The WR-21 for Cruise Ships?
Matching the Attributes of the
WR-21 Intercooled Recuperated Gas Turbine
to the Propulsion and Domestic Requirements
of a Large Cruiseliner
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The WR21 for cruise ships ?
Matching the attributes of the WR21 intercooled
recuperated gas turbine to the propulsion and domestic
requirements of a large cruiseliner
Name: M.W.P. van Lier
Professor: Prof. ir. J.P. van Buijtenen
Mentor: ir. C.J. Houtman
R.W. Tooke (Rolls Royce)
Assignment: EV-418
Preface
Dear reader,
Before you get notice of anything in this report I would like you to know that this
thesis could never have been established without the help of some people. Each of
them have contributed in their own special way and I would like to thank them fir that
very much.
Anoek, my girlfriend, who I left behind in the Netherlands for
a considerable period
and who has supported me the whole way through. Thanks, Anoek. I know you also enjoyed your short visits to England.
Roger, fir your guidance and support at Rolls Royce and fir the wonderful time I had
living with your family, Judy, Alex, Gregory and Kathy. I will never forget your hospitality. By the way, Judy thanks for letting me drive in your car.
Gordon, thanks for your patience, from now on your computer will only he yours. Tim, you have always had the patience to provide me with the right information or
pointed me in the right direction. Thanks fir that. Albert, thanks for your concern and
critical remarks, they were all very useful.
More generally I would like to thank the people of Rolls Royce that have helped me in any way possible, always friendly and the people outside Rolls Royce that have
provided me with all the information I needed for this report, Simon Yeo of Princess
Cruises, thanks Simon, Jeff Buckley of Cegelec Projects, Richard Railing ofSenior
Thermal Engineering, Laurent Mazodier and Etienne Martinache ofCegelec DEI
BelfOrt and Roger Mudge of the Ministry of Defence
Finally I have to thank the people of the Royal Netherlands Navy and Rolls Royce that gave me this exceptional opportunity to do this MSc-project. Thank you all.
Summary
While having studied ship propulsion systems and the current practise in cruise ship
machinery design simultaneously it has been recognised that there have been two distinctive changes in cruise ship design since 1980. First the size of the ships has increased from average 40,000 [ton] gross tonnage to a design of 105,000 [ton] gross tonnage in 1997. The second change is the fact that the conventional diesel mechanical propulsion system has been replaced almost entirely by diesel electric propulsion systems. Up till now no cruiseship has been designed with gas turbines as a prime mover.
This will be explained in the first chapter before it is actually tried to create a cruise ship operating profile combined with the total energy demand of the ship, which consists of the shaft power demand, the auxiliary power demand and the heat demand. This is all based on the provided information on a 77,000 [ton] GRT cruise ship, used as a typical ship.
Before it can actually be judged whether theWR2 Ii intercooled and recuperated gas turbine is capable of meeting the total energy demand it should be examined what the performance of the WR21 will be if it is applied on a cruise ship. Both the ambient conditions and the pressure losses in the intake and exhaust have an influence on the performance of the WR21. Those conditions and pressure losses will be determined for a typical cruise liner application and as a result we will know the WR21 performance.
In the second chapter it is then possible to match the WR21 engine attributes with the typical cruise liner requirements by composing several machinery configurations where WR21 gas turbines are used as prime movers. The following configurations options are made:
WR21 gas turbine electric configuration
WR21 gas turbine electric configuration with waste heat recovery boilers WR21 gas turbine electric configuration with an additional diesel engine
WR21 gas turbine electric configuration with waste heat boilers and an additional diesel engine
The machinery configurations without waste heat recovery boilers will have a separate steam boiler system to provide in the heat demand. A similar oil fired boiler system will be applied in the configurations with waste heat boilers for the cases that the waste heat boilers can not meet the demand.
The third chapter then deals with the comparison of those four configurations. The options will be compared using the following comparison criteria:
Unit Purchase Costs
Through Life Costs Fuel type and Fuel Consumption Costs Maintainability and Maintenance Costs Dimensions and ship fit implications
Reliability, Availability and Redundancy Emissions
Relevant legislation
Each criterion is constructed in such a way that it is possible to quantify the attribute and use it to compare the four options. The comparison has to lead to the conclusion which
comparison, leads to a different conclusion. If a machinery configuration is chosen.
concessions will have to made. A redundant system could imply a system with high emission levels or an expensive system.
The last chapter is in fact a side step from the study on meeting the total energy demand of a 77,000 [ton] GRT ship. It is tried to create a model that will make it possible to predict the total energy demand of a cruise ship of any size. This model is based on the information provided for the 77,000 [ton] ship.
It is for the model assumed that the non-dimensional ship resistance coefficients and the open water efficiency of the typical cruise ship are similar to the coefficients and efficiencyof other cruise ships. It is further assumed that there is an average amount of passengers per ton gross tonnage and that the passengers require an average amount of auxiliary power and heat. This model leads to the conclusion that a mechanically driven ship is only suitable for a WR2 I configuration in a very specific case considering size or speed. The reason for this is the fact that a twin screw cruise ship requires a WR2 I gas turbine on each shaft. The cruise liner then also still requires a high auxiliary load to be met by a power station. With an electrically propelled ship the combination can be made with the required shaft power and the auxiliary power, the domestic load.
The overall conclusion finally is that the WR2 I is certainly applicable on a cruise ship. It is however necessary to compare a WR2 I gas turbine electric configuration with the currently used diesel electric configurations. This will help to recognise whether the cruise ship
industry can be triggered to use a gas turbine electric configuration instead of a diesel electric one. Only then a further investment in the WR2 I application is justified.
Samenvatting
Het tegelijkertijd bestuderen van voorstuwingssytemen voor schepen algetneen en de
maritiem werktuigkundige systemen aan boord van cruise schepen heeft geleid tot de conclusie dater sinds 1980 twee duidelijke veranderingen hebben plaatsgevonden in het
scheepsontwerp van cruise schepen. Ten eerste is de omvang van de schepen gestegen van
een gemiddelde 40.000 [ton] tot een ontwerp in 1997 van 105.000 [ton]. Deze waarden
hebben betrekking op de 'gross tonnage', de algemeen gebruikte grootheid voor dir soon schepen.
De tweede verandering is bet felt dat Ihet conventionele diesel mechanische voortstuwings
systeem bijna in alle gevallen is vervangen door een diesel electrisch systeem.. Tot nu toeis nog geen enkel cruise schi,p uitgerust met gasturbines als hooldaandruver.
flit wordt behandeld in het eerste hooldstuk voordat er een begin wordt gemaakt met het feitelijke samenstellen van een vaarprofiel voor een cruise whip gecombineerd met de totale
lenergie behoefte van het schip, hetgeen bestaat nit het gevraagde asvermogen, hulpvertnogen
en de warmtebehoefte. Dit is allemaal gebasseerd opde verkregen informatie van een
specifiek cruise schip van 77.000 [ion] GRT..
'Voordat feitelijk kan worden beoordeeld of de 'intercooled' en 'recuperated' WR2
gasturbine daadwerkelijk in staat is om in de energie behoefte te voorzien, moct eerst worden
onderzocht wat de prestatie of de WR2I is als deze wordt toegepast op een cruise schip.
