applied
sciences
Article
Potential Study of Solar Thermal Cooling in
Sub-Mediterranean Climate
Mustafa Jaradat 1, Mohammad Al-Addous 1, Aiman Albatayneh 1, Zakariya Dalala 1and
Nesrine Barbana 2,*
1Department of Energy Engineering, German Jordanian University, Amman 11180, Jordan;
2Department of Environmental Technology, Technische Universität Berlin, 10623 Berlin, Germany
*Correspondence: [email protected]; Tel.: +49-030-314-28633
Received: 14 March 2020; Accepted: 30 March 2020; Published: 1 April 2020
Abstract:
Air conditioning is becoming increasingly important in the energy supply of buildings
worldwide. There has been a dramatic increase in energy requirements for cooling buildings in the
Middle East and North Africa (MENA) region. This is before taking the effects of climate change
into account, which will also entail a sharp increase in cooling requirements. This paper presents the
potential of using a solar thermal absorption cooling system in Sub-Mediterranean Climate. Four
sites in Jordan are now equipped with water-lithium bromide (H
2
O-LiBr) absorption chillers with
a total nominal capacity of 530 kW. The focus of the paper was on the pilot system at the German
Jordanian University (GJU) campus with a cooling capacity of 160 kW. The system was designed and
integrated in order to support two existing conventional compression chillers with a nominal cooling
capacity of 700 kW. The system was economically evaluated based on the observed cooling capacity
results with a Coefficient of Performance (COP) equals 0.32, and compared with the values observed
for a COP of 0.79 which is claimed by the manufacturer. Several techniques were implemented to
evaluate the overall economic viability in-depth such as present worth value, internal rate of return,
payback period, and levelized cost of electricity. The aforementioned economic studies showed that
the absorption cooling system is deemed not feasible for the observed COP of 0.32 over a lifespan
of 25 years. The net present value was equal to
−
137,684 JD and a payback period of 44 years
which exceeds the expected lifespan of the project. Even for an optimal operation of COP =0.79,
the discounted payback period was equal to 23 years and the Levelized Cost of Electricity (LCOE)
was equal to 0.65 JD/kWh. The survey shows that there are several weaknesses for applying solar
thermal cooling in developing countries such as the high cost of these systems and, more significantly,
the lack of experience for such systems.
Keywords:
thermally driven refrigeration; absorption chillers; solar collectors; solar air conditioning;
feasibility study; present worth value; payback period
1. Introduction
The increasing desire for air conditioning is mainly due to the demanding modern codes and
standards on ventilation and indoor air quality [
1
,
2
], according to modern glass buildings in hot dry
areas without considering of the climate and character of the country [3].
In countries with a generally high need for air conditioning, considerable load peaks (summer
peaks) occur in the public power grid, especially on hot summer days [
4
]. Complete blackouts in
network supply have already occurred [
4
]. The energy supply companies must respond to the growing
need for air conditioning and cooling by expanding investment-intensive peak load power plants.
Appl. Sci. 2020,10, 2418; doi:10.3390/app10072418 www.mdpi.com/journal/applsci
Appl. Sci. 2020,10, 2418 2 of 17
A relief strategy for the power grids is observed in the substitution of the conventional electrically
driven compression refrigeration system with thermally driven processes. In particular, the solar drive
heat is an attractive technology solution due to the coincidence between cooling requirements and
solar radiation. The extensive simultaneousness (seasonal and over the day) between solar supply and
occurring cooling load in buildings suggests the use of solar energy to provide the required drive heat.
The highest cooling loads occur at those hours when high radiation power is available (e.g., office
building), which could be attributed to either the user profile or the cooling loads which are strongly
linked to the radiation on the building envelope. [5,6].
The solar thermal air conditioning processes do not use environmentally harmful refrigerants [
7
].
Traditional refrigeration and air conditioning systems mainly use refrigerants that have a high potential
for global warming [
8
]. Developments in the direction of natural refrigerants (propane, CO
2
) offer
alternatives, but these are not yet very widespread in current refrigeration or air conditioning systems.
Therefore, by switching to thermal cooling processes, harmful substances are reduced.
The systems of »solar thermal cooling« primarily use solar energy as a thermal drive source for
cooling. In well-designed and working systems for solar thermal cooling, primary energy savings can
be achieved compared to conventional systems. This corresponds to a reduction in CO
2
emissions
in accordance with the annual Heating, Ventilation and Air Conditioning (HVAC) electricity energy
savings [
9
]. The use of electrical auxiliary energy is mainly consumed by driving pumps and fans of
the solar thermal cooling system.
There are a variety of ways to convert solar energy into useful cooling or conditioned air (cooling
and dehumidification). The combination of photovoltaics with compression cooling also offers these
advantages. If only looking at the cooling side, photovoltaics in combination with compression cooling
could be competitive in the future. However, the great ecological advantage of solar thermal cooling
systems does not lie in the cooling side, but in the multiple uses of the solar systems for water heating
and heating support, which could achieve the majority of the CO2savings [10].
Many studies have been accomplished related to thermal driven solar cooling and air conditioning.
Solar thermal cooling can be mainly classified as open and closed cycles. In open cycles, operated at
atmospheric pressure, the latent load (dehumidification) is handled using solid or liquid desiccants.
The water vapour in the air is considered as a sorbate while the solid or liquid desiccant is considered
as adsorbent or absorbent, respectively. Open processes consist of a combination of sorption
dehumidification and evaporative cooling, whereby a wide variety of interconnections are possible and
different sorbents are used. The most common method uses sorption rotors for dehumidification. Up to
now, the rotor materials used have only been either silica gel or lithium chloride, which is incorporated
into a cellulose matrix. Several studies were performed for desiccant evaporative cooling systems
(DEC) applying liquid desiccants such as [11,12] and applying desiccant wheels such as in [13,14].
Closed processes are represented by adsorption and absorption chillers. Adsorption refrigeration
systems use a solid to adsorb the refrigerant. Devices on the market use mainly silica gel as the
adsorbent and water as the refrigerant [
15
]. The COP values of the systems are in the range of
0.65 and heat from approximately 60
◦
C can be used to provide cooling at correspondingly low
re-cooling temperatures, [
16
]. The COP of adsorption chiller of 0.65 is obtainable only for high
desorption temperatures, high cooled water temperatures, and low cooling temperatures. For the
heating temperatures as low as 60
◦
C, it is drastically lower (down to 0.17–0.34) [
17
]. These systems
have some special features due to the periodic adsorption and desorption of the sorbents. As a rule,
two adsorbers are operated alternately, so that one adsorber is always available for the provision of
cold. This periodic operation leads to fluctuating temperatures at all temperature levels, a constraint
that must be taken into account when planning the system [18].
The main absorption chiller systems are the water-lithium bromide (H
2
O-LiBr) and the ammonia
water (NH
3
-H
2
O) systems. The H
2
O-LiBr systems are generally used for air conditioning in buildings.
