| Heating energy consumption in the north of China has always been the focus of energy consumption. And central heating system optimal regulation and control is an important measure to realize energy saving implementation. Central heating system operation technology is not mature, and its automation level is not high. In order to make the room temperature can achieve better control effect, this paper investigates variable setpoint control strategy in differential pressure control loop in central heating system by means of simulation.Firstly, the math models of the main components in the system were established, including the systems model of hydraulic characteristics and thermal characteristics. According to the basic theory of Graph and Fluid Network, the math model of the pipeline network system was established. This work built a platform for simulation and calculation.Secondly, this paper investigates thermal characteristics of the central heating system, including radiator thermal characteristics and the thermal characteristics of the system without a control system. By analyzing the rule of the temperature variation, we determine the most unfavorable pipe and its most unfavorable room. It provides the basis for the optimized allocation of temperature sensor in monitoring and controlling system.Thirdly, according to the most unfavorable hydraulic loop, a novel variable differential pressure setpoint control strategy is proposed. This paper investigates the feasibility of presented strategy by Using the simulated model of central heating system,Finally, in order to evaluate the effect of the control scheme, this paper studies the application effect of the three strategies by simulation based on thermodynamics stability as evaluation parameter. Simulation results show that variable differential pressure setpoint control strategy has a great significant energy saving effect. However, differential pressure setpoint needs to be selected with reference of thermodynamic stability. |
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