vehicle air conditioning

8/2/2019 Vehicle Air Conditioning

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MUKESHPATELSCHOOLOFTECHNOLOGYMANAGEMENT

&ENGINEERING

SHIRPUR,DIST. DHULIA(M.S)-425405.

Seminar Report On: -

PASSENGER VEHICLE AIR CONDITIONING

SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE

2NDYEARB.TECH. TRIMESTERV

BY

AKSHAY KUMAR CHANDEL

Roll No: 601

(SAP ID)

20112012

DEPARTMENT OFMECHANICALENGINEERING


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CERTFICATE

This is to certify that the seminar entitled Passenger vehicle Air Conditioning has

been submitted by AKSHAY KUMAR CHANDEL under the guidance of Prof.

RAJESH PATIL in partial fulfillment of the requirements of the degree of Bachelorof Technology in Mechanical Engineering of MPSTME, NMIMS University,

Shirpur during the academic year 2011-2012 (Trimester-V).

DATE:

PLACE: Shirpur

Guide H.O.D Associate Dean

Prof. Rajesh Patil Prof. Vishal Fegade Dr. M.V.Deshpande


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Preface

This paper describes steps and procedures necessary to achieve a successful CAR AIR

CONDITIONING. A topic which I am going to discuss includes basic components of car air

conditioning such as Compressor, Condenser, Receiver drier, Thermostat valve, Evaporator. I am

also going to discuss about how Air conditioner works in a Car. What are the main functions of

its components. What are advantages and disadvantages of Air conditioner in a Car. What are

common failures of Air conditioner in a car. What are uses and applications of Car air

conditioning. Apart from it I am also going to discuss about its types and also companies of Air

conditioner which is more preferable in vehicles. I have covered 7 chapters on PASSENGER

VEHICLE AIR CONDITIONING 1st chapter describes about vehicle air conditioning about

HVAC i.e. heating ventilation and air conditioning& its advantages and disadvantages. 2nd

chapter describes about the history & analysis of passenger vehicle air conditioning.3rd chapter

describes about the working of vehicle air conditioning, working of its main components.4 th

chapter describes about the impact of vehicle air conditioning on fuel economy and opportunities

to reduce air conditioning loads and some conclusions.5th chapter describes about bus air

conditioning its refrigeration cycle and its working.6th chapter describes about research and

development in vehicle air conditioning.7th chapter describes about some tips for optimal

operation of car air conditioning. And after that some references from where I collect some of

these stuffs.


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Abstract

Today, as we drive our automobiles, a great many of us, can enjoy the same comfort levels that

we are accustomed to at home and at work. With the push of a button or the slide of a lever, we

make the seamless transition from heating to cooling and back again without ever wonderinghow this change occurs. The introduction of the air conditioner has literally raised the bars for

luxury cars. Air conditioners only help to make the journey a smoother and better one. With the

growth of technology today air conditioners have an Automatic Temperature Control set-up

system which makes it more dependable than the older vacuum and thermostatic creations.

Earlier, most of the cars were designed with half open body and small tyres. During summers the

only air-conditioners were the natural breeze. Later when the car manufacturers started building

cars with closed body. With a car hood, the temperature in side the cabin turned very hot. The

car manufacturers tried many things as they made vents in the car floor, but it did not do any

good as it started inviting dust and dirt rather than cool air. Like this, the desire to get a cool

interior gave birth to many ideas.
http://www.carazoo.com/autonews/0804200801http://www.carazoo.com/autonews/0804200801http://www.carazoo.com/autonews/0804200801


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INDEX

Sr. no. Topic/Chapter no. Page no.

1.

2.

3.

4.

5.

6.

7.

INTRODUCTION OF VAC

ORIGIN OF VAC

WORKING OF VAC

IMPACT OF VAC ON FUEL

ECONOMY

BUS AIR CONDITIONING

R&D OF VAC

TIPS FOR OPTIMAL FOR YOU VAC

7-9

10-11

12-19

20-24

25-27

28-29

30-31


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LIST OF FIGURES

Sr. no. Figure Page no.

1.1

1.2

3.1

3.2

3.3

3.4

3.6

3.7

3.8

3.9

5.2

FIRST LOOK OF VAC

HAVC

WORKING OF VAC

COMPRESSER

CONDENSER

EVAPORATOR

ORIFICE TUBE

THERMAL EXPANSION VALVE

RECIEVER DRIVER

ACCUMULATOR

BUS AIR CONDITIONING

7

8

12

13

13

14

16

17

18

19

25

LIST OF TABLE

Sr.no. Topic Page no.