Zowel de omgevingsdruk en -temperatuur en de drukverliezen in de in- en uitlaat hebben een invloed op de prestaties van de machine. Deze omgevingscondities en drukverliezen zullen worden bepaald voor de WR2I applicatie op het specifieke cruise schip met als resultaat de
prestaties van de WR21 gas turbine.
in het tweede hoofdstuk is het vervolgens mogellijk om de kentnerken van de WR2 I gas
turbine aan te passen aan de voortstuwings en platform behoeften van het voorbeeld schip
door verscheidene systeem conliguraties samen te stellen waarin WR2I gasturbines als hoofdaandrijvers worden gebruilst. De volgende configuratie optics worden gemaakt:
WR2 I gasturbine electrische configuratie
WR21 gasturbine electrische configuratie met afvalwarmte benutting
; WR2 I gasturbine electrische configuratie met een additionele dieselmotor
WR2 I gasturbine electrische configuratie met zoweli afvalwarmte benutting als
een additionele gas turbine
De machine systemen zonder afvalwarmte ketels zulren een gescheiclen stoomketel systeem
hebben om in de warmtebehoefte te voorzien. Een zelfde brandstof gestookt ketel system zal worden gebruikt om het tekort in warmte aan; te vullen in het gevall van de configuraties met afvalwarmte ketels.
Het derde hoofdstuk ,behandelt vervolgens de vergelijking van deze vier configuraties. De opties zullen worden vergeleken met !bet volgende vergelijkingscriteria:
Aanschafsprijs
Levenscycllus kosten Bramistoftype en brandstof consumptie Roster/
- Betrouwbaarhe id, Beschikbaarheid en Redundantie
- Emissies
- Relevante wetgeving
Elk criterium wordt op zodanige wijze gedefinieerd dat her mogelijk is om het kenmerk te quantificeren en te gebruiken om de vier optics te vergelijken. De vergelijking zou moeten leiden tot de conclusie welke configuratie de beste oplossing geeft. I let blijkt echter dat elk criterium, dat gebruikt kan worden, leidt tot een andere conclusie. Er zullen dus concessies gedaan moeten worden indien een machine system gekozen wordt. Een redundant systeem
kan betekenen dat het systeetn een hoog etnissie niveau heeft of dat het systeem duur is in kosten.
Het laatste hoofdstuk is in feite een zijstap van de studie naar het voorzien in de behoefte van
een 77.000 [ton] cruise schip. Er wordt getracht om een model te vormen van dat het mogelijk maakt om om the complete energie behoefte te voorspellen van een cruise schip van elke gewenste omvang.. flit model wordt gemaakt met de gegevens van het 77.000 [ton] GRT cruise schip.
Voor het model wordt aangenomen dat de dimensieloze scheepsweerstand coefficienten en
het open water rendement van bet voorbeeld schip gelijk zijn aan de coefficienten en
rendementen van andere cruise schepen. Verder wordt aangenomen dater een gemiddeld aantal passagiers per ton 'gross tonnage' bestaat en dat er een gem iddelde behoefte is naar hulpvermogen en warmte per passagier.
Dit model leidt tot de conclusie dat een mechanisch gedreven schip alleen van toepassing is
voor een WR21 configuratie in een specifiek geval met betrekking tot omvang en maximale
snelheid. De reden hiervoor is het feit dat een dubbelschroefs cruise schip een WR21
gasturbine verlangt aan elke as. Het cruise schip heeft daarnaast nog altijd een hoge behoefte
aan hulpvermogen, waarin moet worden voorzien door een ander vermogensbron. Bij een
electrisch gedreven schip kan er gecombineerd worden met her gevraagde asvermogen en het hulpvermogen.
De algemene conclusie is tenslotte dat de WR21 zeker toepasbaar is op een cruise schip. Het
is echter noodzakelijk om de WR21 gasturbine electrische configuratie te vergelijken met de huidige diesel electrische configuraties. flit zal helper) om te kijken of de cruise industrie kan worden overgehaald om een gasturbine electrische configuratie te gebruiken in plaats van een diesel electrische. Aileen clan kan een verdere investering in de WR2 I applicatie worden
Contents
Introduction
11. The cruise liner requirements and the attributes of the
WR21
2
I .1 A review of propulsion systems 3
1.2 Trends in cruise liner requirements 6
1.3 Total energy profile of a typical cruise ship 8
1.3.1 The operating profile of the ship 8
1.3.2 Combining the operating profile and the shaft power demand 10 1.3.3 The electric load balance
1.3.4 Steam load balance 12
I .4 The WR21 intercooled and recuperated gas 14
1.5 WR21 Performance on a cruise ship 15
1.5.1 The ambient pressure and ambient temperature IS
1.5.2 Intake and exhaust losses 16
1.5.3 The output of the WR2 I on a cruise ship 22
Cruise ship machinery configurations with the WR21 ....25
2.1 Option 1: The gas turbine electric configuration 16
2.1.1 Selection of a suitable generator for the WR2 II 26
2.1.2 Selection of a propulsion system 18
2.1.3 Losses in the propulsion system 30
2.1.4 The steam production 32
2.2 Option 2: The gas turbine electric configuration with waste heat boilers 33
2.2.1 Selection of a suitable Waste Heat Recovery Boiler for the WR2 I 33
2.3 Option 3: The WR21 gas turbine electric configuration with an additional prime
mover 36
2.3.1 Selection of a suitable prime mover to be used besides WR2 1 gas turbines 36
2.4 Option 4: The WR2 1 gas turbine electric configuration with WHB and additional
prime mover 39
Comparison of the configurations
40
3.1 Unit Purchase Costs 41
3.1.1 Option I: The gas turbine electric configuration 41 3.1.2 Option 2: The gas turbine electric configuration with waste additional waste
heat boilers 45
3.1.3 Option 3: The WR2 1 gas turbine electric configuration with an additional prime
mover 45
3.1.4 Option 4: The WR21 gas turbine electric configuration with an additional prime
mover and waste heat recovery boilers 47
3.2 Type of fuel and annual Fuel Consumption Costs 48
3.2.1 Choice of the right type of fuel 48
3.2.2 Annual fuel consumption costs 49
3.3 Maintainability and Maintenance Costs 50
3.3.1 Quantitative comparison in maintenance costs for different operating hours of
the WR21 51
3.3.2 Qualitative comparison of the options 53
3.4 Through Life Costs 55
3.5 Dimensions and ship fit implications 57
3.6 Reliability, Availability and Redundancy 61
3.7 Structure born and air born noise levels 63
3.8 Emissions 64
3.9 Relevant legislation 68
3.10 Conclusions 70
Generalisation of cruise ship requirements
72
4.1 Matching a cube law curve to sea trial results of the Sun Princess 73 4.2 The non-dimensional resistance coefficient 75
4.3 Interaction of hull and propeller 78
4.4 The resistance and hull and propeller interaction of the Sun Princess
4.5 The generalised total energy demand of cruise ships 88
4.6 Validation of the model 90
4.6.1 The model of a 70,000 GRT ship 91
4.6.2 The model of a 100,000 GRT ship 93
4.6.3 The maximum required power related to the gross tonnage and maximum
speed
Conclusions
96
Recommendations
98
References.
Nomenclature and Symbols
103
Separate issue:
Appendix (contains all Annex references)
.
.
41..
... . . .
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Introduction
In December 1991 the US Navy awarded the contract that would mean the start of the design and development of a new type of gas turbine, the WR21. New features of this gas turbine compared to conventional simple cycle gas turbines are the intercooler, the recuperator and power turbine variable area nozzles. As a team member in the WR2 I-project, Rolls Royce Industrial and Marine Gas Turbines Ltd. is responsible for the development of the gas
generator and power turbine.
The WR21 will become the next prime mover on the US Navy new construction surface combatant ships. Both the US Navy and Rolls Royce are looking at the application of the WR2I outside the naval industry. A commercial marine operation of the WR21 would mean more production engines and consequently lower unit production costs and a better service support infrastructure.
This is the reason why Rolls Royce has asked to look into the possibilities of applying WR2 I engines on cruise ships. The cruise ship industry is recognised as a potential industry where the WR21 could be applied as a prime mover. For that reason Rolls Royce would like to
understand the market. This has resulted in an assignment for a study as can be found in
Annex A.
