a vector optimization methodology applied to thermodynamic model calibration of a micro gas turbine chp plant

Abstract This paper is focused on the validation of a cogeneration plant based on micro gas turbine. The experimental data related to design working point are compared to thermodynamic model results using a multi-variable multi-objective methodology depending on a genetic optimization algorithm (MOGA-II). The result with lowest Euclidean norm in objective functions space represents the operating conditions closest to experimental data, and it highlights at the same time the reliability of chain measurement. Finally, this preferred result is plotted on turbomachinery performance maps in order to validate indirectly the methodology outcomes

A multi-variable multi-objective methodology applied to energy conversion systems

World climate change and global warming increase are two urgent and strategic issues that national and international governments have to face, and different scenarios aimed to estimate the world energy demand were realized by several research centers: each scenario distinguishes itself by energy policies over the years, and the desirable one requires many efforts to keep the temperature increase below 2°C above pre-industrial level. These efforts imply challenging targets on both primary and final energy employment, and this thesis is focused on two of them: improvement of renewable energy exploitation and reduction of final energy consumption, and energy conversion systems able to efficiently achieve these targets are cogenerated distributed plants, in particular the small scale. Nevertheless, in order to achieve significant primary energy saving, combined heat and power plants need to be designed with a substantial thermal power exploitation, as well as the design need reliable and congruent system models to evaluate the plant performances. The methodology carried out in this doctorate course was focused on the analysis of these topics and it was made by two main elements, an energy conversion system model, which describes the peculiar studied case, and a multi-variable multi-objective optimization algorithm, which depends on the specific application. In particular, two different applications of the methodology were realized, one aimed at designing the more efficient energy interaction between energy system and user and one aimed at validate thermodynamic models and experimental data congruence; the first application concerned combined heat and power plants based on internal combustion engine and gas turbine, while the second application was performed on micro gas turbines and pyro-gasification biomass plant. The methodology showed to be a potentially powerful tool about conversion energy systems analysis, due to the relevant primary energy saving related to designed cogenerated power plant and to the analysis of reliability performed on mathematical models of energy conversion systems

effects of uncertainties on the stability of the results of an optimal sized modular cogeneration plant

Abstract In the last decades, the growing concerns about global warming and climate changes effects led to specific Directive, especially in Europe, promoting the use of primary energy saving techniques. In particular, a more widespread adoption of cogeneration systems has been obtained. However, distributed energy systems do not ensure the achievement of primary energy and cost savings without a proper sizing and operation of the plant. Therefore, vector optimization algorithms could play a key role to identify optimal solutions even when conflicting goals are pursued. The potential of the proposed methodology is demonstrated showing the results achieved from a specific application

Thermal comfort monitoring in office buildings: A case study

In the framework of EPBD Directive revision, the EU is pushing Member States to pay more attention to IEQ conditions in buildings, by introducing specific requirements to be verified in the calculation methodology implemented in the national building codes. In this paper, the extensive field monitoring of an office building, carried out in the heating, cooling and intermediate seasons of 2022-2023, is described. Main thermo-hygrometric quantities have been measured in different rooms, considering the occupancy profile, users’ behaviour and appliances use. Results showed overheating conditions in offices exposed to the south façade, mainly due to solar radiation and internal heat gains. Surprisingly, north-facing offices with heating terminals running are colder than south-facing ones with HVAC systems turned off. Further differences were found in the temperature analysis of free-floating conditions, showing deviations up to 4 °C on average, between south and north facing rooms. For each room, thermal comfort issues were assessed in accordance with EN 16798-1, by calculating Fanger Indexes (PMV and PPD), and by adaptive method in the HVAC systems off-work periods. These findings represent the first results of an in-depth analysis of thermal comfort and IEQ conditions, aimed at assessing how the IEQ conditions can address the building energy audit, increasing, at the same time, energy performance and IEQ levels

The energy renovation pathway to ZEB in Italy: Analysis of typical buildings and methodological aspects

The evolution towards high-energy efficient buildings is one of the most important challenges today and is in line with the objectives set by the new European Directive on the Energy Performance of Buildings (EPBD) which provides for the decarbonization of entire building stock by 2050. The study starts from the analysis of the current regulatory framework in Europe and Italy, highlighting the lack of homogeneity in the methods of transposition of European directives by the Member States already at the “nearly zero energy buildings” level (nZEB). Starting from these considerations, the critical analysis of the European and Italian context highlights the need to overcome the standards currently in force and investigate new perspectives for the design of high-efficient buildings in the direction of “zero energy and zero emissions”. For this reason, two residential and office buildings typologies are examined to confirm whether the net Zero Energy Building (ZEB) objective can be achieved through the legislation in force in Italy, starting from nZEB level. The study analyses the energy balance through dynamic simulations and evaluates energy needs of buildings and renewable energy production in order to verify the compliance to ZEB target, on yearly and monthly basis

