A sample of shoppers was selected and asked questions regarding co.docx

A sample of shoppers was selected and asked questions
regarding consumer behavior. One of the questions asked was
"Do you enjoy shopping for clothing?" Information regarding
the responses is below:
· Total Responses: 500
· Males: 136 responded "yes" and 104 responded "no"
· Females: 224 responded "yes" and 36 responded "no"
Construct a contingency table summarizing the above results
and answer the following questions:
1. What is the probability a shopper likes to shop for clothing?
2. Given a shopper is male, what is the probability the shopper
likes to shop for clothing?
3. Given a shopper is male, what is the probability the shopper
does not like to shop for clothing?
4. Given a shopper is female, what is the probability a shopper
does not like to shop?
Renewable Energy 28 (2003) 873–886
www.elsevier.com/locate/renene
Technical and economical evaluation of solar
thermal power generation

Theocharis Tsoutsosa,∗ , Vasilis Gekasb, Katerina Marketakib
a Centre for Renewable Energy Sources (CRES), 19th km
Marathon Avenue, 19009 Pikermi, Greece
b Department of Environmental Engineering, Technical
University of Crete, Crete, Greece
Received 23 July 2002; accepted 24 July 2002
Abstract
This article presents a feasibilty on a solar power system based
on the Stirling dish (SD)
technology, reviews and compares the available Stirling engines
in the perspective of a solar
Stirling system.
The system is evaluated, as a parameter to alleviate the energy
system of the Cretan island
while taking care of the CO2 emissions. In the results a
sensitivity analysis was implemented,
as well as a comparison with conventional power systems.
In the long-term, solar thermal power stations based on a SD
can become a competitive
option on the electricity market, if a concerted programme
capable of building the forces of
industry, finance, insurance and other decision makers will
support the market extension for
this promising technology.
Keywords: Technical and economical evaluation; Solar
electricity generation; Solar thermal power; Stir-
ling engine

1. Introduction
The electrical generating demand has increased in the island of
Crete due to the
economic growth during recent years. The rate of this increase
becomes dramatical
during the summer. Conventional fossil fuel plants generate the
electricity and this
∗ Corresponding author. Tel.:+30-1603-9900; fax:+30-1603-
9904.
E-mail address: [email protected] (T. Tsoutsos).
0960-1481/03/$ - r Science Ltd.
All rights reserved.
PII: S 0 9 6 0 -1 4 8 1 ( 0 2 ) 0 0 1 5 2 - 0
874 T. Tsoutsos et al. / Renewable Energy 28 (2003) 873–886
energy production cost is very high (Table 1); this cost can be
higher in other Greek
islands [1].
The power generation should be increased over the next years in
order to satisfy
the power demand. The new power plants should be
environmentally since there
already exist some conventional fossil fuel power plants in the
island.
Crete is very rich in renewable energy sources. In this paper the
option of the
establishment of solar thermal power station based on Stirling
dish (SD) technology

is evaluated to alleviate the energy system of the island.
The system can be a clean and efficient solution to the major
energy problem of
the island[2].
2. Solar Stirling engines
2.1. Solar thermal electric technology
Solar thermal electric power generating systems incorporate
three different
design alternatives:
� Parabolic trough collector: focus systems that concentrate
sunlight onto tubes
located along the focus line of a parabolic-shaped reflective
trough.
� Power tower: focus central receiver systems that use large
fields of sun-tracking
reflectors (heliostats) to concentrate sunlight on a receiver
placed on top of a
tower.
� Parabolic dishes: focus dish systems reflect light into a
receiver at the dish’ s
focus [3,4].
Exceptional performance (almost 30%) has been demonstrated
by SD systems,
which belong to the third design type described above [5].
In general, meteorological, operational and demand side
conditions are critical

Table 1
Costs of the conventional power supply systems in the island of
Crete
Alternative power supply Investment( /kW) Operating costs
systems
Fuel cost O&M variable O&M fixed
( /kWh) ( /kWh) ( /kW/year)
Gas turbines – 0.118 1.76 26.41
Diesel engines 34.37 0.026 1.17 22.01
Steam units 79.85 0.036 2.05 24.95
GT to CC conversion 50.03 0.079 1.46 17.61
Source: [1].
875T. Tsoutsos et al. / Renewable Energy 28 (2003) 873–886
when comparing the alternative solar power systems directly
[6]. The comparison
shows that each technology has its strengths and weaknesses,
and a final decision
on the implementation of a particular project can only be taken
by considering the
special circumstances at each site [7]. Moreover each
technology has advanced vari-
ants with different performance and costs [8]. In order to get an
overview, a decision
maker is forced to consult specialists on each technology.
2.2. Solar Stirling engines
Engine designs for SD applications are usually categorized as

either kinematic or
free-piston.
� Kinematic Stirling engines: both the power piston and the
displacer (or the com-
pression and the expansion pistons) are mechanically
(kinematically) linked to a
rotating power output shaft.
� Free-piston Stirling engine: they have only two moving parts,
the displacer and
the power piston, which travel back and forth between springs.
A linear alternator
is incorporated into the power piston to extract power from the
engine. As elec-
tricity is generated internally, there is no sliding seal at the
high-pressure region
of the engine therefore no oil lubrication is required. These
designs promise long
lifetimes with minimal maintenance requirements.
The technical challenges of the kinematic Stirling engine are
sealing problems and
complicated power modulation. Sealing problems can be
avoided if a rotating alter-
nator is integrated in the crankcase. The power modulation
problem can be solved:
(a) by varying the pressure level of the working space; and (b)
by varying the piston
stroke. The second power modulation method requires a
mechanism to vary the
piston stroke, a so-called swash plate. Varying the angle
between the swash plate
and the outgoing axis of the engine varies the piston stroke.
Each of these power
modulation methods results in a complex engine design, which

includes a large num-
ber of critical mechanical parts [9,10].
Free-piston Stirling engines have the advantages of kineatic
Stirling engine, but
avoid the technical problems. It can be hermetically sealed,
eliminating the need for
a working fluid make-up system typical of a kinematic Stirling
engines. In addition
there is no connection between the power piston and the
displacer piston. Both the
phase angle between them and the stroke of the power piston are
therefore variable
and the power developed by the engine depends on both. This
means that, in principle
at least, the power of the engine could be controlled without
having to change the
pressure. Therefore, free-piston Stirling engines have simple
design [11].
The only disadvantage of the SD system is its cost. However,
this cost is less
than the cost of a photovoltaic unit and comparable to the cost
of parabolic trough
systems, which is used commercially in California.
Furthermore, the combination of
technical improvements and mass production could reduce this
cost by over 50% [7].
2.3. The Stirling engine and the environment
The Stirling engine is an environmentally very clean engine,

