1. Masdar Institute of Science and Technology
ESM501 . Systems Architecture . Fall 2014
Multi-Stage Flash Distillation System Integrated with Solar Energy
Reverse Engineering of System Form
Mouza M. Al Kaabi
mmalkaabi@masdar.ac.ae

2. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 2
TABLE OF CONTENTS
1. Introduction ..........................................................................................................................................3
1.1. Motivation and Relevance to the UAE..........................................................................................3
1.2. Water-Energy Nexus as System Context.......................................................................................4
1.3. System Boundary around Multi-Stage Flash Desalination............................................................5
2. Mutli-Stage Flash Desalination Form modeling....................................................................................6
2.1. Modeling Strategy.........................................................................................................................6
2.1.1. Decompositional View of MSF..............................................................................................6
2.1.2. Decompositional View Of PTC ..............................................................................................9
2.1.3. Structural View of MSF System...........................................................................................10
2.2. DSM of MSF System....................................................................................................................11
3. Conclusion...........................................................................................................................................12
4. Refrences ............................................................................................................................................13

3. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 3
1. INTRODUCTION
1.1.Motivation and Relevance to the UAE
Civilizations throughout history have been known to establish and flourish near water sources,
and today water consumption is a valid indicator of the standard of living for any community.
Availability of water is considered a key issue for a country like the UAE, which is located in an
arid region with low and irregular rainfall and high level of evaporation. The recent developments
and the rapid urban growth, coupled with the increasing population have resulted in increased
consumption of large quantities of groundwater for irrigation, industrial and domestic usages,
leading to a 18% ground water reduction level since 2003.
UAE water resources can be classified into
conventional and non-conventional water
resources as illustrated in figure 1. The natural
resources such as surface water and groundwater
fall under the conventional water resources, while
the non-conventional water resources are
produced through artificial processes consisting of
desalinated water and treated wastewater. The
total consumption of water resources in the Emirate today exceeds 24 times its natural recharge
capacity. The desalinated water is providing for almost all the drinking water, while desalinated
water surplus is used for the artificial recharge of underground water, the aim is to increase the
current 48 hours drinking water reservoir to 90 days as a protection in case of an emergency. As
a result, the water planning and management in the UAE now combines both conventional and
nonconventional water resources. It is expected that the demand for desalinated water to almost
double by 2030. In 2010, there were eight seawater desalination plants in Abu Dhabi alone, and
more planned to be built to cover for the deficit in water supply. [1] [2] [3] [4] However, the
experience gained from the existing projects, coupled with the growing water and energy
demand, elevated the expectations in terms of optimization and innovation in constructing the
Figure 1: classification diagram of the water
resources in the UAE

4. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 4
new desalination plants, while posing the question of whether it is feasible to retrofit legacy
desalination systems for higher efficiency.
This paper will analyze the form of one of the most prevailing water desalination technologies in
the UAE; Multi-Stage Flash system, while introducing a retrofitting scheme for the legacy
architecture by linking parabolic through solar collectors as a heat source, replacing the
conventional heating component produced for gas turbines, which is connected to electricity
production in the water-energy nexus.
1.2.Water-Energy Nexus as System Context
The electricity and water production
technologies are connected, they are
coupled to create the energy-water nexus as
illustrated in figure 2. Energy-water nexus
can be defined as “system-of-systems
composed of one infrastructure system with
the artifacts necessary to describe a full
energy value chain and another
infrastructure system with the artifacts
necessary to describe a full water value
chain.” The recent economic development, and population growth has derived an increase in the
demand of water and energy, in addition to the improvement in the standards related to
increasing efficiency of the legacy systems [5]. Analyzing the architecture form of the multi-stage
flash system, will require the consideration of the context that the system fall under and interact
with. The process used for desalination system, specifically the multi-stage flash system, is
integrated with the conventional process of electricity production where both require low
pressure heating steam extracted from power plants at low cost. [6]
This paper will consider that the system to be examined is contained within the water-energy
nexus, any retrofitting in form of the desalination legacy system will be connected to the energy
production system.
Figure 2 : System context and boundary

5. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 5
1.3.System Boundary around Multi-Stage Flash Desalination
The multi-stage system is classified as a thermal process of desalination as shown in the
classification diagram in figure 3, thermal desalination accounts for 50% of the entire desalination
market, while thermal process require excessive amount of energy, the massive filed experience
in the thermal process used in desalination plants like MSF, provides a competitive production
cost compared to other desalination processes like reverse osmosis [6]. The multi-stage flash
system is constructed in cogeneration plants, where power and water are produced
simultaneously. The advantage of working with MSF is that the system provide the opportunity
to utilize renewable energy for heat addition, this paper will integrate the form of the legacy
multi-stage flash system with parabolic through solar collectors as a proposed retrofitting to
increase energy efficiency.
Figure 3 : Classification Of Desalination Systems based on process and energy sources required.

6. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 6
2. MUTLI-STAGE FLASH DESALINATION FORM MODELING
Demonstrating a system or a product in a simplified abstraction is a critical step in developing,
refining alternative solutions, design languages provide an aid to a clear an efficient
representation of the system architecture. It is significant to present system architecture in a
quality method due to the impact of system architecture on downstream issues [7].
2.1.Modeling Strategy
This paper will use unified modeling language (UML) and Systems Modeling Language (SysML) to
represent the form of the Multi-stage flash system’s architecture, in addition to the parabolic
through solar collectors. The form of an architecture consists of structure elements; which
includes classes and components. The system of Multi-stage flash and parabolic solar collectors
will be represented in diagrams, the information represented in diagrams comparing to models
are incomplete. Nevertheless, diagrams provide an abstraction of the overall system to aid the
development of alternative scheme of a desalination system integrating renewable energy
source. [8]
This paper also utilize the method of design structure matrix (DSM), to visualize and analyze the
dependencies between the decomposed components of the multi-stage flash system, while
clarifying the approach to be followed to integrate the legacy system components with the
parabolic through solar collectors. [9]
2.1.1. Decompositional View of MSF
The first step in representing the architecture form is creating the decompositional diagram, the
process of decomposing the complex system provide an abstraction the needed develop the
system. Figure 4 to figure 7 represent the main components constructing the multi-stage flash
system’s architecture, a typical multi-stage flash consists of number flash chambers, the multi-
stage flash technology requires from 20 to 25 chambers at least, as the desalination efficiency
improves with the increase in number of champers, in addition to the increase of the cost of
initial construction works and the economic return. Hence, representing the system in the
decompositional view aid in analyzing cost and efficiency of the system, while studying the
benefit gained through life-cycle properties like flexibility through reconfigurability.

7. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 7
Figure 4 : Decompositional View of Multi-stage flash system components.
Figure 5 : Decompositional View of Flash Chamber

8. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 8
Figure 6 : Decompositional View of Brine Heater
Figure 7 : Decompositional View of Deaerator

9. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 9
2.1.2. Decompositional View Of PTC
The other component to be integrated
with the multi-stage flash system is the
renewable energy source of heating; the
parabolic through collector. Figure 8
simplifies the way PTC operates, the
parabolic mirror reflects the sun radiation
into a focused point; which is the solar
radiation absorption system, consisting of
two pipes with vacuum in between, and
synthetic oil composite inside [10], the temperature at the vocal point is 70 times higher than the
normal sunlight [6]. The synthetic oil acts as a connection between the parabolic solar collector
and the multi-stage flash system at the brine heater which serve as an interface for that
connection.
The components of the PTC with their parts and properties are decomposed in figure 9, this
decomposition of the parabolic solar collector reveal the feasibility of integration of the system
as a heat source, as long as the systems can meet in a heat receiving interface; which is the brine
heater in this case.
Figure 8 : Illustration of the PTC system
Figure 9 : Decompositional View of PTC

10. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 10
2.1.3. Structural View of MSF System
The structural view represent the components of the system with the dependencies between the
components, when representing the system form, the interfaces are distinguishable in
comparison with the decompositional view. The structure view illustrated in figure 10 reveal the
structure of the system, the function of the overall system can later be mapped by identifying
the behavior of components in connection with each other. Although the structural view
illustrate the direct connection between the components, yet the amount of information that
can be extracted from the diagram is limited to the general overview of the overall dependencies.
Hence, the next step would be to map the design structure matrix to reveal the characteristics of
the system that would aid in the decision making process.
Figure 10 : Structural View of the MSF heated by MSF

11. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 11
2.2.DSM of MSF System
Design Structure matrix is representation of the structural interrelationship of system
components, using a two-dimensional format, to reveal the dependency between the
components [11]. The DSM used to describe the MSF system in figure 11 is object-based, most
of the relationships between the system components representing the form are coupled, as the
structural view presented previously, the components are connected with the main fluids
running through the system, which are the seawater, the brine and the fresh water. As the
number of components increase with the increase of the system complexity, the DSM offer an
advantage of modularity that aid in the control of emerging processes, which increase the
robustness and the resilience of the system. The multi-stage flash with the connection to
parabolic solar collectors represented here is considered a closed system, but if the system was
to be integrated with the electricity production, then the DSM can adapt with the increasing
complexity with minimal disruption [12].
Figure 11 : DSM of MSF integrating PTC

12. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 12
3. CONCLUSION
This paper provided an over view of the system architecture form of multi-stage flash system,
integrated with parabolic solar collector as a source of heat used for the desalination process.
The modeling strategy utilized the unified modeling language (UML) and Systems Modeling
Language (SysML) to represent the elements and the structure of the system, through
decomposing the different components and classes then providing an over view of the interfaces
connection in a structural view diagram. However, advanced characteristics of the system can be
identified using the design structure matrix, all the components of both multi-stage flash and the
parabolic through collector, and mapping the interrelationships in between the components.
Analyzing the form of the multi-stage flash using the previously mentioned methods, reveal a
feasible coupling between the legacy system of multi-stage flash and the use of parabolic solar
collector, or any type of other clean source of heat. Using the brine heater as an interface
between the legacy system and the renewable source.
Nevertheless, the abstract level of representation in this paper is not enough to confirm the
validation of this proposed integration between multi-stage flash and parabolic solar collectors.
The presented diagrams mapped only the system form, the following step would be to represent
the system behavior through representing the system function.

13. Engineering Systems and Management Masdar Institute of Science and Technology
Page | 13
4. REFRENCES
[1] Environment Agency - Abu Dhabi, "THE WATER RESOURCES MANAGEMENT STRATEGY FOR THE EMIRATE OF ABU DHABI
2014-2018," 3 2014. [Online]. Available: http://www.ead.ae/wp-content/uploads/2014/03/Executive-Summary-of-The-
Water-Resources-Management-Strategy-for-the-Emirate-of-Abu-Dhabi-2014-2018-Eng1.pdf. [Accessed 8 11 2014].
[2] WAM, "uae interact," UAE National Media Council, 22 3 2009. [Online]. Available:
http://www.uaeinteract.com/docs/EAD_warns_against_depletion_of_Abu_Dhabis_water_resources_within_next_50_y
ears/34877.htm. [Accessed 7 11 2014].
[3] A. Murad, H. Al Nuaimi and M. Al Hammadi, "Comprehensive Assessment of Water Resources in the United Arab
Emirates," Water Resour Manage, vol. 21, no. 1, p. 1449–1463, 2007.
[4] C. Sommariva and V. Syambabu, "Increase in water production in UAE," Desalination, vol. 138, no. 1-3, p. 173–179, 2001.
[5] W. Lubega and A. Farid, "Quantitative engineering systems modeling and analysis of the energy–water nexus," Applied
Energy, vol. 135, p. 142–157, 2014.
[6] A. Cipollina, G. Micale and L. Rizzuti, Seawater Desalination:Conventional and Renewable Energy Processes, Palermo:
Springer, 2009.
[7] M. Van Wie, P. Rajan, M. Campbell, R. Stone and K. Wood, "REPRESENTING PRODUCT ARCHITECTURE," in ASME 2003
Design Engineering Technical Conferences,Computers and Information in Engineering Conference, Chicago, 2003.
[8] T. Weilkiens, Systems Engineering with SysML/UML: Modeling, Analysis, Design, Heidberg: Morgan Kaufmann, 2008.
[9] Institute of Product Development, "dsmweb.org," Institute of Product Development, 2009. [Online]. Available:
http://www.dsmweb.org/. [Accessed 9 11 2014].
[10] A. Hegazy and M. ElMadany, "DESIGN AND EXPERIMENTAL TESTING OF A SOLAR PARABOLIC TROUGH COLLECTOR WITH
ITS TRACKING SYSTEM FOR SALT-WATER DESALINATION IN ARID AREAS OF SAUDI ARABIA," in Saudi Engineering
Conference, Riyadh, 2007.
[11] O. d. Weck, "MIT Education," 2012. [Online]. Available: http://ocw.mit.edu/courses/engineering-systems-division/esd-36-
system-project-management-fall-2012/lecture-notes/MITESD_36F12_Lec04.pdf. [Accessed 9 11 2014].
[12] T. Browning, "The Design Structure Matrix: A Tool for Managing Complexity," scientific american, 15 9 2012. [Online].
Available: http://blogs.scientificamerican.com/guest-blog/2012/09/15/the-design-structure-matrix-a-tool-for-managing-
complexity/. [Accessed 9 11 2014].
[13] A. Santhosh, A. Farid and K. Youcef-Toumi, "Real-time economic dispatch for the supply side of the energy-water Nexus,"
Applied Energy, vol. 122, p. 42–52, 2014.
[14] S. Kalogirou, "Seawater desalination using renewable energy sources," Progress in Energy and Combustion Science, vol.
31, p. 242–281, 2005.
[15] A. Khawaji, I. Kutubkhanah and J.-M. Wie, "Advances in seawater desalination technologies," ScienceDirect, vol. 221, p.
47–69, 2007.