Air Conditioner Project 5o66k

Company Profile In c o rp or a t e d a nd p ro mo t e d i n 19 92 b y Mr Ka r t a r S i n gh, th e A mb e r Gr ou p i s a mo n g o t h e r t h i n gs , o ne o f t h e l a r ge s t o r i gi n a l e q u ip me n t ma n u f a c t u r e r o f w h i t e go od s i n In d i a . O ne f a c t o r th a t ha s l e d u s t h i s f a r i s ou r r e l e n t l e s s fo c u s on q ua l i t y. A t th e A mb e r Gr ou p w e fo l l o w s t r i c t qu a l i t y p ro c e s s e s a nd w e ar e a n IS O 90 01 - 20 08 c e r t i f i e d c o mp a n y. Un de r t h e a e gi s of th e A mb e r Gr ou p t h e r e a r e t wo d i s t i n c t en t i t i e s : A mb er En t e r p r i s e s In d i a P vt . Lt d . an d A mb e r A vi a t i o n Ind i a P vt . Lt d . A mb er In du s t r i e s i s a c on gl o me r a t e of 9 ma n uf a c t u r i n g un i t s t h a t a r e i n vo l ve d i n p ro du c i n g o r i gi n a l e qu i p me n t f or s o me o f t h e b i gge s t br a nd s i n In d i a wh i l e A mb e r A vi a t i o n i s en ga ge d i n aircraft

charters

a nd

training

of

pilots .

c o mme r c i a l

Some of top white good brands stake their reputations on our products every day and have done so for years. What makes giants like L.G, Videocon, Godrej, Whirpool, Blue Star, Philips and Voltas trust the insides of their products to us? It can be summed up in one word - trust. Our customers trust us. We manufacture and customize original equipment as per specifications and as

per

schedule.

Customer

service

is

not

a

word

we

use

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lightly.

Why are we one of the most cost-effective white good OEMs in India? •

We are based at strategic locations and well connected to the rest of the country.

•

Our in-house products, tool development facility and an active R&D department ensure quality and innovation thereby reducing costs.

•

Our backward integration across a wide range of components along with economies of scale keeps our costs low.

Partial Product List: 1. Split & Window Air Conditioners for commercial and residential use. 2. Package Air Conditioners for Indian Railways and commercial use. 3. Heat Exchangers. 4. Multi Flow Condensers. 5. Home appliances like Washing Machines, Refrigerators & Microwaves. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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6. Luminaries for commercial use. 7. Plastic Extrusion Sheets. 8. Vacuum Forming Components. 9. Injection Molding Components. 10.

Sheet Metal Components.

11.

Auto Parts.

Air-Conditioning Systems An air-conditioning or HVAC&R system consists of components and equipment arranged in sequential order to heat or cool, humidify or dehumidify, clean and purify, attenuate objectionable equipment noise, transport the conditioned outdoor air and recirculate air to the conditioned space, and control and maintain an indoor or enclosed environment at optimum energy use. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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The types of buildings which the air-conditioning system serves can be classified as: • Institutional buildings, such as hospitals and nursing homes • Commercial buildings, such as offices, stores, and shopping centers Air-Conditioning and Refrigeration 9-3 • Residential buildings, including single-family and multifamily low-rise buildings of three or fewer stories above grade • Manufacturing buildings, which manufacture and store products

Types of Air-Conditioning Systems In institutional, commercial, and residential buildings, air-conditioning systems are mainly for the occupants’ health and comfort. They are often called comfort air-conditioning systems. In manufacturing buildings, air-conditioning systems are provided for product processing, or for the health and comfort of workers as well as processing, and are called processing air-conditioning systems. Based on their size, construction, and operating characteristics, air-conditioning systems can be classified as the following. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Individual Room or Individual Systems An individual air-conditioning system normally employs either a single, self-contained, packaged room air conditioner (installed in a window or through a wall) or separate indoor and outdoor units to serve an individual room.

Space-Conditioning Systems or Space Systems. These systems have their air-conditioning cooling, heating, and filtration performed predominantly in or above the conditioned space.

Air Systems An air system is also called an air handling system or the air side of an air-conditioning or HVAC&R system. Its function is to condition the air, distribute it, and control the indoor environment according to requirements. The primary equipment in an air system is an AHU or air handler; both of these include fan, coils, filters, dampers, humidifiers (optional), supply and return ductwork, supply outlets and return inlets, and controls.

