MODULE 5

• The purpose of this module is to help you understand how heat engine works
• This module contains one lesson: Heat Engines
• After going through this module, you are expected to

  • Explain how heat transfer and energy transformation make heat engines work
  • Construct a model to demonstrate what heat can do at work
  • Analyze the four-stroke cycle of heat engine
  • Infer that heat transfer can be used to do work, and that work involves the release of heat
  • Explain why machines are never 100-percent efficient
• Heat engine


  An engine that extracts useful work by transferring heat from a cold reservoir to a hot one
• Four-stroke cycle of heat engine

  1. Intake

  2. Compression

  3. Power

  4. Exhaust
• The sum of the heat placed into the hot reservoir and the work collected equals the energy transferred from the cold reservoir
• Intake stroke


  The left side valve opens, the air-fuel mixture fills the cylinder
• Compression stroke


  The piston goes up and compresses the air-fuel mixture
• Power stroke


  The spark plug ignites the mixture, causing the temperature to rise
• Exhaust stroke


  The burned gases are forced out
• No engine is 100% efficient
• Thermal efficiency


  The amount of heat that is transformed into useful work
• Increasing the amount of energy added to the system by heat or decreasing the amount of energy given up by the system would increase the efficiency
• City of Good Character


  DISCIPLINE • GOOD TASTE • EXCELLENCE
• Apply the formula for efficiency

  1. Given and Unknown Data

  2. Solution (Formula and Solution)
• Heat engine's combusted gas

  Generates 295 J of energy and loses 140 J
• Thermal efficiency


  For exhausting heat in a single cycle
• Compute for the thermal efficiency of a truck

  Input energy of 454 J and 223 J exhaust heat
• Buses may also transport large numbers of people to remote areas


  1. Produces steam at 328 J and emits 113 J into the atmosphere

  2. What is the maximum possible value for the vehicle's thermal efficiency?
• Assume that the heat engine receives steam at 782 Kelvin and releases the excess portion at 31 degrees Celsius


  What would the heat engine's total efficiency be?
• Are the engines 100% efficient? If not, what happens to the remaining percent?
• If the system's waste energy is released, is there any effect on the environment? Briefly explain your answer.
• Heat engine


  Transforms the energy stored in fuel into force and motion
• Four stroke cycle of a heat engine

  • Intake
  • Compression
  • Power
  • Exhaust
• Determine the energy conversion that occurs in the turbine and turbine-powered generators


  1. The turbine is powered by high pressurized steam provided by the steam generator

  2. Turbine-powered generators generate electricity, which is then transferred to the transformer
• How does a powerplant generate electricity? Explain your answer.
• Construct a model to demonstrate that heat can do work

  1. You are a Model Designer

  2. Science teacher and Classmates

  3. As a model designer, construct your model on how to demonstrate how heat can do work using the following materials: candle, pencil, construction paper, thumbtacks, a piece of clay, matchsticks

  4. Create your model to show how heat can do work use your creativity and imagination and make a short video of yourself doing your model

  5. Creativity 10pts. Design is one-of-a-kind and reflects the topic's theme. The pattern and details are obvious.

  6. Content 10pts. It goes over the topic in detail and expresses the understanding of the subject clearly.

  7. Organization 10pts. The content is well-organized and demonstrates the originality of the work.