The objective of the study will be matching the attributes of the WR21 gas turbine to the propulsion and domestic requirements of a large cruise liner. The prerequisites to meet this objective are understanding the cruise ship industry and becoming familiar with the WR21
engine.
The study will conclude on the question whether further investment in WR21 application for a large cruise liner is justified and whether modification of the WR21 lay-out could lead to better fulfilment of the ship requirements.
1. The cruise liner requirements and
the attributes of the WR21
The US Navy contract was awarded to Westinghouse Marine Division for the design and development of an intercooled and recuperated gas turbine system, the so called WR21. Westinghouse was the prime contractor at that time and responsible for the system
integration. However recently the Westinghouse Marine Division has changed into Northrop Grumman Marine systems (NGMS) and the latter has taken over the responsibilities as the prime contractor.
The complete team that has been carrying out the design consists besides NGMS of Rolls Royce, who are responsible for the gas turbine design and development, Allied Signal, who are responsible for the intercooler and recuperator design and development and CAE Electronics, who are responsible for the control system development. Besides the naval application of the WR2 I, the project would also like to know what the possibilities are of a commercial marine application, e.g. on cruise ships.
The cruise ship industry is still able to exist and expand because an increasing number of people are willing to spend their money on a cruise holiday. The obvious function of a cruise ship is to transport people to prescribed locations in the most comfortable manner possible. The limitations imposed on comfort by being onboard a ship have to be minimised. An additional requirement of the cruise ship machinery is therefore to have minimum
interference with the passengers comfort. It is assumed that the reader is acquainted with ship machinery configurations in general.
Like is said in the introduction, this project's aim is looking at the possibilities of applying WR2I engines to large cruise liners. The WR21 is a gas turbine rated at 25.2 [MW] and therefore a relatively high power prime mover. This makes the WR21 first of all suitable for being applied as a prime mover in the propulsion package of ships. The next section will give a review of propulsion system for ships in general and after that it will be made clear what the requirements are of a large cruise liner and what the performance is of the WR21 applied on a cruise ship.
If the WR21 is applied on a cruise ship we have to assume certain ambient conditions which have their influence on the performance of the WR21. In this chapter the ambient conditions for a cruise ship with its operating area in the Caribbean and Alaska will be determined. Another point are the intakes and uptakes of the WR21 gas turbine on cruise ships. This design will be somewhat different from the designs in naval applications and also the
pressure losses in both those systems have a certain influence on the performance of the engines. Hence also the intakes and uptakes need to be determined before the actual WR21
1.1 A review of propulsion systems
The WR2I intercooled and recuperated gas turbine is an engine rated at 25.2 [MW1 at ISO (no loss) conditions. Because of this high power rating the WR21 is suitable to be applied in the propulsion system of ships. The definition of a propulsion system is: The system which provides the power that the ship needs to move with a required speed. In order to stay at the required speed the force that provides the ship with thrust has to equal the total resistance of the ship at that speed. This will be discussed more in detail in Chapter 4. In order to
accelerate the thrust has to be larger than the resistance force.
Commonly a propulsion system consists of three basic elements. Those elements are the
prime mover, the transmission and the propulsor. This is illustrated in Figure 1.1. It is optional that a part or the complete auxiliary power of the ship is also provided by the same prime mover which drives the propulsor. This could be the case for electric propulsion or for
instance with shaft generators.
PRIME
MOVER TRANSMISSION PROPULSOR
AUXILIARY
POWER
Figure LI:, Basic elements of a propulsion system
The function of a prime mover is to deliver mechanical energy, and it is able to do so
releasing fuel energy. Almost all of the prime movers in the ships of today are diesel engines. Another prime mover is the gas turbine, used for example at the frigates of the British Royal Navy and the Royal Netherlands Navy. Further it is also possible to use a steam boiler with
steam turbines as prime movers instead of a gas turbine or a diesel engine. The steam
production methods include oil fired boilers, nuclear reactor (as in a nuclear submarine), or gas (-product) fired boilers.
The function of the transmission system is to transfer the given mechanical energy of the prime mover to the propulsor with the characteristics that are required by the propulsor. Another function of the transmission system is to transfer the reaction force, caused by the interaction between prime mover and propulsor, to the ship. This is done by a component called the thrustblock. Finally it could be possible that the transmission system also transfers the mechanical energy of the prime mover into electrical auxiliary' energy. This has to be
done via an alternator.
Direct transmission: The prime mover is directly coupled to a propeller by a shaft. Indirect transmission: A gearbox is placed between the prime mover and the propulsor shaft to reduce the rotational speed of the prime mover to an acceptable speed for the propulsor. At the same time the gearbox increases the torque in the same relative amount as the decrease in rotational speed. The advantage of this is that the prime mover is able to work at a higher rotational speed and in that way it can be smaller, lighter and cheaper in comparison with a direct transmission. A non-mechanical transmission: This could be an electrical transmission system.
In that case the prime mover will drive an alternator. The alternator will supply an electrical distribution system with electric power through a converter system to drive an electrical propulsion motor which drives on its turn the shaft with propeller. The transmission system consists in that case of the alternator, cabling, converter, propulsion motor and shaft. The electrical distribution system will also provide the auxiliary power. Further a ship with a pumpjet propulsion system also requires a non-mechanical transmission system. In that case the prime mover drives a pump, directly, with an interconnected gearbox or electrically. The pumpjet system accelerates the water which leaves the ship at the stern. In that way the system is able to thrust the ship.
As will be discussed later, most of the recent built cruise ships and the cruise ships that will be built in the future are provided with a diesel electric propulsion system. Because of that it has been decided to pay special attention to the electrical transmission systems, including the electric motors and the power electronics. The information is given in Annex 1.A. It is a global review of the possible elements in such a propulsion system. For more detailed information I would like to refer to the corresponding literature on the specific subjects. The function of the propulsor is to transfer the transmitted power into a thrust power to move the ship in the required direction. Most of the time one uses a propeller for this but one can use other types of propulsors. Those could be for instance the already discussed pumpjet or the so-called Voith-Schneider propulsion system with cycloidal propellers. The second consists of vertical blades that are rotating around a vertical axis. By changing the relative angle of the vertical blades, the ship can be manoeuvred in every direction.
There are also different types of propellers. The distinction that is made in this study is between the fixed pitch propeller, the controllable pitch propeller and an azimuthing thruster as main propulsor. The implications of applying a fixed or a controllable pitch propeller are discussed in Annex 1.B.
In October 1995 Carnival Cruise Lines ordered a modification to their last two Fantasy-class ships, the Elation and the Paradise, as can be seen in Table 1.1, ready for delivery in 1998. The two vessels will be equipped with two 14 MW pulling Azipods, a special type of azimuthing thruster, of the Kvaerner MASA yards in Finland.
The definition of an azimuthing thruster is an electric motor located inside a pod directly driven by a fixed or controllable pitch propeller and azimuthing through 3600. The Azipod is positioned in place of the rudder. An example is given in Figure 1.2. According to the definitions used so far for transmission system and propulsor, the Azipod is not only a propulsor but also partly the transmission system.
ships electric power supply system. Because the pod is azimuthing there has to be a power data transfer from the rotating part to the non-rotating part. This happens via sliprings or flexible cables. The inside of the rotating part which contains the electric motor, bearings and shaft seals, needs cooling. An air cooling system provides the cooling air to the motor.
Hydraulic Steering
Unrt-Installation Block
Bearing, Shaft Seals
I Slipring Unit (Power/Data transmission)
Ventilation Unit
Searing
Air cooling
Figure 1.2: Azipod principle
Shaft Line Electric Motor
FP propeller
-1.2 Trends in cruise liner requirements
Before looking at the possibilities of applying a WR21 into a large cruise liner, we have to know what the current practise is in the designs of those ships. So far no cruise yard has built a passenger cruise ship with a gas turbine as main engine. The main cause for this could be the fuel economy. Even at the moment the higher fuel costs of marine gas oil compared to the price of heavy fuel oil, does not encourage for opting gas turbines.
