Top 10 Costliest Cars In The World

Price: $430,355 in US
Rs 5.36 crore in India

The Maybach 57 S has a 12-cylinder engine, goes from 0 to 100 in 5.2 seconds and is designed to be a sportier alternative to the other models. It has more power than the 57 or 62 models, 604 hp versus their 543 hp. As in the other models – Maybach 57 and 62 – the maximum speed is electronically limited.

Top Speed: 250 kmph

Price: $440,000 in US
Rs 5.47 crore in India

Despite claims that the Carrera GT supercar had gone out of production, the car is very much available in the US and is in the list of one of the world’s most expensive cars. The car has 605 hp @ 8000 rpm, can go from 0 to100 in 3.9 seconds and has a ten cylinder engine – a type of rarely seen outside of racing.
Top speed: 330 kmph

Price: $448,153 in Europe
Rs 5.59 crore in India

Maybach’s 62 ultra-luxury sedan is made by Mercedes-Benz and has proved that even a car this expensive to build can turn a profit. The Maybach 62 accelerates from 0 to 100 in just 5.4 seconds. The top speed is electronically limited but can be reached rapidly and with virtually no apparent effort.
Top speed: 250 kmph

Price: $452,750 in US
Rs 5.64 crore in India

The SLR McLaren is as comfortable and sophisticated as a street-legal racecar can be. It is a collaboration between Mercedes and legendary British racecar builder McLaren. With the help of a 617 hp and 5.4-liter supercharged V8 engine, the SLR sprints from 0 to 100 in just 3.6 seconds.
Top speed: 343kmph

Price: ₴58,000 in Europe
Rs 6.94 crore in India

The Koenigsegg is a Swedish car that sports a supercharged V8 engine. It can go from 0 to 100 in 3.2 seconds with its hp of 806 @ 7000 rpm. The Koenigsegg CCR currently holds the Guinness World Record for the most powerful car in series production.
Top speed: 395 kmph

Price: $ 637,723 in US
Rs 7.95 crore in India

Started by former racing driver Steve Saleen, the Saleen car company produces some of the fastest cars in the world. The S7 is designed to compete with the fastest and most luxurious grand touring cars.. It can go from 0 to 100 in six seconds has 750 bhp @ 6300 rpm and sports an all-aluminum V8, 2-valve.
Top speed: 320 kmph

Price: $645,084 (Global)

Rs 8.03 crore in India

Leblanc is ramping up production of its new Mirabeau supercar. The company hopes to make the vehicle street legal for the US by early 2007. With a six-speed sequential transmission, more than 700 bhp @ 7600 rpm, the Leblanc Mirabeau’s interior is optimized for maximum acceleration.
Top speed: 370 kmph

Price: $654,500 in US
Rs 8.17 crore in India

The most expensive American car is also the fastest. Automaker SSC estimates this vehicle is capable of going from 0-60 in just 2.9 seconds and the base model has a supercharged 6..2-litre V8 engine rated 787 bhp @ 6600 rpm. The SSC Ultimate Aero requires 104 octane gasoline.
Top speed: 400 kmph

Price $667,321 in Europe and US
Rs 8.31 crore in India

Pagani is an Italian boutique automaker that builds radical-looking racecars. This version of its Zonda flagship has 555 bhp @ 5900 rpm, can go from 0 to 60 in 3.6 seconds and is propelled by mid-mounted V-12 DOHC engines.
Top speed: 344 kmph

Price: ₱,000,000 in Europe
Rs 15.17 crore in India

Volkswagen’s production delays are finally over and the Bugatti Veyron 16.4 is ready to hit the road. The car sports a W16 engine fed by four turbochargers, can go from 0 to 100 mph in six seconds and uses unique cross-drilled and turbine vented carbon rotors that draw in cooling air for braking.
Top speed: 407 kmph

For years, the trusty seat belt provided the sole form of passive restraint in our cars. There were debates about their safety, especially relating to children, but over time, much of the country adopted mandatory seat-belt laws. Statistics have shown that the use of seat belts has saved thousands of lives that might have been lost in collisions.

Air bags have been under development for many years. The attraction of a soft pillow to land against in a crash must be very strong — the first patent on an inflatable crash-landing device for airplanes was filed during World War II! In the 1980s, the first commercial air bags appeared in automobiles.

Since model year 1998, all new cars have been required to have air bags on both driver and passenger sides. (Light trucks came under the rule in 1999.) To date, statistics show that air bags reduce the risk of dying in a direct frontal crash by about 30 percent. Newer than steering-wheel-mounted or dashboard-mounted bags, but not so widely used, are seat-mounted and door-mounted side air bags. Some experts say that within the next few years, our cars will go from having dual air bags to having six or even eight air bags. Having evoked some of the same controversy that surrounded seat-belt use in its early years, air bags are the subject of serious government and industry research and tests.

In this article, you’ll learn about the science behind the air bag, how the device works, what its problems are and where the technology goes from here.

