Current portable power generators are mainly based on internal combustion engine since they present higher values of efficiency comparing to other engines;the main reason why internal combustion engine is not convenie...Current portable power generators are mainly based on internal combustion engine since they present higher values of efficiency comparing to other engines;the main reason why internal combustion engine is not convenient for micro power generation (5 - 30 kW) is because of their heaviness. Micro and ultra micro gas turbine devices, based on a micro compressor and a micro turbine installed on the same shaft, are more suitable for this scope for several reasons. Micro turbine systems have many advantages over reciprocating engine generators, such as higher power density (with respect to size and weight), extremely low emissions and few, or just one, moving part. Those designed with foil bearings and air-cooling operate without oil, coolants or other hazardous materials. Micro turbines also have the advantage of having the majority of their waste heat contained in their relatively high temperature exhaust. Micro turbines offer several potential advantages compared to other technologies for small-scale power generation, including: a small number of moving parts, compact size, lightweight, greater efficiency, lower emissions, lower electricity costs, and opportunities to utilize waste fuels. The object of this study is the experimental tests on a stand-alone gas turbine device with a pre-heated combustion chamber (CC), to validate the fuel consumption reduction, compared to an actual and commercial device, used on air models.展开更多
Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this ...Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this study,apart from establishing stability limits and measuring post-combustion emissions,flames generated from simultaneous combustion of biodiesel and syngas were examined using C_(2)*and CH*chemiluminescence imaging to capture changes in the reaction zone.The proportion of syngas in the fuel mix was varied from 0 to 30%content(by energy contribution)while maintaining a total power output of 15 kW.The overall equivalence ratio was held at 0.7 in cases other than for determining the flammability range.The results indicate a reduction of stability limits as gas proportion in fuel blend increases.Also,chemiluminescence imaging of the two targeted species suggest a general reduction in reaction rate as well as reaction zone area and length with increase in gas ratio in the dual phase tests.Furthermore,emissions performance in the context of NOxand CO was investigated as liquid-to-gas ratios were altered.Conclusively,the study demonstrates the feasibility,limitations and potential benefits of multiphase renewable fuel combustion in a swirl-stabilised burner.展开更多
Effects of liquid fuel composition variations on characteristics of self-excited thermo-acoustic instabilities in a lean premixed,pre-vaporized gas turbine model combustor were experimentally studied.Test fuels includ...Effects of liquid fuel composition variations on characteristics of self-excited thermo-acoustic instabilities in a lean premixed,pre-vaporized gas turbine model combustor were experimentally studied.Test fuels included practical RP-3 jet fuel and its blending with iso-octane and n-dodecane,which were branched and linear alkanes respectively.Under the test conditions,dynamic pressure measurements indicated that the dominant instability frequency was highest for RP-3 flame,while RP-3/ndodecane flame exhibited the strongest instability strength.A further analysis showed that the instability frequency correlated well with the profiles of adiabatic flame temperature,and the strength of the instability highly depended on the ignition delay times of the fuels.Measurements of the flame structure and flow field with OH*chemiluminescence (CL) imaging and twodimensional particle image velocimetry (PIV) techniques indicated that changes in the fuel composition did not alter the unstable modes and general sequences of flame-flow structure oscillations.Further power spectra and proper orthogonal decomposition(POD) analysis suggested that axial oscillations along with precessing vortex core (PVC) induced helical motion predominated periodic flame structure and flow field oscillations.展开更多