The NH
3
-H
2
O systems are used for refrigeration applications with usable temperatures below the
freezing point of water. For H
2
O-LiBr, single-stage absorption chillers typically achieve a COP at
Appl. Sci. 2020,10, 2418 3 of 17
the nominal operating point of around 0.7–0.8 and require drive temperatures above 75
◦
C [
19
].
Double-stage absorption chillers have another generator–condenser pair to the components of a
single-stage absorption chiller, and a higher utilization of the heat supply can be achieved. Such
systems are mainly offered in the area of large cooling capacities and achieve COP values from 1.1 to
1.2. The drive temperatures required are typically above 140 ◦C [20].
The greatest market potential for solar thermal cooling lies in the international market, in countries
with a high solar radiation supply and therefore also a higher need for building and commercial
cooling. Large sales markets are located in China, the USA, Japan, and Southeast Asia [15].
Thermally operated chillers are currently available on the market for the output range from 5 kW
cooling to the megawatt range, as well as suppliers for DEC systems with an air volume flow of
4000 m
3
/h and above. However, only around 1350 solar cooling systems were installed worldwide
by the end of 2015 [
21
]. Figure 1shows the market development between 2004–2015 for small to
large-scale cooling and air conditioning systems [21].
Appl. Sci. 2020, 10, x FOR PEER REVIEW 3 of 17
nominal operating point of around 0.7–0.8 and require drive temperatures above 75 °C [19]. Double-
stage absorption chillers have another generator–condenser pair to the components of a single-stage
absorption chiller, and a higher utilization of the heat supply can be achieved. Such systems are
mainly offered in the area of large cooling capacities and achieve COP values from 1.1 to 1.2. The
drive temperatures required are typically above 140 °C [20].
The greatest market potential for solar thermal cooling lies in the international market, in
countries with a high solar radiation supply and therefore also a higher need for building and
commercial cooling. Large sales markets are located in China, the USA, Japan, and Southeast Asia
[15].
Thermally operated chillers are currently available on the market for the output range from 5
kW cooling to the megawatt range, as well as suppliers for DEC systems with an air volume flow of
4000 m³/h and above. However, only around 1350 solar cooling systems were installed worldwide by
the end of 2015 [21]. Figure 1 shows the market development between 2004–2015 for small to large-
scale cooling and air conditioning systems [21].
Figure 1. Number of solar cooling installations between 2004 and 2015. Reproduced with permission
from [21], Copyright AIP Publishing, 2016.
The aim of this paper is to investigate and assess four H₂O-LiBr absorption chiller pilot plants
located in different sites in Jordan. These pilot plants were funded by the German Corporation for
International Cooperation GmbH (GIZ) on behalf of Federal Ministry for the Environment, Nature
Conservation, Buildings and Nuclear safety of the Federal Republic of Germany. The current status
of the installed systems is to be discussed. The absorption chillers have a total nominal cooling
capacity of 530 kW (150 RT). The focus of the research was on the pilot system at the German
Jordanian University campus. The system has a capacity of 160 kW for cooling and a 50 kW for
heating. The system was designed and integrated in order to support the existing conventional
compression system with a cooling capacity of 700 kW. Furthermore, an economic study was also
carried out for the absorption system taking the environment effect of the reduction of CO₂ emissions
into account.
2. Sites Description
Four absorption chillers were installed in four sites in Jordan. The sites represent different
climate conditions that varied from a Mediterranean climate in Irbid (North-West) to a continental
Figure 1.
Number of solar cooling installations between 2004 and 2015. Reproduced with permission
from [21], Copyright AIP Publishing, 2016.
The aim of this paper is to investigate and assess four H
2
O-LiBr absorption chiller pilot plants
located in different sites in Jordan. These pilot plants were funded by the German Corporation for
International Cooperation GmbH (GIZ) on behalf of Federal Ministry for the Environment, Nature
Conservation, Buildings and Nuclear safety of the Federal Republic of Germany. The current status of
the installed systems is to be discussed. The absorption chillers have a total nominal cooling capacity of
530 kW (150 RT). The focus of the research was on the pilot system at the German Jordanian University
campus. The system has a capacity of 160 kW for cooling and a 50 kW for heating. The system was
designed and integrated in order to support the existing conventional compression system with a
cooling capacity of 700 kW. Furthermore, an economic study was also carried out for the absorption
system taking the environment effect of the reduction of CO2emissions into account.
2. Sites Description
Four absorption chillers were installed in four sites in Jordan. The sites represent different climate
conditions that varied from a Mediterranean climate in Irbid (North-West) to a continental climate in
Madaba (inner regions), to an arid climate in Petra (south). Figure 2shows the four sites on a map of
Jordan together with the annual radiation on horizontal surfaces [22].
Appl. Sci. 2020,10, 2418 4 of 17
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climate in Madaba (inner regions), to an arid climate in Petra (south). Figure 2 shows the four sites
on a map of Jordan together with the annual radiation on horizontal surfaces [22].
Figure 2. Map of Jordan with the four installed absorption chillers, encircled by red circles,
accompanied with the annual radiation on horizontal surfaces. Reproduced with permission from
[22], Copyright AIP Publishing, 2016.
2.1. Climate Conditions in Jordan
Jordan is located 80 km to the east of the Mediterranean Sea between latitudes 29°11′–32°42′ N
and longitudes 34°54′–38°15′ E, with an area of 89,329 km2 [23]. The climate of Jordan is
predominantly of the Mediterranean type. It is marked by sharp seasonal variations in both
temperature and precipitation. Summers are hot and dry while winters are cool and wet. Summer
starts around the middle of May and winter starts around the middle of November, with two short
transitional periods in between.
The temperature in Jordan varies by location and seasons. The temperature in the hilly regions
experience cold weather with temperatures below 0 °C. The summer temperature can reach
temperatures above 30 °C (as monthly average temperatures).
2.2. Climate Conditions of the Selected Sites
2.2.1. Irbid: Irbid Chamber of Commerce
The solar cooling unit has been installed at Irbid Chamber of Commerce since 2016. Irbid is
located in the North of Jordan. Irbid is characterized by a semi-arid climate with high annual solar
irradiation above 2000 kW/h, as shown in Figure 2. Heating is required during winter months in
which the ambient temperatures drop significantly.
2.2.2. Amman: Royal Culture Centre
Figure 2.
Map of Jordan with the four installed absorption chillers, encircled by red circles, accompanied
with the annual radiation on horizontal surfaces. Reproduced with permission from [
22
], Copyright
AIP Publishing, 2016.
2.1. Climate Conditions in Jordan
Jordan is located 80 km to the east of the Mediterranean Sea between latitudes 29
◦
11
0
–32
◦
42
0
N and
longitudes 34
◦
54
0
–38
◦
15
0
E, with an area of 89,329 km
2
[
23
]. The climate of Jordan is predominantly of
the Mediterranean type. It is marked by sharp seasonal variations in both temperature and precipitation.
