Simulation and Analysis of the Control Effectiveness of TRVS in District Heating Systems

摘要

Based upon an existing building and heating system with thermostatic radiator valves (TRVs), an integrated model is developed for simulating the thermal and hydraulic behavior of the heating system under various operation cases. According to the simulation results, TRVs effectiveness of reducing the overheating phenomena has been studied. It is obtained that: when the set value of TRVs is kept at 2-3, TRVs effectiveness of reducing the overheating phenomena caused by excessive water flow rate is less than 60%; if the overheating phenomena is caused by excessive supply water temperature and radiator area, TRVs effectiveness can reach about 80%; the TRVs effect became more obvious with increasing overheating degree; however, about 0.2 to 0.4 proportion of overheating loss still needs to be resolved by improving improper operation adjustment and design. Considering those, a control strategy is proposed, in which the supply water temperature is daily adjusted according to the flow performance of the system, and the pump is operated with frequency conversion and constant pressure difference. Further simulation indicates that, under the new control strategy, the variation of heat supply quantity of the system can meet with the heat load change, and the flow rate of the system can be controlled at an appropriate range.