Strong restrictions on emissions from marine power plants(particularly SOx,NOx)will probably be adopted in the near future.In this paper,a combined solid oxide fuel cell(SOFC)and steam turbine fuelled by natural gas i...Strong restrictions on emissions from marine power plants(particularly SOx,NOx)will probably be adopted in the near future.In this paper,a combined solid oxide fuel cell(SOFC)and steam turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector.The analyzed variant of the combined cycle includes a SOFC operated with natural gas fuel and a steam turbine with a single-pressure waste heat boiler.The calculations were performed for two types of tubular and planar SOFCs,each with an output power of 18 MW.This paper includes a detailed energy analysis of the combined system.Mass and energy balances are performed not only for the whole plant but also for each component in order to evaluate the thermal efficiency of the combined cycle.In addition,the effects of using natural gas as a fuel on the fuel cell voltage and performance are investigated.It has been found that a high overall efficiency approaching 60%may be achieved with an optimum configuration using the SOFC system.The hybrid system would also reduce emissions,fuel consumption,and improve the total system efficiency.展开更多
One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the...One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.展开更多
As the only controllable means of a micro gas turbine(MGT)combustor during unit operation,pilot fuel ratio(PFR)is the key to achieving stable combustion and low pollutant emission.This paper discusses the influence of...As the only controllable means of a micro gas turbine(MGT)combustor during unit operation,pilot fuel ratio(PFR)is the key to achieving stable combustion and low pollutant emission.This paper discusses the influence of PFR on the inner flow field structure and pollutant emissions.The steady-state three-dimensional RANS method with a 40-step reduced methane-air kinetics mechanism is used to study the reaction flow field and species field with PFR of 9.0%,12.7%,15.2%and 17.6%.Results show that,with the decrease in PFR,the axial velocity and temperature near the central axis of the combustion chamber show a tendency to decrease.A similar separation phenomenon occurred in the core pyrolysis reaction zone(measured by HCO)and oxidation zone(measured by OH),which is more conducive to promoting the oxidation of CO.The quantitative effect of the pilot flame on nitrogen oxides(NO_(x))was separated by using inert gas instead of nitrogen in combustion air.It was found that the NOx produced by the pilot flame under the operation condition with a PFR of 9.0%was 3.2×10^(−6),accounting for 17.4%of the total NOx emission,which was twice that of PFR.展开更多
In efforts to overcome an foreseeable energy crisis predicated on limited oil and gas supplies, reserves; economic variations facing the world, and of course the environmental side effects of fossil fuels, an urgent n...In efforts to overcome an foreseeable energy crisis predicated on limited oil and gas supplies, reserves; economic variations facing the world, and of course the environmental side effects of fossil fuels, an urgent need for energy sources that provide sustainable, safe and economic supplies for the world is imperative. The current fossil fuel energy system must be improved to ensure a better and cleaner transportation future for the world. Despite the fact that the marine transportation sector consumes only 5% of global petroleum production; it is responsible for 15% of the world NOx and SOx emissions. These figures must be the engine that powers the scientific research worldwide to develop new solutions for a very old energy problem. In this paper, the most effective types of marine power plants were discussed. The history of the development of each type was presented first and the technical aspects were discussed second. Also, the fuel ceils as a new type of power plants used in marine sector were briefed to give a complete overview of the past, present and future of the marine power plants development. Based on the increased worldwide concerns regarding harmful emissions, many researchers have introduced solutions to this problem, including the adoption of new cleaner fuels. This paper was guided using the same trend and by implementing the hydrogen as fuel for marine internal combustion engine, gas turbines, and fuel cells.展开更多
Qatar energy consumptions are among the highest in the world, and can easily serve double the present population. Energy conservation is a must, as the energy resources are finite, and their consumptions are increasin...Qatar energy consumptions are among the highest in the world, and can easily serve double the present population. Energy conservation is a must, as the energy resources are finite, and their consumptions are increasing at alarming rates. The country depends on desalted seawater, which consumes extensive amounts of energy, and is produced by using the least energy efficient desalting system. The desalination process is vulnerable to many factors, and strategic water storage needs to be built. The high energy consumptions are ruining the air and marine environments. Several suggestions are introduced to conserve energy in the Cogeneration Power Desalting Plants (CPDP), by moving to replace the Multi Stage Flash (MSF) desalting system by the energy efficient Seawater Reverse Osmosis System (SWRO);fully utilizing the installed power capacity to desalt water in winter, when electric power load is low, and during summer non-peak hours for strategic water storage;and modifying the simple Gas Turbines (GT) Power cycle plants to GT combined cycle to raise the Electric Power (EP) generation efficiency (to about 50%).展开更多
