Effect Of Turbine Inlet Temperature Research Articles

Turbine inlet temperature effects on the start process of an expansion cycle liquid propellant rocket engine

The main objective of this study is to investigate the effect of turbine inlet temperature on the transient phase of expansion cycle liquid propellant rocket engines during start. For this purpose, the non-linear differential mathematical model for 15 main components of the engine is derived, and the corresponding interaction between them is established. Afterward, the model is simulated using MATLAB Simulink, and 150 equations are solved with the Newton–Raphson method. The RL10 expansion cycle liquid propellant rocket engine is selected as a case study, and its dynamic behavior is simulated, and the results are compared with the experimental data. The simulation results showed that the present model for engine dynamic parameters, including thrust-chamber pressure, fuel, oxidizer mass flow rate, and turbo-pump speed, has less than 5% error compared to previous literatures. Using the prepared modeling software, the effect of turbine inlet temperature is studied on the engine start process. The obtained results demonstrated that inappropriate temperature profile during start transient might cause an engine malfunction while entering the nominal working regime.

Thermodynamics of CMC bladed marine gas turbine-LM 2500: Effect of cycle operating parameters

Recent developments in ceramic-matrix composites and their successful use in combustor liners and shrouds have generated interest among researchers to adopt these materials in rotating gas turbine blades, especially in the first stages of high-pressure turbines where gas temperatures are highest. CMC blades have the potential of being retrofitted to replace superalloy turbine blades in operating gas turbines. In this paper, a comparative study on the thermodynamic performance of a marine gas turbine engine, LM 2500, featuring directionally solidified nickel superalloy blades versus novel CMC blades in the high-pressure turbine sections has been reported. Mathematical modeling of the gas turbine cycle components has been developed and then coded in C++ language. The effects of turbine inlet temperature on thermodynamic efficiencies, coolant mass flow rates, and work ratios on the two systems have been analyzed. Finally, the exergy analysis of the systems’ components has been done to identify the benefits of adopting CMC blades in the LM 2500 system. It has been observed that when compared to the directionally solidified bladed turbine system, the projected first law efficiency of CMC bladed LM 2500 gas turbines can be enhanced over 7% (from 34.17% to 41.21%). The projected work ratio can be improved by over 16% (from 0.49 to 0.57) at the turbine inlet temperature of 1725 K.

Thermodynamic analysis of a comprehensive energy utilization system for natural gas pressure reduction stations based on Allam cycle

• A comprehensive energy utilization system for natural gas pressure reduction stations based on Allam cycle is proposed. • The effects of key parameters on the proposed system performance are clarified. • The proposed system and the pre-heating system are compared and analyzed. • Energy efficiency is 99.31% with turbine inlet parameters of 30 MPa/900 °C. In order to effectively utilize the pressure energy and cold energy of the natural gas pressure reduction stations, this paper proposes a comprehensive energy utilization system for natural gas pressure reduction stations based on Allam cycle. The low-grade waste heat during the Allam cycle and ambient heat are used to heat the decompressed natural gas to the temperature required by the user. Based on the established mathematical model, the effects of turbine inlet temperature, turbine inlet pressure, turbine outlet pressure, isentropic efficiency of power equipment, and natural gas expansion stages on the performance of the proposed system are studied. The proposed system and the pre-heating system are compared and analyzed. The results show that when the combustor outlet temperature is 900℃, the energy efficiency and incremental efficiency of the proposed system are 99.31% and 103.55%, respectively. Compared with pre-heating system based on gas turbine cycle, they have increased by 9.84 percentage points and 19.32 percentage points, respectively. Compared with the boiler-based post-heating system, the energy efficiency is increased by 3.5 percentage points.

