1. Design of Thermal
Systems
MR. S. V. YADAV
ASSISTANT PROFESSOR
DEPARTMENT OF MECHANICAL ENGINEERING
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2. Introduction
 Engineering- concise oxford dictionary, defines engineering as “the
application of science to the design, building and use of machines,
construction etc
 Engineering originates from Latin word ‘injeniare’. That means,
‘contrive’ and not from word engine
 Analysis, design, fabrication, sales, marketing, research and
development of systems are all part of engineering.
 We emphasize on system design in this course
 System: A collection of components with interrelated performance
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3. Introduction….contd
 Even this definition needs to be strengthened out because a large
systems like thermal power plant is made of several subsystems
 Our focus and our attention to on energy systems.
 Process of designing and fabricating systems has been
developed and used for ages: the existence of bridges, highways,
automobiles, airplanes, super computers, data centres
 However the evolution of these systems has taken a lot of time
and has been costly affair.
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4. Introduction….contd
 The former goal was to design, fabricate and use a system regardless of
whether it was the best one.
 Improved systems were designed only after break even was achieved in
many cases. Optimization was considered as a costly add-on
 The key point is there are several ways of accomplishing the same task.
 Again some are better than others
 Suppose we want to join sheets of paper. There are several ways of
doing this. Using a stapler, bell clip or simply binding the sheets are
some of the ways.
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5. Introduction….contd
 Design of complex systems requires large calculations often
repetitively for various combinations of the design variables.
 Fortunately, during the last forty years, we have seen really big
improvements in computers and computations.
 Engineering design has indeed benefited greatly from that
revolution. Better systems can now be designed by analysing
various options in a short time.
 We see that the desktops/laptops today are far superior
compared to those in past and cost is lower.
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6. Design
 What is Design?
 Design: It is essential elements in engineering education and practice
 Why design and optimization is required?
 What is Optimization?
 Optimization: It is a crucial need to Optimize the systems in practical
applications.
 Examples of thermal Systems: Manufacturing, Energy systems, Cooling
of electronic equipment's, refrigeration, Environmental problems, I. C.
Engines, heat transfer equipment's etc
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7. Design…Contd
 Importance of design and optimization for industries
 Industries growth and survival
 Change in industries of thermal fields
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8. Engineering Design
 Design of individual components or design of systems.
 Difference between design and other activities like analysis and
synthesis.
 Design perception changes from person to person.
 The process by which such new, different or improved solutions
are derived and applied to engineering problems is termed as
Design.
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9. Fig. Analytical results for a) developed fluid flow in a circular pipe
b) Steady State one dimensional heat conduction in flat plate
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10. Fig. An electronic component being cooled by forced convection and by heat
pipe
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11. Fig. the casting process in an enclosed region
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12. Synthesis for Design 12

13. Selection Vs Design
FIGURE Common types of heat exchangers. (a) Concentric pipe parallel-flow,(b) concentric pipe counter-
flow, (c) cross-flow with unmixed fluids, (d) fin-tube compact heat exchanger cores, (e) shell-and-tube.
(Adapted from Incropera, F.P. and Dewitt, D.P., 1990.)
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14. Steps followed in the
conception, evaluation and
execution of a plan of
engineering undertaking
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15. Plan of engineering undertaking
 The above flow chart shows the typical steps followed in the
conception, evaluation and execution of a plan of engineering
undertaking.
 The rectangular boxes indicates actions and may represents
considerable efforts and expenditure in the case of large
projects.
 The diamond boxes represents decision e.g. whether to
continue the project or drop it.
 System design anyway will be studied in details in this
course along with optimization
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16. Plan of engineering undertaking…
Contd
 The other individual non- design activities that find a place in
the flow chart:
 Needs analysis
 Engineers are concerned with the application of technology to
satisfy human needs.
 Essence of engineering is characterised by the design process,
in which resources are transformed into needed systems or
devices.
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17. Plan of engineering undertaking…
Contd
 Transformation starts with the recognition of some need.
Device may be simple or exceedingly complex
 Need : To join sheets of paper
 Result.....?
 Need : to transport people from homes to their places of work.
 Result....?
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18. Need or opportunity
 Defining a need or opportunity is always the first step in an
engineering undertaking because it provides the stimulus to develop
a product or system.
 Need refers to a specific requirement and implies that a suitable item
is not available and must be developed for the desired purpose.
 Opportunity is the recognition of a chance to develop a new product
that may be superior to existing ones or less expensive. It may also
be an item for which the market is expected to develop as it becomes
available.
