This document discusses the thermodynamics of axial compressors and turbines used in gas turbines. It provides an overview of the Brayton cycle and discusses how to calculate the shaft power required for compression, temperature rises in the compressor, and outlet temperature as a function of pressure ratio, inlet temperature, and isentropic efficiency. Higher compression ratios are desirable because they increase turbine efficiency and overall gas turbine efficiency, though the rate of efficiency improvement decreases at higher ratios. Designing high-efficiency machines requires balancing increased efficiency from high compression against diminishing returns.
The document summarizes the key components and functioning of a gas turbine combustion chamber. It describes the combustion chamber, diffuser, liner, snout, dome, and swirler. The combustion chamber must stabilize flames in a continuous high-velocity air flow. It utilizes techniques like bluff bodies or swirl to generate recirculation zones for ignition and flame anchoring. The liner must withstand high temperatures and is cooled using film or transpiration cooling techniques.
A centrifugal compressor operates by using a rotating impeller to impart kinetic energy to a fluid and increase its pressure. It has three main components: an impeller, diffuser, and volute casing. The impeller accelerates the fluid radially outward via centrifugal force. The diffuser converts the fluid's kinetic energy to pressure. Common types of impellers include backward-curved, forward-curved, and radial blades. Performance is affected by factors like impeller shape, slip factor, choking, and pressure ratio. Characteristic curves show the compressor's operating range in terms of pressure ratio and relative flow.
The document discusses performance assessment of compressors through field testing. It describes methods to measure free air delivery, isothermal power, volumetric efficiency and specific power requirement. The nozzle method and pump up method are explained to measure free air delivery. Calculations are provided as examples to determine isothermal efficiency and specific power consumption. Periodic performance assessment is important to minimize compressed air costs and improve system efficiencies.
The document summarizes key concepts about thermodynamics cycles. It describes the processes that make up the Otto cycle used in spark-ignition engines, including isentropic compression, constant volume heat addition, isentropic expansion, and constant volume heat rejection. The thermal efficiency of the Otto cycle is defined. An example calculation illustrates determining temperatures, pressures, thermal efficiency, back work ratio, and mean effective pressure for an Otto cycle. The Diesel cycle used in compression ignition engines is also introduced.
The document discusses different types of gas turbine cycles including direct open, indirect open, direct closed, and indirect closed cycles. It then focuses on the ideal Brayton cycle and how the net work output varies with pressure ratio, reaching a maximum at a specific pressure ratio. The regenerative Brayton cycle is introduced as an improvement where heat is recouped through a regenerator. Intercooling and reheating are also discussed as ways to further improve the cycle performance. Combined cycles, which use both gas and steam turbines, provide higher efficiencies than gas turbines alone. The ideal jet propulsion cycle for aircraft is described, where the turbine power is only used to drive the compressor.
This document contains 39 multiple choice questions related to thermodynamics concepts such as power, heat transfer, enthalpy, entropy, ideal gases, and thermodynamic processes. The questions assess understanding of key equations, properties of substances, and calculations involving changes in temperature, pressure, volume, and other thermodynamic variables.
The properties of a gas mixture depend on the properties of its individual components and their relative amounts. There are two ways to describe the composition of a mixture: molar analysis specifies the moles of each component, and gravimetric analysis specifies the mass of each component. For ideal gas mixtures, Dalton's law and Amagat's law can be used to determine pressure and volume behavior. For real gas mixtures, these laws are approximate and equations of state must be used. The properties of gas mixtures can be determined by weighted averages of the component properties.
Separating and throttling calorimeter for steamSaif al-din ali
This document describes an experiment conducted to determine the quality (dryness fraction) of steam passing through a steam main using a separating and throttling calorimeter setup. The calorimeter was developed on a diesel-fired boiler in a thermal power laboratory. The experiment measured parameters like steam temperature, pressure, and flow rates. Steam was sampled from the main and passed through a separator to remove water, then throttled to a lower pressure and superheated region where its dryness fraction could be calculated using energy equations and steam tables. Factors affecting the accuracy of the experiment like measurement errors and device leaks were also discussed.
The document summarizes the key components and functioning of a gas turbine combustion chamber. It describes the combustion chamber, diffuser, liner, snout, dome, and swirler. The combustion chamber must stabilize flames in a continuous high-velocity air flow. It utilizes techniques like bluff bodies or swirl to generate recirculation zones for ignition and flame anchoring. The liner must withstand high temperatures and is cooled using film or transpiration cooling techniques.
A centrifugal compressor operates by using a rotating impeller to impart kinetic energy to a fluid and increase its pressure. It has three main components: an impeller, diffuser, and volute casing. The impeller accelerates the fluid radially outward via centrifugal force. The diffuser converts the fluid's kinetic energy to pressure. Common types of impellers include backward-curved, forward-curved, and radial blades. Performance is affected by factors like impeller shape, slip factor, choking, and pressure ratio. Characteristic curves show the compressor's operating range in terms of pressure ratio and relative flow.
The document discusses performance assessment of compressors through field testing. It describes methods to measure free air delivery, isothermal power, volumetric efficiency and specific power requirement. The nozzle method and pump up method are explained to measure free air delivery. Calculations are provided as examples to determine isothermal efficiency and specific power consumption. Periodic performance assessment is important to minimize compressed air costs and improve system efficiencies.
The document summarizes key concepts about thermodynamics cycles. It describes the processes that make up the Otto cycle used in spark-ignition engines, including isentropic compression, constant volume heat addition, isentropic expansion, and constant volume heat rejection. The thermal efficiency of the Otto cycle is defined. An example calculation illustrates determining temperatures, pressures, thermal efficiency, back work ratio, and mean effective pressure for an Otto cycle. The Diesel cycle used in compression ignition engines is also introduced.
The document discusses different types of gas turbine cycles including direct open, indirect open, direct closed, and indirect closed cycles. It then focuses on the ideal Brayton cycle and how the net work output varies with pressure ratio, reaching a maximum at a specific pressure ratio. The regenerative Brayton cycle is introduced as an improvement where heat is recouped through a regenerator. Intercooling and reheating are also discussed as ways to further improve the cycle performance. Combined cycles, which use both gas and steam turbines, provide higher efficiencies than gas turbines alone. The ideal jet propulsion cycle for aircraft is described, where the turbine power is only used to drive the compressor.
This document contains 39 multiple choice questions related to thermodynamics concepts such as power, heat transfer, enthalpy, entropy, ideal gases, and thermodynamic processes. The questions assess understanding of key equations, properties of substances, and calculations involving changes in temperature, pressure, volume, and other thermodynamic variables.
The properties of a gas mixture depend on the properties of its individual components and their relative amounts. There are two ways to describe the composition of a mixture: molar analysis specifies the moles of each component, and gravimetric analysis specifies the mass of each component. For ideal gas mixtures, Dalton's law and Amagat's law can be used to determine pressure and volume behavior. For real gas mixtures, these laws are approximate and equations of state must be used. The properties of gas mixtures can be determined by weighted averages of the component properties.