because, when the
heat comes from solar energy, the polluting emissions are
almost zero. When the
heat comes from hydrocarbon (HC) combustion, the emissions
are also very low,
because the fuel is burnt continuously and at near atmospheric
pressure, in remark-
able contrast to the interrupted, explosive combustion in petrol
and diesel engines
with relatively cold walls.
The combustion of fuel in a Stirling engine takes place in a
space surrounded by
hot walls, under adiabatic conditions. Because of this and
because of the latitude in
the choice of the air-to-fuel ratio the quantities of the CO
produced and of the unburnt
HCs are very low. Unfortunately, the more efficient combustion
of a Stirling engine
results in proportionately more CO2 being produced than with
an equivalent internal
engine. However, the CO2 is one of the most important
contributors to the greenhouse
effect. Therefore, if the Stirling is to maintain its position as an
environmentally
friendly engine, then some techniques for removing the exhaust
CO2 must be used.
The preheating of combustion air leads to a high flame
temperature (~2000°C),
which favors the formation of NOx, yet these emissions are
lower than expected.
This is due to relatively short residence time of the gases at the
high temperature,
lower peak temperatures than in the internal combustion engine
and the continuous

combustion. The production of NOx can be reduced more: (a) by
recirculating part
of the flue gasses along with the incoming combustion air; and
(b) by lowering the
flame temperature. The Stirling cycle is not effected
detrimentally due to the external
heating of the engine.
Regarding the emission of toxic or other polluting substances,
the Stirling engine
is inherently cleaner than all other current heat engines [11].
2.4. Description of the SD solar electric generating system
The SD electric systems, providing net solar-to-electric
conversion efficiencies
reaching 30%, can operate as stand-alone units in remote
locations or can be linked
together in groups to provide utility-scale power [12].
Individual units range in size from 10–25 kW. They consist of a
solar concentrator,
and a power conversion unit located at the focal point of the
dish. The unit consists
of a cavity receiver and a Stirling heat engine with an electric
generator or alternator.
The concentrator reflects and concentrates solar radiation,
which is then delivered
to the receiver. The receiver absorbs concentrated sunlight,
transferring its heat
energy to a working fluid, in the Stirling engine. The working
gas (typically H2 or
He) is alternately heated and cooled. The engine works by
compressing the working
gas when it is cool and expanding it when it is hot. Expanding
the hot gas that is

required to compress the cool gas produces more power. This
action produces a
rising and falling pressure on the engine’ s piston, the motion of
which is converted
into mechanical power. An electric generator or an alternator
converts the mechanical
power into electricity [13].
Solar SD engines have advantages over more conventional
power generation
options because they:
� produce zero emissions when operating on solar energy;
� operate more quietly than diesel or gasoline engines;
� are easier to operate and maintain than conventional engines;
� start up and shut down automatically; and
� operate for long periods with minimal maintenance.
Solar concentrators used for SD applications are generally
point-focus parabolic
dish concentrators. Because of the parabolic shape, the dishes
have concentrations
ratios ranging from 600–2000 and they can achieve
temperatures in excess of
1500°C.
The size of the solar collector for SD systems is determined by
the power output
desired at maximum insolation levels (1000 W/m2) and the
collector and power-
conversion efficiencies. With current technologies, a 5 kW SD
system requires a dish

of ca 5.5 m, in diameter, and a 25 kW system requires a dish ca
10 m in diameter.
Concentrators can typically account for ca 25% of the cost of a
SD system. Con-
centrating reflectors can be divided in three categories as
follows.
� Glass-faceted concentrators use spherically curved
individually align glass mirror
facets, mounted on an approximate parabolic-shaped structure.
� Full-surface parabolic concentrators: the entire surface forms
an approximately
parabolic shape.
� Stretched-membrane concentrators: can be a single-facet or
multifaceted. The
designs incorporating thin membranes stretched over both sides
of a metal ring.
The membranes may be thin plastic sheeting or thin metal
sheeting with a reflec-
tive coating applied to one of the membranes.
Tracking the sun’ s path increases the efficiency of the
concentrator. There are two
ways of implementing this:
� Azimuth-elevation tracking: in which the dish rotates in a
plane parallel to the
earth (azimuth) and in another plane perpendicular to it.
� Polar tracking method: in which the collector rotates about an
axis parallel to the
earth’ s axis of rotation and about the declination axis which is
perpendicular to

the polar axis.
3. Characteristics of the solar power plant
The design characteristics of a typical system (solar electricity
system SD 25 kW)
are shown in Table 2 [14].
Important performance advantages of the SD are its ability to
operate earlier and
later each day and it can also operate on cloudy days when solar
energy is �2
kWh/m2. In addition, due to its low thermal inertia, it can
generate power between
passing clouds as a photovoltaic unit can. Central receiver and
parabolic trough
require 1–2 h of steady insolation between clouds for successful
start-ups. During
Table 2
Design characteristics of a solar electricity system SD 25 kW
Concentrator
Glass area 91.01 m2
Aperture area 87.67 m2
Focal length 7.45 m
Glass type No. 82 Commercial grade float. Thickness: 0.7
mm
Radius of curvature 599, 616, 667, 698”

Waviness �0.6 mr
Reflectivity �90%
Module dimensions 11.89 mH, 11.28 W
Module weight 6.934 kg
Stirling engine (kinematic)
Engine dry weight 225 kg
Displacement 380 cc
Engine dimensions 66 cm W, 71 cm H, 58cm L
Number of pistons 4. double acting
Working fluid H2 or He
Working fluid pressure 20 MPa
Operating temperature 720°C
Power control Fluid pressure
Cooling Water/forced air fan
Output power 27 kW (max), 22 kW (rated)
Rated power efficiency 38–40%
Power conversion unit
Weight �680 kg
Alternator Induction, 1800 rpm
Alternator efficiency 92–94%
Electrical power 480 V, 60 Hz, three phase
Gross power rating 25 kW at 1.000W/m2
Peak net power efficiency 29–30%
Minimum insolation 250–300 W/m2
Dimensions W=168 cm, H=122 cm, L=183 cm
Source: [10].
frequent cloud passes for such systems the start up efforts
consume more power
would then be generated [15] (Figs. 1 and 2).
The size of the solar power plant for this analysis is 50 MW and
it’ s going to be

located at a region with high solar radiation and low cost of
land. The location of
the solar thermal power plant for this study will be in southeast
side of Crete (Lasithi)
(Table 3), where the average annual solar radiation is high
(1.728 kWh/m2) and land
cost is low (23.5–29.0 k /ha).
4. Cost estimation
The selected economic indicators are: the net present value
(NPV) and electricity
generation cost.
Fig. 1. Stirling Energy Systems, Inc. (SES)/Boeing, 25 kW SD
system at sunset. Source: [15].
NPV � (E�O)
1�(1 � i)�N
i
�CC,
where E is the annual income, O is the annual operating and
maintenance cost, i is
the discount rate and CC is the capital cost.
Electricity generation cost �
NPV
Total electricity production
.