In this study, exergy dynamic and advanced exergy analyses are applied to theturbojet engine to assess its mexogenous, endogenous, exogenous, avoidable and unavoidableexergies under the environment conditions of 15 ...In this study, exergy dynamic and advanced exergy analyses are applied to theturbojet engine to assess its mexogenous, endogenous, exogenous, avoidable and unavoidableexergies under the environment conditions of 15 C temperature and 1 bar pressure. Themaximum exergy point in the turbojet engine is found for the combustor in which C11H23(Jet-A1) fuel is combusted with air, while the minimum one is determined for the aircompressor head where the free air enters. The combustion chamber has the maximum fuel,product and irreversibility rates and the air compressor has the minimum fuel and product ex-ergy values, while the minimum irreversibility is found for the turbine. Maximum improvementpotential rate is found for the combustion chamber (5141.27 kW), while minimum rate is deter-mined for the turbine of system (6.95 kW). Also, the turbine component has the highest exergyefficiency (97.20%) due to its expansion process, while combustion chamber component hasthe lowest exergy efficiency (55.39%) due to low efficient combustion process of the fuel.Furthermore, the mexogenous exergy destructions from maximum to minimum are found for the combustion chamber, air compressor and gas turbine units, respectively. Considering exergydynamic analysis, the mexogenous exergy destruction rates of the combustion chamber, aircompressor and gas turbine are found as 184.4 kW, 103.97 kW and 9.99 kW, respectively.Considering all results, the combustion chamber is the primer component to be handled for bet-ter efficiency and improvement.展开更多
文摘Current portable power generators are mainly based on internal combustion engine since they present higher values of efficiency comparing to other engines;the main reason why internal combustion engine is not convenient for micro power generation (5 - 30 kW) is because of their heaviness. Micro and ultra micro gas turbine devices, based on a micro compressor and a micro turbine installed on the same shaft, are more suitable for this scope for several reasons. Micro turbine systems have many advantages over reciprocating engine generators, such as higher power density (with respect to size and weight), extremely low emissions and few, or just one, moving part. Those designed with foil bearings and air-cooling operate without oil, coolants or other hazardous materials. Micro turbines also have the advantage of having the majority of their waste heat contained in their relatively high temperature exhaust. Micro turbines offer several potential advantages compared to other technologies for small-scale power generation, including: a small number of moving parts, compact size, lightweight, greater efficiency, lower emissions, lower electricity costs, and opportunities to utilize waste fuels. The object of this study is the experimental tests on a stand-alone gas turbine device with a pre-heated combustion chamber (CC), to validate the fuel consumption reduction, compared to an actual and commercial device, used on air models.
文摘Expanding the fuel flexibility of continuous combustion systems to include multiphase fuel combustion offers additional support to combat the problem of energy security and,potentially,environmental pollution.In this study,apart from establishing stability limits and measuring post-combustion emissions,flames generated from simultaneous combustion of biodiesel and syngas were examined using C_(2)*and CH*chemiluminescence imaging to capture changes in the reaction zone.The proportion of syngas in the fuel mix was varied from 0 to 30%content(by energy contribution)while maintaining a total power output of 15 kW.The overall equivalence ratio was held at 0.7 in cases other than for determining the flammability range.The results indicate a reduction of stability limits as gas proportion in fuel blend increases.Also,chemiluminescence imaging of the two targeted species suggest a general reduction in reaction rate as well as reaction zone area and length with increase in gas ratio in the dual phase tests.Furthermore,emissions performance in the context of NOxand CO was investigated as liquid-to-gas ratios were altered.Conclusively,the study demonstrates the feasibility,limitations and potential benefits of multiphase renewable fuel combustion in a swirl-stabilised burner.
