Gas turbine engines derive their power from burning fuel in a combustion chamber and using the fast flowing combustion gases to drive a turbine in much the same way as the high pressure steam drives a steam turbine. A simple gas turbine is comprised of three main sections a compressor, a combustor, and a power turbine. The gas-turbine operates on the principle of the Brayton cycle, where compressed air is mixed with fuel, and burned under constant pressure conditions. The resulting hot gas is allowed to expand through a turbine to perform work.

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Chapter 7

Gas Turbine Working Principals

Gas turbine engines derive their power from burning fuel in a combustion chamber

and using the fast-flowing combustion gases to drive a turbine in much the same

way as the high-pressure steam drives a steam turbine. A simple gas turbine is

comprised of three main sections: a compressor, a combustor, and a power turbine.

The gas turbine operates on the principle of the Brayton cycle, where compressed

air is mixed with fuel and burned under constant pressure conditions. The resulting

hot gas is allowed to expand through a turbine to perform work.

7.1 Introduction

As the principle of the gas turbine, a working gas (air) is compressed by a

compressor and heated by combustion energy of the fuel at the first. The working

gas becomes the high temperature and high pressure. The engine converts the

energy of working gas into the rotating energy of the blades, making use of the

interaction between the gas and the blades.

As shown in the below figure, there are two types of gas turbine. One is the open

cycle type (internal type) and another is the closed cycle type (external type). Basic

components of both types are the air compressor, a combustor, and the turbine.

The gas turbine can handle a larger gas flow than that of the reciprocating

internal combustion engines, because it utilizes a continued combustion. Then the

gas turbine is suitable as the high power engine. The gas turbine for airplanes

(called a jet engine) makes use of this advantage.

As we said at the beginning of this chapter, the gas turbine operates on the

principle of the Brayton cycle and one variation of this basic cycle is the addition of

a regenerator. A gas turbine with a regenerator (heat exchanger) recaptures some of

the energy in the exhaust gas, preheating the air entering the combustor. This cycle

is typically used on low-pressure ratio turbines, and the resulting hot gas is allowed

to expand through a turbine to perform work. In a 33% efficient gas turbine, almost

©Springer International Publishing AG 2018

B. Zohuri, P. McDaniel, Combined Cycle Driven Efficiency for Next Generation

Nuclear Power Plants,https://doi.org/10.1007/978-3-319-70551-4_7

149

2/3 of this work is spent compressing the air; the rest is available for other work

such as mechanical drive or electrical generation. Figure 7.1 is schematic of such

principle.

Gas turbines with high-pressure ratios can use an intercooler to cool the air

between stages of compression, allowing you to burn more fuel and generate more

power. Remember, the limiting factor on fuel input is the temperature of the hot gas

created, because of the metallurgy of the first stage nozzle and turbine blades. With

the advances in materials technology, this physical limit is always climbing.

Figures. 7.2 and 7.3 are illustrations of a gas turbine, using an intercooling (heat

exchanger), while Fig. 7.4 is presenting a gas turbine with reheater.

The gas turbine can handle a larger gas flow than that of the reciprocating

internal combustion engines, because it utilizes a continued combustion. Then the

gas turbine is suitable as the high power engine. The gas turbine for airplanes

(called a jet engine) makes use of this advantage.

Generally speaking gas turbine is divided into two categories as follows:

1. Open cycle gas turbine

2. Closed cycle gas turbine

Both of these two cycles are presented in Fig. 7.5.

In case of jet engine power plant, as we said, they drive their power from burning

fuel in a combustion chamber and using the fast-flowing combustion gases to drive

a turbine in much the same way as the high-pressure steam drives a steam turbine.

See Fig. 7.6.

GAS-TURBINE WITH REGENERATION

FUEL

PREHEATED

AIR

HOT

GAS

EHAUST

GAS

INLET AIR

COMPRESSED

AIR

COMBUSTOR

POWER TURBINE

COMPRESSOR

Fig. 7.1 Schematic of solar centaur/3500 horsepower class (Courtesy of general electric)

150 7 Gas Turbine Working Principals

INLET AIR

FUEL

COOLANT

HOT

GAS EHAUST

GAS

INTERCOOLER

LOW PRESSURE

COMPRESSOR

HIGH PRESSURE

COMPRESSOR

POWER TURBINE

COMBUSTOR

GAS-TURBINE WITH INTERCOOLING

Fig. 7.2 Illustration of a simple gas turbine with intercooling and combustor (Courtesy of General

Electric)

Fig. 7.3 Thermodynamic model of multi-stage gas turbine using both intercooler and combustor

(Courtesy of general electric)

7.1 Introduction 151

One major difference however is that the gas turbine has a second turbine acting

as an air compressor mounted on the same shaft. The air turbine (compressor) draws

in air, compresses it, and feeds it at high pressure into the combustion chamber

increasing the intensity of the burning flame.

INLET AIR

FUEL MORE FUEL

HOT

GAS

EHAUST

GAS

TURBINE TWO

TURBINE ONE

COMPRESSOR

COMBUSTOR

GAS-TURBINE WITH REHEATER

REHEATER

COMPRESSED

AIR

Fig. 7.4 Schematic of gas turbine with reheater (Courtesy of general electric)

Fuel

Combustor

Turbine

Load

Exhaust

Shaft

Air

Open Cycle Gas Turbine Closed Cycle Gas Turbine

Load

Turbine

Heater

Shaft

Cooler

Fig. 7.5 Configuration of open and close cycle gas turbine (Courtesy of national maritime

research institute)

COMBUSTION CHAMBER

COMPRESSOR TURBINE

JET PIPE AND

PROPELLING NOZZLE

FUEL BURNER

AIR INTAKE

Fig. 7.6 A gas turbine

power plant (Courtesy of

boeing company)

152 7 Gas Turbine Working Principals

It is a positive feedback mechanism. As the gas turbine speeds up, it also causes

the compressor to speed up forcing more air through the combustion chamber

which in turn increases the burn rate of the fuel sending more high-pressure hot

gases into the gas turbine increasing its speed even more. Uncontrolled runaway is

prevented by controls on the fuel supply line which limit the amount of fuel fed to

the turbine thus limiting its speed.

The thermodynamic process used by the gas turbine is known as the Brayton

cycle. Analogous to the Carnot cycle in which the efficiency is maximized by

increasing the temperature difference of the working fluid between the input and

output of the machine, the Brayton cycle efficiency is maximized by increasing the

pressure difference across the turbine. The gas turbine is comprised of three main

components: a compressor, a combustor, and a turbine. The working fluid, air, is

compressed in the compressor (adiabatic compression—no heat gain or loss) and

then mixed with fuel and burned by the combustor under relatively constant

pressure conditions in the combustion chamber (constant pressure heat addition).

