A.What is air conditioner
Air conditioning (often referred to as A/C or AC) is the process of altering the properties of air (primarily temperature and humidity) to more comfortable conditions, typically with the aim of distributing the conditioned air to an occupied space such as a building or a vehicle to improve thermal comfort and indoor air quality. In common use, an air conditioner is a device that lowers the air temperature. Thecooling is typically achieved through a refrigeration cycle, but sometimes evaporation or free cooling is used. Air conditioning systems can also be made based on desiccants.[1]
In the most general sense, air conditioning can refer to any form of technology that modifies the condition of air (heating, cooling, (de-)humidification, cleaning, ventilation, or air movement). However, in construction, such a complete system of heating, ventilation, and air conditioning is referred to as heating, ventilation, and air conditioning (HVAC -as opposed to AC).[2]

B. Heater
1. Principles of Air Conditioning
BASIC PRINCIPLES OF AIR CONDITIONING
You don’t have to be an air-conditioning expert to use Spot Coolers, but understanding the basics of air conditioning will help you understand how Spot Coolerswork.
This section highlights some of the basic principles of air conditioning for those who would benefit from additional knowledge in this area.
PRINCIPLES OF COOLING
Heat Transfer
Heat is a form of energy. Every object on earth has some heat energy. The less heat an object has, the colder we say it is. Cooling is the process of transferring heat from one object to another. When an air-conditioning system cools, it is actually removing heat and transferring it somewhere else. This can be demonstrated by turning on a Spot Cooler and placing one hand in front of the cold air nozzle and the other over the warm air exhaust. You will feel the action of the transfer of heat.
SENSIBLE AND LATENT HEAT
There are two forms of heat energy: sensible heat and latent heat.
Sensible heat is the form of heat energy which is most commonly understood because it is sensed by touch or measured directly with a thermometer. When weather reporters say it will be 90 degrees, they are referring to sensible heat.
Latent heat cannot be sensed by touch or measured with a thermometer. Latent heat causes an object to change its properties. For example, when enough latent heat is removed from water vapor (steam or humidity), it condenses into water (liquid).
If enough latent heat is removed from water (liquid), it will eventually freeze. This process is reversed when latent heat is added.
CHANGE OF STATE
An object that changes from a solid to a liquid or liquid to vapor is referred to as a change of state. When an object changes state, it transfers heat rapidly.
HUMIDITY
Moisture in the air is called humidity. The ability of air to hold moisture directly relates to its temperature.
The warmer air is, the more moisture it is capable of holding. Relative humidity is the percentage of moisture in the air compared to the amount of moisture it can hold. A moisture content of 70°F air with 50% relative humidity is lower than 80°F air with 50% relative humidity.
When the humidity is low, sweat evaporates from your body more quickly. This allows you to cool off faster. High humidity conditions do not allow sweat to evaporate as well because the air is at its maximum capacity.
Humidity is also a form of latent heat. When air contains more humidity, it has more latent heat.
REFRIGERANT
Refrigerants are substances used by air conditioners to transfer heat and create a cooling effect. Air-conditioning systems use specially formulated refrigerants designed to change state at specific temperatures providing optimum cooling.
Portables use a refrigerant called R-22 or HCFC-22. HCFC stands for hydrochlorofluorocarbon.This is currently the most common refrigerant used by air-conditioning systems.
REFRIGERANT PHASE-OUT
Many of the current forms of refrigerants used today are being phased out based on concern for depletion of the ozone layer. Portables use R-22, which has been deemed acceptable for use by the EPA until the year 2010. By that time, an ozone-friendly refrigerant that can be easily substituted for R-22 will be readily available.
AIR-CONDITIONING SYSTEMS
The system by which air conditioners provide cooling is called the Refrigerant Cycle. This system has four major components common to all air-conditioning systems (see figure below). These components and their basic functions are listed below.
1. Compressor
Refrigerant is drawn from the evaporator and pumped to the condenser by the compressor. The compressor also pressurizes the refrigerant vapor so that it will change state (condense) readily.

2. Condenser
The high-pressure refrigerant vapor releases heat through the condenser coils as it condenses into liquid refrigerant. making it easier to vaporize.
3. Metering Device
(capillary tube, txv valve) The metering device restricts the flow of liquid refrigerant from the condenser to the evaporator. As refrigerant passes through the metering device, its pressure decreases.
4. Evaporator
The low-pressure liquid refrigerant absorbs heat as it vaporizes in the evaporator coils.
The process described above is the Refrigerant System or Refrigerant Cycle. It is the system on which virtually all modern Air-Conditioning and refrigeration is based.