Water Systems

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These systems include chilled water, hot water, and condenser water systems. A water system consists of pumps, piping work, and accessories. The water system is sometimes called the water side of a central or space-conditioning system.

Main Components Compressor Compresses the refrigerant from low pressure (low temperature) to high pressure (high temperature). This conversion raises the boiling point to higher temperature levels, facilitating elimination of the heat brought by the outdoor air.

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Condenser This component receives gas at high pressure and high temperature from the compressor. In aircooled condensers, the metallic surfaces cool the gas which changes status and turns to liquid. In the case of water-cooled condensers, it is the circulation of the water that produces the same cooling effect.

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Evaporator When the refrigerant evaporates in the evaporator, it absorbs heat from the surrounding air and produces cooled air.

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Capillary Tube A narrowing of the tube connected along the line between the condenser and the evaporator with diameters ranging from 1 to 2 mm. and lengths ranging between 1 and 2 m, allows the adjustment of the amount of gas fed to the evaporator.

Electrical Parts Electric and electronic components needed by the various air conditioner functions. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Indoor Fan It exhausts air from the indoor environment and conveys it through the evaporator; the air is now cool and distributed back into the environment.

Outdoor Fan This causes the air to circulate through the condenser in order to cool the refrigerant.

Air-Conditioning Project Development and System Design -conditioning/HVAC&R system is to provide a healthy and comfortable indoor environment with acceptable indoor air quality, while being energy efficient and cost effective.

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ASHRAE Standard 62-1989 defines acceptable indoor air quality as “air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a sub-stantial majority (80% or more) of the people exposed do not express dissatisfaction.” In the building construction industry, air-conditioning or HVAC&R is one of the mechanical services; these also include plumbing, fire protection, and escalators. Air-conditioning design is a process of selecting the optimum system, subsystem, equipment, and components from various alternatives and preparing the drawings and specifications. Haines (1994) summarized this process in four phases: gather information, develop alternatives, evaluate alternatives, and sell the best solution. Design determines the basic operating characteristics of a system. After an air-conditioning system is designed and constructed, it is difficult and expensive to change its basic characteristics. The foundation of a successful project is teamwork and coordination between designer, contractor, and operator and between mechanical engineer, electrical engineer, facility operator, architect, and structural engineer. Field experience is helpful to the designer. Before beginning the design process it is advisable to visit similar projects that have operated for more than 2 years and talk with the operator to investigate actual performance.

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Engineer’s Responsibilities The normal procedure in a design-bid construction project and the mechanical engineer’s responsibilities are 1. Initiation of a project by owner or developer 2. Organizing a design team 3. Determining the design criteria and indoor environmental parameters 4. Calculation of cooling and heating loads. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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5. Selection of systems, subsystems, and their components. 6. Preparation of schematic layouts; sizing of piping and ductwork. 7. Preparation of contract documents: drawings and specifications. 8. Competitive biddings by various contractors; evaluation of bids; negotiations and modifications. 9. Advice on awarding of contract. 10. Monitoring, supervision, and inspection of installation; reviewing shop drawings. 11. Supervision of commissioning.

Moist Air Above the surface of the earth is a layer of air called the atmosphere, or atmospheric air. The lower atmosphere, or homosphere, is composed of moist air, that is, a mixture of dry air and water vapor. Psychrometrics is the science of studying the thermodynamic properties of moist air. It is widely used to illustrate and analyze the change in properties and the thermal characteristics of the airconditioning process and cycles. The composition of dry air varies slightly at different geographic locations and from time to time.

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The approximate composition of dry air by volume is nitrogen, 79.08%; oxygen, 20.95%; argon, 0.93%; carbon dioxide, 0.03%; other gases (e.g., neon, sulfur dioxide), 0.01%. The amount of water vapor contained in the moist air within the temperature range 0 to 100 F changes from 0.05 to 3% by mass. The variation of water vapor has a critical influence on the characteristics of moist air.

Air-Conditioning Processes An air-conditioning process describes the change in thermodynamic properties of moist air between the initial and final stages of conditioning as well as the corresponding energy and mass transfers between the moist air and a medium, such as water, refrigerant, absorbent or adsorbent, or moist air itself. The energy balance and conservation of mass are the two principles used for the analysis and the calculation of the thermodynamic properties of the moist air. Generally, for a single air-conditioning process, heat transfer or mass transfer is positive.

However,

for

calculations

that

involve

several

air-conditioning

processes, heat supplied to the moist air is taken as positive and heat rejected is negative.

