Module 1 Refrigeration and Air- Conditioning PDF

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TLE 106:TEACHING COMMON COMPETENCIESIN INDUSTRIAL ARTSModule 1REFRIGERATION AND AIRCONDITIONINGName: ______________________________________ Year and Section: ___________________Instructor: RANIEL P. NATIVIDAD Remarks:At the end of the lesson students shall be able to;A. Identify the basic tools and ...

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REFRIGERATION AND AIR CONDITIONING TLE 106: TEACHING COMMON COMPETENCIES IN INDUSTRIAL ARTS Module 1

Name: ______________________________________ Year and Section: ___________________ Instructor: RANIEL P. NATIVIDAD

Remarks:

LESSON

1

TOOLS AND EQUIPMENT

At the end of the lesson students shall be able to; A. B. C.

Identify the basic tools and equipment; define the difference between refrigeration and air conditioning; explain the relevance of using the proper tools and equipment in doing specific job requirement;

MOTIVATION: Guide Questions: - What do you think is the difference between Air- conditioner to an electric fan? - Which is better to use? Cite an example. - What is the difference between Refrigeration and Air- Conditioning?

Modern refrigerators and air-conditioners cannot operate without electricity. Some are even utilizing digital electronics particularly in their operation controls. The common home refrigerator and air-conditioning unit use hermetic motors (sealed electric motor and mechanical pump) that compress the refrigerant during its normal operation. REFRIGERATION – is the process of cooling by removing heat in an enclosed space and maintaining the temperature lower than ambient temperature. AIR-CONDITIONING – is one process of refrigeration. Aside from cooling and maintaining a low temperature in an enclosed space, it also involves conditioning of the air such as; humidity, air motion, cleaning, filtering, and even sanitizing the air. Refrigeration and air-conditioning tools are used in performing preventive maintenance and repair on air conditioners, refrigerators, freezers, and automotive air conditioner.

COMMON TOOLS AND EQUIPMENT:

Wrenches – are used to loosen bolts and nuts. They are open-end, box-end, adjustable, socket, and Allen wrench.

Screw drivers – are used to drive and loosen screws. They are classified as flat head, Philip’s head, and socket head screw drivers.

Cold Chisels – are used for cutting metals in jobs such as breaking rivets and splitting nuts.

Pliers – are tools used for holding objects by the grip of hand. They are classified as mechanical pliers, long nose pliers, slide side cutting pliers, and vise grip.

Tube cutters – are tools used to cut tubings made of copper, aluminum or steel. As the tool is turned, a sharp wheel cuts into tubing. Pressure is gradually increased until the tube is cut-off clearly and squarely.

Tube flaring tools – are tools used to flare the end of the tube to hold the flare nut.

Tube bending tools: a special kind of tool used to bend copper tubing in order not to bring the angle or side of the tube.

Tube swaging tools – are tools used to expand the end of the tubes of the same diameter for the purpose of making joints by soldering or brazing.

Blow torch – a gasoline torch used for heating solder in soldering or brazing process to join two tubes together.

Oxy-acetylene welder – equipment used in welding, cutting, and brazing. It is able to produce a very high intensity of heat from a combination of oxygen gas and acetylene fuel.

Service tank – is a Freon tank intended for servicing and recharging refrigerators and air-conditioning units. It has a limited capacity.

Service hose – a flexible hose attached to the service tank and gauges during the charging process.

Compound gauge – a special kind of gauge intended to measure the pressure and the amount of refrigerant (Freon) inside the system.

Multi-tester – an instrument used to measure voltage, resistance and dc currents.

Clamp meter – and instrument used to measure ac current. Usually used in diagnosing and monitoring the current of refs and air-con during troubleshooting operation.

Leak detector – an instrument used to detect areas or parts in the tube system where refrigerant is leaking.

Assessment: 1. What is Cooling and dehumidification? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 2. What is Heating and humidification? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 3. Compare and Contrast Refrigeration and Air- conditioning using Venn Diagram.

4. What is the relevance of using the proper tools and equipment in doing specific job requirement? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

LESSON

2

LAWS IN REFRIGERATION

At the end of the lesson students shall be able to; A.

identify and explain the major and other mechanical parts of a refrigeration system; describe the cooling system and its working principles; explain the different laws of refrigeration; illustrate the laws of refrigeration.