So up to now the cruise liner market has made use of medium-speed and slow-speed engines as prime movers. The type of transmission that has been used for the slow-speed engines has been a direct drive and for the medium-speed diesel engines an indirect mechanical drive has been used the most. But recently there has been an increase in the use of diesel electric propulsion systems. In fact only a few of all the recent built ships or the ships that will be built in the near future are provided with a diesel mechanical propulsion system. Those ships are the Oriana of Princess Cruises, and the three Century-class ships, the Century, Galaxy and the Constellation of Celebrity Cruises.
The reason why the Oriana is provided with a geared propulsion system is the fact that the Oriana was built in Germany, at the 'Meyer Werfe, at that time not familiar with
constructing electrically driven ships.
In 1994 even the use of an diesel electric concept predominated as the preferred propulsion source. The first thing to explain is why does the cruise liner industry choose for the
combination of a diesel engine as prime mover and an electric drive as transmission. A lot of advantages of diesel-electric propulsion are mentioned in many papers whilst comparing it with the traditional diesel mechanical drive. The reason why especially cruise liners are suitable for using electric propulsion systems is the fact that particularly cruise ships have a high electric power demand for domestic services, such as refrigerating, air conditioning and lighting. Most of the time the total energy distribution could be about 40 per cent for the hotel services and 60 per cent for propulsion power. So in any case a cruise ship requires a big power station to meet the high electric power demand even without electric propulsion. But also a low noise level is an advantage of the electric propulsion system that benefits for a cruise ship, because it is better for the passengers comfort. And a diesel-electric propulsion system could save engine room space. However this is low grade space more passenger cabins could theoretically be fitted into the same hull.
The advantages that are mentioned, are of course also dependent on the background of the one who describes them. But the facts are that all these advantages are more or less true and that most of the cruise ships, in present or future, have a diesel-electric propulsion system.
Most of the diesel electric ships are mentioned in Table 1.1.
Except from the trend that diesel electric systems are applied instead of diesel mechanical, two other trends have been recognised while trying to understand the cruise ship industry. For the scope of this project most of the interest lies in the larger and recently built ships or the ships that are under construction at the moment. It has been recognised that since 1980 the size of cruise ships has changed from an average 40,000 [ton] gross tonnage to an average
The other trend is the fact that cruise ship operators want to expand the operation area of their cruise ships. The Oriana is meant to cruise in Europe, the Caribbean and even to cruise world wide. This implies that the ships have to become faster in order to reduce the transit
times.
Table 1.1: Cruiseliners with a diesel-electric propulsion system made in past and future, source
Operator/owner Name Power inst. GRT Builder
yr
Built Ships
P&O Cruises Star Princess 39000 kW 63524 Alsthom Atlant. 89
Carnival Cruise Lines Fantasy 42240 kW 70367 Kvaerner MASA 90
Carnival Cruise Lines Ecstacy 42420 kW 70367 Kvaerner MASA 91 Holland America Line Statendam 34560 kW 55451 Fincantieri 92
Holland America Line Maasdam 34560 kW 55451 Fincantieri 93
Holland America Line Rijndam 34560 kW 55451 Fincantieri 94
Carnival Cruise Lines Fascination 42240 kW 70367 Kvaerner MASA 94
Holland America Line Veendam 34560 kW 55451 Fincantieri 95
Carnival Cruise Lines Imagination 42240 kW 70367 Kvaerner MASA 95
N.Y.K, Line Crystal Symphony 38880 kW 50000 Kvaerner MASA 95
Royal Caribbean Cl... Legend of the Seas 54300 kW 70000 Chant. Atlantique 96
Carnival Cruise Lines Inspiration 42240 kW 70367 Kvaerner MASA 96
P&O Cruises Sun Princess 46080 kW 77000 Fincantieri 96
Carnival Cruise Lines Carnival Destiny 63400 kW 100000 Fineantieri 96
Royal Caribbean C.L. Splendour of the Seas 54300 kW 70000 Chant. Atlantique 96
Royal Caribbean C.L. Grandeur of the Seas 54300 kW 73000 Kvaerner MASA 96
Costa Crociere Costa Victoria 50700 kW 75200 Bremer Vulkan 96
Future Ships
P&O Cruises Dawn Princess 46080 kW 77000 Fincantieri 97
Royal Caribbean C.L. Enchantm. of the Seas 54300 kW 73000 Kvaerner MASA 97
1)&0 Cruises Grand Princess 69120 kW 105000 Fineantieri 97
Royal Caribbean C.L. Rhapsody of the Seas 50400 kW 70000 Chant. Atlantique 97
Carnival Cruise Lines Elation 47250 kW 70367 Kvaerner MASA 98
Carnival Cruise Lines Paradise 47250 kW 70367 Kvaerner MASA 98
Carnival Cruise Lines Carnival Triumph 63400 kW 101000 Fincantieri 98
Royal Caribbean C.L. Vision of the Seas 50400 kW 73000 Chant. Atlantique 98
Costa Crociere Costa Olympia 50700 kW 78000 Bremer Vulkan 98
Disney Cruise Lines Disney Magic 57663 kW 85000 Fincantieri 98
Disney Cruise Lines Disney Wonder 57663 kW 85000 Fincantieri 98
1)&0 Cruises Sea Princess 46080 kW 77000 Fincantieri 99
I'
-1.3 Total energy profile of a typical cruise ship
The information used to create a general cruise ship profile information was provided by Peninsular & Oriental Steamship Co.'s (P&O) Princess Cruises. To most cruise ship operators the Caribbean remains the favourite operation area for the growing European
market. The part of Princess Cruises' fleet that is operating in the Caribbean area is also operating in Alaska for a certain period per year. The ships involved are the Royal Princess,
built in 1984, the Star Princess, built in 1989, the Crown Princess, built in 1990, the Regal Princess, built in 1991, the Sun Princess, built in 1995. In May 1997 the Dawn Princess will join the fleet which has their home base in Fort Lauderdale, Florida. The part of the fleet that replies to the scope of this study is shown in Table 1.2.
Table 1.2: Fleet information PrincessCruises
The Sun Princess-class ships, the Sun Princess, Dawn Princess and Sea Princess, are or will be provided with four 11,128 kW generator-sets, driven by Sulzer 16ZAV4OS diesel engines of 11,520 kW MCR. The Grand Princess will have six engines of the same type.
The Oriana's mechanical propulsion system consists of two 11,925 kW and two 7,950 kW four stroke diesel engines of the type MAN B&W L58/64, respectively with nine and six cylinders. Both shafts of the Oriana are provided with a 5,250 kVA shaft generator and it has four auxiliary diesel-generator sets of the same power.
The information that Princess Cruises has provided is based on their latest operational ship in the Caribbean, the diesel-electric Sun Princess. Because of the fact that no information could be obtained on other ships, it is clear that the typical cruise ship profile that will be used is a profile very similar to that of the Sun Princess. In Chapter 4, a model will be created capable of predicting the total energy demand of a more generic cruise ship.
Three steps will be used to create the profile of the typical cruise ship. Those steps are based on gaining knowledge of the operating profile of the ship, the electrical power demand and heat demand
1.3.1 The operating profile of the ship
Cruise ship operators have their ships operating in a certain area and they plan the cruise itineraries a long time ahead. A Princess Cruises brochure from a travel agents shows that the American based vessels spend their time from October until April in the Caribbean and the rest of the time in Alaska. This is what has been used to create the operating profile, as suggested by the spokesman of Princess Cruises.
Typical cruise itineraries are provided by Princess Cruises with time tables and speeds. This
Name Prop.
