thermodynamic, heat engine,

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Ministry of Higher Education & Scientific Research
Sulaimani Polytechnic University (SPU)
Technical College of Engineering
Mechanical Department
Third Stage – First Semester
Academic Year 2022-2023
EXPERIMENT
NO.1
Prepared by: Mohammed Obed Aziz
Heat Engines

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Table of Contents
Objective:..............................................................................................................3
Introduction:..........................................................................................................3
Heat Engine Efficiency.........................................................................................4
Types of Heat Engine............................................................................................5
Application:...........................................................................................................6
Heat Pump and Refrigerator: ................................................................................8
Discussion:..........................................................................................................10
Reference: ...........................................................................................................10

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Table of figures
Figure 1 working of heat engine...........................................................................4
Figure 2 external combustion engine....................................................................5
Figure 3 internal combustion engine ....................................................................5
Figure 4 steam train...............................................................................................6
Figure 5four-stroke cycle......................................................................................6
Figure 6 The heat pump cycle...............................................................................7
Figure 7 steam power plant...................................................................................7
Figure 8 refrigerant cycle......................................................................................8
Figure 9 heat pump cycle......................................................................................9

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Experiment number: 1
Experiment name: heat engines
Objective:
In this experiment we know
• What is heat engine?
• Type of heat engine.
• How can use heat engine in application?
• What is efficiency?
• How can increase the efficiency?
• And what is the thing can reduce the efficiency?
• Heat pump, air condition and refrigerator
• Cycle of heat pump and refrigerator
Introduction:
A heat engine is a device that turns heat into mechanical energy that can then be
utilized to do work. It accomplishes this by lowering the temperature of a working
substance from a higher state temperature. A heat source produces thermal
energy, which raises the temperature of the working substance. The working
material produces work in the engine's working body while transferring heat to a
colder sink until it reaches a low-temperature state. Using the qualities of the
working substance, some of the thermal energy is turned into work throughout
this process. Any system with a non-zero heat capacity can be used as the working
substance, however, it is most commonly a gas or liquid. Some heat is generally
lost to the environment during this process and is not converted to work. Friction
and drag also render some energy ineffective.

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Figure 1 working of heat engine
Heat Engine Efficiency
Let us derive an expression for the efficiency of a heat engine. We can define heat
engine efficiency as:
𝜂 = 𝑊/𝑄1
Where,
W = Work done by the engine
𝑄1= Heat taken from the source
After each cycle, the engine returns to its initial state, so,
∆𝑈 = 0
So from the figure1, it is clear that,
𝑊 = 𝑄1 − 𝑄2
Hence the heat engine efficiency is:
𝜂 =
𝑄1 − 𝑄2
𝑄1
𝜂 = 1 −
𝑄2
𝑄1
So for Q2 = 0 efficiency will be 100% but, in actual, this is not possible because
there will be some loss of energy in the system. Hence, for every engine, there is
a limit for its efficiency. The efficiency is maximum for a reversible engine such
as Carnot heat engine.

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Figure 2 external combustion engine
Figure 3 internal combustion engine
Types of Heat Engine
Following are the two types of heat engines:
• Internal combustion engine (Piston engine, Gas turbine, Jet engine)
• External combustion engine (nuclear reactors like CANDU reactor,
pressurized water reactor, coal-fired power plant, natural gas power plant)
External combustion engine:
In these heat engines, the fuel burns outside and away from the main engine,
where force and motion are produced. A steam engine is an example of an
external combustion engine.(as shown in figure2)
Internal combustion engine:
In these heat engines, the fuel burns inside the cylinder. A car engine is an
example of an internal combustion engine.
The internal combustion engine is more efficient than the external combustion
engine as there is no energy wasted during heat transfer between the boiler and
the cylinder.(as shown in figure3)

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Figure 4 steam train
Figure 5four-stroke cycle
Application:
1. Steam engine: The steam engine and steam turbines are two of the most
well-known examples of a heat engine, and the invention of the steam
engine was an important historical event in the industrialization of society.
2. Internal Combustion Engine: The internal combustion engine works based
on the Otto cycle described above, with spark ignition used for gasoline
engines and compression ignition used for diesel engines.