B. C. D.

MOTIVATION: Guide Questions: - What are the Laws in refrigeration? and how does it works? - How does the heat temperature convert into cold temperature? - How does each parts of the refrigeration and air- conditioning works? One has to know the three basic laws in refrigeration in order to understand theoretically how a refrigerator and air-conditioning unite operate. These laws revolve around the utility of heat energy to produce and maintain cooling. FIRST LAW - Heat flows from high to low temperature. - Heat travel through CONDUCTION from higher to lower temperature. Example: Loss of heat from the condenser to the environment. SECOND LAW -

Heat when applied to a liquid will convert it to vapor or gas. All liquid exposed to heat changes its state from liquid to vapor or gas when they attain their respective boiling point. This process is called EVAPORATION.

Example: The transformation of liquid refrigerant to vapor from the evaporator coil to the suction line of the system. THIRD LAW -

Heat when eliminated from vapor or gas turns back to liquid.

-

The external temperature that is relatively colder takes the heat from the vapor (through conduction), this is known as CONDENSATION. Example: The transformation of hot refrigerant vapor from the condenser into a liquid refrigerant.

Three Major concept involved in refrigeration and air-conditioning: 1. Heat – is a form of energy. As the temperature of a substance increases, atoms moves rapidly, while the temperature decreases they slow down. 2. Temperature – is the degree of hotness and coldness of a substance it measures the heat intensity or heat level of a substance. 3. Pressure – it is the force per unit area. Four Major Mechanical Parts of a Refrigeration System

1. Compressor – (motor compressor) – considered as the heart of the system. It compresses the refrigerant into a superheated gas and pumps it to circulate in the entire tube system. This is where the COMPRESSION stage occurs. It is both a hermetic (totally sealed) and a reciprocating (dual action – suction and discharge) machine.

2. Condenser – cools down the superheated gas through conduction. This is where the gaseous refrigerant is turned to a liquid state that is known as the CONDENSATION stage. The cooling medium of a condenser can be water, brine or another refrigerant. The total amount of heat ejected in the condenser by the refrigerant is equal to the sum of the heat absorbed in the evaporator plus the heat of compression.

Expansion Valve/ Throttling device

3. Refrigeration flow control (expansion valve, capillary tube, or throttling device) – the part that reduced the high pressure of the hot liquid refrigerant and at the same time reduces its temperature before it enters the evaporator. This is a process known as the EXPANSION stage.

Capillary tube

4. Evaporator – this is where the refrigeration takes place. The cooled refrigerant absorbs latent heat and is transformed from liquid to vapor or gas before it returns to the compressor that is known as the EVAPORATION stage.

Other Accessories of the Mechanical Parts 1. The filter / Strainer – it cleans the refrigerant of any dirt or impurity it collects while circulating around the system. It is connected between the liquid line and the capillary tube.

2. The heat exchanger – it is a part where the capillary tube and suction tube are soldered together to exchange the low and high temperature that compensates one another.

3. The accumulator – it entraps the remaining liquid refrigerant that may have escaped from the evaporation. This is connected between the evaporator and the suction line.

The Three Passive Mechanical Parts

1. The Suction Line – found at the low side of the motor where the vapor from the evaporator passes on its way to the compressor motor. 2. Discharge line – passage way at the high side that drives vapor to condenser for superheating. 3. Liquid line – allows the high pressure liquid passage on its way to the strainer. The Cooling System and its Working Principles The refrigerant or air-conditioning unit is cooled by means of a cooling agent known as refrigerant. This substance is sealed inside the series of tubes of various sizes and is flowing in one direction in a cycle. This is known as the refrigeration cycle.

Assessment: 1. How a refrigerator works? _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ 2. How does the Four Major Mechanical Parts of a Refrigeration System works? _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ 3. State the three laws in refrigeration and explain each law. _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ 4. Based on your understanding illustrate the 3 laws of refrigeration.

5. Research 1 invention related to Refrigeration and Air- conditioning.

LESSON

THE REFRIGERATION CYCLE

3

At the end of the lesson students shall be able to; A. B. C. D.

describe the basic service operations; explain the refrigeration cycle; state the importance of the refrigeration cycle; illustrate the refrigeration cycle.