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19. Need
 Discovered through service conducted
by sales division and direct consumer
interaction with salesperson
 Problems and limitations of existing
systems
 example 1TB hard disk
requirement, RAM, Abs, Airbag, Co
mputer controlled fuel
injection, streamlined body in
automobiles, HD TV
Opportunity
 Increasing quality of current systems
and reducing cost
 Use of new lightweight materials
 Replace metal casting by plastic for
ceramic material in electronic
equipment
 Similarly in sport equipment
 Example laptops, fiber optics cable,
compact disc player, microwave
oven, Apple iPod or iPhone
 R&D team will always work on
opportunity
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20.  A new product may always be an opportunity. But if a company does not
expand its line of products, business is likely to decline.
 Example: Geared scooters are fossilized now.
 Thus the introduction of a new product is also a need.
 Needs or opportunities lie in the renovation or expansion of facilities to
manufacture or distribute on current product.
 Opportunity also arises when sale of a product manufactured by competition
is rising and market conditions seems favorable (example success of Ford
Figo).
 A new product may be developed intentionally or accidentally sometimes
products are also discovered accidentally.
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21. Evaluation and Market Analysis
 To profit in any Engineering undertaking, evolution for economic viability is a
very important.
 It is always necessary to determine,
 how big market is
 what price range it bear
 possible expenses to complete the concept
 type of consumer to target like individual, organizations or industries
 information regarding price consumption level
 desired characteristics of product
 All this information could be gathered through surveys, telephone or
Individual contact, interactions with product outlets, sales organization and
inputs from consumer groups.
 The marketing division can determine the anticipated volume of sales and
effect of price on sales.
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22. Feasibility and chances of success
 Very important to check whether enterprise is feasible and what are chances of
success.
 These considerations are usually brought in early in the project, though the
inputs from R&D, design may be needed to make a reliable judgement.
 Measure of success:
 This would depend on nature of enterprise and product under consideration.
 If return on investment is good, undertaking a successful and it is the criteria of
most of Engineering companies.
 sometime other than money like pollution and environmental requirements due to
government policies may be crucial factor.
 Ex. use of cooling Towers instead of water for cooling of condenser in company,
refrigerants like CFC’S are banned due to depletion of ozone, for chemical plants
waste disposal, some safety aspects etc.
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23. Feasibility and chances of success
 Chances of success:
 Success depends on many events in the future that can't be predicted
with certainty.
 Its probabilistic analysis of various items that are involved in enterprise
like financing decision, R&D, manufacturing, testing, government
approvals, sales, Advertising and Marketing.
 The probability of success must be considered over the entire duration
of project and may be expressed in terms of probability of achieving
the chosen measure of success.
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24. Feasibility
 Another important consideration is whether the enterprise is possible at all.
 If it is feasible showing indication, then only we proceed.
 Sometimes infeasible reasons may be technical or non-technical
 like if rate of return is small
 chances of success are not satisfactory
 technically non availability of material, design for fabrication of system
 lack of investment capital, industrial site and facilities, labor, transportation, waste
disposal facility
 Issues like safety, environmental and other regulations like for nuclear
Industries face many optical from regulatory bodies opposition from local
group.
 for steel plant, bad transport facility more expenses to get product into the
market.
 so for all this some modification or alternatives are required and if it still
invisible the project is terminated.
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25. Engineering Design
 After all detailed market analysis, evolution, chances of success and
feasibility, engineering design of system is initiated.
 Design will determine the specification of various components that is system
hardware and range of operating conditions.
 Design involves a consideration of technical details of basic concepts and
creation of new or improved process or system for specified task.
 Design process starts with basic concepts and models and analysis of
various constituents of system, synthesizes information on materials, existing
system and results from different model, evaluate performance and
communicate these design specifications for fabrication and prototype
development.
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26. Research and Development
 Frequently the information needed for design and optimization is not readily
available, so R & D is employed to obtain this information from literature on
relevant processes and system and from independent detailed investigations
of basic aspects involved.
 R & D people normally interact with most engineering activities within
company and provide input at various stages of production, or system
development.
 All the department discuss the problem with R & D for solving or investing
new things. Thus R&D group devotes it’s efforts in developing new
techniques for improving existing processes and to come up with new ideas
that may be applied to develop a new product.
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27. Need for Optimization
 It's not sufficient to develop a workable system that performs desired task
within constrains life safety, environment, economic and other consideration.
