Gas Internal Combustion Engines Research Articles

Exergy, Economic, and Life-Cycle Assessment of ORC System for Waste Heat Recovery in a Natural Gas Internal Combustion Engine

In this article, an organic Rankine cycle (ORC) was integrated into a 2-MW natural gas engine to evaluate the possibility of generating electricity by recovering the engine’s exhaust heat. The operational and design variables with the greatest influence on the energy, economic, and environmental performance of the system were analyzed. Likewise, the components with greater exergy destruction were identified through the variety of different operating parameters. From the parametric results, it was found that the evaporation pressure has the greatest influence on the destruction of exergy. The highest fraction of exergy was obtained for the Shell and tube heat exchanger (ITC1) with 38% of the total exergy destruction of the system. It was also determined that the high value of the heat transfer area increases its acquisition costs and the levelized cost of energy (LCOE) of the thermal system. Therefore, these systems must have a turbine technology with an efficiency not exceeding 90% because, from this value, the LCOE of the system surpasses the LCOE of a gas turbine. Lastly, a life cycle analysis (LCA) was developed on the system operating under the selected organic working fluids. It was found that the component with the greatest environmental impact was the turbine, which reached a maximum value of 3013.65 Pts when the material was aluminum. Acetone was used as the organic working fluid.

A quasi-one-dimensional model for an outwardly opening poppet-type direct gas injector for internal combustion engines

Direct injection of compressed natural gas in internal combustion engines is a promising technology to achieve high indicated thermal efficiency and, at the same time, reduce harmful exhaust gas emissions using relatively low-cost fuel. However, the design and analysis of direct injection–compressed natural gas systems are challenging due to small injector geometries and high-speed gas flows including shocks and discontinuities. The injector design typically involves either a multi-hole configuration with inwardly opening needle or an outwardly opening poppet-type valve with small geometries, which make accessing the near-nozzle-flow field difficult in experiments. Therefore, predictive simulations can be helpful in the design and development processes. Simulations of the gas injection process are, however, computationally very expensive, as gas passages of the order of micrometers combined with a high Mach number compressible gas flow result in very small simulation time steps of the order of nanoseconds, increasing the overall computational wall time. With substantial differences between in-nozzle and in-cylinder length and velocity scales, simultaneous simulation of both regions becomes computationally expensive. Therefore, in this work, a quasi-one-dimensional nozzle-flow model for an outwardly opening poppet-type injector is developed. The model is validated by comparison with high-fidelity large-eddy simulation results for different nozzle pressure ratios. The quasi-one-dimensional nozzle-flow model is dynamically coupled to a three-dimensional flow solver through source terms in the governing equations, named as dynamically coupled source model. The dynamically coupled source model is then applied to a temporal gas jet evolution case and a cold flow engine case. The results show that the dynamically coupled source model can reasonably predict the gas jet behavior in both cases. All simulations using the new model led to reductions of computational wall time by a factor of 5 or higher.

DEVELOPMENT OF THE COMBUSTION CHAMBER OF GAS ENGINE, CONVERTED ON THE BASIS OF DIESELS D-120 OR D-144 ENGINES TO WORK FOR ON LIQUEFIED PETROLEUM GAS

The expediency of using vehicles of liquefied petroleum gas as a motor fuel, as com-pared with traditional liquid motor fuels, in particular with diesel fuel, is shown. The advantages of converting diesel engines into gas ICEs with forced ignition with respect to conversion into gas diesel engines are substantiated. The analysis of methods for reducing the compression ratio in diesel engines when converting them into gas ICEs with forced ignition has been carried out. It is shown that for converting diesel engines into gas ICEs with forced ignition, it is advisable to use the Otto thermo-dynamic cycle with a decrease in the geometric degree of compression. The choice is grounded and an open combustion chamber in the form of an inverted axisymmetric “truncated cone” is developed. The proposed shape of the combustion chamber of a gas internal combustion engine for operation in the LPG reduces the geometric compression ratio of D-120 and D-144 diesel engines with an unseparated spherical combustion chamber, which reduces the geometric compression ratio from ε = 16,5 to ε = 9,4. The developed form of the combustion chamber allows the new diesel pistons or diesel pistons which are in operation to be in operation to be refined, instead of making special new gas pistons and to reduce the geometric compression ratio of diesel engines only by increasing the combustion chamber volume in the piston. This method of reducing the geometric degree of compression using conventional lathes is the most technologically advanced and cheap, as well as the least time consuming. Keywords: self-propelled chassis SSh-2540, wheeled tractors, diesel engines D-120 and D-144, gas engine with forced ignition, liquefied petroleum gas (LPG), compression ratio of the internal com-bustion engine, vehicles operating in the LPG.