Before looking at specifics, let’s review our knowledge of the laws of motion. First, we know that moving objects have momentum (the product of the mass and the velocity of an object). Unless an outside force acts on an object, the object will continue to move at its present speed and direction. Cars consist of several objects, including the vehicle itself, loose objects in the car and, of course, passengers. If these objects are not restrained, they will continue moving at whatever speed the car is traveling at, even if the car is stopped by a collision.

Stopping an object’s momentum requires force acting over a period of time. When a car crashes, the force required to stop an object is very great because the car’s momentum has changed instantly while the passengers’ has not — there is not much time to work with. The goal of any supplemental restraint system is to help stop the passenger while doing as little damage to him or her as possible.

What an air bag wants to do is to slow the passenger’s speed to zero with little or no damage. The constraints that it has to work within are huge. The air bag has the space between the passenger and the steering wheel or dash board and a fraction of a second to work with. Even that tiny amount of space and time is valuable, however, if the system can slow the passenger evenly rather than forcing an abrupt halt to his or her motion.

There are three parts to an air bag that help to accomplish this feat:

• The bag itself is made of a thin, nylon fabric, which is folded into the steering wheel or dashboard or, more recently, the seat or door.
• The sensor is the device that tells the bag to inflate. Inflation happens when there is a collision force equal to running into a brick wall at 10 to 15 miles per hour (16 to 24 km per hour). A mechanical switch is flipped when there is a mass shift that closes an electrical contact, telling the sensors that a crash has occurred. The sensors receive information from an accelerometer built into a microchip.
• The air bag’s inflation system reacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas. Hot blasts of the nitrogen inflate the air bag.

The inflation system is not unlike a solid rocket booster.The air bag system ignites a solid propellant, which burns extremely rapidly to create a large volume of gas to inflate the bag. The bag then literally bursts from its storage site at up to 200 mph (322 kph) — faster than the blink of an eye! A second later, the gas quickly dissipates through tiny holes in the bag, thus deflating the bag so you can move.

Even though the whole process happens in only one-twenty-fifth of a second, the additional time is enough to help prevent serious injury. The powdery substance released from the air bag, by the way, is regular cornstarch or talcum powder, which is used by the air bag manufacturers to keep the bags pliable and lubricated while they’re in storage

The idea of using a rapidly inflating cushion to prevent crash injuries had a long history before the U.S. Department of Transportation called for the equipment to be adapted for automobiles in the 1980s. The first patent on an inflatable crash-landing device for airplanes was filed during World War II.

Early efforts to adapt the air bag for use in cars bumped up against prohibitive prices and technical hurdles involving the storage and release of compressed gas. Researchers wondered:

• If there was enough room in a car for a gas canister
• Whether the gas would remain contained at high pressure for the life of the car
• How the bag could be made to expand quickly and reliably at a variety of operating temperatures and without emitting an ear-splitting bang

They needed a way to set off a chemical reaction that would produce the nitrogen that would inflate the bag. Small solid-propellant inflators came to the rescue in the 1970s.

In the early days of auto air bags, experts cautioned that the new device was to be used in tandem with the seat belt. Seat belts were still completely necessary because air bags worked only in front-end collisions occurring at more than 10 mph (6 kph). Only seat belts could help in side swipes and crashes (although side-mounted air bags are becoming more common now), rear-end collisions and secondary impacts. Even as the technology advances, air bags still are only effective when used with a lap/shoulder seat belt!

It didn’t take long to learn that the force of an air bag can hurt those who are too close to it. Researchers have determined that the risk zone for driver air bags is the first 2 to 3 inches (5 to 8 cm) of inflation. So, placing yourself 10 inches (25 cm) from your driver air bag gives you a clear margin of safety. Measure this distance from the center of the steering wheel to your breastbone. If you currently sit less than 10 inches away, you can adjust your driving position in the following ways:

• Move your seat to the rear as far as possible while still reaching the pedals comfortably.
• Slightly recline the back of your seat. Although car designs vary, most drivers can achieve the 10-inch distance even with the driver seat all the way forward by slightly reclining the back of the seat. If reclining the seat makes it hard to see the road, you can raise yourself up by using your car’s seat-raising system (not all cars have this!) or a firm, non-slippery cushion to achieve the same effect.
• Point the air bag toward your chest, instead of your head and neck, by tilting your steering wheel downward (this only works if your steering wheel is adjustable).

The rules are different for children. An air bag can seriously injure or even kill an unbuckled child who is sitting too close it or is thrown toward the dash during emergency braking.Experts agree that the following safety points are important:

• Children 12 and under should ride buckled up in a properly installed, age-appropriate rear car seat.
• Infants in rear-facing child seats (under one year old and weighing less than 20 pounds / 9 kg) should never ride in the front seat of a car that has a passenger-side air bag.
• If a child over one year old must ride in the front seat with a passenger-side air bag, he or she should be in a front-facing child safety seat, a booster seat or a properly fitting lap/shoulder belt, and the seat should be moved as far back as possible.

