An Example of the Manipulation of Effective Vapor Pressure Curves by Thermodynamic Cycles

1988 ◽  
Vol 110 (4) ◽  
pp. 647-651 ◽  
Author(s):  
R. Radermacher
Keyword(s):  
Vapor Pressure ◽  
Rankine Cycle ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Large Temperature ◽  
Pressure Curve ◽  
Two Stage ◽  
Fluid Mixture ◽  
Thermodynamic Cycles ◽  
Vapor Pressure Curve

The performance of a two-stage Rankine cycle employing a working fluid mixture and solution circuits has been computed with reference to heat pump applications. Its performance is compared to the single-stage version of this cycle and one operating with pure refrigerants. It is found that the two-stage cycle operates along an “effective” vapor pressure curve of very flat slope, resulting in pressure ratios that are reduced to about one third compared to conventional cycles. For large temperature differences between heat sink and source the Coefficient of Performance (COP) can be increased by up to 50 percent.

Vapor pressure curve determination of α-lipoic acid raw material and capsules by dynamic thermogravimetric method

2012 ◽  
Vol 544 ◽  
pp. 95-98 ◽  
Author(s):  
Alyne da Silva Portela ◽  
Maria das Graças Almeida ◽  
Ana Paula Barreto Gomes ◽  
Lidiane Pinto Correia ◽  
Paulo Cesar Dantas da Silva ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Lipoic Acid ◽  
Raw Material ◽  
Pressure Curve ◽  
Thermogravimetric Method ◽  
Vapor Pressure Curve ◽  
Curve Determination

The Vapor-Pressure Curve of Helium between 4.2°K and 4.8°K

1954 ◽  
Vol 93 (1) ◽  
pp. 45-46 ◽  
Author(s):  
R. D. Worley ◽  
M. W. Zemansky ◽  
H. A. Boorse
Keyword(s):  
Vapor Pressure ◽  
Pressure Curve ◽  
Vapor Pressure Curve

scholarly journals Performance comparison of the solar-driven supercritical organic Rankine cycle coupled with the vapour-compression refrigeration cycle

Clean Energy ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 476-491
Author(s):  
Yunis Khan ◽  
Radhey Shyam Mishra
Keyword(s):  
Thermal Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Coefficient Of Performance ◽  
Solar Irradiation ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Exergy Destruction ◽  
Cogeneration System ◽  
Vapour Compression

Abstract In this study, a parametric analysis was performed of a supercritical organic Rankine cycle driven by solar parabolic trough collectors (PTCs) coupled with a vapour-compression refrigeration cycle simultaneously for cooling and power production. Thermal efficiency, exergy efficiency, exergy destruction and the coefficient of performance of the cogeneration system were considered to be performance parameters. A computer program was developed in engineering equation-solver software for analysis. Influences of the PTC design parameters (solar irradiation, solar-beam incidence angle and velocity of the heat-transfer fluid in the absorber tube), turbine inlet pressure, condenser and evaporator temperature on system performance were discussed. Furthermore, the performance of the cogeneration system was also compared with and without PTCs. It was concluded that it was necessary to design the PTCs carefully in order to achieve better cogeneration performance. The highest values of exergy efficiency, thermal efficiency and exergy destruction of the cogeneration system were 92.9%, 51.13% and 1437 kW, respectively, at 0.95 kW/m2 of solar irradiation based on working fluid R227ea, but the highest coefficient of performance was found to be 2.278 on the basis of working fluid R134a. It was also obtained from the results that PTCs accounted for 76.32% of the total exergy destruction of the overall system and the cogeneration system performed well without considering solar performance.