Separating and throttling calorimeter for steamSaif al-din ali
This document describes an experiment conducted to determine the quality (dryness fraction) of steam passing through a steam main using a separating and throttling calorimeter setup. The calorimeter was developed on a diesel-fired boiler in a thermal power laboratory. The experiment measured parameters like steam temperature, pressure, and flow rates. Steam was sampled from the main and passed through a separator to remove water, then throttled to a lower pressure and superheated region where its dryness fraction could be calculated using energy equations and steam tables. Factors affecting the accuracy of the experiment like measurement errors and device leaks were also discussed.
Refrigeration and air conditioning (full note)shone john
Principles of refrigeration: Thermodynamics of refrigeration - Carnot cycle,
reversed carnot cycle, heat pump, and refrigerating machine- coefficient of
performance - unit of refrigeration - refrigeration methods- conventional
refrigeration systems. Air refrigeration system- Bell Coleman cycle - C.O.P.
capacity work and refrigerant flow requirements in Bell - Coleman cycle.
Module 2
Vapour compression system: simple cycle -comparison with Carnot cycle -
theoretical, actual and reactive - COP effect of operating parameters on
COP - wet, dry and superheated compression - under cooling - actual cycle
representation on TS and PH diagrams simple problems. Advanced
vapour compression systems - multistage vapour compression systems -
flash chamber multiple compression and evaporation systems cascading -
simple problems.
Module 3
Vapour absorption systems: simple, cycles - actual cycle - ammonia water
and lithium bromide water systems - COP - electrolux system. Refrigerant
and their properties: Nomenclature - suitability of refrigerants for various
applications - unconventional refrigeration methods- Vortex tube, steamjet, magnetic (cryogenics) refrigeration and thermoelectric refrigeration -
applied refrigeration house hold refrigerators - unit air conditioners andModule 4
Refrigeration system components: condensers - water and air cooled
condensers - evaporative condensers - expansion devises - capillary tubeconstant pressure expansion valve - thermostatic expansion valve - float
valve and solenoid valve - evaporators - natural convection coils - flooded
evaporators - direct expansion coils. Reciprocating compressors: single
stage and multistage compressors - work done optimum pressure ratioeffect of interfolding - volumetric efficiency -effect of clearance -
isothermal and adiabatic efficiency - compressed air motors. Rotodynamic
compressors: Screw and vane type compressors - principle of operation -
hermetic, semihermetic and open type refrigeration compressors.
Module 5
Principles of air conditioning: Psychrometry and psychrometric chart
thermodynamics of human comfort - effective temperature - comfort chart
applied psychrometry - sensible heat factor - psychometric processproblems. Winter air conditioning: heating load calculations humidifiers
and humidistat. Summer air conditioning: cooling load calculations - year
round air conditioning - unitary and central systems - principles of air
distribution - design of air duct systems.
References
1. Refrigeration and air conditioning - Ballaney P. L.
2. Refrigeration and air conditioning - Stocker W. F.
3. Refrigeration and air conditioning - Jordan and Protester
4. Principles of Refrigeration - Roy J. Dossat
Definition and Requirements
Types of Heat Exchangers
The Overall Heat Transfer Coefficient
The Convection Heat Transfer Coefficients—Forced Convection
Heat Exchanger Analysis
Heat Exchanger Design and Performance Analysis
1. The document discusses gas turbine cycles with two shafts, where one turbine drives the compressor and the other provides power output. It describes regeneration using a heat exchanger to improve efficiency by heating the compressed air. Intercooling between compression stages and reheating are also discussed to reduce the work of compression. Examples are provided to calculate efficiency, power output, temperatures and pressures at different points in regenerative cycles with variations like intercooling.
The document summarizes key aspects of steam turbines. It begins by explaining that a steam turbine converts the heat energy of steam into kinetic energy and then rotational energy to generate power. It then describes the basic Rankine cycle used in steam turbine power plants.
The main body explains the principles of operation for impulse and reaction turbines. In an impulse turbine, steam expands within nozzles and does not change pressure as it moves over blades, while in a reaction turbine steam pressure gradually drops as it expands over fixed and moving blades.
Finally, it discusses methods to improve efficiency, such as compounding and reheat, where dividing the expansion process into multiple stages separated by reheaters increases overall efficiency compared to a single stage by
The document summarizes the combustion chamber of a jet engine. It discusses how an air-fuel mixture burns inside the combustion chamber and how proper combustion and stabilization of the flame are essential for optimum engine power. It also describes the various requirements of a combustion chamber, including maintaining stable combustion over a wide range of operating conditions, high combustion efficiency, withstanding high temperatures, and minimizing pressure loss during combustion.
The document discusses combustion chamber design and types for gas turbine engines. It describes the key requirements for combustion chambers including low weight, stable and efficient combustion over operating conditions, and uniform temperature distribution. It classifies combustion chambers as can, can-annular, or annular and describes the characteristics and advantages/disadvantages of each type. Important factors for combustion chamber design are maintaining suitable turbine inlet temperatures, stable combustion over a range of operating conditions, and controlling emissions.
This document discusses the Rankine cycle, which is a thermodynamic cycle derived from the Carnot vapor power cycle. It consists of four processes: 1) Isobaric heat supply in the boiler where water is heated to high pressure steam, 2) Adiabatic expansion of the steam in a turbine to produce work, 3) Isobaric heat rejection in the condenser where the steam is condensed back to water, and 4) Adiabatic pumping of the condensate back to the boiler to complete the cycle. The heat and work transfers are also defined for each process.
Need for cooling of an aircraft. types of air-refrigeration system, DART, Advantages of air refrigeration system, Open and closed cycle air refrigeration,
This document discusses calculations of air-fuel ratios in carburators. It first describes the basic components and airflow in a simple carburator. It then presents equations for determining the theoretical mass airflow rates of both air and fuel through the carburator, taking into account factors like compressibility of air, pressure differences, temperatures and densities. The document concludes that the air-fuel ratio depends on factors like the venturi throat diameter, fuel jet diameter, pressure difference across the venturi and densities of air and fuel. It also provides an example problem solving for the air-fuel ratio of a carburator with given specifications under two conditions, neglecting and accounting for the fuel nozzle tip.
Design of machine elements - V belt, Flat belt, Flexible power transmitting e...Akram Hossain
This document provides the solution to a multi-part design problem involving the design of a belt drive system. It selects appropriate pulley sizes and belt widths using standard design procedures and tables. It calculates key parameters like belt stress, operating tensions, and initial tension. The initial tension is found to be reasonable compared to recommendations. The document also provides a recommendation to potentially redesign the system for greater economy.
The document discusses gas turbine cycles and thermodynamic cycles used in gas turbines. It begins by describing air standard cycles and assumptions made, including the working fluid behaving as an ideal gas. It then discusses the Otto cycle which models spark ignition engines and the processes involved. Details of the Otto cycle calculation are provided. The document also discusses the diesel cycle which models compression ignition engines and provides cycle calculations. Other topics covered include mean effective pressure, engine terminology, gas turbine components and cycles like the Brayton cycle.
It is basic information about what is critical thickness and why we should we know this. Then there is critical thickness formula for cylindrical pipe and spherical shell.
Thermal Radiation - III- Radn. energy exchange between gray surfacestmuliya
This file contains slides on THERMAL RADIATION-III: Radiation energy exchange between gray surfaces.
The slides were prepared while teaching Heat Transfer course to the M.Tech. students in Mechanical Engineering Dept. of St. Joseph Engineering College, Vamanjoor, Mangalore, India, during Sept. – Dec. 2010.
