High Temperature Reservoir Low Temperature Reservoir Introduction How does it work? Refrigeration and air conditioning is used to cool products or a building environment. High Temperature Reservoir Low Temperature Reservoir R Work Input Heat Absorbed Heat Rejected Refrigeration & AC Refrigeration and air conditioning is used to cool products or a building environment. The refrigeration or air conditioning system (R) transfers heat from a cooler low-energy reservoir to a warmer high-energy reservoir

Principles of Refrigeration Based in Second law of thermodynamics. Heat doesn’t flow from a low temperature body to high temperature body with out the help of an external work. External work is done by 1. Compressor 2. Condenser etc

Refrigerant ) A refrigerant is a substance that carries heat from the  refrigerated space or body to the outside surrounding.  2) Therefore a refrigerant may be defined as any substance that  absorbs heat either by expansion or vapourisation and rejects it  through condensation.  3) In Mechanical refrigeration systems refrigerant is subjected to  cyclic thermodynamic processes, so that it is forced to vapourise in  the evaporator by absorbing heat from refrigerated space and it is  forced to condense and convert into liquid in the condenser by  rejecting heat to surrounding.  4) The blood of any Refrigerating system is the refrigerent  circulating inside the system. 

Desirable Properties of a Good Refrigerant  1) Thermodynamic Properties :-  a) Boiling Point :- It should have Low Boiling Point.  b) Freezing Point :- It should be below the Evaporator temperature.  c) Evaporative Pressure :- It should be above Atmospheric pressure.  d) Condensing Pressure :- It should have LOW Condensing pressure.  e) Latent Heat of Vapourisation :- It should have HIGH Latent heat of  Vaporisation.  f) Critical Temperature & Pressure :- It should be above the  condensing Temperature & Pressure. 

2) Chemical Properties :-  a) Toxicity :- It should not be Poisonous or injurious . It should not  be non-irritating to eyes.  b) Corrosiveness :- It should not be corrosive & should not have any  effect on materials used in equipment.  c) Leak Detection :- It should have less tendency to leak & if it is  leaking it should be easily detectable.  d) Flammability :- It should not be Inflammable.  e) Miscibility with Oil :- It should be immiscible with oil & should  not have any effect on the properties of Oil used for Lubrication.  f) Effect on Foodstuff :- It should not affect on food articles Or  make them poisonous or unportable. 

3) Physical Properties :-  a) Specific Volume :- It should be LOW in Vapour state.  b) Viscosity :- It should have LOW viscosity.  c) Thermal Conductivity :- It should have HIGH Thermal Conductivity.  d) Di-Electric Strength :- It should have High strength. 

Terminology Refrigerator- machine used to extract heat from body at low temperature to high temperature. Refrigerant- It is liquid capable of absorbing heat from the other substance. Capacity of Refrigerator- It is the rate at which heat can be removed from the cold body. Unit- ton of refrigeration One ton of refrigeration is defined as the quantity of heat required to freeze one ton of water at 0 C in 24 hours. Value is 3.5 kJ/sec. Coefficient of Performance- Ratio of heat absorbed to the workdone. COP- Heat absorbed/ Work done Refrigerant effect- Ratio between heat removed and the time taken. Heat removed/ time taken. Ton of Refrigeration- Quantity of heat absorbed to freeze one ton of water in duration at 24 hrs at 0  C. TOR= 210kJ/min

Introduction How does it work? Refrigeration & AC Thermal energy moves from left to right through five loops of heat transfer: 1) Indoor air loop 2) Chilled water loop 3) Refrigerant loop 4) Condenser water loop 5) Cooling water loop Refrigeration & AC There are several heat transfer loops in a refrigeration system as shown in Figure 2. Thermal energy moves from left to right as it is extracted from the space and expelled into the outdoors through five loops of heat transfer: Indoor air loop. In the left loop, indoor air is driven by the supply air fan through a cooling coil, where it transfers its heat to chilled water. The cool air then cools the building space. Chilled water loop. Driven by the chilled water pump, water returns from the cooling coil to the chiller’s evaporator to be re-cooled. Refrigerant loop. Using a phase-change refrigerant, the chiller’s compressor pumps heat from the chilled water to the condenser water. Condenser water loop. Water absorbs heat from the chiller’s condenser, and the condenser water pump sends it to the cooling tower. Cooling tower loop. The cooling tower’s fan drives air across an open flow of the hot condenser water, transferring the heat to the outdoors. (Bureau of Energy Efficiency, 2004)

