Optimization of cooling coil performance during operation stages for improved humidity control

In hot and humid climates, indoor humidity levels are usually high and this is a matter of concern from Thermal Comfort and IAQ perspectives. This phenomenon can be attributed to the inadequate dehumidifying performance of the cooling coil. Amongst other factors, poor dehumidifying coil performance results from the selection and installation of an oversized coil and the conventional strategy of modulating the chilled water flow rate as the only available control method. It is not uncommon to find that operating conditions demand a reduced chilled water flow rate not just during part load conditions but even during the actual peak load condition. Based on a simulation method that involves selection of coils for different conditions, this paper presents the findings of the performance evaluation of an oversized coil at different conditions during the operation stage. The findings show that the dehumidifying performance of the oversized coil at reduced loads during normal operation can be significantly enhanced by changing the effective surface area of the coil through a simple manipulation of the effective number of rows of coil operation.