thermodynamic model validation of capstone c30 micro gas turbine

Abstract In this work, a multi-variable multi-objective methodology aimed to perform the validation of the thermodynamic model has been applied to the Capstone C30 micro gas turbine. The methodology is based on a genetic optimization algorithm, where decision variables and objectives are set depending on available experimental data. The results of the studied case highlight the capability of the method to point out some experimental data inconsistencies and that it can lead to a consistency thermodynamic reconstruction of the micro turbine behaviour

Thermal characterization of CHP-User Needs interaction and optimized choice of the Internal Combustion Engines in the CHP plants

AbstractThis work is focused on setting up a methodology aimed to find the optimal CHP plant designs for users with thermal needs of various temperature level. A fundamental condition to ensure the Combined Heat and Power efficiency is that the thermal and the electrical power follow the user needs, in order to match with them. The thermal characterization is a necessary step to reach the goal: in fact, a qualitative temperature analysis must be done in addition to a quantitative thermal power one. In order to analyze the interaction between CHP unit and user needs, is essential to characterize the user thermal power and thermal efficiency: this analysis represents the central point of this work.The methodology is based on a multi-variable multi-objective procedure and it's adopted to examine which solutions would be able to achieve the best results in term of the Total primary Energy Saving (TPES) and the Simple pay Back (SPB) at the same time.The results of this methodology are shown with reference to three users, two hospitals and a pasta manufacturing plant

Numerical Modeling of Energy Systems Based on Micro Gas Turbine: A Review

In the context of the great research pulse on clean energy transition, distributed energy systems have a key role, especially in the case of integration of both renewable and traditional energy sources. The stable interest in small-scale gas turbines can further increase owing to their flexibility in both operation and fuel supply. Since their not-excellent electrical efficiency, research activities on micro gas turbine (MGT) are focused on the performance improvements that are achievable in several ways, like modifying the Brayton cycle, integrating two or more plants, using cleaner fuels. Hence, during the last decades, the growing interest in MGT-based energy systems encouraged the development of many numerical approaches aimed to provide a reliable and effective prediction of the energy systems’ behavior. Indeed, numerical modeling can help to individuate potentialities and issues of each enhanced layout or hybrid energy system, and this review aims to discuss the various layout solutions proposed by researchers, with particular attention to recent publications, highlighting the adopted modeling approaches and methods

Numerical Modeling of Energy Systems Based on Micro Gas Turbine: A Review

In the context of the great research pulse on clean energy transition, distributed energy systems have a key role, especially in the case of integration of both renewable and traditional energy sources. The stable interest in small-scale gas turbines can further increase owing to their flexibility in both operation and fuel supply. Since their not-excellent electrical efficiency, research activities on micro gas turbine (MGT) are focused on the performance improvements that are achievable in several ways, like modifying the Brayton cycle, integrating two or more plants, using cleaner fuels. Hence, during the last decades, the growing interest in MGT-based energy systems encouraged the development of many numerical approaches aimed to provide a reliable and effective prediction of the energy systems’ behavior. Indeed, numerical modeling can help to individuate potentialities and issues of each enhanced layout or hybrid energy system, and this review aims to discuss the various layout solutions proposed by researchers, with particular attention to recent publications, highlighting the adopted modeling approaches and methods

Micro Gas Turbine Integrated With a Supercritical CO2 Brayton Cycle Turbine: Layout Comparison and Thermodynamic Analysis

In an energetic scenario where both distributed energy systems and smart energy grids gain increasing relevance, the research focus is also on the detection of new solutions to increase overall performance of small-scale energy systems. Waste heat recovery (WHR) can represent a good solution to achieve this goal, due to the possibility of converting residual thermal power in thermal engine exhausts into electrical power. The authors, in a recent study, described the opportunities related to the integration of a micro gas turbine (MGT) with a supercritical CO2 Brayton Cycle (sCO2 GT) turbine. The adoption of Supercritical Carbon Dioxide (sCO2) as working fluid in closed Brayton cycles is an old idea, already studied in the 1960s. Only in recent years this topic returned to be of interest for electric power generation (i.e. solar, nuclear, geothermal energy or coupled with traditional thermoelectric power plants as WHR). In this technical paper the authors analyzed the performance variations of different systems layout based on the integration of a topping MGT with a sCO2 GT as bottoming cycle; the performance maps for both topping and bottoming turbomachinery have been included in the thermodynamic model with the aim of investigating the part loa