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Air-Conditioning Cycle and Operating Modes An air-conditioning cycle comprises several air-conditioning processes that are connected in a sequential order. An air-conditioning cycle determines the operating performance of the air system in an air conditioning system. The working substance to condition air may be chilled or hot water, refrigerant, desiccant, etc. Based on the outdoor weather and indoor operating conditions, the operating modes of air-conditioning cycles can be classified as: • Summer mode: when outdoor and indoor operating parameters are in summer conditions. • Winter mode: when outdoor and indoor operating parameters are in winter conditions.

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• Air economizer mode: when all outdoor air or an amount of outdoor air that exceeds the minimum amount of outdoor air required for the occupants is taken into the AHU or PU for cooling. The air economizer mode saves energy use for refrigeration. Continuous modes operate 24 hr a day and 7 days a week. Examples are systems that serve hospital wards and refrigerated warehouses. An intermittently operated mode usually shuts down once or several times within a 24-hr operating cycle. Such systems serve offices, class rooms, retail stores, etc. The 24- hr dayand-night cycle of an intermittently operated system can again be divided into: 1. Cool-down or warm-up period. When the space is not occupied and the space air temperature is higher or lower than the predetermined value, the space air should be cooled down or warmed up before the space is occupied. 2. Conditioning period. The air-conditioning system is operated during the occupied period to maintain the required indoor environment. 3. Nighttime shut-down period. The air system or terminal is shut down or only partly operating to maintain a set-back temperature. Summer, winter, air economizer, and continuously operating modes consist of full-load (design load) and part-load operations. Part load occurs when the system load is less than the design load. The capacity of the equipment is selected to meet summer and winter system design loads as well as system loads in all operating modes. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Basic Air-Conditioning Cycle — Summer Mode A basic air-conditioning system is a packaged system of supply air at a constant volume flow rate, serving a single zone, equipped with only a single supply/return duct. A single zone is a conditioned space for which a single controller is used to maintain a unique indoor operating parameter, probably indoor temperature. A basic air-conditioning cycle is the operating cycle of a basic air-conditioning system. The basic air-conditioning cycle of this system. In summer mode at design load, recirculation air from the conditioned space, a worship hall, enters the packaged unit through the return grill at point. It is mixed with the required minimum amount of outdoor air at point o for acceptable indoor air quality and energy saving.

Basic Air-Conditioning Cycle — Winter Mode When the basic air-conditioning systems are operated in winter mode, their airconditioning cycles can be classified into the following four categories: In winter, for a fully occupied worship hall, if the heat loss is less than the space sensible cooling load, a cold air supply is required to offset the space sensible cooling load and maintain a desirable indoor environment as shown by the lower cycle in Usually, a humidifier is not used.

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Window and through-wall Room air conditioners come in two forms: unitary and packaged terminal (PTAC) systems. Unitary systems, the common one room air conditioners, sit in a window or wall opening, with interior controls. Interior air is cooled as a fan blows it over the evaporator. On the exterior the air is heated as a second fan blows it over the condenser. In this process, heat is drawn from the room and discharged to the environment. A large house or building may have several such units, permitting each room to be cooled separately. PTAC systems are also known as wall-split air conditioning systems or ductless systems. [21]These PTAC systems which are frequently used in hotels have two separate units (terminal packages), the evaporative unit on the interior and the condensing unit on the exterior, with tubing ing through the wall and connecting them. This minimizes the interior system footprint and allows each room to be adjusted independently. PTAC systems may be adapted to provide heating in cold weather, either directly by using an electric strip, gas or other heater, or by reversing the refrigerant flow to heat the interior and draw heat from the exterior air, converting the air conditioner into a heat pump. While room air conditioning provides maximum flexibility, when used to cool many rooms at a time it is generally more expensive than central air conditioning.

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An air conditioning unit

Split Systems C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Split-system air conditioners come in two forms: central and mini-split. In both types, the insideenvironment (evaporative) heat exchanger and fan is separated by some distance from the outside-environment (condensing unit) heat exchanger and fan. In central air conditioning, the inside heat-exchanger is typically placed inside the central furnace/AC unit of forced air heating system which is then used in the summer to distribute chilled air throughout a residence or commercial building. A mini-split system typically supplied chilled air to only a single space, and thus was sometimes referred to as split-system singlezone air conditioning. Today, however, one split-system compressor can supply chilled air to up to eight indoor units.[23] If the split system contains a heat pump, as is often the case, the system may be easily switched seasonally to supply heat instead of cold. Controls can be wall-mounted or handheld (the size of the remote control for a television).