Summers are hot and dry while winters are cool and wet. Summer starts around the middle of May
and winter starts around the middle of November, with two short transitional periods in between.
The temperature in Jordan varies by location and seasons. The temperature in the hilly
regions experience cold weather with temperatures below 0
◦
C. The summer temperature can
reach temperatures above 30 ◦C (as monthly average temperatures).
2.2. Climate Conditions of the Selected Sites
2.2.1. Irbid: Irbid Chamber of Commerce
The solar cooling unit has been installed at Irbid Chamber of Commerce since 2016. Irbid is
located in the North of Jordan. Irbid is characterized by a semi-arid climate with high annual solar
irradiation above 2000 kW/h, as shown in Figure 2. Heating is required during winter months in which
the ambient temperatures drop significantly.
2.2.2. Amman: Royal Culture Centre
Located at Jordan’s capital, Amman, which has an annual solar irradiation of above 2100 kW/h,
the absorption system has been in operation since 2016 and it has 8 to 16 operating hours a day,
the cooling demands are highest in the evening hours where most events take place. Thus, the system
is equipped with hot water storage to allow cooling and heating of non-solar hours.
Appl. Sci. 2020,10, 2418 5 of 17
2.2.3. Madaba: German Jordanian University
This absorption chiller has been in operation since 2015 and is located at the German Jordanian
University close to the ancient city of Madaba. Madaba has hot and dry summers with abundant
sunshine, more than 300 days per year. The cooling demand is for 6 to 10 h per day and is highest at
noon time with ambient temperatures that can reach 40 ◦C. This system is the focus of this study.
2.2.4. Petra: Petra Guest House
The absorption chiller is located at the gates of the UNESCO world heritage site of Petra and it
has been in operation since February 2015 at the Petra Guest House. Petra has a hot and dry climate
with an annual solar radiation above 2300 kW/h with ambient temperature up to 45
◦
C. the system
operates daily for 24 h (24/7). The system is equipped with a thermal energy storage of 12 m
3
as driving
heat after sunset is connected with a stand-by conventional compression for hours with peak load.
An overview of the installed absorption chillers is listed in Table 1[24].
Table 1. An overview of the installed absorption chillers.
Irbid Chamber
of Commerce
Royal Culture
Centre
German Jordanian
University
Petra Guest
House
Location Irbid Amman Madaba Petra
Nominal cooling capacity, kW 50 160 160 160
Gross solar collector area, m2140 449 480 388
Operating hours per day 6–12 8–16 6–10 24
Chilled water supply temperature, ◦C 8–10 8–10 6–8 9–11
3. GJU System Description
3.1. Description of the Installation Site
The existing solar heating and cooling system was installed on the rooftop of building C in the
campus of the German Jordanian University (GJU) in Jordan. GJU is a public university with around
5000 students, located near Madaba, Jordan. The absorption system under consideration is used to
support the already-existing conventional compression system for Building C. The cooling capacity of
Building C is equal to 700 kW and the share of H
2
O-LiBr was planned to be around 11% of the total
cooling capacity, i.e., 160 kW. Building C consists of four levels and a basement with a total floor area
of about 7500 m
2
. The ground and the third floors consist mainly of laboratories and offices. The first
and the second floors consist mainly of education rooms in addition to the academic staffoffices.
3.2. Meteorological Data
The Photovoltaic Geographical Information System (PVGIS) tool was used to generate Typical
Meteorological Year (TMY) data of solar radiation, temperature, and other meteorological data [
25
].
The data was provided by the typical meteorological year (TMY2) format containing hourly global and
beam radiation data in addition to ambient temperature and sunshine duration values. The considered
period for the data that was exported was from 1991–2010. Figures 3and 4show the metrological data
(daily ambient temperature and daily average global and diffuse radiation in June 2015) in the site over
a period of a year.
The air temperature data for year 2015 in Madaba is presented in Figure 3. Madaba has an
inland climate with large air temperature fluctuations across the seasons. In typical summer months
(May–September), the highest air temperature normally occurs in June and between 12:00 and 14:00
where the air dry bulb temperature could reach 40
◦
C. The solar radiation normally reaches its peak
value of around 1030 W/m2between 9:00 and 15:00, as shown in Figure 4.
Appl. Sci. 2020,10, 2418 6 of 17
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the air dry bulb temperature could reach 40 °C. The solar radiation normally reaches its peak value
of around 1030 W/m2 between 9:00 and 15:00, as shown in Figure 4.
Figure 3. Daily ambient temperature at German Jordanian University (GJU) campus.
Figure 4. Daily average irradiance for June 2015 in the installation site at the GJU campus.
3.3. System Description
The solar heating and cooling system was installed on the rooftop of building C at the GJU
campus. The solar heating system consists of 30 solar collector arrays each with five modules
connected in series. Each module (model CPC1518) has 18 evacuated tube collectors with compound
parabolic collector (CPC) geometry. The aperture total surface area of the solar field was 450 m2 and
the collectors were oriented to face the south with a tilt angle of 45°. Figure 5 shows the solar collector
field installed on the rooftop of Building C at the GJU campus.
Figure 3. Daily ambient temperature at German Jordanian University (GJU) campus.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 6 of 17
the air dry bulb temperature could reach 40 °C. The solar radiation normally reaches its peak value
of around 1030 W/m2 between 9:00 and 15:00, as shown in Figure 4.
Figure 3. Daily ambient temperature at German Jordanian University (GJU) campus.
Figure 4. Daily average irradiance for June 2015 in the installation site at the GJU campus.
3.3. System Description
The solar heating and cooling system was installed on the rooftop of building C at the GJU
campus. The solar heating system consists of 30 solar collector arrays each with five modules
connected in series. Each module (model CPC1518) has 18 evacuated tube collectors with compound
parabolic collector (CPC) geometry. The aperture total surface area of the solar field was 450 m2 and
the collectors were oriented to face the south with a tilt angle of 45°. Figure 5 shows the solar collector
field installed on the rooftop of Building C at the GJU campus.
Figure 4. Daily average irradiance for June 2015 in the installation site at the GJU campus.
3.3. System Description
The solar heating and cooling system was installed on the rooftop of building C at the GJU campus.
The solar heating system consists of 30 solar collector arrays each with five modules connected in series.
Each module (model CPC1518) has 18 evacuated tube collectors with compound parabolic collector
(CPC) geometry. The aperture total surface area of the solar field was 450 m
2
and the collectors were
oriented to face the south with a tilt angle of 45
◦
. Figure 5shows the solar collector field installed on
the rooftop of Building C at the GJU campus.
The solar field is supplying the absorption chiller with water at 85
◦
C, this amounts to 44 MWh
seasonal thermal energy for the absorption chiller of 250 MWh produced by the collectors. Four heat
storage tanks each with a volume of 3.5 m
3
were integrated to the solar heating system. One of the
storage tanks is used for domestic hot water in building C and the other three hot water storage tanks
were connected to the absorption chiller’s generator. The solar hydraulic system is equipped with hot
water pumps for each storage tank, two gas boilers (380 kW total capacity), and a dry cooler to remove
excess heat.