The resulting hot gas expands through the turbine to perform work (adiabatic

expansion). Much of the power produced in the turbine is used to run the compres-

sor, and the rest is available to run auxiliary equipment and do useful work. The

system is an open system because the air is not reused so that the fourth step in the

cycle, cooling the working fluid, is omitted.

Gas turbines have a very high power to weight ratio and are lighter and smaller

than internal combustion engines of the same power. Though they are mechanically

simpler than reciprocating engines, their characteristics of high-speed and high-

temperature operation require high-precision components and exotic materials

making them more expensive to manufacture. See Fig.7.7.

Fig. 7.7 Gas turbine aero engine (Courtesy of general electric jet engine division)

7.1 Introduction 153

One big advantage of gas turbines is their fuel flexibility. They can be adapted to

use almost any flammable gas or light distillate petroleum products such as gasoline

(petrol), diesel, and kerosene (paraffin) which happen to be available locally,

though natural gas is the most commonly used fuel. Crude and other heavy oils

can also be used to fuel gas turbines if they are first heated to reduce their viscosity

to a level suitable for burning in the turbine combustion chambers.

Gas turbines can be used for large-scale power generation. Examples are appli-

cations delivering 600 MW or more from a 400 MW gas turbine coupled to a

200 MW steam turbine in a cogenerating installation. Such installations are not

normally used for baseload electricity generation, but for bringing power to remote

sites such as oil and gas fields. They do however find use in the major electricity

grids in peak shaving applications to provide emergency peak power.

Low-power gas turbine generating sets with capacities up to 5 MW can be

accommodated in transportation containers to provide mobile emergency electric-

ity supplies which can be delivered by truck to the point of need.

7.2 Combined Cycle Power Conversion for New

Generation Reactor Systems

A number of technologies are being investigated for the Next Generation Nuclear

Plant that will produce heated fluids at significantly higher temperatures than

current-generation power plants. The higher temperatures offer the opportunity to

significantly improve the thermodynamic efficiency of the energy conversion cycle.

One of the concepts currently under study is the molten salt reactor. The coolant

from the molten salt reactor may be available at temperatures as high as

800–1000 C. At these temperatures, an open Brayton cycle combined with a

Rankine bottoming cycle appears to have some strong advantages. Thermodynamic

efficiencies approaching 50% appear possible. Requirements for circulating cooling

water will be significantly reduced. However, to realistically estimate the efficien-

cies achievable, it is essential to have good models for the heat exchangers involved

as well as the appropriate turbomachinery. This study has concentrated on modeling

all power conversion equipment from the fluid exiting the reactor to the energy

releases to the environment.

Combined cycle power plants are currently commercially available. General

Electric STAG™ (steam turbine and generator) systems have demonstrated high

thermal efficiency, high reliability/availability, and economic power generation for

application in baseload cyclic duty utility service.

Heat recovery-type steam and gas turbine combined cycle systems are the

economic choice for gas or oil-fired power generation. Integration into nuclear

power plants of the next generation is currently being studied and suggested by a

team of universities including the University of New Mexico, Nuclear Engineering

Department, collaborating with this author, independent of others.

154 7 Gas Turbine Working Principals

Incorporation with environmentally clean gasification system is extending their

economic application to low-cost solid fuel utilization. The features contributing to

their outstanding generation economics are:

High thermal efficiency High reliability

Low installed cost High availability

Fuel flexibility—wide range of gas and liquid

fuels

Short installation time

Low operation and maintenance cost High efficiency in small capacity

increments

Operating flexibility—base, midrange, daily start

In electricity generating applications, the turbine is used to drive a synchronous

generator which provides the electrical power output but because the turbine

normally operates at very high rotational speeds of 12,000 r.p.m. or more, it must

be connected to the generator through a high ratio reduction gear since the gener-

ators run at speeds of 1000 r.p.m. or 1200 r.p.m. depending on the alternating

current (AC) frequency of the electricity grid. Gas turbine power generators are

used in two basic configurations.

1. Simple Systems: This system consists of the gas turbine driving an electrical

power generator. The following Fig. 7.8 depicts such a configuration.

2. Combined Cycle Systems: These systems are designed for maximum efficiency

in which the hot exhaust gases from the gas turbine are used to raise steam to

power a steam turbine with both turbines being connected to electricity gener-

ators (Fig. 7.9).

In both cases as part of turbine performance and as turbine power output, we

need to minimize the size and weight of the turbine for a given output power, and

the output per pound of airflow should be maximized. This is obtained by maxi-

mizing the air flow through the turbine which in turn depends on maximizing the

compressor pressure ratio. The main factor governing this is the pressure ratio

across the compressor which can be as high as 40:1 in modern gas turbines. In

simple cycle applications, pressure ratio increases translate into efficiency gains at a

Fig. 7.8 Simple systems

7.2 Combined Cycle Power Conversion for New Generation Reactor Systems 155

given firing temperature, but there is a limit since increasing the pressure ratio

means that more energy will be consumed by the compressor.

Some commercially available and installed combined cycles are presented

below. Several of them that were looked at for purpose of benchmarking the code

developed in this study are boxed. The particular one that was used to validate the

combined cycle (CC, this code was developed by Zohuri and McDaniel at Univer-

sity of New Mexico, Nuclear Engineering Department; for interested party, contact

this author. The code for time being is handling the steady-state cases, and it is in

process of development to transient analysis mode) code [1 ] is identified as S107FA

of General Electric.

Note that the rest of materials presented in this chapter and the following

chapters are results of this author research work at University of New Mexico,

Department of Nuclear Engineering, in collaboration with Professor Patrick

McDaniel (Table 7.1).

7.3 System Efficiency and Turbine Cycles

Thermal efficiency is important because it directly affects the fuel consumption and

operating costs.

•Simple Cycle Turbines

A gas turbine consumes considerable amounts of power just to drive its

compressor. As with all cyclic heat engines, a higher maximum working tem-

perature means greater efficiency (Carnot' s Law), but in a turbine it also means

that more energy is lost as waste heat through the hot exhaust gases whose

temperatures are typically well over 500 C. Consequently, simple cycle turbine

efficiencies are quite low. For a heavy plant, design efficiencies range between

30% and 40%. (The efficiencies of aero engines are in the range 38–42% while

low-power micro-turbines (< 100 kW) achieve only 18–22%.) Although

Fig. 7.9 Combine cycle systems

156 7 Gas Turbine Working Principals

increasing the firing temperature increases the output power at a given pressure

ratio, there is also a sacrifice of efficiency due to the increase in losses due to the

cooling air required to maintain the turbine components at reasonable working

temperatures.