Contents: Radiation heat exchange between gray surfaces - electrical network method – two zone enclosures – Problems - three zone enclosures – Problems - radiation shielding – Problems - radiation error in temperature measurement – Problems
Gas Turbine Theory - Principle of Operation and ConstructionSahyog Shishodia
This presentation tells all about basic principle behind Gas Turbine, their working, operation and construction. How they came into existence and where are they used.
This document provides information about air compressors, including reciprocating and rotary compressors. It discusses single stage and two stage reciprocating compressors, detailing their workings using pressure-volume diagrams. It also covers testing methods, classifications, and efficiency parameters for compressors. Rotary compressor types like screw, vane, and lobe compressors are introduced as well.
The document provides an overview of the basic parts of a steam turbine, including turbine casings, rotors, blades, stationary blades and nozzles, shrouds, barring devices, seals, couplings, governors, and lubrication systems. It describes the materials, designs, and purposes of each part. The rotors can be disc-type or drum-type, depending on the turbine design. Blades are made of heat-resistant alloys and fastened via different methods. Seals prevent steam leakage and include shaft seals like carbon rings or labyrinth seals and blade seals such as labyrinth seals. Larger turbines use pressurized lubrication systems to lubricate bearings.
The document summarizes key concepts about reciprocating air compressors:
1) It describes the basic components and working of a single-stage, double-acting reciprocating air compressor using a labeled diagram. The compressor consists of a piston that reciprocates in a cylinder driven by a crankshaft, with inlet and outlet valves.
2) It explains the ideal thermodynamic cycle on p-V and T-S diagrams, involving constant-pressure intake, adiabatic compression, and constant-pressure discharge processes.
3) It defines mechanical efficiency and indicated power for reciprocating compressors, and describes calculations for work of compression and various efficiencies like isothermal efficiency.
This document presents the design of a nine-stage transonic axial compressor. It specifies the initial design parameters, including nine stages, a rotating speed of 9000 rpm, and ambient conditions. Calculations are shown to determine the blade angles, pressure and temperature ratios, mass flow rate, and shaft power for each stage. The results provide the inlet and outlet blade angles, pressure ratio per stage and overall, mass flow rate, and shaft power. The conclusion states that the key design values calculated include the blade angles, pressure ratios, and shaft power.
This document provides an overview of gas turbine engine design, focusing on compressor and turbine components. It discusses:
1) How gas turbine engines work by compressing air, mixing it with fuel, combusting the mixture to produce thrust or shaft power via Newton's third law.
2) The major components of compressors (axial, centrifugal) and turbines (axial, radial), how they operate to compress or expand the working fluid, and examples of each type.
3) Key design challenges like thermal issues, blade stalls, and dynamic surge; and methods to address them like various cooling techniques.
4) The basic process of axial compressor design which involves defining needs, determining rotational speed, estimating
Refrigeration and air conditioning (full note)shone john
Principles of refrigeration: Thermodynamics of refrigeration - Carnot cycle,
reversed carnot cycle, heat pump, and refrigerating machine- coefficient of
performance - unit of refrigeration - refrigeration methods- conventional
refrigeration systems. Air refrigeration system- Bell Coleman cycle - C.O.P.
capacity work and refrigerant flow requirements in Bell - Coleman cycle.
Module 2
Vapour compression system: simple cycle -comparison with Carnot cycle -
theoretical, actual and reactive - COP effect of operating parameters on
COP - wet, dry and superheated compression - under cooling - actual cycle
representation on TS and PH diagrams simple problems. Advanced
vapour compression systems - multistage vapour compression systems -
flash chamber multiple compression and evaporation systems cascading -
simple problems.
Module 3
Vapour absorption systems: simple, cycles - actual cycle - ammonia water
and lithium bromide water systems - COP - electrolux system. Refrigerant
and their properties: Nomenclature - suitability of refrigerants for various
applications - unconventional refrigeration methods- Vortex tube, steamjet, magnetic (cryogenics) refrigeration and thermoelectric refrigeration -
applied refrigeration house hold refrigerators - unit air conditioners andModule 4
Refrigeration system components: condensers - water and air cooled
condensers - evaporative condensers - expansion devises - capillary tubeconstant pressure expansion valve - thermostatic expansion valve - float
valve and solenoid valve - evaporators - natural convection coils - flooded
evaporators - direct expansion coils. Reciprocating compressors: single
stage and multistage compressors - work done optimum pressure ratioeffect of interfolding - volumetric efficiency -effect of clearance -
isothermal and adiabatic efficiency - compressed air motors. Rotodynamic
compressors: Screw and vane type compressors - principle of operation -
hermetic, semihermetic and open type refrigeration compressors.
Module 5
Principles of air conditioning: Psychrometry and psychrometric chart
thermodynamics of human comfort - effective temperature - comfort chart
applied psychrometry - sensible heat factor - psychometric processproblems. Winter air conditioning: heating load calculations humidifiers
and humidistat. Summer air conditioning: cooling load calculations - year
round air conditioning - unitary and central systems - principles of air
distribution - design of air duct systems.
References
1. Refrigeration and air conditioning - Ballaney P. L.
2. Refrigeration and air conditioning - Stocker W. F.
3. Refrigeration and air conditioning - Jordan and Protester
4. Principles of Refrigeration - Roy J. Dossat
Definition and Requirements
Types of Heat Exchangers
The Overall Heat Transfer Coefficient
The Convection Heat Transfer Coefficients—Forced Convection
Heat Exchanger Analysis
Heat Exchanger Design and Performance Analysis
1. The document discusses gas turbine cycles with two shafts, where one turbine drives the compressor and the other provides power output. It describes regeneration using a heat exchanger to improve efficiency by heating the compressed air. Intercooling between compression stages and reheating are also discussed to reduce the work of compression. Examples are provided to calculate efficiency, power output, temperatures and pressures at different points in regenerative cycles with variations like intercooling.
The document summarizes key aspects of steam turbines. It begins by explaining that a steam turbine converts the heat energy of steam into kinetic energy and then rotational energy to generate power. It then describes the basic Rankine cycle used in steam turbine power plants.
The main body explains the principles of operation for impulse and reaction turbines. In an impulse turbine, steam expands within nozzles and does not change pressure as it moves over blades, while in a reaction turbine steam pressure gradually drops as it expands over fixed and moving blades.
Finally, it discusses methods to improve efficiency, such as compounding and reheat, where dividing the expansion process into multiple stages separated by reheaters increases overall efficiency compared to a single stage by
The document summarizes the combustion chamber of a jet engine. It discusses how an air-fuel mixture burns inside the combustion chamber and how proper combustion and stabilization of the flame are essential for optimum engine power. It also describes the various requirements of a combustion chamber, including maintaining stable combustion over a wide range of operating conditions, high combustion efficiency, withstanding high temperatures, and minimizing pressure loss during combustion.
The document discusses combustion chamber design and types for gas turbine engines. It describes the key requirements for combustion chambers including low weight, stable and efficient combustion over operating conditions, and uniform temperature distribution. It classifies combustion chambers as can, can-annular, or annular and describes the characteristics and advantages/disadvantages of each type. Important factors for combustion chamber design are maintaining suitable turbine inlet temperatures, stable combustion over a range of operating conditions, and controlling emissions.