System Year
CRT
(tonnes) Yard Operation area
Sun Princess DE 1995 77000 Fincantieri Carib./Alaska
Dawn Princess DE 1997 77000 Fincantieri Carib./Alaska
Sea Princess DE 1999 77000 Fincantieri Carib./Alaska
Grand Princess DE 1997 105000 Fincantieri Caribbean
Oriana DM 1995 69153 Meyer Warft Med./Carib./ World Wide I
Table 1.3: Itinerary information of Princess Cruises
period that every speed is used. The itineraries Ill, IT2 and IT3 are 7 day cruises in the Caribbean, IT 4 is an II day cruise in the Caribbean and ITS is a 7 day cruise in Alaska. Comparing the tables of Princess Cruises to the brochure from the travel agent's shows that itinerary ITI is the cruise itinerary that the Star Princess sails and itinerary IT3 belongs to the Sun Princess. The 11 day cruise is a typical cruise for the fleet as a transit through the
Panama Canal to Acapulco and after that, the ships will start their period in Alaska with cruises like ITS.
It has been announced that the Sun Princess would be used as an example because the total
energy demand in the provided information is based on the Sun Princess. However, it would not be right to use only the itineraries IT3, IT4 and ITS from Table 1.3. This is because the
speeds mentioned in the tables from Princess Cruises are average speeds and, though the Sun
Princess is the basis for the typical profile, it is not necessary to use only the information of that cruise ship. Therefore it is arbitrarily assumed that all three cruises in the Caribbean, IT1, IT2 and IT3, are representative for the operating profile. Again, this is a generalisation but will be used as if it were the basis for a new cruise ship design. The conclusion from this is that during the period in the Caribbean one third of the total time is used for each itinerary.
In Annex IC it is shown how a typical profile is created with the information of Table LI
This has resulted in the profile as shown in Figure 1.3. The values are mentioned in Table
CARIBBEAN IT1 7 d. Speed (knots) Period (hrs.) IT2 7
d
' Speed (knots) Period (hrs.) IT3 7 d Speed (knots) Period (hrs.) 20.5 94.0 18.3 12.0 19.1 15.0 18.0 0.5 16.2 30.0 18.2 18.0 15.2 11.5 13.2 11.0 15.1 85.5 3.3 12.0 , 12.9 12.0 man. 9.5 man. 8.5 10.8 11.0 in port 40.0 in port 41.5 8.4 10.5 X X X X man. 11.5 X X X X in port 70.0 X X CARIBBEAN ALASKA IT4Ii
d
Speed (knots) Period (hrs.) ITS 7 d , Speed (knots) Period (hrs.) 20.4 37.0 19.8 24.0 19.6 14.0 17.5 15.5 19.2 12.0 15.9 35.5 19.1 15.0 ' 15.3 9.0 18.5 60.0 12.2 9.0 14.3 12.0 I 7.9 12.0 1.1 18.0 man. 9.5 man. 14.5 in port 53.5 in port 81.5 X X , IFigure 1.3: Simplified cruise ship profile
Table 1.4: Values of simplified cruise ship profile
1.3.2 Combining the operating profile and the shaft power
demand
If the operating profile is combined with the shaft power demand it is possible to create a shaft power demand profile. This enables us to predict the power demand of the propulsion system in time. The efficiencies in the propulsion system then define the power demand of the prime mover in the end. The way the shaft power demand is dealt with is fully described in Chapter 4 and I would like to refer to that section regarding the combination of shaft
power to ship speed. The whole profile can then be summarised, which has been done in
Table 1.5, and is illustrated in Figure 1.4.
Cruise ship profile
30
-25A
20lik
Va :. 15IL
.r
E at 10A
1.4
5 a 1 0 0 10 20 30 40 50 ea 70 80 90 ioU Paled %mod 1%1Speed levels [knots] Rated speed [Vol % Time at sea
22.6 100 18.0 18.5 81.9 6.6 15 66.4 29.3 8 35.4 6.0
/
8.9 1.6 61.5Rated speed [/o] Actual speed [knots] Required shaft power [kW] `)//0 Time at sea
100 22.6 28000 18.0 81.9 18.5 14800 6.6 66,4 15.0 7000 29.3 35.4 8.0 829 6.0 8.9 2.0 15 1.6 61.5 H I I
30000.0 25000 0 20000.0 M 15000 0 Ow 10000 0 5000 0 0.0
Shaft power profile of cruise ship
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Figure 1.4: The propulsion profile of the typical cruise ship
1.3.3 The electric load balance
The main task of a electrical ship service system is to make sure that at every moment in time all consumers have their required active and reactive electrical power. To fulfil this task, the system has to generate enough power and distribute it correctly. In the scope of this project the distribution will be taken as a fact and we will only focus on the generation of the electrical power.
The auxiliary power is often referred to as the hotel load or the domestic services load. In order to define the (maximum) load demand, we are going to use an electrical load balance. In a ship design load balance we have to incorporate every electric device on board. Having the list with all the devices the load balance consists of the load demand of every device in several operating levels. Those operating levels could be subjective to the ship systems designer but the main distinction will most of the time be between at sea, in port and manoeuvring.
There will not be allotof electric equipment that require their maximum power continuously. Therefore we have to take into account several factors to create a more practical load
balance. If we would use every maximum demand the system will in the end be overpowered.
In Annex 1.D it is shown how the electric load balance for the typical cruise ship is composed. The results is shown in Table 1.6.
lop 20 30 40 50 60 70
Table 1.6: Electrical load balance for typical cruise ship
1.3.4 Steam load balance
In this section it will be tried to create a similar load balance of the heat demand on a cruise ship as is done for the electrical power demand. The Sun Princess will be taken again as an example. With the current technologies it is in fact not necessary to use steam on a ship. It is possible to meet the heat demand with electric heaters. Because of the big heat demand on cruise ships it is expected that it will still be more efficient to use steam instead of other heating methods. This is one of the reasons why it is tried to define initially a steam profile instead of an overall heat profile. The other reason is because it is out of the scope of this project to create a system of heat consumers with other technologies. It is preferred to use current practise.
Onboard the ship the heat transfer will be done by saturated steam. The pressure of the steam, if it is produced by oil fired boilers or waste heat boilers, is 9 [bar g]. The other steam
properties of saturated steam of 9 [bar g] are listed below in Table 1.7.
Table 1.7: Properties of saturated steam, 9 [bar g]
The steam consumption onboard the Sun Princess was also part of the information obtained from Princess Cruises. In Annex I .E the steam profile is constructed. Because of the fact that the temperature of the return feed water is unknown, the heat can not be expressed in [kW].
In order to be able to do so a return water temperature has to be assumed.
The steam load balance itself is shown in Table 1.8 and Table 1.9. The heat load balance is shown in Table 1.10 and Table 1.11. The assumed return water temperature is 100 [°C].