The energy inflation is considered negligible.
NPV and electricity generation cost are estimated for two
different annual pro-
duction levels of 10 000 and 2000 SD systems (Tables 4 and 5).
Other issues, such
as siting as well as the optimal solar power plant size, were not
covered by the
current analysis.
A series of sensitivity analyses is undertaken in order to
investigate the magnitude
of the effect of the parameters variation on cost calculation. The
parameters are:
Fig. 2. McDonnell Douglas (currently Boeing) SD system.
Source: [15].
Table 3
Weather conditions in Crete
Iraklio Ierapetra Rethimno Chania
Annual solar radiation (kWh/m2) 1785.4 1728.0 1739.9 1700.6
(slope 0°)
Annual sunlight (h/year) 2816 3108 2694 2809
Average temperature per year (°C) 19.0 20.0 19.6 18.5
Source: [3].
� system capital purchase price;

� discount rate;
� annual solar radiation;
� lifetime;
� annual efficiency of the system;
� market price of the electricity; and
� size of the power plant.
5. Discussion and conclusions
The technology system, which was described, is a considerable
alternative to deal
with the energy problems of the island of Crete. It is also
essential the timing of
Table 4
Assumptions and data
Annual production rate of SD systems 10 000 2000
Technical data
Number of units 25 25
Total power (MW) 50 50
Annual solar radiation (kWh/m2) 1.728 1.728
Annual generated electric energy (MWh) 69.711 69.711
Discount rate 10% 10%
Lifetime (years) 30 30
Sale price of electricity ( /kWh) 0.073 0.073
System purchase price ( /kW) 555a 1.611a
Fixed cost
Procurement of equipment (M ) 22.40 64.89
Transport & installation (M ) 3.36 9.73

Land purchase (M ) 1.90 1.90
Earthworks etc (M ) 2.20 9.96
Other costs (M ) 7.46 2.16
O&M
Labor cost (k ) 2.2 2.2
Consumables (M ) 1.01 1.01
a [8].
Table 5
Results
Annual production rate of SD systems 10 000 2000
Electricity generation cost ( /kWh) 0.071 0.178
Net present value (k ) 1.380 �69.479
the high demand (midday, summer) and the high insolation
offering a solution during
the summer period.
Furthermore the substitution of an imported liquid fuel, the
avoidance of the CO2
emissions, the creation of new jobs and the improvement of the
living standard are
essential benefits.
According to the results of the above analysis only the massive
production of
solar Stirling systems could provide a long-term economical
feasible solution. The
technical and economic evaluation shows that the SD
technology offers a technical
feasible and economic viable solution under the following
conditions (Table 6):

� system purchase price �550 /kW;
� discount rates �10%;
� long lifetime (�25 years);
� solar radiation �1700 kWh/m2;
Table 6
Sensitivity analysis
Scenario
Scenario 1: Variation of system purchase price
Power of plant 50 50 50 50 50
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
Annual generated 69711 69711 69711 69711 69711
electricity (MWh)
Discount rate (%) 10 10 10 10 10
Lifetime (years) 30 30 30 30 30
Electricity sale 0.073 0.073 0.073 0.073 0.073
price ( /kWh)
System purchase 440 550 660 770 880
price ( /kW)
Results
Capital cost 29.84 37.29 40.69 47.47 54.25
(million )
Operating and 1.012 1.012 1.012 1.012 1.012
maintenance cost
(million )
Electricity 0.060 0.071 0.076 0.087 0.097
generation cost

( /kWr)
Net present value 8.84 1.38 �2.01 �8.79 �15.57
(million )
Scenario 2: Variation of discount rate
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
electricity (MWh)
Discount rate (%) 8 10 12 14 16
price ( /kWh)
price ( /kW)
Results
Capital cost 37.29 37.29 37.29 37.29 37.29
(million )
Operating and 1.012 1.012 1.012 1.012 1.012
maintenance cost
(million )
Electricity 0.062 0.071 0.081 0.091 0.101
generation cost
( /kWr)
Net present value 8.89 1.38 �4.24 �8.57 �11.95
(million )
(continued on next page)
Table 6 (continued)

Scenario
Scenario 3: Variation of lifetime
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
electricity (MWh)
Discount rate (%) 10 10 10 10 10
price ( /kWh)
price ( /kW)
Results
Capital cost 37.29 37.29 37.29 37.29 37.29
(million )
Operating and 1.012 1.012 1.012 1.012 1.012
maintenance cost
(million )
Electricity 0.074 0.071 0.070 0.069 0.069
generation cost
( /kWr)
Net present value �0.434 1.380 2.404 2.982 3.309
(million )
Scenario 4: Variation of annual solar radiation
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
electricity (MWh)

Discount rate (%) 10 10 10 10 10
price ( /kWh)
price ( /kW)
Results
Capital cost 37.29 37.29 37.29 37.29 37.29
(million )
Operating and 1.012 1.012 1.012 1.012 1.012
maintenance cost
(million )
Electricity 0.089 0.071 0.059 0.051 0.045
generation cost
( /kWr)
(million )
Table 6 (continued)
Scenario
Scenario 5: Variation of annual efficiency of the system
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
Annual generated 55769 69711 83653 97595 1.12E+08
electricity (MWh)
Discount rate (%) 10 10 10 10 10

price ( /kWh)
price ( /kW)
Results
Capital cost 37.29 37.29 37.29 37.29 37.29
(million )
Operating and 1.012 1.012 1.012 1.012 1.012
maintenance cost
(million )
Electricity 0.091 0.089 0.071 0.059 0.051
generation cost
( /kWr)
(million )
Scenario 6: Variation of the electricity sale price
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
electricity (MWh)
Discount rate (%) 10 10 10 10 10
price ( /kWh)
price ( /kW)
Results
Capital cost 37.29 37.29 37.29 37.29 37.29
(million )
Operating and 1.012 1.012 1.012 1.012 1.012
maintenance cost
(million )
Electricity 0.071 0.071 0.071 0.071 0.071

generation cost
( /kWr)
(million )
Table 6 (continued)
Scenario
Scenario 7: Variation of the plant size
(MW)
Annual solar 1728 1728 1728 1728 1728
radiation
(kWh/m2)
electricity (MWh)
Discount rate (%) 10 10 10 10 12
price ( /kWh)
price ( /kW)
Results
Capital cost 29.84 37.29 44.75 52.21 59.67
(million )
Operating and 0.810 1.011 1.213 1.416 1.618
maintenance cost
(million )
Electricity 0.071 0.071 0.071 0.071 0.071
generation cost
( /kWr)