This document discusses the Rankine cycle, which is a thermodynamic cycle derived from the Carnot vapor power cycle. It consists of four processes: 1) Isobaric heat supply in the boiler where water is heated to high pressure steam, 2) Adiabatic expansion of the steam in a turbine to produce work, 3) Isobaric heat rejection in the condenser where the steam is condensed back to water, and 4) Adiabatic pumping of the condensate back to the boiler to complete the cycle. The heat and work transfers are also defined for each process.
Need for cooling of an aircraft. types of air-refrigeration system, DART, Advantages of air refrigeration system, Open and closed cycle air refrigeration,
This document discusses calculations of air-fuel ratios in carburators. It first describes the basic components and airflow in a simple carburator. It then presents equations for determining the theoretical mass airflow rates of both air and fuel through the carburator, taking into account factors like compressibility of air, pressure differences, temperatures and densities. The document concludes that the air-fuel ratio depends on factors like the venturi throat diameter, fuel jet diameter, pressure difference across the venturi and densities of air and fuel. It also provides an example problem solving for the air-fuel ratio of a carburator with given specifications under two conditions, neglecting and accounting for the fuel nozzle tip.
Design of machine elements - V belt, Flat belt, Flexible power transmitting e...Akram Hossain
This document provides the solution to a multi-part design problem involving the design of a belt drive system. It selects appropriate pulley sizes and belt widths using standard design procedures and tables. It calculates key parameters like belt stress, operating tensions, and initial tension. The initial tension is found to be reasonable compared to recommendations. The document also provides a recommendation to potentially redesign the system for greater economy.
The document discusses gas turbine cycles and thermodynamic cycles used in gas turbines. It begins by describing air standard cycles and assumptions made, including the working fluid behaving as an ideal gas. It then discusses the Otto cycle which models spark ignition engines and the processes involved. Details of the Otto cycle calculation are provided. The document also discusses the diesel cycle which models compression ignition engines and provides cycle calculations. Other topics covered include mean effective pressure, engine terminology, gas turbine components and cycles like the Brayton cycle.
It is basic information about what is critical thickness and why we should we know this. Then there is critical thickness formula for cylindrical pipe and spherical shell.
Thermal Radiation - III- Radn. energy exchange between gray surfacestmuliya
This file contains slides on THERMAL RADIATION-III: Radiation energy exchange between gray surfaces.
The slides were prepared while teaching Heat Transfer course to the M.Tech. students in Mechanical Engineering Dept. of St. Joseph Engineering College, Vamanjoor, Mangalore, India, during Sept. – Dec. 2010.
Contents: Radiation heat exchange between gray surfaces - electrical network method – two zone enclosures – Problems - three zone enclosures – Problems - radiation shielding – Problems - radiation error in temperature measurement – Problems
Gas Turbine Theory - Principle of Operation and ConstructionSahyog Shishodia
This presentation tells all about basic principle behind Gas Turbine, their working, operation and construction. How they came into existence and where are they used.
This document provides information about air compressors, including reciprocating and rotary compressors. It discusses single stage and two stage reciprocating compressors, detailing their workings using pressure-volume diagrams. It also covers testing methods, classifications, and efficiency parameters for compressors. Rotary compressor types like screw, vane, and lobe compressors are introduced as well.
The document provides an overview of the basic parts of a steam turbine, including turbine casings, rotors, blades, stationary blades and nozzles, shrouds, barring devices, seals, couplings, governors, and lubrication systems. It describes the materials, designs, and purposes of each part. The rotors can be disc-type or drum-type, depending on the turbine design. Blades are made of heat-resistant alloys and fastened via different methods. Seals prevent steam leakage and include shaft seals like carbon rings or labyrinth seals and blade seals such as labyrinth seals. Larger turbines use pressurized lubrication systems to lubricate bearings.
The document summarizes key concepts about reciprocating air compressors:
1) It describes the basic components and working of a single-stage, double-acting reciprocating air compressor using a labeled diagram. The compressor consists of a piston that reciprocates in a cylinder driven by a crankshaft, with inlet and outlet valves.
2) It explains the ideal thermodynamic cycle on p-V and T-S diagrams, involving constant-pressure intake, adiabatic compression, and constant-pressure discharge processes.
3) It defines mechanical efficiency and indicated power for reciprocating compressors, and describes calculations for work of compression and various efficiencies like isothermal efficiency.
This document presents the design of a nine-stage transonic axial compressor. It specifies the initial design parameters, including nine stages, a rotating speed of 9000 rpm, and ambient conditions. Calculations are shown to determine the blade angles, pressure and temperature ratios, mass flow rate, and shaft power for each stage. The results provide the inlet and outlet blade angles, pressure ratio per stage and overall, mass flow rate, and shaft power. The conclusion states that the key design values calculated include the blade angles, pressure ratios, and shaft power.
This document provides an overview of gas turbine engine design, focusing on compressor and turbine components. It discusses:
1) How gas turbine engines work by compressing air, mixing it with fuel, combusting the mixture to produce thrust or shaft power via Newton's third law.
2) The major components of compressors (axial, centrifugal) and turbines (axial, radial), how they operate to compress or expand the working fluid, and examples of each type.
3) Key design challenges like thermal issues, blade stalls, and dynamic surge; and methods to address them like various cooling techniques.
4) The basic process of axial compressor design which involves defining needs, determining rotational speed, estimating
This document provides information about axial flow compressors including:
- They consist of multiple rows of fixed and moving blades that continuously pressurize gas flowing parallel to the axis of rotation, achieving high efficiency and mass flow.
- Each pair of rotor and stator blades constitutes a pressure stage, with typical single stage pressure increases of 15-60% and multiple stages used to achieve higher overall pressure ratios.
- Stalling and surging refer to unstable flow conditions that reduce compressor performance and must be avoided through proper design and operation.
- They find applications in industries like oil refining and power generation as well as aircraft engines due to their high performance capabilities.
There are two basic types of compressors: reciprocating piston compressors which are used for low flow rates and high compression ratios, and centrifugal compressors which are used for high flow rates and low compression ratios. The design equations for compressors are derived from the mechanical energy balance and total energy balance, assuming adiabatic and isentropic compression. In reality, compression is neither fully adiabatic nor isentropic, so a polytropic model provides a better approximation of the actual compression process.
Axial compressor - variation of rotor and stator angles from root to tip - 4t...CangTo Cheah
The document discusses the theory behind how rotor and stator angles in an axial compressor vary from the root to the tip. It presents equations showing how angles, velocities, and other parameters change based on radial position. The analysis aims to evaluate these variations while maintaining constant specific work input at all radii, which provides a constant stage pressure ratio up to the blade height. The equations derived indicate that for certain rotor and stator velocity distributions, the two design conditions of constant specific work input and arbitrary whirl velocity profiles are compatible.
Axial compressor theory - stage-by-stage approach - 28th January 2010CangTo Cheah
The document discusses the stage-by-stage sizing approach for axial compressors. This approach allows designers to calculate blade angles and estimate pressure rise, temperature rise, and frictional losses at each stage. It introduces concepts like the de Haller number to minimize losses. A case study on the RB211-24G engine axial compressors is presented, showing blade angles and performance across 7 low pressure and 6 high pressure stages.