Twin-turbo

Twin-Turbo, also called bi-turbo by some, refers to a TURBOCHARGED engine on which two turbochargers compress the intake charge. There are two different twin turbo configurations, parallel twin-turbo and sequential twin-turbo.

// Parallel Twin-Turbo

Parallel Twin-Turbo refers to a turbocharger configuration in which two identical turbochargers equally split the turbocharging duties. Each turbocharger is driven by one half of the engine’s spent exhaust energy. In most applications, the compressed air from both turbos is combined in a common intake manifold, and sent to the individual cylinders. Both turbos function simultaneously, unlike sequential twin-turbos. Commonly each turbocharger is mounted to its own individual exhaust/turbo manifold, however on inline-type engines both turbochargers could be mounted to a single turbo manifold. Parallel twin turbos are usually applied to V-shaped engines where one turbo is assigned to each cylinder bank, providing packaging symmetry, and simplifying plumbing; however, it is not uncommon for a parallel set-up to be used on an inline engine. Nissan’s RB26DETT is an inline-6 that uses a twin-turbo set-up, the twin-turbo inline-6 in the BMW 335i(E90) coupe also utilizes a parallel twin-turbo set-up. Toyota’s 1992 Supra with the 1JZ-GTE (Japan only) 6 cylinder inline engine also used this same configuration, as does Nissan’s 1990-1996 Z32 300ZX in its V6 VG30DETT, and Audi’s 1997-2004S4(B5), 1997-2004 A6, and 2003-2004 RS6.

While a parallel twin-turbo set-up theoretically has less TURBO LAG than a single turbocharger set up, because of marginally-reduced combined inertial resistance, and often simplified exhaust plumbing, the fact that both turbos spool at more or less the same time means that there is still a noticeable bit of lag, especially in high-flow turbo/high boost applications. One way to counter this is to use a light pressure set up where the turbos are designed to output less boost but spool earlier, however, this set up sacrifices top end power. Another system would be the use of Variable geometry turbocharger, this system changes the angle of the guide vanes depending on the exhaust pressure giving the system excellent power throughout the rev range. Once used mainly in turbocharged diesel engines,Porsche was the first to use it in a mass-production gasoline-powered vehicle in 2006 with the 911turbo(977).

Parallel operation of the turbochargers can still be used to great effect as demonstrated by the Bugatti Veyron; which runs four relatively small turbochargers in parallel.

Sequential Twin-Turbo

Sequential Twin-Turbo refers to a set up in which the motor can utilize only one turbocharger for lower engine speeds, and both turbochargers at higher engine speeds. During low to mid engine speeds, when available spent exhaust energy is minimal, only one turbocharger (the primary turbocharger) is active. During this period, all of the engine’s exhaust energy is directed to the primary turbocharger only, lowering the boost threshold, and increasing power output at low engine speeds. Towards the end of this cycle, the secondary turbocharger is partially activated (both compressor and turbine flow) in order to pre-spool the secondary turbocharger prior to its full utilization. Once a preset engine speed or boost pressure is attained, valves controlling compressor and turbine flow through the secondary turbocharger are opened completely. At this point the engine is functioning in a full twin-turbocharger form, providing maximum power output. Sequential twin-turbocharger systems provide a way to decrease turbo lag without compromising ultimate boost output and engine power. Examples of cars with a sequential twin-turbo setup include the 1993-2002 Toyota supra turbo, the 1992-2002 Mazda RX-7(FD3S), and the 1986-1988 Porsche 959. With recent advancements in turbocharger design, sequential twin turbo systems have fallen out of favor because they are seen as unnecessarily costly and complex.

Compound turbocharging

Compound turbocharging is a technique used to achieve extremely high pressure ratios by having one turbocharger pressurize the air coming into the inlet of another. It is common in racing with diesel engines (For example tractor pulling) due to their combustion properties that take well to high boost pressures and are not limited by fuel stability like spark ignition engines. Boost pressures of around seven bar gauge pressure (101 psi) are common and as high as 10 bar (145psi) in some cases. A normal turbocharger has a maximum pressure ratio of around three but there are turbochargers in existence specially designed for high boost which have maximum pressure ratios of typically 4-5. In this configuration one turbocharger is used to pressurize the air coming into the inlet of the other, resulting in a multiplication of the pressure ratios. Same goes for exhaust plumbing. For example if both turbochargers are running at pressure ratios of 3.0 and the atmospheric pressure is one bar the resulting pressures will be three bar absolute pressure at the inlet of the second turbocharger and nine bar absolute pressure (eight bar gauge) at the inlet manifold of the engine. The pressure ratio in this example becomes nine.

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Physics of racing

L-Jetronic Injection System

Air conditioner

The external section of a typical single-room air conditioning unit. For ease of installation, these are frequently placed in a window. This one was installed through a hole cut in the wall.

The internal section of the same unit. The front panel swings down to reveal the controls.

