Design and Analysis of Ejector Powerplant System

2013 ◽  
Author(s):  
Menandro S. Berana ◽  
Edward T. Bermido
Keyword(s):  
High Pressure ◽  
Ambient Temperature ◽  
Waste Heat ◽  
Temperature Drop ◽  
Working Fluid ◽  
Low Grade ◽  
Heat Sources ◽  
Two Phase ◽  
Evaporator Temperature ◽  
Working Fluids

An ejector is a device with no moving components and is made up of four main parts: converging-diverging nozzle, suction chamber, mixing section and diffuser. It has become popular in refrigeration system as it gives the advantage of recovering expansion energy from high pressure difference into compression energy. In this study, the potential use of ejector in powerplants that use low-grade or low temperature heat sources was conceptualized and analytically investigated. A novel combination of the ejector and the organic Rankine cycle (ORC) was proposed. The driving fluid in the ejector of the proposed powerplant cycle is the high-pressure liquid in the separator that is just circulated back to the evaporator in the ORC. Further increase in turbine temperature drop (TTD), which can increase the power output and efficiency of the plant, can be achieved through expansion, mixing and recompression processes in the ejector. Ocean thermal energy conversion (OTEC), solar-boosted OTEC (SOTEC), solar-thermal, waste-heat driven, biomass and geothermal powerplants were considered in the analysis. Mathematical models in our previous studies were developed and used to calculate for nozzle and ejector parameters. The geometric profile of the ejector for optimization with categorized heat sources was determined. Isentropic, internally reversible, and irreversible two-phase nozzle expansions were analyzed. Two-phase flow calculations were continued in the mixing section. It was assumed that the constant-pressure mixing of the primary and secondary fluids occur at the hypothetical throat inside the constant-area section. Calculation for shock wave in the mixing section was also done. The diffuser was analyzed in a similar manner with the nozzle. Calculation for other components and plant efficiencies was finally conducted. Ammonia and propane which are both natural working fluids were used in the analysis. Evaporator temperature range from 293.15 K to 393.15 K and condenser and ambient temperatures range from 283.15 K to 308.15 K were used in the analysis. The lowest ambient temperature of 283.15 K was used for the OTEC and SOTEC powerplants. It was shown that ammonia and propane can operate up to 11 K and 12 K below the ambient temperature, respectively. Ejector efficiency ranged from 90 to 95% for both working fluids. The maximum efficiencies of the ejector powerplant were 19.2% for ammonia and 14.9% for propane, compared to 11.7% and 9.8% of the conventional ORC. It was analytically determined that the efficiency of the ejector powerplant is higher than that of the ORC powerplant for the same working fluid and conditions of the evaporator, condenser and the ambient.

Second Law Analysis and Optimization of Organic Rankine Cycle

2006 ◽  
Author(s):  
C. Somayaji ◽  
P. J. Mago ◽  
L. M. Chamra
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Second Law ◽  
Low Grade ◽  
Heat Sources ◽  
Working Fluids ◽  
Second Law Analysis

This paper presents a second law analysis and optimization for the use of Organic Rankine Cycle “ORC” to convert waste energy to power from low grade heat sources. The working fluids used in this study are organic substances which have a low boiling point and a low latent heat for using low grade waste heat sources. The organic working fluids under investigation are R134a and R113 and their results are compared with those of ammonia and water under similar operating conditions. A combined first and second law analysis is performed by varying some system operating parameters at various reference temperatures. Some of the results show that the efficiency of ORC is typically below 20% depending on the temperatures and matched working fluid. In addition, it has been found that organic working fluids are more suited for heat recovery than water for low temperature applications, which justifies the use of organic working fluids at the lower waste source temperatures.