Presenting a power and cascade cooling cycle driven using solar energy and natural gas

A configuration is presented where solar energy is parallel with fossil fuel to steadily supply a combined power and cascade cooling system. The cascade cooling system produces a steady cooling load at shallow temperatures. The variations of solar radiation during a year are considered. The system combines an improved ammonia-water power cycle with an absorption-compression cascade refrigeration system. The exhaust from the power cycle drives the absorption chiller. Working fluids are ammonia-water for absorption and power cycles and R134a for compression chiller. The effects of turbine inlet temperature, the ammonia concentration in the power cycle, boiler pressure, and generator temperature are investigated. Considering the cooling section's exergy efficiency, the generator temperature is optimized at 110.5 °C. The power cycle's boiler pressure and ammonia concentration are optimized using a genetic algorithm for various cooling loads at various turbine inlet temperature values to find the maximum annual exergy efficiency. The results show that, in all investigated cooling loads, the maximum annual exergy efficiency with a mean value of 65.66% happens at the turbine inlet temperature of 210 °C, an average boiler pressure of 58.56 bar, and an average ammonia concentration of 81.16%.

A newly proposed supercritical carbon dioxide Brayton cycle configuration to enhance energy sources integration capability

A new cycle layout for the supercritical carbon dioxide with its better integration capabilities with heat sources for increased temperature difference across the receiver has been proposed and analyzed in the current study. Design point analysis of the proposed cycle layout and the available cycle layouts in literature, i.e., regenerative, recompression, intercooling, and partial cooling cycles, have been performed and compared. Moreover, the effect of turbine inlet temperature, compressor's inlet pressure, and compressor inlet temperature on the cycle's efficiency, specific work, and integration capabilities with heat source have been studied for all the cycle layouts, including the proposed cycle layout. Results suggest that the proposed cycle's configuration exhibits better integration capabilities than other cycle layouts studied in this work contributing to cost-effective power generation. The cycle's efficiency for the current cycle is comparable with the intercooling cycle, where the specific work value for the proposed process is found maximum among all the cycles. Further, the UA values for the proposed cycle are found up to 33% smaller than the intercooling cycle.

Efficiency Enhancement of Solar Thermal Power Systems Introduction of Secondary Brayton Cycle with Supercritical CO2/C2H6

An improvement of supercritical carbon dioxide Brayton cycle with regeneration coupled with a (carbon dioxide/ethane) shielded as a second cycle before starting the cooling phase in a solar tower installation was carried out. The power block unit in the cycle, as mentioned above designed to produce 160 MWe in the Ouarzazate region, where a gigantic solar project conducted in Morocco with a design point DNI evaluated as 823 W/m2. So, the aim to compare the performance of the s-ethane against the s-CO2, operating in the secondary cycle, two critical parameters studied are, the first one is the effect of turbine inlet temperature on net power. And the second one is the effect of secondary Brayton cycle pressure on the system efficiency. The cycle efficiency, founded to be 58% at high turbine inlet temperature by including an aided s-ethane cycle. The research work is in progress. In perspectives, specific other possible configurations and other trans-critical fluids will address in the secondary Brayton cycle.

Off-Design Analysis of a Supercritical CO2 Brayton Cycle with Ambient Air as the Cold Source Driven by Waste Heat from Gas Turbine

Utilizing energy efficiently could greatly relieve current energy crisis. Therefore, in this article, a simple supercritical CO2 Brayton cycle for waste heat recovery from gas turbine is presented. The system uses ambient air as its cold source, which is more convenient and economic. Considering temperature difference between heat source and turbine inlet, it is of great significance to research the effects of turbine inlet temperature on the system performance due to the high temperature range of the exhaust gas from gas turbine. For this purpose, a control strategy is proposed and a mathematical model is established on off-design conditions to predict system performance when turbine inlet temperature increases from 673.15 K to 773.15 K. Results indicate that both turbine power output and system net power output increase with the rise of turbine inlet temperature, as well as total heat transfer in heater and cooler. Furthermore, the system thermal efficiency also increases until it becomes maximum on design point. In addition, the efficiency of turbomachinery varies slightly.