Operating level Power Demand [kW] Accum. time [°/0]
Summer At sea 10031 33.5 Manoeuvring 1 I 990 3.1 In Port 7488 16.3 Winter At sea 6406 28.0 Manoeuvring 9265 2.5 In Port 3863 13.6
9 [bar g] (-10[bar aasaturated steam
temperature 180 [°C]
specific volume of steam 0.19 [ms/kg]
density 5.24 [kg/m1
specific enthalpy of water 762 [kJ/kg] Evaporation heat 2015 [kJ/kg]
specific enthalpy of steam 2777 [kJ/kg I
Table 1.8: Steam demand as function of operating profile summer conditions
Table 1.9: Steam demand as function of operating profile winter conditions
Table 1.10: Heat demand as function of operating profile summer conditions
Table 1.11. Heat demand as function of operating profile winter conditions
Steam kg/h1 in summer Demand Operating level Evapo-rators FW Preheating Laundry Aircon-ditioning Galley San. FW heating Pool heating Total low 10816 - 236 1500 - 900 6000 2000 21452 man. - 70 1500 - 600 4200 - 6370 in port - 70 1500 - 600 4200 - 6370 Steam Ikg/h[ in winter Demand Operating level Evapo-rators FW Preheating Laundry Aireon-ditioning Galley San. FW heating Pool heating Total low 10816 300 1500 7800 900 6000 - 27316 man. 157 1500 7800 600 4200 14257 iii port - 157 1500 7800 600 4200 - 14257
lint
Demand 1 kW] in summer Operating level Evapo-rators FW Preheating Laundry A ircon-ditioning Galley San. FW heating Pool heating Total low 7087 155 983 - 590 3932 1311 14057 man. - 46 983 - 393 2752 - 4174 in port - 46 983 - 393 2752 - 4174Heat IkW1 in winter
Demand Operating level Evapo-rators FW Preheating Laundry - Aircon-ditioning Galley San. FW heating Pool heating Total low 7087 197 983 5111 590 3932 - 17900 man. - 103 983 511 I 393 2752 - 9342 in port - 103 983 5111 393 2752 - 9347 -I I
1.4 The WR21 intercooled and recuperated gas
turbine
The WR21 gas turbine distinguishes itself from the common simple cycle gas turbine by being intercooled and recuperated. The reason why it was required to develop such an engine can be explained with the theory of thermodynamics. A short discussion on this subject can be found in Annex 1.F.
Generally the WR21 consists of the following main components: Intermediate Pressure Compressor Intercooler
High Pressure Compressor Recuperator
Combustion Chamber High Pressure Turbine
Intermediate Pressure Turbine Variable Area Nozzles Low Pressure Power Turbine
This showed schematically in Figure 1.5. A full description of the engine structure is given in Annex 1.G. The same section will tell in what way it has been tried to achieve putting the benefits of intercooling and recuperating into a real engine. This also includes the US Navy performance requirements and the developing and testing program.
Intake
air
Intercooled-Recuperated Cycle
Exhaust gas
ACoolant
Sea-water
Recuperator
r+.
Fuel
IPC HPC_,HPT
!PT
On-engine
lntercooler
Variable
area nozzle
a1.5 WR21 Performance on a cruise ship
The optimum performance of an installed gas turbine is still limited by several factors. For a given fuel flow the output of the engine is restricted by the ambient pressure and the ambient temperature. But also the interfaces of the gas turbine with the atmosphere, the intake and the uptake, have an impact on the engine performance. Therefore we have to define the operating conditions of the cruise ship and we have to make a roughly made estimation on the pressure losses in the intake and the exhaust in order to know what the maximum power will be on the output shaft of the gas turbine.
1.5.1 The ambient pressure and ambient temperature
The temperatures of the thermodynamic cycle of a gas turbine will rise if the ambient temperature goes up. The maximum temperature at the hot end of the engine is a limiting factor to the envelope of the engine. Therefore one of the controls of a gas turbine is the maximum temperature control. This control makes sure that the maximum temperature is not exceeded even if the ambient temperature becomes higher than the design point temperature, but the result is that the maximum power of the engine decreases.
Therefore the maximum rated power of a gas turbine has to be made for a certain ambient temperature. It that case it is necessary to take a close look at the area where the gas turbine driven ship has to operate. The expected ambient temperature will differ all over the world. It will make a difference if the ship is operating at the North Sea or in the Caribbean. The cruise ship where the machinery configuration design is made for, is operating in the Caribbean and Alaska. The fact that the ship has to cruise in the Caribbean is the limiting factor, as will be explained in this paragraph.
To get an idea of the air temperatures at sea over the year in the Caribbean and Alaska, a table is made derived from a report, AN502 of Rolls Royce, which in its turn is derived from the Global Ocean Surface Temperature Atlas (GOSTA) of the UK Meteorological Office. This report uses data that had been collected from 1951 to 1993 and gives amongst others the mean air temperature at sea and the estimated maximum air temperature at sea, being the mean temperature plus three times the standard deviation which gives a 99% confidence level. The temperatures are measured at 15 metres above sea level and is therefore
representative for gas turbine intake temperatures. The mean and maximum air temperatures at sea level for Alaska and the Caribbean are given in Table 1.12.
As can be seen from the table the maximum air temperature is to be expected in the
Caribbean in September and equals 29.3 [°C]. A design point ambient air temperature of 30 [°C] will be a reasonable and practical value.
The ambient pressure does not have an explicit influence on the engine performance as the temperature has on the controls. Further it is harder to give an estimation for the mean air pressure than for the air temperature. Therefore the ambient pressure is taken for ISO conditions, which means a design point ambient pressure of 1.013 [bar].
Table 1.12: Mean and maximum air temperatures at sea in the Caribbean and Alaska
1.5.2 Intake and exhaust losses
The losses in the intake and the uptake of a ship are totally dependant on the design of the ducts. Every component has its own specific loss which on its turn is dependant on the flow through the component. We have tried to create a rough estimation of what the designs of the
intakes and the uptakes in a cruise ship could look like and made a pressure loss calculation for those designs
if
the gas turbine is running at 100% power both for the recuperator on and the recuperator bypassed. The different mass flows for those two operating modes will have an influence on the pressure losses in the ducts.In [Nurmi, 1996] an example is given for the intake ducts of a gas turbine driven 80 000 GRT cruise ship. This ship is actually designed as a comparison between a gas turbine- and a diesel-electric cruise ship. The gas turbine installation used is a General Electric Combined Gas turbine Electric and Steam (COGES) plant, which consists
of
two LM2500 gas turbines and a condensed steam turbine. The casing as used in the design is shown in Figure 1.6. As can be seen the air intakes are located on the sidesofthe ship and reasonably lower compared to convential naval ship designs. The design is rather complex but gives a smaller cross section flow area of the casing at the upper decks and it seems feasible. Mainly there are two things to be considered if the gas turbine intakes are mounted on the side.First it could be possible that under certain wheather conditions the air pressure on one side of a ship is significantly different from the pressure on the other side. Princess Cruises has reported that on the Oriana, where the intakes are located either side
of
the funnel in the deck house, the throughput of the axial fans for the machinery spaces could suffer a 30% reduction under certain wind conditions. No further specifications are given for those axial fans. However, having the intakes located either side of the funnel in the deck house, is a common configuration for the gas turbine intakes on a naval ship. The only difference between a cruise ship and a naval ship can be the size of the ship. The Invincible-class carriers of the Royal Navy have a size that is comparable to that of a cruise ship and they have the gas turbine intakes also mounted on the sides but even below the main deck. According to the spokesman of the Ministry OfDefence no practical difficulties have been reported regardingMean Air Temperature [°C] Maximum Air Temperature 1.°C]
Period Alaska Caribbean Alaska Caribbean
January 3.4 15.6 6.3 26.6 February 2.8 25.4 6.0 26.5 March 2.5 25.9 4.7 27.1 April 3.8 26.6 5.8 27.9 May 5.6 27.1 8.6 28.3 June 8.4 27.5 12.1 28.6 July 11.2 27.7 14.9 28.7 August 12.7 28.0 16.0 28.9 September I 1.1 28.1 13.6 29.3 October 7.9 27.7 10.4 28.8 November 5.1 27.0 7.8 28.1 December 3.1 26.1 5.0 27.3 , I , I I
splitter silencer: straight duct:
area changing bend:
plenum chamber:
intake filter:
The rest of the conditions are:
ambient pressure: ambient temperature:
intake air mass flow:
7 occx
LNk
length = length.= perimeter length S = bend radius =cross section width B =
cross section length H =
length = smallest height= width = height = width = 1.013 [bar] 30 [°C] 72 [kg/s] De-C7 mrr GALLEY
Figure 1.6: Gas turbine intake system for a cruise ship, [Nurmi,
19961
The second problem that could occur when gas turbine intakes are mounted on the sides is
the fact that water spray may cover the intake filters. This was a design consideration of Rolls Royce for the Invincible-class ships, because Harrier-planes have to hoover near the the
intakes and that causes a lot of water spray. This problem has been taken care of and the
filters that are used at most naval ships can cope with a lot of water spray. Thus also the
second consideration is no reason why the intakes can not be located on the side of a cruise
ship below the main deck.
