the analysis of thermal-oil heating systems with exhaust

Zeszyty Naukowe 24(96) 33

Scientific Journals Zeszyty Naukowe Maritime University of Szczecin Akademia Morska w Szczecinie

2010, 24(96) pp. 33–40 2010, 24(96) s. 33–40

The analysis of thermal-oil heating systems with exhaust gas heaters on motor ships

Analiza olejowych systemów grzewczych z nagrzewnicami utylizacyjnymi na statkach motorowych

Ryszard Michalski, Wojciech Zeńczak

West Pomeranian University of Technology, Faculty of Maritime Technology Department of Heat Engines and Marine Power Plants Zachodniopomorski Uniwersytet Technologiczny, Wydział Techniki Morskiej Katedra Maszyn Cieplnych i Siłowni Okrętowych 71-065 Szczecin, al. Piastów 41, e-mail: [email protected], [email protected]

Key words: ship’s heating system, thermal oil heater, exergetic analysis

Abstract The article characterises the properties of steam and special thermal oils as the basic heating media on motor

ships. The features of the heating installations have been presented with the particular attention drawn to

thermal oil installations in which exhaust gas heaters have been employed. Also an example of the

comparative exergetic analysis has been included demonstrating the comparison between steam generation in

exhaust gas boiler and oil heating system in the heater, assuming the identical heat flux transferred in the

boiler and the heater from the exhaust gas to the heating medium (steam and thermal oil) and assuming

identical increase of exhaust gas entropy in the heat exchangers under examination.

Słowa kluczowe: okrętowy system grzewczy, nagrzewnice olejowe, analiza egzergetyczna

Abstrakt W referacie scharakteryzowane zostały własności pary wodnej i specjalnych olejów grzewczych jako pod-

stawowych czynników grzewczych na statkach motorowych. Przedstawiono cechy instalacji grzewczych ze

szczególnym uwzględnieniem instalacji olejowych, w których występują nagrzewnice utylizacyjne. Zamiesz-

czono także przykład porównawczej analizy egzergetycznej systemu wytwarzania pary w kotle utylizacyjnym

oraz systemu podgrzewania oleju w nagrzewnicy przy założeniu jednakowego strumienia ciepła przekazywa-

nego w kotle i nagrzewnicy od spalin do czynnika grzewczego (pary wodnej i oleju) oraz przy założeniu jed-

nakowego przyrostu entropii spalin w rozpatrywanych wymiennikach ciepła.

Introduction

Mostly steam and special thermal oils have been

applied as heating media on ships. Water or hot air

have been used in a lesser degree and electric

energy is used just occasionally. To obtain the high

temperature of the heated media by using such

media as water or steam it is necessary to apply

sufficiently high pressure. The high pressure of

steam is also necessary to make up for the pressure

losses in the long cargo heating pipelines on some

tankers. This fact increases the risk of the loss of

tightness and steam leakages and its condensate to

the heated working media as well as to the cargo.

This is absolutely not allowed, in particular while

heating the concentrated acids and bases or liquid

sulphur. In such cases, as well as on many other

ship types, the special thermal-oils have been used

as heat carriers which are characterised by the

relatively stable physical and chemical properties

within the broad range of the changes of their

working temperatures. Additionally the oil heating

systems are significant for their higher efficiency

values as compared to the steam systems, do not


34 Scientific Journals 24(96)

post the corrosion danger, are suitable for the full

automation which allows their unmanned operation.

The heat source in the ship’s heating systems is the

energy coming from the combustion of fuels in the

steam boilers or oil heaters. On the motor ships in

high degree the waste heat energy is used in the

form of the heat contained in the main engines

exhaust gases.

Steam heating system

In the heating technology the saturated steam

(dry or humid) is generally used, less frequently

the slightly superheated steam. The advantage of

the steam in relation to the other heating media is

its constant temperature within the condensation

process. The significant parameters of steam, as the

heating medium, are the temperature and saturation

pressure. As generally known, these values are

closely interrelated. Thus the application of high

pressure steam requires adequately high pressure

values throughout the entire installation. The steam

working temperature determines indirectly the

required strength of the equipment used in the

steam installation.

