Effect of high temperatures on the efficiency of sub-critical CO2 cycle

Ahmed, Aram Mohammed; Imre, Attila R.

doi:10.1556/606.2021.00310

Cited by 7 publications

(1 citation statement)

References 26 publications

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“…The main target of WHR is to produce additional work, and a large quantity of waste heat can be converted into work from a high-quality heat source. Generally, Organic Rankine Cycle (ORC) system [1,2] and Steam Rankine Cycle (SRC) system [3,4] are contemplated as the most fruitful RWH techniques in the domain of low-grade heat and power generation stations, although other methods, like hot air (Stirling) engines can be also good for this purpose [4].…”

Section: Introductionmentioning

confidence: 99%

Analysis of CO2-based trans-critical power cycle in waste heat recovery

Atik

Imre

2023

Pollack

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Carbon-dioxide-based trans-critical power cycle is a novel technology for waste heat recovery. This technology can handle the high-temperature exhaust gas and can be built in a compact size, which is an important feature for the auxiliary equipment for an internal combustion engine. To obtain the best output, four configurations were constructed: the basic system; one with preheater, another with regenerator and a fourth with preheater and regenerator. Special features of supercritical CO2 make these cycles able to recover more energy than the traditional organic Rankine cycle. According to this study, heat regeneration increases thermal efficiency while preheating influences the net power output. Thus, it is beneficial to add both regenerator and preheater to the basic cycle.

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Section: Introductionmentioning

confidence: 99%

Analysis of CO2-based trans-critical power cycle in waste heat recovery

Atik

Imre

2023

Pollack

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Assessment of the thermal efficiency of subcritical power generation cycles using environmentally friendly fluids at various heat source temperatures

Ahmed

2022

Energy Science & Engineering

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This study aims to investigate the effect of the various heat source temperature (T max ) on thermal efficiency (η th ) for the organic rankine cycle (ORC), trilateral flash cycle (TFC), and partial evaporator (PE-ORC). For this purpose, HFE7000, HFE7100, and HFE7500 were used as working fluids (WFs). The results indicate that by using HFE7000, the maximum η th was obtained for all used power cycles and temperature ranges. Compared to HFE7100, HFE7500 has higher η th at TFC, and PE-ORC at low T max , while HFE7100 has the maximum value at high T max . The η th at T max = 353 K for TFC were 8.71%, 8.34%, and 8.59%, while for ORC 12.38%, 11.82%, and 11.71% for HFE7000, HFE7100, and HFE7500, respectively. At T max = 423 K for TFC were 17.65%, 16.26%, and 16.52%, while for ORC were 18.56%, 17.38%, and 16.59% for HFE7000, HFE7100, and HFE7500, respectively. The η th results indicate that the maximum improvement at TFC by using HFE7000, and the minimum was at HFE7100, while for ORC, the maximum was at HFE7000, and the minimum was at HFE7500. Therefore, the HFE7000 fluid behaves as normal dry fluids at any used temperature, while HFE7100 as normal dry WFs at low T max while behaving as very dry WFs at T max extremely close to its T cr . HFE7500 behaves as very dry working fluids. The η th intersections temperature was at T max = 425.2 K and T max = 455.9 K for HFE7500 and HFE7100, respectively. However, there is no η th intersection for HFE7000.

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Investigation of thermal efficiency for subcritical ORC and TFC using super dry working fluids

Ahmed

Imre

2022

Energy Science & Engineering

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Efficiency is a crucial factor for power cycles. Generally, in the same temperature range, the cycle efficiency for a basic organic Rankine cycle (ORC) is higher than a similar trilateral flash cycle (TFC) for almost all working fluids and heat source/heat sink temperature pairs. According to some recent results, by using super dry working fluids, the thermal efficiency of TFC can outperform its ORC counterpart at high temperatures. This study performed the thermodynamics analysis using three dry working fluids with subcritical basic ORC and TFC with zero to partial recuperated heat ratio. The results showed that using recuperative heat exchange effectively contributes to increasing the efficiency of ORC and TFC. However, the rate of efficiency increase in ORC is higher than the TFC, which can be clearly seen, especially at high maximal cycle temperatures. Using super dry working fluids, the recuperator‐free TFC has favorable cycle efficiency at high heat source temperatures. In contrast, by adding heat recovery for both systems, the ORC can outperform the TFC at 0.4, 0.2, and 0.1 recuperated heat effectiveness for Dodecane, Decane, and Nonane, respectively.

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Effect of high temperatures on the efficiency of sub-critical CO2 cycle

Cited by 7 publications

References 26 publications

Analysis of CO2-based trans-critical power cycle in waste heat recovery

Analysis of CO2-based trans-critical power cycle in waste heat recovery

Assessment of the thermal efficiency of subcritical power generation cycles using environmentally friendly fluids at various heat source temperatures

Investigation of thermal efficiency for subcritical ORC and TFC using super dry working fluids

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