The conventional cooling system consists of two air cooled multistage compression chillers,
700 kW each (one duty/one stand-by), and one of them can also work as a heat pump which operates
only if the heating load reaches beyond the capacity of the solar field and the two boilers in cold winter
days when there is no or minimum solar energy gain. The evaporator of the air-cooled multistage
compression chillers provides chilled water in summer at a given set value for the chilled water outlet
Appl. Sci. 2020,10, 2418 7 of 17
temperature, this temperature is set at 9
◦
C. The used refrigerant is R134a and is cooled down in an
air-cooled condenser.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 7 of 17
Figure 5. Solar collector field installed on the rooftop of Building C at GJU.
The solar field is supplying the absorption chiller with water at 85 °C, this amounts to 44 MWh
seasonal thermal energy for the absorption chiller of 250 MWh produced by the collectors. Four heat
storage tanks each with a volume of 3.5 m3 were integrated to the solar heating system. One of the
storage tanks is used for domestic hot water in building C and the other three hot water storage tanks
were connected to the absorption chiller’s generator. The solar hydraulic system is equipped with hot
water pumps for each storage tank, two gas boilers (380 kW total capacity), and a dry cooler to remove
excess heat.
The conventional cooling system consists of two air cooled multistage compression chillers, 700
kW each (one duty/one stand-by), and one of them can also work as a heat pump which operates
only if the heating load reaches beyond the capacity of the solar field and the two boilers in cold
winter days when there is no or minimum solar energy gain. The evaporator of the air-cooled
multistage compression chillers provides chilled water in summer at a given set value for the chilled
water outlet temperature, this temperature is set at 9 °C. The used refrigerant is R134a and is cooled
down in an air-cooled condenser.
A 160 kW single-stage H2O-LiBr absorption chiller developed by the Technical University of
Berlin was used to assist the conventional cooling system. The system was designed in a way that it
does not interfere negatively with the existing compression system and operates in a way that it can
be started and stopped independently from the old system. It was designed to cool a part of the
airstream exiting the building down to 16 °C contingent on the solar energy gain. Hot water from the
solar field enters the generator with a volume flow rate of 3.3 L/s. The heat sink for the condenser and
the absorber is cooled with a water-stream leaving a 300-kW dry cooler with a volume flow rate of
12 L/s and temperature range between 30 to 40 °C. The evaporator provides chilled water with a
volume flow rate varies between 3.5 to 8 L/s and temperature between 8 and 10 °C, depending on the
generation water temperature. The major components of the absorption refrigeration system are two
large containers, the low-pressure tank, and the high-pressure tank. The unit contains the four copper
tube heat exchangers: evaporator, absorber, generator, and condenser. The external circuits for the
chilled, cooling, and heating water were connected to the four copper tube heat exchangers.
The internal sensors of the system consist of temperature and pressure sensors. The pressure in
the vapor space of the three containers and the pressure in the absorber and the evaporator bottoms
are measured. The temperature is measured at nine positions; this includes the reservoirs for the
desorber, absorber, and evaporator, the condenser refrigerant sump of the evaporator circuit as well
as all the inlets and outlets of the solution heat exchanger. The flow rate for the different circuits: solar
collector field, generator, condenser, evaporator, and the compression chillers were measured via five
ultrasonic flow meters. The ultrasonic heat flow meter (Ultraflow 54 DN 150–250) for the installation
into the main chilled-water network and for the remaining circuits the ultrasonic heat flow meter
devices T550 ULTRACOLD (UH50) and T550 ULTRAHEAT (UH50) were used.
The measurement of the global solar irradiance on a horizontal surface is carried out by means
of a pyranometer. The measurement of the ambient air is carried out by means of the sensor unit type
Figure 5. Solar collector field installed on the rooftop of Building C at GJU.
A 160 kW single-stage H
2
O-LiBr absorption chiller developed by the Technical University of
Berlin was used to assist the conventional cooling system. The system was designed in a way that
it does not interfere negatively with the existing compression system and operates in a way that it
can be started and stopped independently from the old system. It was designed to cool a part of the
airstream exiting the building down to 16
◦
C contingent on the solar energy gain. Hot water from the
solar field enters the generator with a volume flow rate of 3.3 L/s. The heat sink for the condenser
and the absorber is cooled with a water-stream leaving a 300-kW dry cooler with a volume flow rate
of 12 L/s and temperature range between 30 to 40
◦
C. The evaporator provides chilled water with a
volume flow rate varies between 3.5 to 8 L/s and temperature between 8 and 10
◦
C, depending on the
generation water temperature. The major components of the absorption refrigeration system are two
large containers, the low-pressure tank, and the high-pressure tank. The unit contains the four copper
tube heat exchangers: evaporator, absorber, generator, and condenser. The external circuits for the
chilled, cooling, and heating water were connected to the four copper tube heat exchangers.
The internal sensors of the system consist of temperature and pressure sensors. The pressure in
the vapor space of the three containers and the pressure in the absorber and the evaporator bottoms are
measured. The temperature is measured at nine positions; this includes the reservoirs for the desorber,
absorber, and evaporator, the condenser refrigerant sump of the evaporator circuit as well as all the
inlets and outlets of the solution heat exchanger. The flow rate for the different circuits: solar collector
field, generator, condenser, evaporator, and the compression chillers were measured via five ultrasonic
flow meters. The ultrasonic heat flow meter (Ultraflow 54 DN 150–250) for the installation into the
main chilled-water network and for the remaining circuits the ultrasonic heat flow meter devices T550
ULTRACOLD (UH50) and T550 ULTRAHEAT (UH50) were used.
The measurement of the global solar irradiance on a horizontal surface is carried out by means
of a pyranometer. The measurement of the ambient air is carried out by means of the sensor unit
type ARFT/A-I/S. In addition, the measurement of the electrical energy consumption (in kWh) of the
components necessary for the solar cooling application was taken. The measurement of the electrical
energy of components is completed by means of the watt-hour meter type iEM3150. Figure 6shows
the 160 kW H2O-LiBr absorption chiller at GJU Building’s C roof.
Appl. Sci. 2020,10, 2418 8 of 17
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ARFT/A-I/S. In addition, the measurement of the electrical energy consumption (in kWh) of the
components necessary for the solar cooling application was taken. The measurement of the electrical
energy of components is completed by means of the watt-hour meter type iEM3150. Figure 6 shows
the 160 kW H₂O-LiBr absorption chiller at GJU Building’s C roof.
Figure 6. Water-lithium bromide (H₂O-LiBr) 160 kW absorption chiller on GJU rooftop.
4. Economic Feasibility
This economic study is intended to evaluate the overall economic viability in-depth. The key
financial indicators used for the evaluation include Present Worth (PW), Payback Period, and Internal
Rate of Return (IRR).