基金the National Natural Science Foundation of China(Grant Nos.91641202 and 501100001809)the Program of Shanghai Subject Chief Scientist(Grant No.19XD1401800)。
文摘Effects of liquid fuel composition variations on characteristics of self-excited thermo-acoustic instabilities in a lean premixed,pre-vaporized gas turbine model combustor were experimentally studied.Test fuels included practical RP-3 jet fuel and its blending with iso-octane and n-dodecane,which were branched and linear alkanes respectively.Under the test conditions,dynamic pressure measurements indicated that the dominant instability frequency was highest for RP-3 flame,while RP-3/ndodecane flame exhibited the strongest instability strength.A further analysis showed that the instability frequency correlated well with the profiles of adiabatic flame temperature,and the strength of the instability highly depended on the ignition delay times of the fuels.Measurements of the flame structure and flow field with OH*chemiluminescence (CL) imaging and twodimensional particle image velocimetry (PIV) techniques indicated that changes in the fuel composition did not alter the unstable modes and general sequences of flame-flow structure oscillations.Further power spectra and proper orthogonal decomposition(POD) analysis suggested that axial oscillations along with precessing vortex core (PVC) induced helical motion predominated periodic flame structure and flow field oscillations.
文摘Strong restrictions on emissions from marine power plants(particularly SOx,NOx)will probably be adopted in the near future.In this paper,a combined solid oxide fuel cell(SOFC)and steam turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector.The analyzed variant of the combined cycle includes a SOFC operated with natural gas fuel and a steam turbine with a single-pressure waste heat boiler.The calculations were performed for two types of tubular and planar SOFCs,each with an output power of 18 MW.This paper includes a detailed energy analysis of the combined system.Mass and energy balances are performed not only for the whole plant but also for each component in order to evaluate the thermal efficiency of the combined cycle.In addition,the effects of using natural gas as a fuel on the fuel cell voltage and performance are investigated.It has been found that a high overall efficiency approaching 60%may be achieved with an optimum configuration using the SOFC system.The hybrid system would also reduce emissions,fuel consumption,and improve the total system efficiency.
文摘One of the main challenges of biogas and syngas use as fuel in hybrid solid oxide fuel cell （SOFC） cycles is the variable nature of their composition, which may cause significant changes in plant performance. On the other hand, hydrogen is one of the main components in some types of gasified biomass and syngas. Therefore, it is vital to investigate the influences of hydrogen fraction in inlet fuel on the cycle performance. In this work, a steady-state simulation of a hybrid tubular SOFC-gas turbine （GT） cycle is first presented with two configurations： system with and without anode exhaust recirculation. Then, the results of the model when fueled by syngas, biofuel, and gasified biomass are analyzed, and significant dependency of system operational parameters on the inlet fuel composition are investigated. The analysis of impacts of hydrogen concentration in the inlet fuel on the performance of a hybrid tubular SOFC and gas turbine cycle was carried out. The simulation results were considered when the system was fueled by pure methane as a reference case. Then, the performance of the hybrid SOFC-GT system when methane was partially replaced by H2 from a concentration of 0% to 95% with an increment of 5% at each step was investigated. The system performance was monitored by investigating parameters like temperature and flow rate of streams in different locations of the cycle; SOFC and system thermal efficiency; SOFC, GT, and cycle net and specific work; air to fuel ratio; as well as air and fuel mass flow rate. The results of the sensitivity analysis demonstrate that hydrogen concentration has significant effects on the system operational parameters, such as efficiency and specific work.
基金supported by the Science and Technology Commission of Shanghai Municipality(20dz1204902).