1. IMPACT ON FUEL ECONOMY 22


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Chapter 1 INTRODUCTION

1.1Introduction to vehicle air conditioning

Fig 1: First look of VAC

Today, as we drive our automobiles, a great many of us, can enjoy the same comfort levels that

we are accustomed to at home and at work. With the push of a button or the slide of a lever, we

make the seamless transition from heating to cooling and back again without ever wondering

how this change occurs. That is, unless something goes awry. Invention of the car air

conditioning system in the 1940's many things have undergone a change. The introduction of the

air conditioner has literally raised the bars for luxury cars. Air conditioners only help to make the

journey a smoother and better one. With the growth of technology today air conditioners have an

Automatic Temperature Control set-up system which makes it more dependable than the older

vacuum and thermostatic creations. Computers ensure the comfort of the driver and the

passenger's maintaining just about the right temperature inside a car. Using of cars air


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conditioner conservatively helps us go green because it helps us in consuming fuel and in turn it

saves our money at the pump. It also helps us to diminish the emission of ozone-depleting carbon

dioxide and other harmful greenhouse gases.

1.2HAVC- Heating ventilation &Air conditioning

The heating, ventilation, and airconditioning system is used to control theclimate of a vehicles interior. It is referredto as the HVAC system and it is designedto allow a source of fresh air into thevehicle, as well as tailor interiortemperature to suit the comfort needs of

the occupants. The HVAC system alsoperforms a vital safety roll by providing ameans to clear ice, fog and moisture fromthe vehicle's windshield and interior glass.Fresh air enters the vehicle through vents in the area of the base of the windshield. The air isdrawn into HVAC module by the blower motor. The air is then routed to the heater core to bewarmed or through the air conditioning evaporator to be cooled. It is then directed by air flowcontrols to the area requested by the operator. The air can be discharged to the windshield, indefroster mode, to the floor, in heater mode or through dash vents in A/C or vent position. Somevehicles offer a bi-level setting on the HVAC control panel which will cause air to be dischargedfrom both the dash vents and the floor vents at the same time.

Warming of the vehicles interior is accomplished by using the heat generated from the engine.Hot coolant is circulated through a radiator like device called a heater core that is mounted in theHVAC module. Air is warmed when it is directed through the heater core by absorbing heat fromthe coolant. The air can be blended with cooler outside air to provide various temperaturesettings for the vehicles interior. A refrigeration system provides a means of cooling and de-humidifying the interior of a vehicle. Air is drawn through the evaporator and is both cooled andde-humidified by the removal of heat and moisture during the refrigeration process. Know as airconditioning, the refrigeration system operation is similar for all vehicles.Basic air conditioningoperation uses the principals of latent heat to achieve cooling and de-humidification of air.Latent heat refers to the temperature properties when a substance is changed from one form to

another. For example, the freezing point of water is 32F but 32F is also the melting point ofwater. When water is changing from liquid to solid form (water to ice), it must release some heatin order to make that transition. The heat released is absorbed by the surrounding air, causing theair to be warmed. When water changes from a solid to liquid (ice to water), it must remove heatfrom the air aid in the process. This causes that air to become cooler. It is the same process thatallows a drink to be cooled by placing ice in a cup. Heat is removed from the surrounding liquidby the melting of the ice. Because water both freezes and melts at the same temperature.


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1.3Advantages & Disadvantages of passenger vehicle air conditioning1.3.1 Advantages

a) Efficient cool in air summers.b) Warm dehumidified air in winter easily demists steamed up windows.c) Pleasant and odour free vehicle atmosphere at all times.d) Drivers are more alert and have better visibility when window demisting becomes

necessary

e) Filters pollutants/airborne particles in pollen helping allergy sufferers.f) At highway speeds, vehicle air conditioning can lower greenhouse gas output compared

to open window driving, which increases fuel consumption due aerodynamic drag.

1.3.2 DisadvantagesWhen air expands in the engine it cools dramatically and must be heated to ambient

temperature using a heat exchanger. The heating is necessary in order to obtain a significant

fraction of the theoretical energy output. The heat exchanger can be problematic: while it

performs a similar task to an intercooler for an internal combustion engine, the temperature

difference between the incoming air and the working gas is smaller. In heating the stored air,

the device gets very cold and may ice up in cool, moist climates.

This also leads to the necessity of completely dehydrating the compressed air. If any humidity

subsists in the compressed air, the engine will stop due to inner icing. Removing the humidity

completely requires even additional energy that cannot be reused and is lost.
http://en.wikipedia.org/wiki/Intercoolerhttp://en.wikipedia.org/wiki/Intercoolerhttp://en.wikipedia.org/wiki/Intercooler


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Chapter 2 ORIGIN OF VEHICLE AIR CONDITIONING

2.1 History

Cars, since its birth represent luxury and lavish lifestyle and has come a long way with numerous

mechanical advancement and inventions. The concurrent development in the automobile sector

has differentiated the modern day car in many ways from their old legendary counterparts.