2.Types of Air Conditioners
Operating Principle
The basic types of air conditioners are room air conditioners, split-system central air conditioners, and packaged central air conditioners.
Room Air Conditioners
Room air conditioners cool rooms rather than the entire home. If they provide cooling only where they're needed, room air conditioners are less expensive to operate than central units, even though their efficiency is generally lower than that of central air conditioners.
Smaller room air conditioners (i.e., those drawing less than 7.5 amps of electricity) can be plugged into any 15- or 20-amp, 115-volt household circuit that is not shared with any other major appliances. Larger room air conditioners (i.e., those drawing more than 7.5 amps) need their own dedicated 115-volt circuit. The largest models require a dedicated 230-volt circuit.

Source: http://www.energystar.gov Central Air Conditioners
Central air conditioners circulate cool air through a system of supply and return ducts. Supply ducts and registers (i.e., openings in the walls, floors, or ceilings covered by grills) carry cooled air from the air conditioner to the home. This cooled air becomes warmer as it circulates through the home; then it flows back to the central air conditioner through return ducts and registers.
A central air conditioner is either a split-system unit or a packaged unit.
Split System
In a split-system central air conditioner the main components include: * an outdoor metal cabinet that contains the condenser and compressor; * an indoor cabinet that contains the evaporator. * In many split-system air conditioners, the indoor cabinet also contains a furnace or the indoor part of a heat pump. The air conditioner's evaporator coil is installed in the cabinet or main supply duct of this furnace or heat pump.
If your home already has a furnace but no air conditioner, a split-system is the most economical central air conditioner to install.

Illustration of a split air conditioning system Packaged Units
The packaged central air conditioner is usually located outdoors and consists of one cabinet that contains the evaporator, condenser, and compressor. The cabinet is usually placed on a roof or on a concrete slab next to the house's foundation. The packaged air conditioner is connected to the indoor air supply and return ducts through the home's exterior wall or roof.
Since these air conditioners often include electric heating coils or a natural gas furnace, this combination of air conditioner and central heater eliminates the need for a separate furnace indoors. This type of air conditioner is used to cool and heat homes as well as small commercial buildings