Portable Units A portable air conditioner is one on wheels that can be easily transported inside a home or office. They are currently available with capacities of about 5,000–60,000 BTU/h (1,800–18,000 W

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output) and with and without electric-resistance heaters. Portable air conditioners are either evaporative or refrigerate. Portable refrigerative air conditioners come in two forms, split and hose. These compressorbased refrigerant systems are air-cooled, meaning they use air to exchange heat, in the same way as a car or typical household air conditioner does. Such a system dehumidifies the air as it cools it. It collects water condensed from the cooled air and produces hot air which must be vented outside the cooled area; doing so transfers heat from the air in the cooled area to the outside air. A portable split system has an indoor unit on wheels connected to an outdoor unit via flexible pipes, similar to a permanently fixed installed unit. Hose systems, which can be monoblock or air-to-air, are vented to the outside via air ducts. The monoblock type collects the water in a bucket or tray and stops when full. The air-toair type re-evaporates the water and discharges it through the ducted hose and can run continuously. A single-duct unit uses air from within the room to cool its condenser, and then vents it outside. This air is replaced by hot air from outside or other rooms, thus reducing the unit's effectiveness. Modern units might have a coefficient of performance (COP, sometimes called "efficiency") of approximately 3 (i.e., 1 kW of electricity will produce 3 kW of cooling). A dual-duct unit draws air to cool its condenser from outside instead of from inside the room, and thus is more effective than most single-duct units. Evaporative air coolers, sometimes called "swamp coolers", do not have a compressor or condenser. Liquid water is evaporated on the cooling fins, releasing the vapour into the cooled area. Evaporating water absorbs a significant amount of heat, the latent heat of vaporization, C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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cooling the air: humans and animals use the same mechanism to cool themselves by sweating. They have the advantage of needing no hoses to vent heat outside the cooled area, making them truly portable; and they are very cheap to install and use less energy than refrigerative air conditioners. Disadvantages are that unless ambient humidity is low (as in a dry climate) cooling is limited and the cooled air is very humid and can feel clammy. Also, they use a lot of water, which is often at a in the dry climates where they work best. A typical single hosed portable air conditioner can cool a room that is 475 sq ft (44.1 m2) or smaller and has at most a cooling power of 15,000 BTUs/h (4.3 kW). However, single hosed units cool a room less effectively than dual hosed as the air expelled from the room through the single hose creates negative pressure inside the room. Because of this, air (potentially warm air) from neighboring rooms is pulled into the room with the cooling unit to compensate.

Heat pumps "Heat pump" is a term for a type of air conditioner in which the refrigeration cycle can be reversed, producing heating instead of cooling in the indoor environment. They are also commonly referred to, and marketed as, a "reverse cycle air conditioner". Using an air conditioner in this way to produce heat is significantly more energy efficient than electric resistance heating. Some homeowners elect to have a heat pump system installed, which is simply a central air conditioner with heat pump functionality (the refrigeration cycle can be reversed in cold weather). When the heat pump is in heating mode, the indoor evaporator coil switches roles and becomes the condenser coil, producing heat. The outdoor condenser unit also switches roles to serve as the evaporator, and discharges cold air (colder than the ambient outdoor air). C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Heat pumps are more popular in milder winter climates where the temperature is frequently in the range of 40–55°F (4–13°C), because heat pumps become inefficient in more extreme cold. This is due to the problem of ice forming on the outdoor unit's heat exchanger coil, which blocks air flow over the coil. To compensate for this, the heat pump system must temporarily switch back into the regular air conditioning mode to switch the outdoor evaporator coil back to being the condenser coil, so that it can heat up and defrost. A heat pump system will therefore have a form of electric resistance heating in the indoor air path that is activated only in this mode in order to compensate for the temporary indoor air cooling, which would otherwise be uncomfortable in the winter. The icing problem becomes much more severe with lower outdoor temperatures, so heat pumps are commonly installed in tandem with a more conventional form of heating, such as a natural gas or oil furnace, which is used instead of the heat pump during harsher winter temperatures. In this case, the heat pump is used efficiently during the milder temperatures, and the system is switched to the conventional heat source when the outdoor temperature is lower. it also works on the basis of carnot cycle Absorption heat pumps are actually a kind of air-source heat pump, but they do not depend on electricity to power them. Instead, gas, solar power, or heated water is used as a main power source. Additionally, refrigerant is not used at all in the process. An absorption pump absorbs ammonia into water. Next, the water and ammonia mixture is depressurized to induce boiling, and the ammonia is boiled off, resulting in cooling. Some more expensive window air conditioning units have a true heat pump function. However, a window unit that has a "heat" selection is not necessarily a heat pump because some units use only electric resistance heat when heating is desired. A unit that has true heat pump functionality will be indicated its specifications by the term "heat pump". C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Uses Air-conditioning engineers broadly divide air-conditioning applications into what they call comfort and process applications. Comfort applications aim to provide a building indoor environment that remains relatively constant despite changes in external weather conditions or in internal heat loads. Air conditioning makes deep plan buildings feasible, for otherwise they would have to be built narrower or with light wells so that inner spaces received sufficient outdoor air via natural ventilation. Air conditioning also allows buildings to be taller, since wind speed increases significantly with altitude making natural ventilation impractical for very tall buildings. ] Comfort applications are quite different for various building types and may be categorized as: •