Application of Thermo-chemical Technologies for Conversion of Associated Gas in Diesel-Gas Turbine Installations for Oil and Gas Floating Units

Abstract The paper considers the issue of thermo-chemical recovery of engine’s waste heat and its further use for steam conversion of the associated gas for oil and gas floating units. The characteristics of the associated gas are presented, and problems of its application in dual-fuel medium-speed internal combustion engines are discussed. Various variants of combined diesel-gas turbine power plant with thermo-chemical heat recovery are analyzed. The heat of the gas turbine engine exhaust gas is utilized in a thermo-chemical reactor and a steam generator. The engines operate on synthesis gas, which is obtained as a result of steam conversion of the associated gas. Criteria for evaluating the effectiveness of the developed schemes are proposed. The results of mathematical modeling of processes in a 14.1 MW diesel-gas turbine power plant with waste heat recovery are presented. The effect of the steam/associated gas ratio on the efficiency criteria is analyzed. The obtained results indicate relatively high effectiveness of the scheme with separate high and low pressure thermo-chemical reactors for producing fuel gas for both gas turbine and internal combustion engines. The calculated efficiency of such a power plant for considered input parameters is 45.6%.

Hybrid solar PV/PEM fuel Cell/Diesel Generator power system for cruise ship: A case study in Stockholm, Sweden

Optimal design and performance analysis of renewable energy system to serve the cruise ship main and auxiliary power in Stockholm, Sweden is presented in this paper. The goal is to integrate renewable energy systems in small and large ships for greener and sustainable marine transport. The power load for the cruise ship was determined, and modeling and simulation analysis was used to investigate the daily and annual performance of the power system architectures including the efficiency and capacity factors of the energy conversion systems. The total electrical power generated from the solar PV, PEM fuel cell, and Diesel generator; the cost of electricity; and the greenhouse gas and particulate matter PM emissions were determined. The proposed renewable energy system offers a good penetration of renewable energy system (13.83%), and greenhouse gas and particulate emissions reduction (9.84% emissions reduction compared to baseline system using Diesel engines). The integration of renewable and clean power systems such as solar PV and PEM fuel cell (high electrical efficiency) is very attractive solution for onboard ship power generation. They are economically viable (reduce the cost of Diesel fuel), cleaner than the conventional gas turbine and internal combustion engines and reduce the dependency on fossil fuel.

Multiobjective Optimization of a Plate Heat Exchanger in a Waste Heat Recovery Organic Rankine Cycle System for Natural Gas Engines.

A multiobjective optimization of an organic Rankine cycle (ORC) evaporator, operating with toluene as the working fluid, is presented in this paper for waste heat recovery (WHR) from the exhaust gases of a 2 MW Jenbacher JMS 612 GS-N.L. gas internal combustion engine. Indirect evaporation between the exhaust gas and the organic fluid in the parallel plate heat exchanger (ITC2) implied irreversible heat transfer and high investment costs, which were considered as objective functions to be minimized. Energy and exergy balances were applied to the system components, in addition to the phenomenological equations in the ITC2, to calculate global energy indicators, such as the thermal efficiency of the configuration, the heat recovery efficiency, the overall energy conversion efficiency, the absolute increase of engine thermal efficiency, and the reduction of the break-specific fuel consumption of the system, of the system integrated with the gas engine. The results allowed calculation of the plate spacing, plate height, plate width, and chevron angle that minimized the investment cost and entropy generation of the equipment, reaching 22.04 m2 in the heat transfer area, 693.87 kW in the energy transfer by heat recovery from the exhaust gas, and 41.6% in the overall thermal efficiency of the ORC as a bottoming cycle for the engine. This type of result contributes to the inclusion of this technology in the industrial sector as a consequence of the improvement in thermal efficiency and economic viability.

Numerical Investigation of Methane Number and Wobbe Index Effects in Lean-Burn Natural Gas Spark-Ignition Combustion

A larger use of natural gas in internal combustion engines will reduce the dependence upon petroleum imports. However, large variations in gas composition as a result of the gas origin and/or gas t...

