Air conditioning Although the word condition means something like set a condition, the term air conditioning, reserved only to the process of maintaining a closed to a stable temperature and pleasant, local users by cooling, whereas if the same effect is achieved by heating, always refers to it as heat. Production of cold air The cooling capacity of air conditioning systems is measured in different units according to the system of units used in the country, so we can be: 1 .- tons of refrigeration, where a ton of refrigeration is defined as the amount of heat needed to extract, to lose one degree Fahrenheit at one ton (2000 lb) of pure water. 2.-frig, where a BTU is the amount of heat that we have to remove 1 kg of water at 15 degrees Celsius to reduce this temperature by 1 degree celcius. 3 .- BTU, where a BTU is the amount of heat to extract a pound of water to lower its temperature one degree Fahrenheit. From the construction point of view, air conditioning machines can be classified into:
Wall Machines Directly-cooled machines, which is then brought cold and hot ducts returned to the unit that is placed on the outside. Machines are divided into two units, one outside and pump the resulting liquid refrigerant known as an indoor console where the refrigerant evaporates and heat is exchanged with the ambient air. External machines, water chillers, this water is then pumped through pipes and used to cool the air in heat exchangers locally distributed throughout the building. Each of these machines are air conditioned its scope depending on the volume and type of building to serve, so for example, wall machines are reserved for local cooling of one, if in addition it has, a wall to communicate abroad, while the machines of cases 2 and 3 are used to condition the air throughout a home or an entire floor of a building a few floors up. The water chilling systems are reserved for high rise buildings where the relatively small diameter of water pipes, as well as its ease of pumping, the project becomes more viable. A general outline of an air conditioning system air cooler directly, is shown below. scheme
In the drawing can be seen the same basic parts of a liquefaction cooling system, compressor, condenser, evaporator and expansion valve. The distinguishing feature of this system against a conventional refrigeration is that in this, the final temperatures required are much higher (with a minimum of about 10 degrees Celsius), while in the conventional refrigerator, may be in the order of tens degrees Celsius below zero. Another significant difference is that in this case, large amounts of cool air, making circular forced through the evaporator with the use of a ventilator, the air contains dust and other suspended solids, which tend to stick to the blades cold and wet evaporator, forming an insulating layer and obstructing the passage of air through them, so it is necessary to use filters that will be renewed from time to time. Additionally, these systems unlike in the conventional refrigerator, must constantly exchange, part of the local indoor air with outdoor air to maintain a breathable atmosphere and healthy within the premises. A typical air conditioning system console can be seen in the picture below. drawing
In the picture we have left out the parts belonging to the production of compressed refrigerant (compressor and pipes) and the console displayed only the heat exchanger. These consoles are usually equipped with two axial fans, one to force outside air through the condenser to liquefy the compressed refrigerant, and another to recirculate indoor air through the evaporator, and share a little part of indoor air with air Fresh from the outside. In all cases, the front surface of the evaporator, or at the entrance to the chamber where this is placed a special filter capable of retaining solid particles suspended in the incoming air, without producing appreciable resistance to the passage of air. In some cases, the share of the capacitor is coupled with the compressor in one unit, and the refrigerant liquid reaches the console. In this case, the console is smaller and only has the supply fan, evaporator and filter system. It has the disadvantage that the exchange of indoor air with fresh air fails, this exchange is not important when the premises are large and few people use it, where the opening and closing doors, lost them and the tightness of windows, and the natural exchange of vent chimneys and domestic devices is sufficient. For larger buildings that use the water cooling method can be used absorption refrigeration systems with a local console, using cold water as a coolant. Ventilation systems of these large buildings are separate systems. To maintain a stable temperature in all air conditioning systems, they go to thermostats, these thermostats can control starting and stopping of the compressors, or drive electric or hydraulic systems that open and close air dampers cold, or cold water, as appropriate.
Local conditions to cool. For an air conditioning system energy efficient, premises must meet certain requirements for air tightness and thermal insulation. Local bit tight or large heat inputs walls, ceilings and floors are not suitable, and its energy consumption would be very high. It is common practice in hot weather, dress exterior walls on the inside, with a heat insulating material of about 19 mm thick and then cover it with drywall, paper, plywood and the like. Also, false ceilings or ceiling are covered with layers of about 100 mm insulating fiberglass base or similar. For this purpose, white roofs are the most suitable. Amount of cooling needed. The required cooling capacity chiller installation for a particular local set based on the square footage of exterior wall. These requirements are also influenced by several factors, the most important are: 1 .- glass wall area (the more glass more losses). 2 .- Internal heat generation equipment or facilities. 3 .- Number of people at a time on the premises. 4 .- Type of roof and if the outside. 5 .- Average annual outdoor temperature. 6 .- Geographical focus. 7 .- Building materials, whether or not insulation. 8 .- Color exterior walls and ceilings. 9 .- Other
In practice it is accepted that the range of BTU per square foot of wall between 100 and 150 depending on additional influential factors listed above. Can be reduced kilowatts of power a refrigerator to BTU, multiplying by 0.86. Cold air distribution After creating the device to prepare the cold air, it is necessary sharing among the different local service object, evenly, to ensure that all of them, there is the same temperature. This distribution when it comes to multiple locations is almost universally through ducts. The draft pipes and parts thereof, for the proper distribution of cold air at the locations, can be anything from a simple opening of discharge and a return on the machine as in the case of the wall, to complex systems equipped of a network of pipes of different flow sections interconnected grids with multiple exit and return, check gate systems and control flow in case of fire etc. For proper operation of an air conditioning system, regardless of its complexity, it is very important not only to distribute the cold air to a greater or lesser extent to each location on your terms, but also, to achieve an adequate return. An output window in a local cold air will be non-functional if the cold air discharge is not clear-cut chances of returning to the refrigerator. Temperature Regulation
For an air conditioning system works properly it will be necessary as already indicated, the use of thermostats. These thermostats can vary substantially from one facility to another depending on the complexity of the system. For a simple system like a house, the thermostat is reduced to an electrical control switches the compressor and air recirculation fans, but in the case of commercial buildings where they may be many people at the same time, more common is to use twin bulb thermostat included in the same body and driven by the same stick. One of these thermostats pear served on and off the compressor, and the other for the recirculation fans. Both are out of phase value somewhat in temperature so that always the thermostat controls the compressor operates at a higher temperature than the other, thus the compressor will turn off and turn on and off to maintain the temperature of the room, but recirculation fans always remain lit to ensure adequate exchange of air with using non. If you want to hand off the entire system, you can lever up the temperature above the thermostat calibration value of the recirculation fans.