HVAC: Heating, Ventilation & Air-Conditioning

This article describes the arrangement of compressors in the package air conditioners with multiple compressors. It also describes the capacity control system in these units.

There are four important parts of a refrigerator: compressor, condenser, expansion valve and evaporator. Freon gas passes through all these parts continuously in the form of a cycle and undergoes various phase and temperature and pressure transformations. Freon acts as the media for transfer of heat.

Central air conditioning plants are used for applications like big hotels, large buildings having multiple floors, hospitals, etc, where very high cooling loads are required. The article describes various possible arrangements of central air conditioning plants.

Air conditioning is the process of maintaining comfortable conditions inside a closed space. It controls temperature, humidity, air flow rate and the cleanliness of air inside a room.

In many cases especially in places of heavy rainfall, the dehumidification carried out by air-conditioners is not sufficient because the moisture content of the air is extremely high. In such cases portable dehumidifiers are very useful and convenient to use.

The HVAC system selected haphazardly for your home or office can turn out to be insufficient or highly expensive. For achieving comfortable conditions at optimum costs, HVAC design for your home or office is important.

The refrigerating compressor is considered to be the heart of refrigeration and air-conditioning systems. The compressor compresses the refrigerant and consumes most of the power of refrigerating and air-conditioning units.

Heat is generated inside the room from various sources. Some of these include heat gained by the walls, heat entering from the windows, heat generated by the people, electrical equipments etc.

The refrigerant undergoes various changes throughout the vapor compression cycle and it is in the evaporator where it actually produces the cooling effect. The evaporator is usually a closed insulated space where the refrigerant absorbs heat from the substance or food to be cooled.

A number of software programs have come on the market that make complex HVAC design and heat load calculations very simple. Here one such product named AutoCAD HVAC Design software is described.

Refrigerants are the life blood of the vapor compression system. The refrigerant flows continuously through the vapor compression cycle, absorbing the heat in the evaporator and releasing it in the condenser. It undergoes various phase changes while flowing though the cycle.

The human body is like a machine that consumes fuel and produces power and heat. When the body consumes food, which contains lots of calories, it gets converted partially into energy and partially into heat. To attain body comfort, the excess heat generated inside the body should be removed.

The human body feels comfortable at certain values of temperature, relative humidity and velocity of air inside a room. These are called comfort conditions or comfort zone. They depend on a number of factors, which the HVAC designers should be aware of.

In throttling devices the pressure of the refrigerant drops down suddenly and due to this its temperature also reduces drastically. This article describes various types of throttling devices being used for refrigerator and air-conditioning systems.