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Figure 6 The heat pump cycle
Figure 7 steam power plant
3. Heat Pumps, Air Conditioners and Refrigerators: Heat pumps, air
conditioners and refrigerators all work on a form of heat cycle too, although
they have the different goal of using work to move the heat energy around
rather than the reverse.
4. Power Plants or Power Stations: Power stations or power plants are really
just another form of heat engine, whether they create heat using a nuclear
reactor or by burning fuel.

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Figure 8 refrigerant cycle
Heat Pump and Refrigerator:
We have read about heat engines that convert heat energy into work and their
application in various fields of thermodynamics. Can we think of a device that
is the opposite of a heat engine, i.e., a device that helps convert work into heat?
In this section, we will learn about the refrigerator and heat pump that works on
the opposite principle of a heat engine.
➢ Refrigerator
Working
In the refrigeration cycle, there are five basic components: a fluid refrigerant, a
compressor, a condenser coil, an evaporator coil, and an expansion device. The
compressor constricts the refrigerant vapor, raising its pressure, and pushes it into
the coils on the outside of the refrigerator. When the hot gas in the coils meets the
cooler air temperature of the kitchen, it becomes a liquid. Now, in liquid form at
high pressure, the refrigerant cools down as it flows into the coils inside the
freezer and the fridge. The refrigerant absorbs the heat inside the fridge, cooling
down the air. Lastly, the refrigerant evaporates and then flows back to the
compressor, where the cycle repeats itself.

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Figure 9 heat pump cycle
➢ Heat Pump
A heat pump is a mechanical compression cycle that can be reversed to
either heat or cool a controlled space.
Working
A typical heat pump consists of two parts: an indoor unit called an air handler and
an outdoor unit similar to an air output unit. A compressor circulates a refrigerant
that absorbs and releases heat as it travels between these two units. Here, the
working fluid or the refrigerant (in its gaseous state) is pressurized by a
compressor and circulated through the system. The process of compression makes
the fluid hotter. The hot and pressurized vapor on the discharge side of the
compressor is cooled in a heat exchanger called a condenser until it condenses
into a high pressure, moderate temperature liquid. The pressure of the condensed
fluid is reduced using a pressure-lowering device such as a capillary tube or an
expansion valve. The temperature of the low-pressure liquid is increased in a heat
exchanger, after which the refrigerant is made to return to the compressor, and
the cycle is repeated.

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Discussion:
We wanted to reduce loss and increase efficiency that we know in car engine
work we increase tame thing to increase efficiency and reduce loss in result we
increase turbo for example that helpful for engine work and another thing for
instance EGR, GDI, ECU that connected by injector still now its InProgress,
Another thing that we know is two things in heat engine that have a opposite
work that’s heat pump and heat engines, A heat engine is a device that converts
heat into mechanical energy. It accomplishes this by moving an active substance
from a higher temperature to a lower temperature.
A heat pump is essentially a heat engine that operates in reverse. In other words,
a heat pump is used to pump and convert heat energy to a thermal source. It is
commonly used to transfer thermal energy by trapping heat from a cold
environment and transferring it to a warmer instance.
Reference:
✓ Kondepudi, D., & Prigogine, I. (2014). Modern thermodynamics: from heat engines to
dissipative structures. John Wiley & Sons.
✓ De Vos, A. (1985). Efficiency of some heat engines at maximum‐power conditions. American
Journal of Physics, 53(6), 570-573.
✓ Sauer, H. J., & Howell, R. H. (1983). Heat pump systems.
✓ Chua, K. J., Chou, S. K., & Yang, W. M. (2010). Advances in heat pump systems: A
review. Applied energy, 87(12), 3611-3624.

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