Another important parameter is the water evapo-

ration specific enthalpy whose value decreases

together with the pressure rise and the increase

of the saturation temperature. It reaches the value

equivalent to zero in the critical conditions (pk =

22.1 MPa, Tk = 647.3 K). From this point of view in

the heating installations there should be used steam

of low pressure corresponding to the large value of

the evaporation enthalpy. Within the practically

used pressure range the value of the saturated steam

specific enthalpy increases together with the pres-

sure rise. The heating steam higher pressure values

correspond to its higher density which allows the

application of lower diameter pipelines. However,

it should be reminded that together with the pres-

sure increase the water evaporation specific en-

thalpy decreases which affects the heat exchange

surface of the heaters. The finally adopted working

parameters of the heating system are usually based

on compromise. However it should be emphasised

that the choice of the heating steam pressure chiefly

depends on the temperature values to which the

working media are to be heated in engine room.

In the engine rooms of the ships which do not carry

the heating requiring cargo the saturated steam

under 0.4–0.8 MPa is used which correspond to the

saturation temperature 416.75–443.57 K accord-

ingly. The steam pressure values on tankers reach

as high as 1.2 MPa (saturation temperature of

461.1 K). The reason to choose the higher pressure

values in such cases are inter alia larger pressure

drops of steam in the long pipelines, a possibility of

the reduction of the steam supply piping diameters,

the reduction of heat exchange surface resulting

from the higher temperatures and the ensuring of

the heating medium and condensate flow without

any additional equipment [1].

The condensate leaving the heaters is cooled

down to the temperature approximately 343 K in

the condensate cooler or in case of not excessively

high temperatures – in hotwell. This operation is

necessary to provide the protection for the boiler

feed pump against cavitation and water evaporation

in the suction stub pipe. However it causes some

significant heat losses in the steam-water installa-

tion thus visibly reducing the efficiency of the

steam heating system.

Oil heating systems

The heating oils can be divided on account of

their origin into the mineral and synthetic ones. The

mineral oils, of natural origin, consist the mixture

of many hydrocarbons, amongst which the satu-

rated paraffin hydrocarbons are of the biggest im-

portance. The chemical structure of mineral oils is

very much varied and depends to a large extent on

the origin of the raw material and the methods of its

processing in the refineries. In the effect the proper-

ties of the mineral oils are hardly reproducible and

keep on changing in various manners during the

use. The mineral oils may be used in the heating

systems where the temperature of the medium does

not exceed 593.15 K. In case of the necessity to use

higher working temperatures the synthetic oils are

applied which are the products of closely monitored

chemical synthesis. Their chemical composition is

more stabilised therefore they are easier reprodu-

cible in the production in various factories which

means keeping their properties as the same. Since

the majority of the motor ships has no need to heat

the working media up to very high temperatures,

and the heat supply to the thermal oil is effected

mainly in the exhaust gas heaters, the preferable

heat carriers are the mineral oils. At the same time

these are cheaper than the synthetic oils, easier

available and non-toxic.

The thermal oils of less density have better

thermal properties and provide better heat condu-

ctivity. In case of thermal oils an important parame-

ter is their viscosity because it influences the flow

rate and nature, thus the intensity of the heat ex-

change and provides the possibility of oil pumping

in low temperatures. The relatively low viscosity of

thermal oils and the large value of viscosity index



ensures the high coefficients of heat exchange and

the constant properties within the wide temperature

range as well we facilitates oil circulation while

starting the heating system in low temperatures.

Another significant parameter is also the solidifica-

tion temperature. This is used to evaluate the pos-

sibility of oil storage and transfer and its flow

capacity inside the gravity-supplied system in low

temperatures.

The mineral oils as opposed to the popular

synthetic oils are characterised by the vapour low

pressure (the less as the higher oil viscosity is).

At the maximum working temperature it is usually

lower than the atmospheric pressure owing to

which it is possible to use so called non-pressure

heating systems. In case it is necessary to use the

higher temperatures, the need arises to apply, eg

inside expansion tank, a minor overpressure of the

inert gas, usually nitrogen or the adoption of the

hermetic installations to prevent the formation of

the vapour-locks.

The minimum working temperature of the

heating system is determined by the oil capacity to

circulate through the heater prior to its starting. The

minimum temperature determinant is the corres-

ponding oil viscosity with which the pumps are still

capable of oil pumping (ca 300 cSt) [2].

Theoretically, in the oil heating installation the

oil may be heated below the temperature deter-

mining the beginning of its boiling (the temperature

where the oil vapour pressure is equal to the

ambient pressure). In practice the upper working

temperature is limited by the value where oil

thermal decomposition rapidly increases).

An important parameter is the specific heat ca-

pacity of the heating medium. It influences the in-

tensity of its heat transfer in the heating systems.

