Search

A combined heat and power plant with regenerative closed-cycle gas turbine is considered. The heat transfer losses, irreversible adiabatic losses and irreversible pressure drop losses are considered in the plant. The expressions of dimensionless profit rate and exergy efficiency are gained. The optimal heat conductance distributions and compressor pressure ratio are derived based on maximum dimensionless profit rate and maximum exergy efficiency objectives, respectively. The results show that the heat conductance distributions and compressor pressure ratio have their optimal values which results in maximum dimensionless profit rate. The curve of maximum dimensionless profit rate and the corresponding exergy efficiency is loop-shaped one. With the increases in heat reservoir temperature ratio τ1, price ratios a and b as well as total heat exchanger inventory UT, the maximum dimensionless profit rate increases. With the decrease in a and increases in τ1, b and UT, the corresponding exergy efficiency increases. The heat reservoir temperature ratio τ2has its optimal value which leads to double maximum dimensionless profit rate. Moreover, the maximum exergy efficiency performance of the plant is also analyzed. Because the exergoeconomic performance of irreversible regenerative closed-cycle gas turbine cogeneration plant has not been investigated by the researchers before, the exergoeconomic performance optimization is conducted in this paper, and the results obtained can offer new design guidelines for this kind of cogeneration plants. Keywords: Finite time thermodynamics, Profit rate, Exergy efficiency, CHP plant, Regenerative cycle, Heat transfer effect

The present paper describes an energy efficiency project (and relevant authorities proceedings) related to a 100 MWe CHP located within an industrial facility in Italy (COD 1996). The CHP plant supplies steam and electricity to the industrial process, whilst the extra electric-energy generation is sold to the grid. Main project target was to increase the global operating and economic indicators by: • Modifying the plant in order to cope with different thermal needs from the industrial process; Obtaining the incentives named TEE – Titoli di Efficienza Energetica , related to the CAR scheme; • Reducing CO 2 emissions (“Quote CO 2” ). • Increasing the CHP global efficiency; As several European CHP plants are nowadays facing operation/performance limitations due to different actual thermal loads (typically lower) compared to the design ones; the project has hence the aim to combine the need of a plant retrofit and the eligibility for the CAR incentives, providing a financial support to the retrofit, which corresponds, in project case, to a PBT of less than 2 years. The project and iterations with GSE are still ongoing.

cited By (since 1996)3; International audience; In situ hydrogen production is carried out by a catalytic reformer kit set up into exhaust gases for a CHP plant based on spark ignition engine running under lean conditions. An overall auto-thermal reforming process is achieved. Hydrogen production is mainly dependent on O2 content in exhaust gases. Experiments are conducted at constant speed at 2 air/fuel ratios and 4 additional natural gas flow rates. H2 content varies in the range 6-10% in vol. H2 content effect is analysed with respect to performance and emissions. Comparing with EGR shows an increasing of electrical efficiency of 1% whilst heat recovery decreases by 1%. NO and HC decrease by 18% and 12%, but CO increases by 14%, respectively. The results show that: (i) graphite joints were destroyed under effect of H2 and high temperature; (ii) a cold spot appeared in the RGR line, and condensation has as consequence a carbon deposit; and (iii) no back-fire or knock occurred. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.