For that reason we start with calculating the pressure losses in an intake system like in Figure 1.6. Following it from the engine to intake Filter the representative dimensions of the system are: SERV. CORR. CREW CABINS WW1 ..irr P1PCT2 5.0 [In] 5./ 8.8 [m] I m] 1.9 I in j 2.5 [m] (smallest) 11.5 1.6 [IT1] 3.5 [m] 2.9 m] [in]
DALLAS VIA ;TR DRY
2.6
Assuming air as an ideal gas the density of air, pa, can be calculated from:
288
pu=p15c
xTIsc = 1.226 xeq. 1.1
T is the temperaure measured in Kelvin. In our case this temperature is 303 [K] and therefore the density of air becomes 1.165 [kg/m3].
The ideal gas law with respect to volumetric gas flow is:
nxRxT cD,xRxT
cD,, =
eq. 1.2
In this R is the universal gas constant, which is 8314.51 [J/kmol.K], and Ma is the moleculair mass of air, which is approximately 28.97 [kg/kmol]. Hence for our situation:
72.0 x 8314.51 x 303
cD, = = 61.8
28.97x 1.013.105
eq. 1.3
The volumetric flow through the intake filter is 61.8 [m 3/s] and because the cross sectional area of the filter is 2.9 x 2.9 = 8.41 [m], the velocity of the air is 7.4 [m/s]. According to the
[Naval Engineering Standard 312, 1988] the pressure drop for a clean filter with that air velocity is 90 [mm wg], which equals 3.54 [in wg].
The pressure loss in the plenum chamber is low compared to the rest of the system because the plenum chamber is large compared to the ducts and therefore the velocity of the air through the plenum chamber is also low.
The [Naval Engineering Standard 312, 19881 gives a graph for the loss factor of a rectangular cross section constant area bend. In our case we do not have a constant area but the area decreases towards the engine. Therefore we use the smallest area to calculate the pressure
loss.
According to [Naval Engineering Standard 312, 1988] the loss factor for our bend is 0.45. The pressure loss for the bend is:
Pa xv2 APv = K x Pv = K x
2 x g
eq. 1.4
We have found that for the current ambient temperature the volumetric flow is 61.8 [m3/s] and with a cross sectional area of 2.5 x 1.9 = 4.75 [e] the velocity becomes 13.0 [m/s]. Hence the pressure loss over the bend is:
1.165 x 13.02
APv = 0.45 x = 4.5 2 x 9.81
eq. 1.5
The pressure loss is 4.5 [mm wg].
For the straight duct of 5.2 [m] length, a standard formula is given in [Naval Engineering Standard 312, 1988]. This equation is:
tPv=4fx
L x S x p" x v24 x Ad 2 x g
eq. 1.6
In this the factor '4r may be taken as 0.030 for all preliminary calculations. Thus the actual pressure loss becomes:
5.2 x 8.8 1.165 x 13.02
APv = 0.030 x =0.73
4 x 4.75 2 x 9.81
eq. 1.7
This is the pressure loss in [mm ww].
angle 13 Accelerator angle a Straight Duct Transition circular rectangular Recuperator
Gas Generator and Power Turbine
For the intake splitter silencer we may take a 50 [mm wg] pressure loss according to [Naval Engineering Standard 312, 1988]. This is a value to be taken for preliminary pressure loss calculations and is taken as the loss for our configuration.
The total calculated pressure loss for 100 % rating becomes the sum of all the component losses. This is 145 [mm wg] and equals 5.7 [in wg] and 1.42.103 [Pa].
The uptake system for our cruise ship design is a very simple one. The exhaust duct goes straight up from the engine to the upper deck. There is transition from the recuperator to the straight duct and at the end there is an accelerator to accelerate the exhaust gas. This is done to prevend particles in the exhaust gases to come down on the deck, which is uncomfortable
for the passengers. The exact dimensions will be dealt with later.
The total design used for the calculation of the pressure losses in the uptake system is shown
in Figure
Thecalculation starts with the pressure loss over the accelerator. Assume that the inlet of this component is called 1 and the exhaust is called 2, see Figure 1.8.
Figure 1.8
The ambient pressure, p2, is 1.013 [bar]. To know the velocity through the accelerator we have to know the volumetric flow and the cross sectional area through the accelerator. The mass flow in the exhaust is larger than the mass flow in the intake of the engine. This is caused by the fact that fuel mass and ventilation air has been added to the proces flow. The estimation is that the total mass flow is about 82.6 [kg/s] for operating in the recuperator bypassed mode. The corresponding temperature in the exhaust will be about 200 [°C]. We are going to use again the ideal gas law with respect to the volumetric flow assuming that the properties of air and the exhaust gases are not too different. In that case the equation
becomes:
1:3 xRxT
82.6x 8314.51 x473= 110.7
Ma XP 28.97 x 1.013 105
eq. 1.8
The volumetric flow is 110.7 [m3/s]. Assuming that the diameter of the straight duct is 2 [m] the cross sectional area of the intake of the accelerator is 3.14 [m-] and assuming a ratio of the areas at point 1 and point 2 of 1.5, the cross sectional area at 2 is 2.1 [m].
Accelerator
In that case the velocity at the discharge end becomes 52.9 [m/s]. As will be shown later this is a design consideration but the whole calculation is put into a worksheet and the results can be altered later.
In [Spiers, 1962] is given that the losses in a contractor like our accelerator are 5% of the dynamic pressure head at the exhaust if angle a is lower than 15 degrees. The dynamic pressure head in our case is:
v,2 82.6 52.92 Pv= p, X v2 = 2 cl''m X = X =106.3 [mm wg] 2 x g Or 2 x g 110.7 2 x 9.81 eq. 1.9
The losses are 0.05 x 106.3 and equal 5.32 [mm wg].
The pressure loss calculation for the straight duct is the same as it has been done for the intake. Only now the equation is meant for a circular duct. In that case the equation is:
2
L
p x v
APv = 4f x x
D 2 x g
eq. 1.10
We assumed a value of 0.030 for 4f and a diameter of the straight duct of 2.0 [m]. Additional a straight duct length of 38 [m] is assumed, which of course can be altered later, but a few metres more or less does nor really influence the total pressure loss.
With those assumptions the pressure loss becomes:
APv= 0.030 x 38.00.7506 x 35.02x = 26.8 [mm wg]
2.0 2 x 9.81
eq. 1.11
It has to be noted that it is assumed that the velocity throughout the straight duct stays the same. Practically there will be a slight difference due to the pressure loss.
The transition from the rectangular cross sectional area at the exhaust of the recuperator to the circular cross sectional area of the straight duct means the last component pressure loss. Again this is a contractor as mentioned in [Spiers, 1962], so the pressure loss will be 5% if angle f3 stays below 15 degrees The problem is the fact that there is no uniform angle. Therefore is the minimum and maximum angle calculated. For a transition length of 2.0 [m] the minimum angle is 2.9 degrees and the maximum is 22.6 degrees. It is assumed that a pressure loss of 5% of the dynamic pressure head, Pv, is a good estimation.