In early days, cars were not much adorned with accessories nor are they so technically advanced

like the present day cars which come fitted with sophisticated safety features, entertainment

systems, and improved mechanics.

The two most momentous progresses among the luxurious improvement were the evolution of

the car audio system and air-conditioning systems, the history of which is not only interesting but

also quite amusing.

Earlier, most of the cars were designed with half open body and small tyres. During summers the

only air-conditioners were the natural breeze. Later when the car manufacturers started building

cars with closed body. With a car hood, the temperature in side the cabin turned very hot. The

car manufacturers tried many things as they made vents in the car floor, but it did not do anygood as it started inviting dust and dirt rather than cool air. Like this, the desire to get a cool

interior gave birth to many ideas.

2.2 Analysis

In 1884, William Whiteley prepared an experiment where he placed blocks of ice in a container

under horse cart and puffed air inside with the help of a fan attached to the axle. This inspiration

was later followed by an evaporative cooling system. The temperature-reducing effect of air

passing over water was adopted by a company called Nash and was christened as Weather Eye.

It was in the year 1939, Packard (an Americanluxury carbrand built by the Packard Motor Car)

was the first car with an actual refrigeration system. This cooling system consisted of a large

evaporator, called the 'cooling coil,' which occupied the complete trunk space. Only the blower
http://www.carazoo.com/autonews/0804200801http://www.carazoo.com/autonews/0804200801http://www.carazoo.com/article/1004200801http://www.carazoo.com/article/1004200801http://www.carazoo.com/article/1004200801http://www.carazoo.com/article/1004200801http://www.carazoo.com/autonews/0804200801


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switch had a control. With this, the luxury car manufacturer promoted its product with a caption

saying, Forget the heat this summer in the only air-conditioned car in the world.It was then

followed by another car marque Cadillac in 1941 that rolled out 300 air-conditioned cars. The

only disadvantage of these early air-conditioning systems carried was that there was no

compressor clutch and as a result, the pump was on when the engine was running. To turn off the

system, one had to stop the car, get out, open the hood, and remove the belt.Then Cadillac

introduced all new high-tech air-conditioner mounted with control. Again, there was a drawback

as these controls were placed on the rear package shelf. The driver had to go up to the back seat

to shut the system off. This was one-step better than reaching under the hood.The Harrison

Radiator Division of General Motors developed the first efficient, affordable air-conditioning

system that went on for the mass production. This new cooling feature was available as an

option on all 1954 Pontiacs with V8 engines. It carried a two-cylinder reciprocating compressor,

and an all-brazed condenser. The system was also enhanced with magnetic clutch, where when

the A/C was not in use, no power was required to drive the compressor and this resulted in better

performance and fuel economy.

Until 70s the air conditioning remained as rare option but then air-conditioned car became the

trend in 70s and 80s. With innovations and latest designs, the cooling systems were further

improved.

Today, heating and air-conditioning systems are very competent. Contemporary Automatic

Temperature Control set-ups are more reliable than the older vacuum and thermostatic creations.

The cooling systems ensure that both the passenger and driver have a comfortable drive.

Car air conditioners have seen incrementally significant improvements with the passage of time

and are more efficient as well as affordable. The range of varieties has increased as well along

with mass acceptability.
http://www.carazoo.com/autonews/2804200801http://www.carazoo.com/autonews/2804200801http://www.carazoo.com/autonews/2804200801


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Chapter 3 WORKING OF VEHICLE AIR CONDITIONING

3.1 Most common components of vehicle air conditioning

Fig 3: Working of VAC

Vehicles are found to have primarily three different types of air conditioning systems. While

each of the three types differ, the concept and design are very similar to one another. The most

common components which make up these automotive systems are the following:

COMPRESSOR,CONDENSER,EVAPORATOR,ORIFICETUBE,THERMALEXPANSION

VALVE ,RECEIVER-DRIER,ACCUMULATOR.if your car has an Orifice tube, it will not

have a Thermal Expansion Valve as these two devices serve the same purpose. Also, you will