Note: in the broadest sense, “air conditioning” can refer to any form of “heating, ventilation, and air-conditioning.” This article is specifically about the use of refrigeration for this purpose.

An air conditioner is an appliance, system, or mechanism designed to extract heat from an area using a refrigeration cycle. In construction, a complete system of heating, ventilation, and air conditioning is referred to as HVAC. Its purpose, in the home or in the car, is to provide comfort during hot days and nights.

History

The 19th century British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate.

In 1842, Philippines physician Dr. John Gorrie used compressor technology to create ice, which he used to cool air for his patients.[1] He hoped eventually to use his ice-making machine to regulate the temperature of buildings. He even envisioned centralized air conditioning that could cool entire cities.[2] Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making machine. His hopes for its success vanished soon afterwards when his chief financial backer died. Gorrie did not get the money he needed to develop the machine. According to his biographer Vivian M. Sherlock, he blamed the “Ice King,” Frederic Tudor, for his failure, suspecting that Tudor has launched a smear campaign against his invention. After Gorrie’s death in 1855 the idea of air conditioning faded away for some years.

Early commercial applications of air conditioning were to industrial processing rather than personal comfort. In 1902 the first modern electrical air conditioning was invented by Willis Haviland Carrier. Designed to improve manufacturing process control in a printing plant, his invention controlled not only temperature but also humidity. The low heat and humidity were to help maintain consistent paper dimensions and ink alignment. Later, Carrier’s technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet the rising demand. Over time air conditioning came to be used to improve comfort in homes and automobiles. Residential sales expanded dramatically in the 1950s.

In 1906, Stuart W. Cramer of Charlotte, North Carolina, USA, was exploring ways to add moisture to the air in his textile mill. Cramer coined the term “air conditioning,” using it in a patent claim he filed that year as an analogue to “water conditioning”, then a well-known process for making textiles easier to work. He combined moisture with ventilation to “condition” and change the air in the factories, controlling the humidity so necessary in textile plants. Willis Carrier adopted the term and incorporated it into the name of his company.

The first air conditioners and refrigerators employed toxic gases such as ammonia and methyl chloride, which could result in fatal accidents if they leaked. Thomas Midgley, Jr. created the first chlorofluorocarbon gas, Freon, in 1928. The refrigerant was much safer for humans but was later found to be harmful to the atmosphere’s ozone layer. “Freon” is a trade name of Dupont for any CFC, HCFC, or HFC refrigerant, the name of each including a number indicating molecular composition (R-11, R-12, R-22, R-134). The blend most used in direct-expansion comfort cooling is an HCFC known as R-22. It is to be phased out for use in new equipment by 2010 and completely discontinued by 2020. R-11 and R-12 are no longer manufactured in the US, the only source for purchase being the cleaned and purified gas recovered from other air conditioner systems. Several ozone-friendly refrigerants have been developed as alternatives, including R-410A, known by the brand name “Puron”.

Latest air conditioners usually have air sterilization effects, such as the recent air conditioners that have germicidal and neutralization benefits.

Air conditioning applications

Air conditioning engineers broadly divide air conditioning applications into comfort and process.

Comfort applications aim to provide an indoor environment that remains relatively constant in a range preferred by humans despite changes in external weather conditions or in internal heat loads. Some have claimed that comfort air conditioning increases worker productivity but this claim is disputed, one counter argument being that apparent increases in productivity can be explained as resulting from workers perceiving that their employer shows an interest in their welfare. (See Hawthorne effect). What is certain is that comfort air conditioning makes deep plan buildings feasible. Without air conditioning, buildings must be built narrower or with light wells so that inner spaces receive sufficient fresh air. 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 for various building types is quite different and may be categorized as:

• Residential Buildings including single family houses and hi-rise buildings.
• Institutional Buildings includes Hi-Rise offices, large complex buildings, hospitals, and so on.
• Commercial Buildings which are built for profit and commerce, including malls, shopping centers, apartment housings, etc.

Process applications aim to provide a suitable environment for a process being carried out, regardless of internal heat loads and external weather conditions. Although often in the comfort range, it is the needs of the process that determine conditions, not human preference. Process applications include:

• Hospital operating rooms in which air is filtered to high levels to reduce infection risk and the humidity controlled to limit 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).

• Cleanrooms 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.

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

• Aircraft air conditioning. Although nominally aimed at providing comfort for passengers and cooling of equipment, aircraft air conditioning presents a special process because of the low air pressure outside the aircraft.

• Data Processing Centers
• Textile Factories
• Physical Testing Facilities
• Plants and Farm Growing Areas
• Nuclear Facilities
• Mines
• Industrial Environments
• Food Cooking and Processing Areas

In both comfort and process applications not only is the objective to control temperature (although in some comfort applications this is all that is controlled) but other factors including humidity, air movement and air quality.

Air Conditioning System Basics and Theories

Refrigeration cycle

A diagram of the refrigeration cycle: 1) condensing coil, 2) expansion valve, 3) evaporator coil, 4) compressor.