Net present value 1.121 1.401 1.681 1.961 2.242
(million )
� annual generated electricity � 69.711 MWh;
� electricity sale price �0.073 /kWh.
When the annual rate production of SD systems is low, the
establishment of a SD
solar power plant is worthwhile on many islands of Greece,
which high cost of
conventional electricity generation (0.18–0.29 /kWh). The
installation of a solar
power plant in Crete is worthwhile only for high production rate
of systems. The
hybrid solar/fossil-fuel operation makes the system competitive
with conventional
fossil-fueled power plants in cost terms.
If externalities are included in cost estimation, the cost of
electricity will be almost
the same for both conventional and solar power generation.
Therefore, if external
costs are reflected in taxes, the SD system will be commercial.
In long-term period, solar thermal power stations based on a SD
can become a
competitive option on the electricity market, if a concerted
programme capable of
building the forces of industry, finance, insurance and other
decision makers will
support the market extension of this promising technology.

Acknowledgments
The authors would like to acknowledge DOE/NREL and credit
Stirling Energy
Systems, as well as McDonnell Douglas (currently Boeing) for
the figures.
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Technical and economical evaluation of solar thermal power

generationIntroductionSolar Stirling enginesSolar thermal
electric technologySolar Stirling enginesThe Stirling engine and
the environmentDescription of the SD solar electric generating
systemCharacteristics of the solar power plantCost
estimationDiscussion and
conclusionsAcknowledgmentsReferences
Energy Conversion and Management 51 (2010) 1621–1628
Contents lists available at ScienceDirect
Energy Conversion and Management
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c
a t e / e n c o n m a n
Economical investigation of an integrated boiler–solar energy
saving system in Jordan
A. Al-Salaymeh a,*, I. Al-Rawabdeh b, S. Emran c,1
a Mechanical Engineering Department, Faculty of Engineering
and Technology, University of Jordan, Amman 11942, Jordan
b Industrial Engineering Department, Faculty of Engineering
and Technology, University of Jordan, Amman 11942, Jordan
c Euro Boilers Company, Middle East Est. For Heating
Equipment Trade & Industry, P.O. Box 310038, Amman 11131,
Jordan
a r t i c l e i n f o a b s t r a c t
Article history:
Available online 6 January 2010
Keywords:
Solar energy
Energy saving system

Space heating system
0196-8904/$ - see front matter � 2009 Elsevier Ltd. A
doi:10.1016/j.enconman.2009.08.040
* Corresponding author. Tel.: +962 6 53 55 000x27
E-mail addresses: [email protected] (A. Al-Salay
Al-Rawabdeh), [email protected] (S. Emran).
1 Tel.: +962 6 4894586; fax: +962 6 4888049.
Jordan is relatively poor in conventional energy resources and is
basically a non-oil producing country, i.e.
its energy supply relies to a very large extent on imports. It is
therefore unlikely that any future energy
scenario for Jordan will not include a significant proportion of
its energy to come from renewable sources
such as solar energy. The lack of an integrated energy saving
system which utilizes the solar energy for
domestic hot water as well as for building space heating was the
main motivation for the present study.
In Jordan, there is no existing system can provide the
integration mechanisms of solar energy and fuel
combustion with electrical ones. Also adding new and related
products increases sales of current boilers
products and can be offered at competitive prices.
During our investigations, it has been found that the market
demand for boiler–solar integration sys-
tem in terms of the system acceptability, system feasibility, and
system values is very high especially
after the increased in oil prices during the last 3 years, i.e.
2006–2008. The market trend shows that even
though solar collector is not attractive as an energy source for
domestic hot water, but the combined sys-
tem for space heating and domestic hot water is fully accepted.
However, the market demand for such a
system is not completely identified yet but the awareness and

the discussion of the idea shows a good
potential.
The economical study about the integration system of boiler and
solar energy shows that using solar
water heaters to heat space and for domestic water is cost-
effective. Payback can be as low as 3 years,
and utility bills are much lower than they would be using a
conventional heating system. The initial draft
and design of a prototype for the boiler–solar–electrical
integration system has been carried out.
� 2009 Elsevier Ltd. All rights reserved.
1. Introduction coming 5 years, e.g. Al-Salaymeh [2]. The
Jordanian authority and
One of the most important energy sources in our economy is
still oil, which is not renewable considering our lifetime. Jordan
is an energy importing country; about 96% of its energy needs
sup-
plied from abroad as crude oil and refined products. Hrayshat
and
Al-Soud [1] pointed out that the share of solar energy in the
total
energy mix in Jordan is estimated to be around 1.7% during the
year 2002. They also showed that the expected share of solar
en-
ergy in the total energy mix in the year 2007 is estimated to be
around 2.1%. During the Renewable Energy International
Confer-
ence which was held in Bonn, Germany during 1–4 June 2004,
Jor-
danian authority has been committed to have 5% of its total
energy
requirements from renewable energy resources for the next
ll rights reserved.

88; fax: +962 6 53 555 88.
meh), [email protected] (I.
especially the ministry of Energy are working currently to have
7% of the total energy requirements in Jordan to be from
renewable
energy resources in 2015 and 10% in 2020. The share of
renewable
energy in the primary energy supply of the southern Mediterra-
nean countries has been relatively low and varies from a
minimum
of 0.6% in Tunisia to a maximum of 19% in Palestine. This
share can
reach 2.0% in Algeria, 2.8% in Lebanon, 4.4% in Egypt, and
6.5% in
Syria.
In fact, Jordan is blessed with huge amounts of renewable en-
ergy resources, particularly solar energy. In order to reduce
depen-
dence on the imported oil, Jordan has pursued programs for
promoting solar energy involving systematic monitoring and
assessment of technological developments combined with the
implementation of appropriate technologies, demonstrations and
pilot projects [3–7]. The current tendency in Jordan is to use in
fu-
ture various solar energy applications in the over all mix of
energy
in Jordan, as well as identifying potential areas for utilizing
future
technologies and recommending future courses of action to
encourage the commercial utilization of solar energy
technologies.
http://dx.doi.org/10.1016/j.enconman.2009.08.040
mailto:[email protected]

http://www.sciencedirect.com/science/journal/01968904
http://www.elsevier.com/locate/enconman
1622 A. Al-Salaymeh et al. / Energy Conversion and
Management 51 (2010) 1621–1628
As we know, all sources of energy may be grouped into two
gen-
eral categories; income energy, which is the energy reaching the
earth from outer space such as solar energy, and capital energy,
which is the energy that already exists on or within the earth
such
as fossil fuels, e.g. [8]. The hot Sun gives light and life and it is
an
inexhaustible supply of pollution-free power. The ancient
Egyptian
Pharaohs solar heated their palaces by capturing solar energy in
black pools of water by day and draining the hot water into
pipes
in the floor of the palaces at night. Affluent ancient Greeks de-
signed their homes orientated to the sun to use winter sunlight
for heating. Large south-facing windows were used to collect
solar
heat, which was stored in massive walls and floors for gradual
re-
lease throughout the night. Solar energy put to full use would
help
to give the world energy independence, minimizing dangerous
pol-
lution levels and our dependence on fossil fuels. Therefore,
solar
energy can be considered as the most abundant continuing
source
of energy available to the human race.

