"Heat Engine" Heat and Energy PPT Courseware 3

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"Heat Engine" Heat and Energy PPT Courseware 3

Knowledge Review: Fill a test tube with some water as shown in the picture and seal it with a cork. When the test tube is heated to make the water boil, what phenomenon will be seen and what problem will it indicate?

The chemical energy of the fuel is converted into internal energy through combustion, and the internal energy of water vapor is converted into mechanical energy of the plug, which performs work on the plug.

Two ways to utilize internal energy

1. Use internal energy to heat objects

2. Use internal energy to do work

Classification of internal combustion engines

Internal combustion engines are divided into two categories: gasoline engines and diesel engines

Those that use gasoline as fuel are called gasoline engines.

A diesel engine that uses diesel as fuel is called a diesel engine.

1. Heat engine

1. Heat engine - a machine that uses internal energy to do work

When the fuel burns, the chemical energy is converted into internal energy and transferred to water and water vapor; the water vapor rushes out the plug, and the internal energy is converted into kinetic energy of the plug.

2. Types of heat engines

There are many machines that use internal energy to perform work, such as steam engines, internal combustion engines, steam turbines, jet engines, etc.

2. Gasoline engine

1. structure

2. work process

Working process of gasoline engine

stroke definition

Inhalation stroke: Inhaling a mixture of air and gasoline

Compression stroke: conversion of mechanical energy into internal energy

Power stroke: Internal energy is converted into mechanical energy, when the internal energy is maximum

Exhaust stroke: Exhaust exhaust gas

Want to discuss

1. Among the four strokes, which strokes undergo energy conversion?

2. Which stroke gives the car power?

3. Which stroke removes the car's exhaust?

4. When an old-fashioned motorcycle starts, it is necessary to step on the starting lever. Why is this?

5. What is the function of the "motor" in modern cars?

Advantages and Disadvantages of Gasoline and Diesel Engines

The gasoline engine has high speed, simple structure, light weight, low cost, stable operation, and easy use and maintenance. Gasoline engines are widely used in cars, especially small cars, and they still remain in use today.

Diesel engines are relatively bulky and are mainly used on trucks, tractors, trains and ships.

The thermal efficiency of diesel engines is 30% higher than that of gasoline engines. Therefore, from the perspective of saving energy and reducing fuel costs, the promotion and use of diesel engine cars is of great significance.

Among the four strokes of a gasoline engine, only the ________ gas does work externally. The other three strokes are auxiliary strokes, which are completed by the ________ installed on the crankshaft. It must be started by external force.

Summary: A working cycle of a gasoline engine includes ____ strokes, piston reciprocating ____ times, crankshaft rotation ____ times, and work done ____ times. There are ____ energy transformations.

practice

1. Please tell us the main differences in the structure and working process of gasoline engines and diesel engines.

2. During the compression stroke of an internal combustion engine, _______ energy is converted into _______; during the power stroke, _______ energy is converted into _______ energy.

3. The stroke completed by flywheel inertia is ( )

4. The working material of the gasoline engine is compressed during the compression stroke, and the ( ) in the cylinder

A． Pressure increases, temperature decreases

B． pressure decreases, temperature increases

C. Pressure increases, temperature rises

D. pressure decreases, temperature decreases

5. Comparing gasoline engines and diesel engines, which of the following statements is correct ( )

A． The diesel engine inhales a mixture of diesel and air into the cylinder, while the gasoline engine inhales air.

B． They compress to the same degree during the compression stroke

C. The pressure of the gas that pushes the piston to do work in a diesel engine is higher than that in a gasoline engine

D. At the end of the compression stroke, the temperature in the cylinder of a gasoline engine is higher than that of a diesel engine

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For more information about the PPT courseware "Heat and Energy Thermal Engine", please click the Heat and Energy ppt Heat Engine ppt tab.

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Update Time: 2024-11-22

This template belongs to Physics courseware Lu Jiao Edition Ninth Grade Physics Volume 2 industry PPT template

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