either have a Receiver-Dryer or an Accumulator, but not both.
http://www.familycar.com/ac1.htm#CONDENSERhttp://www.familycar.com/ac1.htm#CONDENSERhttp://www.familycar.com/ac1.htm#CONDENSERhttp://www.familycar.com/ac1.htm#EVAPORATORhttp://www.familycar.com/ac1.htm#EVAPORATORhttp://www.familycar.com/ac1.htm#EVAPORATORhttp://www.familycar.com/ac1.htm#ORIFICE%20TUBEhttp://www.familycar.com/ac1.htm#ORIFICE%20TUBEhttp://www.familycar.com/ac1.htm#ORIFICE%20TUBEhttp://www.familycar.com/ac1.htm#ORIFICE%20TUBEhttp://www.familycar.com/ac1.htm#ORIFICE%20TUBEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#RECEIVER-DRIERhttp://www.familycar.com/ac1.htm#RECEIVER-DRIERhttp://www.familycar.com/ac1.htm#RECEIVER-DRIERhttp://www.familycar.com/ac1.htm#RECEIVER-DRIERhttp://www.familycar.com/ac1.htm#ACCUMULATORhttp://www.familycar.com/ac1.htm#ACCUMULATORhttp://www.familycar.com/ac1.htm#ACCUMULATORhttp://www.familycar.com/ac1.htm#RECEIVER-DRIERhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#THERMAL%20EXPANSION%20VALVEhttp://www.familycar.com/ac1.htm#ORIFICE%20TUBEhttp://www.familycar.com/ac1.htm#EVAPORATORhttp://www.familycar.com/ac1.htm#CONDENSER


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3.2 Compressor

Fig 4: Compressor

Commonly referred to as the heart of the system, the compressor is a belt driven pump that is

fastened to the engine. It is responsible for compressing and transferring refrigerant gas.

The A/C system is split into two sides, a high pressure side and a low pressure side; defined as

discharge and suction. Since the compressor is basically a pump, it must have an intake side and

a discharge side. The intake, or suction side, draws in refrigerant gas from the outlet of the

evaporator. In some cases it does this via the accumulator.

Once the refrigerant is drawn into the suction side, it is compressed and sent to the condenser,

where it can then transfer the heat that is absorbed from the inside of the vehicle.

3.3 Condenser

Fig 5: Condenser
http://www.familycar.com/ac1.htm#CONDENSERhttp://www.familycar.com/ac1.htm#CONDENSERhttp://www.familycar.com/ac1.htm#CONDENSER


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This is the area in which heat dissipation occurs. The condenser, in many cases, will have much

the same appearance as the radiator in your car as the two have very similar functions. The

condenser is designed to radiate heat. Its location is usually in front of the radiator, but in some

cases, due to aerodynamic improvements to the body of a vehicle, its location may differ.

Condensers must have good air flow anytime the system is in operation. On rear wheel drive

vehicles, this is usually accomplished by taking advantage of your existing engine's cooling fan.

On front wheel drive vehicles, condenser air flow is supplemented with one or more electric

cooling fan(s).

As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As

the gas cools, it condenses and exits the bottom of the condenser as a high pressure liquid. \

3.4 Evaporator

Fig 6: Evaporator

Located inside the vehicle, the evaporator serves as the heat absorption component. The

evaporator provides several functions. Its primary duty is to remove heat from the inside of your

vehicle. A secondary benefit is dehumidification. As warmer air travels through the aluminumfins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust

and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days

you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is

perfectly normal.


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The ideal temperature of the evaporator is 32 Fahrenheit or 0 Celsius. Refrigerant enters the

bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator

fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant

begins to boil, it can absorb large amounts of heat. This heat is then carried off with the

refrigerant to the outside of the vehicle. Several other components work in conjunction with the

evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32 F.

Temperature and pressure regulating devices must be used to control its temperature. While there

are many variations of devices used, their main functions are the same; keeping pressure in the

evaporator low and keeping the evaporator from freezing; A frozen evaporator coil will not

absorb as much heat.

3.5 Pressure regulating devices

Controlling the evaporator temperature can be accomplished by controlling refrigerant pressure

and flow into the evaporator. Many variations of pressure regulators have been introduced since

the 1940's. Listed below, are the most commonly found.

3.6 Orifice tube


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Fig 7: Orifice tube

The orifice tube, probably the most commonly used, can be found in most GM and Ford models.

It is located in the inlet tube of the evaporator, or in the liquid line, somewhere between the

outlet of the condenser and the inlet of the evaporator. This point can be found in a properly

functioning system by locating the area between the outlet of the condenser and the inlet of the

evaporator that suddenly makes the change from hot to cold. You should then see small dimples

placed in the line that keep the orifice tube from moving. Most of the orifice tubes in use today

measure approximately three inches in length and consist of a small brass tube, surrounded by

plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to

become clogged with small debris. While inexpensive, usually between three to five dollars, the

labor to replace one involves recovering the refrigerant, opening the system up, replacing theorifice tube, evacuating and then recharging. With this in mind, it might make sense to install a

larger pre filter in front of the orifice tube to minimize the risk of of this problem reoccurring.