The method is the equivalent worth of all cash flows relative to some base or beginning
point in time dubbed the present. That is, all cash revenues (incomes, saved energy, reduced CO₂
emissions) and expenses (auxiliary power consumption, maintenance) are discounted to the present
point in time at an interest rate [26]. A positive PW for the absorption cooling system will mean that
the project is feasible and a profit over the minimum amount required will be achieved. To find the
as a function of interest rate (%) of the cash inflows and outflows, the future amounts need to
be discounted to the present by applying Equation (1) [27]. To discount future amounts to the present
by using the interest rate over the appropriate study period, we used the following:
(
%
)
=
(
1
+
)
+
(
1
+
)
−
1
(
1
+
)
(1)
where (%) is the effective interest rate; () is the index for each compounding period (0≤≤);
() is future cash flow at the end of period (); () is the end-of-period cash flows in a uniform
series continuing for a specified number of periods, starting at the end of the first period and
continuing through the last period; and () is the number of compounding periods in the study
period. In this study, was set to 25 years which represents the life expectancy of the system and
the interest rate which was set to =6%.
Annual expenses include the maintenance costs and the operating energy and water costs. For
maintenance costs, standards like the Association of German Engineers (VDI) 2067 use 2% of the
investment costs. Chiller manufacturers calculate maintenance costs by 1% of the investment costs.
For large thermal chillers, companies offer constant cost maintenance: the costs vary between 0.5%
for large machines (up to 700 kW) up to 3% for lower-power machines [28].
The payback period is the time required to recover the total investments by profit gaining. The
payback period can be calculated by setting PW to 0. The simple payback period, θ, ignores the time
Figure 6. Water-lithium bromide (H2O-LiBr) 160 kW absorption chiller on GJU rooftop.
4. Economic Feasibility
This economic study is intended to evaluate the overall economic viability in-depth. The key
financial indicators used for the evaluation include Present Worth (PW), Payback Period, and Internal
Rate of Return (IRR).
The PW method is the equivalent worth of all cash flows relative to some base or beginning point
in time dubbed the present. That is, all cash revenues (incomes, saved energy, reduced CO
2
emissions)
and expenses (auxiliary power consumption, maintenance) are discounted to the present point in time
at an interest rate [
26
]. A positive PW for the absorption cooling system will mean that the project is
feasible and a profit over the minimum amount required will be achieved. To find the PW as a function
of interest rate (i%) of the cash inflows and outflows, the future amounts need to be discounted to the
present by applying Equation (1) [
27
]. To discount future amounts to the present by using the interest
rate over the appropriate study period, we used the following:
PW(i%)=
N
X
k=0
Fk(1+i)−k
+
A
(1+i)k−1
i(1+i)k
(1)
where (i%) is the effective interest rate; (k) is the index for each compounding period 0
≤
k
≤
N; (F
k
)
is future cash flow at the end of period (k); (A) is the end-of-period cash flows in a uniform series
continuing for a specified number of periods, starting at the end of the first period and continuing
through the last period; and (N) is the number of compounding periods in the study period. In this
study, Nwas set to 25 years which represents the life expectancy of the system and the interest rate
which was set to i=6%.
Annual expenses include the maintenance costs and the operating energy and water costs.
For maintenance costs, standards like the Association of German Engineers (VDI) 2067 use 2% of the
investment costs. Chiller manufacturers calculate maintenance costs by 1% of the investment costs.
For large thermal chillers, companies offer constant cost maintenance: the costs vary between 0.5% for
large machines (up to 700 kW) up to 3% for lower-power machines [28].
The payback period is the time required to recover the total investments by profit gaining.
The payback period can be calculated by setting PW to 0. The simple payback period,
θ
, ignores the
time value of money and all cash flows that occur after
θ
(
θ≤
N) and calculates the number of years
Appl. Sci. 2020,10, 2418 9 of 17
required for cash inflows (Revenues R) to just equal cash outflows (Expenses, E). For this study, where
initial investment occurs at time 0, the simple payback period is given in Equation (2) [27]:
θ
X
k=1
(Rk−Ek)−I≥0 (2)
In addition, the discounted payback period,
θ0
(
θ0≤
N), is calculated so that the time value of
money is considered, as given in Equation (3) [27]:
θ0
X
k=1
(Rk−Ek)(P/F,i%, k)−I≥0 (3)
4.1. Absorption Chiller Monitoring Results
The absorption chiller was monitored on several sunny summer days between May and July 2015.
The cooling capacity and the thermal COP as a function of generation temperature (T
g
) are shown in
Figure 7[
29
]. As shown in Figure 7, the cooling capacity varies and the maximum value reached about
30 kW with a mean daily generator temperature reaching values not higher than 80
◦
C. The thermal
coefficient of performance is defined as the ratio of the cooling achieved in the evaporator of the
absorption chiller to the driving heat applied to the generator. The COP of the absorption chiller varied
significantly depending on the operating conditions. Low COP values were observed, varying between
0.09 to 0.54 compared to 0.79 as claimed by the manufacturer regarding of the operating conditions.
The absorber and condenser mean daily temperature is between 24
◦
C and 38
◦
C with maximum
ambient air temperatures reaching 41
◦
C. The mean daily evaporator temperature is between 8
◦
C and
15 ◦C.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 9 of 17
value of money and all cash flows that occur after (≤) and calculates the number of years
required for cash inflows (Revenues R) to just equal cash outflows (Expenses, E). For this study,
where initial investment occurs at time 0, the simple payback period is given in Equation (2) [27]:
(
−
)
−
≥
0
(2)
In addition, the discounted payback period, (≤), is calculated so that the time value of
money is considered, as given in Equation (3) [27]:
(
−
)
(
/
,
%
,
)
−
≥
0
(3)
4.1. Absorption Chiller Monitoring Results
The absorption chiller was monitored on several sunny summer days between May and July
2015. The cooling capacity and the thermal COP as a function of generation temperature () are
shown in Figure 7 [29]. As shown in Figure 7, the cooling capacity varies and the maximum value
reached about 30 kW with a mean daily generator temperature reaching values not higher than 80
°C. The thermal coefficient of performance is defined as the ratio of the cooling achieved in the
evaporator of the absorption chiller to the driving heat applied to the generator. The COP of the
absorption chiller varied significantly depending on the operating conditions. Low COP values were
observed, varying between 0.09 to 0.54 compared to 0.79 as claimed by the manufacturer regarding
of the operating conditions. The absorber and condenser mean daily temperature is between 24 °C
and 38 °C with maximum ambient air temperatures reaching 41 °C. The mean daily evaporator
temperature is between 8 °C and 15 °C.
Figure 7. Cooling capacity and thermal Coefficient of Performance (COP) of the absorption chiller in
GJU as a function of driving temperature, modified from [29].
The main result to investigate is the observed cooling capacity of just 18.7%, at maximum of the
nominal cooling capacity value (160 kW). in addition, an average thermal COP of less than 0.3 can be
observed. An explanation was listed by [29], who attributed this to the operation of the absorption
chiller on non-demanding days (the University is closed on Fridays), the frequent operation of the
solar dry cooler, and some control and instrument issues.
