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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 combustion of biomass is a process that is increasingly used for the generation of heat and energy through different types of wood and agricultural waste. The emissions generated by the combustion of biomass include different kinds of macro- and micropollutants whose formation and concentration varies according to the physical and chemical characteristics of the biomass, the combustion conditions, the plants, and the operational parameters of the process. The aim of this work is to evaluate the effect of biomass moisture content on the formation of volatile organic compounds (VOCs) during the combustion process. Wet and dry poplar chips, with a moisture content of 43.30% and 15.00%, respectively, were used in a cogeneration plant based on a mobile grate furnace. Stack’s emissions were sampled through adsorbent tubes and subsequently analyzed by thermal desorption coupled with the GC/MS. The data obtained showed that, depending on the moisture content of the starting matrix, which inevitably influences the quality of combustion, there is significant variation in the production of VOCs.

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.

In this paper according to the calculation of chips productivity needs for gasification in the demo CHP plant for co-generation: electricity and heat, chippers were analyzed due to: the type of mobility, running for chipping and the method of delivering chips to temporary yard. The plant was planned to generate electricity power up to 200kWelec. First, in consideration were taken the chippers with medium capacity, which mainly served for chipping brushwood and leaves that remain after harvest plantations on mostly flat terrain and parks. Later, the comparative characteristics of the world's three largest manufacturers of machinery for the production of wood chips significantly larger amounts (up to 30m3/h) were given. These chippers were particularly suitable for the higher density of crops and stationed yard, in which brushwood would be brought and chip. At the end, the types of convective dryers were analyzed that could be successfully used for drying wood chips (drum and pneumatic dryer) and based on the calculation proposed the types of dryers that were available in the local market.

Mathematical models of the processes, that proceed in energetic machines and devices, in many cases are very complicated. In such cases, the exact analytical models should be equipped with the auxiliary empirical models that describe those parameters which are difficult to model in a theoretical way. Regression or neural models identified basing on measurements are rather simple and are characterized by relatively short computation time. For this reason they can be effectively applied for simulation and optimization of steering and regulation processes, as well as, for control and thermal diagnosis of operation (eq. power plants or CHP plants). In the paper regression and neural models of thermal processes developed for systems of operation control of thermal plants are presented. Theoretical-empirical model of processes proceeding in coal fired CHP plant have been applied. Simulative calculations basing on these models have been carried out. Results of simulative calculations have been used for the exergetic evaluation of considered power plant. The diagnosis procedure let to investigate the formation of exergy costs in interconnected components of the system of CHP, as well as, investigate the influence of defects in operation of components on exergy losses and on the exergetic cost in other components. [Acknowledgment. The paper has been prepared within the RECENT project (REsearch Center for Energy and New Technologies) supported by 7th Framework Programme, Theme 4, Capacities.]

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.