HVAC: The Refrigeration Cycle

 

Lesson Overview

Media: Video (19 minutes)

Seat Time: 4 Classes | 200 minutes teaching

 

Goal:

To summarize the components and processes involved in the refrigeration cycle

 

Description:

This lesson defines the terms and principles associated with the refrigeration cycle, including the laws of thermodynamics and states of matter. The lesson also identifies the four major components of a refrigeration system and then explains the refrigerant chemicals and unique properties which allows refrigeration systems to function. Finally, the lesson ends with a comprehensive walkthrough of the refrigeration cycle.

 

Objectives:

1.    To define the basic terminology associated with the refrigeration cycle.

2.    To identify the four primary components of the refrigeration cycle.

3.    To explore various types of refrigerants.

4.    To summarize the effect each of the four primary components has on refrigerant during the refrigeration cycle.

 

Class 1

Class Overview:

Introduction Video Segment

Action Plan

Vocabulary Handout

Key Concepts

Introduction Check for Understanding

Vocabulary Flashcard Activity

 

Essential Questions:

1.    What is the basic terminology associated with the refrigeration cycle?

 

Step 1: Bell Ringer:

·         On the board, draw water vapor, a glass of water and ice. As each student comes in, ask them to add a fact about the various states of matter and how materials change states to the drawing. Facts could include names for transitions between states and conditions needed for state changes.

Step 2: Distribute the Action Plan, Vocabulary Handout and Key Concepts.

·         The Action Plan lays out a list of tasks for students to complete during the lesson.

·         The Vocabulary Handout is a list of terms used throughout the lesson.

·         The Key Concepts is an outline which identifies the main ideas presented in the lesson which students can fill in to aid in note taking during the lesson.

Step 3: Show the Introduction video segment.

·         This video is seven minutes long.

·         Be sure to utilize the Key Concepts for this segment of the lesson.

Step 4: Administer the Introduction Check for Understanding.

·         The check for understanding is a short review of the content presented in the lesson.

Step 5: Students should complete the Vocabulary Flashcards Activity.

·         Students will need to be able to cut out the flashcards as part of the activity.

Step 6: Exit Ticket:

·         Have students revisit the board, ask if there is anything they would like to add or adjust after viewing this segment of the lesson.

 

Class 2

Class Overview:

Refrigeration Cycle Components Video Segment

Refrigerants Video Segment

Action Plan

Refrigeration Cycle Components Check for Understanding

Refrigerants Check for Understanding

Label the Components Activity

Vocabulary Game Activity

 

Essential Questions:

1.    What are the four primary components of the refrigeration cycle?

2.    What are the various types of refrigerants?

 

Step 1: Bell Ringer:

·         Have students write down what they know about refrigeration cycles and communicate their experiences of observing air conditioning units and refrigerators or freezers.

Step 2: Show the Refrigeration Cycle Components video segment.

·         This video is three minutes long.

·         Be sure to utilize the Key Concepts for this segment of the lesson.

Step 3: Administer the Refrigeration Cycle Components Check for Understanding.

·         The check for understanding is a short review of the content presented in the lesson.

Step 4: Show the Refrigerants video segment.

·         This video is three minutes long.

·         Be sure to utilize the Key Concepts for this segment of the lesson.

Step 5: Administer the Refrigerants Check for Understanding.

·         The check for understanding is a short review of the content presented in the lesson.

Step 6: Have students complete the Label the Components Activity.

·         Students will label the essential refrigeration components.

Step 7: Students should complete the Vocabulary Game Activity.

·         Pass out vocabulary words from the Vocabulary Game Activity Instructor File.

Step 8: Exit Ticket:

·         Have students answer an Essential Question as they leave class.

 

Class 3

Class Overview:

The Refrigeration Cycle Video Segment

Action Plan

Refrigeration Cycle Student Handout

The Refrigeration Cycle Check for Understanding

Model the Refrigeration Cycle Project

 

Essential Questions:

1.    How do the primary components of a refrigeration or air conditioning system work together to complete the refrigeration cycle and create the cooling effect?

 

Step 1: Bell Ringer:

·         Pass out the Refrigeration Cycle Student Handout when students come into the classroom. Ask students to look over the handout and write down two questions they have about the cycle.

Step 2: Show The Refrigeration Cycle video segment.

·         This video is five minutes long.