•Combined Cycle Turbines

It is however possible to recover energy from the waste heat of simple cycle

systems by using the exhaust gases in a combined cycle system to heat steam to

drive a steam turbine electricity generating set. In such cases the exhaust

temperature may be reduced to as low as 140 C enabling efficiencies of up to

60% to be achieved in combined cycle systems. In combined cycle applications,

pressure ratio increases have a less pronounced effect on the efficiency since

most of the improvement comes from increases in the Carnot thermal efficiency

resulting from increases in the firing temperature.

Thus simple cycle efficiency is achieved with high-pressure ratios. Combined

cycle efficiency is obtained with more modest pressure ratios and greater firing

temperatures.

Table 7.1 Third generation combined cycle experience

7.3 System Efficiency and Turbine Cycles 157

7.4 Modeling the Brayton Cycle

Any external combustion or heat engine system is always at a disadvantage to an

internal combustion system. The internal combustion systems used in current jet

engine and gas turbine power systems can operate at very high temperatures in the

fluid and cool the structures containing the fluid to achieve high thermodynamic

efficiencies. In an external energy generation system, like a reactor powered one, all

of the components from the core to the heat exchangers heating the working fluid

must operate at a higher temperature than the fluid. This severely limits the peak

cycle temperature compared to an internal combustion system. This liability can be

overcome to a certain extent by using multiple expansion turbines and designing

highly efficient heat exchangers to heat the working fluid between expansion

processes similar to reheaters in steam systems.

Typically the combustion chamber in a gas turbine involves a pressure drop of

3–5% of the total pressure. Efficient liquid salt to air heat exchangers can theoret-

ically be designed with a pressure drop of less than 1%. This allows three to five

expansion cycles to achieve a pressure drop comparable to a combustion system.

Multiple turbines operating at different pressures have been common in steam

power plants for a number of years. In this study one to five gas turbines operating

on a common shaft were considered.

Multiple expansion turbines allow a larger fraction of the heat input to be

provided near the peak temperature of the cycle. The exhaust from the last turbine

is provided to the Heat Recovery Steam Generator (HRSG ) to produce the steam

used in the Rankine bottoming cycle. The hot air after it passes through the HRSG is

exhausted to the atmosphere. A detailed comparison of this system was made with a

recuperated stand-alone Brayton cycle, and the dual cycle appears to be more

efficient for open systems.

7.5 Modeling the Rankine Cycle

The Rankine cycle was modeled with the standard set of components including the

HSRG, a steam turbine, condenser, and high-pressure pump. Multiple reheat

processes were considered. There is a slight efficiency advantage to include two

reheat processes as per a fairly standard practice in today' s power plants.

The major limitation on the size of the steam system is the enthalpy available

from high-temperature air above the pinch point where the high-pressure water

working fluid starts to vaporize. Below this point, there is still a significant enthalpy

in the air which is readily available to heat the high-pressure water. There does not

appear to be an advantage to including feed water heaters in the cycle to bring the

high-pressure water up to the saturation point. The possibility that an intercooler

could be inserted between the two stages of a split compressor was considered. The

cooling fluid for the intercooler was the high-pressure water coming out of the

water pump.

158 7 Gas Turbine Working Principals

This process would combine the function of the traditional intercooler with the

preheating of a typical feed water heater. The effect of this addition to the two

cycles had a marginal effect on the overall system efficiency and likely is not worth

the cost, or effort, to implement.

7.6 The Combined Brayton-Rankine Cycle

The combined cycle unit combines the Rankine (steam turbine) and Brayton (gas

turbine) thermodynamic cycles by using heat recovery boilers to capture the energy

in the gas turbine exhaust gases for steam production to supply a steam turbine as

shown in the Fig. 7.10 "combined cycle cogeneration unit." Process steam can be

also provided for industrial purposes.

Fossil fuel-fired (central) power plants use either steam or combustion turbines

to provide the mechanical power to electrical generators. Pressurized high-

temperature steam or gas expands through various stages of a turbine, transferring

energy to the rotating turbine blades. The turbine is mechanically coupled to a

generator, which produces electricity.

Fig. 7.10 The combined cycle Brayton and Rankine cycle cogeneration unit

7.6 The Combined Brayton-Rankine Cycle 159

The Brayton cycle efficiency is quite low primarily because a substantial amount

of the energy input is exhausted to surroundings. This exhausted energy is usually at

a relatively high temperature, and thus it can be used effectively to produce power.

One possible application is the combined Brayton Rankine cycle in which the high-

temperature exhaust gases exiting the gas turbine are used to supply energy to the

boiler of the Rankine cycle, as illustrated in Fig. 3.12 . Note that the temperature T

9

of the Brayton cycle gases exiting the boiler is less than the temperature T

3

of the

Rankine cycle steam exiting the boiler; this is possible in the counterflow heat

exchanger, the boiler.

7.7 Single and Multi-shaft Design

The gas turbine can be designed in a single or multi-shaft configuration. In the

single-shaft case, the gas turbine is designed with roughly equal pressure ratios

across all expansion stages which are mechanically coupled to the gas compressor

and generator and operate at the generator speed (normally 3600 or 1800 rpm for

60 Hz electrical systems and 3000 or 1500 rpm for 50 Hz electrical systems). In a

multi-shaft configuration, the compressor is mechanically driven by a set of expan-

sion stages sized to produce the amount of mechanical work required by the

compressor, so that this shaft is not connected to the electrical generator and can

rotate at different speeds. The air produced from this gas-generator is heated and

directed to a turbo-generator: a final expansion stage on a separate shaft that rotates

at the optimal generator speed. C ombined c ycle g as t urbine (CCGT ) power plant

suppliers configure turbine generators in a number of different arrangements.

Multi-shaft and single-shaft configurations allow customization to optimize

plant performance, capital investment, construction and maintenance access, oper-

ating convenience, and minimum space requirements.

