Behnaz Rezaie

Exergy Assessment of a Solar-Assisted District Energy System

Method: A case study based on the Friedrichshafen DE system in Germany is used to assess thermodynamically the role of solar energy and TES in a DE system. The system performance is separated into three modes: (1) fossil fuel is the only source of energy, (2) a discharging TES and fossil fuel provide heat for the DE system, and (3) solar energy and fossil fuels are the energy supplies. Exergy analyses are conducted for each performance mode and the overall DE system.

Work Availability and Exergy Analysis

Pouria Ahmadi 1,* and Behnaz Rezaie 2 ID 1 Institute for Sustainability, Energy, and Environment (ISEE), University of Illinois at Urbana-Champaign (UIUC), Urbana, IL 61802, USA 2 Applied Energy Research Laboratory, Department of Mechanical Engineering, University of Idaho, 875 Perimeter Drive, MS 0902, Moscow, ID 83844-0902, USA; rezaie@uidaho.edu * Correspondence: Pahmadi@illinois.edu or pouryaahmadi81@gmail.com

Evaluation of Sustainable Energy Options for Non-residential Buildings

The building sector, as the major energy consumers, demands most of the energy research to assess different energy suppliers from various aspects. In this study, two non-residential buildings, one being commercial and the other industrial, are chosen as case studies. For these case studies, two different renewable energy technologies and one hybrid system are considered for a specified size. The environmental impact indices, renewable energy indices, and the renewable exergy indices have been evaluated for every energy options. The results obtained indicate that the hybrid system (without considering the economics factors) is superior since having top indices. The importance of the energy consumption patterns in buildings were proven by the indices. Utilization of the non-fossil fuels is one part of the solution to environmental hazards while energy conservation being the other. It is shown that the re-design of the energy resources would be achievable for buildings.

Thermodynamic Assessment of Seasonal Stratified Thermal Storage

District energy (DE) and thermal energy storage (TES) are two energy technologies that can enhance the efficiency of energy systems. Also, DE and TES can help address global warming and other environmental problems. In this study, a stratified TES is assessed using exergy analysis, to improve understanding of the thermodynamic performance of the stratified TES, and to identify energy and exergy behavioural trends. The analysis is based on the Friedrichshafen DE system, which incorporates seasonal TES, and which uses solar energy and fossil fuel. The overall energy and exergy efficiencies for the Friedrichshafen TES are found to be 60 and 19 % respectively, when accounting for thermal stratification. It is also found that stratification does not improve the performance of the TES notably. Considering the TES as stratified and fully mixed does not significantly affect the overall performance of the Friedrichshafen TES because, for this particular case, temperatures are very close whether the TES is treated as stratified or fully mixed.