Energy-balance Method And Its Application On Radiant Floor Heating System

With the increase of people’s thermal comfort requirements of indoorenvironment, and due to the great promotion of energy conservation by the wholesociety, the regulation of Central Heating Supply System (CHSS) has been a focusof concern at present. However, both the characteristics of CHSS composed of largeheating supply area, multiple influence factors and intricate non-linear matters, andthe late-starting research status lead to lacking effective automatic control methodsof CHSS regulation in China.In consideration of the aforementioned problems, this study proposes a novelautomatic control method of CHSS regulation Energy-balance method (E-method).This method is based on the energy balace of CHSS. The energy CHSS provided isfeedback variable, while the energy that radiating terminal equipment shed at theset temperature is the reference input. Based on these, the CHSS is regulated byadjusting the flow and the temperature of supply water. The greatest feature ofE-method is that there is no need to installing the temperature sensor in the building.By means of theoretical study and system operation analysis, this study verifies thefeasibility of E-method, and at the same time, in terms of the control procedure, thecontrol effect and the application advantage can be synthetically evaluated andanalyzed.First of all, this paper introduces and analyses the control object, the controlprinciple and the core of the control method; and then provides the constitute formof E-method automatic control system, which consists of hardware equipments andsoftware program design process; and puts forward relevant E-method controlschemes against no mixing-water direct connection heating system andmixing-water direct connection heating system, in which the system hardwareequipment installation connection mode and the overall control thought aredetailedly discussed.Secondly, based on E-method, the radiant floor heating system demonstrationproject has been reformed as automatic control project in the School of Municipaland Environmental Engineering of Harbin Institute of Technology. The detailed introduce about reform process illustrates that E-method can be compatibly appliedin the automatic control reform of original heating system. By the analysis of thereformed system operation and the comparison of building indoor temperaturebetween before and after reforming, this paper discusses the control process ofE-method, meanwhile verifies the feasibility of this control method. The thermalinertia of radiant floor heating system, however, is comparatively large, which maycause the system requiring a long period of time to achieve stabilize.And also, the analysis calculations on heating system energy consumptionbefore and after reforming, confirms the energy conservation effect of E-methodautomatic control system. The result shows that the application of this automaticcontrol method on heating system can effectively decrease pump operation energyconsumption the system no less than60%.Finally, due to the problems existed in the operation process of E-methodautomatic control system, and the characteristics of large thermal inertia of radiantfloor heating system, this paper proposes the modified scheme against control logic.The comparison analysis between before and after reforming the control logic,verifies that the modified control logic can ultimately solve the system operationproblem that the mixing water pump adjusts too fast.