Entropy and Exergy Analysis of a Heat Recovery Vapor Generator for Ammonia-Water Mixtures

Kim, Kyoung Hoon; Kim, Kyoung-Jin; Ko, Hyung–Jong

doi:10.3390/e16042056

Cited by 9 publications

(3 citation statements)

References 24 publications

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“…In general, the phenomena that occur in the evaporator are subcooled, evaporating, and superheated zones. Based on the research of Kim et al [23] , evaporators with phase changes have high irreversibility. The evaporating zone produces a more significant two-phase heat transfer than the single-phase heat transfer at subcooled and superheated zones.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamic Analysis of Recuperative and Reheat Based on Organic Rankine Cycle for High-Temperature Waste Heat Recovery

Sakina

Nihayah

Ariwibowo

et al. 2023

JRM

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Heat recovery from available waste heat is an essential method in renewable energy processes due to the ability to generate electricity by using Organic Rankine Cycles (ORC). The process model is developed with the Cycle Tempo software. Fluid properties were analyzed with Reference Fluid Properties (REFPROP) software. This research presents a thermodynamic comparison of the Basic Organic Rankine Cycle (BORC) and Recuperative Organic Rankine Cycle (RORC) for waste heat recovery applications using pure refrigerants R-141b, R-245fa, R-123, and R-21. By performing simulations for heat source high-temperatures ranging from 160 to 200 °C. The comparison between BORC and RORC performance parameters and refrigerant properties was evaluated on the heat source temperature. Research shows that RORC produces higher thermal efficiency but has lower irreversibility than BORC. RORC has a maximum thermal efficiency of 12.67%, and BORC has a thermal efficiency of 11.49% for refrigerant R-141b at a flue gas temperature of 160 °C. The thermal efficiency of the ORC increases as the temperature of the heat source increases.

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Section: Resultsmentioning

confidence: 99%

Thermodynamic Analysis of Recuperative and Reheat Based on Organic Rankine Cycle for High-Temperature Waste Heat Recovery

Sakina

Nihayah

Ariwibowo

et al. 2023

JRM

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“…Thermodynamic analysis applied in scientific research that involves the First and Second Laws of Thermodynamics (FLT and SLT) allows to assess the performed processes in terms of quantity and quality. When applying the SLT, several values that define degradation of energy are encountered, for example, entropy and exergy [4,5], and, more rarely, entransy [6,7]. These indicators allow to demonstrate the true potential of a thermal system in terms of performance, therefore they become important when analyzing and comparing energy systems that use various types of energy [8].…”

Section: Introductionmentioning

confidence: 99%

From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit

Streckienė

Martinaitis

Bielskus

2019

Entropy

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The continuous energy transformation processes in heating, ventilation, and air conditioning systems of buildings are responsible for 36% of global final energy consumption. Tighter thermal insulation requirements for buildings have significantly reduced heat transfer losses. Unfortunately, this has little effect on energy demand for ventilation. On the basis of the First and the Second Law of Thermodynamics, the concepts of entropy and exergy are applied to the analysis of ventilation air handling unit (AHU) with a heat pump, in this paper. This study aims to develop a consistent approach for this purpose, taking into account the variations of reference temperature and temperatures of working fluids. An analytical investigation on entropy generation and exergy analysis are used, when exergy is determined by calculating coenthalpies and evaluating exergy flows and their directions. The results show that each component of the AHU has its individual character of generated entropy, destroyed exergy, and exergy efficiency variation. However, the evaporator of the heat pump and fans have unabated quantities of exergy destruction. The exergy efficiency of AHU decreases from 45–55% to 12–15% when outdoor air temperature is within the range of −30 to +10 °C, respectively. This helps to determine the conditions and components of improving the exergy efficiency of the AHU at variable real-world local climate conditions. The presented methodological approach could be used in the dynamic modelling software and contribute to a wider application of the Second Law of Thermodynamics in practice.

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“…For a review on its features and applications, readers may refer to Zhang et al [7]. As the isobaric phase change of ammonia-water mixture occurs at varying temperature, the thermal mismatch between fluids is alleviated to some extent or more, so that the irreversibility of the KC generated at the evaporator and condenser is kept low, resulting in a higher efficiency and an improvement in the cycle performance [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Comparative Thermodynamic Analysis of Kalina and Kalina Flash Cycles for Utilizing Low-Grade Heat Sources

Kim

Han

2018

Energies

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The Kalina flash cycle (KFC) is a novel, recently proposed modification of the Kalina cycle (KC) equipped with a flash vessel. This study performs a comparative analysis of the thermodynamic performance of KC and KFC utilizing low-grade heat sources. How separator pressure, flash pressure, and ammonia mass fraction affect the system performance is systematically and parametrically investigated. Dependences of net power and cycle efficiencies on these parameters as well as the mass flow rate, heat transfer rate and power production at the cycle components are analyzed. For a given set of separator pressure and ammonia mass fraction, there exists an optimum flash pressure making exergy efficiency locally maximal. For these pressures, which are higher for higher separator pressure and lower ammonia mass fraction, KFC shows better performance than KC both in net power and cycle efficiencies. At higher ammonia mass fraction, however, the difference is smaller. While the maximum power production increases with separator pressure, the dependence is quite weak for the maximum values of both efficiencies.

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Entropy and Exergy Analysis of a Heat Recovery Vapor Generator for Ammonia-Water Mixtures

Cited by 9 publications

References 24 publications

Thermodynamic Analysis of Recuperative and Reheat Based on Organic Rankine Cycle for High-Temperature Waste Heat Recovery

Thermodynamic Analysis of Recuperative and Reheat Based on Organic Rankine Cycle for High-Temperature Waste Heat Recovery

From Entropy Generation to Exergy Efficiency at Varying Reference Environment Temperature: Case Study of an Air Handling Unit

Comparative Thermodynamic Analysis of Kalina and Kalina Flash Cycles for Utilizing Low-Grade Heat Sources

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