The development of large F-class gas turbines during the past decade went hand

in hand with manufacturers' efforts to standardize c ombined c ycle p ower plant

(CCPP ) configurations, striving to best use the new technology. The single- s haft

power train ( SSPT) arrangement was first conceived for applications using gas

turbines over 250 megawatts. Only later the concept was extended to smaller

units in the range of 60 megawatts. The new SSPT arrangement allowed single

blocks of up to 450 megawatts to be built. SSPTs contributed the most to the power

plants aiming at cost savings and project time reductions and thus at lower risk. In

SSPT arrangements, the gas turbine and the steam turbine are coupled to a common

generator on a single shaft, whereas in multi- s haft p ower t rain blocks (MSPT )upto

three gas turbines and their allocated boilers and generators share a common steam

turbine (See Fig. 7.11 ). SSPT and MSPT are both built for 50 and 60 Hz markets.

The main benefits of the new concept highlighted by manufacturers are higher

operation flexibility, smaller footprint, simplified control, shorter run-up time, more

standardized peripheral systems, and higher efficiency and availability. This devel-

opment requires that, in addition to new technical issues related to the gas turbine

160 7 Gas Turbine Working Principals

design, insurers look at a great number of aspects when covering entire combined

cycle power plants.

In a multi-shaft combined cycle plant, there are generally several gas turbines

with HRSGs generating steam for a single steam turbine. The steam and gas

turbines use separate shafts, generators, set-up transformers, and so on. By com-

bining the steam production of all the HRSGs, a large steam volume enters the

steam turbine, which generally raises the steam turbine efficiency.

Modern gas turbines achieve higher output with higher exhaust temperatures.

With the large gas turbines on the market, one steam turbine per gas turbine or one

steam turbine for two gas turbines is common. See Fig. 7.12.

If one steam turbine per gas turbine is installed, the single-shaft application is the

most common solution—gas turbine and steam turbine driving the same

generator [2].

A plant with two gas turbines can be built either with two gas turbines on one

steam turbine configuration (multi-shaft) or as a plant with two gas turbines, each in

a single-shaft configuration. In either scenario usage of clutch as a synchronous

self-shifting device has a significant impact on components used in the respective

combined cycle power plant (CCPP).

A combined cycle single-shaft configuration with the generator between the two

turbines enables installation of a clutch between steam turbine and generator. This

means the clutch engages in that moment when the steam turbine speed tries to

overrun the rigidly couple gas turbine generator and disengages if the torque

transmitted from the steam turbine to generator becomes zero.

Fig. 7.11 Combined cycle

single-shaft arrangements

Fig. 7.12 Combined cycle multi shaft arrangements

7.7 Single and Multi-shaft Design 161

The clutch allows startup and operation of the gas turbine without driving the

steam turbine. This results in a lower starting power requirement and eliminates

certain safety measures for the steam turbine (e.g., cooling steam or sealing

steam) [2].

Furthermore, clutch implementation provides design opportunities for accom-

modating axial thermal expansion. The clutch itself compensates for a portion of

axial displacement, and the two thrust bearings allow selective distribution of the

remaining axial expansion (reducing tip clearance losses). In addition, it allows

more operational flexibility such as gas turbine simple cycle operation or early

preventive maintenance (PM) activities on gas turbine during steam turbine

cool down.

Generations of combined cycle power plant equipment that are manufactured by

General Electric are also divided into two basic configurations:

1. Single shaft

2. Multiple shaft

The single-shaft combined cycle system consists of one gas turbine, one steam

turbine, one generator, and one H eat R ecovery S team G enerator (HRSG) , with the

gas turbine and steam turbine coupled to a single generator in a tandem

arrangement [3].

Single shaft arrangements where a gas turbine and a steam turbine drive a single

generator are often preferred because they offer a more compact plant at a lower

cost. Many include an SSS (name of manufacture in United Kingdom) clutch to

disconnect the steam turbine and to allow the gas turbine/generator to be operated

separately. See Fig. 7.13.

Advantages of this arrangement are as follows:

A. Simple startup

• Standard gas turbine (GT) start

• Reduced time to generation

Fig. 7.13 Single shaft

CCGT arrangement using

an SSS clutch

162 7 Gas Turbine Working Principals

• No cooling steam required

• Reduced starting power

• Reduced emissions

• Standardized design

• Simplified torsion analysis

B. Increased flexibility

• Simplified commissioning

• Steam turbine trips do not stop power generation

• Maintenance of gas turbine (GT) is possible during steam generation

(SG) cooling

C. Optimized shutdown

• Shutdown steam turbine (ST) at reduced gas turbine (GT) power

Multi-shaft combined cycle systems have one or more gas turbine generators and

HRSGs that supply steam through a common heater to a separate single steam

turbine generator unit. Both configurations perform their specific functions, but the

single-shaft configuration excels in the baseload and midrange power generation

applications.

The multi-shaft combined cycle system configuration is most frequently applied

in phased installations in which the gas turbines are installed and operated prior to

the steam cycle installation and where it is desired to operate the gas turbines

independent of the steam system. The multi-shaft configuration was applied most

widely in the early history of heat recovery combined cycles primarily because it

was the least departure from the familiar conventional steam power plants. The

single-shaft combined cycle system has emerged as the preferred configuration for

single phase applications in which the gas turbine and steam turbine installation and

commercial operation are concurrent.

Multi-shaft systems have one or more gas turbine-generators and HRSGs that

supply steam through a common header to a separate single steam turbine-

generator. In terms of overall investment, a multi-shaft system is about 5% higher

in costs.

The primary disadvantage of multiple-stage combined cycle power plant is the

number of steam turbines, condensers and condensate systems, and perhaps the

cooling towers and circulating water systems required by the bottoming cycle.

A Heat Recovery Steam Generator (HRSG) is a heat exchanger or series of heat

exchangers that recovers heat from a hot gas stream and uses that heat to produce

steam for driving steam turbines or as process steam in industrial facilities or as

steam for district heating.

An HRSG is an important part of a combined cycle power plant (CCPP) or a

cogeneration power plant [4 ]. In both of those types of power plants, the HRSG uses

the hot flue gas at approximately 500–650 C from a gas turbine to produce high-

pressure steam. The steam produced by an HRSG in a gas turbine combined cycle

power plant is used solely for generating electrical power. However, the steam

7.7 Single and Multi-shaft Design 163

produced by an HRSG in a cogeneration power plant is used partially for generating

electrical power and partially for district heating or for process steam. See Fig. 7.14 .