Повышение эффективности работы дизеля серии Д49 путем перевода на газомоторное топливо

Objective: Studying the effect of diesel locomotives on the use of natural gas as motor fuel. Identification of the main advantages of using natural gas in internal combustion engines. Analysis of the effect of gas engine fuel on the performance of diesel locomotive power plants. Methods: Simulation of the working process of two engines: the first – on diesel fuel, the second – on the gas mixture. Adjustment of the mathematical model according to the real parameters of 1А-5Д49-2 diesel engine, taken during the rheostat tests of 2ТЭ116 diesel locomotive. Conducting calculation and experimental studies to assess the effect of the complete replacement of diesel fuel with natural gas on the operation of the locomotive power plant; accumulation of computational and experimental data, their systematization and statistical analysis. Theoretical dependences of the change in the specific effective fuel consumption of a diesel engine operating on natural gas through the gas cycle on the position of the driver’s controller, as well as dependences of the change in the effective performance of a diesel engine have been discussed. The calculated values are compared for the diesel engine operating on natural gas and the diesel engine operating on diesel fuel. Results: The calculated dependencies of the performance of Series 1А-5Д49-2 (16ЧН26/26) diesel engine of 2ТЭ116 diesel locomotive with the use of gas engine fuel have been obtained. The obtained data has been analyzed allowing carrying out theoretical estimation of efficiency of natural gas used as gas engine fuel throughout the entire operating range of 1А-5Д49-2 (16ЧН26/26) diesel engine of 2ТЭ116 diesel locomotive. A conclusion was confirmed about the expediency and efficiency of using natural gas in railway transport, particularly diesel locomotives. The influence of replacement of diesel fuel with natural gas on the performance indicators of diesel locomotives has been determined. Practical importance: The obtained dependencies will help in forecasting and in the theoretical evaluation of the feasibility of using natural gas as a motor fuel for locomotive power plants.

Multi-component droplet evaporation model incorporating the effects of non-ideality and thermal radiation

Currently, sophisticated fuel formulation and high temperature combustion in gas turbine and internal combustion engines make it important to investigate the effects of mixture non-ideality and radiation absorption on fuel droplet evaporation. In this study, an improved evaporation model by considering activity coefficients (AC) and external thermal radiation was established to simulate the evaporation process of multi-component non-ideal fuel droplets, and droplet suspension experiment was performed to validate the proposed model. It was found that the accuracy of simulated results was enhanced by considering activity coefficients and radiation absorption, and both effects were dependent on ambient temperature. The effect of activity coefficient was significant at low temperature (503 K), under which the droplet evaporation rate in the initial period was obviously faster than that at later stage. Consequently, the droplet lifetime decreased by about 8% at low temperature when activity coefficient was taken into consideration. At high temperature (703 K), however, the effect of activity coefficient or non-ideality on the droplet evaporation rate turned out to be insignificant. The radiation had a strong influence on evaporation at high temperature with the droplet lifetime decreasing 48% when ambient temperature increased from 503 K to 703 K. There seemed to be a critical diameter, under which the effect of radiation became negligible. It is also demonstrated that the component concentration gradients existed inside the non-ideal droplets in the initial period because of relatively low mass diffusion rate. As time elapsed, the gradients gradually disappeared due to the fact the components with large activity coefficient nearly completely evaporated.

Numerical and experimental investigation of the laminar burning velocity of biofuels at atmospheric and high-pressure conditions

Premixed flame characteristics play a crucial role in most advanced combustion applications, such as gas turbines, aircraft combustors or internal combustion engines. The laminar burning velocity is one key parameter to determine the stabilisation and propagation of premixed flames. This study examined the influence of high pressures on the laminar burning velocity of biofuels and the correlation between laminar burning velocity and pressure. The investigated biofuels were pure ethanol as the state-of-the-art surrogate, pure iso-butanol as a possible alternative and several blends of ethanol/iso-octane. Due to the usage of two methods to measure the laminar burning velocity – the Heat Flux burner and the closed combustion vessel – a comparison was added for atmospheric conditions. The measured laminar burning velocities were conducted for equivalence ratios from 0.7 to 1.3, a pressure range from 1 bar(a) to 15 bar(a) and 373 K. The results were further compared to existing numerical mechanisms and literature data.The numerical mechanisms reveal prediction performances in the range of 0.2 cm/s (0.4%) and 5.2 cm/s (16.2%) for dedicated mechanisms and equivalence ratios between 0.9 and 1.1. The two methods show deviations of the laminar burning velocities between 2.3 cm/s (4.9%) and 6.7 cm/s (11.4%).