C. Cooler
1. Basic Teory of cooling
Basic Cooling System Theory
The internal combustion engine is a very inefficient way to power a car. Most of the energy of the fuel is wasted creating heat. This heat, if not removed, will quickly cause the engine to get so hot that the metal parts will melt. The cooling system is there to remove that excess heat. As engine efficiency has improved over the years, cooling systems have gotten smaller and smaller. In the fifties, the average cooling system contained 24 or more liters of coolant, now, the average is somewhere around 8. My Firefly holds less than 4.
The way the whole thing works is really quite simple. The heat is transferred from the hot engine parts to the coolant, which flows to the radiator where the heat gets transferred to the air that is flowing through the fins. Then the coolant flows back into the engine where it picks up more heat and so on . . .
The main problem that occurs is problems with the flow. Flow problems are pretty simple to figure out, usually there is an obstruction such as a stuck thermostat, water pump not turning, collapsed radiator hose, plugged radiator, air bubble in the engine, etc.
Cooling System Components:
Cooling System Components TERM: | DEFINITION: | Radiator: | The radiator is the key to the entire cooling system, it is the part that actually transfers the excess heat produced in the engine to the outside air. It is made up of several rows of small tubes connecting two containers which hold the coolant. Small fins are placed around the tubes to direct air around the outside of the tubes and to help the heat transfer from the tubes to the outside air. | Radiator hoses: | The radiator hoses don't do much except transport the coolant into and out of the radiator. The normal flow is from the lower hose to the water pump, through the cooling passages in the engine, and back through the thermostat to the upper hose and then to the radiator. | Water pump: | The water pump furnishes the force that moves the coolant around the system. (Duh) Most common problem is a leak that will appear at the small hole that you can see near the shaft if you look closely. This leak isn't a problem if you make sure that you top up the system on a regular basis. | Thermostat: | The thermostat blocks off the main path for the hot coolant to return to the radiator, causing a large portion of it to be directed through the heater core and back to the engine until it reaches normal operating temperature and the thermostat opens. At this point coolant starts to flow to the radiator through the upper radiator hose. This function makes your heater produce heat faster, as well as helps the engine warm up quicker. | Heater hoses: | Transport coolant to and from the heater core. (duh) Look for leaks at the hose clamps where they connect to the heater core and the engine. | Heater core: | A mini-radiator that is used to heat the air inside the car. The hot coolant flows through the tubes and air is directed through the fins, absorbing the heat and then being directed to the cab or to the windshield defrost vents. When your heater core starts to get plugged up, you will gradually get less and less heat from your heater. A flush might help, but it could also trigger a leak... | Coolant: | In the olden days, cars used plain water for coolant, and it worked fairly well, except when it froze. Modern cars run at a higher temperature and use much smaller cooling systems. The vast majority of cars use a 50-50 mix of ethylene glycol and water for coolant, which also gives anti-freeze and anti-corrosion protection. In extreme cold climates, a mixture of up to 75% antifreeze to 25% water is used. Don't try to run your car on pure anti-freeze! The engine will overheat. If you use distilled water for the mix, you'll have significantly less corrosion. | Radiator cap: | The cap just keeps the coolant from sloshing out of the radiator and it maintains a positive pressure in the cooling system. Since the boiling temperature of the coolant is dependent on the pressure, this feature is necessary for proper functioning of the system. | Thermostat: | The thermostat is probably the cheapest part of the cooling system. Mainly for this reason, every customer that comes in the door with an overheating problem is required to say, "It's probably the thermostat." This is a law of nature. The thermostat has one job, that is to block the main coolant return passage to the radiator until the engine heats up to operating temperature. Then the thermostat opens and the coolant circulates. If the top radiator hose gets hot, and coolant flows freely into the top of the radiator, then the thermostat is opening. Still, a new one can't hurt, and most of them are fairly easy to replace, so why not? Be warned though, I've seen brand new thermostats that were defective. | Bypass hose: | The bypass hose allows a small portion of the coolant to circulate when the thermostat is closed, get it? Bypassing the thermostat. Some engines don't have a bypass hose, but rather a bypass passage that is part of the engine cooling jacket. Not much to go wrong, unless the hose develops a leak, which they do with depressing regularity. |
2. Types of Cooling System
Air conditioning, or cooling, is more complicated than heating. Instead of using energy to create heat, air conditioners use energy to take heat away. The most common air conditioning system uses a compressor cycle (similar to the one used by your refrigerator) to transfer heat from your house to the outdoors.
Picture your house as a refrigerator. There is a compressor on the outside filled with a special fluid called a refrigerant. This fluid can change back and forth between liquid and gas. As it changes, it absorbs or releases heat, so it is used to “carry” heat from one place to another, such as from the inside of the refrigerator to the outside. Simple, right?
Well, no. And the process gets quite a bit more complicated with all the controls and valves involved. But its effect is remarkable. An air conditioner takes heat from a cooler place and dumps it in a warmer place, seemingly working against the laws of physics. What drives the process, of course, is electricity — quite a lot of it, in fact.
Types of Cooling Systems
Central Air Conditioners and Heat Pumps
Central air conditioners and heat pumps are designed to cool the entire house. In each system, a large compressor unit located outside drives the process; an indoor coil filled with refrigerant cools air that is then distributed throughout the house via ducts. Heat pumps are like central air conditioners, except that the cycle can be reversed and used for heating during the winter months. (Heat pumps are described in more detail in the heating section.) With a central air conditioner, the same duct system is used with a furnace for forced warm-air heating. In fact, the central air conditioner typically uses the furnace fan to distribute air to the ducts.
Central air conditioners and air-source heat pumps operating in the cooling mode have been rated according to their seasonal energy efficiency ratio (SEER) since 1992. SEER is the seasonal cooling output in Btu divided by the seasonal energy input in watt-hours for an “average” U.S. climate. Before 1992, different metrics were used, but the performance of many older central air conditioners was equivalent to SEER ratings of only 6 or 7. The average central air conditioner sold in 1988 had a SEER-equivalent of about 9; by 2002 it had risen to 11.1.The national efficiency standard for central air conditioners and air source heat pumps now requires a minimum SEER of 13 (since 2006), and to qualify for ENERGY STAR requires a SEER of 14.5 or higher. Central air conditioners also come with an energy efficiency ratio (EER) rating, which indicates performance at higher temperatures. ENERGY STAR-qualified models must meet an EER requirement of 12.