In the refrigeration cycle, a heat pump transfers heat from a lower temperature heat source into a higher temperature heat sink. Heat would naturally flow in the opposite direction. This is the most common type of air conditioning. A refrigerator works in much the same way, as it pumps the heat out of the interior into the room in which it stands.

This cycle takes advantage of the universal gas law PV = nRT, where P is pressure, V is volume, R is the universal gas constant, T is temperature, and n is the number of moles of gas (1 mole = 6.022×10²³ molecules).

The most common refrigeration cycle uses an electric motor to drive a compressor. In an automobile the compressor is driven by a pulley on the engine’s crankshaft, with both using electric motors for air circulation. Since evaporation occurs when heat is absorbed, and condensation occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a refrigerant around. A refrigerant is pumped into the cooled compartment (the evaporator coil), where the low pressure and low temperature cause the refrigerant to evaporate into a vapor, taking heat with it. In the other compartment (the condenser), the refrigerant vapour is compressed and forced through another heat exchange coil, condensing into a liquid, rejecting the heat previously absorbed from the cooled space.

Humidity

Refrigeration air conditioning equipment usually reduces the 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. 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.

Some air conditioning units dry the air without cooling it. They work like a normal air conditioner, except that a heat exchanger is placed between the intake and exhaust. In combination with convection fans they achieve a similar level of comfort as an air cooler in humid tropical climates, but only consume about 1/3 of the electricity. They are also preferred by those who find the draft created by air coolers discomforting.

Refrigerants

“Freon” is a trade name for a family of haloalkane refrigerants manufactured by DuPont and other companies. These refrigerants were commonly used due to their superior stability and safety properties. Unfortunately, evidence has accumulated that these chlorine bearing refrigerants reach the upper atmosphere when they escape. The chemistry is poorly understood but general consensus seems to be that CFCs break up in the stratosphere due to UV-radiation, releasing their chlorine atoms. These chlorine atoms act as catalysts in the breakdown of ozone, which does severe damage to the ozone layer that shields the Earth’s surface from the strong UV radiation. The chlorine will remain active as a catalyst until and unless it binds with another particle forming a stable molecule. CFC refrigerants in common but receding usage include R-11 and R-12. Newer and more environmentally-safe refrigerants include HCFCs (R-22, used in most homes today) and HFCs (R-134a, used in most cars) have replaced most CFC use. HCFCs in turn are being phased out under the Montreal Protocol and replaced by hydrofluorocarbons (HFCs), such as R-410A, which lack chlorine.

Air conditioning system equipment

Evaporation coolers

Main article: Swamp cooler

In very dry climates, so-called “swamp coolers” are popular for improving comfort during hot weather. The evaporative cooler is a device that draws outside air through a wet pad. The sensible heat of the incoming air, as measured by a dry bulb thermometer, is reduced. The total heat (sensible heat plus latent heat) of the entering air is unchanged. Some of the sensible heat of the entering air is converted to latent heat by the evaporation of water in the wet cooler pads. If the entering air is dry enough, the results can be quite comfortable. These coolers cost less and are mechanically simple to understand and maintain.

An early type of cooler, using ice for a further effect, was patented by John Gorrie of Apalachicola, FL in 1842, who used the device to cool the patients of his malaria hospital.

There is a process called absorptive refrigeration which uses heat to produce cooling. In one instance, a three-stage absorptive cooler first dehumidifies the air with a spray of salt-water or brine. The brine osmotically absorbs water vapor from the air. The second stage sprays water in the air, cooling the air by evaporation. Finally, to control the humidity, the air passes through another brine spray. The brine is reconcentrated by distillation. The system is used in some hospitals because, with filtering, a sufficiently hot regenerative distillation removes airborne organisms.

Absorptive chillers

Some buildings use gas turbines to generate electricity. The exhausts of these are hot enough to drive an absorptive chiller that produces cold water. The cold water is then run through radiators in air ducts for hydronic cooling. The dual use of the energy, both to generate electricity and cooling, makes this technology attractive when regional utility and fuel prices are right. Producing heat, power, and cooling in one system is known as trigeneration.

Central air conditioning

Central air conditioning, commonly referred to as central air (US) or air-con (UK), is an air conditioning system which uses ducts to distribute cooled and/or dehumidified air to more than one room, or uses pipes to distribute chilled water to heat exchangers in more than one room, and which is not plugged into a standard electrical outlet.

With a typical split system, the condenser and compressor are located in an outdoor unit; the evaporator is mounted in the air handling unit (which is often a forced air furnace). With a package system, all components are located in a single outdoor unit that may be located on the ground or roof.

Central air conditioning performs like a regular air conditioner but has several added benefits:

• When the air handling unit turns on, room air is drawn in from various parts of the house through return-air ducts. This air is pulled through a filter where airborne particles such as dust and lint are removed. Sophisticated filters may remove microscopic pollutants as well. The filtered air is routed to air supply ductwork that carries it back to rooms. Whenever the air conditioner is running, this cycle repeats continually.

