3D Simulation of Ammonia Combustion in a Lean Premixed Swirl Burner
District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand
... the heat demand -outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract To date, a number of mechanical, electrical, thermal, and chemical approaches have been developed for storing electrical energy for utility-scale services. The only sufficiently flexible mechanism allowing large quantities of energy to be stored over long time periods is chemical energy storage in the form of carbon or hydrogen. One chemical considered for hydrogen carriage that can potentially be employed for storage is ammonia. Ammonia can substitute pure hydrogen for storage and be employed for power generation at large industrial scale if the molecule is efficiently burned through mature equipment such as gas turbines, thus providing not only a carbon free fuel, but also a chemical capable of being stored at low energy requirements. Thus, progress on the use of ammonia in gas turbines is a main priority for groups working on the area. Studies need to be conducted in experimental rigs with strong CFD analyses for further industrial implementation. In this paper, modelling of ammonia combustion in a generic gas turbine combustor is explored in order to provide an effective tool for future application. Large Eddy Simulation approach was used to develop a model for ammonia/hydrogen combustion in gas turbine combustors. To capture more details of the turbulent reacting flow, a detailed chemical mechanism was selected for a deep insight. A Partially Stirred Reactor framework was utilized to deal with the turbulence/chemistry interaction. The developed model was then applied to the simulation of lean premixed ammonia/hydrogen flames in a generic swirl burner. A preliminary validation for the model is performed by correlation of NOx emission with experimental data. Results show the model can provide detailed information of flow field, flame structure, emissions, etc. It can be used to optimize the procedure of utilizing ammonia as a fuel in future equipment design.