Aircraft propulsion axial flow compressors off design performanceAnurak Atthasit
The document discusses axial flow compressors and their off-design performance. It covers topics such as compressor maps, surge lines, efficiency islands, best efficiency points, operating lines, surge margins, effects of inlet pressure distortion, Reynolds number, Mach number, and tip clearance on compressor performance. The conclusion summarizes that changes in total temperature, total pressure, Mach number, and density can affect compressor operation and efficiency.
This document provides an introduction to the analysis and design of a compressor shelter. It discusses key items of the compressor shelter including the operating platform, hoisting devices, and enclosure. The objective is to analyze and design the structural components of the compressor shelter considering loads, material properties, and support conditions to protect the compressor equipment from environmental factors. The analysis will involve modeling the shelter in STAAD.Pro, calculating loads, and designing structural elements like purlins, gantry, foundation, and connections. A parametric study will also be conducted to optimize the structural geometry.
1. The document discusses jet propulsion and compressor design, focusing on different types of turbines, compressors, and propulsion systems like propellers, rockets, turbojets, and scramjets.
2. It analyzes the advantages of propellers over rockets for aircraft propulsion in terms of efficiency and fuel requirements.
3. The importance of compressors and turbines in enabling modern high-speed flight is discussed, with examples given of how these technologies allowed the development of planes like the Blackbird that could reach supersonic speeds.
The document provides the engineering problem definition, requirements, and analysis for designing a turbojet engine. It defines the operating conditions, constraints, and performance parameters to analyze. An engineering analysis is then presented using MATLAB code to calculate temperatures, pressures, mass flows, and other parameters across the engine for a range of compressor pressure ratios from 2 to 40. Graphs of key parameters like thrust, temperatures, mass flow, and efficiency are plotted to identify the highest performing compressor pressure ratio design.
Centrifugal and axial compressors are the two main types used in aircraft jet engines. Centrifugal compressors have advantages like being cheap and resistant to foreign object damage, but have limitations like a lower compression ratio. Axial compressors can achieve higher compression ratios but are more complex and prone to stall and surge issues. Both compressor types work by continuously increasing the pressure of air through multiple compressor stages or rows of rotor blades and stator vanes. Anti-surge devices help control airflow and prevent compressor stall and surge.
The document discusses centrifugal compressors. It begins with an introduction to air compressors in general, then describes the two main types: positive-displacement and dynamic-displacement. It focuses on centrifugal compressors, which use a rotating impeller to impart kinetic energy to air and compress it. The key components of a centrifugal compressor are the inlet, impeller, diffuser, and collector. Centrifugal compressors are commonly used in applications like gas turbines, turbochargers, pipelines, and HVAC due to benefits like fewer parts and higher efficiency compared to reciprocating compressors. However, they have a lower maximum compression ratio than reciprocating compressors.
Design optimization of an axial flow compressor for industrial gas turbineeSAT Publishing House
This document summarizes the design optimization process of an axial flow compressor for an industrial gas turbine. It describes the steps taken, which included preliminary design using 1D and 2D simulations to select design parameters, computational fluid dynamics (CFD) analysis to validate the design, off-design performance mapping, blade profiling and 3D blade design, structural and modal analysis of the blades, and final 3D CFD flow analysis. The optimized design showed close agreement with the theoretical design goals of delivering the required mass flow at the target outlet pressure with wide stability margins at low losses.
This document provides an overview of gas turbine design fundamentals and concepts. It discusses the key components of gas turbines, including compressors, burners, and turbines. It covers centrifugal and axial flow designs. The document also presents examples calculations for gas turbine power and efficiency. Overall, the document aims to provide students with an understanding of gas turbine theory, design, practical considerations, and comparisons between different gas turbine types and cycles.
This document discusses the design and testing of a valveless pulsejet engine. It describes the key components of the engine, including the intake pipe, combustion chamber, and tailpipe. Parameters like material choice, fuel type, and nozzle dimensions are analyzed. The engine is constructed and tested. Testing results in improved thrust and fuel efficiency. Applications of pulsejet engines include unmanned aerial vehicles and civil defense. Future developments could include pulse detonation engines.
This presentation had been prepared for the aircraft propulsion class to my undergraduate and graduate students at Kasetsart University and Chulalongkorn University - Bangkok, Thailand.
The document describes a student project to develop a pulsejet-rotor engine. A pulsejet engine uses combustion pulses for propulsion and has simplicity, low cost, and high thrust-to-weight. The students designed a prototype engine with 3 pulsejets arranged circularly to drive cups and create rotational motion. Testing showed the design was feasible but would require fuel control and cooling to optimize performance. While pulsejets are more efficient than other jets, challenges include low average pressure and high temperatures.
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The turboprop engine has a compressor section that pressurizes air, a combustion chamber where fuel is burned, and a reduction gearbox that reduces the high rpm of the turbine to a lower rpm to turn the propeller more efficiently. The fuel nozzle injects fuel into the combustion chamber where an igniter plug ignites the fuel-air mixture to produce thrust to turn the turbine and propeller.
Structures Group - Final presenttion 2012Delwar Hoque
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The document discusses Stirling engines and their operation using biomass as fuel. Some key points:
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This document discusses the ideal efficiencies of various gas turbine cycles including simple, heat exchange, reheat, and reheat with heat exchange cycles. It provides graphs comparing the efficiencies of these cycles at different pressure ratios. A simple cycle has the highest efficiency at higher pressure ratios, while a heat exchange cycle is best for lower pressure ratios. Adding reheat or combining with heat exchange does not increase efficiency compared to a simple cycle beyond certain pressure ratio thresholds. The optimal configuration depends on the operating pressure ratio of the turbine.
Engineering webinar material dealing with simple and basic Brayton Cycle and power cycle components/processes and their T - s diagrams, ideal and real operation and major performance trends when air is considered as the working fluid.
The air-standard cycle is an idealized cycle founded on the following approximations: (1) The working fluid throughout the cycle is only air; (2) the air acts as an ideal gas; (3) combustion processes are replaced by well-defined heat addition processes; and (4) the exhaust process is replaced by a heat rejection ...
The document discusses the performance calculation of a gas turbine. It provides definitions of gas turbine performance, assumptions made in the ideal gas turbine cycle calculations, and equations used. It then lists input parameters such as temperatures, pressures, and flows. The calculations determine values like isentropic temperatures and enthalpies. Performance metrics of the compressor, combustion chamber, and turbine are calculated, such as works, efficiencies, heat rates, and fuel consumption. The summary provides the overall performance results including shaft work, thermal efficiency, fuel consumption rate, and plant efficiency.
This webinar introduces engineering concepts related to energy conversion cycles and compressible flow. It covers the Carnot, Brayton, Otto and Diesel cycles, discussing their schematics, T-s and p-V diagrams, assumptions, and performance trends. It also examines the components of these cycles including compression, combustion and expansion processes. Finally, it reviews compressible flow concepts such as nozzles, diffusers and thrust, as well as the assumptions and governing equations used in the analysis. The webinar aims to familiarize engineering students and professionals with basic energy conversion engineering and performance trends when air is considered the working fluid.