Innovative Research in the Organic Rankine Cycle

Impact ◽  
2020 ◽  
Vol 2020 (6) ◽  
pp. 76-78
Author(s):  
Tzu-Chen Hung ◽  
Yong-Qiang Feng
Keyword(s):  
Phase Change ◽  
Mechanical Energy ◽  
Heat Engine ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Vapour Phase ◽  
Working Fluid ◽  
Low Grade ◽  
Initial State ◽  
Thermodynamic Cycles

Thermodynamic cycles consist of a sequence of thermodynamic processes involving the transfer of heat and work into and then out of a system. Variables, such as pressure and temperature, eventually return the system to its initial state. During the process of passing through the system, the working fluid converts heat and disposes of any remaining heat, making the cycle act as a heat engine, where heat or thermal energy is converted into mechanical energy. Thermodynamic cycles are an efficient means of producing energy and one of the most well-known examples is a Rankine cycle. From there, scientists have developed the organic Rankine cycle (ORC), which uses fluid with a liquid to vapour phase change that occurs at a lower temperature than the water to steam phase change. Dr Tzu-Chen Hung and Dr Yong-Qiang Feng, who are based at both the Department of Mechanical Engineering, National Taipei University in Taiwan, and the School of Energy and Power Engineering, Jiangsu University in China, are carrying out work that seeks to design and build improved ORC systems which can be used for low-grade heat to power conversion.

Phase Behavior and Its Effects on Reactions in Liquid and Supercritical Carbon Dioxide

2004 ◽  
Author(s):  
Lynnette A. Blanchard ◽  
Gang Xu
Keyword(s):  
Carbon Dioxide ◽  
Melting Point ◽  
Vapor Pressure ◽  
Phase Behavior ◽  
Critical Point ◽  
Pressure Curve ◽  
Light Component ◽  
Vapor Pressure Curve ◽  
Solid Liquid ◽  
Liquid Vapor

Carbon dioxide, either as an expanded liquid or as a supercritical fluid, may be a viable replacement for a variety of conventional organic solvents in reaction systems. Numerous studies have shown that many reactions can be conducted in liquid or supercritical CO2 (sc CO2) and, in some cases, rates and selectivities can be achieved that are greater than those possible in normal liquid- or gas-phase reactions (other chapters in this book; Noyori, 1999; Savage et al., 1995). Nonetheless, commercial exploitation of this technology has been limited. One factor that contributes to this reluctance is the extremely complex phase behavior that can be encountered with high-pressure multicomponent systems. Even for simple binary systems, one can observe multiple fluid phases, as shown in Figure 1.1. The figure shows the pressure–temperature (PT) projection of the phase diagram of a binary system, where the vapor pressure curve of the light component (e.g., CO2) is the solid line shown at temperatures below TB. It is terminated by its critical point, which is shown as a solid circle. The sublimation curve, melting curve, and vapor pressure curve of the pure component 2 (say, a reactant that is a solid at ambient conditions) are the solid lines shown at higher temperatures on the right side of the diagram; that is, the triple point of this compound is above TE. The solid might experience a significant melting point depression when exposed to CO2 pressure [the dashed–dotted solid/liquid/vapor (SLV) line, which terminates in an upper critical end point (UCEP)]. For instance, naphthalene melts at 60.1 °C under CO2 pressure (i.e., one might observe a three-phase solid/liquid/vapor system), even though the normal melting point is 80.5 °C (McHugh and Yogan, 1984). To complicate things even further, there will be a region close to the critical point of pure CO2 where one will observe three phases as well, as indicated by the dashed–dotted SLV line that terminates at the lower critical end point (LCEP). The dotted line connecting the critical point of the light component and the LCEP is a vapor/liquid critical point locus.

Working Fluid and Parametric Optimization of a Two-Stage ORC Utilizing LNG Cold Energy and Low Grade Heat of Different Temperatures

2017 ◽  
Author(s):  
Zhixin Sun ◽  
Shujia Wang ◽  
Fuquan Xu ◽  
Tielong Wang
Keyword(s):  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Cycle Performance ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Low Grade ◽  
Two Stage ◽  
Cold Energy ◽  
Low Grade Heat