STORING RENEWABLE ENERGIES IN A SUBSTITUTE OF NATURAL GAS

This paper proposes a way to obtain valuable electric power and valuable fuel starting from renewable variable electric power plus biomass and/or waste products. Biomass/biofuel can be oxyburned using electrolytic oxygen to generate electric power. Gas turbines or internal combustion engines are suitable to such a task, but there is the problem of very high temperatures connected to oxy combustion. In the case of gas turbine the inlet temperature could be controlled by adding steam and/or carbon dioxide, while in the case of internal combustion engines only carbon dioxide could be used. In such a way the exhaust gas continues to be formed by carbon dioxide and steam which can be easily separated by condensation. Carbon dioxide is fed to a Sabatier process together with electrolytic hydrogen to generate a gas with characteristics similar to natural gas. Although electrolytic hydrogen could be used directly both in internal combustion engines and fuel cells, significant problems to hydrogen distribution and on-board storing still exists. Therefore the substitute of natural gas could be a real bridge solution for the short/medium term. A simulation has been carried out and the resulting efficiencies range from 0.52 to 0.58.

Numerical investigation of strained extinction at engine-relevant pressures: Pressure dependence and sensitivity to chemical and physical parameters for methane-based flames

Resistance to extinction by stretch and and laminar flame speed are important properties of any combustible mixture. Recent work has shown that extinction by stretch controls the overall structure of several important types of methane-based turbulent flames. The parameter used to quantify this phenomena, Extinction Strain Rate (ESR), is numerically studied here for methane-based flames across a range of pressures relevant to gas turbines and internal combustion engines, 1-40 atm. The pressure trends are compared with those of laminar flame speed which is historically better studied. Current kinetic models agree that ESR of lean flames is a non-monotonic function of pressure and that ESR of rich flames increases significantly with pressure, but are found to differ significantly in their numerical predictions of ESR, particularly at higher pressures. To better identify the source of model prediction differences and what governs the overall accuracy of the ESR predictions, various model sensitivity analyses were conducted. Pressure-dependent kinetics are shown to be vital to determining ESR pressure trends as are molecular collision efficiencies. Yet, reactions sensitivities for ESR largely mirror those for laminar flame speed calculations. Sensitivity to the transport parameter, Lennard Jones diameter, significantly exceeds reaction sensitivities for the fuel, oxidizer and bath gas. Thermodynamic parameter ESR sensitivities vary widely with pressure, but at least for enthalpy, appear insignificant when uncertainties are considered. This study informs and motivates further efforts to understand the phenomena of flame extinction by stretch at elevated pressures.

Review of the characteristics of flexible thermal generators

In modern power systems, the penetration of renewable energy sources, such as photovoltaics and wind power generation, are increasing. Renewable energy is regard as an important role in improving energy shortages. However, renewable energy would cause a high variation of net load. To reduce the high variation of net load, flexibility expansion in the generation-side is one of the solutions. This work discusses the flexibility capabilities of typical thermal power plants, particularly about the combine cycle gas turbine (CCGT) and internal combustion engines (ICE), because both of them can start up in a short time. In addition, this work also discusses about understanding these units’ flexibility as well as other capabilities, such as greenhouse gas emissions, power generation costs, and efficiency.

Comparison between 1-D and grey-box models of a SOFC

Solid Oxide Fuel Cells (SOFCs) have shown unique performance in terms of greater electrical efficiency and thermochemical integrity with the power systems compared to gas turbines and internal combustion engines. Nonetheless, simple and reliable models still must be defined. In this paper, a comparisonbetween a grey-box model and a 1-D model of a SOFC is performed to understand the impact of the heat transfer inside the cell on the internal temperature distribution of the solid electrolyte. Hence, a significant internal temperature peak of the solid electrolyte is observed for a known difference between anode and cathode inlet temperatures. Indeed, it highlights the difference between the 1-D model andthe grey-box model regarding the thermal conditioning of the SOFC. Therefore, the results of this study can be used to investigate the reliability of the thermal results of box models in system-level simulations.

