Implications of the modelling of stratified hot water storage tanks in the simulation of CHP plants

• Published in: Energy conversion and management Vol. 52; no. 8; pp. 3018 - 3026
• Main Authors: Campos Celador, A., Odriozola, M., Sala, J.M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2011; Elsevier
• Subjects: Advanced exergetic analysis; Applied sciences; Cogeneration; Combined power plants; Computer simulation; Economic data; Electric energy; Energy; Energy economics; Energy. Thermal use of fuels; Exact sciences and technology; Exergy; Feasibility; Feasibility studies; General, economic and professional studies; Hot water; Installations for energy generation and conversion: thermal and electrical energy; Mathematical models; Modelling; Simulation; Storage tanks; Stratified thermal storage; Transport and storage of energy; Europe; Spain; Spain, Pais Vasco, Vizcaya, Bilbao; Stratified thermal storage; Feasibility; Cogeneration; Simulation; Advanced exergetic analysis; Performance evaluation; Economic analysis; Heat production; Urban area; Thermal stratification; Modeling; Case study; Hot water storage; Energetic efficiency; Technicoeconomic study; Electric power production; Exergetic efficiency; Cost analysis; Storage tank; Combined power plant; Residential sector
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2011.04.015

► Three different modelling approaches for simulation of hot water tanks are presented. ► The three models are simulated within a residential cogeneration plant. ► Small differences in the results are found by an energy and exergy analysis. ► Big differences between the results are found by an advanced exergy analysis. ► Results on the feasibility study are explained by the advanced exergy analysis. This paper considers the effect that different hot water storage tank modelling approaches have on the global simulation of residential CHP plants as well as their impact on their economic feasibility. While a simplified assessment of the heat storage is usually considered in the feasibility studies of CHP plants in buildings, this paper deals with three different levels of modelling of the hot water tank: actual stratified model, ideal stratified model and fully mixed model. These three approaches are presented and comparatively evaluated under the same case of study, a cogeneration plant with thermal storage meeting the loads of an urbanisation located in the Bilbao metropolitan area (Spain). The case of study is simulated by TRNSYS for each one of the three modelling cases and the so obtained annual results are analysed from both a First and Second-Law-based viewpoint. While the global energy and exergy efficiencies of the plant for the three modelling cases agree quite well, important differences are found between the economic results of the feasibility study. These results can be predicted by means of an advanced exergy analysis of the storage tank considering the endogenous and exogenous exergy destruction terms caused by the hot water storage tank.