Performance enhancement of a complex chilled water system using a check valve: experimental validation

The large primary-secondary chilled water systems often suffer from the excess flow demand and low chilled water temperature difference, which is known as the low ΔT central plant syndrome, during operation. This paper presents an approach for experimental validation of the possible utility of a check valve (i.e., putting a one-direction check valve in the chilled water by-pass line) to solve this operational problem and enhance the overall system performance, prior to a check valve is really installed. The experimental tests were carried out on the complex central chiller plant in a super high-rise building using a simulated check valve through fully closing one of the butterfly valves in the by-pass line when the system operated with a significant excess flow demand and experienced the low ΔT syndrome. The results from the tests showed that the system operational performance can be improved when the simulated check valve was used. Compared to that without using the check valve, about 9.2% of the total energy of the chillers and secondary water pumps was saved in the test period when the simulated check valve was used.