First and Second Law Analysis of Supercritical CO2 Recompression Brayton Cycle

The present research concentrates on the energy and exergy analysis of the S-CO2 recompression Brayton cycle and the individual components irreversibilities by varying the different operating parameters. Results show that the cycle efficiencies and LTR effectiveness reduce by increasing minimum cycle temperature, but HTR increases. The effect of minimum cycle temperature is more critical on cycle performance than maximum cycle temperature. The reactor has the highest irreversibility followed by recuperators and pre-cooler. Exergy efficiency shows a downward trend as environment temperature enhances. However, the effect of turbine inlet temperature is very low on-cycle efficiency and optimum pressure ratio for lower compressor outlet pressure values, which is more significant by increasing this parameter.

Parametrized Analysis and Multi-Objective Optimization of Supercritical CO2 (S-CO2) Power Cycles Coupled with Parabolic Trough Collectors

Supercritical CO2 (S-CO2) Brayton cycles have become an effective way in utilizing solar energy, considering their advantages. The presented research discusses a parametrized analysis and systematic comparison of three S-CO2 power cycles coupled with parabolic trough collectors. The effects of turbine inlet temperature and pressure, compressor inlet temperature, and pressure on specific work, overall efficiency, and cost of core equipment of different S-CO2 Brayton cycles are discussed. Then, the two performance criteria, including specific work and cost of core equipment, are compared, simultaneously, between different S-CO2 cycle layouts after gaining the Pareto sets from multi-objective optimizations using genetic algorithm. The results suggest that the simple recuperation cycle layout shows more excellent performance than the intercooling cycle layout and the recompression cycle layout in terms of cost, while the advantage in specific work of the intercooling cycle layout and the recompression cycle layout is not obvious. This study can be useful in selecting cycle layout using solar energy by the parabolic trough solar collector when there are requirements for the specific work and the cost of core equipment. Moreover, high turbine inlet temperature is recommended for the S-CO2 Brayton cycle using solar energy.

Energetic and exergetic performance analysis of a solar driven power, desalination and cooling poly-generation system

This paper presents a thermodynamic analysis of a poly-generation system powered by solar thermal energy using parabolic trough collectors. The proposed system consists of an organic Rankine cycle, a multiple effect distillation and an absorption cooling unit. The performance analysis of the solar system is conducted for different configurations: power generation only, cogeneration power and cooling, cogeneration power and desalination, and poly-generation. The effects of turbine inlet temperature and pump inlet temperature on the energetic and exergetic system performance as well as the net power output and total exergy loss of the system are examined. In addition, exergetic parameters, including system total exergy loss, fuel depletion ratio and improvement potential were analyzed. The study reveals that increasing the turbine inlet temperature increases the performance while it reduces the total exergy destruction rate of the system. The result of the study also shows that the two main sources of exergy destruction are the solar thermal collector and desalination unit; with 49.3% of the input exergy (76% of the total exergy loss) destructed in the collector while 9.6% of the inlet exergy (14.9% of the total exergy loss) is destroyed in the desalination system. The overall improvement potential of the system was found to be 64.8%.

Study on the Effect of Turbine Inlet Temperature and Backpressure Conditions on Reduced Turbine Flow Rate Performance Characteristics and Correction Method for Automotive Turbocharger

In actual vehicle operation, the turbocharger turbine operates at various temperatures, inlet, and backpressure conditions, unlike compressors. The flow rate characteristics of the turbine are generally evaluated under certain conditions using an assembled turbocharger with a compressor and a turbine and a hot gas bench from the turbocharger manufacturer. Flow rate characteristics are also presented as the reduced mass flow rate to correct the flow rate characteristics according to the turbine inlet temperature and pressure. Therefore, the turbine mass flow rate seen in many engine development cases and studies—including the analysis of the turbine performance and characteristics, engine model configuration, and matching of the engine and turbocharger—is calculated according to the reduced turbine mass flow rate performance and turbine inlet temperature and pressure obtained through hot gas bench experiments under certain conditions. However, the performance of the reduced turbine mass flow rate is influenced by the compressor power conditions, and additional correction of the reduced turbine mass flow rate is required when the turbine inlet temperature and turbine backpressure differ from the reference test conditions, such as the hot gas bench test conditions. In this study, the effect of the turbine inlet temperature and turbine backpressure on the performance of the reduced turbine mass flow rate were examined based on the power balance relationship between the compressor and turbine of an automotive turbocharger. The principle of its correction is also presented.

