Thermodynamic Analysis of Low-Temperature Power Generation Transcritical Rankine Cycle With R41 and CO2

2014 ◽  
Author(s):  
Jixiang Liao ◽  
Qun Zheng
Keyword(s):  
Power Generation ◽  
Renewable Energy ◽  
Low Temperature ◽  
Rankine Cycle ◽  
Second Law ◽  
Average Value ◽  
Comprehensive Performance ◽  
Lower Temperature ◽  
Net Power Output ◽  
Transcritical Rankine Cycle

The performances of the transcritical Rankine cycles using R41 and CO2 as working fluids for power generation with lower temperature renewable energy are analyzed respectively and presented in this paper. The results show that the R41 cycle displays better comprehensive performance than that of the CO2 cycle. Compared with the CO2 cycle under the same specified conditions, the average value of the maximum net power output increased by more than 52.6%, the optimum inlet pressure decreased by over 41.6% and the second law efficiency increased by 24.8%. Moreover, the system thermal efficiency of R41 cycle is slightly higher than that of the CO2 cycle.

Analysis and Optimization of an Ammonia Based Transcritical Rankine Cycle for Power Generation

2008 ◽  
Author(s):  
Jahar Sarkar ◽  
Souvik Bhattacharyya
Keyword(s):  
Power Generation ◽  
Low Temperature ◽  
Thermal Efficiency ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Heat Sources ◽  
High Side ◽  
Water Based ◽  
Temperature Heat ◽  
Transcritical Rankine Cycle

This study presents the potential of ammonia as a working fluid in transcritical Rankine cycle for power generation using both high and low temperature heat sources. Higher heat capacity value and superior heat transfer properties of ammonia compared to water are the motivating factors behind its use as a working fluid. A thermodynamic analysis for the ammonia based transcritical Rankine cycle and its comparison with the water based Rankine cycle is presented. Analyses with several cycle modifications are also presented to study the thermal efficiency augmentation. It is observed that an optimum high side pressure exists for near critical operation. In case of low temperature heat sources such as solar energy or waste heat, where water based systems are not suitable, ammonia based Rankine cycle is applicable with attractive thermal efficiency, although cycle modification is not possible. The results with high temperature heat source such as boiler or nuclear reactor, where the turbine outlet is in superheated zone, show that simple ammonia systems yield lower efficiency than water, although a recompression cycle with regenerative heat exchangers exhibits higher efficiency than water. Significant thermal efficiency improvement can be achieved by increasing the high side cycle pressure. Recompression Rankine cycle can be a potential alternative with proper design measures taken to avoid toxicity and flammability.

scholarly journals Investigation of an Innovative Cascade Cycle Combining a Trilateral Cycle and an Organic Rankine Cycle (TLC-ORC) for Industry or Transport Application

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3032 ◽  
Author(s):  
Xiaoli Yu ◽  
Zhi Li ◽  
Yiji Lu ◽  
Rui Huang ◽  
Anthony Roskilly
Keyword(s):  
High Temperature ◽  
System Performance ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Second Law ◽  
Exergy Destruction ◽  
Second Law Analysis ◽  
Net Power Output

An innovative cascade cycle combining a trilateral cycle and an organic Rankine cycle (TLC-ORC) system is proposed in this paper. The proposed TLC-ORC system aims at obtaining better performance of temperature matching between working fluid and heat source, leading to better overall system performance than that of the conventional dual-loop ORC system. The proposed cascade cycle adopts TLC to replace the High-Temperature (HT) cycle of the conventional dual-loop ORC system. The comprehensive comparisons between the conventional dual-loop ORC and the proposed TLC-ORC system have been conducted using the first and second law analysis. Effects of evaporating temperature for HT and Low-Temperature (LT) cycle, as well as different HT and LT working fluids, are systematically investigated. The comparisons of exergy destruction and exergy efficiency of each component in the two systems have been studied. Results illustrate that the maximum net power output, thermal efficiency, and exergy efficiency of a conventional dual-loop ORC are 8.8 kW, 18.7%, and 50.0%, respectively, obtained by the system using cyclohexane as HT working fluid at THT,evap = 470 K and TLT,evap = 343 K. While for the TLC-ORC, the corresponding values are 11.8 kW, 25.0%, and 65.6%, obtained by the system using toluene as a HT working fluid at THT,evap = 470 K and TLT,evap = 343 K, which are 34.1%, 33.7%, and 31.2% higher than that of a conventional dual-loop ORC.