Gas Power Cycles in Chemical Engineering Thermodynamics.pptHafizMudaserAhmad
This document describes several gas power cycles including ideal cycles like the Otto cycle, Diesel cycle, and Brayton cycle as well as actual engine cycles. It provides details on the assumptions and processes of each ideal cycle. The Otto cycle involves four internally reversible processes including isentropic compression and expansion with constant-volume heat addition and rejection. The Diesel cycle similarly involves isentropic compression and expansion but with constant-pressure rather than constant-volume heat addition. The Brayton cycle models gas turbine engines with isentropic compression and expansion and constant-pressure heat transfer. Regeneration and intercooling are discussed as ways to improve upon actual engine cycles.
This document describes several gas power cycles including ideal cycles like the Otto cycle, Diesel cycle, and Brayton cycle as well as actual engine cycles. It provides details on the assumptions and processes of each ideal cycle. The Otto cycle involves four internally reversible processes: isentropic compression, constant-volume heat addition, isentropic expansion, and constant-volume heat rejection. The Diesel cycle also involves four internally reversible processes but with compression ignition. The Brayton cycle is typically used in gas turbines and involves isentropic compression, constant-pressure heat addition, isentropic expansion, and constant-pressure heat rejection. Regeneration and intercooling can improve the efficiency of actual cycles.
The document discusses closed cycle gas power plants. It begins with an introduction that defines closed cycle systems as those where a working gas like air is compressed, heated, expanded through a turbine to produce power, cooled, and recycled through the system. It then discusses the main components of closed cycle plants including compressors, combustion chambers, turbines, generators, and intercoolers. The working principle involves isentropic compression, constant pressure heating, isentropic expansion in the turbine, and constant pressure cooling. Key improvements discussed include higher operating temperatures through improved materials and cooling, and cycle modifications like regeneration to increase efficiency. Advantages are high efficiency while disadvantages include greater complexity versus open cycle plants.
This document provides an overview and goals for reviewing the course AE430 Aircraft Propulsion Systems. It outlines the following key points:
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2) Component analysis will include inlets, combustors, compressors, and turbines using concepts like oblique shock analysis, velocity triangles, and pressure/temperature changes.
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1. The document describes the Brayton cycle, which is the ideal cycle for gas turbine engines. It involves four processes: isentropic compression, constant pressure heat addition, isentropic expansion, and constant pressure heat rejection.
2. Various techniques can improve the efficiency of the Brayton cycle, including regeneration, intercooling between compression stages, and reheating between expansion stages. Regeneration involves heating the compressed air with the exhaust gases in a heat exchanger.
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Improved efficiency of gas turbine by Razin Sazzad MollaRazin Sazzad Molla
This document discusses ways to improve the efficiency of gas turbine engines through various design modifications and upgrades. It describes how increasing turbine inlet temperatures, improving compressor and turbine components, adding modifications like intercooling and regeneration, and utilizing advanced cooling techniques can boost efficiency. Other methods covered include inlet air cooling systems, compressor and turbine coatings, supercharging, and comprehensive component replacements. The goal of ongoing research is to enhance power output while reducing emissions and fuel consumption.
This document discusses the effects of friction on the Joule cycle used in gas turbines. It states that friction reduces the turbine's power output and increases the compressor's power input, resulting in lower net power and thermal efficiency. Diagrams are provided showing how friction lowers the temperature change in both the turbine and compressor processes compared to the ideal case. The document then provides an example calculation for a gas turbine cycle accounting for the isentropic efficiencies of the turbine and compressor due to friction.
The document provides an overview and goals for analyzing different types of gas turbine engines including turbojet, turbofan, and ramjet engines. It outlines the planned analysis of individual engine components including inlets, combustors, compressors, turbines, and control volume analysis. The analysis will use thermodynamic cycles and definitions of efficiency to evaluate performance parameters like propulsion efficiency, thermal efficiency, and thrust specific fuel consumption. Both ideal and non-ideal analyses are discussed for ramjet and turbojet engines.
The document discusses turbochargers and superchargers. It begins by explaining how engine power depends on air intake and efficiency. It then describes three methods to increase air consumption: increasing displacement, running at higher speeds, and increasing charge density. Superchargers and turbochargers both increase charge density by compressing air intake. A supercharger is mechanically driven while a turbocharger uses exhaust gas energy. The document outlines the components, working principles, advantages, disadvantages, and selection process for turbochargers. It also presents experimental results showing increased torque, power, and reduced exhaust temperatures from a turbocharged tractor engine compared to naturally aspirated.
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Thermodynamics of axial compressor and turbine - 3rd December 2009
1. Gas Turbine Axial
Compressors andCompressors and
Turbines
Thermodynamics calculationsThermodynamics calculations
3rd December 2009
Prepared by: Cheah CangTo
Supervised by: James Richard Bryan
2. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Objectives of this discussion:
a) Overview of Brayton cycle.
b) Is to provide the insight of prediction on thermodynamics performances of
gas turbine axial compressor and turbine.
c) Note when considering the fundamentals of axial compressor and turbine
design, it should be emphasized that successful compressor / turbine design
is very much an art, and all the major engine manufacturers have developed
a body of knowledge which is kept proprietary for competitive reasons.
2Thermodynamics of axial compressor
a body of knowledge which is kept proprietary for competitive reasons.
3. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Overview of Brayton cycle
The Brayton cycle was first proposed by George Brayton for use in the
reciprocating oil-burning engine that he developed around 1870. Today, it isreciprocating oil-burning engine that he developed around 1870. Today, it is
used for gas turbines only where both the compression and expansion
processes take place in rotating machinery.
Picture taken from Wikipedia
1 to 2: Isentropic air compression1 to 2: Isentropic air compression
2 to 3: Isobaric (constant pressure) heat addition
3 to 4: Isentropic expansion of heated air
3Thermodynamics of axial compressor
4 to 1: Isobaric heat rejection (for closed-cycle)
4. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
With input parameters:
a) air mass flow ratea) air mass flow rate
b) compressor compression ratio (note turbine expansion ratio is
proportional per Brayton’s P-v diagram discussed earlier)
c) inlet temperaturec) inlet temperature
d) polytropic efficiency
Basically, there are two parameters needed to be evaluated:
a) shaft power requires to perform compression work
b) temperature rises at compressor outlet
4Thermodynamics of axial compressor
5. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Formula for gas power
Power (kJ/s = kW) = mass flow rate (kg/s) x specific heat capacity at constant pressurePower (kJ/s = kW) = mass flow rate (kg/s) x specific heat capacity at constant pressure
(kJ/kg.K) x delta temperature (K)
Known / given: mass flow rate
To find:To find:
a) specific heat capacity at constant pressure, Cp
b) delta temperature = T_out – T_in (note: Inlet temperature, T_in is given)b) delta temperature = T_out – T_in (note: Inlet temperature, T_in is given)
5Thermodynamics of axial compressor
6. Specific heat capacity at constant pressure, Cp is a function of temperature.
TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Specific heat capacity at constant pressure, Cp is a function of temperature.
What should the temperature be? Inlet temperature or outlet temperature?
The answer is mean temperature, i.e. T_mean = (T_in + T_out)/2 should be used in order
to evaluate Cp.
But, how do we calculate T_mean since T_out is an unknown parameter.But, how do we calculate T_mean since T_out is an unknown parameter.
This problem can be solved by iteration method, i.e. take T_mean = T_in (i.e. without
T_out) for the first pass of iteration loop until values of T_out converge.