Commercial buildings, which are built for commerce, including offices, malls, shopping centers, restaurants, etc.

•

High-rise residential buildings, such as tall dormitories and apartment blocks

•

Industrial spaces where thermal comfort of workers is desired

•

Institutional buildings, which includes government buildings, hospitals, schools, etc.

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•

Low-rise residential buildings, including single-family houses, duplexes, and small apartment buildings

•

Sports stadiums: recently, stadiums have been built with air conditioning, such as the University of Phoenix Stadium and in Qatar for the 2022 FIFA World Cup.

The structural impact of an air conditioning unit will depend on the type and size of the unit. In addition to buildings, air conditioning can be used for many types of transportation, including motor-cars, buses and other land vehicles, trains, ships, aircraft, and spacecraft. Process applications aim to provide a suitable environment for a process being carried out, regardless of internal heat and humidity loads and external weather conditions. It is the needs of the process that determine conditions, not human preference. Process applications include these: •

Chemical and biological laboratories

•

Clean rooms for the production of integrated circuits , pharmaceuticals , and the like, in which very high levels of air cleanliness and control of temperature and humidity are required for the success of the process.

•

Environmental control of data centers

•

Facilities for breeding laboratory animals . Since many animals normally reproduce only in spring, holding them in rooms in which conditions mirror those of spring all year can cause them to reproduce year-round.

•

Food cooking and processing areas

•

Hospital operating theatres , in which air is filtered to high levels to reduce infection risk

and

the

humidity

controlled

to

limit

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patient

dehydration. Although temperatures are often in the comfort range, some specialist procedures, such as open heart surgery, require low temperatures (about

18

°C,

64

°F)

and

others,

such

as neonatal,

relatively

high

temperatures (about 28 °C, 82 °F). •

Industrial environments

•

Mining

•

Nuclear power facilities

•

Physical testing facilities

•

Plants and farm growing areas

•

Textile manufacturing

In both comfort and process applications, the objective may be to not only control temperature, but also humidity, air quality, and air movement from space to space.

Domestic use Air conditioning is common in the US, with 88% of new single-family homes constructed in 2011 including air conditioning, ranging from 99% in the South to 62% in the West. In Europe, home air conditioning is generally less common. Southern European countries such as Greece have seen a wide proliferation of home air-conditioning units in recent years. In another southern European country, Malta, it is estimated that around 55% of households have an air conditioner installed. In India AC sales have dropped by 40% due to higher costs and stricter energy efficiency regulations.

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Health Issues Air-conditioning systems can promote the growth and spread of microorganisms, such as Legionella pneumophila, the infectious agent responsible for Legionnaires' disease, or thermophilic actinomycetes; however, this is only prevalent in poorly maintained watercooling towers. As long as the cooling tower is kept clean (usually by means of a chlorine treatment), these health hazards can be avoided. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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Conversely, air conditioning (including filtration, humidification, cooling and disinfection) can be used to provide a clean, safe,hypoallergenic atmosphere in hospital operating rooms and other environments where an appropriate atmosphere is critical to patient safety and well-being. Air conditioning

can

have

cause dehydration. Air

a

negative

conditioning

effect may

on

skin,

drying

have

a

positive

it

out, and

effect

on

can

also

sufferers

of allergies and asthma. Prior to 1994, most automotive air conditioning systems used Dichlorodifluoromethane (R-12) as

a

refrigerant.

