Literature study Essay – Grand Paper Writers

Requirements and

Literature study

The history of the gas turbine

Looking back at the history, the idea of the gas and steam turbines dates back to

1791 when John Barber’s patent described new

uid gasses as a potential energy

source (Giampaolo, 2006). The invention of John Barber may be considered a

gas turbine, where the gas produced by heating the coal was mixed with air,

then compressed and after that burnt. The result of this operation was a high

speed jet that had an e ect on the radial blades of the turbine wheel rim (Day,

1980). Nonetheless, Barber’s idea of a gas turbine as the ideas of his predecessors

(Giovanni Branca’s impulse steam turbine – 1629, Leonardo da Vinci’s smoke

mill” – 1550, and Hero of Alexandria’s reaction steam turbine – 130 BC (Usher,

1988)) were considered only ideas and there is no evidence of a working hardware

until the late 19 th

century (Giampaolo, 2006).

However, throughout the next centuries, new ideas were put into practice

which led to the development of a working hardware by the end of the 19 th

century. In 1903, Rene Armengaud and Charles Lemale produced the

rst gas

turbine, which was using a Rateau rotary compressor and a Curtis velocity com-

pounded steam turbine (Giampaolo, 2006). The development of more powerful

and more e cient gas turbines continued and new types of fuels were researched.

Therefore, in the 1990s, it was found that after coal, natural gas is the next in

line as the most important fossil fuel for generating electricity (Breeze, 2016).

This new discovery o ered a high-e ciency power plant, which were cheap to

build and could produce cheap electricity, depending on the price of the gas.

They were more sustainable, as the emissions of carbon dioxide were lower than

the coal-

red power plants. The use of natural gas for power generation had a continuously growth

throughout the 21 st

century (Breeze, 2016). The high demand of natural gas

for power generation had been in

uenced by the cost, and climate change. The

combustion of natural gas produced less carbon dioxide which represented an

ideal solution to meet the limits implemented for the carbon dioxide emissions.

Due to the developments made, at the moment, the gas turbine represents the

most important machine generating electricity from natural gas.

The working principle of a gas turbine

Gas turbines are engines where the chemical energy of the fuel is converted into

mechanical energy. There are two types of gas turbines, the power generation

gas turbines, which produce shaft energy, and gas turbines which produce kinetic

energy, in terms of thrust, used to propel an aircraft (Schobeiri, 2017). The gas

turbine has three main components, namely the compressor, the combustor and

the turbine. A heavy duty power generation gas turbine is shown in

g. 1. Figure 1: Heavy duty power generation gas turbine(Schobeiri, 2017)

The compression system in a gas turbine generates, in the most e cient way,

the pressure ratio required by the cycle. It represents the

rst signi

cant part

of the Brayton cycle, where the rotating blades of the compressor apply power

to the working

uid. The main elements of a compressor are the moving rotor

blade followed by a stator or vane. The blade is driven by the shaft using power

from the turbine rotor blades (Kurzke and Halliwell, 2018).

The purpose of the combustion process is to increase the temperature of the

air

ow by burning the fuel. Combustion e ciency is an important aspect in

the design process, and it is essential to be taken into consideration with respect

to the operating variables of air pressure, temperature and mass

ow rate. The

most popular model of the combustion process is based on the notion that the

total time required to burn a liquid fuel is represented by the sum of the times

required for fuel evaporation, mixing of fuel vapor with air and combustion

products, and chemical reaction (Lefebvre, 1998). The turbine extracts the hot gasses created from the ignited mixture, in the

combustion chamber, and it transforms it into work. This work can be used to

generate electrical power or thrust for an aircraft.

The future of the gas turbine

Due to the environmental crisis that the human race is facing, the demand

for sustainable products increased signi

cantly over the past years. The big

industries have to adapt to the new regulations and adopt more sustainable

and environmentally friendly ethics. Therefore, the gas turbines industries is

looking into alternative fuels, in order to have a lower carbon footprint. The

ideal situation is to be able to produce energy from renewable sources, such as

wind, sun, water or biomass. An alternative solution is using gas, as it is much

easier to store, and convert it into energy. Sustainability is a very important

topic at the moment and many resources are used by the industries in order to

lower the overall emissions.

Gas Turbines with Heat exchanger

Fuel burn is of high importance at the moment due to the e ect of the carbon

dioxide and other emissions of the environment. These emissions together with

noise generations have tougher regulations nowadays and they are monitored

worldwide to make sure they comply to the international rules that govern

emissions (Kurzke and Halliwell, 2018). The amount of fuel needed in gas

turbines can be reduced signi

cantly by introducing a heat exchanger. This is

used to transfer a part of the exhaust energy to the entrance of the combustion

chamber (Kurzke and Halliwell, 2018). A heat exchanger is a device used for the transfer of thermal energy, also

known as enthalpy, between two or more

uids, a solid surface and a

uid or

solid particulates and a

uid, at di erent temperatures and in thermal contact.