Figure 7.
Cooling capacity and thermal Coefficient of Performance (COP) of the absorption chiller in
GJU as a function of driving temperature, modified from [29].
The main result to investigate is the observed cooling capacity of just 18.7%, at maximum of the
nominal cooling capacity value (160 kW). in addition, an average thermal COP of less than 0.3 can be
observed. An explanation was listed by [
29
], who attributed this to the operation of the absorption
chiller on non-demanding days (the University is closed on Fridays), the frequent operation of the
solar dry cooler, and some control and instrument issues.
Appl. Sci. 2020,10, 2418 10 of 17
4.2. Cost and Tariffs
In order to determine the economic feasibility of the absorption chiller system, an estimation
of the various components of the system was performed. A spreadsheet was tailored specifically to
the absorption chiller system to perform the economic mathematical analysis. Various parameters
were taken into account through the economic calculations. The system cost is defined through the
cost of the absorption chiller according to the cooling capacity per watt, and the cost of the auxiliary
component in the local market. Figure 8shows the component share of the total cost.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 10 of 17
4.2. Cost and Tariffs
In order to determine the economic feasibility of the absorption chiller system, an estimation of
the various components of the system was performed. A spreadsheet was tailored specifically to the
absorption chiller system to perform the economic mathematical analysis. Various parameters were
taken into account through the economic calculations. The system cost is defined through the cost of
the absorption chiller according to the cooling capacity per watt, and the cost of the auxiliary
component in the local market. Figure 8 shows the component share of the total cost.
Figure 8. Share of absorption system components in the total cost.
As shown, the solar field has the highest cost of the solar cooling system with a share of 42%.
The solar field at GJU was overdesigned regarding the supply of hot water to the generation of the
weak H₂O-LiBr solution, since the solar collector is also used for heating domestic hot water for
Building C. In addition, the solar field was overdesigned to ensure that the chiller was working with
a COP of 0.79 regardless of the outlet conditions. The installation and the operational cost are
considerably lower as a result of low local wages in Jordan compared to developing countries.
Table 2 shows the cost of the system components. The total cost of the system was 243,000 JD
(Jordanian Dinar). The absorption chiller has a cost of 546.8 JD/kW and a total of 87,480 JD. The solar
field total cost was equal to 102,060 with the highest cost share of the system. The heat rejection in the
condenser and the absorber has a cost share of 19,440 JD and the auxiliaries have a cost of 34,020 JD.
Table 2. Total cost and cost of each of the individual components for the absorption cooling system.
Component Cost in JD
Absorption chiller 87,480
Solar field 102,060
Heat rejection 19,440
Auxiliaries 34,020
Total 243,000
4.3. Economic Feasibility
The economic feasibility analysis of solar thermal cooling systems, which require high initial
investments, plays a very important role in the assessment of the viability of the project.
Figure 8. Share of absorption system components in the total cost.
As shown, the solar field has the highest cost of the solar cooling system with a share of 42%.
The solar field at GJU was overdesigned regarding the supply of hot water to the generation of the weak
H
2
O-LiBr solution, since the solar collector is also used for heating domestic hot water for Building C.
In addition, the solar field was overdesigned to ensure that the chiller was working with a COP of 0.79
regardless of the outlet conditions. The installation and the operational cost are considerably lower as
a result of low local wages in Jordan compared to developing countries.
Table 2shows the cost of the system components. The total cost of the system was 243,000 JD
(Jordanian Dinar). The absorption chiller has a cost of 546.8 JD/kW and a total of 87,480 JD. The solar
field total cost was equal to 102,060 with the highest cost share of the system. The heat rejection in the
condenser and the absorber has a cost share of 19,440 JD and the auxiliaries have a cost of 34,020 JD.
Table 2. Total cost and cost of each of the individual components for the absorption cooling system.
Component Cost in JD
Absorption chiller 87,480
Solar field 102,060
Heat rejection 19,440
Auxiliaries 34,020
Total 243,000
4.3. Economic Feasibility
The economic feasibility analysis of solar thermal cooling systems, which require high initial
investments, plays a very important role in the assessment of the viability of the project.
Appl. Sci. 2020,10, 2418 11 of 17
For assessing the financial feasibility of the system some financial metrics were used in this study;
namely the Net Present Value (NPV) and payback period. Net Present Value (NPV) is defined as the
difference between the present value of cash inflows and the present value of cash outflows. NPV is
used to analyse the profitability of a projected investment. The acceptance criterion for NPV is quite
straightforward; when the NPV is greater than zero, the project will be accepted, otherwise, the project
has to be rejected.
In this study, the system life expectancy is defined through the system components lifespan and
maintenance. the feasibility calculations were performed for two scenarios with lifespan over 25 years.
The lifespan was chosen according to the evacuated tube’s expected life of 25 years, with some literature
even expecting a lifespan of 20 years. The energy saving over 25 years was defined through forecasting
the amount of electrical energy that would be saved from the solar cooling system of its operation based
on the local distribution companies in Jordan. Operating and maintenance cost (O and M) percentage
is defined through the changed costs for operating and maintaining the system based on the lifetime
of the system. In addition, the annual inflation in O and M cost is defined through the percentage
of inflation in the operation and maintenance costs per annum. The operating cost is mainly used to
run the auxiliary components of the system; dry coolers, heating, cooling, and chilled water pumps.
Figure 9shows the share of the auxiliary power consumption components of the absorption system.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 11 of 17
For assessing the financial feasibility of the system some financial metrics were used in this
study; namely the Net Present Value (NPV) and payback period. Net Present Value (NPV) is defined
as the difference between the present value of cash inflows and the present value of cash outflows.
NPV is used to analyse the profitability of a projected investment. The acceptance criterion for NPV
is quite straightforward; when the NPV is greater than zero, the project will be accepted, otherwise,
the project has to be rejected.
In this study, the system life expectancy is defined through the system components lifespan and
maintenance. the feasibility calculations were performed for two scenarios with lifespan over 25
years. The lifespan was chosen according to the evacuated tube’s expected life of 25 years, with some
literature even expecting a lifespan of 20 years. The energy saving over 25 years was defined through
forecasting the amount of electrical energy that would be saved from the solar cooling system of its
operation based on the local distribution companies in Jordan. Operating and maintenance cost (O
and M) percentage is defined through the changed costs for operating and maintaining the system
based on the lifetime of the system. In addition, the annual inflation in O and M cost is defined
through the percentage of inflation in the operation and maintenance costs per annum. The operating
cost is mainly used to run the auxiliary components of the system; dry coolers, heating, cooling, and
chilled water pumps. Figure 9 shows the share of the auxiliary power consumption components of
the absorption system.
Figure 9. Percentage share of the auxiliary power consumption components of the absorption system.
