Experimental study on characteristics of a dual temperature control valve in the chilled water system of an air-conditioning unit

Abstract The excess flow of water increases the energy consumption of water pumps in the chilled water systems of air-conditioning units. This paper proposes a strategy to control the chilled water flow rate of a fan coil unit (FCU) using a control valve. A physical simulation test bench was built to verify valve control and energy-saving effects. Results showed that the control valve could effectively regulate the flow rate of chilled water, improve the temperature difference (delta-T) between supply and return water, and reduce the energy consumption of the chilled water pump. With a supply water temperature of 7 C and low (325 m3⋅h−1), medium (500 m3⋅h−1), and high (600 m3⋅h−1) FCU air velocity levels, the average delta-T values were 4.79  °C, 4.39  °C, and 4.97  °C, respectively, and the energy consumption of the chilled water pump decreased by 12.20%, 11.31%, and 10.66%, respectively. With medium air velocity and supply water temperatures of 7  °C, 8  °C, and 9  °C, the average delta-T between supply and return water was 4.39  °C, 3.56  °C, and 3.33  °C, respectively, and the energy consumption of the chilled water pump decreased by 11.31%, 5.10%, and 7.80%, respectively. These research results provide useful insights in relation to the problem of excess chilled water flow identified above.