A strong relation of its value to the temperature

should be noted. For example at the temperature of

273.15 K the mineral oil heat capacity ranges

within 1.76–1.83 kJ/kgK), whereas at the tempera-

ture of 573.15 K it ranges within 2.83–3.02 kJ/kgK.

The heat capacity values of the synthetic oils are

less than those of the mineral oils [2]. As can be

seen these are values approximately twice less than

for the water. This means that the oils require twice

as big flow (larger energy consumption) or the

increase of the heat flux in oil heater (large and

expensive boilers).

The heat conductivity of the mineral oils which

is of major significance in the heat exchange, at the

temperature of 273.15 K ranges within 0.129–0.135

W/mK, whereas at the temperature of 573.15 K it is

within 0.11–0.114 W/mK [2]. This is higher than

the specific heat capacity of the synthetic oils.

Oil during the operation within the heating sys-

tem changes its chemical properties which is collo-

quially referred to as the oil deterioration. These

changes are mainly caused by the oxidation and

thermal cracking, particularly in higher tempera-

tures. The visible results of oil deterioration are the

collecting of harmful substances such as resins and

coal sediments. The sediments are partly suspended

in oil and partly precipitated and deposited on the

parts of the installation, and the additionally gene-

rated organic acids have a corroding effect on

metals. Also oil viscosity changes in a high degree

in the result of the generation of compounds of

larger molecular weight [3, 4].

Exergetic analysis [5] may become helpful for

the calculations of the thermal processes, particu-

larly effected within the relatively low temperatures

of the working media. For this purpose it is useful

to find the specific exergy of the working media

participating in the processes under investigation.

Assuming that the oil pressure does not exceed

0.3 MPa or is equal to the ambient pressure (in the

non-pressure systems) and that the specific heat

capacity value is constant, its specific exergy can be

calculated from the equation (1).

ot

ototpfTT

TTTTcb ln (1)

where: cp – oil specific heat capacity, T – oil tem-

perature, Tot – ambient temperature.

On the basis of this relation the calculations of

the exergy of the synthetic and mineral oils have

been conducted at the ambient temperature of

303.15 K within the oil temperature variations

within 313–633 K. The course of the changes of the

oil specific exergy in the unction of its temperature

is shown in figure 1. On the other hand the figure 2

shows the density of exergy for the oils and steam.

In comparison with the water and steam the

exergy of oils is less. However, the density of the

oil exergy is significantly bigger than the density of

steam exergy, particularly within the high tempera-

ture range. It should additionally be noted that the

obtainment of the same temperatures for water and

steam as well as for oil is connected with the

necessity to apply very high pressures.

In the heat exchange systems the oil oxidation

possibilities are limited since this is only in the

expansion tank that the oil gets in contact with the

air. The air whose solubility in oil reaches as far as

nearly 10% volume may also enter the system

through minor leakages [2].

The oils used in the heating systems are charac-

terised by the high thermal stability and good resis-



tance to oxidation within the temperature ranges

occurring in service. Owing to that the rate of their

decomposition and oxidation is small which en-

sures long period of oil usability without formation

of sludge and sediments which are likely to be the

cause of the disturbances in the operation of the

heating system. It should be noted that the synthetic

thermal oils ensure better thermal stability and

higher resistance to oxidation as compared to the

mineral oils.

The most important feature thanks to which the

thermal oils tend to substitute the steam as the

heating medium is the possibility of their appli-

cation at the low values of the working pressures

whose value depends almost entirely on the flow

resistance in the heating installations. Thermal oil

installation is either the installation of the open

type, “non-pressure” (the oil compensation tank is

connected with the atmosphere), or the closed type,

low-pressure with pressure values not exceeding

0.1–0.3 MPa [6]. This enables to obtain the

temperatures up to 593.15 K for mineral oils or

up to 633.15 K for the synthetic oils remaining in

the liquid stage. The achieving of such high tempe-

ratures of the heating steam would require the

application of significantly more expensive, high-

-pressure steam installation. Therefore the first

ships where the oil heating system has been applied

have been the tankers designed to carry heavy

petroleum products, eg bitumen, asphalt where the

required heating up temperatures are in the order of

493.15 K (the application of the steam system

would necessitate the used of steam under 4 MPa).

In case of the application of the cargo thermal oil

heating, the system generally is used also to cover

the remaining heating needs of a ship.

In the open type installations oils of large

viscosity are used which are characterised by the

high flashpoint ensuring better work safety. The

closed type installations with oil of low viscosity

are, however, more efficient [2].

