Vapor-compression cyclic refrigerators

By / Aly Dawod

Introduction

• In this case study we will discuss the design and manufacture processes of refrigerators , specially Vapor-compression cyclic refrigerators

Introduction

• We all know about the essential use of refrigerators to the consumer as well to the commerce.

• Consumer use it at homes to preserve their food fresh.

• Its commerce use is represented in keep the harvest fresh till it arrives to the factory or to the market

Introduction

• Our example for this case study is the ordinary refrigerator that you can find it at most of our homes.

• Knowing that its system ( Vapor-compression cycle ) can be applied on bigger scales and for other uses as mentioned.

The manufacture process

• The first stage of manufacturing is cutting and forming the sheets.

• Cutting the sheets must be according to the specified dimensions for the outer body of the refrigerator.

• The top and the doors of the refrigerators must be smaller than the sides and the rear.

The manufacture process

• The next process is to bend and drill the sheets and connecting the sheets together by Hemming then washing the sheets and painting it.

Rolling

Bending

The manufacture process

• Then it pass Through a Desalination unit to get rid of salts and fixing the painting.

• Then the drying process.

Painting

The manufacture process

• Painting is done by electrostatic method at 70 KV.

The manufacture process

• The second stage is manufacturing of the internal part of the refrigerator.

• It is made using die press operation.• 5m.m Plastic sheet.• The process is accompanied with heat energy that help

the forming to take place faster.

The manufacture process

• Next Stage is assembling the sheets with the internal body and fix them by hemming.

• Then we rivet them.

Riveting process

The manufacture process

• The next stage is to manufacturing the freezer • It is made by an aluminum sheet Which is bent on

machine which bend the sheet as a four faces cube.

• Then the back is assembled by a compressor.

• Then a frame is assembled and riveted.

The manufacture process

• The next stage is to attach the evaporators, one for the upper part and one for the lower part of the refrigerator.

• The we adhere the evaporator to the body firmly by PVC

adhesive material to not release heat.

Evaporator

The manufacture process

• The next stage is to avoid condensation by attaching condenser which convert the gas to liquid.

The manufacture process

• After that we attach the Thermal expansion valve (throttle valve) which is control the amount of refrigerant (Freon)

The manufacture process

• The rear of the Cabinet (the bottom) is as shown :-

The manufacture process

• The last stage is to attach a thermostat which must be very attached to the body to sense the heat.

• Its function is to break down the circuit if the temperature increase.

• And to turn it on if the temperature decreases.

thermostats

Ergonomics

• The top freezer refrigerator was never an ergonomic success.

• It puts the most used part of the refrigerator down by the floor where a lot of stooping and bending is required to use it.

• Bottom freezer units are better, The main part of the refrigerator is placed between waist and shoulder. (French door refrigerator)

Ergonomics

• But the cost of top freezer refrigerators is less than the bottom freezer ones.

French door refrigerators

Product life cycle

• According to appliance Magazine's report in 2011 the Average Life Span of refrigerators is between 10 and 16 years.

• The Virtual Repairman website's calculations are between 8 and 14 years.

Product life cycle

• There are three main stages for recycling refrigerators :- 1) Chemical recycling by getting the coolant out of the system. 2) Saw into three pieces to separate the metal, foam, and plastic lining. 3) Metal, glass, and plastic recycling.

Testing and rating

• All the parts must be tested before assembling it. (the compressor, the condenser fan, the thermostat …etc.)

• The cooling system and the refrigerant also must be tested.

• The system must prevent over frosting.

Frost

Testing and rating

• The rating of refrigerators is based on many points like :-

- Capacity - Storage and features. - Water and ice Dispenser. - Warranty and energy usage. - Help and support.