Some Ford models have a permanently affixed orifice tube in the liquid line. These can be cut

out and replaced with a combination filter/orifice assembly.


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3.7 Thermal expansion valve

Fig 8: Thermal expansion valve

Another common refrigerant regulator is the thermal expansion valve, or TXV. Commonly used

on import and aftermarket systems. This type of valve can sense both temperature and pressure,

and is very efficient at regulating refrigerant flow to the evaporator. Several variations of this

valve are commonly found. Another example of a thermal expansion valve is Chrysler's "H

block" type. This type of valve is usually located at the firewall, between the evaporator inlet and

outlet tubes and the liquid and suction lines. These types of valves, although efficient, have some

disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with

debris, but also have small moving parts that may stick and malfunction due to corrosion.

3.8 Receiver drier


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Fig 9: Receiver drier

The receiver-drier is used on the high side of systems that use a thermal expansion valve. This

type of metering valve requires liquid refrigerant. To ensure that the valve gets liquid refrigerant,

a receiver is used. The primary function of the receiver-drier is to separate gas and liquid. The

secondary purpose is to remove moisture and filter out dirt. The receiver-drier usually has a sight

glass in the top. This sight glass is often used to charge the system. Under normal operating

conditions, vapor bubbles should not be visible in the sight glass. The use of the sight glass to

charge the system is not recommended in R-134a systems as cloudiness and oil that has

separated from the refrigerant can be mistaken for bubbles. This type of mistake can lead to a

dangerous overcharged condition. There are variations of receiver-driers and several differentdesiccant materials are in use. Some of the moisture removing desiccants found within are not

compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the

receiver-drier. Newer receiver-driers use desiccant type XH-7 and are compatible with both R-12

and R-134a refrigerants.

3.9 Accumulator


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Fig 10: Accumulator

Accumulators are used on systems that accommodate an orifice tube to meter refrigerants into

the evaporator. It is connected directly to the evaporator outlet and stores excess liquid

refrigerant. Introduction of liquid refrigerant into a compressor can do serious damage.

Compressors are designed to compress gas not liquid. The chief role of the accumulator is to

isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers,

also remove debris and moisture from a system. It is a good idea to replace the accumulator each

time the system is opened up for major repair and anytime moisture and/or debris is of concern.

Moisture is enemy number one for your A/C system. Moisture in a system mixes with refrigerant

and forms a corrosive acid. When in doubt, it may be to your advantage to change the

Accumulator or receiver in your system.


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Chapter 4 IMPACT OF VEHICLE AIR CONDITIONING IN

FUEL ECONOMY & ITS CONCLUSION

4.1Impact on fuel economy

Vehicle air-conditioning can significantly impact fuel economy and tailpipe emissions of

conventional and hybrid electric vehicles (HEV) and reduce electric vehicle (EV) range. In

addition, a new U. S. emissions procedure, called the Supplemental Federal Test Procedure

(SFTP), has provided the motivation for reducing the size of vehicle air-conditioning Systems in

the United States. The SFTP will measure tailpipe emissions with the air-conditioning system

operating. Current air-conditioning systems can reduce the fuel economy of high fuel-economy

vehicles by about 50% and reduce the fuel economy of todays mid-sized vehicles by more than

20% while increasing NOx by nearly 80% and CO by 70%.

The power necessary to operate a vehicle air-conditioning compressor is significant. It can be

greater than the engine power required to move a mid-sized vehicle at a constant speed of 56

km/h (35 mph). A 400-W load on a conventional engine can decrease the fuel economy by about

0.4 km/L (1 mpg). The United States could save over $6 billion annually if all the light-dutyvehicles in the country achieved a modest 0.4-km/L (1-mpg) increase in fuel economy. The size

of the air-conditioning system is related to the peak thermal load in the vehicle. The peak thermal

load is generally

related to the maximum temperature the cabin will reach while soaking in the sun. The thermal

load can be further reduced by using more efficient distribution of the treated air as well as using

more efficient equipment (such as by using waste heat to provide cooling). We have considered a

variety of technologies to reduce climate control loads such as advanced glazing, heated/cooled

seats, parked car ventilation, recirculation strategies, and air cleaning1,2. In this paper, we

present the benefits of solar-reflective glazing, the impact of treating large volumes of outside

air, and thermal comfort. The peak load can be reduced by reducing the solar gain into the

vehicle and by using ambient air to cool the hot vehicle cabin. Solar energy enters the vehicle

and raises the cabin soak temperature through two paths: the windows and the opaque


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components of the vehicle, such as the roof. Although it may seem intuitive to insulate the

vehicle roof to reduce the solar gain, roof insulation can actually increase the cabin temperature,

because the roof (particularly if it is light-colored) serves as a heat rejection path as the cabin

temperature rises.

