A Flow Rate Control Approach on Off-Design Analysis of an Organic Rankine Cycle System
Abstract
:1. Introduction
2. System Description and Methodology
3. Results and Discussion
3.1. Operating Flow Rate and Temperature Distribution
3.2. Pinch Point and Logarithmic Mean Temperature Differences
3.3. Heat Transfer Characteristics
3.4. Net Power Output
4. Conclusions
- (1)
- The operation flow rate of R245fa increased with increasing TW,in or mW. Differences in pinch point temperatures of the heat exchanger system, except for cases of higher TW,in, were appropriate regarding the ORC system performance.
- (2)
- A higher TW,in or mW yielded better heat transfer performance of the designed preheater, primarily resulting from the increase in ΔTlm,pre, and required the evaporator’s heat capacity to be higher, which is attributable to increases in both Ueva and ΔTlm,eva.
- (3)
- Heat transfer characteristics of the preheater and evaporator, such as logarithmic mean temperature differences and shell- and tube-side heat transfer coefficients, showed different trends for off-design TW,in and mW.
- (4)
- Net power output increased linearly with increasing TW,in or mW. The flow rate control of R245fa within heat source temperature (flow rate) variations of −10.3 to +19.8 °C (−6 to +12 kg/s) from design temperature (flow rate) resulted in variations of −24.7% to +45.3% (−32.5% to +49.4%) in the net power output.
- (5)
- Regarding maximum net power output, the flow rate control approach is the optimal strategy when TW,in or mW exceeds the design point, but the pressure control approach is better when TW,in or mW is lower than the design point.
Acknowledgments
Conflicts of Interest
References
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Fu, B.-R. A Flow Rate Control Approach on Off-Design Analysis of an Organic Rankine Cycle System. Energies 2016, 9, 759. https://doi.org/10.3390/en9090759
Fu B-R. A Flow Rate Control Approach on Off-Design Analysis of an Organic Rankine Cycle System. Energies. 2016; 9(9):759. https://doi.org/10.3390/en9090759
Chicago/Turabian StyleFu, Ben-Ran. 2016. "A Flow Rate Control Approach on Off-Design Analysis of an Organic Rankine Cycle System" Energies 9, no. 9: 759. https://doi.org/10.3390/en9090759