Evaluation of The Air Conditioning System

Technical Description: Air Conditioner

Air conditioning is the conditioning of air within a defined space, usually a residence or a place of business. Conditioning usually involves heating or cooling, humidifying or dehumidifying and filtering or cleaning air. If you have a central air conditioner, your system cools and dehumidifies the defined space. Following some background, this technical description provides details about three main parts of the air conditioning unit:

• Cooling Tower
• Compressor
• Chilled Water System
• Background

An air conditioner is basically a refrigerator without the insulated box. A typical air conditioner is doing exactly the same thing in exactly the same way. You can see a typical air conditioner with this diagram:

Cooling Tower

In air conditioning systems air is used to dissipate the heat from the outside coil. In some systems, the efficiency can be improved significantly by using a cooling tower. The cooling tower creates a stream of lower-temperature water. This water runs through a heat exchanger and cools the hot coils of the air conditioner unit. It costs more to buy the system initially, but the energy savings can be significant (especially in areas with low humidity) over time and the system pays for itself fairly quickly.

Cooling towers come in all shapes and sizes:

Source Author Source How stuff works

However, they all work on the same principle. A cooling tower blows air through a stream of water so that some of the water evaporates. Generally the water trickles through a thick sheet of an open plastic mesh, and air blows through the mesh at right angles to the water flow. The evaporation cools the stream of water. Because some of the water is lost to evaporation, the cooling tower constantly adds water to the system to make up the difference.

Compressor

The compressor compresses cool freon gas, causing it to become hot, high-pressure freon gas (red in the diagram). This hot gas runs through a set of coils so it can dissipate its heat, and it condenses into a liquid in the process. The freon liquid runs through an expansion value, and in the process it evaporates to become cold, low-pressure freon gas (light blue in the diagram). This cold gas runs through a set of coils that allow the gas to absorb heat and cool down the air inside the building. The compressor is the main engine of the air conditioner. It is the part that runs the entire system. The compressor is rated in BTU. A BTU is, generally, the amount of heat required to raise the temperature of one pound of water one degree F. Specifically, a BTU is 1,055 joules, but the first definition is easier to understand. One "ton", in heating and cooling terms, is 12,000 BTUs.

A typical air conditioner might be rated at 10,000 BTUs. What that means is that the air conditioner has the ability to cool 10,000 pounds of water (about 1,200 gallons) one degree in one hour. Or it could cool 5,000 pounds 2 degrees in one hour. Or 2,500 pounds 4 degrees in one hour, and so on.

Source York

Chilled Water System

In a chilled water system, the entire air conditioner lives on the roof or behind the building, and it cools water to 40 or 45 degrees F. 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 chilled water pipe if it is well-insulated. The heat exchanger lets the cold freon chill the water that runs throughout the building.

Performance Specifications

The York version of the air conditioner offers the following performance standards:

• Maximum circuit ampacity is 11.7
• Normal voltage ranges from 187 to 252
• Dimensions are 19x35x23
• Unit charge is 4 lbs. 3 oz.