heat engines and refrigeration presented by group 1 (class b) november, 2012
TRANSCRIPT
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HEAT ENGINES AND REFRIGERATION
Presented by
Group 1
(Class B)
November, 2012
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Outline
Heat Engines Type of Heat Engines Carnot Cycle Petrol and Diesel Engines Refrigeration Operating principle Method of Refrigeration Recent researches in Heat Engine and
Refrigeration
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Heat Engines
Systems that basically converts heat energy to mechanical energy
Harnessing their work done has been the focus of development
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Types of Heat Engines
Internal Combustion Heat Engine
External Combustion Heat Engine
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The Carnot Cycle
Heat engines cannot convert all the input energy.
The fraction converted is called the thermal efficiency
The maximum possible efficiency of a heat engine is that of a hypothetical (ideal) cycle, called the Carnot Cycle.
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Petrol and Diesel Engines
Petrol Diesel
η = 1 - 1/(rk-1) re = V1/V3
rc = V1/V2
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4-Stroke Engine
Induction Stroke Compression Stroke
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4-Stroke Engine
Power Stroke Exhaust Stroke
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Refrigeration Refrigerator is a reversed
heat engine. Heat is continuously
transferred from the cold space to the hotter surroundings.
This is a violation of the natural law of heat transfer hence energy must be put into the system.
Refrigerators are cyclic devices.
The working fluids are called refrigerants.
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Common Application
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Operation and Principle
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Method of Refrigeration
Cyclic Method
Vapour-compressi
on refrigerati
on
Vapour-absorptio
n refrigerati
on
Vapour-compres
sion cycle
Ideal vapour compression cycle
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Method of Refrigeration
Reverse carnot cycle
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Recent Advancement in Refrigeration Operations
Refrigerant decision based on criteria of safety, costs and environment protection
Refrigerant should have excellent thermodynamic properties, high chemical stability and good physical characteristics.
Substances used as refrigerants are: Ammonia refrigeration convinces with top
energy efficiency Using carbon dioxide to save energy and
money
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Recent Advancement in Refrigeration Operations
Climate-neutral cooling with hydrocarbons Water refrigeration with up to 25% potential
savings Air: fast refrigeration at low energy costs Double advantage for the environment and
corporate balance sheets