A0 0.992313
A1 0.236688
A2 -1.852148
A3 6.083152
A4 -8.893933
A5 7.097112
A6 -3.234725
A7 0.794571
A8 -0.081873A8 -0.081873
8765432
1000
8
1000
7
1000
6
1000
5
1000
4
1000
3
1000
2
1000
10
×+
×+
×+
×+
×+
×+
×+×+= meanmeanmeanmeanmeanmeanmeanmean
p
T
A
T
A
T
A
T
A
T
A
T
A
T
A
T
AAC
6Thermodynamics of axial compressor
7. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Outlet temperature, T_out is a function of:
a) pressure ratioa) pressure ratio
b) gama = Specific gas constant / (Specific gas constant – specific heat capacity at
constant pressure)
c) inlet temperaturec) inlet temperature
d) isentropic efficiency of compressor it is defined on following page
inTratiopressure
×
−
−
γ
γ
1_
1
in
isentropic
in
out TT +
=
η
7Thermodynamics of axial compressor
b) gama = Specific heat capacity at constant pressure / (Specific heat capacity at constant
pressure - Specific gas constant)
8. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Isentropic efficiency of compressor is a function of:
a) pressure ratioa) pressure ratio
b) gama
c) polytropic efficiency
1_
1
−
−
ratiopressure γ
γ
1_
1
−
= −
ratiopressure
isentropic γ
γ
η
1_ −
× polytropic
ratiopressure
ηγ
8Thermodynamics of axial compressor
9. 1−γ
TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
1_
1_
1
1
−
−
=
×
−
−
polytropic
ratiopressure
ratiopressure
isentropic
ηγ
γ
γ
γ
η
1_ −ratiopressure
Isentropic efficiency of compressor falls as pressure ratio is
increased for the same polytropic efficiency.
9Thermodynamics of axial compressor
10. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
In the previous slide, we learned that isentropic efficiency of compressor falls as
compression ratio increases.
But why GT manufacturers are building high pressure ratio machines (e.gBut why GT manufacturers are building high pressure ratio machines (e.g
LMS100, compression ratio of 40:1)?
Reasons are:Reasons are:
a) Isentropic efficiency of turbine increases as expansion ratio increases.
b) Higher OVERALL (combination of compressors, combustors, diffusers, turbineb) Higher OVERALL (combination of compressors, combustors, diffusers, turbine
expanders, etc) efficiency. Overall efficiency means net shaft output power
divided by fuel input power. Compression work is taking energy from the fuel, in
contrast turbine is extracting work from it. Turbine work is defined by:contrast turbine is extracting work from it. Turbine work is defined by:
∆××=
•
TCpmPower turbineturbine
−××=∆ −
γ
γ 1_
_
1
1
ratioExpansion
EffTT turbineisentropicinturbine
10Thermodynamics of axial compressor
_ ratioExpansion
11. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
In order to maintain maximum temperature drop across turbine, it is necessary to
have higher expansion ratio, this means the pressure shall be kept high at
turbine inlet and low at turbine outlet. This leads to the reason why high powerturbine inlet and low at turbine outlet. This leads to the reason why high power
rating GT requires high compression ratio. Although it is true that a higher T_in
(combustion outlet temperature) will improve efficiency (refer Brayton cycle), for
the purposes of this discussion T_in is assumed constant since all turbinethe purposes of this discussion T_in is assumed constant since all turbine
manufacturers have similar combustor outlet temperatures to maximize
efficiency.
c) Mismatch (in term of air density) between compressor and turbine affecting
overall GT efficiency occurs on high compression ratio machine at high ambientoverall GT efficiency occurs on high compression ratio machine at high ambient
temperature. This effect can be clearly seen when comparing temperature de-
rate curves between low pressure ratio industrial gas turbines versus high
pressure ratio aero-derivative gas turbines. However, the topic is out of scope ofpressure ratio aero-derivative gas turbines. However, the topic is out of scope of
this discussion.
11Thermodynamics of axial compressor
12.
TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
−××=∆ −
γ
γ 1_
_
1
1
ratioExpansion
EffTT turbineisentropicinturbine
Delta T across turbine vs expansion ratio
800
γ
_ ratioExpansion
700
750
800
DeltaTemperature(K)
600
650
DeltaTemperature(K)
500
550
DeltaTemperature(K)
400
450
0 5 10 15 20 25 30 35 40
Expansion ratio
12Thermodynamics of axial compressor
Expansion ratio
13. •
TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
turbineturbine TCpmPower ∆××=
•
Turbine power output vs expansion ratio
90000
95000
80000
85000
Turbineshaftpower(kW)
70000
75000
Turbineshaftpower(kW)
55000
60000
65000
Turbineshaftpower(kW)
50000
55000
0 5 10 15 20 25 30 35 40
Expansion ratio
13Thermodynamics of axial compressor
14. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
2.00
Specific work output vs pressure ratio T3/T1 = 2
T3/T1 = 3
T3/T1 = 4
T3/T1 = 5
1.50
T_in)]
T3/T1 = 5
1.00
Specificworkoutput[W/(Cp*T_in
0.50
Specificworkoutput[W/(
0.00
0 5 10 15 20 25 30
-0.50
Pressure ratio
14Thermodynamics of axial compressor
15. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
2.00
Specific work output vs pressure ratio T3/T1 = 2
T3/T1 = 3
T3/T1 = 4
1.50
T_in)]
T3/T1 = 5
PR=17
1.00
Specificworkoutput[W/(Cp*T_in
PR=17
Optimum pressure ratio for a
0.50
Specificworkoutput[W/(
PR=11
Optimum pressure ratio for a
given temperature ratio, T3/T1.
0.00
0 5 10 15 20 25 30
Specificworkoutput[W/(
PR=7
PR=3
-0.50
Pressure ratio
15Thermodynamics of axial compressor
Pressure ratio
16. OVERALL (combination of compressors, combustors, diffusers, turbine expanders, etc) efficiency
TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
OVERALL (combination of compressors, combustors, diffusers, turbine expanders, etc) efficiency
increases as compression ratio increases.
Overall GT efficiency versus compression ratio
OverallgasturbineefficiencyOverallgasturbineefficiencyOverallgasturbineefficiency
( )rationcompressiooverall _ln09979.007641.0 ×+=η ( )rationcompressiooverall _ln09979.007641.0 ×+=η
Note: Overall GT efficiency is derived from machine manufacturers’
published heat rate..
Compression ratio
Gas turbine heat rate data courtesy of James Bryan
[GSGnet.net (2009)]
16Thermodynamics of axial compressor
Compression ratio
17. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
GT thermal efficiency versus pressure ratio:
comparison between Brayton and actual cycle
0.6
0.7
1
0.5
0.6
Brayton
Actual
γ
γ
η 1
1
2
1
1 −
−=
P
P
Brayton
0.4
0.3
×+= 2
ln09979.007641.0
P
P
actualη
0.1
0.2
1P
0.0
0.1
17Thermodynamics of axial compressor
0 5 10 15 20 25 30 35 40
18. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
GT thermal efficiency versus pressure ratio:
comparison between Brayton and actual cycle
0.6
0.7
0.5
0.6
Brayton
Actual
Reduction of thermal efficiency due
to irreversible losses.
0.4
to irreversible losses.