Converting Low-Grade Heat Into Power Using a Supercritical Rankine Cycle With Zeotropic Mixture Working Fluid

2010 ◽  
Author(s):  
Huijuan Chen ◽  
D. Yogi Goswami ◽  
Muhammad M. Rahman ◽  
Elias K. Stefanakos
Keyword(s):  
Rankine Cycle ◽  
Phase Region ◽  
Working Fluid ◽  
Condensation Process ◽  
Heating Process ◽  
Low Grade ◽  
Two Phase ◽  
Working Fluids ◽  
Zeotropic Mixture ◽  
Low Grade Heat

A supercritical Rankine cycle using zeotropic mixture working fluids for the conversion of low-grade heat into power is proposed and analyzed in this paper. A supercritical Rankine cycle does not go through two-phase region during the heating process. By adopting zeotropic mixtures as the working fluids, the condensation process happens non-isothermally. Both of the features create a potential in reducing the irreversibility and improving the system efficiency. A comparative study between an organic Rankine cycle and the proposed supercritical Rankine cycle shows that the proposed cycle improves the cycle thermal efficiency, exergy efficiency of the heating and the condensation processes, and the system overall efficiency.

scholarly journals A Simple Method of Finding New Dry and Isentropic Working Fluids for Organic Rankine Cycle

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 480 ◽  
Author(s):  
Gábor Györke ◽  
Axel Groniewsky ◽  
Attila Imre
Keyword(s):  
Low Temperature ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Electricity Production ◽  
Working Fluid ◽  
Heat Sources ◽  
Simple Method ◽  
Working Fluids ◽  
Temperature Heat

One of the most crucial challenges of sustainable development is the use of low-temperature heat sources (60–200 °C), such as thermal solar, geothermal, biomass, or waste heat, for electricity production. Since conventional water-based thermodynamic cycles are not suitable in this temperature range or at least operate with very low efficiency, other working fluids need to be applied. Organic Rankine Cycle (ORC) uses organic working fluids, which results in higher thermal efficiency for low-temperature heat sources. Traditionally, new working fluids are found using a trial-and-error procedure through experience among chemically similar materials. This approach, however, carries a high risk of excluding the ideal working fluid. Therefore, a new method and a simple rule of thumb—based on a correlation related to molar isochoric specific heat capacity of saturated vapor states—were developed. With the application of this thumb rule, novel isentropic and dry working fluids can be found applicable for given low-temperature heat sources. Additionally, the importance of molar quantities—usually ignored by energy engineers—was demonstrated.

Supercritical Fluids and Their Applications in Power Generation

2021 ◽  
pp. 566-599
Author(s):  
Huijuan Chen ◽  
Ricardo Vasquez Padilla ◽  
Saeb Besarati
Keyword(s):  
Power Generation ◽  
Supercritical Fluids ◽  
Waste Heat ◽  
Electrical Power ◽  
Rankine Cycle ◽  
Low Grade ◽  
Heat Sources ◽  
Working Fluids ◽  
Low Grade Heat ◽  
Selection Of

Supercritical fluids have been studied and used as the working fluids in power generation system for both high- and low-grade heat conversions. Low-grade heat sources, typically defined as below 300 ºC, are abundantly available as industrial waste heat, solar thermal, and geothermal, to name a few. However, they are under-exploited for power conversion because of the low conversion efficiency. Technologies that allow the efficient conversion of low-grade heat into mechanical or electrical power are very important to develop. First part of this chapter investigates the potential of supercritical Rankine cycles in the conversion of low-grade heat to power, while the second part discusses supercritical fluids used in higher grade heat conversion system. The selection of supercritical working fluids for a supercritical Rankine cycle is of key importance. This chapter discusses supercritical fluids fundamentals, selection of supercritical working fluids for different heat sources, and the current research, development, and commercial status of supercritical power generation systems.

scholarly journals Experimental Study and Optimization of the Organic Rankine Cycle with Pure NovecTM649 and Zeotropic Mixture NovecTM649/HFE7000 as Working Fluid

2019 ◽  
Vol 9 (9) ◽  
pp. 1865 ◽  
Author(s):  
Quentin Blondel ◽  
Nicolas Tauveron ◽  
Nadia Caney ◽  
Nicolas Voeltzel
Keyword(s):  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Mass Composition ◽  
Low Grade ◽  
Working Fluids ◽  
Replacement Fluid ◽  
Pure Fluid ◽  
Zeotropic Mixture

