Water flow control for optimal operation of air to water heat exchanger

Abstract

Chilled beam systems are considered to be energy efficient and have the ability to provide sensible cooling in a given space. Active chilled beam systems (ACB) will be the primary focus over the passive system due to the higher cooling efficiency. ACB consists of chilled water pipes and an integral air supply unit. This is to create force induction of air in the room and the reconditioned air will be cooled again upon mixing with the primary air. Consideration of the flow and temperature of the chilled water has to be taken into account so as to prevent condensation from occurring.

Focusing on the water side ACB system, to achieve a certain desired temperature in the room and prevent condensation from occurring, the flow of water in the chilled pipe has to be regulated. This is achieved by controlling the modulating valve and pump. Thus, by understanding the valve and pump characteristics and identifying the open loop process of the equipments will enable us to create a closed loop discrete PID controller which will allow the user to control and set the flow of water in the chilled pipes. Computational, simulation and interfacing of the system processes and hardware will be aided by the use of Labview and Matlab software.

The presence of the PID controller and filter in the system results in a smooth, non-overshoot and fast response output. It does not only respond quickly to the change in flow set point however it eliminates unnecessary oscillations in the output response curve. Thorough study on the output response curve of the equipment not only exhibits the behavior of equipment given any conditions but allows further tuning and improvising of system.