Exergy Analysis of a Combined Power and Refrigeration Thermodynamic Cycle Driven by a Solar Heat Source

2003 ◽  
Vol 125 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Afif Akel Hasan ◽  
D. Y. Goswami
Keyword(s):  
Heat Source ◽  
Exergy Analysis ◽  
Thermodynamic Cycle ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Water Mixture ◽  
Exergy Destruction ◽  
Ammonia Water ◽  
Solar Heat

Exergy thermodynamics is employed to analyze a binary ammonia water mixture thermodynamic cycle that produces both power and refrigeration. The analysis includes exergy destruction for each component in the cycle as well as the first law and exergy efficiencies of the cycle. The optimum operating conditions are established by maximizing the cycle exergy efficiency for the case of a solar heat source. Performance of the cycle over a range of heat source temperatures of 320–460°K was investigated. It is found that increasing the heat source temperature does not necessarily produce higher exergy efficiency, as is the case for first law efficiency. The largest exergy destruction occurs in the absorber, while little exergy destruction takes place in the boiler.

Performance Improvement of an Ammonia-Water Mixture Turbine Cycle With Ejector

2005 ◽  
Author(s):  
Yoshiharu Amano ◽  
Keisuke Takeshita ◽  
Takumi Hashizume
Keyword(s):  
Heat Source ◽  
Pressure Difference ◽  
Heat Recovery ◽  
Preliminary Investigation ◽  
Thermal Conductance ◽  
Thermodynamic Cycle ◽  
Specific Power ◽  
Water Mixture ◽  
Ammonia Water ◽  
The Impact

This paper presents the results of a preliminary investigation into the effect of installing an ejector in an ammonia-water mixture turbine cycle, also called a Kalina cycle. To enhance the availability of the cycle, we focus on the pressure difference in the cycle. The temperature difference between the heat source and sink enhances the efficiency of the thermodynamic cycle, as does the pressure difference in the cycle. To improve the heat recovery in the cycle, other heat exchangers are required, and to utilize the pressure difference in the cycle, an ejector is a reasonable choice. From the viewpoint of the impact on the initial cost of the plant, the heat exchanger option is more costly than the ejector option. The authors investigated a simple AWM turbine cycle with an ejector driven by the high-pressure solution stream to vacuum the turbine exhaust. Simulations of several AWM turbine cycle configurations, with or without heat recovery exchangers and ejectors were performed. The specific power, which is the output power per unit mass flow rate of the heat source, of the proposed cycle EJT34 was 103% that of the WMTS. The thermal conductance is only about 24% of that of the WMTS, which is almost the same as the value of the KCS34. The results shows that the EJT34 produced as much power as that from the WMTS with 24% of the heat transfer area.

Experimental Results of an Ammonia-Water Mixture Turbine System: Part 2 — Effect of the Ammonia Mass Fraction

2002 ◽  
Author(s):  
Keisuke Takeshita ◽  
Yoshiharu Amano ◽  
Takumi Hashizume ◽  
Akira Usui ◽  
Yoshiaki Tanzawa
Keyword(s):  
Heat Source ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Mass Fraction ◽  
Supply System ◽  
Operating Conditions ◽  
Experimental Results ◽  
Water Mixture ◽  
Experimental Facility ◽  
Ammonia Water

This paper is an additional report to the paper by Amano (2001). In this paper, the authors report the additional experimental results of the effect of an ammonia mass fraction at the inlet of the AWM (Ammonia-Water Mixture) vapor generator in the AWM turbine system. The AWM turbine system features the Kalina Cycle technology. The 70KW-experimental facility was built in order to gain knowledge for practical applications. The heat source is the exhaust steam from a back-pressure steam turbine. The AWM turbine system is installed at the bottoming stage of a combined cycle which has a gas turbine, a steam turbine and an AWM turbine for cascade utilization of heat. The authors designed and constructed an experimental facility, the ACGS (the Advanced Co-Generation System), to investigate various energy-saving technologies for a distributed energy supply system in the Advanced Research Institute for Science and Engineering at Waseda University. One of the main targets is a hybrid combined heat and power supply system that uses AWM as its working fluid. The AWM turbine system was developed for the bottoming stage of a “trinary turbine cycle system” which is composed of a gas turbine, a steam turbine and the AWM turbine systems. The experimental results of the ammonia mass fraction to the cycle efficiency are investigated with a range of the ammonia mass fraction between 0.4 [NH3kg/kg] to 0.7 [NH3kg/kg]. It shows that there are optimal operating conditions depending on the heat source temperature with an ammonia mass fraction of the cycle. The simulation model of the AWM turbine system shows good agreement with the experimental data.

Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources, Part II: Experimental Investigation

2003 ◽  
Vol 125 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Gunnar Tamm ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperature ◽  
System Analysis ◽  
Waste Heat ◽  
Thermal Power ◽  
Experimental System ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Water Mixture ◽  
Theoretical Simulation

A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally, exhibiting expected trends, but with deviations from ideal and equilibrium modeling. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating conditions.

scholarly journals Thermodynamic analysis and simulation of a new combined power and refrigeration cycle using artificial neural network

2011 ◽  
Vol 15 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Abdolreza Fazeli ◽  
Hossein Rezvantalab ◽  
Farshad Kowsary
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Heat Source ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
Artificial Neural

In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN) is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

A Totally Heat-Driven Refrigeration System Using Low-Temperature Heat Sources for Low-Temperature Applications

2019 ◽  
Vol 27 (02) ◽  
pp. 1950012 ◽  
Author(s):  
Zeynab Seyfouri ◽  
Mehran Ameri ◽  
Mozaffar Ali Mehrabian
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
Refrigeration System ◽  
Power Requirement ◽  
Temperature Heat

