【文章內(nèi)容簡介】 ace. The units are made small enough to fit into a standard window frame. You close the window down on the unit, plug the unit in and turn it on to get cool air. If you take the cover off of an unplugged window unit, you will find that it contains: A pressor An expansion valve A hot coil (on the outside) A chilled coil (on the inside) A control unit The fans blow air over the coils to improve their ability to dissipate heat (to the outside air) and cold (to the room being cooled). BTU and EER Most air conditioners have their capacity rated in British thermal units (BTU). Generally speaking, a BTU is the amount of heat required to raise the temperature of one pound ( kg) of water 1 degree Fahrenheit ( degrees Celsius). Specifically, 1 BTU equals 1,055 joules. In heating and cooling terms, 1 ton equals 12,000 BTU. A typical window air conditioner might be rated at 10,000 BTU. For parison, a typical 2,000squarefoot ( m2) house might have a 5ton (60,000BTU) air conditioning system, implying that you might need perhaps 30 BTU per square foot. (Keep in mind that these are rough estimates. To size an air conditioner for your specific needs, contact an HVAC contractor.) The energy efficiency rating (EER) of an air conditioner is its BTU rating over its wattage. For example, if a 10,000BTU air conditioner consumes 1,200 watts, its EER is (10,000 BTU/1,200 watts). Obviously, you would like the EER to be as high as possible, but normally a higher EER is acpanied by a higher price. Is the higher EER is worth it? Let39。s say that you have a choice between two 10,000BTU units. One has an EER of and consumes 1,200 watts, and the other has an EER of 10 and consumes 1,000 watts. Let39。s also say that the price difference is $100. To understand what the payback period is on the more expensive unit, you need to know: how many hours per year you will be operating the unit much a kilowatthour (kWh) costs in your area Let39。s say that you plan to use the air conditioner in the summer (four months a year) and it will be operating about six hours a day. Let39。s also imagine that the cost in your area is $is 200 watts, which means that every five hours the less expensive unit will consume 1 additional kWh (and therefore $ more) than the more expensive unit. Assuming that there are 30 days in a month, you find that during the summer you are operating the air conditioner: Since the more expensive unit costs $100 more that means that it will take about seven years for the more expensive unit to break even. See this page for a great explanation of seasonal energy efficiency rating (SEER). Splitsystem Units A splitsystem air conditioner splits the hot side from the cold side of the system。 The cold side, consisting of the expansion valve and the cold coil, is generally placed into a furnace or some other air handler. The air handler blows air through ducts. The hot side known as the condensing unit, lives outside the building. The unit consists of a long, spiral coil shaped like a cylinder. Inside the coil is a fan, to blow air through the coil, along with a weatherresistant pressor and some control logic. This approach has evolved over the years because it is lowcost, and also because it normally results in reduced noise inside the house (at the expense of increased noise outside the house). Besides the fact that the hot and cold sides are split apart and the capacity is higher (making the coils and pressor larger), there is no difference between a splitsystem and a window air conditioner. In warehouses, businesses, malls, large department stores, etc., the condensing unit normally lives on the roof and can be quite massive. Alternatively, there may be many smaller units on the roof, each attached inside to a small air handler that cools a specific zone in the building. Let39。s take a look now at a chilledwater air conditioner. Chilledwater System In larger buildings and particularly in multistory buildings, the splitsystem approach begins to run into problems. Either running the pipe between the condenser and the air handler exceeds distance limitations (runs that are too long start to cause lubrication difficulties in the pressor), or the amount of duct work and the length of ducts bee unmanageable. At this point, it is time to think about a chilledwater system. In a chilledwater system, the entire air conditioner lives on the roof or behind the building. It cools water to between 40 and 45 F ( and C). This chilled water is then piped throughout the building and connected to air handlers as needed. There is no practical limit to the length of a chilledwater pipe if the system can be got well insulated. Whenever you walk behind a building and find a unit that has large quantities of water running through a plastic mesh, you will know you have found a cooling tower! In many office plexes and college campuses, cooling towers and air conditioning equipment are centralized, and chilled water is routed to all of the buildings through miles of underground pipes. Based on dynamic load track central airconditioning system entire closed loop energy conservation technology research. 1. introductions The energy conservation may say is the building character automatic control system starting point and the home to return to. It is well known, in the intelligent construction, HVAC (heating, ventilates and air conditioning) the system consumes to have to occupy the building consumption total energy enormous partial proportions, approximately about 50% ~60%. Specially cold: East the unit, the cooling tower, the circulating water pump and the air conditioning unit, the new atmosphere unit, all are consumes energy the big household. Therefore really has essential develops one effective airconditioning system energy