21st Century High Efficiency Air Conditioning Systems with Flexible Zoning
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21st Century High Efficiency Air Conditioning Systems with Flexible Zoning |
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UNDERSTANDING THERMAL ENERGY Warm-blooded creatures (humans) don't need to be heated from an external source. We have a built-in heating system. Our comfort is dependent on our ability to control how quickly we lose heat. If your body is making heat faster than you can get rid of, you will feel hot. If you are losing heat faster than the body can produce it, you will feel cold. The amount of heat that the body produces is different from one person to another and changes constantly within each individual. For instance you are more likely to need to conserve heat when you are hungry or sleeping because your internal furnace is not producing as much energy. Conversely, if you are active and your furnace is "fueled up", you will likely need to increase the rate of heat transfer away from the body. For a person to feel perfectly comfortable the air temperature around them would have to be constantly changing, and would be different surrounding each person. For the best comfort possible, you do not want to heat or cool the body but to control how fast the body loses heat. There are three methods of transferring thermal energy or heat: conduction, radiant and convection. In all cases energy is being transferred from the object with the higher temperature to the colder one. Cold is simply the absence of heat. Heat or thermal energy is constantly seeking to move to any object cooler than it is. In the heating and air-conditioning world we measure thermal energy in BTU's. A BTU is the amount of thermal energy required to raise one pound of water one degree in one hour. Conduction: is the direct transfer of thermal energy from one solid object to another - by contact. For example, when you touch something that is cold or hot, or when you get into water, thermal energy is being conducted. The denser or heavier the object the faster the heat will transfer. Also, the heat will transfer up or away from gravitational pull at a much higher rate than down. Normally conduction is the most efficient or positive method of heat transfer. For instance, nothing will cool or heat a person faster than emersion in a cold or hot liquid. We have all seen the advertisement of someone pressing a cold can of soda against their forehead. Unfortunately, short of enclosing ourselves in a suit of water with a portable heating/cooling system attached, conduction is not a practical means for heating or cooling our homes. Radiant: is also a thermal transfer between two objects. However, Radiant heat transfer occurs not through direct contact but through low frequency energy waves flowing from the object of higher temperature to one of lower temperature. The remarkable thing about this process is that because air is of such low density, the air between the objects does not change temperature significantly. Radiant heat is an extremely comfortable, efficient and environmentally friendly way to heat a home. It is however, much less effective as a means to cool a home. While radiant cooling systems do exist the biggest problem comes from condensation. As objects/surfaces cool they pull moisture from the warmer air around them and condensation occurs. The result is likely to be slippery floors and/or moldy walls and ceilings. Even in extremely low humidity environments where the condensation risks can be minimized, the most efficient way to implement a radiant cooling system is to install it in a ceiling which necessitates a dedicated infrastructure separate from even a radiant heating system. Convection: is the transfer of thermal energy from one object to another by cooling/heating air with one object and then transferring the air to another object to cool/heat it. We know that just moving air past us will carry the heat away and make us feel cooler. Sitting in front of a fan can bring some relief from a hot day. However, when our surroundings are as warm as we are, the cooling effect of moving air is minimized. The air has to move faster and faster to bring any relief. Gale force winds might be enough to keep us cool but they bring a new set of problems. The most effective air conditioning system is a combination of cool surfaces and a gentle movement of air. Contrast the limited cooling effect of wind in a mall parking lot from one blowing off of a lake. Because the lake water is cooler than the mall surroundings that air is able to absorb more heat as it passes by us. An air conditioning system that relies on cold air but leaves the objects around you warm will not be as efficient or as comfortable as it could be. That is one of the limitations of traditional forced-air systems, where heating and cooling are combined. Typically, forced air systems locate registers in or near the floor. In this case the walls, ceiling and other objects in the room will not be cooled (cold air is heavier and doesn't rise). Hence they will continue radiating heat toward you. The Arcticool system design overcomes the limitations of other convection based systems to provide you with the highest value air conditioning system available - comfortable, efficient, zone-able, quiet, easy to install and affordable.
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