One of the promising usages of renewable energy technology is
the installation of the solar collector system, which has already
demonstrated its effectiveness and holds great promise for hot
water generation. The applications of the solar collector system
have become more widespread in both developed and
developing
countries [9,10]. Due to high and reliable solar irradiance of
about
5.5 kW h/m2 day a domestic usage for solar energy in Jordan
over
the life time has the potential to produce a domestic hot water
in addition to the heating and cooling of buildings for about
330 sunny days per year using solar collectors [11]. Solar
irradi-
ance varies with season and time of the day due to the various
Sun positions under the unpredictable weather conditions [12].
Conventionally, different mathematical models have been devel-
oped in Europe to predict the solar irradiance on various in-
clined-surfaces using horizontal data [13,14]. Data on average
hours of sunshine or average percentage of possible sunshine
hours are widely available from stations in many countries, e.g.
[15]. Al-Salaymeh [2] developed a mathematical model for the
pre-
diction of global daily solar radiation on horizontal surfaces for
Amman city in Jordan.
2. Aim of the work
The price of oil is increasing and the energy bill is very expen-
sive for Jordan. As it is known, Jordan is imported oil from
neigh-
boring countries and this oil costs too much. Currently, a local
study on renewable energy reported that solar technologies are
potentially suitable for wide scale applications in Jordan. These
re-
sults show that Jordan need to begin to rely more on solar
energy

in order to reduce the dependence on imported expensive
sources
of energy. The energy demand, in Jordan, was doubled during
the
last 20 years, and expected to continue at the same rate. Hence,
all recent energy forecast scenarios showed that the national
con-
sumption might double between 2015 and 2020. Due to
increasing
oil prices, the financial aspect of this problem has increased and
its
resultant outcomes are clearly observable these days in Jordan.
Utilizing of solar energy with boiler systems for domestic hot
water as well as for building space heating can save energy and
therefore can reduce the energy cost for domestic uses. The idea
shows that a significant market segment is willing to invest in
this
system mainly to the expected increase in the fuel cost. The
market
trend shows that even though solar collector is not attractive as
an
energy source for domestic hot water, the idea of the integration
is
fully accepted and it needs to be tested on real cases.
The present investigation aims to develop a new energy saving
system that integrates solar, boiler, and electrical systems for
heat-
ing purposes. The draft of the initial features and characteristics
of
the system is shown in Fig. 1. The system pilot testing includes
offering the idea of the system to a sample group of customers
to
determine if these customers need the system and are willing to
buy it, identifying if there is a demand for the new system,

whether
modifications or changes to the terms and conditions will make
the
system more appealing, and what features or processes need
adjustment, and calculating the cost and price of the system.
The
proposed methodology based on the economical study about the
integration system of boiler and solar energy.
3. Theoretical background
Energy is one of the most important factors in wealth genera-
tion, economic growth and social developments of the present
countries. Based on historical data, one can observe that there is
a strong relationship between the development of economic
activ-
ities and availability of energy resources, i.e. energy is of vital
importance all over the world for the process of production and
manufacturing, and as such, a key element of sustainable
develop-
ment of countries.
Referring to the measurements on radiation as well as to the
variation in the topography and climatology of Jordan, the
country
is divided into five regions [16–18].
1. The southern region (29–30.5 �N, 35–38 �E): in this region,
the annual daily average values of global irradiance are
between 6 and 7 kW h/m2 day.
2. The eastern region (30.5–32.5 �N, 36.5–39 �E): in this
region,
the annual daily average values for global of about 5.0 kW h/
m2.
3. The middle region (30.5–32 �N, 35.5–36.5 �E): in this

region,
the global irradiance is about 4.5 kW h/m2 day in this region.
4. The northern region (32–33 �N, 35.5–36.5 �E): in this
region
the annual daily average value of global irradiance is about
5.5 kW h/m2 day.
5. The western region (30.5–33 �N, 35–35.5 �E): in this
region,
the annual daily average values of global irradiance are
between 4.5 and 5 kW h/m2 day.
In general, the abundance of solar energy in Jordan is evident
from the annual daily average of global solar irradiance, which
ranges between 5 and 7 kW h/m2 day on horizontal surfaces.
This
corresponds to a total annual value of 1600–2300 kW h/m2
year.
The measurements data that including horizontal solar
irradiance
and sunshine duration of solar irradiance for Amman city
(latitude
of 32�10N) has been taken. Al-Salaymeh [2] predicated global
solar
radiation data on a horizontal surface for Amman city as shown
in
Fig. 2. The scatter in the data shown in Fig. 2 is due to low
number
of years that is used in the calculation (only 3 years).
Different correlation formulas for global solar radiation for Am-
man city that used the Sine wave correlation formula with con-
stant Y-value, Lorentzian correlation formula, Gaussian
correlation formula and the 4th order polynomial degree are
shown also in Fig. 2, e.g. Al-Salaymeh [2]. The mean value of

energy
of quasiglobal radiation for Amman equals 5324 kW h/m2 day.
Jor-
dan receives the most solar energy in June (mean value 7995
kW h/
m2) and the least in December (mean value 2676 kW h/m2).
Fig. 3 shows the meteorological data for sunshine duration in
Amman which acquired from observed mean values on meteoro-
logical stations for 3 years. The scattering in the data is very
high
because the number of years used to calculate the average sun-
shine duration is only 3 years. The maximum value of sunshine
duration in Amman occurs in June and July (mean value is
11.86 h for June and 12.05 h for July) and the least in December
(mean value 5.14 h), e.g. Al-Salaymeh (2006).
Solar collector
Boiler Electrical heater
Hot Water
Temperature Heating load
Computer aided
controller (PLC-
Based)
Water Feed Rate
Ambient
Temperature

Heating Capacity
Heating Capacity
Solar Intensity
Fig. 1. The initial features and characteristics of the boiler–
solar–electrical integration system.
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
Fe
br
ua
ry
Month