Mass optimization of a supercritical CO2 Brayton cycle with a direct cooled nuclear reactor for space surface power

A long life, reliable, and compact surface power system will be necessary to achieve future goals in space exploration. This application uniquely requires the system to be optimized with respect to mass because system mass directly drives the space launch cost associated with transporting the system to its desired location. In this study, a supercritical CO2 Brayton cycle coupled to a direct-cooled nuclear reactor was designed and optimized for mass. Robust models were developed for each Brayton cycle component in order to model the cycle performance. The three most massive components of this cycle are the radiator-based heat rejection system (subsequently referred to as the “radiator”), recuperator, and reactor. Mass correlations for the recuperator and radiator were established through interactions with component experts from industry and national labs. A reactor model was developed to predict the minimum mass reactor that satisfies neutronic and thermal limitations for given cycle conditions. The system optimization explores tradeoffs between the reactor, recuperator, and radiator sizes in order to identify the least massive system that will satisfy the power (40 kWe) and life (10 yr) requirements. To explore the effects of turbine inlet temperature on system mass, three types of microtube and shell recuperator technologies were considered: baseline stainless steel (which is consistent with the industry partner’s current designs), stainless steel with non-heritage tube sizes (which requires further development of manufacturing techniques), and Inconel (which is not a current/legacy design). Both stainless steel designs have a temperature limit of 823 K, which limits the turbine inlet temperature to 900 K. The baseline stainless steel design results in a combined mass of 738 kg. The stainless steel design allowing for non-heritage tube sizes reduces the combined mass to 674 kg (a 9% improvement). The Inconel design leads to an optimal turbine inlet temperature of 1120 K and reduces the combined mass to 391 kg (a 47% improvement). Interesting conclusion from this study include: (1) radiator mass dominates the total mass, and this drives the cycle to relatively high heat rejection temperatures resulting in a compressor inlet state point that is not close to the vapor dome; thus, the typical advantages of an sCO2 system are not realized, and a working fluid with a higher critical temperature may be more suitable, and (2) neutronic limitations cause the reactor size to be relatively unaffected by the power level.

Innovative thermodynamic parametric investigation of gas and steam bottoming cycles with heat exchanger and heat recovery steam generator: Energy and exergy analysis

In this study, gas and steam bottoming cycles, driven by the exhaust gas of Gas turbine cycle, are analyzed thermodynamically. The waste heat of the Gas turbine topping cycle (GT) exhaust gas is used partially to heat the air in the air bottoming cycle and partially to generate steam by passing it through HRSG in the steam bottoming cycle. The topping Gas turbine and air bottoming cycles are coupled with the heat exchanger, whereas the topping and steam bottoming cycles are coupled with Heat Recovery Steam Generator (HRSG). The effects of turbine inlet temperature (1100 K ⩽ TIT ⩽ 1500 K), pressure ratio (6⩽rpt⩽12) and flow rate of exhaust gas on the Net work and combined thermal efficiency and exergy loss of exhaust gas are investigated. It is observed that the Net work of steam bottoming cycle is higher than the Net work of gas bottoming cycle and for higher values of turbine inlet temperature TIT = 1500 K, 90% of power is recovered through the bottoming cycle at lower pressure ratio. The combined thermal efficiency increases by 10% with an increase in the turbine inlet temperature from 1100 to 1500 K. It is found that the combined thermal efficiency increases with all pertinent parameters.

