| Popis: |
District heating is an efficient and promising way to cover the residential space-heating and domestic hot waterneeds, resulting in economic and environmental benefits, especially if operated by renewable power stations,when compared to fossil fuels. In this direction, the present study investigates in detail a district heating networkwith novel decentralized storage for domestic hot water (enerboxx scenario), over centralized storage systems,applying a specific schedule-based approach for the coordinated hot water tank charging. The goal of this designis to properly control the system by charging it at predetermined time periods during the day aiming at i)diminishing the thermal losses and ii) reducing the thermal demand from the grid, over the period of a day. Thesimulation is conducted with a newly developed component-based tool, called INTEMA, which is based on theModelica language. This encompasses the ability to discretize with high temporal resolution and adjustable timesteps the overall grid configuration, with the support of customizable level of detail models for simulating keysystem components such as the storage tanks, the piping and the dwelling needs, as well as the application of anadvanced control system over the district heating network and the dwellings. More specifically, a combinedcontrol system that controls both operating parameters in the network and inside the dwellings is applied. Thedeveloped system model is verified against available data for a standard centralized storage system (referencescenario) and afterwards, the novel decentralized design is compared against corresponding results of thestandard system, as concerns key operational parameters; indicatively the temperature levels of the hot waterand the heat load demand. The analysis is conducted for a heating network of 9 dwellings in Austria, which havean underfloor heating system, a system for covering the domestic hot water demand, considering also that eachof these 9 dwellings is characterized by a unique demand profile. It was found that the decentralized approachleads to lower demand and there are energy savings of 18 % compared to the reference scenario, while thethermal losses are reduced by about 22 %. Moreover, a parametric study regarding the storage tank volume and the heat exchanger thermal transmittance in the tank is conducted, in order to examine the impact of thesedesign parameters on the system dynamic behavior. |
