"Heat Engine" Utilization of Internal Energy PPT Courseware 2

Description

"Heat Engine" Utilization of Internal Energy PPT Courseware 2

Knowledge goal:

1. Understand the basic working principles of four-stroke gasoline engines.

2. Understand the calorific value of fuel from the perspective of energy conversion.

3. Understand the importance of the utilization of internal energy in the history of human development.

4. Understand efficiency through the conversion and transfer of energy.

1. Acquisition of internal energy:

Analysis from the perspective of energy conversion:

Through the combustion of fuel, the ______ energy inside the fuel is converted into _______ energy.

After the water boils:

Phenomenon: Cork ______; ______ has "white gas" produced.

Analysis: ________ does work on the cork, the internal energy is ____, and the temperature _________ turns it into small water droplets.

Energy conversion: _______ is converted into ______.

First stroke: ________. The intake valve ________, the exhaust valve ________, the piston moves from the ________ most to ________ of the cylinder, and the mixture of ________ and ________ is drawn into the cylinder from ________. When the piston moves to the lowest end of the cylinder, the ________ closes and the crankshaft rotates ________ turns.

Second stroke: ________. The intake valve and exhaust valve ________, the piston moves from the furthest _________ to _________ of the cylinder, the fuel mixture is _________, the temperature in the cylinder ________, and the air pressure _________. The crankshaft rotates ________ turns. In this process, ________ transforms ________.

Working principle of gasoline engine

think:

1. Among the four strokes, in which strokes does energy conversion occur?

Compression stroke: mechanical energy internal energy

Power stroke: internal energy mechanical energy

2. Which stroke gets the power?

power stroke. (The other three strokes are also called auxiliary strokes.)

3. A working cycle consists of four strokes. In each working cycle, the piston reciprocates __ times, the crankshaft and flywheel rotate ___ times, and perform ___ times of external work. The auxiliary stroke is completed by the function of the flywheel.

Class summary

1.Heat engine.

2. Internal combustion engines are divided into gasoline engines and diesel engines.

3. The similarities and differences between gasoline engines and diesel engines.

think:

1. The working process of a four-stroke gasoline engine consists of four strokes ( ).( ).( ).( ).

2. In a four-stroke gasoline engine, the ( ) stroke converts mechanical energy into internal energy, and the power stroke converts ( ) energy into ( ) energy.

3. What the gasoline engine sucks into the cylinder is ( ), and the ignition method is ( ). The diesel engine sucks into the cylinder ( ), and the ignition method is ( ).

knowledge application

1. A single-cylinder four-stroke internal combustion engine completes 40 strokes. Regarding the power and flywheel rotation, the following statement is correct ( )

A. Work 10 times, the flywheel rotates 40 times

B. Work 40 times, flywheel rotates 20 times

C. Work 10 times and the flywheel rotates 20 times

D. Work 20 times and the flywheel rotates 10 times

2 For a four-stroke gasoline engine, the crankshaft speed is 1200 rpm, then the gasoline engine does ___ times of work per second, has ___ strokes, and the flywheel rotates ___ times.

1. Classification of fuel:

Solid fuels, liquid fuels and gaseous fuels.

For example:

Firewood, coal, kerosene, gas, natural gas;

2. Chemical reactions of fuel combustion:

Energy conversion: chemical energy-internal energy/thermal energy;

Function: Provide most of the energy to humans to heat or do work;

Guess: Do different fuels of the same mass release the same amount of heat when completely burned?

3. Calorific value

The combustion of fuel is a chemical reaction. During the combustion process, the chemical energy stored in the fuel is released and converted into internal energy. Different fuels of the same mass release different amounts of heat when completely burned.

1. Definition: Refers to the heat released by the complete combustion of a certain substance per unit mass. Its symbol is q.

2. Unit, symbol: J/kg, (J/m3) (analogy: unit of speed or density)

4. Calculation formula:

1. Formula: Q=mq (i.e. mass multiplied by calorific value)

2. Example: Q=mq

When Xiao Ming used a stove to boil water, he consumed a total of 1.5kg of bituminous coal. How much heat is released when the bituminous coal is completely burned (the calorific value of bituminous coal q=2.7×107J/kg)?

Solution: Q=mq=1.5kg×2.7×107J/kg =4.05×107J

Answer: The heat released by complete combustion of these coals is 4.05×107J

5. Fuel utilization rate:

think:

In the above example, Xiaoming used 1.5kg of bituminous coal to boil water. The heat released by complete combustion of these coals is 4.05×107J. Is the actual heat released 4.05×107J? Why? What about the actual amount of heat absorbed by the water?

The heat actually absorbed by water is called effectively utilized heat.

Energy losses in heat engines:

The heat taken away by the exhaust gas;

Heat is lost after the cylinder components absorb heat;

The energy consumed in overcoming friction to do work;

Incomplete combustion of fuel;

All are causes of energy loss. Therefore, improving the efficiency of heat engines can improve fuel utilization.

Keywords: Utilization of internal energy teaching courseware, heat engine teaching courseware, New People's Education Edition ninth grade physics PPT courseware, ninth grade physics slide courseware download, utilization of internal energy PPT courseware download, heat engine PPT courseware download, .ppt Format

For more information about the "Utilization of Internal Energy in Heat Engines" PPT courseware, please click on the Utilization of Internal Energy in Heat Engine ppt ppt tab.

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Update Time: 2024-11-22

This template belongs to Physics courseware People's Education Edition Ninth Grade Physics Complete Book industry PPT template

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