Integration of chemical looping combustion and supercritical CO2 cycle for combined heat and power generation with CO2 capture

Chemical looping combustion (CLC) is an emerging technology for energy conversion with inherent CO2 separation. Supercritical CO2 (sCO2) Brayton cycle is a promising way for efficient power production with compactness. In this work, CLC and sCO2 cycle were integrated for combined heat and power (CHP) cogeneration with CO2 capture. Coal was directly used as fuel for CLC, and CLC acted as heat source to drive a sCO2 cycle with reheating and recompression. The heat in sCO2 cooling and CO2 compression processes was recovered for district heating. A comprehensive analysis with first law based efficiency was performed to investigate the performance of the proposed cycle. For a baseline case of the proposed configuration, the net power efficiency was 41.3%, the heating efficiency was 40.4% and the resulting total efficiency was 81.7%, including CO2 compression to 120 bar. The effects of turbine inlet temperature, turbine inlet pressure, fuel reactor temperature, air reactor temperature, oxygen carrier ratio, inert support ratio, and air ratio on the thermal performance, including net power efficiency, heating efficiency, and total efficiency were analyzed as well.

Influence of Different Steam Cooling Techniques for High Pressure Turbine Blades on the Performance of Gas Turbine

Gas turbines are always intended to give more specific work output for which continuous exposure to hot combustion gases is necessary. To increase the lifespan of the turbine blades active cooling should be applied to the High Pressure (HP) turbine blades. In the present work, a simple open cycle gas turbine is modeled to carry out thermodynamic analysis with different open loop steam cooling techniques: steam internal convection cooling (SICC), steam film cooling (SFC) and steam transpiration (STC) cooling. The effect of Turbine inlet temperature (TIT), Turbine blade temperature (T_b), and Compressor pressure ratio (CPR) on the coolant flow requirement and effect of T_b on the performance are estimated. The entire analysis is carried out with contemplation of variable specific heat (VSH) along with constant specific heats (CSH) for air and gas. Between VSH and CSH approaches, the former analysis leads to better performance from the first and second law efficiencies point of view. Irreversibility and Entropy generation rate are maximum in the combustor and they are less for VSH case in all cooling schemes and are decreased by 38.53%, 40.01%, and 40.40% for SICC, SFC and STC schemes respectively when compared with CSH(at TIT=1580 K, T_b=1123 K, CPR=19.1) analysis.

Thermodynamic analysis and comparison for different direct-heated supercritical CO2 Brayton cycles integrated into a solar thermal power tower system

In this paper, a complete mathematical model is developed to carry out the thermodynamic analysis and comparison for different direct-heated S-CO2 Brayton cycles (simple, pre-compression, recompression, partial-cooling, and intercooling) integrated into a solar power tower (SPT) system. Based on the model, the effect of turbine inlet temperature (TIT) on the thermodynamic performances of the receiver, the thermal energy storage unit, the S-CO2 power cycle blocks and the integrated SPT systems is investigated respectively for these cycles. Additionally, a comparison of cycle efficiencies and overall integrated SPT system efficiencies is performed for five S-CO2 cycles at a series of total recuperator conductance (UAtotal) values. The results reveal that the TIT exhibits a parabolic effect on the overall efficiencies for each S-CO2 cycle, and the intercooling S-CO2 cycle achieves the highest overall efficiencies followed by the recompression, the partial-cooling, the pre-compression, and the simple cycles at different TIT values. Furthermore, the partial-cooling cycle possesses the highest overall specific work at each TIT and offers higher overall efficiencies than the recompression cycle at a constant TIT (650 °C) as the UAtotal is rather low, having the potential to reduce the costs of integrated SPT systems with limited UAtotal values.