Types of Refrigeration Ice refrigerator- Ice is kept in cabinet. Air refrigerator- Air is used as working medium Vapor refrigerator: Vapour Compression Refrigeration (VCR) Vapour Absorption Refrigeration (VAR) Working medium: Ammonia, Co2, So2, Freons Refrigeration & AC The two principle types of refrigeration plants found in industrial use are: Vapour compression refrigeration (VCR) and vapour absorption refrigeration (VAR). VCR uses mechanical energy as the driving force for refrigeration, while VAR uses thermal energy as the driving force for refrigeration.

Vapour Compression Refrigeration Type of Refrigeration Vapour Compression Refrigeration Refrigeration cycle Condenser Evaporator High Pressure Side Low Pressure Side Compressor Expansion Device 1 2 3 4 Refrigeration & AC The refrigeration cycle is shown in the Figure and can be broken down into the following stages:---

Vapour Compression Refrigeration Type of Refrigeration The superheated vapour enters the compressor where its pressure is raised. Vapour Compression Refrigeration Refrigeration cycle Condenser Evaporator High Pressure Side Low Pressure Side Compressor Expansion Device 1 2 3 4 Refrigeration & AC The refrigeration cycle is shown in the Figure and can be broken down into the following stages:--- 2 – 3. The superheated vapour enters the compressor where its pressure is raised. The temperature will also increase, because a proportion of the energy put into the compression process is transferred to the refrigerant.

Vapour Compression Refrigeration Type of Refrigeration The high pressure superheated gas is cooled in several stages in the condenser Vapour Compression Refrigeration Refrigeration cycle Condenser Evaporator High Pressure Side Low Pressure Side Compressor Expansion Device 1 2 3 4 Refrigeration & AC The refrigeration cycle is shown in the Figure and can be broken down into the following stages:--- 3 – 4. The high pressure superheated gas passes from the compressor into the condenser. The initial part of the cooling process (3-3a) de-superheats the gas before it is then turned back into liquid (3a-3b). The cooling for this process is usually achieved by using air or water. A further reduction in temperature happens in the pipe work and liquid receiver (3b - 4), so that the refrigerant liquid is sub-cooled as it enters the expansion device

Vapour Compression Refrigeration Type of Refrigeration Liquid passes through expansion device, which reduces its pressure and controls the flow into the evaporator Vapour Compression Refrigeration Refrigeration cycle Condenser Evaporator High Pressure Side Low Pressure Side Compressor Expansion Device 1 2 3 4 Refrigeration & AC The refrigeration cycle is shown in the Figure and can be broken down into the following stages:--- 1 – 2. Low-pressure liquid refrigerant in the evaporator absorbs heat from its surroundings, usually air, water or some other process liquid. During this process it changes its state from a liquid to a gas, and at the evaporator exit is slightly superheated. 2 – 3. The superheated vapour enters the compressor where its pressure is raised. The temperature will also increase, because a proportion of the energy put into the compression process is transferred to the refrigerant. 3 – 4. The high pressure superheated gas passes from the compressor into the condenser. The initial part of the cooling process (3-3a) de-superheats the gas before it is then turned back into liquid (3a-3b). The cooling for this process is usually achieved by using air or water. A further reduction in temperature happens in the pipe work and liquid receiver (3b - 4), so that the refrigerant liquid is sub-cooled as it enters the expansion device.CondenserEvaporatorHigh Pressure SideLow Pressure SideCompressorExpansion Device1234 4 - 1 The high-pressure sub-cooled liquid passes through the expansion device, which both reduces its pressure and controls the flow into the evaporator

Vapour Compression Refrigeration Type of Refrigeration Low pressure liquid refrigerant in evaporator absorbs heat and changes to a gas Vapour Compression Refrigeration Refrigeration cycle Condenser Evaporator High Pressure Side Low Pressure Side Compressor Expansion Device 1 2 3 4 /Refrigeration & AC The refrigeration cycle is shown in the Figure and can be broken down into the following stages:--- 1 – 2. Low-pressure liquid refrigerant in the evaporator absorbs heat from its surroundings, usually air, water or some other process liquid. During this process it changes its state from a liquid to a gas, and at the evaporator exit is slightly superheated.