The Organic Rankine Cycle (ORC) is widely used in industry to recover low-grade heat. Recently, some research on the ORC has focused on micro power production with new low global warming potential (GWP) replacement working fluids. However, few experimental tests have investigated the real performance level of this system in comparison with the ORC using classical fluids. This study concerns the experimental analysis and comparison of a compact (0.25 m3) Organic Rankine Cycle installation using as working fluids the NovecTM649 pure fluid and a zeotropic mixture composed of 80% NovecTM649 and 20% HFE7000 (mass composition) for low-grade waste heat conversion to produce low power. The purpose of this experimental test bench is to study replacement fluids and characterize them as possible replacement fluid candidates for an existing ORC system. The ORC performance with the pure fluid, which is the media specifically designed for this conversion system, shows good results as a replacement fluid in comparison with the ORC literature. The use of the mixture leads to a 10% increase in the global performance of the installation. Concerning the expansion component, an axial micro-turbine, its performance is only slightly affected by the use of the mixture. These results show that zeotropic mixtures can be used as an adjustment parameter for a given ORC installation and thus allow for the best use of the heat source available to produce electricity.

Ceramic Flat Plate Evaporator for Loop Heat Pipe Cooling of Electronics

2005 ◽  
Author(s):  
Walter Zimbeck ◽  
Jared Chaney ◽  
Patricio Espinoza ◽  
Edward Kroliczek ◽  
David C. Bugby ◽  
...  
Keyword(s):  
Flat Plate ◽  
Heat Pipe ◽  
Temperature Drop ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Heat Sources ◽  
Two Phase ◽  
Low Thermal Expansion ◽  
Phase Loop ◽  
Cooling Of Electronics

Two-phase loops are extremely efficient devices for passively transporting heat over long distances with low temperature drop. The heat acquisition component of a two-phase loop, the evaporator, is commonly made from conventional metal materials (aluminum, copper, etc.) and has cylindrical geometry. Neither characteristic is optimally suited for close integration to common electronic or photonic heat sources, which generally have flat interfaces and are constructed from low thermal expansion coefficient (CTE) semiconductor materials. This paper describes the development of a ceramic flat plate evaporator for cooling processor chips in network computers used onboard Navy submarines. The unique requirements of submarines give added motivation for the advantages offered by two-phase loops. The ceramic flat plate evaporator is constructed of low CTE, high thermal conductivity material and thus enables a low thermal resistance interface between the heat source and the working fluid of the loop heat pipe. Alumina and aluminum nitride flat plate evaporators were integrated into a water-based two-phase loop and thermally tested to a heat flux of 30 W/cm2.

scholarly journals Organic Rankine Cycle Optimization Performance Analysis Based on Super-Heater Pressure: Comparison of Working Fluids

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2548
Author(s):  
Ana Fernández-Guillamón ◽  
Ángel Molina-García ◽  
Francisco Vera-García ◽  
José A. Almendros-Ibáñez
Keyword(s):  
Waste Heat ◽  
Saturation Pressure ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade ◽  
Ambient Conditions ◽  
Working Fluids ◽  
Super Heater ◽  
Condensing Pressure

The organic Rankine cycle (ORC) is widely accepted to produce electricity from low-grade thermal heat sources. In fact, it is a developed technology for waste-heat to electricity conversions. In this paper, an ORC made up of super-heater, turbine, regenerator, condenser, pump, economizer and evaporator is considered. An optimization model to obtain the maximum performance of such ORC, depending on the super-heater pressure, is proposed and assessed, in order to find possible new working fluids that are less pollutant with similar behavior to those traditionally used. The different super-heater pressures under analysis lie in between the condenser pressure and 80% of the critical pressure of each working fluid, taking 100 values uniformly distributed. The system and optimization algorithm have been simulated in Matlab with the CoolProp library. Results show that the twelve working fluids can be categorized into four main groups, depending on the saturation pressure at ambient conditions (condenser pressure), observing that the fluids belonging to Group 1, which corresponds with the lower condensing pressure (around 100 kPa), provide the highest thermal efficiency, with values around η=23−25%. Moreover, it is also seen that R123 can be a good candidate to substitute R141B and R11; R114 can replace R236EA and R245FA; and both R1234ZE and R1234YF have similar behavior to R134A.