It

was

usually

sold

under

the brand

name Freon-12 and

is

a chlorofluorocarbon halomethane (CFC). The manufacture of R-12 was banned in many countries in 1994 because of environmental concerns, in compliance with the Montreal Protocol. The R-12 was replaced with R-134a refrigerant, which has a lower ozone depletion potential. Old R-12 systems can be retrofitted to R-134a by a complete flush and filter/dryer replacement to remove the mineral oil, which is not compatible with R-134a.

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Humidity Control

Air conditioning units outside a classroom building at the University of North Carolina in Chapel Hill, North Carolina Refrigeration air-conditioning equipment usually reduces the absolute humidity of the air processed by the system. The relatively cold (below the dewpoint) evaporator coil condenses water vapor from the processed air (much like an ice-cold drink will condense water on the outside of a glass), sending the water to a drain and removing water vapor from the cooled space and lowering the relative humidity in the room. Since humans perspire to provide natural cooling by the evaporation of perspiration from the skin, drier air (up to a point) improves the comfort provided. The comfort air conditioner is designed to create a 40% to 60% relative humidity in the occupied space. In food-retailing establishments, large open chiller cabinets act as highly effective air dehumidifying units. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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A specific type of air conditioner that is used only for dehumidifying is called adehumidifier. A dehumidifier is different from a regular air conditioner in that both the evaporator and condenser coils are placed in the same air path, and the entire unit is placed in the environment that is intended to be conditioned (in this case dehumidified), rather than requiring the condenser coil to be outdoors. Having the condenser coil in the same air path as the evaporator coil produces warm, dehumidified air. The evaporator (cold) coil is placed first in the air path, dehumidifying the air exactly as a regular air conditioner does. The air next es over the condenser coil, rewarming the now dehumidified air. Having the condenser coil in the main air path rather than in a separate, outdoor air path (as with a regular air conditioner) results in two consequences: the output air is warm rather than cold, and the unit is able to be placed anywhere in the environment to be conditioned, without a need to have the condenser outdoors. Unlike a regular air conditioner, a dehumidifier will actually heat a room just as an electric heater that draws the same amount of power (watts) as the dehumidifier would. A regular air conditioner transfers energy out of the room by means of the condenser coil, which is outside the room (outdoors). That is, the room can be considered a thermodynamic system from which energy is transferred to the external environment. Conversely, with a dehumidifier, no energy is transferred out of the thermodynamic system (room) because the air conditioning unit (dehumidifier) is entirely inside the room. Therefore all of the power consumed by the dehumidifier is energy that is input into the thermodynamic system (the room) and remains in the room (as heat). In addition, if the condensed water has been removed from the room, the amount of heat needed to boil that water has been added to the room. This is the inverse of adding water to the room with an evaporative cooler.

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Dehumidifiers are commonly used in cold, damp climates to prevent mold growth indoors, especially in basements. They are also used to protect sensitive equipment from the adverse effects of excessive humidity in tropical countries. The engineering of physical and thermodynamic properties of gas–vapor mixtures is called psychrometrics.

Energy In a thermodynamically closed system, any power dissipated into the system that is being maintained at a set temperature (which is a standard mode of operation for modern air conditioners) requires that the rate of energy removal by the air conditioner increase. This increase has the effect that, for each unit of energy input into the system (say to power a light bulb in the closed system), the air conditioner removes that energy. In order to do so, the air conditioner must increase its power consumption by the inverse of its "efficiency" (coefficient of performance) times the amount of power dissipated into the system. As an example, assume that inside the closed system a 100 W heating element is activated, and the air conditioner has an coefficient of performance of 200%. The air conditioner's power consumption will increase by 50 W to compensate for this, thus making the 100 W heating element cost a total of 150 W of power. C ONTINEN TAL INS T IT UT E OF ENG IN EER IN G AND TEC HNOLOG Y

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It is typical for air conditioners to operate at "efficiencies" of significantly greater than 100%. However, it may be noted that the input electrical energy is of higher thermodynamic quality (lower entropy) than the output thermal energy (heat energy). Air conditioner equipment power in the U.S. is often described in of "tons of refrigeration". A ton of refrigeration is approximately equal to the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period. The value is defined as 12,000 BTU per hour, or 3517 watts.[16] Residential central air systems are usually from 1 to 5 tons (3 to 20 kilowatts (kW)) in capacity.

Bibliography • Amber Enterprises Pvt. Ltd • Engineer Guidance • Research

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