To know the value of the dynamic pressure head one has to know the static pressure at the exhaust of the transition because the velocity at the inlet of the straight duct was assumed to be the same at the end but this is not true. The total pressure at the beginning of the straight duct minus the dynamic pressure head assuming a similar velocity gives an estimation of the static pressure. The static pressure at the end of the transition is 10418 [Pa]. The calculated volumetric flow with the ideal gas law gives a flow of 109.8 [in3/s], density of 0.7526 [kg/m3] and an air velocity of 34.9 [m/s]. The pressure loss of the transition becomes in that
case:
0.7526 x 34.92
APv = 0.05 x = 2.34 [mm wg]
2 x 9.81
The last pressure losses of the uptake system are the discharge losses at the exhaust of the
whole system. It has been calculated that the velocity of the exhaust gases at point 2 of the
accelerator equals 52.9[m/s1 and that the density is 0.7469. Hence the discharge losses:
0.7460 x 52.92
APvoischarge) =1 x 106.31 [mm wgil
2 x 9.81,
eq. 1.A3 'The sum of all the pressure losses in the uptake system is 140.7 [mm wg], which equals
13808 [Pa] and 5.54 [in wg]. As said the calculation method has been put into a worksheet
and with changing some of the parameters the final results change to.
1.5.3 The output of the WR21 on a cruise ship
The next step to the performance estimations of the WR21, regarding the design point conditions, will be made with the help of a WR2 I performance calculating program. To come to a final input to this program we have to follow an iterative process. This is amongst
other reasons because the program will use the input inlet and exhaust duct losses for the ISO
5 [°C] ambient condition and it recalculates the duct losses for the off design conditions.
The relationship used in the program' to recalculate is:
offdesign
Duct lossoffdesign =Duct lossdesignpoint x
CD
if)
design
eq. 1.14 The program does also not include the ventilation air in the exhaust duct loss calculations.
The mass and the temperature of the ventilation air, which enters the process flow just after the recuperator, will have an effect on the actual exhaust duct loss.
The result is that initial values for the duct losses have to be put in to start with and then the program needs to calculate the performance at an ambient temperature of 30 ['CI. The results will give the recuperator exhaust mass flow, the temperature at this point and the exhaust duct loss according to the program. Then we have to find the ventilation air mass flow and
the final temperature of the ventilation air. The total exhaust mass flow is the sum of both and the resulting temperature can then be calculated by:
CDowe
C
p rec-T +it
rye invent C P rem gm
Tfinal =
CD In n'L CPrec m vent C Prow
eq. 145 This temperature and the mass flow are further used 'in the worksheet to calculate the actual pressure loss and finally the input pressure loss has to be altered to see what the new recuperator exhaust flow, temperature and exhaust pressure loss will be. This process has to be repeated until the worksheet exhaust duct loss equals the exhaust duct loss of the program.
In that case will the performance of the engine be calculated correctly.
Summarising the design point parameters from the last paragraph gives:
Those are the input values to start with and going through the above explained process leads to a new input value for the exhaust pressure loss, which is 185 [mm wg] and results in an actual pressure loss of 237 [mm wg] for the worst case, which is 100% power in the recuperator bypassed mode.
The aim of this whole section was to know what the performance of the WR21 is in the defined design point. At first we are interested what the maximum power for those conditions is. The resulting maximum power of the WR21 operating with the recuperator on is 22.465 [MW]. This maximum power will further be used to set the 100% rating of the engine at this power for the rest of report. If the recuperator is bypassed, the maximum power will slightly increase to 22.978 [MW] due to the higher mass flow.
The maximum power is garanteed at the ambient temperature of 30 [°C] and below but will decrease as the ambient temperature goes up. This is shown in Figure 1.9.
For a machanicval drive the design point will be the point where the cube law passes the maximum power turbine speed of the WR21, which is 3600 [rpm]. Left from the design point in Figure 1.9 the performance of the WR21 will be limited by the power turbine speed whereas on the right side the maximum temperature in the engine is limiting the engine performance.
25000
20000
WR21 Performance rating (caribbean cruise ship)
15000
10000
0 5 10 15 20 25 30 35 40 45 50
Ambient Temperature [deg CI
Figure 1.9: Relation between the power output and ambient temperature of a Ambient Pressure 1.013 [bar]
Ambient Temperature 30 [°C]
Intake pressure loss 145 [mm wg]
0.3500 0.3000 0.2500 0.2000 0.1500 0 03500 0.3000 01500 0.2000 0.1500
SFC-curve WR21 recuperator on
WEIN= MIN HIM MMIOIMM. MEM
MMMINIMMMMIMMIMOIMMIIIMM MMUMMMIMMMMMMMMMEIMMMIMMIIIM
Imiammommemmimmmmilm...
mom'MCOMMMEMOMMEMMEMMEMIN
ummiummommommummimmmmmomME NOMMESOMMOMOMMOMOMMOMOM MMEIMMMOIMMOMMINMIMMANIMM IMMMMOIMMIMMIIIIMMINUMMMIMM MIIIMMMEMOIARIEMMMMMMMEMMMEMmmIlIMMMEMAlm!=,, MMMMMMMMMIWIMMMIIIMUMMIMM ---WIIMMMMIIIIMMIMMIMMIMM MI MAIMMIMMIMMMINMMM=MM MWMIMMSFC-curve WR21 recuperator bypassed
111111111111MOMMMWMMIMMIMMMIMMIMMMMOIM MMOOMMMMM=MEMMIIIIMMIIIMMIMM MMMMMMMEIMMMWIIIIMMMOMMIMM mmiummmmmmilmmmommummemommummommo mummommummommommaimmimm... Immmmmmmmmmmmmmmmmmmmmmimmmmmmmm mmmmmmmmmmmmmmmmmmimftmmmmm mwmmmmwmmmmmmmmmmmmmmmmmmmi. immmmemmmirmilmmommummmilmm... mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmi OmMOMMOMMOMMOMMEMOMOOMI Im'Mmmmmimmmimmmmmmmmmmmmummmmmmmmmmmmm mmommmummummmommmmimmmummmmummmme mm.mmommummommummummmilmlimmomm immmmmmmmmmmmmmmmmmmmm gm imammommommommilmimemmmummomm. mil mown
limm...
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Figure 1.10: SFC curves for WR21 cruise ship conditions
In case of a WR21 that is driving a generator at a speed of 3600 [rpm], the power turbine speed has to stay constantly at 3600 [rpm] for a constant output frequency. So in Figure 1.9 it is possible for the WR21 to go up in power output on the left side of the design point,
because the engine is not fixed to the cube law. But practically the design point of the WR21 will also be the design point of the generator unless it is wanted that the generator is capable to deliver more power with the penalty of higher cost. In that case the definition of a design point would make no sense.
Further it is also possible to give the specific fuel consumption of the engine at full power and part power. The WR21 performance calculation program is also giving those values for the recuperator on and bypassed. The results on this matter are shown in Figure 1.10. The program was not capable of giving the results in recuperator bypass mode below 40% of maximum rating.
Power irA
0 20 40 60 80 100
Power rid
2.
Cruise ship machinery
configurations with the WR21
In the previous section it has been discussed what the requirements are of a typical cruise
liner and what the performance is of the WR2I. Those are the prerequisites for actually matching the WR21 attributes to the propulsion and domestic requirements of a cruise ship. In the following section it will be tried to compose machinery configurations with WR21 gas turbines that meet those requirements. The configurations that will be considered are:
The WR21 gas turbine electric configuration
The WR21 gas turbine electric configuration with waste heat boilers
The WR21 gas turbine electric configuration with an additional prime mover The WR21 gas turbine electric configuration with waste heat boilers and an additional prime mover
In every configuration each component that is used has to be defined. Therefore components
like generators, propulsion systems and boilers are selected in the beginning of each section.
After the components have been chosen the total plant performance of each configuration option can be determined in terms of produced power, produced heat and time. This is done with the help of the total energy demand profile, defined in the previous chapter.
