• ac technician hvac diplomas #SudiCouncil #SEC #SaudiEmbassyAttestedDiploma #DiplomaForIqama #UAE
  • ac technician hvac diplomas #SudiCouncil #SEC #SaudiEmbassyAttestedDiploma #DiplomaForIqama #UAE

ID : 28430

ac technician hvac diplomas #SudiCouncil #SEC #SaudiEmbassyAttestedDiploma #DiplomaForIqama #UAE

Kotli Sattian, Pakistan

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ac technician hvac diplomas #SudiCouncil #SEC 

#SaudiEmbassyAttestedDiploma #DiplomaForIqama #UAEEmbassy 

#QatarEbassy #OmanEmbassy

CHAPTER # 1 

INTRODUCTION TO REFRIGERATION AND AIR CONDITION

Refrigeration

Refrigeration may be defined as the process of reducing and maintaining 

a temperature of a space or material below that of the surroundings. This 

is accomplished by removing heat from body being refrigerated and 

transferred it to another body whose temperature is higher than that of the 

refrigerated body or space. It is evident that refrigerating and heating are 

actually opposite ends of the same process. Often, it is the desired result 

that distinguishes one from the other. Refrigeration is basic to the heating, 

ventilation and air conditioning industry. One of the most important 

applications of refrigeration has been the preservation of perishable food 

products, food processing, packaging, storing and transportation by 

storing them at low temperatures. The effect of storage temperature on 

useful storage life of food products is given in Table 1. Refrigeration 

systems are also used extensively for providing thermal comfort to human 

beings by means of air conditioning. Air Conditioning refers to the 

treatment of air so as to simultaneously control its temperature, moisture 

content, cleanliness, odour and circulation, as required by occupants, a 

process, or products in the space. The subject of refrigeration and air 

conditioning has evolved out of human need for food and comfort. The 

purpose of refrigerator is to transfer heat from a cold chamber which is at 

a lower temperature than that of its surrounding. Elementary refrigerators 

have been used which utilizes the melting of ice or the sublimation of 

carbon-dioxide at atmospheric pressure to provide cooling effect

INTRODUCTION TO HVAC SYSTEMS

The goal of the heating, ventilating, and air conditioning (HVAC) system 

is to create and maintain a comfortable environment within a building.

The purpose of this period is to provide a method for understanding the 

components of different types of HVAC systems. The premise of this 

method is that any HVAC system can be dissected into basic subsystems. 

These subsystems will be referred to as “LOOPS.”  There are five primary 

loops that can describe virtually any type of HVAC system. „

1.Airside loop (yellow) „ 

2.Chilled-water loop (blue)

3.Refrigeration loop (green)

4.Heat-rejection loop (red) 

5.Controls loop (purple) 

First (virtually any HVAC system)

 Second (temperatures) 

Third (humidifying the space, Focused on comfort cooling, not heating)

In order to determine how much supply air is needed for a given space, 

and how cold and dry it must be, it is necessary to determine the rate at 

which sensible heat and moisture (latent heat) enter, or are generated 

within, the conditioned space. 

Figure 6 shows typical sources of heat and moisture, which are 

commonly called cooling loads: „ 

•Conduction heat gain from outdoors through the roof, exterior 

walls, and glass windows or skylights. „ 

•Solar radiation heat gain through glass windows or skylights. „ 

•Conduction heat gain through the ceiling, interior partition 

walls, and the floor. „ 

•Internal heat and moisture generated by people, lights, 

appliances, and equipment in the space. 

•Heat gain from air infiltrating into the space from outdoors.

The next component of the airside loop is a supply fan that delivers the 

SUPPLY AIR (SA) to the space. In the example in Figure 7, air is supplied 

to the conditioned space to maintain a desired temperature of 75ºF 

(23.9ºC) in the space. This same supply fan is often used to also draw the 

return air out of the space. Alternatively, some systems use a second fan, 

called a return fan, to draw air from the space and move it back to the 

equipment that contains the supply fan. 

Another one of the comfort requirements is to provide an adequate 

amount of fresh, outdoor air to the space. In this example, the required 

amount of OUTDOOR AIR (OA) for ventilation is brought into the building 

and mixed with the recirculated portion of the RETURN AIR (RA). The 

remaining return air, that which has been replaced by outdoor air, is 

exhausted as EXHAUST AIR (EA) from the building.

However, the air must also be filtered. In a typical HVAC system, the 

MIXED AIR (MA) passes through a filter to remove many of the airborne 

contaminants.

CHAPTER # 2

The main job of the evaporator coil is to cool the refrigerant so that it can 

absorb the heat. As the fan blows air over the coil, the refrigerant 

becomes cold and turns into a vaporous state

The function of a cooling coil is to reduce the temperature of the fluid 

passing through or over it. Cooling coil is a part of a heat exchanger. It 

either carries the cooling fluid around it whereby the fluid inside the coil is 

cooled or inside it whereby the fluid outside is cooled. 

When cooling coils are used for temperature control in bioreactors, there 

is an interaction between heat transfer processes and the hydrodynamic 

conditions

HEAD OFFICE:  2nd Floor, Yasir Plaza, Qadeer Road Khanna Pul, 

RawalpindiContact Office: +92303-5530865, 0321-9606785, 0331-

5145601, 0349-5021336

Email: ipatsedu@gmail.com    Website: www.ipatsedu.com 

 

 

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