The combined cycle power plant, schematically depicted in Fig. 7.15 ,isso

named because it combines the Brayton cycle for the gas turbine and the Rankine

cycle for the steam turbines. About 60% of the overall electrical power generated in

a CCPP is produced by an electrical generator driven by the gas turbine and about

40% is produced by another electrical generator driven by the high-pressure and

low-pressure steam turbines. For large-scale power plants, a typical CCPP might

use sets consisting of a gas turbine driving a 400 MW electricity generator and

steam turbines driving a 200 MW generator (for a total of 600 MW), and the power

plant might have two or more such sets.

The primary components of the heat exchangers in an HRSG are the economizer,

the evaporator and its associated steam drum, and the superheater as shown in

Fig. 7.16 . An HRSG may be in horizontal ducting with the hot gas flowing

horizontally across vertical tubes as in Fig. 7.16 or it may be in vertical ducting

with the hot gas flowing vertically across horizontal tubes. In either horizontal or

vertical HRSGs, there may be a single evaporator and steam drum or there may be

two or three evaporators and steam drums producing steam at two or three different

pressures. Figure 7.16 depicts an HRSG using two evaporators and steam drums to

produce high-pressure steam and low-pressure steam, with each evaporator and

steam drum having an associated economizer and superheater. In some cases,

supplementary fuel firing may be provided in an additional section at the front

end of the HRSG to provide additional heat and higher temperature gas.

Fuel

No.3

No.1&2

Electricity

Gas Turbine

Fuel

Generator × 2 Gas Turbine × 2

Cogeneration

Steam

Extraction

Condensing

Steam Turbin

HRSG with Supplimental firing × 2

Heat Recovery Steam Generato

Fig. 7.14 Combined cycle power plant with multi shaft configuration

164 7 Gas Turbine Working Principals

There are a number of other HRSG applications. For example, some gas turbines

are designed to burn liquid fuels (rather than gas) such as petroleum naphtha or

diesel oil [5 ], and others burn the syngas (synthetic gas) produced by coal gasifi-

cation in an integrated gasification combined cycle plant commonly referred to as

Fig. 7.15 HRSG for multi

shaft combined cycle power

plant

HP steam

to turbine

SH EVAP

Hot combustion gas

from gas turbine

ECO

HP

Steam drum LP steam

to turbine

LP

Steam drum

SH EVAP ECO

Feedwater

Flue gas stack

ECO

ECO = EconomizerEVAP = evaporator

HP = High Pressure

LP = Low Pressure

SH = superheater

= Hot

as ductin

Fig. 7.16 Heat Recovery Steam Generator (HRSG)

7.7 Single and Multi-shaft Design 165

an IGCC

1

plant. As another example, a combined cycle power plant may use a

diesel engine rather than a gas turbine. In almost all such other applications, HSRGs

are used to produce steam to be used for power generation.

7.8 Working Principle of Combined Cycle Gas Turbine

(CCGT)

The first step is the same as the simple cycle gas turbine plant. An open cycle gas

turbine has a compressor, a combustor, and a turbine. For this type of cycle, the

input temperature to the turbine is very high. The output temperature of the flue

gases is also very high. This is high enough to provide heat for a second cycle which

uses steam as the working medium, i.e., thermal power station. See Fig. 7.17.

1. Air Inlet

This air is drawn though the large air inlet section where it is cleaned, cooled, and

controlled. Heavy-duty gas turbines are able to operate successfully in a wide

variety of climates and environments due to inlet air filtration systems that are

specifically designed to suit the plant location.

Under normal conditions, the inlet system has the capability to process the air by

removing contaminants to levels below those that are harmful to the compressor

and turbine.

In general the incoming air has various contaminants. They are:

In gaseous state, contaminants are:

• Ammonia

• Chlorine

• Hydrocarbon gases

• Sulfur in the form of H

2

S, SO

2

• Discharge from oil cooler vents

In liquid state contaminants are:

• Chloride salts dissolved in water (sodium, potassium)

• Nitrates

• Sulfate

• Hydrocarbons

In solid state contaminants are:

• Sand, alumina, and silica

• Rust

1

IGCC is a process that turns coal into a clear fuel that is used for more efficient power generation.

Gasification turns coal into a synthetic gas—or syngas—so that we can remove emissions like

SOX (Sarbanes-Oxley compliance), mercury, and particulate matter.

166 7 Gas Turbine Working Principals

• Road dust, alumina, and silica

• Calcium sulfate

• Ammonia compounds from fertilizer and animal feed operations

• Vegetation, airborne seeds

Corrosive agents:

• Chlorides, nitrates, and sulfates can deposit on compressor blades and may

result in stress corrosion attack and/or cause corrosion pitting. Sodium and

potassium are alkali metals that can combine with sulfur to form a highly

corrosive agent and that will attack portions of the hot gas path. The

contaminants are removed by passing through various types of filters

which are present on the way.

• Gas phase contaminants such as ammonia or sulfur cannot be removed by

filtration. Special methods are involved for this purpose.

2. Turbine Cycle

The air is purified then compressed and mixed with natural gas and ignited, which

causes it to expand. The pressure created from the expansion spins the turbine

blades, which are attached to a shaft and a generator, creating electricity.

In the second step, the heat of the gas turbine' s exhaust is used to generate steam by

passing it through a Heat Recovery Steam Generator (HRSG) with a live steam

temperature between 420 C and 580 C.

Turbine

Turbine

Gas Air

Alternator

Flue

HRSG

Exhaust

gases

Steam

Boiler feed pump

Feed water

Cooling

water

Condenser

Alternator

Fig. 7.17 Working principle of combined cycle gas turbine (CCGT) plant

7.8 Working Principle of Combined Cycle Gas Turbine (CCGT) 167

3. Heat Recovery Steam Generator

In the Heat Recovery Steam Generator, highly purified water flows in tubes, and the

hot gases pass around them to produce steam. The steam then rotates the steam

turbine and coupled generator to produce electricity. The hot gases leave the

HRSG at around 140 centigrade and are discharged into the atmosphere.

The steam condensing and water pump systems are the same as in the steam power

plant.

4. Typical Size and Configuration of CCGT

The combined cycle system includes single-shaft and multi-shaft configurations.

The single-shaft system consists of one gas turbine, one steam turbine, one

generator, and one Heat Recovery Steam Generator (HRSG), with the gas

turbine and steam turbine coupled to the single generator on a single shaft.

Multi-shaft systems have one or more gas turbine-generators and HRSGs that

supply steam through a common header to a separate single steam turbine-

generator. In terms of overall investment, a multi-shaft system is about 5%

higher in costs.

5. Efficiency of CCGT Plant

Roughly the steam turbine cycle produces one third of the power and gas turbine

cycle produces two thirds of the power output of the CCPP. By combining both

gas and steam cycles, high input temperatures and low output temperatures can

be achieved. The efficiency of the cycles adds, because they are powered by the

same fuel source.

