Forms of air-conditioning systems commonly used in engineering-Part 1

Air-conditioning systems generally consist of air-handling equipment and air-conveying ducts, as well as air-distributing devices. According to the need, it can be composed of many different forms of systems. The forms of air-conditioning systems commonly used in engineering include primary return air-conditioning systems, variable air volume (VAV) air-conditioning systems, fan coil + fresh air air-conditioning systems, water-ring heat pump air-conditioning systems, variable refrigerant flow (VRV) air-conditioning systems, and domestic (house-type) central air-conditioning systems.

1. Primary return air-conditioning system

Primary return air-conditioning systems need to utilise a portion of the return air on most occasions during the air treatment process. In the transition season, the proportion of fresh air volume should be increased, which is conducive to energy saving; however, in summer and winter, the proportion of return air volume should be increased and the proportion of fresh air volume should be reduced, the more economically the system operates. However, in practice, in order to health requirements, can not be unlimited reduction of new air volume. Air conditioning system design, is usually taken to meet health requirements, to meet the requirements of supplemental local exhaust requirements, to maintain air-conditioned room pressure requirements of the three largest as the calculated value of the system's new air volume. In addition, for the vast majority of air-conditioning systems, when the new air volume derived from the above method is less than 10 per cent of the total air volume, it is also determined by 10 per cent.

2. Variable Air Volume (VAV) Air Conditioning Systems

The working principle of this system is that when the air-conditioning room load changes, the system end device automatically adjusts the air supply volume sent to the room to ensure that the room temperature is maintained within the design range, thus making the air-conditioning unit in the low load when the air supply volume declines, and air-conditioning unit blower speed is also reduced, to achieve energy saving purposes.

3. Fan coil + fresh air conditioning system

Fan coil + fresh air conditioning system is a major form of air-water air conditioning system, as the name implies it can be divided into two parts: one is set up according to the room fan coil unit, its role is to bear the air-conditioning room cold, hot load; two is the new air system, usually the new air through the cold, heat treatment, in order to meet the requirements of indoor sanitation.

1) Forms of fan coil units

From the form of air flow points, there are fans located in the coil downwind side, the air is first processed by the coil, the fan sent into the air-conditioning room of the inhalation type; fan in the coil on the wind side, the fan will be the indoor air pumping, pressure sent to the coil for cold, heat exchange, and then sent to the air-conditioning room of the pressure out of the type. Inhalation type is characterised by: coil air intake uniformity, cold, thermal efficiency is relatively high, but the water temperature of the coil for hot water can not be too high; and pressure out of the most widely used form of structure.

According to the installation form, there are vertical surface mounted, horizontal surface mounted, vertical concealed, horizontal concealed, ceiling-mounted (also known as recessed).

By Sammi