An automobile is used, on average, about 249 hours annually3 or about 41 minutes per day, 365

days a year. Estimates of air-conditioning use range from 107 to 121 hours per year4 or 43% to

49% of vehicle usage. Actual use varies considerably depending on such factors as climate, time

of day, time of year, type of vehicle (including vehicle color), outdoor/indoor parking. Occupant

clothing, recent occupant activity levels, length

of trip, vehicle speed, and personal preference. Gasoline use in the U.S. in 1998 was about 473

billion liters (125 billion gallons) for on-road use5 including gasoline-fueled

commercial trucks. In 1998 there were about 203.6 million cars and light duty trucks on the

road6 including sport utility vehicles and minivans. This resulted in an average fuel use of 2316

liters (612 gallons) of gasoline per vehicle, or about 8.3 km/l (19.6 mpg) for an average of

19,300 km/yr (12,000 miles/year) at an average speed of 77.5 km/h (48.2 mph).(assuming 249hours of driving time per year). Each vehicle, on average, uses about 235 liters (62 gallons) of

gasoline annually for operating the air-conditioning system. Fischer has estimated that the annual

fuel required to carry theadditional weight of the air-conditioning system is about 12.7 liters (3.4gallons) per vehicle. Given the above assumptions, the estimated total fuel used for airconditioning, if 80% of the vehicles have working air-conditioning systems, is about 40 billionliters (10.6 billion gallons) of gasoline annually. Until recently, little has motivated U.S. automakers to find ways to reduce the impact of air-conditioning on fuel economy and emissions.But a new emissions regulation, the Supplemental Federal Test Procedure7 (SFTP), will include

air conditioning as part of the emissions testing procedure. Table 1 shows the SFTPimplementation schedule and thespecifications are given in Table 2. The test procedure consistsof the current emissions test (called the Federal TestProcedure or FTP), an air-conditioning test(SC03), and a high-speed, high-acceleration test (US06). The SFTP applies to vehicles with agross vehicle weight under 2608 kg (5750 lb). The air-conditioning portion of the SFTP will

contribute 37% of the total tailpipe emissions. The SC03 is conducted at 35C (95F), 850W/m2, and 100 grains of water per poundof dry air.


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Although the SFTP is not used to measure fuel economy, reducing the weight of a mid-sized

vehicles air-conditioning system by 9.1 kg (20 lb) results in about a 0.04 km/L (0.1 mpg)

increase in fuel economy on the current combined

City/highway test.

FTP SC03 US06

Time (s) 1877 594 600

Max speed, km/h 91.2 88.2 129.2

Max acceleration, km/h/s 5.8 12.2 8.9

Distance, km 17.8 5.8 12.9

Contribution to total

emissions value

35% 37% 28%

Table 1: Impact on fuel economy

4.2 Opportunities to reduce air conditioning loads

Vehicle air-conditioning systems in the United States are often sized to provide adequate cooldown time for a peak cooling load in Phoenix, Arizona, with a solar load of 1 kW/m2 and 49C

(120F) ambient temperature. Such conditions can lead to surface temperatures of more than

121C (250F) and cabin air temperatures higher than 82C (180F). The peak load can be two

to four times greater than the steady-state cooling load. The cabin soak temperature must be

lowered to reduce the size of the air-conditioning system.

4.3 Advanced glazing

The Federal Motor Vehicle Safety Standards require that all glazing in passenger cars have a

photopically-weighted transmissivity of 70% while light trucks, SUVs, and minivans have no

transmissivity requirement for glazing behind the front seats. If transmissivity requirements for

passenger cars were the same as SUVs and minivans, then more efficient glazing could be used


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resulting in less fuel for air-conditioning. The transmissivity of the glazing is measured

perpendicular to the glazing. If the standards were to measure the transmissivity parallel to the

road, inline with the drivers normal eye sight, then angularly selective glazings could be used to

keep solar energy out of vehicles.

4.4 Recirculated Air

After reducing the peak thermal load and the solar gain, the next most important approach to

minimizing air conditioning loads is to reduce the amount of outside air brought in for

ventilation. It is more effective to condition recirculated cabin air than to treat very cold or very

hot air from outside.