MOTIVATION: Guide Questions: - What are the 4 main components of the refrigeration? - How each components works? - What is a refrigerant? The refrigeration cycle starts and ends with the compressor. The refrigerant flows into the compressor where it is compressed and pressurised. At this point, the refrigerant is a hot gas. The refrigerant is then pushed to the condenser which turns the vapour into liquid and absorbs some of the heat. The refrigerant then proceeds to the expansion valve where it expands, losing pressure and heat. The refrigerant coming out of the expansion valve is cold and slow due to the loss of pressure. It enters the evaporator in a liquid state where the exchange of heat takes place thus cooling the load inside the refrigerator. As the gas cools down the load, it absorbs the heat which turns it into a gas. The gas is then pushed back into the compressor where it can start the cycle again.

Compressor Reduces volume & creates high pressure gas causing the temperature to rise.

Hot Gas

Hot liquid

Gas Evaporator Cold refrigerant chills equipment as it vaporizes; turning back into a gas it draws heat away from the refrigerator’s contents before exiting the evaporator.

Condenser Hot gas is cooled by air or water before being condensed to become a hot liquid.

Cold Refrigerant

Expansion Valve Hot liquid cools due to pressure decrease resulting in cold refrigerant.

Refrigerant – is cooling substance in a refrigerator or air-conditioning unit. It is heat carrying medium that absorbs heat at low temperature. Properties of Refrigerant: 1. 2. 3. 4. 5. 6. 7. 8.

Low boiling point. Safe and non-toxic. Ease of liquefy action at moderate pressure and temperature. High latent heat value. Ability to operate on positive pressure. No effect on moisture. Mix well with oil. Non-corrosive to metal. Overview: The refrigeration cycle basically involves the movement of refrigerant from one place to the next and in different forms with the ultimate goal of pulling down temperatures whether in a cabinet, counter or even cold room format. The one main importance of learning how your commercial fridge works is so that you understand how to clean and maintain equipment effectively. For example, understanding that your fridge uses an air-cooled condenser will help you find the ideal position for your unit in order to make its work easier and lower the energy consumption. By understanding the basics, only then can one fully benefit from their commercial refrigeration.

Common Refrigerants used in household red and air-con units R-12 – Dichlorodifluoromethane (CCL2F2) – this is commonly used in refrigerators and automotive air-con units. R-22 – Monochlorodifluoromethane (CGCLF2) – this is commonly used in domestic airconditioning units. R-134a – Tetrafluoroethane (HFC 134a) – refrigerant used to substitute R-12 and R 22 which are known to be environment friendly. BASIC SERVICE OPERATIONS 1. Diagnosing – determining the status of the system. If the system is still operating, checking of current by means of an ammeter is the first step to be done. 2. Leak Testing – this is the process of determining a break or a hole in the sealed tube where the refrigerant escapes causing abnormally in the refrigeration cycle.

3. Vacuuming – this is the process of removing air gas in an enclosed space.  Self-vacuuming – a process of removing air, gas, moisture, dirt, and other foreign materials in the refrigeration system using its own motor compressor to pump them out.  Using a vacuum pump – this method of vacuuming uses a vacuum pump instead of the motor compressor of the refrigerator unit. This is said to be more effective and more efficient way of vacuuming as compared to selfvacuuming. Vacuuming must always be performed before charging or recharging the system with refrigerant. CHARGING THE SYSTEM – this is the process of filling or refilling the system with a cooling agent known as refrigerant to an amount equivalent to the full load rating of the system, An overcharged system may cause the motor compressor to be burned or damaged and an undercharged system will operate abnormally.

Assessment: Make your own creative graphic organizer on refrigeration cycle.

Rubrics in graphic organizer: Criteria

4

3

2

1

Organization

Extremely well organized. Order & structure of information is compelling and flows smoothly.

Organized. Structure allows reader to move through content without confusion.

Poorly organized. A clear sense of direction is not evident. Flow is frequently interrupted.

Content

Thorough and insightful understanding of content. Enthusiastically uses materials and ideas for enhancement. Insightful and well considered ideas making multiple connections.

Complete understanding of content.

Somewhat organized structure allows reader to move through some of the content without confusion. Flow is sometimes interrupted. Show some understanding of content.

Use of materials and ideas for enhancement.

Shows some use of materials and ideas.

Ideas are considered; more than one thoughtful connection is made.

Ideas are somewhat on topic; makes some connections

Shows minimal effort for enhancement of material and ideas. Ideas are unclear few connections.

Creativity

Idea

Show incomplete understanding of material.

Analysis: 1. What is the importance of the refrigeration cycle? _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ 2. In your own words, explain the refrigeration cycle. _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ 3. How refrigerant works? _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ _____________________________________________________________________________________________ 4. Explain this picture.

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