G
lo
ba
l S
ol
ar
R
ad
ia
tio
n
[k
W
.h
r/
m
2d
ay
] Sine wave
Lorentzin
Gaussian
4th order Polynomial
actual data
Actual
data

Lorentzin
4th ordr
polynomial
Gaussian
Sine
wave
Ja
nu
ar
y
M
ar
ch
Ap
ril
M
ay
Ju
ne
Ju
ly
Au
gu

st
Se
pt
em
be
r
O
ct
ob
er
No
ve
m
be
r
De
ce
m
be
r
Fig. 2. Global daily solar radiation data with different suggested
prediction models in Amman, Jordan as a function of time.
0

2
4
6
8
10
12
14
Ja
nu
ar
y
Ja
nu
ar
y
M
ar
ch
Ap
ril
M

ay
M
ay
Ju
ne
Ju
ly
Au
gu
st
Se
pt
em
be
r
O
ct
ob
er
No
ve
m
be

r
De
ce
m
be
r
Month
S
un
sh
in
e
D
ur
at
io
n
(h
r)
Amman City
Fig. 3. Measured average sunshine duration data in Amman,
Jordan by days.
A. Al-Salaymeh et al. / Energy Conversion and Management 51

(2010) 1621–1628 1623
Management 51 (2010) 1621–1628
3.1. Collector thermal performance
The thermal performance of a solar collector is determined by
establishing an efficiency curve from the instantaneous
efficiencies
obtained using a combination of values of incident solar
radiation,
ambient temperature, and inlet fluid temperature. Measurements
should be made for the fluid flow rate, the temperature of the
fluid
at the inlet and outlet, the incident solar radiation, the ambient
temperature, and the wind speed.
g ¼
Useful Energy Collected
Incident Solar Energy
¼
Q u
I A
ð1Þ
where Q u ¼ _m CpðT o � T iÞ, _m is the mass flow rate, Cp is
the specific
heat, To is the temperature of the fluid leaving collector, Ti is
the
temperature of the fluid entering collector, I is the incident
solar en-

ergy per unit area and A is the area of the collector.
Due to the inevitable changes in solar irradiance and to exclude
time dependencies, integration and averaging over a period of
measurements is required. Eq. (1) can be rewritten as:
g ¼
R t2
t1
m � cp � ðT o � T iÞ � dt
A �
R t2
t1
I � dt
ð2Þ
The percentage of energy saving in the case of a combined so-
lar–boiler energy saving system can be calculated as the
following:
% of saved energy ¼
heat gained from collector
boiler input energy
ð3Þ
The calculation of the amount of fuel consumption in each
month by using the conventional boiler system for space heating
has been carried out by using the degree day method, e.g.
Hammad
and AlSaad [19].

4. Design of energy saving system
Solar energy is a renewable resource that is environmentally
friendly and it can be used in many ways for water heating and
space heating in buildings. The integrated system will reduce
the
need for conventional water heating for domestic usage as well
as for space heating, minimizing the expense of electricity or
fossil
fuel to heat the water and reducing the associated environmental
impacts.
By using passive solar systems or active solar systems or a com-
bination of both, solar energy can help heat or cool buildings.
Incorporating passive solar designs can reduce heating bills by
as
much as 50%, e.g. [20]. In the space heating, it is recommended
to use flat-plate collectors which can heat the water temperature
till 80 �C. Also, evacuated-tube or heat-pipe collectors can be
used
to obtain a high water temperature and a high efficiency
especially
in the winter season. Currently, evacuated-tube collectors are
proved to be more efficient than flat-plate solar collectors
because
the efficiency of flat-plate solar collector decreases as the
ambient
temperature decrease and it might be to reach zero at cold
condi-
tions. The evacuated-tubes collectors have a high value of effi-
ciency and it can save more than 90% from the heating energy
bill.
Using solar water heaters to heat building is cost-effective. Of
course, inside buildings generally will have a conventional
heater

or boiler as back-up. When the space needs heating, water is di-
verted to the collectors, where it is warmed and returned to the
building.
The solar integrated system is a solar thermal system that can
provide domestic water heating and space heating. It includes
mul-
ti series collectors, and a large solar storage system. A heat
exchan-
ger is needed to transfer solar energy to preheat domestic hot
water and to provide space heating. The system is ideally suited
to allow solar heating of radiant floor systems. Of course, there
is
still a requirement for a back-up heating system. Boilers are
fuel-
burning appliances that produce hot water that gets circulated
through piping for heating uses.
A schematic diagram for the main components of the integrated
energy saving system with boiler, electrical heater, solar
collector
and storage tanks are shown in Fig. 4.
In the present work, the schematic diagram for the designed cy-
cle of the integrated energy saving system with boiler, electrical
heater, solar collector, DHW, control board, digital temperature
monitor, expansion tank, check and pressure relief valves, and
pressure gauge, and storage tank with internal heat exchangers
are shown in Fig. 5. The designed system consists of three
loops,
namely: the collector loop, the space heating load loop, and the
domestic hot water loop.
The collector loop consists of collectors (3), storage tank (7),
cir-
culating pump (1), and other subsidiary components. The space

heating loop includes the storage tank (7), the expansion tank
(10), the load devices (under-floor heaters or fan coil units),
and
the back-up system (11). The system is equipped with a flow
con-
trol valve (4) and other supplementary components. The hot
water
loop includes: a storage tank (8), a heat exchanger immersed in
the
storage tank and a circulating pumps (1).
The liquid storage tank is best to be spherical to minimize heat
losses and tank material requirements. However, spherical tanks
are difficult to fabricate, consume a volume in the building
which
is about twice of its volume, and require special supports. A
com-
promise shape, easier to fabricate is a right circular cylinder
with a
height equal to its diameter. The surface area of such a tank is
only
about 15% greater than of a sphere, such a tank designed
according
to our requirement. The storage tank used for heat storage is of
the
cylindrical type (1500 L capacity).
Many differential temperature controls monitor the tempera-
tures at the collector outlet and at the solar storage tank. When
the collectors are hotter than the tank, the control turns on a
circu-
lator which circulates the fluid through the collectors and back
to
the heat exchanger. Heat is stored in the storage tank until it is
called for. When there is draw on the domestic water system,
cold

water flows through a heat exchanger in the storage tank and
out
to an auxiliary water heater and then to the point of use. As the
water is passed through the heat exchanger, it is heated to the
tem-
perature of the storage tank. If the water has not reached
delivery
temperature by the time it enters the auxiliary heater, this heater
will turn on and provide supplementary heat, e.g. [21]. The
most
important control element in the integrated boiler–solar system
is the temperature differential controller to control the operation
of pumps. If the temperature sensed by a thermistor connected
to the absorber plate of the solar collector, exceeds the tempera-
ture in the bottom of the storage tank by a certain value (usually
5 �C), the collector pump will be activated and will continue to
run until the collector and storage temperature are within 1–2
�C
of each other. At this point the pump will be turned off. This
con-
troller is also used to protect the solar collector from freezing.
These collectors are the type being designed and manufactured
by the RSS, e.g. [21]. Solar water heating is most effective
when it
can provide hot water under coldest conditions, i.e. winter. The
col-
lectors should be oriented to the south with a winter operation
tilt
angle of approximately 45� (13� greater than the local
latitude).
Piping layout should be arranged in a way that the hot water
outlet
piping is shorter than the supply piping to minimize heat losses.
5. Results and discussions

