air conditioning

In central units of air heating systems the supply air flow must meet the actual heating demand. Most of central units for air heating systems have only one fan , which is designed for the maximum air flow at the maximum heating capacity . Fan motors are designed for variable - voltage-drive to enable a reduction of air flow to the necessary value at different heating demands. However, the electrical efficiency is decreasing strongly. The supply air fan is working mostly under part - load conditions . Therefore the control strategy used now is very ineffective .

VAV - air conditioning system makes it possible to control indoor conditions even when the heat loads are changing. But this is possible only when each part of the system works as it is intended to work. When the air flow varies in a large range, it can cause situations, where pressure loss of some flow dampers are out of their operating range. This is possible especially whenthe system is large and the velocities are high. This means that the air flow is not correct. Also increasing noise levels may appear.

This paper describes a simulation program which was developed for the modelling of air-conditioning systems and conditioned spaces in industrial buildings. The program can be used for a design of systems for new buildings and for analysis of existing ones. By viewing the building as a dynamic entity, it is possible to investigate how thermal capacity of the building elements acts on both the conditioned space and the performance of the air-conditioning system. The program simulates three important aspects of a building.

The air flow within a room, the interchange of air between rooms and the interchange of air between a building and the exterior are topics which until today have received little attention by researchers.

The third of six booklets designed as a guide for energy management in hospitals. It focuses on the requirements of the various zones of a hospital, and how they can be met in an energy efficient way, by means of heating, ventilating, air conditioning systems.