The solar dry cooler (maximum power consumption 7.49 kW) was used to serve a uniform
temperature from the hot water circuit. The solar dry cooler is turned on when the hot water
temperature from the solar field exceeds 95 °C and turned off when the hot water temperature falls
below 85 °C. The relative low set points for activating the solar dry cooler also contribute to a higher
electrical consumption of the solar dry cooler. The reject-heat pump with an auxiliary power
consumption of 3 kW is connected with heat sinks for the absorber and condenser. The dry cooler of
the condenser has an auxiliary power consumption of 2.47 kW and the chilled water pump has a
power consumption of 2.2 kW. Furthermore, 1% of the auxiliary power consumption was used to run
the control boxes for operating the system actuators to a specified and adjustable sequence of
operation depending on the operating mode.
The results of the Discount Cash Flow financial analysis are illustrated through Figures 10–12.
In this study, the interest rate is assumed to be 6%, which is a suitable interest rate in a local
commercial bank in Jordan. Therefore, a discount rate of 6% is used in the Discount Cash Flow
analysis to determine the present value of future cash flows.
Figure 9.
Percentage share of the auxiliary power consumption components of the absorption system.
The solar dry cooler (maximum power consumption 7.49 kW) was used to serve a uniform
temperature from the hot water circuit. The solar dry cooler is turned on when the hot water
temperature from the solar field exceeds 95
◦
C and turned offwhen the hot water temperature
falls below 85
◦
C. The relative low set points for activating the solar dry cooler also contribute to a
higher electrical consumption of the solar dry cooler. The reject-heat pump with an auxiliary power
consumption of 3 kW is connected with heat sinks for the absorber and condenser. The dry cooler
of the condenser has an auxiliary power consumption of 2.47 kW and the chilled water pump has a
power consumption of 2.2 kW. Furthermore, 1% of the auxiliary power consumption was used to run
the control boxes for operating the system actuators to a specified and adjustable sequence of operation
depending on the operating mode.
The results of the Discount Cash Flow financial analysis are illustrated through Figures 10–12.
In this study, the interest rate is assumed to be 6%, which is a suitable interest rate in a local commercial
Appl. Sci. 2020,10, 2418 12 of 17
bank in Jordan. Therefore, a discount rate of 6% is used in the Discount Cash Flow analysis to determine
the present value of future cash flows.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 12 of 17
As shown in Figure 10, the absorption cooling system is deemed as feasible for a COP of 0.79 as
claimed by the manufacturer over a lifespan of 25 years. The net present worth is equal to +185,070
JD and the payback period is equal to 10 years. However, the feasibility study of the absorption
cooling system under real measurements over four summer months (May 2015–August 2015) with
an average COP of 0.32 shows that the system is not feasible, as shown in Figure 11. For the observed
cooling capacity, the net present value was equal to −137,684 JD with a payback period of 44 years
which exceeds the expected lifespan of the project.
Figure 10. Absorption cooling system cash flow diagram with a COP of the absorption chiller of 0.79.
Figure 11. Absorption cooling system cash flow diagram with an average observed COP of the
absorption chiller of 0.32.
Figure 10.
Absorption cooling system cash flow diagram with a COP of the absorption chiller of 0.79.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 12 of 17
As shown in Figure 10, the absorption cooling system is deemed as feasible for a COP of 0.79 as
claimed by the manufacturer over a lifespan of 25 years. The net present worth is equal to +185,070
JD and the payback period is equal to 10 years. However, the feasibility study of the absorption
cooling system under real measurements over four summer months (May 2015–August 2015) with
an average COP of 0.32 shows that the system is not feasible, as shown in Figure 11. For the observed
cooling capacity, the net present value was equal to −137,684 JD with a payback period of 44 years
which exceeds the expected lifespan of the project.
Figure 10. Absorption cooling system cash flow diagram with a COP of the absorption chiller of 0.79.
Figure 11. Absorption cooling system cash flow diagram with an average observed COP of the
absorption chiller of 0.32.
Figure 11.
Absorption cooling system cash flow diagram with an average observed COP of the
absorption chiller of 0.32.
As shown in Figure 10, the absorption cooling system is deemed as feasible for a COP of 0.79 as
claimed by the manufacturer over a lifespan of 25 years. The net present worth is equal to +185,070 JD
and the payback period is equal to 10 years. However, the feasibility study of the absorption cooling
Appl. Sci. 2020,10, 2418 13 of 17
system under real measurements over four summer months (May 2015–August 2015) with an average
COP of 0.32 shows that the system is not feasible, as shown in Figure 11. For the observed cooling
capacity, the net present value was equal to
−
137,684 JD with a payback period of 44 years which
exceeds the expected lifespan of the project.
Appl. Sci. 2020, 10, x FOR PEER REVIEW 13 of 17
Table 3 summarizes the results in the analysis in terms of the financial metrics chosen for the
evaluation of the feasibility of the system.
Table 3. Summary of the economic analysis of the solar absorption for the claimed and the observed
results.
Parameter Values for a COP = 0.79 Values for a COP = 0.32 (Observed)
Capital cost, JD 243,000
Maintenance cost, JD 1% of CC, each 5 years with an increment of 0.5%
Annual operating cost (Auxiliary components), JD 5737 5737
Annual save (electricity), JD 41,772 16,524
Annual saving (CO₂ reduction), JD 742 300
Net present value, JD 185,070 −137,684
Payback period, years 10 44
Rate of return 14.31% 0.82%
Levelized Cost of Electricity (LCOE), JD/kWh 0.65 1.65
The simple (solid lines) and discounted (dashed lines) payback periods for the claimed COP =
0.79 (blue lines) and the observed COP = 0.32 (red lines) are shown graphically in Figure 12.
Figure 12. Simple (solid lines) and discounted (dashed lines) payback periods for the claimed COP =
0.79 (blue lines) and the observed COP = 0.32.
One of the main drawbacks of the applying the payback period method is that it does not take
into account several key factors including the time value of money, thus the discounted payback
period is considered in this study. As shown in Figure 12, the discount payback period increased
from 7 to 23 years and from 9 to 44 years for the simple and discounted payback techniques,
respectively. Moreover, the absorption cooling system is considered as infeasible economically with
a payback period exceeding the system span life for the real observed cooling capacity.
In addition, a part of the cost analysis of the absorption chiller system was performed according
to the levelized cost of electricity (LCOE). The LCOE is calculated by dividing the net present value
Figure 12.
Simple (solid lines) and discounted (dashed lines) payback periods for the claimed
COP =0.79 (blue lines) and the observed COP =0.32.
Table 3summarizes the results in the analysis in terms of the financial metrics chosen for the
evaluation of the feasibility of the system.
Table 3.
Summary of the economic analysis of the solar absorption for the claimed and the
observed results.