A heat exchanger is classi

ed according to transfer processes, number of

uids,

degree of surface compactness, construction features,

ow arrangements and

heat transfer mechanisms (Shah and Sekulic, 2003). Usually, in a heat exchanger there is no external heat or work interactions.

The standard use is represented by the heating or cooling of a

uid steam, evap-

oration or condensation of

uid steams, recovering or rejecting heat or sterilize,

distill, concentrate, crystallize or control of a process

uid. Even though for

some heat exchangers the

uids exchanging heat are in direct contact, in most

machines, the

uids are being separated by a heat transfer surface so they do

not mix or leak. These are named direct transfer typeorrecuperators . On the

other hand, the machines where discontinuous heat exchange between the hot

and cold

uids is produced, by means of energy storage and release through the

surface, are known as indirect transfer typeorregenerators (Shah and Sekulic,

2003).

The most frequent types of heat exchangers are shell-and-tube exchangers,

automobile radiators, condensers, evaporators, air preheaters and cooling tow-

ers. Another type is the sensible heat exchanger, which implies that there is no

change of phase in any of the

uids involved. In a heat pipe exchanger, the heat

pipe promotes the transfer of heat by condensation, evaporation and conduction

of the working

uid inside the heat pipe (Shah and Sekulic, 2003).

The elements of a heat exchanger are divided in two categories, namely heat

transfer elements , such as core or matrix containing the heat transfer surface,

and

uid distribution elements , such as headers, manifolds, tanks, inlet and

outlet nozzles or pipes, or seals. The surface that is in direct contact with the

uids is called the heat transfer surface. This is also the surface through which

heat is transfer by conduction. The surface in direct contact to the

uids is

the primary anddirect surface . To increase the surface area, extensions can be

connected to the direct surface, these are called extented,secondary orindirect

surface , and they are referred to as

ns. The implementation of

ns increases

the total heat transfer from the surface by reducing the thermal resistance (Shah

and Sekulic, 2003). Besides the important role that heat exchanges is playing in the process,

power, petroleum, transportation, air-conditioning, refrigeration, cryogenic, heat

recovery, alternative fuel and manufacturing industries; they are also essential

for industrial products available on the market. These di erent type of ex-

chagers can be categories is numerous ways, according to the transfer process,

number of

uids and heat transfer mechanisms (Shah and Sekulic, 2003).

Tube-Fin Heat Exchangers

In a conventional tube-

n heat exchanger, the transfer of heat between two

uids happens through the tube wall. However, in a heat pipe exchanger (a

specialized type of tubular heat exchanger), tubes closed at both ends act as

an wall and the transfer of heat between

uids happens through this dividing

wall” by conduction, evaporation and condensation of the heat pipe

uid (Shah

and Sekulic, 2003).

Conventional Tube-Fin Exchangers

In a gas-to-liquid heat exchanger, the heat transfer coe cient of the liquid is

usually one order of magnitude higher than the on of the gas. Therefore, to have

balance regarding the thermal conductivity on both sizes,

ns are used on the

gas size in order to increase the surface area. Moreover, if one

uid has a higher

pressure, it is more economical to implement tubes. The most common tubes are

round and rectangular. Usually the

ns are places on the outside, attached to

the tubes by a tight mechanical

t, tension winding, adhesive bonding, soldering,

brazing, welding, or extrusion (Shah and Sekulic, 2003). Tube-

n exchangers fall under di erent categories, depending on the

type. These categories are:

nned tube exchanger, shown in

gure

g. 2, having

normal

ns on individual tubes; tube-

n exchangers, shown in

g. 3, having

ns; longitudinal

ns on individual tubes, shown in

g. 4 (Shah and Sekulic,

2003).

Figure 2: Individually

nned tubes (Shah and Sekulic, 2003)

Figure 3: Flat (continuous)

ns on an array of tubes. The

ns are shown as

plain

ns, but they can be wavy, louvered, or interrupted. (Shah and Sekulic,

2003)

Figure 4: Longitudinal

ns on individual tubes: (a) continuous plain; (b) cut

and twisted; (c) perforated; (d) internal and external longitudinal

ns. (Shah

and Sekulic, 2003)

A heat exchanger with

ns is usually cheaper per unit surface area of heat

transfer due to its simple and mass-production design features. Longitudinal

are commonly used for condensation and for viscous liquids in double-pipe heat

exchangers. Shell-and-tube exchangers may use low

nned tubes to increase the

surface area on the shell side when the shell-side heat transfer coe cient is low,

in comparison to the tube-side coe cient, such as with highly viscous liquids,

gases, or condensing refrigerant vapors. Tube-

n exchangers can withstand

very high pressures on the tube side. The temperature is limited by the type

of bonding, materials employed, and material thickness. Tube-

n exchangers

usually are less compact than plate-

n units (Shah and Sekulic, 2003).

An air-cooled exchanger is a tube-

n exchanger where hot processed

uids

ow inside the tubes, and the atmospheric circulated outside by forced or in-

duced draft over the extended surface. When used in a cooling tower, and the

process

uid is water, it is called dry cooling tower. This type of exchanger has

shallow tube bundles and large face area (Shah and Sekulic, 2003).