Air conditioners and heat pumps use the refrigerant cycle to transfer heat between an inside unit and an outside uint. Heat pumps differ from air conditioners only in the special valve that allows the cycle to reverse, providing either warm or cool air to the inside.
New efficiency standards for central air conditioners take effect in 2015. As with furnaces, the new standards will differ by region, with greater stringency in the South and Southwest than in the North. New central air conditioners sold for installation in the South and Southwest must meet a minimum 14 SEER; for units installed in the North, the 13 SEER minimum remains unchanged. Air-source heat pumps must meet the 14 SEER minimum regardless of where they are installed. In addition, central air conditioners installed in the hot, dry Southwest must meet a minimum 12.2 EER (or 11.7 EER for larger models).
In contrast, cooling performance of ground source heat pumps is measured by the steady state EER instead of a seasonal measure. The ENERGY STAR program’s minimum requirements for ground-source heat pumps are 21.1 EER for open-loop systems, 17.1 EER for closed-loop systems, and 16 EER for direct expansion (DX) units.
Room Air Conditioners
Room air conditioners are available for mounting in windows or through walls, but in each case they work the same way, with the compressor located outside. Room air conditioners are sized to cool just one room, so a number of them may be required for a whole house. Individual units cost less to buy than central systems.
Room air conditioners are rated only by the EER, which is cooling output divided by power consumption. The higher the EER, the more efficient the air conditioner. Revised federal minimum efficiency standards for room air conditioners adopted in 2011 will take effect in June 2014; revised ENERGY STAR requirements will take effect in October 2013. Table 5.2 lists requirements for units with louvered sides—the most common type.
Evaporative Coolers
Evaporative coolers, sometimes called swamp coolers, are less common than vapor compression (refrigerant) air conditioners, but they are a practical alternative in very dry areas, such as the Southwest. They work by pulling fresh outside air through moist pads where the air is cooled by evaporation. The cooler air is then circulated through a house. This process is very similar to the experience of feeling cold when you get out of a swimming pool in the breeze. An evaporative cooler can lower the temperature of outside air by as much as 30 degrees.
They can save as much as 75% on cooling costs during the summer because the only mechanical component that uses electricity is the fan. Plus, because the technology is simpler, it can also cost much less to purchase than a central air conditioner — often about half.
A direct evaporative cooler adds moisture to a house, which could be considered a benefit in very dry climates. An indirect evaporative cooler is a little different in that the evaporation of water takes place on one side of a heat exchanger. House air is forced across the other side of the heat exchanger where it cools off but does not pick up moisture. Both types begin to lose their effectiveness with increasing humidity, because humid air is less able to carry additional moisture.
For evaporative coolers to do their job, they must be the right size. The cooling capacity of an evaporative cooler is measured not in the amount of heat it can remove (Btu), but in the fan pressure required to circulate the cool air throughout the house, in cubic feet per minute (cfm). A good rule is to figure the cubic square footage of your house and divide by 2. For example, a 1,500-square-foot house with 8-foot-high ceilings would require a 6,000 cfm cooler.
Ductless Mini-Split Air Conditioners
Mini-split systems, very popular in other countries, can be an attractive retrofit option for room additions and for houses without ductwork, such as those using hydronic heat (see the heating section). Like conventional central air conditioners, mini-splits use an outside compressor/condenser and indoor air handling units. The difference is that each room or zone to be cooled has its own air handler. Each indoor unit is connected to the outdoor unit via a conduit carrying the power and refrigerant lines. Indoor units are typically mounted on the wall or ceiling.
The major advantage of a ductless mini-split is its flexibility in cooling individual rooms or zones. By providing dedicated units to each space, it is easier to meet the varying comfort needs of different rooms.
By avoiding the use of ductwork, ductless mini-splits also avoid energy losses associated with central forced-air systems.
The primary disadvantage of mini-splits is cost. They cost much more than a typical central air conditioner of the same size, where ductwork is already in place. But, when considering the cost and energy losses associated with installing new ductwork for a central air conditioner, buying a ductless mini-split may not be such a bad deal, especially considering the long-term energy savings. Talk with your contractor about what option would be most cost-effective for you.
State of the Art Cooling
Night Breeze is a new home climate control technology designed to save energy in hot, dry climates. It is essentially a powered whole-house fan, air conditioner, and indirect water heater integrated under one control system. In the summer, the system draws in as much cool outdoor air as possible to meet cooling needs — the air conditioner only kicks on if absolutely necessary. In the winter, a water-to-air heat exchanger extending from the water heater supplies warm air to the system.
Contact: Davis Energy Group(link is external)
Also appropriate for dry climates, the Coolerado Cooler is an evaporative cooling technology that is 100% indirect. It can offer four to six tons of cooling with an energy consumption of 1,200 watts. Its energy efficiency ratio (EER) is 40 or higher, making it two to three times as efficient as the best conventional air conditioners.
Contact: Coolerado, LLC(link is external)
Thermal Energy Storage is a technology that is best for simply shifting energy use from peak to off-peak hours. It works by storing energy in ice — at night, electricity is used to freeze water, and during the day, the ice can cool air that is circulated throughout the house. Most cost-effective for people who live in climates that cool off at night and pay more for peak electricity use (e.g., in California), this technology is now available for residential use.