Abstract
This study aims to discuss the effectiveness of “Demand-Supply Coordinated control” in reducing the power consumption required for conveyance by the heat transport medium in District Cooling and Heating (DHC) systems. The problem with DHC systems is that increased conveyance power is required to provide heating to consumers. As one of the measures to solve this problem, Demand-Supply Coordinated (DSC) control is introduced; however, its effectiveness and limitations have not been clarified so far. In this paper, first, the fundamental characteristics of a DHC system under DSC control are numerically examined. The results showed that the conveyance power consumption of DHC systems under DSC control can be classified into three regions, depending on the relative rate of demand change against the load-following capability of the heat source. Next, the authors compared the conveyance power of DSC control with that of Constant Supply Pressure (CSP) control adopted in conventional DHC, and showed regularity for each of the three regions mentioned above. Finally, the authors show the appearance frequency of these three regions of the practical DHC system under a real heat load in Japan. The results showed that the conveyance power required for DSC control is markedly lower than that of CSP control.
Highlights
District cooling and heating (DHC) systems aim to introduce an efficient large-scale concentrated heat source for supplying heat to multiple buildings in a specific area in order to reduce the energy consumption in the whole area
Heat demand fluctuation was assumed by sinusoidal functions, and the conveyance power consumption of DHC systems with heat source equipment having different load-following capabilities was evaluated for various rates of heat demand change
The results showed that the conveyance power consumption of DHC systems under Demand-Supply Coordinated (DSC) control can be classified into three regions, depending on the relative rate of demand change against the loadfollowing capability of the heat source
Summary
District cooling and heating (DHC) systems aim to introduce an efficient large-scale concentrated heat source for supplying heat to multiple buildings in a specific area in order to reduce the energy consumption in the whole area. This is a function to control energy at the district level in a planar and optimal manner using information communication technology By introducing this into DHC systems, DSC control including the heat supply side, and the heat demand side, becomes possible, and more effective reduction of conveyance power can be realized. In the case of one heat consumer, basic characteristics of the conveyance power in DHC systems with DSC control were discussed focusing on the relative thermal load fluctuation rate to the load following speed of the heat source machine. The authors concluded that significant energy savings can be realized by introducing DSC control into practical DHC systems in a certain site in Tokyo area, because thermal load fluctuation faster than the following speed of the heat source machine seldom appears under the practical conditions.
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