Plate-and-frame heat exchangers

The keystone in the reduction of fuel consumption and greenhouse gas emis-

sions is represented by e cient heat recuperation. The plate heat exchangers

are used as a tool to increase heat recovery and e ciency of energy usage. Heat

exchangers must comply to the requirements for the minimal temperature dif-

ferences. This conditions can be satis

ed by a plate heat exchanger, hereinafter

referred to as PHE (Arsenyeva et al., 2011). PHEs are, at this moment, the most e cient types of heat transfer equip-

ment. It requires less material for heat transfer surface production, as it is

more compact than the conventional heat exchangers. Because of this, it has

a smaller footprint than typical shell and tubes units. The main advantages of

PHEs are the compactness, low total cost, less fouling,

exibility in changing the

heat transfer surface area and accessibility. Flexibility represents the structural

characteristic of the PHEs, as the heat transfer surface area can be changed

easily. This is done by adding a step equal to heat transfer area of one plate.

To assure that PHEs comply to the required heat loads and pressure losses, the

manufacturers produce plates with di erent sizes, heat transfer surface areas

and geometrical forms corrugations (Arsenyeva et al., 2011). The most important property of PHE design is the fact that the conditions

implemented for the heat transfer process can be complied with by using a num-

ber of di erent plates. When selecting the most suitable plate, the optimization

criterion is taken into consideration. Consequently, to design an optimal PHE,

taking into consideration the process conditions, a wise selection for the best

option, from available alternative options of plates with di erent geometrical

characteristics, must be made. A mathematical model is used to make the right

decision, by estimating the performance of the di erent alternative options.

This should be accurate enough with small numbers of parameters that can be

identi

ed on a data available for commercial plates (Arsenyeva et al., 2011).An

example of streams

ows through channels in multi-pass PHE is shown in

g. 5. Figure 5: An example of streams

ows through channels in multi-pass PHE

(Arsenyeva et al., 2011)

Air-to-air heat exchanger

Heat exchangers are used in ventilation systems which are installed in resi-

dential, commercial and industrial buildings to eliminate heat or moisture to a

second air stream (Chagnot, 1991). An air-to-air heat exchanger is a ventilation

system that transfers the heat of the exhausted stale air to the inbound fresh

and cold air. This process is maintaining the heating cost within reasonable

limits. The air-to-air heat exchangers are complex hardware and consequently

costly to manufacture (Courchesne, 1987). Air-to-air heat/energy recovery ventilators are very popular for heating, ven-

tilation and air-conditioning purposes. These ventilators are necessary in these

systems in order to reduce the energy consumption for ventilation and the green-

house air emissions, particularly in hot and humid or cold climates. In these

systems, the fresh air coming from outside and the indoor stale air enter the

heat exchanger though two separated sides. Sensible heat, latent heat or both

are transferred from one air stream to the other. This process depends on the

temperature and moisture gradients.When warm and humid exhaust air passes

over the surface of the cold plate of an exchanger, water vapor condenses and

frost is formed on the surface if the plate temperature is lower than the dew

point of the air and the freezing point of the water. In cold climates zones,

such as Canada and northern Europe, frost often forms in the device during

the winter and it can a ect the productivity of heat exchangers. This frosting

problem is especially important when the outdoor temperature is very low (Liu

et al., 2016).

Bibliography

Arsenyeva, O. P., Tovazhnyansky, L. L., Kapustenko, P. O., and Khavin, G. L. (2011). Optimal design of plate-and-frame heat exchangers for e cient heat

recovery in process industries. Energy, 36(8):4588{4598.

Breeze, P. (2016). Gas-turbine power generation . Academic Press.

Chagnot, B. J. (1991). Air to air recouperator. US Patent 5,069,272.

Courchesne, G. (1987). Air-to-air heat exchanger. US Patent 4,653,575.

Day, J. (1980). Engines: the search for power . St. Martin’s Press.

Giampaolo, T. (2006). Gas turbine handbook: principles and practice . Fairmont

Press.

Kurzke, J. and Halliwell, I. (2018). Propulsion and Power: An Exploration of

Gas Turbine Performance Modeling . Springer.

Lefebvre, A. H. (1998). Gas turbine combustion. CRC press.

Liu, P., Nasr, M. R., Ge, G., Alonso, M. J., Mathisen, H. M., Fathieh, F., and Simonson, C. (2016). A theoretical model to predict frosting limits in cross-

ow air-to-air

at plate heat/energy exchangers. Energy and Buildings,

110:404{414.

Schobeiri, M. T. (2017). Gas Turbine Design, Components and System Design

Integration . Springer.

Shah, R. K. and Sekulic, D. P. (2003). Fundamentals of heat exchanger design.

John Wiley & Sons.

Usher, A. P. (1988). A history of mechanical inventions. 1929. P. 155Usher155A

History of Mechanical Inventions1929 .