Parameter Values for a
COP =0.79
Values for a COP =0.32
(Observed)
Capital cost, JD 243,000
Maintenance cost, JD 1% of CC, each 5 years with an increment of 0.5%
Annual operating cost (Auxiliary components), JD 5737 5737
Annual save (electricity), JD 41,772 16,524
Annual saving (CO2reduction), JD 742 300
Net present value, JD 185,070 −137,684
Payback period, years 10 44
Rate of return 14.31% 0.82%
Levelized Cost of Electricity (LCOE), JD/kWh 0.65 1.65
The simple (solid lines) and discounted (dashed lines) payback periods for the claimed
COP =0.79
(blue lines) and the observed COP =0.32 (red lines) are shown graphically in Figure 12.
One of the main drawbacks of the applying the payback period method is that it does not take
into account several key factors including the time value of money, thus the discounted payback period
is considered in this study. As shown in Figure 12, the discount payback period increased from 7
to 23 years and from 9 to 44 years for the simple and discounted payback techniques, respectively.
Appl. Sci. 2020,10, 2418 14 of 17
Moreover, the absorption cooling system is considered as infeasible economically with a payback
period exceeding the system span life for the real observed cooling capacity.
In addition, a part of the cost analysis of the absorption chiller system was performed according to
the levelized cost of electricity (LCOE). The LCOE is calculated by dividing the net present value of the
total cost of absorption chiller system and operating the power generating asset by the total electricity
saved over its lifetime. The LCOE values of the system are equal to 0.65 JD/kWh and 1.65 JD/kWh
when the system operates at claimed COP of 0.79 and observed COP of 0.32, respectively. When taking
into account the electricity tariffof 0.27 JD/kWh, it is obvious that the absorption chiller system is not
feasible economically.
4.4. CO2Emissions Reduction
For the calculation of the total CO
2
emission reduction, it is important to know the emission factors.
The emission factor used in this study was derived based on the numbers provided for Mediterranean
cities that carried out their sustainable energy action plan with the only exception of the electricity
emission factor, which is a characteristic of the country [
30
]. It was not possible to acquire the electricity
emission factor for Jordan directly from the Ministry of Energy and Mineral Resources or any of the
utilities servicing the country. Therefore, the utilization of available statistical energy data from the
Ministry of Energy and Mineral Resources [
31
] was considered the best approach. Using the Energy
data of 2015 and the energy production from different sources including renewable energy, as shown
in Table 4, the Electricity Emission Factor (EEF) was calculated.
Table 4.
Electrical energy production shares from different sources including renewable energy
resources in Jordan [31].
Source GWh CO2Factor kg/kWh Emission (Tons)
Natural gas 9211 0.4 3,684,400
Heavy fuel oil 6644 0.7 4,650,800
Diesel 2974 0.6 1,784,400
Renewable 184 0 0
Total 19,013 - 10,119,600
The main source of electricity generation in Jordan is the natural gas which has an emission
factor of 0.4 kg/kWh, followed by heavy fuel oil with an emission factor of 0.7 kg/kWh. The average
Electricity Emission Factor in Jordan for the year 2015 is calculated by using Equation (4), and it was
equal to EEF =0.54 kgCO2/kWh
EEF =CO2Emission (kg)
Electrical energy generated (kWh)=10,120 ×106kg CO2
19,013 ×106kWh (4)
The electrical energy (kWh) saved by operating the absorption chiller was compared against
operating the conventional vapor compression chiller with a COP of 2.5 which corresponds to
19,980 kWh in electricity savings. Thus, for the operating with COP of 0.32, the reduced CO
2
emissions
is equal to 10,789 kg, as shown in Equation (5).
Reduced CO2emission =EEF ×Saving in electrical energy =0.54kg CO2
kWh ×19,980 kWh (5)
Also, the reduction in CO
2
emissions is equal to 26,500 if the system reaches the claimed COP of
0.79. The annual savings for the reduction of CO
2
emissions with an assumption of 28
JD
ton of CO2
was
equal to 300 JD and 742 JD for COPs of 0.32 and 0.79, respectively.
Appl. Sci. 2020,10, 2418 15 of 17
5. Conclusions
Using solar power for the cooling and heating of buildings is a milestone in the search for
environment-friendly technologies in the energy sector. Four solar absorption cooling systems with a
nominal cooling capacity of 530 kW were installed in four sites in Jordan. The focus of the research was
on the pilot system at the German Jordanian University campus. The system has a capacity of 160 kW
for cooling and a 50 kW for heating. With the installed systems, Jordan is the first developing country
to use solar thermal energy to cool buildings. The aim of these systems was not only to reduce cooling
power consumption, but also to serve as a reference for researchers and experts in absorption chillers,
as it is the first of its kind to be implemented in Jordan, the region, and among developing countries.
An economic feasibility study was carried out for the absorption system taking the environment effect
of the reduction of CO
2
emissions into account. This study was based on an evaluation of the solar
thermal cooling system within four months of operation between May and July 2015.
The system was economically evaluated based on the observed cooling capacity results with a
COP of 0.32, and compared with the claimed COP of 0.79 regardless of the operating conditions. Several
techniques were implemented to evaluate the overall economic viability in-depth such as present worth
value, internal rate of return, payback period, and levelized cost of electricity. The aforementioned
economic studies showed that the absorption cooling system is deemed as not feasible for the observed
COP of 0.32 over a lifespan of 25 years. The net present value was equal to
−
137,684 JD and there was
a payback period of 44 years, which exceeds the expected lifespan of the project. Even for an optimal
operation of COP =0.79, the discounted payback period was equal to 23 years and the LCOE was
equal to 0.65 JD/kWh.
The survey shows that there are several weaknesses for applying solar thermal cooling in
developing countries, such as the high cost of these systems and, more significantly, the lack of
experience for such systems. The solar thermal cooling systems currently installed in Jordan were
either planned, built, and monitored by companies that specialize in solar thermal cooling, or were
scientifically supported by a research institution and they were being evaluated via monitoring at the
beginning of their operation.
From this perspective, the solar thermal cooling systems currently installed are not the
technologically-possible optimum. There is significant potential for reducing costs and/or increasing
performance through technological improvements mainly at the system level for overall system
optimization. The introduction of a more advanced control through the absorption chiller components
will increase operational efficiency, improve the cooling capacity, and contribute to the reduction of
CO
2
emissions. The main component in solar thermal cooling systems is the chiller and the most
relevant controlled parameter is the hot water inlet temperature and mass flow. Optimization between
high water temperature to the generator should be achieved, to increase the cooling capacity of the
absorber, while preventing possible pump damage in the case of crystallization. The improvement of
this advanced technology requires higher level of process control and professional expertise.
Author Contributions:
Conceptualization, M.J.; methodology, M.J. and M.A.-A.; formal analysis, M.J. and A.A.;
investigation, M.J. and A.A.; resources, N.B. and M.A.-A.; data curation, M.A.-A. and A.A.; writing—original
draft preparation, M.J. and N.B.; writing—review and editing, M.J., M.A.-A. and Z.D.; supervision, M.J. and N.B.
All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.
Conflicts of Interest: The authors declare no conflict of interest.
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