4.5 Conclusion

The air conditioning system is the single largest auxiliary load on a vehicle by nearly an order of

magnitude. Current air conditioning systems reduce the fuel economy of conventional vehicles,

thus incremental improvements can have a significant near-term benefit because of the large

number of new cars sold each year. For high fuel economy vehicles, current air conditioning

systems have a completely unacceptable impact on fuel economy. For example, conventional air-conditioning loads can reduce EV range and HEV fuel economy by nearly 40% depending on the

size of the air-conditioner and the driving cycle. The peak cabin soak temperature must be

reduced if a smaller air-conditioning system is to be used. Advanced glazing and cabin

ventilation during soak conditions are effective ways to reduce the peak cabin temperature. To

fully understand the thermal impact of vehicle modifications, effective modeling and testing

must be conducted. We are continuing to investigate advanced glazing and ventilation

techniques, but it is apparent that great opportunities exist to improve EV and HEV performance

while reducing fuel consumption and improving air quality. A significant benefit could be

achieved if the Federal Motor Vehicle Safety Standards were modified to allow lower

transmissivity for glazing behind the front seats in all light duty vehicles and if transmissivity

requirements were measured parallel to the drivers eyesight and maintained at current levels in

that direction. It is clear that significant reductions in automotive auxiliary loads are needed,


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making tomorrows vehicles safer, quieter, and more fuel efficient, while making passengers

comfortable more quickly. New U.S. emissions standards are also providing the impetus for

evaluating new climate control de signs and approaches. Vehicle climate control can be reduced

in many ways-some of which can be readily implemented in todays vehicles, and others that

will require more development. Increasing vehicle efficiencies and decreasing polluting

emissions will go a long way toward achieving the national and global goals of reduced

dependency on foreign oil and improved air quality.

.


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Chapter 5 BUS AIR CONDITIONING

5.1 Definition

Bus Air Conditioning is the cooling, dehumidification, and filtration of the air within the

passenger compartment of your vehicle.

5.2 The bus air refrigeration cycle

The Bus Air Conditioning Refrigeration Cycle

Fig 11: Bus air conditioning


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The Thermostat, located in the interior of the vehicle, calls for cooling Based on a

signal from the thermostat, by means of an inter connecting electrical system, the

electromagnetic clutch on the compressor engages.

Once engaged, the compressor then circulates refrigerant through the system

through inter connecting hoses.

Refrigerant, existing as a gas, and containing the heat from the passenger

compartment, is pumped by the compressor, under high pressure, into the condenser

coil.

Fans pull cool air through the condenser coil, which contains refrigerant existing as

a hot gas.

The refrigerant undergoes a change-of-state, from a gas to a liquid, through a

process called condensation.

During condensation, the hot gas rejects its heat load to the outside air, which was

transferred from the passenger compartment, into the refrigerant, by the evaporator.

The refrigerant now exists as a cool liquid, which passes through the filter drier,

which removing moisture and impurities, and then the sight glass, which enables

visual inspection of the refrigerant.

The cool liquid is then pumped to the evaporator where an expansion valve meters

the refrigerant into the evaporator coil.Fans pull passenger compartment air through a filter, which removes particulate

matter, then passes the cleaned air through the evaporator coil.

The refrigerant undergoes a change of pressure from high to low, and a

corresponding change-of-state from a liquid to a gas, through a process called

evaporation. During evaporation, the heat contained in the air in the passenger

compartment is absorbed by the gaseous refrigerant. A warm air passes through the

evaporator coil, moisture condenses, and is collected and drained to the exterior of

the vehicle, The hot gas is then suctioned back to the compressor and pumped to the

condenser.

Todays buses and coaches rely increasingly on effective air conditioning systems to

meet growing passenger demand for a higher level of comfort. But simply installing


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a good air conditioning system is not enough to guarantee efficient operation;

equally important is a perfect match between the A/C system and the vehicle.

We adopt a total approach, from professional development and engineering support

for constructors through to quality service contracts for European bus and coach

operators. The result is modern and efficient A/C systems, fit for purpose and with

trouble-free operation en route. In addition, weight and electrical capacity

limitations on the road network mean that DENSOs lightweight Bus Air

Conditioning offers a significant edge over other systems: saving on fuel without

compromising on performance. DENSOs global expertise in automotive air

conditioning systems also gives us an in-depth understanding of aftermarket

requirements: OE quality matched components with low maintenance costs. Ourprogramme includes Spotcoolers for driver comfort, as well as full-size Integrated

Systems and EBAC Roof-Mounted Systems for the passenger compartment. In

short, DENSO Air Conditioning systems provide high cooling capacity with the

lowest cost of ownership in the market lowest cost of ownership in the market.


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Chapter 6 RESEARCH & DEVELOPMENT IN

VEHICLE AIR CONDITIONING

6.1 Who developed first car air conditioner

Mitsubishi Heavy Industries, Ltd. developed the worlds first car air-conditioning

filter for decomposing and inactivating pollen, mites and other substances that

cause allergies (allergens) accumulating on the filter through the action of an

enzyme and urea (called Bio-clear Filter) to improve the air quality in the cabin.

