Abstract
To achieve carbon neutrality, there is a strong need for new energy-saving methods that can be easily applied to existing facilities that consume large amounts of energy. The purpose of this study is to save energy by improving the efficiency of the variable water volume control of cold and hot water. In our previous report, we showed that will be possible to reduce the differential pressure of the pump and improve the efficiency of the variable water volume control, by confirming the state of the air conditioning system. In addition, we reported that the energy consumption of the cold water secondary pump was reduced by 55% and the WTF was 350 or higher in existing facility. We then proposed several types of confirmation methods for reducing the differential pressure. Herein, we report the following the pressure verfications during an intermediate period. The effect on the capacity for further energy saving was examined at an existing facility. We also examined the reduction of the lower limit of the pump rotation speed and the further reduction of the differential when the hot water pressure was reduced. The analysis results show that the temperature difference between the cold and hot water flows increased owing to the reduction of the differential pressure. The WTF of cold water was 700 or higher, and the WTF of hot water was 350 or greater. The temperature difference was also 20°C or higher. Based on these verifications, we propose a method for confirming the air conditioning state and thus improve the efficiency of the variable water volume control by reducing the differential pressure.