In case the heating installation is put out of

operation, the application of oil to heat up the

petroleum product cargoes eliminates the possibi-

lity of the petroleum products entering the heating

medium which might take place in the steam

heating systems. This phenomenon is prevented by

placing the oil expansion tank at the highest point

of the entire installation [7].

If on ship’s board there is a need of steam, eg to

conduct the technological processes (on fish factory

trawlers, for tank cleaning, ice removal etc), it can

be additionally produced in the steam generators

heated with thermal oil.

The overall thermal efficiency of the thermal oil

installation, reaching the value within 0.75–0.85, is

higher than the efficiency of the steam installation

(0.55–0.65) owing to the elimination of the heat

losses occurring in the steam installations at the

condensate side. Also the working medium losses

in the thermal oil installations are smaller than the

medium losses in the steam heating installations

[7].

Owing to the possibility to apply the higher

temperatures of the working medium in the thermal

oil installations, there is no need to increase the

heat exchange surface, and the low pressure pre-

vailing in these installations causes that the invest-

ment costs of such installations do not increase in

comparison to the conventional steam installations.

An opportunity to reduce the heat exchange surface

within the oil heating process is the application of

the fluidised-bed heaters, both for exhaust gas as

well as the independent, oil-fired ones.

Fig. 1. The physical specific exergy values for the synthetic

and mineral oils and dry saturated steam in the function of the

temperature Tot = 303.15 K

Rys. 1. Egzergie fizyczne właściwe olejów: syntetycznego

i mineralnego oraz pary wodnej nasyconej suchej w temepera-turze Tot = 303,15 K

Fig. 2. The density of the physical exergy values of synthetic

and mineral oils and dry saturated steam in the function of the

temperature Tot = 303.15 K

Rys. 2. Gęstość egzergii fizycznych olejów: syntetycznego

i mineralnego oraz pary wodnej nasyconej suchej w funkcji

temperatury Tot = 303,15 K

Sp

ecif

ic e

xer

gy,

kJ/

kg

E

xer

gy d

ensi

ty, k

J/m

3

Temperature, K

Temperature, K

Min. oil Synth. oil Steam

Min. oil Synth. oil Steam



The basic arrangements of the thermal oil heating installations with the exhaust gas heaters

In order to increase the general efficiency of

ship’s engine room / power plant there are used the

combined systems of thermal oil heating of the

heating medium in the independent heater and in

the exhaust gas heater utilising the main engines’

and at times also auxiliary engines’ exhaust gases.

Both heaters can operate separately and / or jointly,

ie in the parallel or series set-up. In the series

operation as first the low temperature exhaust gas

heater is applied. The parallel connection is applied

in case when the large heat amounts are necessary

for the cargo heating in cargo tanks of the ship. The

oil-fired heater is automatically started, if the heat

needs exceeds the exhaust gas heater production

capacity. The figure 3 shows for instance the instal-

lation with the exhaust gas heater operating in the

series set-up with the independent heater.

Thermal oil heating installations with the inde-

pendent and exhaust gas heater can totally replace

the steam installations on the majority of ships.

Most frequently they are employed on: tankers for

the carriage of high viscosity petroleum products,

container ships, fish factory trawlers operating in

Arctic waters, chemical tankers, ice-breakers.

In case of ship’s indirect propulsion with two

medium-speed Diesel engines it is possible to apply

two exhaust gas oil heaters which may operate in

the parallel system or the series system (Fig. 4).

Operation in the series system with the independent

heater is also possible. Such arrangement provides

possibilities of the heating system operation with

various connection versions. This enables rational

generation and use of energy [8].

More complex thermal oil installations are ap-

plied on tanker used for the carriage of molten sul-

phur. The sulphur during the transport should be

stored at the temperature within 408.15–423.15 K

when it shows the smallest viscosity and does not

change its properties. The temperature increase

above this value causes that the sulphur viscosity

increases and it densifies around heating coils stick-

ing to the pipes, which in effect creates their

Fig. 3. Oil heating installations by means of the independent and exhaust gas heaters operating in the series set-up; 1 – independent

heater; 2 – exhaust gas heater; 3 – expansion tank; 4, 5 – circulating pumps; 6 – drain tank; 7 – storage tank; 8 – topping-up

pump / replenish pump; 9 – oil cooler; 10 – deaerating heater [2]

Rys. 3. Instalacja podgrzewania oleju nagrzewnicą niezależną i utylizacyjną w układzie szeregowym; 1 – nagrzewnica niezależna;

2 – nagrzewnica utylizacyjna; 3 – zbiornik wyrównawczy; 4, 5 – pompy cyrkulacyjne; 6 – zbiornik ściekowy; 7 – zbiornik zapaso-

wy; 8 – pompa uzupełniająca; 9 – chłodnica oleju; 10 – podgrzewacz [2]

to the consumers

from the consumers



efficient thermal insulation. This necessitates the

application of the system with the heating medium

of two different temperatures, the lower, not ex-

ceeding 433.15 K in the sulphur heating installation

and the higher, in the engine room’s heating instal-

lation and ship’s general installation. One of the

solutions may be two-line circulation installation

where the thermal oil of lower temperature is

heated in the heater by the high temperature circu-

lation line oil [6].

