency, specific work and to reduce NO{sub}x emissions. This paper presents a general thermodynamic assessment of a micro Humid Air cycle (mHAT) in the range 50-500 kWe, followed by a preliminary attempt to integrate existing microturbines and the humid air cycle. Thermo economic results of the integrated mHAT cycle, based on a preliminary design of all the additional components such as the saturator, demonstrates that the 500 kWe microturbine represents the best choice in the power range presented here for mHAT cycle operation. Such a cycle is shown to be already feasible in practice, even if some modifications to the combustion chamber are required. Moreover, its operational flexibility, due to the possibility of alternating dry and wet cycles, makes the mHAT cycle an attractive investment opportunity for distributed power and heat generation (micro-cogeneration).
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