Selecting a building’s comfort system represents a complex
tradeoff between numbers of different perspectives. Architects,
engineers, contractors, building owners and developers have
many
Fig. 4. A schematic diagram of the integrated solar energy
saving system with boiler, electrical heater, solar collector and
storage tank.
Fig. 5. A schematic diagram of the designed integrated solar
energy saving system with boiler, electrical heater, solar
collector and storage tank.
(2010) 1621–1628 1625
things to consider. While the heating system may represent only
10% of the building’s total cost, poor decisions in system
design
made today can result in significant problems for building occu-
pants and owners tomorrow.
The integrated boiler–solar system uses solar energy to sub-
stantially reduce energy costs. This system effectively provides
en-
ergy nearly free cost using the solar energy during cold and hot
weather without the requirement to run a boiler. The boiler is
essentially shut off during this period, thereby saving energy
and
also allowing scheduled preventative maintenance to take place.
The boiler can be shut down form 7 to as may as 9 months a
year.
Solar energy can be used to save energy whenever the outside
condition is sunny. This energy-efficiency measure can save en-

ough boiler power to pay for solar collectors and storage tanks
installation costs in less than 3 years. The payback period for
the
solar energy system is different in each case. The more hot
water
you use, for example with more people in the house, the more
you will save by having a solar system. Also if you use more
hot
0
50
100
150
200
250
Ja
nu
ar
y
Fe
br
ua
ry
M

ar
ch
A
pr
il
M
ay
Ju
ne
Ju
ly
A
ug
us
t
Se
pt
em
be
r
O
ct
ob
er

N
ov
em
be
r
D
ec
em
be
r
Month
Fu
el
C
os
t (
$
U
S
)
Space Heating (Boiler only)
Domestic Hot Water (Boiler only)

Fig. 7. Energy cost of the fuel consumption for space heating
and domestic hot
water at different months around the year in the case of the
boiler system only.
0
40
80
120
160
200
Fu
el
C
os
t (
$
U
S
)
Space Heating (Integrated System)
Domestic Hot Water (Integrated System)

Ja
nu
ar
y
Fe
br
ua
ry
M
ar
ch
A
pr
il
M
ay
Ju
ne
Ju
ly
A
ug
us
t

Se
pt
em
be
r
O
ct
ob
er
N
ov
em
be
r
D
ec
em
be
r
Month
Fig. 8. Energy cost of the fuel consumption for space heating
and domestic hot
water at different months in the case of the integrated combined
system.

Management 51 (2010) 1621–1628
water in sunny weather the more you will save, because that’s
when free hot water is available. The other factor is the cost of
existing fuel, which may range from an efficient condensing gas
boiler to an electric immersion heater.
In order to study the economic effect of using the integrated
boiler–solar system on the cost of the operating of boiler in the
domestic hot water and space heating, a case study has been
car-
ried out for small flat which has approximately 200 m2.
Most people make a purchase to solve a real or perceived prob-
lem. They use economic evaluations to justify their decision. A
number of factors influence the costs of owning and operating
an
integrated solar–boiler energy saving system. These include:
Installation cost, operating costs (including all the fuel and
electric
costs to accommodate one alternative over others) and mainte-
nance costs.
Fig. 6 shows the average values of the minimum and maximum
temperatures for each month in the year at the location of Euro
Company in Marka which is located between Amman and Zarka
cities, e.g. Al-Salaymeh et al. [22]. It is clear from Fig. 6 shows
that
we can get benefits from the solar energy for space heating at
many months in the year. The space heating can be used in the
case, where the ambient temperature is below 19 or 20 �C.
In order to calculate the thermal performance of a solar collec-
tor, we assumed the wind speed to be 3.8 m/s. The overall heat
loss

coefficient for the collector has been calculated. Also, the heat
re-
moval factor, the useful energy, the absorber plate temperature
have been calculated.
For the present case study, the total amount of fuel consump-
tion in winter season for both space heating and domestic hot
water (300 L/day) when the conventional boiler system is used,
is 4.815 m3/season. The amount of fuel consumed in summer
sea-
son for the domestic hot water when the boiler alone has been
used is 0.3867 m3/season. However, the total amount of the fuel
consumption all around the year for domestic hot water is about
0.6766 m3/year if the boiler alone is used. The current price of
the fuel cost in Jordan is 0.33 JD for 1 L of diesel. The total
cost of
fuel in 1 year using boiler only is 314.5 JD/year. With respect
to
the heating space, the total amount of the fuel consumed all
around the year for space heating for the case study is about
1.817 m3/year if the boiler alone is used. This quantity of fuel
costs
844.5 JD/year. The energy cost of domestic hot water and space
heating at different months for boiler system only is shown in
Fig. 7.
Fig. 8 presents the fuel cost required for space heating and
domestic hot water for the same case study, but in the case of
using
the integrated boiler–solar energy saving system. In the case of
the
integrated boiler–solar energy saving system, the total amount
of
0
5

10
15
20
25
30
35
40
0 2 4 6 8 10 12
Month
Te
m
pe
ra
tu
re
C
Tmin °C
Tmax °C
Fig. 6. The temperature distributions for the minimum and
maximum values of
ambient temperature at different months for Marka city.

the fuel consumed for domestic hot water is reduced to zero in
summer and to 0.2214 m3 in all around the year. Thus, the total
cost of fuel for domestic hot water in 1 year using the integrated
energy system is 106.4 JD/year.
The saving in energy with respect to the heating space is clearly
shown in Fig. 8. The total amount of the fuel consumed all
around
the year for space heating is about 1.28 m3/year and this
quantity
of fuel costs 597.1 JD/year. The total cost of fuel consumed for
the
domestic hot water in our case study if the conventional boiler
sys-
tem is used is 314.5 JD/year. This quantity is reduced to 106.4
JD/
year in the case of using an integrated energy saving system. A
comparison for the energy cost of domestic hot water between
the combined integrated energy boiler–solar system and the con-
ventional boiler system is shown in Fig. 9.
Fig. 10 presents similar results as shown in Fig. 11, but the
com-
parison between the combined integrated system and the
conven-
tional system is based on the energy requirement for space
heating. The total cost of fuel needed for space heating is
reduced
from 844.5 JD/year in the case of using the conventional boiler
sys-
tem to 597.1 JD/year in the case of using an integrated energy
sav-
ing system.
The amount of fuel consumed during a whole year if the con-
ventional boiler system is used for the present case study is