0.3
0.1
0.2
0.0
0.1
18Thermodynamics of axial compressor
0 5 10 15 20 25 30 35 40
19. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
But, hang on a second…previous slide tells us overall GT efficiency goes up as
compression ratio increases (or temperature drop across turbine increases ascompression ratio increases (or temperature drop across turbine increases as
expansion ratio increases), then why GT manufacturer don’t produce high
efficiency machine, let say more than 50% at the expense of high compression
ratio?ratio?
The reason behind this, at least what I have in mind is explained on the following
pages.
19Thermodynamics of axial compressor
20. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Let us revisit “Delta temperature versus expansion ratio” curve presented earlier.
Delta T across turbine vs expansion ratioDelta T across turbine vs expansion ratio
750
800
650
700
DeltaTemperature(K)
3
25
Temperature drop is more sensitive on expansion
550
600
DeltaTemperature(K)
65
Temperature drop is more sensitive on expansion
ratio of low pressure range compared to high
pressure range. It means rate of change of
efficiency is decreasing with increasing expansion
ratio.
450
500
3
From this point onwards, please be absolute clear
that (don’t confuse):
a) Overall GT efficiency increases as expansion
ratio increases.
b) Rate of change of overall GT efficiency
decreases as expansion ratio increases.
400
0 5 10 15 20 25 30 35 40
Expansion ratio
decreases as expansion ratio increases.
20Thermodynamics of axial compressor
21. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
In order to quantify sensitivity of efficiency as a function of expansion ratio, the following
expression is derived: by differentiating the curve function described previously to obtain
slope gradient.
Rate of change of efficiency = delta temperature turbine / delta expansion ratioRate of change of efficiency = delta temperature turbine / delta expansion ratio
−××=∆
1
−××=∆ −
γ
γ 1_
_
1
1
ratioExpansion
EffTT turbineisentropicinturbine
These are nearly constant
( )24812.0
_1 −
−=∆ ratioExpansionT
Gama = 1.33 (for turbine)
24812.1
_24812.0 −
×= ratioExpansion
dT
( )24812.0
_1 −
−=∆ ratioExpansionT
( )
24812.1
_24812.0
_
−
×= ratioExpansion
ratioExpansiond
dT
It is proposed that this new function is used as the basis for gas turbine
performance prediction and comparison within a database environment.
21Thermodynamics of axial compressor
performance prediction and comparison within a database environment.
22. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Rate of change of overall GT efficiency as a function of expansion ratio is now defined:
( )
24812.1
_24812.0
_
−
×= ratioExpansion
ratioExpansiond
dT
( )ratioExpansiond
dT
_ ( )_ ratioExpansiond
0.12
This curve (dT/d[expansion ratio]) enables us to visualize how sensitive is
overall GT efficiency as a function of expansion ratio.
( )ratioExpansiond _
0.08
0.1
overall GT efficiency as a function of expansion ratio.
LM 6000
Compression ratio = 28.1
LMS 100
Compression ratio = 40
0.06
0.08
0.04
0
0.02
0 10 20 30 40 50 60
22Thermodynamics of axial compressor
0 10 20 30 40 50 60
Expansion
ratio
23. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Overall GT efficiency merely
increased by 3.43%increased by 3.43%
OverallGTefficiencyOverallGTefficiencyOverallGTefficiency
23Thermodynamics of axial compressor
Compression ratio
24. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
It’s time to put all theories discussed in the previous section into practical work.
Attempt the following example:
Calculate the isentropic efficiency, outlet temperature and power input for a
compressor (of gas turbine) of 20:1 pressure ratio, polytropic efficiency of
91.07%, with a mass flow of 100 kg/s and an inlet temperature of 35 deg. C.
Also insert a parametric table to investigate the effects (on the outlet
temperature and power input) of changing inlet temperature to 30 and 38 deg. C
respectively.respectively.
24Thermodynamics of axial compressor
25. Input parameters
TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Input parameters
a) Compression ratio 20:1
b) Polytropic efficiency of 91.07%
c) Mass flow of 100 kg/sc) Mass flow of 100 kg/s
d) Inlet temperature of 35 deg. C.
But, something is missing...inlet pressure?
Then make assumption, machine is located at mean sea level, i.e. atmospheric
pressure = 101325 pascal
e) Inlet pressure = 101325 pascale) Inlet pressure = 101325 pascal
Parameters pass 1 pass 2 pass 3 pass 4 pass 5 pass 6 pass 7 pass 8 pass 9 Unit
Cp 1004.33 1039.11 1036.61 1036.78 1036.77 1036.77 1036.77 1036.77 1036.77 J/(kg.K)
gama 1.4002 1.3817 1.3830 1.3829 1.3829 1.3829 1.3829 1.3829 1.3829 -
T_out 788.16 764.59 766.21 766.10 766.10 766.10 766.10 766.10 766.10 K
Outlet temperature is converging from 4th
T_out 788.16 764.59 766.21 766.10 766.10 766.10 766.10 766.10 766.10 K
T_mean 308.15 548.16 536.37 537.18 537.12 537.13 537.13 537.13 537.13 K
Isentropic efficiency 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 -
Outlet temperature is converging from 4th
iteration onwards.
25Thermodynamics of axial compressor
26. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Parameters pass 1 pass 2 pass 3 pass 4 pass 5 pass 6 pass 7 pass 8 pass 9 Unit
Cp 1004.33 1039.11 1036.61 1036.78 1036.77 1036.77 1036.77 1036.77 1036.77 J/(kg.K)
gama 1.4002 1.3817 1.3830 1.3829 1.3829 1.3829 1.3829 1.3829 1.3829 -gama 1.4002 1.3817 1.3830 1.3829 1.3829 1.3829 1.3829 1.3829 1.3829 -
T_out 788.16 764.59 766.21 766.10 766.10 766.10 766.10 766.10 766.10 K
T_mean 308.15 548.16 536.37 537.18 537.12 537.13 537.13 537.13 537.13 K
Isentropic efficiency 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 0.8694 -
Outlet temperature, T_out = 766.10 K or 492.95 deg. C
Shaft power = 100 (kg/s) x 1036.77 (J/kg.K) x [766.10 - 308.15] (K)
= 100 x 1036.77 x 457.95= 100 x 1036.77 x 457.95
= 47478882.15 J/s
= 47479 kW
26Thermodynamics of axial compressor
27. TURBO GROUP – Thermodynamics of Axial Compressor and Turbine
Parametric table
Effects on shaft power and outlet temperature as inlet temperature
changes.
T_in (C) Power (kW) T_out (deg.C) Isentropic efficiency
30 46749 481.65 0.8693
35 47479 492.95 0.8694
changes.
35 47479 492.95 0.8694
38 47917 499.71 0.8694
Shaft power vs inlet temperature Outlet temperature vs inlet temperature
47600
47800
48000
500.0
Outlettemperature(deg.C)
47000
47200
47400
Shaftpower(kW)
490.0
Outlettemperature(deg.C)
46600
46800
30 31 32 33 34 35 36 37 38 39
Inlet temperature (deg. C)
480.0
30 31 32 33 34 35 36 37 38 39
Inlet temperature (deg. C)
Outlettemperature(deg.C)
27Thermodynamics of axial compressor
Inlet temperature (deg. C) Inlet temperature (deg. C)