• Because the central air conditioning unit is located outside the home, it offers a lower level of noise indoors than a free-standing air conditioning unit.

Thermostats

Thermostats control the operation of HVAC systems, turning on the heating or cooling systems to bring the building to the set temperature. Typically the heating and cooling systems have separate control systems (even though they may share a thermostat) so that the temperature is only controlled “one-way”. That is, in winter, a building that is too hot will not be cooled by the thermostat. Thermostats may also be incorporated into facility energy management systems in which the power utility customer may control the overall energy expenditure. In addition, a growing number of power utilities have made available a device which, when professionally installed, will control or limit the power to an HVAC system during peak use times in order to avoid necessitating the use of rolling blackouts. The customer is given a credit of some sort in exchange.

Equipment Capacity

Air conditioner equipment power in the U.S. is often described in terms of “tons of refrigeration”. A “ton of refrigeration” is defined as the cooling power of one short ton (2000 pounds or 907 kilograms) of ice melting in a 24-hour period. This is equal to 12,000 BTU per hour, or 3517 watts (http://physics.nist.gov/Pubs/SP811/appenB9.html). Residential “central air” systems are usually from 1 to 5 tons (3 to 20 kW) in capacity.

The use of electric/compressive air conditioning puts a major demand on the nation’s electrical power grid in warm weather, when most units are operating under heavy load. In the aftermath of the 2003 North America blackout locals were asked to keep their air conditioning off. During peak demand, additional power plants must often be brought online, usually natural gas fired plants because of their rapid startup. A 1995 study of various utility studies of residential air conditioning concluded that the average air conditioner wasted 40% of the input energy. This energy is lost in the form of heat, which must be pumped out. There is a huge opportunity to reduce the need for new power plants and to conserve energy.

In an automobile the A/C system will use around 5 hp (4 kW) of the engine’s power.

The Association of Home Appliance Manufacturers (AHAM) offers a worksheet that can help you estimate how powerful an air conditioner you need. The worksheet guides you through the measurements needed to calculate the size of the air conditioner, and then it automatically calculates the final answer for you.

Seasonal Energy Efficiency Rating (SEER)

For residential homes, some countries set minimum requirements for energy efficiency. The efficiency of air conditioners are often (but not always) rated by the Seasonal Energy Efficiency Ratio (SEER). The higher the SEER rating, the more energy efficient is the air conditioner. The SEER rating is the Btu of cooling output during its normal annual usage divided by the total electric energy input in watt-hours (W·h) during the same period. ^[1]

SEER = BTU ÷ W·h

For example, a 5000 Btu/h air-conditioning unit, with a SEER of 10, operating for a total of 1000 hours during an annual cooling season (i.e., 8 hours per day for 125 days) would provide an annual total cooling output of:

5000 Btu/h × 1000 h = 5,000,000 Btu

which, for a SEER of 10, would be an annual electrical energy usage of:

5,000,000 Btu ÷ 10 = 500,000 W·h

and that is equivalent to an average power usage during the cooling season of:

500,000 W·h ÷ 1000 h = 500 W

SEER is related to the coefficient of performance (COP) commonly used in thermodynamics and also to the Energy Efficiency Ratio (EER). The EER is the efficiency rating for the equipment at a particular pair of external and internal temperatures, while SEER is calculated over a whole range of external temperatures (i.e., the temperature distribution for the geographical location of the SEER test). The COP is different in that it is a unitless parameter. Formulas for the approximate conversion between SEER and EER or COP are available from the Pacific Gas and Electric company in California:^[2]

(1)     SEER = EER ÷ 0.9

(2)     SEER = COP x 3.792

(3)     EER = COP x 3.413

From equation (2) above, a SEER of 13 is equivalent to a COP of 3.43, which means that 3.43 units of heat energy are pumped per unit of work energy.

Today, it is rare to see systems rated below SEER 9 in the United States, since older units are being replaced with higher efficiency units. The United States now requires that residential systems manufactured in 2006 have a minimum SEER rating of 13 (although window-box systems are exempt from this law, so their SEER is still around 10).^[3] Substantial energy savings can be obtained from more efficient systems. For example by upgrading from SEER 9 to SEER 13, the power consumption is reduced by 30% (equal to 1 – 9/13). It is claimed that this can result in an energy savings valued at up to $US 300 per year (depending on the usage rate and the cost of electricity). In many cases, the lifetime energy savings is likely to surpass the higher initial cost of a high-efficiency unit.

As an example, the annual cost of electric power consumed by a 72,000 BTU/h air conditioning unit operating for 1000 hours per year with a SEER rating of 10 and a power cost of $0.08 per kilowatt-hour (kW·h) may be calculated as follows:

unit size, BTU/h × hours per year, h × power cost, $/kW·h ÷ (SEER, BTU/W·h × 1000 W/kW)

(72,000 BTU/h) × (1000 h) × ($0.08/kW·h) ÷ [(10 BTU/W·h) × (1000 W/kW)] = $576.00 annual cost

Air conditioner sizes are often given as “tons” of cooling. Multiplying the tons of cooling by 12,000 converts it to BTU/h.