2.49 m3/season. The most quantity of fuel consumption is
needed
in winter season for space heating. About 89% from the fuel
energy
requirement is used in winter season which is about 2.20
m3/sea-
0
50
100
150
200
250
Fu
el
C
os
t (
$
U
S
)
Space Heating (Boiler only)

Space Heating (Integrated Boiler-Solar)
Ja
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ar
y
Fe
br
ua
ry
M
ar
ch
A
pr
il
M
ay
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ne
Ju
ly
A
ug

us
t
Se
pt
em
be
r
O
ct
ob
er
N
ov
em
be
r
D
ec
em
be
r
Month
Fig. 10. A comparison between the energy needed for space

heating in the case of
the conventional boiler system and the integrated combined
system.
0
50
100
150
200
250
300
Fu
el
C
os
t (
$
U
S
)
Total Fuel Cost (Boiler only)
Total Fuel Cost (Integrated System)

Se
pt
em
be
r
O
ct
ob
er
N
ov
em
be
r
D
ec
em
be
r
Month
Fig. 11. A comparison between the total energy requirement for
domestic hot
water and space heating for the conventional boiler system and
the integrated

system at different months.
0%
20%
40%
60%
80%
100%
120%
Ja
nu
ar
y
Fe
br
ua
ry
M
ar
ch
A
pr
il

M
ay
Ju
ne
Ju
ly
A
ug
us
t
Se
pt
em
be
r
O
ct
ob
er
N
ov
em
be

r
D
ec
em
be
r
Month
%
o
f E
ne
rg
y
S
av
in
g
Perecentage of Energy Saving
Fig. 12. Percentage of energy saving as a function of the time
around the year in the
case of using the combined integrated boiler–solar energy
instead of boiler only.
0

5
10
15
20
25
30
35
Fu
el
C
os
t (
$
U
S
)
Domestic Hot Water (Boiler only)
Domestic Hot Water (Integrated System)
Ja
nu
ar
y

Fe
br
ua
ry
M
ar
ch
A
pr
il
M
ay
Ju
ne
Ju
ly
A
ug
us
t
Se
pt
em
be

r
O
ct
ob
er
N
ov
em
be
r
D
ec
em
be
r
Month
Fig. 9. A comparison between the energy demand for domestic
hot water in the
case of the conventional boiler system and the integrated
combined system at
different months.
(2010) 1621–1628 1627
son. The amount of fuel consumed in summer season for both

space heating and domestic hot water in the case of the conven-
tional boiler system is about 0.29 m3/season which is less than
11% from the total energy requirement.
Furthermore, the amount of fuel consumed for both space heat-
ing and domestic hot water in the case of the combined
integrated
system is 1.5 m3/year which is 1 m3 less than the energy needed
in
case of the conventional energy system. The amount of fuel
needed
in winter season for both space heating and domestic hot water
in
the case of the combined integrated system is about 99% from
the
total required energy in the whole year. Fig. 11 shows a
compari-
son between the total energy cost for both space heating and
domestic hot water of the two energy systems.
The percentage of energy saving system ranges from 27% at
winter season to 100% at summer season as shown in Fig. 12.
Of
course, reducing 40% of the annual domestic hot water and
space
heating saves 330 JD each year of the fuel cost which is typical
for families of 2–4. Larger families and larger space building
save
even more.
6. Conclusions
The aim of the present study was to develop and demonstrate
both the technical and economical viability of a combined solar
boiler integrated system that can run alternately, or simulta-
neously to reduce the yearly energy bill which was increased 3
times in the last 2 years in Jordan. The feasibility of the

combined
solar boiler integrated system concept has been demonstrated.
The economical study about the integration system of boiler and
solar energy shows that using solar water heaters to heat space
and
for domestic water is cost-effective. Payback can be as low as 3
years,
and utility bills are much lower than they would be using a
conven-
tional heating system. The payback period can be slightly
changed
depending on the fluctuation fuel price in the world market.
With space and water heating by using a flat-plate solar collec-
tor, about 39% of home energy use can be reduced. Therefore,
the
solar energy is an attractive method of reducing a home’s fossil
fuel
consumption. The under-floor heating system has a high
efficiency
and can be installed mainly in new buildings. However, for the
existing buildings, fan coil units might be more suitable. Evacu-
ated-tube is more efficient and commercial than the flat-plate
solar
collectors.
References
[1] Hrayshat ES, Al-Soud MS. Solar energy in Jordan: current
state and prospects.
Renew Sustain Energy Rev 2004;8:193–200.
[2] Al-Salaymeh A. Modelling of global daily solar radiation on
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[3] Blumenberg I, Bentenrieder M, Kerschensteiner H, AlTaher
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[4] Mohsen M, Akash B. Evaluation of domestic solar water
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York: John Wiley and Sons; 1991.
[16] Audi M, Alsaad M. Simple hourly global solar radiation
prediction models.
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Jordan. Solar Wind

Technol 1990;7(3):473–7.
[18] Audi M, Alsaad M. A general model for the prediction of
hourly diffuse solar
radiation. Sol Energy 1991;10(1):39–45.
[19] Alsaad M, Hammad M. Heating and air conditioning, 4th
ed. Local publisher,
National Library Department Cataloging-in-Publication Data;
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[20] Royal Scientific Society. The potential of solar energy
application in Jordan.
General background: energy situation in Jordan, vol. 1. Amman:
Jordan; 1983.
[21] The Royal Scientific Society. Manual of solar house.
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[22] Al-Salaymeh A, Al-Salaymeh M, Rabah M, Abdelkader M.
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In: Proceedings of the 2nd international conference on thermal
engineering
theory and applications. January 3–6, Al Ain, UAE; 2006.
Economical investigation of an integrated boiler–solar energy
saving system in JordanIntroductionAim of the workTheoretical
backgroundCollector thermal performanceDesign of energy
saving systemResults and discussionsConclusionsReferences
Sheet1Enjoy Shopping for
clothingMaleFemaletotalYes136224360No10436140total240260
5001. What is the probability a shopper likes to shop for
clothing? 0.722. Given a shopper is male, what is the
probability the shopper likes to shop for clothes? 0.573. Given a

shopper is male, what is the probability the shopper does not
like to shop for clothing? 0.434. Given a shopper is female,
what is the probability a shopper does not like to shop? 0.14
Sheet2
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