The rapid rise in sales of home air purifiers and home electric appliance

manufacturers introduction of a sanitizing function into their residential air-

conditioners in recent years indicate that users are concerned about their own health

and are becoming interested in improving the quality of air in their own rooms.

Furthermore, a questionnaire about the air quality in a cabin completed by our

companys employees indicated that they are strongly interested in the sanitizing

and removal of pollen and other allergens as well as in dust removal and

deodorization.

Noting this growing concern about health and cleanliness, then Mitsubishi Heavy

Industries, Ltd. a filter with a new function for a car air conditioner

(called Bio-clear Filter). This new filter is designed to purge the air in a cabin,

based on new techniques developed by Mitsubishi Heavy Industries Ltd. for

decomposing and inactivating pollen, mites and other substances that cause allergies

(called allergens hereafter) that accumulate on the filters for its residential air-

conditioners.

6.2 Problems of conventional filter

The conventional filter for a car air-conditioner is usually located upstream of the

blower fan in the air conditioner unit. The air inside the cabin and the air

outside it both flow through the filter while the air-conditioner is running. The dust,

pollen, mites, etc. in the air are deposited inside the filter However, some of the

deposited dust, pollen, mites, etc. is dispersed again in the cabin due to the vibration


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of the moving car, the wind that gets into the filter (especially when the wind

volume is at maximum), etc., which again deteriorate the air in the cabin.

Improvement of air quality by Bio-clear Filter

The Bio-clear Filter not only collects pollen and mites but also decomposes andinactivates the allergens collected on the filter. Even if part of the collected

pollen and mites disperses again in the cabin, their allergens have decomposed and

inactivated so that the air quality in the cabin has improved.

6.3 Improvement of quality by bio-clear filterThe Bio-clear Filter not only collects pollen and mites but also decomposes and

inactivates the allergens collected on the filter. Even if part of the collected

pollen and mites disperses again in the cabin, their allergens have decomposed and

inactivated so that the air quality in the cabin has improved.

6.4 Conclusions

worlds first Bio-clear filter for a car air-conditioner which can decompose

and inactivate pollen, mites and other allergens, to improve the quality of air in the

cabin and checked its adaptability and resistance to the conditions under which it is

used. The Bio-clear Filter was incorporated first into the Bloom Edition Series

special editions for COLT, ek WAGON and PAJERO MINI

released in May 2005 and was well received by users.

The Japan Automotive Industry Association is promoting voluntary efforts to

reduce volatile Organic Compounds (VOC) inside cabin. In line with this,

Mitsubishi are now developing an additional function to reduce VOC inside cabin to

improve the cabin ambience even further.


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Chapter 7 TIPS FOR OPTIMAL OPERATION OF YOUR AIR

CAR CONDITIONING

7.1 Some tips

Temperatures over 90 degrees and high humidity can challenge your vehicles air conditioning

system. Here are five easy tips from the Mobile Air Conditioning Society (MACS) Worldwide to

keep you and your passengers cool on the road.

7.1.1

If possible, leave the windows down slightly on hot days to reduce heat build-up. An A/C system

works by removing heat, so the cooler the interior is to start with, the easier and faster the A/Cwill do its job.

7.1.2

When you get in the car, open all the windows completely, or even open the doors, for a moment

to vent the hot interior air quickly.

7.1.3

When you first turn the A/C on, set the controls to MAX or REC and use highest blower speed.

This moves the greatest volume of air and re-circulates it for even faster cool-down. As soon as

you are comfortable, switch the system to NORM or OUTSIDE or FRESH, and select a lower

fan speed. The lower blower speed produces colder the air from the system.


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7.1.4

Does your cool air have a bad odor, perhaps like dirty socks or a gym locker? Remember to set

the system to the OUTSIDE air mode (not REC) frequently to help prevent or lessen this

problem.

7.1.5

Automatic Temperature Control systems operate differently than manual systems. Read your

owners manual to gain understanding of exactly how your system works.

With most automatic systems, the quickest cool-down comes by setting the temperature as low

as it will go at first, then adjusting it later to occupant comfort.

REFERENCES

Cooling by Evaporation (Letter to John Lining).

History of Air Conditioning Source: Jones Jr., Malcolm. "Air Conditioning".

http://www.greenyour.com/transportation/car/car-driving/tips/use-your-cars-air-conditioner-

conservatively.

http://automobiles.mapsofindia.com/car-accessories/car-air-conditioning.html

www.arap.org/docs/vac.html


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