Retro-Commissioning and Improvement for District Heating and Cooling System Using Simulation

Abstract

In order to improve the energy performance of a district heating and cooling (DHC) system, retro-commissioning was analyzed using visualization method and simulation based on mathematical models, and improved operation schemes were proposed according to simulation analysis results. The first part of this paper describes the system performance through visualizing the current operation modes. The second part introduces the retro-commissioning analysis for the system using mathematical models of each component. The third part studies the energy and cost performance of several improved operation proposals using simulation. The results are as follows.1) The carpet plots of current operation modes can be generated automatically and they are useful to check whether the operation is proper or not. 2) The total system simulation model was constructed. The simulation error of the total energy consumption was 1.5% and the percentage of root mean square error (%RMSE) was 16.3%, which show that the simulation is accurate enough to study the performance of proposed operation.3) System simulations for proposed operation schemes were performed. The simulation results show that the system operation with the optimal temperature set point of cooling water at 22oC can improve the total energy coefficient of the heat pump and cooling tower by 2.2 %. Another proposal is that if the return water temperature from users can be kept at the designed value, which is 13±1? compared with the current average value of 10.5?, the total energy consumption can be reduced by 9.5%, and energy cost can be reduced by 11.6%.