Note

To increase the power system efficiency, it is necessary to optimize the

HRSG, which serves as the critical link between the gas turbine cycle and

the steam turbine cycle with the objective of increasing the steam turbine

output. HRSG performance has a large impact on the overall performance of

the combined cycle power plant.

The electric efficiency of a combined cycle power station may be as high as 58%

when operating new and at continuous output which are ideal conditions. As

with single cycle thermal units, combined cycle units may also deliver low

temperature heat energy for industrial processes, district heating, and other

uses. This is called cogeneration and such power plants are often referred to as

a combined heat and power (CHP) plant.

The efficiency of CCPT is increased by supplementary firing and blade cooling.

Supplementary firing is arranged at HRSG, and in gas turbine a part of the

compressed air flow bypasses and is used to cool the turbine blades. It is

necessary to use part of the exhaust energy through gas to gas recuperation.

Recuperation can further increase the plant efficiency, especially when gas

turbine is operated under partial load.

168 7 Gas Turbine Working Principals

6. Fuels for CCPT Plants

The turbines used in combined cycle plants are commonly fueled with natural gas,

and it is more versatile than coal or oil and can be used in 90% of energy

applications. Combined cycle plants are usually powered by natural gas,

although fuel oil, synthesis gas, or other fuels can be used.

7. Emission Control

Selective catalytic reduction (SCR):

• To control the emissions in the exhaust gas so that it remains within

permitted levels as it enters the atmosphere, the exhaust gas passes through

two catalysts located in the HRSG.

• One catalyst controls carbon monoxide (CO) emissions and the other

catalyst controls oxides of nitrogen (NOx) emissions. Aqueous ammonia,

in addition to the SCR (a mixture of 22% ammonia and 78% water), is

injected into system to even further reduce levels of NOx.

Advantages of combined cycle power plants are:

1. Fuel efficiency

In conventional power plants, turbines have a fuel conversion efficiency of

33% which means two thirds of the fuel is burned to drive the turbine off. The

turbines in combined cycle power plant have a fuel conversion efficiency of 50%

or more, which means they burn about half amount of fuel as a conventional

plant to generate same amount of electricity.

2. Low capital costs

The capital cost for building a combined cycle unit is two thirds the capital

cost of a comparable coal plant.

3. Commercial availability

Combined cycle units are commercially available from suppliers anywhere in

the world. They are easily manufactured, shipped, and transported.

4. Abundant fuel source

The turbines used in combined cycle plants are fueled with natural gas, which

is more versatile than a coal or oil and can be used in 90% of energy publica-

tions. To meet the energy demand nowadays, plants are not only using natural

gas but also using other alternatives like biogas derived from agriculture.

5. Reduced emission and fuel consumption

Combined cycle plants use less fuel per kWh and produce fewer emissions

than conventional thermal power plants, thereby reducing the environmental

damage caused by electricity production. Comparable with coal-fired power

plant, burning of natural gas in CCPT is much cleaner.

6. Potential applications in developing countries

The potential for combined cycle plant is with industries that require elec-

tricity and heat or stem.

Disadvantages of combined cycle power plants are:

1. The gas turbine can only use natural gas or high-grade oils like diesel fuel.

2. Because of this the combined cycle can be operated only in locations where

these fuels are available and cost effective.

7.8 Working Principle of Combined Cycle Gas Turbine (CCGT) 169

7.9 Gas Turbine Technology and Thermodynamics

The turbine entry temperature, T

c

, is fixed by materials technology and cost. (If the

temperature is too high, the blades fail.) Figures 7.18 and 7.19 show the progression

of the turbine entry temperatures in aero engines. Figure 7.18 is from Rolls-Royce

and Fig. 7.19 is from Pratt & Whitney. Note the relation between the gas temper-

ature coming into the turbine blades and the blade melting temperature.

For a given level of turbine technology (in other words given maximum tem-

perature), a design question is:

• What should the compressor temperature ratio across compressor between point

aand b( TR) be?

TR ¼ T

b

/T

a

• What criterion should be used to decide this?

• Maximum thermal efficiency?

• Maximum work?

We examine this issue below using Fig. 7.20 as baseline guide.

The problem is posed in Fig. 7.20 , which shows two Brayton cycles. For

maximum efficiency, we would like TR as high as possible. This means that the

1950 1960 1960

900

1980

1000

1100

1200

1300

1400

1500

2000

2100

2200

2300

1900

1800

1700

1600

1990 2000 2010

1940

Engine TET

Material capability

Year

Take off turbine entry temperature (K)

Demonstrator

Capability

Cooled

turbine

blades

Uncooled

turbine

blades

Derwent

w1

Dart Avon

Wrought alloys

Conventionally cast alloys

DS cast alloys

SX cast

alloys

Ceramics

Trent

RB211-524G2

RB211-524B4

RB211-22C

Conway

Spery

RB211-524G/H

RB211-535E4

Fig. 7.18 Rolls-Royce high-temperature technology (Courtesy of Rolls-Royce)

170 7 Gas Turbine Working Principals

compressor exit temperature approaches the turbine entry temperature. The net-

work will be less than the heat received; as T

b

!T

c

the heat received approaches

zero and so does the network.

The network in the cycle can also be expressed as R Pdυ , evaluated in traversing

the cycle. This is the area enclosed by the curves, which is seen to approach zero as

T

b

!T

c

.

Rotor Inlet gas Temprature (°F)

Film

convection Advanced

cooling

Single

crystal

material

family

00.2 0.4 0.6 0.8 1.0

Convection

Solid

1800

2600

3800

3400

4200

3000

2200

Turbine material

melt temperature

Coolant effectiveness = T gas – Tmaterial

Tgas – Tcoolant

Fig. 7.19 Turbine blade cooling technology (Courtesy of Pratt & Whitney)

Fig. 7.20 Efficiency and work of two Brayton cycle engines

7.9 Gas Turbine Technology and Thermodynamics 171

The conclusion from either of these arguments is that a cycle designed for

maximum thermal efficiency is not very useful in that the work (power) we get

out of it is zero [6].