 Due to world-wide competition and need to increase efficiency it has become
essential to optimize the process in order to maximize or minimize a chosen
variable that is called objective function and may be related quantities such
as Profit, cost, product quality and output.
 Today the survival of given product is largely a function of its performance per
unit cost.
 It is necessary to seek an optimal design that will consume least amount of,
this is closely linked with overall efficiency of system.
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28. Fabrication, Testing & Production
 The final stages in Engineering Enterprise before proceeding to
advertising, promotion, sale are fabrication and testing a prototype of
design system and production in desired quantities for sale.
 The output from design process must be communicated to appropriate
technical facilities in order to fabricate, operate and test system.
 The communication may include, engineering drawing with dimensions,
tolerances, design specifications, particulars of selected components,
range of operating conditions, chosen materials, power and space
requirement, detail of waste disposal, energy disposal, system control
strategy and safety measures etc.
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29. Testing of Prototype
 Once prototype is obtained, it is subjected to extensive testing over the
expected range of operating conditions.
 Accelerated test may be carried out to study reliability of the system over its
expected life and worse conditions are tested.
 The test on prototype are used to confirm and establish the design
specifications to ensure that the desired task is being performed satisfactorily.
 It gives validation and improve the mathematical model of the system
characteristics.
 The prototype is also used for improvements in the design based on actual
tests and measurements.
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30. Production of Product/System
 Following to prototype development and testing, the system goes into
production.
 Existing facilities are modified, or new ones procured to mass produce the
product or system
 Economic considerations play an important role in the development of
production facilities needed.
 The mass production of the product is also closely coupled with its marketing
which involves advertising, promotion and sales.
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31. Thermal Systems
 Basic characteristics:
 What we mean by a component, a subsystem, a system, and a process?
 Different types of systems arise in engineering design depending on the main
features that characterize these systems.
 E.g. electronic systems, mechanical systems, chemical systems, structural
systems
 Systems that involve a consideration of thermal sciences to a significant
extent in their analysis and characterization are termed as thermal systems.
 thermal systems arise in many diverse fields of engineering, such as
aerospace engineering, manufacturing, power generation, and air
conditioning.
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32. Analysis of thermal systems
 It is often complicated because of the complex nature of fluid flow and of
heat and mass transfer mechanisms that govern these systems.
 Following are some of the characteristics that are commonly encountered in
thermal systems and processes:
 1. Time-dependent
 2. Multidimensional
 3. Nonlinear mechanisms
 4. Complex geometries
 5. Complicated boundary conditions
 6. Coupled transport phenomena
 7. Turbulent flow
 8. Change in phase and material structure
 9. Energy losses and irreversibility
 10. Variable material properties
 11. Influence of ambient conditions
 12. Variety of energy sources
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33. Analysis of thermal systems
 Algebraic Equations:
 Ordinary Differential Equations:
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34. Analysis of thermal systems
 Partial Differential Equations:
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35. Types & examples of
thermal systems
 Manufacturing and Materials
Processing Systems
 Fig. a) Continuous Casting
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36. Types & examples of
thermal systems
 Manufacturing and Materials
Processing Systems
Fig. b) Plastic Screw Extrusion
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37. Types & examples of
thermal systems
 Manufacturing and Materials
Processing Systems
 Fig. c) Optical Fiber Drawing
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38. Types & examples of
thermal systems
 Manufacturing and Materials
Processing Systems
 Fig. d) Hot Rolling
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39. Energy systems
 Cooling Systems for Electronic
Equipment
 Fig. a) Solar Energy
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40. Energy systems
 Cooling Systems for Electronic
Equipment
 Fig. b) Nuclear Energy
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41. Cooling Systems for
Electronic Equipment
 Fig. a) Forced air cooling
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42. Cooling Systems for
Electronic Equipment
 Fig. b) Liquid Immersion
cooling
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43. 43

44. Environmental and
Safety Systems
 Fig. Systems for heat rejection
from power plant
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(b) natural draft cooling tower.
(a) natural lake as cooling pond

45. Environmental and
Safety Systems
 Flow and temperature due to
fire in a room with an opening
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46. Transportation
systems
 Thrusting systems for aircraft
Propulsion
 Turbojet engine with and
without afterburner
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47. Transportation
systems
 Reciprocating internal
combustion engine
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48. Fluid Flow Systems &
Equipment's
 Piping network for flow system
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49. Heat Transfer
Equipment
 Heat Exchangers, Condensers,
boilers, furnaces, ovens,
heaters
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50. Thank you…!
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