Performance Investigation of Solar Organic Rankine Cycle System With Zeotropic Working Fluid Mixtures for Use in Micro-Cogeneration

2021 ◽  
Vol 143 (9) ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev ◽  
Pouyan Talebizadehsardari ◽  
Michela Longo
Keyword(s):  
Low Temperature ◽  
Power Output ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Condensation Temperature ◽  
Source Temperature ◽  
Thermodynamic Performance ◽  
Net Power Output ◽  
Cycle Efficiency

Abstract Overall, there are numerous sustainable sources of renewable, low-temperature heat, principally solar energy, geothermal energy, and energy produced from industrial wastes. Extended utilization of these low-temperature alternatives has a certain capacity of decreasing fossil fuel use with its associated very hazardous greenhouse gas emissions. Researchers have commonly recognized the organic Rankine cycle (ORC) as a feasible and suitable system to produce electrical power from renewable sources based on its advantageous use of volatile organic fluids as working fluids (WFs). Researchers have similarly shown an affinity to the exploitation of zeotropic mixtures as ORC WFs due to their capability to enhance the thermodynamic performance of ORC systems, an achievement supported by improved fits of the temperature profiles of the WF and the heat source/sink. This paper determines both the technical feasibility and the benefits of using zeotropic mixtures as WFs by means of a simulation study of an ORC system. This study analyzes the thermodynamic performance of ORC systems using zeotropic WF mixtures to produce electricity driven by low-temperature solar heat sources for use in buildings. A thermodynamic model is created with an ORC system with and without a regenerator. Five zeotropic mixtures with diverse compositions between 0 and 1 in 0.2 increments of R245fa/propane, R245fa/hexane, R245fa/heptane, pentane/hexane, and isopentane/hexane are assessed and compared with identify the best blends of mixtures that are able to produce superior efficiency in their system cycles. Results disclosed that R245fa/propane (0.4/0.6) with regenerator produces the highest net power output of 7.9 kW and cycle efficiency of 9.4% at the operating condition with a hot source temperature of 85 °C. The study also investigates the effects of the volume flow ratio, and evaporation and condensation temperature glide on the ORC’s thermodynamic performance. Following a thorough analysis of each mixture, R245fa/propane is chosen for a parametric study to examine the effects of operating factors on the system’s efficiency and sustainability index. It was found that the highest cycle efficiency and highest second law cycle efficiency of around 10.5% and 84.0%, respectively, were attained with a mass composition of 0.6/0.4 at the hot source temperature of 95 °C and cold source temperature of 20 °C with a net power output of 9.6 kW. Moreover, results revealed that for zeotropic mixtures, there is an optimal composition range within which binary mixtures are tending to work more efficiently than the component pure fluids. In addition, a significant increase in cycle efficiency can be achieved with a regenerative ORC, with cycle efficiency in the range 3.1–9.8% versus 8.6–17.4% for ORC both without and with regeneration, respectively. In conclusion, utilizing zeotropic mixtures may well expand the restriction faced in choosing WFs for solar-powered ORC-based micro-combined heat and power (CHP) systems.

scholarly journals Supercritical Rankine Cycle Coupled with Ground Cooling for Low Temperature Power Generation

2014 ◽  
Vol 57 ◽  
pp. 524-532 ◽  
Author(s):  
Rachana Vidhi ◽  
D. Yogi Goswami ◽  
Elias Stefanakos
Keyword(s):  
Power Generation ◽  
Low Temperature ◽  
Rankine Cycle

scholarly journals Investigation of a thermo-fluidic exchange pump in trilateral flash and organic Rankine cycles / trans. from Engl. M. A. Fedorova

2020 ◽  
Vol 4 (4) ◽  
pp. 66-74
Author(s):  
C. R. Baggley ◽  
◽  
M. G. Read ◽  
Keyword(s):  
Low Temperature ◽  
Power Output ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Vapour Phase ◽  
Working Fluid ◽  
Positive Displacement ◽  
Wide Range ◽  
Work Input ◽  
Net Power Output

It is well known that large amounts of energy loss occurs at low temperature states in a wide range of industrial processes., The recovery and reuse of this energy is at the forefront of increasing the overall efficiencies of industrial systems. The aim of this paper is to investigate the effectiveness of using a Thermo-Fluidic Exchange (TFE) pump at low temperature conditions in both a SaturatedVapour Organic Rankine Cycle (SORC) and a Trilateral Flash Cycle (TFC). For some low temperature applications, TFCs have been shown to achieve higher net power output than conventional SORCs, due to their ability to extract more heat from the source fluid. This is the subject of current research as a result of advancements made in the design of positive displacement machines for operation as twophase expanders. Conventional turbines cannot be used for TFCs as they must operate in the vapour phase. One drawback of the TFC is the higher working fluid mass flow rate required. Depending on the scale of the system, this can potentially cause difficulties with pump selection. A TFE pump uses heat input to the system to increase the pressure and temperature of the working fluid, rather than the work input in a standard mechanical pump. This paper compares the net power output achievable using both mechanical and TFE pumps with SORC and TFC systems. The results suggest that the TFE pump could be a viable option for TFC systems

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