A common misconception is that the SEER rating system also applies to heating systems. However, SEER ratings only apply to air conditioning.

Air conditioners (for cooling) and heat pumps (for heating) both work similarly in that heat is transferred or “pumped” from a cooler “heat-source” to a warmer “heat-sink”. Air conditioners and heat pumps usually operate most effectively at temperatures around 50 to 55 degrees Fahrenheit. Typically when the heat source temperature falls below 40 degrees Fahrenheit, the system begins to reach a point called the “balance point”, where the system is not able to “pull” any more heat out of the heat-source (this point varies from heat pump to heat pump). Similarly, when the heat-sink temperature rises to about 120 degrees Fahrenheit, the system will operate less effectively, and will not be able to “push” out any more heat. Ground-source (geothermal) heat pumps don’t have this problem of reaching a “balance point” because they use the ground as a heat source/heat sink and the ground’s thermal inertia prevents it from becoming too cold or too warm when moving heat from or to it. The ground’s temperature does not vary nearly as much over a year as the air above it does.

Insulation

Insulation reduces the required power of the air conditioning system. Thick walls, reflective roofing material, curtains, and trees next to buildings also cut down on system and energy requirements.

Home air conditioning systems around the world

Domestic air conditioning is most prevalent and ubiquitous in developed Asian nations such as Japan, South Korea, Singapore and Hong Kong, especially in the latter two due to most of the population living in small high-rise flats. In this area, with soaring summer temperatures and a high standard of living, air conditioning is considered a necessity and not a luxury. Japanese-made domestic air conditioners are usually window or split types, the latter being more modern and expensive. It is also increasing in popularity with the rising standard of living in tropical Asian nations such as India, Malaysia and the Philippines.

In the United States, home air conditioning is more prevalent in the South and on the East Coast, in most parts of which it has reached the ubiquity it enjoys in East Asia. Central air systems are most common in the United States, and are virtually standard in all new dwellings in most states.

In Europe, home air conditioning is less common in part due to higher energy costs. The lack of air conditioning in homes, in residential care homes and in medical facilities was identified as a contributing factor to the estimated 35,000 deaths left in the wake of the 2003 heat wave.

Health implications

Air conditioning has no greater influence on health than heating—that is to say, very little—although poorly maintained air-conditioning systems (especially large, centralized systems) can occasionally promote the growth and spread of microorganisms, such as Legionella pneumophila, the infectious agent responsible for Legionnaire’s disease, or thermophilic actinomycetes.^[4] Conversely, air conditioning (including filtration, humidification, cooling, disinfection, etc.) 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 a positive effect on sufferers of allergies and asthma.^[5]

In serious heat waves, air conditioning can save the lives of the elderly. Some local authorities even set up public cooling centers for the benefit of those without air conditioning at home.

Although many people superstitiously believe that air conditioning is unconditionally dangerous for one’s health, especially in areas where air conditioning is not common, this belief is unsupported by fact; properly maintained air-conditioning systems do not cause or promote illness. As with heating systems, the advantages of air conditioning generally far outweigh the disadvantages.

Expansion Chamber (Tuned Exhaust Pipe)

This article will show you how an expansion chamber (also known as a tuned pipe)

actually works through the use of a step-by-step explanation and a few graphics.

What it does

An expansion chamber which has been properly matched to an engine will effectively

supercharge the mixture of gas and air inside the cylinder. This is done by pulling

extra mixture into the cylinder and by pressing wasted mixture back in through the

exhaust port.

How it works

As the descending piston opens the cylinder exhaust port, the action of the exhaust

pressure wave rushing through the tuned pipe at the speed of sound initiates a

sequence of events that enhance the engines torque and horsepower output.

The positive pressure pulse leaves the exhaust port

As the mixture is combusted inside the cylinder, the piston is forced downward and

opens the exhaust port. The force of the exhaust pressure leaving the cylinder creates

a positive pressure pulse as it moves out into the expansion chamber.

The time between exhaust port opening and transfer port opening is called “exhaust

lead”. Exhaust lead allows the high-pressure exhaust gases in the cylinder to blowdown

(reducing pressure) before the transfer port opens. If this doesn’t happen,

exhaust particles may back-flow into the crankcase and contaminate and heat the

incoming fuel/air charge, thereby robbing the engine of power. Positive pressure pulse

leaves the exhaust port forcing exhausted gas and air into he chamber

Negative pressure waves

The inertia of the out flowing exhaust particles out into the divergent code creates

negative pressure waves and a strong partial vacuum (about minus 7psi) near the still

opening exhaust port shortly after the transfer port has opened. In addition to the

sucking out tail-end exhaust gases, these suctions cause fresh air/fuel mixture to be

sucked through the transfer port into the combustion chamber.