Finally the choice of a given heating system are

chiefly determined by the cargo heating conditions,

costs of construction and operation of the instal-

lation.

The manufacturers of the thermal oil heating

systems assure that the heater heat exchange

surfaces should not be bigger than in the steam

installation, if oil temperature not less than 533 K is

assumed. However, choosing such temperature put

out of the question the application of exhaust gas

boiler operating independently. It is only possible

for the boiler to operate in the series set-up with the

oil-fired heater which would heat up the oil. Such

system, however, does not offer such energy

savings as the parallel system with the exhaust gas

heater operating independently while at sea. This

will be connected with the increase of the heat

exchange surface of the heaters. The preliminarily

conducted calculations have proven that in case of

eg engine room’s tank heating coils the total length

of the pipes has increased by approximately 30% in

relation to the length of the heating coils in the

steam system [2].

Exergetic analysis of the heat exchange process in the steam-water boiler and oil heater

The calculations have been carried out under

assumption of the identical heat flux transferred in

the boiler from the exhaust gas to the heating

medium (steam or oil) and under assumption of the

identical increase of the exhaust gas entropy in both

kinds of heaters.

Do odbiorników

Z odbiorników

3

6 8

9

11

4 5

7

10

to the consumers

from the consumers

Fig. 4: Thermal oil heating system with two exhaust gas heaters; 1 – storage tank; 2 – drain tank; 3 – independent heater; 4, 5 – ex-

haust gas heaters; 6 – oil surplus cooler; 7 – transfer pump; 8, 9 – circulating pumps; 10 – expansion tank; 11 – deaerating heater [8]

Rys. 4. Olejowy system grzewczy z dwiema utylizacyjnymi nagrzewnicami; 1 – zbiornik zapasowy; 2 – zbiornik ściekowy;

3 – nagrzewnica niezależna; 4, 5 – nagrzewnice utylizacyjne; 6 – chłodnica nadmiarowa oleju; 7 – pompa transportowa; 8, 9 – pom-

py obiegowe; 10 – zbiornik ekspansyjny; 11 – odgazowywacz [8]



The ratio of the increase of the entropy of the

heating media (steam and oil) has been determined

as:

wzpp

ol

olpolol

p

ol

ssm

T

Tcm

S

S

ln

(2)

ololpol

wzpp

olTTc

iimm

(3)

thus:

ololwzp

ol

olwzp

p

ol

TTss

T

Tii

S

S

ln

(4)

where: pol mm , – stream of oil or generated steam;

pp is , – entropy and specific enthalpy of the steam

at the saturation line; wzw is , – entropy and specific

enthalpy of the boiler feed pump; olol TT , – thermal

oil temperature at the heater outlet and inlet; polc –

thermal oil specific heat capacity (constant value

assumed).

For the purposes of comparison of the steam and

oil systems the constant value of the oil temperature

has been assumed at the return to the heater (Tol1 =

303.15 K). On the other hand, the temperatures of

boiler feed water (Tw1) have been changed within

323.15–343.15 K. As displayed by the calculations

performed, the increase of the temperature of both

media at the outlet from the heat exchangers, with

the assumed identical exhaust gas entropy incre-

ases, bigger increases of the entropy of the thermal

oil do occur than the increases in water and steam

entropy. This leads to the bigger increase of entropy

within the process of oil heating as compared to the

water and steam heating. This is the result of the

faster drop in entropy increase in the steam

generation process in relation to the thermal oil

heating system. However, it should be noted that

the higher temperatures of steam correspond to

higher saturation pressures and lower evaporation

enthalpy. The courses of the changes in the entropy

increases are illustrated by the curves in figure 5.