·         Be sure to utilize the Key Concepts for this segment of the lesson.

Step 3: Administer The Refrigeration Cycle Check for Understanding.

·         The check for understanding is a short review of the content presented in the lesson.

Step 4: Have students begin the Model the Refrigeration Cycle Project.

·         Students should complete the schematic drawing portion of the project.

Step 5: Exit Ticket:

·         Have students answer the questions they asked at the beginning of class. If students still have unanswered questions have them turn them in to you as they leave.

 

Class 4

Class Overview:

Action Plan

HVAC: The Refrigeration Cycle Final Assessment

Model the Refrigeration Cycle Project

 

Step 1: Bell Ringer:

·         Have students review the for the assessment.

Step 2: Administer the HVAC: The Refrigeration Cycle Final Assessment.

·         The assessment is a comprehensive assessment covering material throughout the entire lesson.

Step 3: Have students complete the Model the Refrigeration Cycle Project.

·         Students should complete the second half of the project asking students to learn about and label a real refrigeration or HVAC system.

Step 4: Exit Ticket:

·         Have students write down three things they learned during this lesson and turn in.

 

Activity Overview

Vocabulary Flashcards

Students will be creating flashcards for the key vocabulary terms from the lesson. They will write the vocabulary definitions in their own words, allowing them to work through the meaning of definitions. Then students will test one another with their flashcards.

 

Accommodations:

Allow students to use their vocabulary handout to reference the list of terms and their definitions.

 

Modifications:

Provide students with pre-made flashcards to study.

 

Extension:  

Have students complete a four-corners vocabulary activity for each term, in which they list the term, the definition, draw a picture and use the word in a sentence.

 

 

Label the Components

Students will label the different components and metering device types used in the refrigeration cycle. This activity will help students study for the final exam and ensure they can identify components when searching for them in real refrigeration systems.

 

Accommodations:

Allow students to use their Key Concepts and Refrigeration Cycle Student Handout with descriptions of the components to help them complete the activity.

 

Modifications:

Have students only label the components and provide the answer key for students to use to study the types of metering devices.

 

Extension:  

Have students locate five photos of each different component and type of metering device online to show how each element differs in appearance from system to system.

 

 

Vocabulary Game

Students will be playing a vocabulary game to help them understand and apply the key terms from the lesson. You will need to print and cut out the vocabulary cards located in the Vocabulary Game Activity Instructor File.

 

Accommodations:

Allow students to use their vocabulary handout to reference the list of terms and their definitions.

 

Modifications:

Have students study a list of only five vocabulary terms, then pair with yourself or an aide and complete the activity with words from the shorter list so they can have support while working on learning the terms.

 

Extension:   

Have students make Taboo® cards for the vocabulary list. Each card has the word the player will be trying to make their team guess, but will also include five words important to the term’s definition or concept which cannot be used to describe the word. Challenge students to play the game.

 

Project Overview

Model the Refrigeration Cycle

Students will be drawing a schematic of the refrigeration cycle, labeling the components, refrigeration lines and state of refrigerant at each stage. You should briefly introduce schematic drawings and explain their purpose is to create simple representations of a circuit aimed at demonstrating how the circuit works. If this is your students’ first time with schematic drawings, you may need to spend time scaffolding schematics and the expectations for what one looks like. Once students have completed the schematic, they will move to identifying these features in a real refrigeration system. Allow your students to use a classroom air conditioning or refrigeration unit to identify and photograph the various components to create a document which labels and describes each feature. Ice machines and mini refrigerators are cheap options for model air conditioning units and it is typically easy to remove the back and examine all components without damaging the unit. If you are unable to provide a classroom unit, take students on a tour of the school’s HVAC system and have them identify the components and what is happening to the refrigerant or instruct students to safely inspect their home system. While school and home HVAC systems may not allow students to see all components, this can still be a valuable way for students to apply what they have learned about the system to real-life machines.

 

Accommodations:

Provide students with a base schematic already drawn to label.

 

Modifications:

Students should be asked to only label the four components of the refrigeration unit.

 

Extension:  

Have students draw the schematic of the real system they looked at in the second part of the project. Those types of systems tend to be more complex and will require students to complete some research on additional components and circuit organization in refrigeration units before completing the task.

 

Career & Technical Student Organizations

Skills USA

Heating, Ventilation, Air Conditioning & Refrigeration (HVACR)

 

 

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