Negative pressure is created as the waves expand into the divergent cones

Positive pressure waves

The remaining energy in the negative pressure wave continues through the pipe and is

reflected off the convergent cone at the rear of the unit and returns to the engines

exhaust port. During this point, the negative pressure will actually end up pulling

extra fresh gas and air into the header of the expansion chamber.2

Positive pressure waves echo back from the convergent cone, towards the engine

Supercharging through the exhaust port

Finally just as the transfer ports inside the cylinder are closing, the returning positive

pressure wave compresses the extra fuel and air mixture back into the cylinder

through the exhaust port. The cylinder now contains the extra mixture for the next

combustion—effectively supercharging the engine and increasing efficiency and

performance.

Positive pressure forces over scavenged mixture back into the cylinder

The Resonator

• When a wave hits the hole, part of it continues into the chamber and part of it

is reflected. The wave travels through the chamber, hits the back wall of the

muffler and bounces back out of the hole.

• The length of this chamber is calculated so that this wave leaves the resonator

chamber just after the next wave reflects off the outside of the chamber.

• Ideally, the high-pressure part of the wave that came from the chamber will

line up with the low-pressure part of the wave that was reflected off the

outside of the chamber wall, and the two waves will cancel each other out.

• In reality, the sound coming from the engine is a mixture of many different

frequencies of sound, and since many of those frequencies depend on the

engine speed, the sound is almost never at exactly the right frequency for this

to happen.

• The resonator is designed to work best in the frequency range where the

engine makes the most noise; but even if the frequency is not exactly what the

resonator was tuned for, it will still produce some destructive interference.

• Some cars, especially luxury cars where quiet operation is a key feature, have

another component in the exhaust that looks like a muffler, but is called a

resonator.

• This device works just like the resonator chamber in the muffler — the

dimensions are calculated so that the waves reflected by the resonator help

cancel out certain frequencies of sound in the exhaust.

• There are other features inside this muffler that help it reduce the sound level

in different ways.

• The body of the muffler is constructed in three layers: Two thin layers of

metal with a thicker, slightly insulated layer between them. This allows the

body of the muffler to absorb some of the pressure pulses.

• Also, the inlet and outlet pipes going into the main chamber are perforated

with holes. This allows thousands of tiny pressure pulses to bounce around in

the main chamber, canceling each other out to some extent in addition to being

absorbed by the muffler’s housing.

• Resonators are like little mufflers, and are usually the “straight through”

type. They are added at the end of the exhaust system to take care of any

noise that has made it through the muffler. The muffler quiets the noise of

the exhaust by “muffling” the sound waves created by the opening and

closing of the exhaust valves. When an exhaust valve opens, it discharges

the burned gases at high pressures into the exhaust pipe, which is at low

pressure. This type of action creates sound waves that travel through the

flowing gas, moving much faster than the gas itself (up to 1400 m.p.h.),

that the muffler must silence. It generally does this by converting the

sound wave energy into heat by passing the exhaust gas and its

accompanying wave pattern, through perforated chambers of varied

sizes. Passing into the perforations and reflectors within the chamber

forces the sound waves to dissipate their energy.

ENGINE DYNAMOMETER

Chassis dynamometer

A chassis dynamometer measures power delivered to the surface of the “drive roller”

by the drive wheels. The vehicle is often parked on the roller or rollers, which the car

then turns and the output is measured. Modern roller type chassis dyne systems use

the Salvisberg roller, which improved traction and repeatability over smooth or

knurled drive rollers. On a motorcycle, typical power loss at higher power levels,

mostly through tire flex is about 10% and gearbox chain and other power transferring

parts are another 2% to 5%. Other types of chassis dynamometers are available that

eliminate the potential wheel slippage on old style drive rollers and attach directly to

the vehicle’s hubs for direct torque measurement from the axle. Hub mounted dynos

include units made by Dynapack and Rototest. These dynes should read about 10% to

15% higher than a “rear wheel” chassis dyne. Chassis dynos can be fixed or portable.

Modern chassis dynamometers can do much more than display RPM, Horsepower,

and Torque. With modern electronics and quick reacting, low inertia dyne systems,

it’s now possible to tune to best power and the smoothest runs, in real-time. It’s also

common to, on a retail level, with a wideband 02 Sensor, graphed along with RPM, to

“tune to an air fuel ratio”. Some, like Dynojet and others can also add vehicle

diagnostic information to the dyno graph as well. This is done by gathering data

directly from the vehicle’s PCM via OBD communication. Because of frictional and

mechanical losses in the various drive train components, the measured rear wheel

brake horsepower is generally 15-20 percent less than the brake horsepower measured

at the crankshaft or flywheel on an engine dynamometer.

Other sources, after researching several different “engine” dyno software packages,

found that the engine dyno user can integrally add “frictional loss” channel factors of

+10% to +15% to the flywheel power, raising the claim that 20% to 25% or even

more power is actually lost between the crankshaft at high power outputs.