DEVELOPMENT OF AN ELECTRONIC CONTROL SYSTEM FOR GAS-ENGINES WITH SPARK IGNITION, CONVERTED ON THE BASIS OF DIESEL ENGINES TO WORK FOR ON LIQUEFIED PETROLEUM GAS

The expediency and advantages of using gas motor fuels, in particular, liquefied petroleum gas with respect to traditional liquid motor fuels, are shown. Technical solutions for the use of liquefied petroleum gas by diesel engines are presented and analysed. The expediency and advantages of converting diesel engines to gas spark ignition internal combustion engines with respect to conversion to gas diesel engines. Developed by the Ukrainian synthesis technology Avenir Gaz has for converting diesel engines to gas internal combustion engines with spark ignition. According to the synthesis technology of Avenir Gaz, re-equipment of diesel engines of vehicles is carried out on the basis of the universal electronic control system for gas internal combustion engines, which is based on the multifunctional electronic microprocessor control unit Avenir Gaz 37. The developed electronic microprocessor control system for gas internal combustion engines with forced ignition has a modular structure and consists of two main and a number of additional subsystems. A schematic diagram of a universal electronic control system of a gas internal combustion engine with spark ignition for operation on liquefied petroleum gas is presented. The principle of operation of the main subsystems, which include the subsystem of power management and injection of liquefied petroleum gas by gas electromagnetic injectors into the intake manifold of a gas engine, and the principle of operation of the control subsystem of the ignition with two-spark ignition coils are described. A multifunctional electronic control unit Avenir Gaz 37 has been designed and manufactured. Non-motorized tests of the electronic control unit confirmed its performance. Based on the synthesis technology of Avenir Gaz using the universal electronic control system for gas internal combustion engines with the Avenir Gaz 37 ECU, the D-240 diesel engine was converted into a gas spark ignition internal combustion engine of the D-240-LPG model. Keywords: gas internal combustion engine with forced ignition, liquefied petroleum gas (LPG), electronic microprocessor control system for gas internal combustion engines, vehicles operating on LPG.

DEVELOPMENT OF AN ELECTRONIC CONTROL SYSTEM FOR GAS-ENGINES, CONVERTED ON THE BASIS OF TRANSPORT DIESELS TO WORK FOR ON LIQUEFIED PETROLEUM GAS

The expediency and advantage of using gas motor fuels on a relation to traditional liquid motor fuels is shown. Technical solutions for the use of gas motor fuels by diesel engines are presented and analyzed. On the basis of the analysis, the expediency of converting diesel engines into gas engines with forced ignition is justified.An electronic microprocessor control system for gas internal combustion engines with forced ignition has been developed, which has a modular structure consisting of two main and a number of additional subsystems. The structures are described and the principle of operation of the main subsystems is described, including LPG injection subsystem, as well as the ignition control subsystem. An experienced ECU was developed and created. A structural scheme of the electronic control system of a gas engine with an experienced ECU is given. The out motorized tests of the experienced ECU were carried out, which confirmed his operability.

Time-Domain Modeling of Grid-Connected CHP for Its Interaction With the Power Grid

This paper presents a nonlinear dynamic model of grid-connected combined heat and power (CHP) system that can effectively simulate the thermoelectric interactions and examine the impact of the CHP on the power grid. Based on the theorems of mass balance and energy balance, this paper studies and analyses the principles and dynamic characteristics of the main CHP components, including gas internal combustion engine, synchronous generator, waste heat exchanger, water storage tank, exhaust-heat boiler, and gas fired boiler. Then, the nonlinear time-domain models for each component are built against input and output parameters in order to facilitate the study of CHP operation under various conditions. Subsequently, a simulation method that can deal with the coupling of all models with different time constants is proposed. Finally, dynamic simulation analysis of the developed CHP model is carried out on the MATLAB/Simulink. Extensive demonstration results show that the developed models are accurate to represent the thermoelectric interactions in the gird-connected CHP and capture the impact of these gird-connected CHPs on the power grid. This study is particularly beneficial to the design of new control strategies for CHPs to maximise its efficiency and stability value to the grid.