In the present study, a totally heat-driven refrigeration system is proposed and thermodynamically analyzed. This system uses a low-temperature heat source such as geothermal energy or solar energy to produce cooling at freezing temperatures. The proposed system comprises a Rankine cycle (RC) and a hybrid GAX (HGAX) refrigeration cycle, in which the RC provides the power requirement of the HGAX cycle. An ammonia–water mixture is used in both RC and HGAX cycles as the working fluid. A comparative study is conducted in which the proposed system is compared with two other systems using GAX cycle and/or a single stage cycle, as the refrigeration cycle. The study shows that the proposed system is preferred to produce cooling at temperatures from 2∘C to [Formula: see text]C. A detailed parametric analysis of the proposed system is carried out. The results of the analysis show that the system can produce cooling at [Formula: see text]C using a low-temperature heat source at 133.5∘C with the exergy efficiency of about 20% without any input power. By increasing the heat source temperature to 160∘C, an exergy efficiency of 25% can be achieved.

Performance of Working Fluids for Power Generation in a Supercritical Organic Rankine Cycle

2012 ◽  
Author(s):  
Rachana Vidhi ◽  
Sarada Kuravi ◽  
Saeb Besarati ◽  
E. K. Stefanakos ◽  
D. Yogi Goswami ◽  
...  
Keyword(s):  
Power Generation ◽  
Heat Source ◽  
Thermal Efficiency ◽  
Thermodynamic Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluids ◽  
Source Temperature ◽  
Heat Source Temperature ◽  
Organic Fluids

This paper reports on the performance of various organic refrigerants and their mixtures as working fluids for power generation in a supercritical Rankine cycle (SRC) from geothermal sources. Organic fluids that have zero or very low ozone depletion potential and are environmentally safe are selected for this study. Geothermal source temperature is varied from 125–200°C, and the cooling water temperature is changed from 10–20°C. The effect of varying operating conditions on the performance of the thermodynamic cycle has been analyzed. Operating pressure of the cycle has been optimized for thermal efficiency for each fluid at each source temperature. The condensation pressure is determined by the cooling condition and is kept fixed for each condensation temperature. Energy and exergy efficiencies of the cycle have been obtained for the pure fluids as a function of heat source temperature. Mixtures of organic fluids have been analyzed and effect of composition on performance of the thermodynamic cycle has been studied. It is observed that thermal efficiency over 20% can be achieved for 200°C heat source temperature and the lowest cooling temperature. When mixtures are considered as working fluids, the thermal efficiency of the cycle is observed to remain between the thermal efficiencies of the constituent fluids.

A New Multidimensional Graph for the Einstein Refrigeration Cycle

2006 ◽  
Author(s):  
Araceli Lara V. ◽  
David Sandoval C. ◽  
Juan Morales G. ◽  
Raymundo Lo´pez C. ◽  
Arturo Lizardi R. ◽  
...  
Keyword(s):  
Binary Systems ◽  
Graphical Representation ◽  
Rankine Cycle ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
Exergy Destruction ◽  
Ammonia Water ◽  
Equilibrium Data ◽  
Multidimensional Representation ◽  
Thermodynamic Processes

An analysis of the exergy use in an Einstein refrigeration cycle is presented. The analysis is performed through the use of a new graphical multidimensional representation of the cycle. The Einstein refrigeration cycle works with ammonia, butane and water. These compounds are present in the cycle as several ammonia-water and ammonia-butane mixtures that have different compositions. In essence, the cycle transfers ammonia from an ammonia-water mixture to an ammoniabutane mixture in a series of processes and then it transfers ammonia back again to an ammonia-water mixture in another series of processes. The ammonia transfers involve heat absorptions and heat rejections that have as an effect the transfer of heat from a low temperature reservoir to a high temperature reservoir. The aforementioned multidimensional graph was built with equilibrium data of the ammonia-water and ammonia-butane binary systems for a 4 bar pressure and a 240 K to 350 K temperature range. The graphical representation is multidimensional because it shows in one graph values of concentration, temperature, enthalpy, entropy and exergy for ammonia-water mixtures and ammonia-butane mixtures. The thermodynamic states of all the process currents present in the cycle are showed in the graph, as well as are the different thermodynamic processes of the cycle. The exergy destruction rate of each device is clearly represented. The usefulness of this graph is similar to that of the T-s graph for a Rankine cycle.

scholarly journals Spruce Bark—A Source of Polyphenolic Compounds: Optimizing the Operating Conditions of Supercritical Carbon Dioxide Extraction

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4049 ◽  
Author(s):  
Petra Strižincová ◽  
Aleš Ház ◽  
Zuzana Burčová ◽  
Jozef Feranc ◽  
František Kreps ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Total Phenolics ◽  
Extraction Process ◽  
Solvent Mixture ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Bark Extract ◽  
Water Mixture ◽  
Spruce Bark ◽  
Phenolics Content

The present study described the optimization of the extraction process with carbon dioxide in supercritical state for obtaining extractives, especially polyphenols from softwood bark, Norway spruce (Picea abies (L.) Karst.). Using a full 23 factorial design of experiments, the effect of varying the working parameters on the yield of extractives was studied for the following ranges: temperature 40–100 °C, pressure 1050–9000 psi (7.2–62 MPa), and concentration of EtOH/water co-solvent mixture 40–96.6%. In addition, total phenolics content and the antioxidant capacity of the spruce bark extract were determined. The optimum operating conditions for the yield of extractives were identified as 73 °C, 6465 psi (44.5 MPa), and 58% EtOH/water cosolvent concentration for a yield of 8.92%. The optimum conditions for achieving a total phenolics content of 13.89 mg gallic acid equivalent (GAE)/g dry extract were determined as: 45 °C, 1050 psi (7.2 MPa), and 96.6% EtOH/water mixture.

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