It should be noted that the increase in the boiler

feed water temperature is accompanied by the

growth of the ratio of the increase of the oil entropy

to the increase of water and steam entropy. Similar

as in figure 5 is the nature of the course of the

curves in figure 6, illustrating the ratio of the in-

crease of the entropy of oil to the increase of the

entropy of water and steam in the function of the

heating media temperature for the various tempera-

tures of oil at the heater inlets with the boiler feed

water constant temperature (Tw1 = 303.15 K).

1.08

1.09

1.10

1.11

1.12

1.13

1.14

1.15

1.16

425 435 445 455 465 475 485 495 505 515 525 535 545 555 565 575

Rat

io o

fth

e en

tro

py

in

crea

ses

of

ther

m.

oil

an

d w

ate

r an

d s

team

Temperature, K

Tw1 = 323.15 K

Tw1 = 333.15 K

Tw1 = 343.15 K

Fig. 5. The ratio of the increase of the oil entropy to the

increase of the water and steam entropy in the function of the

temperature of the heating media for various temperatures of

boiler feed water Tw1. Oil temperature at the heater inlet Tol1 =

343.15 K

Rys. 5. Stosunek przyrostu entropii oleju do przyrostu entropii

wody i pary w funkcji temperatury czynników grzewczych dla

różnych temperatur wody zasilającej kocioł Tw1. Temperatura

oleju na wejściu do nagrzewnicy Tol1 = 343,15 K

0.97

0.98

0.99

1.00

1.01

1.02

1.03

1.04

1.05

1.06

1.07

445 455 465 475 485 495 505 515 525 535 545 555 565 575

Rat

io o

fth

e en

tro

py

in

crea

ses

of

ther

m.

oil

an

d w

ate

r an

d s

team

Temperature, K

Tol1 = 400.15 K

Tol1 = 423.15 K

Tol1 = 443.15 K

Fig. 6. The ratio of the increase of oil entropy to the increase

of water and steam entropy in the function of the heating media

temperature for the various temperatures of thermal oil Tol1.

The temperature of boiler feed water Tw1 = 303.15 K.

Rys. 6. Stosunek przyrostu entropii oleju i pary w funkcji

temperatury czynników grzewczych dla różnych temperatur

oleju grzewczego Tol1.Temperatura wody zasilającej kocioł

Tw1 = 303,15 K

The increase in the working media temperature

causes that the ratio of the entropy increase of the

oil in oil exhaust gas heater in relation to the entro-

py increase of the water and steam in exhaust gas

boiler grows. With the lower temperature range the

increases of entropy in the oil boiler may be lower

than in the steam boiler. The increase of the oil

Tw1 Tw1 Tw1

Tol1

Tol1

Tol1

Rat

io o

f th

e en

tro

py

incr

ease

s o

f th

em.

oil

and

wat

er a

nd

ste

am

Rat

io o

f th

e en

tro

py

incr

ease

s o

f th

em.

oil

and

wat

er a

nd

ste

am



temperature on the return line to the heaters causes

that entropy increases get less, thus the ratio of the

increase of entropy of the oil system in relation to

the steam system gets smaller for the same values

of oil and water temperatures at the outlets of the

boilers. This is the case in the actual systems where

the thermal oil temperature at the return to the hea-

ter is significantly higher than the boiler feed water

temperature.

The analysis conducted covered only one link in

the entire chain of transformations related with the

heating process on a ship. Similarly conducted

analysis for the remaining elements of the whole

heating system will allow to fully evaluate their

efficiency. The outline of such analysis has been

presented in [8].

Conclusions

The analysis of the thermal oil systems pre-

sented in the article shows that they might form

a good alternative for the steam system which is

nowadays commonly used on the majority of ships.

The advantages of the thermal oil system have been

observed and appreciated already long ago, inter

alia in the German shipyards where ships are very

often equipped with the installations of such type.

The shipowners reluctance to the application of

such solutions may result from the limited know-

ledge of the thermal oil systems. The smaller heat

exchange surfaces in the steam-water installations

in comparison to the oil systems are accompanied

by the high costs of the high pressure installation

and the steam boiler itself as well as the additional

equipment such as boiler water treatment plant,

inspection tanks, condensate cooler, dehydrators

etc. as well as their lower efficiency. The economic

advantages to be achieved through the application

of the thermal oil systems include amongst others

fuel savings and the savings of the ship’s mainte-

nance costs owing to their longer life and unat-

tended / unmanned operation.

References

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The study financed from the means for

the education within 2009–2012 as own research

project No. N N509 404536.

Recenzent:

dr hab. inż. Andrzej Adamkiewicz, prof. AM

Akademia Morska w Szczecinie

the analysis of thermal-oil heating systems with exhaust

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