Natural gas is considered as a green fuel due to its low environmental impact. LNG contains a large amount of cold exergy and must be regasified before further utilization. ORC (Organic Rankine Cycle) has been proven to be a promising solution for both low grade heat utilization and LNG cold exergy recovery. Due to the great temperature difference between the heat source and LNG, the efficiency of one-stage ORC is relatively small. Hence, some researchers move forward to a two-stage Rankine cycle. Working fluid plays a quite important role in the cycle performance. Working fluid selection of a two-stage ORC is much more challenging than that of a single-stage ORC. In this paper, a two-stage ORC is studied. Heat source temperatures of 100,150 and 200°C are investigated. 20 substances are selected as potential candidates for both the high and low Rankine cycles. The evaporating, condensing and turbine inlet temperatures of both Rankine cycles are optimized by PSO (Particle Swarm Optimization). The results show that the best combination for heat source temperature of 100°C is R161/R218 with the maximum exergy efficiency of 35.27%. The best combination for 150°C is R161/RC318 with the maximum efficiency of 37.84% and ammonia/ammonia with the maximum efficiency of 39.15% for 200°C. Fluids with intermediate critical temperature, lower triple point temperature and lower normal boiling temperature are good candidates.

A Transcritical CO2 Rankine Cycle With LNG Cold Energy Utilization and Liquefaction of CO2 in Gas Turbine Emission

2008 ◽  
Author(s):  
Meibin Huang ◽  
Wensheng Lin ◽  
Hongming He ◽  
Anzhong Gu
Keyword(s):  
Gas Turbine ◽  
Rankine Cycle ◽  
Energy Utilization ◽  
Working Fluid ◽  
Large Temperature ◽  
Specific Work ◽  
Environment Friendly ◽  
Cold Energy ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

A novel transcritical Rankine cycle is presented in this paper. This cycle adopts CO2 as its working fluid, with exhaust from a gas turbine as its heat source and LNG as its cold sink. With CO2 working transcritically, large temperature difference for the Rankine cycle is realized. Moreover, the CO2 in the gas turbine exhaust is further cooled and liquefied by LNG after transferring heat to the Rankine cycle. In this way, not only the cold energy is utilized, but also a large part of the CO2 from burning of the vaporized LNG is recovered. In this paper, the system performance of this transcritical cycle is calculated. The influences of the highest cycle temperature and pressure to system specific work, exergy efficiency and liquefied CO2 mass flow rate are analyzed. The exergy loss in each of the heat exchangers is also discussed. It turns out that this kind of CO2 cycle is energy-conservative and environment-friendly.

scholarly journals Exergy and Exergoeconomic Analysis of a Cogeneration Hybrid Solar Organic Rankine Cycle with Ejector

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 702
Author(s):  
Bourhan Tashtoush ◽  
Tatiana Morosuk ◽  
Jigar Chudasama
Keyword(s):  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Refrigeration System ◽  
Entrainment Ratio ◽  
Temperature And Pressure

Solar energy is utilized in a combined ejector refrigeration system with an organic Rankine cycle (ORC) to produce a cooling effect and generate electrical power. This study aims at increasing the utilized share of the collected solar thermal energy by inserting an ORC into the system. As the ejector refrigeration cycle reaches its maximum coefficient of performance (COP), the ORC starts working and generating electrical power. This electricity is used to run the circulating pumps and the control system, which makes the system autonomous. For the ejector refrigeration system, R134a refrigerant is selected as the working fluid for its performance characteristics and environmentally friendly nature. The COP of 0.53 was obtained for the ejector refrigeration cycle. The combined cycle of the solar ejector refrigeration and ORC is modeled in EBSILON Professional. Different parameters like generator temperature and pressure, condenser temperature and pressure, and entrainment ratio are studied, and the effect of these parameters on the cycle COP is investigated. Exergy, economic, and exergoeconomic analyses of the hybrid system are carried out to identify the thermodynamic and cost inefficiencies present in various components of the system.

Ultraviolet and infrared spectrum of C6H2 revisited and vapor pressure curve in Titan's atmosphere

2003 ◽  
Vol 51 (1) ◽  
pp. 9-17 ◽  
Author(s):  
F. Shindo ◽  
Y. Benilan ◽  
J.-C. Guillemin ◽  
P. Chaquin ◽  
A. Jolly ◽  
...  
Keyword(s):  
Infrared Spectrum ◽  
Vapor Pressure ◽  
Pressure Curve ◽  
Vapor Pressure Curve
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