Working Fluid Selection and Technoeconomic Optimization of a Turbocompression Cooling System

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Derek Young ◽  
Spencer C. Gibson ◽  
Todd M. Bandhauer
Keyword(s):  
Heat Exchanger ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cooling System ◽  
Payback Period ◽  
Working Fluid ◽  
Low Grade ◽  
Diesel Generator ◽  
Working Fluids

Abstract Low grade waste heat recovery presents an opportunity to utilize typically wasted energy to reduce overall energy consumption and improve system efficiencies. In this work, the technoeconomic performance of a turbocompression cooling system (TCCS) driven by low grade waste heat in the engine coolant of a large marine diesel generator set is investigated. Five different working fluids were examined to better understand the effects of fluid characteristics on system performance: R134a, R245fa, R1234ze(E), R152a, and R600a. A coupled thermodynamic, heat exchanger, and economic simulation was developed to calculate the simple payback period of the waste heat recovery system, which was minimized using a search and find optimization routine with heat exchanger effectiveness as the optimization parameter. A sensitivity study was performed to understand which heat exchanger effectiveness had the largest impact on payback period. Of the five working fluids examined, a TCCS with R152a as the working fluid had the lowest payback period of 1.46 years with an initial investment of $181,846. The R152a system was most sensitive to the two-phase region of the power cycle condenser. The R1234ze(E) system provided the largest return on investment over a ten year lifetime of $1,399,666.

scholarly journals System Design and Application of Supercritical and Transcritical CO2 Power Cycles: A Review

2021 ◽  
Vol 9 ◽  
Author(s):  
Enhua Wang ◽  
Ningjian Peng ◽  
Mengru Zhang
Keyword(s):  
Power Systems ◽  
Environmentally Friendly ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade ◽  
Heat Sources ◽  
Technological Advancement ◽  
Working Fluids ◽  
Power Cycles ◽  
Low Grade Heat

Improving energy efficiency and reducing carbon emissions are crucial for the technological advancement of power systems. Various carbon dioxide (CO2) power cycles have been proposed for various applications. For high-temperature heat sources, the CO2 power system is more efficient than the ultra-supercritical steam Rankine cycle. As a working fluid, CO2 exhibits environmentally friendly properties. CO2 can be used as an alternative to organic working fluids in small- and medium-sized power systems for low-grade heat sources. In this paper, the main configurations and performance characteristics of CO2 power systems are reviewed. Furthermore, recent system improvements of CO2 power cycles, including supercritical Brayton cycles and transcritical Rankine cycles, are presented. Applications of combined systems and their economic performance are discussed. Finally, the challenges and potential future developments of CO2 power cycles are discussed. CO2 power cycles have their advantages in various applications. As working fluids must exhibit environmentally-friendly properties, CO2 power cycles provide an alternative for power generation, especially for low-grade heat sources.

Supercritical Fluids and Their Applications in Power Generation

2017 ◽  
pp. 369-402
Author(s):  
Huijuan Chen ◽  
Ricardo Vasquez Padilla ◽  
Saeb Besarati
Keyword(s):  
Power Generation ◽  
Supercritical Fluids ◽  
Waste Heat ◽  
Electrical Power ◽  
Rankine Cycle ◽  
Low Grade ◽  
Heat Sources ◽  
Working Fluids ◽  
Low Grade Heat ◽  
Selection Of

Supercritical fluids have been studied and used as the working fluids in power generation system for both high- and low-grade heat conversions. Low-grade heat sources, typically defined as below 300 ºC, are abundantly available as industrial waste heat, solar thermal, and geothermal, to name a few. However, they are under-exploited for power conversion because of the low conversion efficiency. Technologies that allow the efficient conversion of low-grade heat into mechanical or electrical power are very important to develop. First part of this chapter investigates the potential of supercritical Rankine cycles in the conversion of low-grade heat to power, while the second part discusses supercritical fluids used in higher grade heat conversion system. The selection of supercritical working fluids for a supercritical Rankine cycle is of key importance. This chapter discusses supercritical fluids fundamentals, selection of supercritical working fluids for different heat sources, and the current research, development, and commercial status of supercritical power generation systems.

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