Effect of ammonia fuel fraction on the exergetic performance of a gas turbine

Decreasing of fossil fuels and increasing global warming lead researchers to find cheap and environmentally friendly alternative energy sources. In this regard, ammonia (NH3) is a widely used feedstock. This carbon free fuel can be combusted in gas turbines or internal combustion engines, producing only nitrogen and water vapor. Nevertheless, ammonia is hard to burn because of low laminar burning velocity. In this paper, the effect of ammonia fuel fraction on the exergetic performance of a Turbec T100 micro gas turbine is investigated. Three different fuels are considered to operate the gas turbine: (i) natural gas (100%CH4), (ii) natural gas blend with %10 ammonia fraction (10%CH4-90%NH3) and (iii) natural gas blend with %20 ammonia fraction (20%CH4-80%NH3). The operating data of the micro turbine is obtained from the literature and the micro turbine is modelled with EBSILON software. It is found that %20 ammonia fraction is more environmentally benign compared to %10 ammonia fraction and natural gas fuels. The exergetic sustainability indicators are also determined as 3.168, 2.864 and 3.7 for the natural gas, 10% ammonia blend and 20% ammonia blend combustions, respectively. So, the controlling of ammonia fraction is important to sustain exergy efficiency of the micro turbine. More detailed combustion and environmental analyses are also necessary for better evaluation of environmental effects on the micro turbine during ammonia and natural gas combustions.

Combustion Performance and Unburned Hydrocarbon Emissions of a Natural Gas–Diesel Dual Fuel Engine at a Low Load Condition

The combustion of natural gas reduces fuel cost and generates less emissions of carbon dioxide and particulate matter (PM) than diesel and gasoline. Replacing diesel by natural gas in internal combustion engines is of great interest for transportation and stationary power generation. Dual fuel combustion is an efficient way to burn natural gas in internal combustion engines. In natural gas–diesel dual fuel engines, unburned hydrocarbon emissions increase with increasing natural gas fraction. Many studies have been conducted to improve the performance of natural gas–diesel dual fuel engines and reported the performance of combustion and emissions of regulated pollutants and total unburned hydrocarbon at various engine operating strategies. However, little has been reported on the emissions of different unburned hydrocarbon components. In this paper, an experimental investigation was conducted to investigate the combustion performance and emissions of various unburned hydrocarbon components, including methane, ethane, ethylene, acetylene, propylene, formaldehyde, acetaldehyde, and benzaldehyde, at a low engine load condition. The operating conditions, such as engine speed, load, intake temperature, and pressure, were well controlled during the experiment. The combustion and emissions performance of pure diesel and natural gas–diesel dual fuel combustion were compared. The effect of diesel injection timing was analyzed. The results show that appropriately advancing diesel injection timing to form a homogeneous charge compression ignition (HCCI)-like combustion is beneficial to natural gas–diesel dual fuel combustion at low load conditions. The emissions of different unburned hydrocarbon components changed in dual fuel combustion, with emissions of some unburned hydrocarbon components being primarily due to the combustion of natural gas, while those of others being more related to diesel combustion.

Micro-multigeneration prospects for residential applications in Italy

The development of multigeneration systems is evolving in different directions. One of the main directions is the extended application of the technologies at smaller sizes. Micro-multigeneration solutions aim at becoming competitive at the size of the residential users. The cost of the technologies, in particular the cost of the cogenerator, is a major limitation to the diffusion of micro-multigeneration, especially in countries (e.g., Italy) where residential customers have a limited usage of electricity to supply their facilities. This paper discusses the prospects for the application of micro-multigeneration in Italy. The modelling and analysis of a residential micro-multigeneration system are developed from the energy efficiency and economic assessment viewpoints. The analysis is carried out on a typical system composed of a natural gas internal combustion engine, a small-scale photovoltaic plant, a backup boiler, thermal energy storage and electrical energy storage. A specific analysis tool has been implemented to address the operational planning of this system during a time period of one year. The whole model has been constructed from real data of thermal and electrical demand in a housing complex in Italy. The annual running cost and the primary energy savings occurring to serve the multi-energy demand have been considered in the operational assessment. From an economical viewpoint, the model considers the price of natural gas related to the cogeneration system, the electricity prices and all the tax breaks allowed in Italy. In this way, different scenarios have been constructed and assessed. The results indicate the impact of providing incentives on the purchase cost of the technologies, leading to increase the diffusion of micro-multigeneration solutions for the residential sector in the next years.