Thermodynamic analysis of KCS/ORC integrated power generation system with LNG cold energy exploitation and CO2 capture

In this paper, an integrated power generation system of Kalina cycle system (KCS) and organic Rankine cycle (ORC) with LNG cold energy exploitation and CO2 capture is introduced. The composite circulation system can fully recover and use the medium and low temperature waste heat to reduce the greenhouse gas emissions. To evaluate the system performances, the thermodynamics model was established and the system was simulated by using Aspen HYSYS software. Thermodynamic analysis has been performed to study the effects of turbine inlet temperature, NH3 mass fraction, evaporation pressure and CO2 capture pressure on the KCS/ORC integrated system. The optimal conditions were also investigated and identified. Exergy analysis of the components operated on KCS or ORC has also been demonstrated. The results showed that the optimal values of the network output, thermal efficiency and CO2 captured quantity of the system were respectively 394.685 kW, 53.25% and 0.3 t/tCO2 (0.6 t/tLNG), while the evaluation indexes of the power recovery efficiency and exergy efficiency were respectively 36% and 41.42%. The exergy loss efficiency of each component was examined. It was indicated that the whole system has significant advantages in waste heat recovery.

Conceptual Design and Performance Analysis of SOFC/Micro Gas Turbine Hybrid Distributed Energy System

A numerical model has been developed for the performance analysis of solid oxide fuel cell (SOFC)/micro gas turbine (MGT) hybrid systems with prereforming of natural gas, in which a quasi two-dimensional model has been built up to simulate the cell electrochemical reaction, heat and mass transfer within tubular SOFC. The developed model can be used not only to predict the overall performance of the SOFC/MGT hybrid system but also to reveal the nonuniform temperature distribution within SOFC unit. The effects of turbine inlet temperature (TIT) and pressure ratio (PR) on the performance of the hybrid system have been investigated. The results show that selecting smaller TIT or PR value will lead to relative higher system efficiency and lower CO2 emission ratio; however, this will raise the risk to destroy SOFC beyond the limitation temperature of electrolyte.

Exergy-based thermodynamic analysis of solar driven Organic Rankine Cycle

In this paper thermodynamic modeling of organic Rankine cycle (ORC) driven by parabolic trough solar collectors is presented. Eight working fluids for the ORC were examined. The effect of turbine inlet temperature on main energetic and exergetic performance parameters were studied. The influences of turbine inlet temperature on turbine size parameter, turbine outlet volume flow rate and expansion ratio were also investigated. Important exergetic parameters including irreversibility ratio and total exergy destruction rate were also included in the analysis and evaluated. The study reveals that increasing the turbine inlet temperature results in increasing the net electric efficiency, net power output, exergy efficiency and expansion ratio while the total exergy destruction rate and turbine size parameter are reduced. From the considered working fluids, o-xylene gives the best energetic and exergetic performance. The results of the study also show that the main source of exergy destruction occurs in the solar collector where 74.9% of the total exergy loss is destructed. Next to collectors, 18.2% of the total destructed exergy occurs in the condenser

Thermodynamic and economic performances optimization of an organic Rankine cycle system utilizing exhaust gas of a large marine diesel engine

Abstract The aim of this study is to investigate the thermodynamic and economic performances optimization for an ORC system recovering the waste heat of exhaust gas from a large marine diesel engine of the merchant ship. Parameters of net power output index and thermal efficiency are used to represent the economic and thermodynamic performances, respectively. The maximum net power output index and thermal efficiency are obtained and the corresponding turbine inlet pressure, turbine outlet pressure, and effectiveness of pre-heater of the ORC system are also evaluated using R1234ze, R245fa, R600, and R600a. Furthermore, the analyses of the effects of turbine inlet temperature and cooling water temperature on the optimal economic and thermodynamic performances of the ORC system are carried out. The results show that R245fa performs the most satisfactorily followed by R600, R600a, and R1234ze under optimal economic performance. However, in the optimal thermodynamic performance evaluations, R1234ze has the largest thermal efficiency followed by R600a, R245fa, and R600. The payback periods will decrease from 0.5 year for R245fa to 0.65 year for R1234ze respectively as the system is equipped with a pre-heater. In addition, compared with conventional diesel oil feeding, the proposed ORC system can reduce 76% CO2 emission per kilowatt-hour.