A more useful criterion is that of maximum work per unit mass (maximum

power per unit mass flow). This leads to compact propulsion devices. The work per

unit mass is given by:

Work= Unit Mass ¼ cp Tc T b

ðÞ Tb Ta

ðÞ ½ð 7:1Þ

where T

c

is the maximum turbine inlet temperature (a design constraint) and T

a

is

atmospheric temperature. The design variable is the compressor exit temperature,

T

b

, and to find the maximum as this is varied, we differentiate the expression for

work with respect to T

b

:

dWork

dTb ¼ c p

dTc

dTb 1 dT d

dTb þ dT a

dTb



ð7:2Þ

The first and the fourth terms on the right-hand side of the above equation are

both zero (the turbine entry temperature is fixed, as is the atmospheric temperature).

The maximum work occurs where the derivative of work with respect to T

b

is zero

and it can be seen as

dWork

dTb ¼0¼ 1dTd

dTb ð7:3Þ

To use Eq. 7.3 , we need to relate T

d

and T

b

. But we know that

Td

Ta ¼ T c

Tb

or Td ¼ T a T c

Tb ð7:4Þ

Hence, we can write:

dTd

dTb ¼ T a T c

T2

bð7:5Þ

Plugging Eq. 7.5 for the derivation into Eq. 7.3 gives the compressor exit

temperature for maximum work as Tb ¼ ffiffiffiffiffiffiffiffiffiffi

Ta Tc

p. In terms of temperature ratio,

we have

Compressor temperature ratio for maximum work :T b

Ta ¼ ffiffiffiffiffi

Tc

Tc

rð7:6Þ

The condition for maximum work in a Brayton cycle is different than that for

maximum efficiency. The role of the temperature ratio can be seen if we examine

the work per unit mass which is delivered at this condition:

Work= Unit Mass ¼cp Tc ffiffiffiffiffiffiffiffiffiffi

Ta Ta

p Ta Ta

ffiffiffiffiffiffiffiffiffiffi

Ta Tc

pþTa



ð7:7Þ

Rationing all temperatures to the engine inlet temperature,

172 7 Gas Turbine Working Principals

Work= Unit Mass ¼cp Ta

Tc

Ta 2ffiffiffiffiffi

Tc

Ta

rþ1



ð7:8Þ

To find the power the engine can produce, we need to multiply the work per unit

mass by the mass flow rate:

Power ¼ _

mc

pT a

Tc

Ta 2ffiffiffiffiffi

Tc

Ta

rþ1



Maximum power for an ideal Brayton cycle

ð7: 9 Þ

The units are : kg

s

J

kg KK¼ J

s¼ Watts

The trend of work output versus compressor pressure ratio, for different tem-

perature ratios, TR ¼ T

c

/T

a

, is shown in Fig. 7.21.

Figure 7.22 shows the expression for power of an ideal cycle compared with data

from actual jet engines. Figure 7.22a shows the gas turbine engine layout including

the core (compressor, burner, and turbine). Figure 7.22b shows the core power for

a number of different engines as a function of the turbine rotor entry temperature.

Fig. 7.21 Trend of cycle work with compressor pressure ratio for different temperature ration

TR ¼ T

c

/T

a

7.9 Gas Turbine Technology and Thermodynamics 173

The equation in the figure for horsepower (HP) is the same as that which we just

derived, except for the conversion factors. The analysis not only shows the quali-

tative trend very well but captures much of the quantitative behavior too.

A final comment (for this section) on Brayton cycles concerns the value of the

thermal efficiency, which we will discuss in the next following chapter with its

supporting computer programming that is developed by (Zohuri and McDaniel) at

university of New Mexico, Nuclear Engineering Department. The Brayton cycle

thermal efficiency contains the ratio of the compressor exit temperature to atmo-

spheric temperature, so that the ratio is not based on the highest temperature in the

cycle, as the Carnot efficiency is. For a given maximum cycle temperature, the

Brayton cycle is therefore less efficient than a Carnot cycle.

References

1. B. Zohuri, Innovative combined Brayton open cycle systems for the next generation nuclear

power plants, PhD Dissertation, Nuclear Engineering Department, University of New Mexico,

2014

2. K. Rolf, F. Hannemann, F. Stirnimann, B. Rukes, Combined-cycle gas & steam turbine power

plants, 3rd edn. (PennWell Publication, Tulsa, 2009)

3. L.O. Tomlinson, S. McCullough, Single shaft combined cycle power generation system (Gen-

eral Electric Power System, Schenectady, NY) GER-3767C

4. P.C. Putnam, Energy in the future , Ch 6 (D. Van Nostrand Co., Inc., Princeton, 1953); see also

R.D. Nininger et al., Energy from uranium and coal reserves, U.S. AEC Report TID-8207

(1960)

5. M. Boyce, Gas turbine engineering handbook , 2nd edn. (Gulf Professional Publishing, Boston,

2002.) ISBN 0-88415732-6

6. Douglas Quattrochi 2006-08-06, http://web.mit.edu/16.unified/www/SPRING/propulsion/

notes/node27.html

7. B.L. Koff, Spanning the Globe with Jest Propulsion AIAA Paper 2987, AIAA Annual Meeting

and Exhibit, (1991)

8. C.E. Meece, Gas Turbine Technology of the Future, International Symposium on Air Breathing

Engines, paper 95-7006, (1995)

Fig. 7.22 Aero engine core power ( a ) Gas turbine engine cycle [7 ]. ( b) Core power vs. turbine

entry temperature [8]

174 7 Gas Turbine Working Principals

... The purpose of the gas turbine determines the design so that the most desirable energy form is maximized. Gas turbines are used to power aircraft, trains, ships, electrical generators, or even tanks [6,7]. ...

The present article explains the modeling of a Gas Turbine system; the mathematical modeling is based on fluid mechanics applying the principal energy laws such as Euler's Law, Newton's second Law and the first thermodynamic law to obtain the equations for mass, momentum and energy conservation; expressed as the continuity equation, the Navier-Stokes equation and the energy conservation using Fourier's Law. The purpose of this article is to establish a precise mathematical model to be applied in control applications, for future works, within industry applications.

... A gas turbine has a typical configuration comprising a compressor and turbines fixed together on a single shaft, which is connected to a generator [5]. Compressed air, at a typical pressure of 14 atm, is directed into the combustion section where the fuel is injected and burned and thus reacts with the compressed air. ...