文摘As the only controllable means of a micro gas turbine(MGT)combustor during unit operation,pilot fuel ratio(PFR)is the key to achieving stable combustion and low pollutant emission.This paper discusses the influence of PFR on the inner flow field structure and pollutant emissions.The steady-state three-dimensional RANS method with a 40-step reduced methane-air kinetics mechanism is used to study the reaction flow field and species field with PFR of 9.0%,12.7%,15.2%and 17.6%.Results show that,with the decrease in PFR,the axial velocity and temperature near the central axis of the combustion chamber show a tendency to decrease.A similar separation phenomenon occurred in the core pyrolysis reaction zone(measured by HCO)and oxidation zone(measured by OH),which is more conducive to promoting the oxidation of CO.The quantitative effect of the pilot flame on nitrogen oxides(NO_(x))was separated by using inert gas instead of nitrogen in combustion air.It was found that the NOx produced by the pilot flame under the operation condition with a PFR of 9.0%was 3.2×10^(−6),accounting for 17.4%of the total NOx emission,which was twice that of PFR.
文摘In efforts to overcome an foreseeable energy crisis predicated on limited oil and gas supplies, reserves; economic variations facing the world, and of course the environmental side effects of fossil fuels, an urgent need for energy sources that provide sustainable, safe and economic supplies for the world is imperative. The current fossil fuel energy system must be improved to ensure a better and cleaner transportation future for the world. Despite the fact that the marine transportation sector consumes only 5% of global petroleum production; it is responsible for 15% of the world NOx and SOx emissions. These figures must be the engine that powers the scientific research worldwide to develop new solutions for a very old energy problem. In this paper, the most effective types of marine power plants were discussed. The history of the development of each type was presented first and the technical aspects were discussed second. Also, the fuel ceils as a new type of power plants used in marine sector were briefed to give a complete overview of the past, present and future of the marine power plants development. Based on the increased worldwide concerns regarding harmful emissions, many researchers have introduced solutions to this problem, including the adoption of new cleaner fuels. This paper was guided using the same trend and by implementing the hydrogen as fuel for marine internal combustion engine, gas turbines, and fuel cells.
文摘Qatar energy consumptions are among the highest in the world, and can easily serve double the present population. Energy conservation is a must, as the energy resources are finite, and their consumptions are increasing at alarming rates. The country depends on desalted seawater, which consumes extensive amounts of energy, and is produced by using the least energy efficient desalting system. The desalination process is vulnerable to many factors, and strategic water storage needs to be built. The high energy consumptions are ruining the air and marine environments. Several suggestions are introduced to conserve energy in the Cogeneration Power Desalting Plants (CPDP), by moving to replace the Multi Stage Flash (MSF) desalting system by the energy efficient Seawater Reverse Osmosis System (SWRO);fully utilizing the installed power capacity to desalt water in winter, when electric power load is low, and during summer non-peak hours for strategic water storage;and modifying the simple Gas Turbines (GT) Power cycle plants to GT combined cycle to raise the Electric Power (EP) generation efficiency (to about 50%).
文摘In this study, exergy dynamic and advanced exergy analyses are applied to theturbojet engine to assess its mexogenous, endogenous, exogenous, avoidable and unavoidableexergies under the environment conditions of 15 C temperature and 1 bar pressure. Themaximum exergy point in the turbojet engine is found for the combustor in which C11H23(Jet-A1) fuel is combusted with air, while the minimum one is determined for the aircompressor head where the free air enters. The combustion chamber has the maximum fuel,product and irreversibility rates and the air compressor has the minimum fuel and product ex-ergy values, while the minimum irreversibility is found for the turbine. Maximum improvementpotential rate is found for the combustion chamber (5141.27 kW), while minimum rate is deter-mined for the turbine of system (6.95 kW). Also, the turbine component has the highest exergyefficiency (97.20%) due to its expansion process, while combustion chamber component hasthe lowest exergy efficiency (55.39%) due to low efficient combustion process of the fuel.Furthermore, the mexogenous exergy destructions from maximum to minimum are found for the combustion chamber, air compressor and gas turbine units, respectively. Considering exergydynamic analysis, the mexogenous exergy destruction rates of the combustion chamber, aircompressor and gas turbine are found as 184.4 kW, 103.97 kW and 9.99 kW, respectively.Considering all results, the combustion chamber is the primer component to be handled for bet-ter efficiency and improvement.