Vapour Compression Refrigeration Type of Refrigeration Vapour Compression Refrigeration Type of refrigerant Refrigerant determined by the required cooling temperature Chlorinated fluorocarbons (CFCs) or freons: R-11, R-12, R-21, R-22 and R-502 Refrigeration & AC A variety of refrigerants are used in vapor compression systems. The choice of fluid is determined largely by the cooling temperature required. Commonly used refrigerants are in the family of chlorinated fluorocarbons, CFCs, also known as freons: R-11, R-12, R-21, R-22 and R-502.

Vapour Compression Refrigeration Type of Refrigeration Vapour Compression Refrigeration Choice of compressor, design of condenser, evaporator determined by Refrigerant Required cooling Load Ease of maintenance Physical space requirements Availability of utilities (water, power) Refrigeration & AC The choice of refrigerant and the required cooling temperature and load determine the choice of compressor, as well as the design of the condenser, evaporator, and other auxiliaries. Additional factors such as ease of maintenance, physical space requirements and availability of utilities for auxiliaries (water, power, etc.) also influence component selection.

Types Of Air Conditioner Air Conditioning System An air conditioning system is an assembly of different part of the system used produce a specified condition of air within a require space or building. The basic elements of air conditioning system:-- Fans : For circulation of air Filters : For cleaning air Heating Elements : Heating of air(It may be electric heater , steam , hot water. Control System : It regulates automatically the amount of cooling or heating. Grill : It adjust the direction of the conditioned air to the room. Tray : It collects condensed water. Refrigerating Plant : provide cooling . It consist of compressor/generator and absorber,eveporator,condensor,expansion device(capallary tube). Refrigeration & AC Depending on applications, there are several options / combinations of air conditioning, which are available for use: Air conditioning (for space or machines) Split air conditioners Window Air Conditioner

Window Air Conditioner Split Air Conditioners Types Of Air Conditioner Window Air Conditioner Split Air Conditioners Refrigeration & AC Depending on applications, there are several options / combinations of air conditioning, which are available for use: Air conditioning (for space or machines) Split air conditioners Window Air Conditioner

Window Air Conditioner Types Of Air Conditioner Window Air Conditioner Refrigeration & AC Depending on applications, there are several options / combinations of air conditioning, which are available for use: Air conditioning (for space or machines) Split air conditioners Window Air Conditioner

Window Air Conditioner Types Of Air Conditioner Window Air Conditioner Working:--The air circulation system of the window air conditioner comprises of the following parts (please refer fig 4 & 5). 1) Blower: This is the small blower that is fitted behind the evaporator or cooling coil inside the assembly of the window air conditioner system. The blower sucks the air from the room which first passes over the air filter and gets filtered. The air then passes over the cooling coil and gets chilled. The blower then blows this filtered and chilled air, which passes through the supply air compartment inside the window air conditioner assembly. This air is then delivered into the room from the supply air grill of the front panel. 2) Propeller fan or the condenser fan: The condenser fan is the forced draft type of propeller fan that sucks the atmospheric air and blows it over the condenser. The hot refrigerant inside the condenser gives up the heat to the atmospheric air and its temperature reduces. 3) Fan motor: The motor inside the window air conditioner assembly is located between the condenser and the evaporator coil. It has double shaft on one side of which the blower is fitted and on the other side the condenser fan is fitted. This makes the whole assembly of the blower, the condenser fan and the motor highly compact. Refrigeration & AC Depending on applications, there are several options / combinations of air conditioning, which are available for use: Air conditioning (for space or machines) Split air conditioners Window Air Conditioner

Centralized air conditioning system