In the gas-turbine research field, superalloys are some of the most widely used materials as they offer excellent strength, particularly at extreme temperatures. Vital components such as combustion liners, transition pieces, blades, and vanes, which are often severely affected by wear, have been identified. These critical components are exposed to very high temperatures (ranging from 570 to 1300 • C) in hot-gas-path systems and are generally subjected to heavy repair processes for maintenance works. Major degradation such as abrasive wear and fretting fatigue wear are predominant mechanisms in combustion liners and transition pieces during start-stop or peaking operation, resulting in high cost if inadequately protected. Another type of wear-like erosion is also prominent in turbine blades and vanes. Nimonic 263, Hastelloy X, and GTD 111 are examples of superalloys used in the gas-turbine industry. This review covers the development of hardface coatings used to protect the surfaces of components from wear and erosion. The application of hardface coatings helps reduce friction and wear, which can increase the lifespan of materials. Moreover, chromium carbide and Stellite 6 hardface coatings are widely used for hot-section components in gas turbines because they offer excellent resistance against wear and erosion. The effectiveness of these coatings to mitigate wear and increase the performance is further investigated. We also discuss in detail the current developments in combining these coating with other hard particles to improve wear resistance. The principles of this coating development can be extended to other high-temperature applications in the power-generation industry.

The major chunk of power generation in India is done by thermal power plants spread across the nation. These plants are situated near to the coal reserves and near major ports. The working of thermal power plant along with major thermal plants of India is discussed. Indian motherland is blessed with huge potential of hydropower which stands second in producing the highest amount of electric power after coal-based plants. Renewable energy is the fastest-growing in this sector. Solar and wind energy-based power plants are discussed. The promising source for future energy is nuclear power plants. Hence, due importance has been paid to these plants. Specific challenges and opportunities in operating the various power plants are also discussed. India, as a vast land, necessitates bulk power transmission corridors to connect generating stations that are located in close proximity with the sources to the load centres and it is one of the world leaders in this field. This necessitates a discussion of various bulk power transmission lines.

  • Osama Khayal Osama Khayal

مقـدمة الحمد لله والصلاة والسلام علي رسوله محمد صلى الله عليه وسلم وبعد: إنَّ مؤلِّف هذا الكتاب إيماناً منه بالدور العظيم والمقدَّر للأستاذ الجامعي في إثراء حركة التأليف والتعريب والترجمة يأمل أن يفي هذا الكتاب بمتطلبات برامج البكالوريوس والدبلوم العام والمتوسط لطلاب وفنيي الهندسة الميكانيكية وهندسة الإنتاج أو التصنيع. يتفَّق هذا الكتاب لغوياً مع القاموس الهندسي الموَّحد السوداني، ويُعد الكتاب مرجعاً في مجاله حيث يمكن أن يستفيد منه الطالب والمهندس والباحث ويعتبر الكتاب مقتبساً من مذكرات مؤلفه في تدريسه لهذا المقرر لفترة لا تقل عن عشرون عاماً. يهدف هذا الكتاب لتأكيد أهمية استخدام التوربينات الغازية في حياتنا المعاصرة في تطبيقات هندسية عديدة من بينها توليد الطاقة الكهربائية، الطائرات النفاثة وفي العديد من المنشآت الهندسية. يشتمل هذا الكتاب على خمسة فصول حيث يستعرض الفصل الأول الدورة الأساسية للتوربينة الغازية من حيث مكوناتها والمخطط البياني لدرجة الحرارة ضد القصور الحراري. يشتمل الفصل الثاني على العديد من الأمثلة المحلولة المرتبطة بالدورة الأساسية للتوربينة الغازية مع بيان المخطط الوظيفي ومخطط تفاوت القصور الحراري مع درجة الحرارة. يتناول الفصل الثالث تعديلات الدورة الأساسية للتوربين الغازي التي تشتمل على إضافة مبرِّد بيني (intercooler) لتبريد الهواء بين مرحلتي الضاغط، سخَّان او غرفة احتراق ثانية (heater or second combustion chamber) لزيادة الحرارة المكتسبة في الدورة، ومبادل حراري (heat exchanger) للاستفادة من طاقة المحتوى الحراري العالية المغادرة للتوربين. يشتمل الفصل الرابع على مثال شامل يتطرق لجميع تعديلات الدورة الأساسية للتوربين الغازي. أما الفصل الخامس فيستعرض العديد من المسائل الإضافية في التوربينات الغازية. إنَّ الكاتب يأمل أن يُساهم هذا الجهد المتواضع في إثراء المكتبة الجامعية داخل السودان وخارجه في هذا المجال من المعرفة ويأمل من القارئ بضرورة إرسال تغذية راجعة إن كانت هنالك ثمة أخطاء حتى يستطيع الكاتب تصويبها في الطبعة التالية للكتاب. اللهم لا سهل إلاَّ ما جعلته سهلاً وأنت تجعل الحزن إذا شئت سهلاً والله ولي التوفيق المؤلف أسامة محمد المرضي سليمان قسم الهندسة الميكانيكية كلية الهندسة والتقنية جامعة واي النيل ديسمبر 2016م

  • M.P. Boyce

The Gas Turbine Engineering Handbook has been the standard for engineers involved in the design, selection, and operation of gas turbines. This revision includes new case histories, the latest techniques, and new designs to comply with recently passed legislation. By keeping the book up to date with new, emerging topics, Boyce ensures that this book will remain the standard and most widely used book in this field.The new Third Edition of the Gas Turbine Engineering Hand Book updates the book to cover the new generation of Advanced gas Turbines. It examines the benefit and some of the major problems that have been encountered by these new turbines. The book keeps abreast of the environmental changes and the industries answer to these new regulations. A new chapter on case histories has been added to enable the engineer in the field to keep abreast of problems that are being encountered and the solutions that have resulted in solving them.

Single shaft combined cycle power generation system (General Electric Power System

  • L O Tomlinson
  • S Mccullough

L.O. Tomlinson, S. McCullough, Single shaft combined cycle power generation system (General Electric Power System, Schenectady, NY) GER-3767C

Innovative combined Brayton open cycle systems for the next generation nuclear power plants, PhD Dissertation

  • B Zohuri

B. Zohuri, Innovative combined Brayton open cycle systems for the next generation nuclear power plants, PhD Dissertation, Nuclear Engineering Department, University of New Mexico, 2014

Princeton, 1953); see also R.D. Nininger et al., Energy from uranium and coal reserves

  • P C Putnam

P.C. Putnam, Energy in the future, Ch 6 (D. Van Nostrand Co., Inc., Princeton, 1953); see also R.D. Nininger et al., Energy from uranium and coal reserves, U.S. AEC Report TID-8207 (1960)

Spanning the Globe with Jest Propulsion AIAA Paper 2987

  • B L Koff

B.L. Koff, Spanning the Globe with Jest Propulsion AIAA Paper 2987, AIAA Annual Meeting and Exhibit, (1991)