Analysis Of Organic Rankine Cycle Research Articles

Exergy Analysis of Organic Rankine Cycle and Electric Turbo Compounding for Waste Heat Recovery

With such tough legislation on current emission standards, car manufacturers are focusing on increasing the efficiency of their engines with the development of advance waste heat recover (WHR) technology. Organic Rankine Cycle (ORC) and Electric Turbo Compounding (ETC) system have a good potential to be used as exhaust energy recovery. This paper compares the exergy availability and losses between the ORC and the ETC. In this particular study, exhaust data from the Proton 1.6L CamPro CFE turbocharged engine was used. This particular engine already has a main turbocharger, making the added WHR as a secondary recovery system to further increase the engine efficiency. Both systems are coupled to a 1 kW electric generator for ease of comparisons. At first the available exergy is calculated for both WHR technologies. Exergy losses from rotating the generator are analysed to finally determine the thermal efficiency of the overall system. Exergy calculation is simplified to only account for chemical and physical exergy since kinetic and potential energy are negligible in comparison. Available exergy for ORC was significantly high which went up to 12.5 kW with the exergy losses recorded at 9.7 kW. The ETC achieved only 5 kW but had a small loss at 8x10-3 kW. Average thermal efficiency of the ORC systems was 10.7% compared to ETC which was 58.7%. It can be concluded that the complexity of the ORC system contributes to its downfall where multiple components increase its exergy losses compared to the simplistic design of an ETC.

Thermodynamic analysis of organic Rankine cycle with Hydrofluoroethers as working fluids

This paper presents the analysis of organic Rankine cycle (ORC) using hydrofluoroethers (HFEs) such as HFE7000, HFE7100 and HFE7500 as working fluids under external conditions. HFE's has been chosen over chlorofluorocarbons (CFC's) and hydro chlorofluorocarbons (HCFC's) as it is environmentally friendly. Both the CFC's and the HCFC's possess ozone depletion potential (ODP), while the hydrofluorocarbons (HFC's) have relatively significant global warming potential (GWP). The HFE's that have excellent thermophysical properties and low toxicity can be recommended as a long term solution to the environmental issues. The HFE's have zero ODP and very low GWP compared to the CFC's, HCFC's and HFC's. A thermodynamic model has been developed using Engineering Equation Solver (EES) software to simulate the system under steady state conditions. Parametric analysis is conducted to examine the effects of some thermodynamic parameters on the system performance using different working fluids. When turbine inlet temperature was varied from 70°C to 110 °C keeping condensation temperature fixed at 28 °C, HFE7000 produces the maximum thermodynamic efficiency and performs better in view of the net work output under the given working conditions. However, when evaporation pressure was kept constant at 1.2 bar and condensation temperature was varied from 20°C to 30 °C, HFE7500 produced the maximum efficiency of 12.3% in comparison with 7.6% for HFE7100 and 4.1% for HFE7000. The work demonstrates the use of hydrofluoroethers as working fluid in ORC.

Alternative approach in performance analysis of organic rankine cycle (ORC)

In this study, artificial neural networks (ANNs) and adaptive neuro‐fuzzy (ANFIS) have been used for performance analysis of organic rankine cycle (ORC) using refrigerants R123, R125, R227, R365mfc, SES36. It is well known that the steam generator temperature, condenser temperature, subcooling temperature, and superheating temperature affect the efficiency ratio of ORC. Therefore, efficiency ratio is forecasted depending on variable system parameters values. The results of ANN are compared with ANFIS in which the same data sets are used. Furthermore, new formulations derived from ANN for five refrigerants are presented for the determination of the efficiency ratio. The R2 values obtained from the networks were 0.99917, 0.99670, 0.99870, 0.99928, and 0.99911 for the R123, R125, R227, R365mfc, SES36 respectively which is very satisfactory. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 254–259, 2019

Emergy analysis of Organic Rankine Cycle (ORC) for waste heat power generation

Abstract Converting the low grade energy into electric energy can effectively reduce the environmental pollution and improve the efficiency of energy utilization. Evaluating this kind of energy conversion is important. The sustainability evaluation of Organic Rankine Cycle (ORC) for the waste heat power generation is carried out using emergy analysis and life cycle method. The relationship to determine the transformity of the waste heat is presented. In the life cycle boundary, working fluid R134a in the ORC is firstly analyzed by emergy analysis. All the input flows including renewable resources, non-renewable resources and purchased investments in the whole life cycle of electricity produced by the ORC system have been calculated. The results show that the emergy yield ratio (EYR) and emergy index of sustainability (ESI) of an ORC are 197.52 and 3.97, respectively. The sustainability of the ORC system is less than that of wind, hydro and geothermal power plant, but much greater than that of fossil fuel power plants. The emergy proportion of the working fluid R134a accounts for 13.3% to the total input flows in the construction phase. The working fluid in an ORC system cannot be neglected in the life cycle analysis.

선박용 엔진의 배기 열을 회수하기 위한 유기랭킨 사이클의 이론적 해석

선박용 엔진의 배기 열을 회수하기 위한 유기랭킨 사이클의 이론적 해석

Thermodynamic analysis of organic Rankine cycle used for flue gases from biogas combustion

This study elaborates an investigation on organic Rankine cycle (ORC) for integration with a sewage plant for generation of power and district heating purposes. Flue gases from combustion of biogas is considered as heat source. Initially, design constraints of the cycle i.e. pump exit temperature, source exit temperature, cooling fluid exit temperature, and flue gases exit temperature are applied to check the ORC applicability. Furthermore, fifteen sets of working conditions with combinations of evaporation pressure, source temperature, and pinch point condition are passed through a step by step energetic and exergetic analysis. Seven best set of working conditions are shortlisted to examine the thermal efficiency of the cycle for combined heat and power (CHP) generation. In addition, the research also highlights the importance of biogas technology with respect to environment. The results show that the maximum work output of 156.4 kW is produced at source temperature of 345 °C, evaporation pressure of 36 bar, and pinch point of 5 °C at evaporator and 10 °C at condenser. This research demonstrates that biogas-fired ORC systems depicts an efficient solution for domestic scale power generation applications in rural areas.

Parametric analysis of organic Rankine cycle based on a radial turbine for low-grade waste heat recovery

Organic Rankine cycle (ORC) is one of the promising technologies to convert low-grade waste heat into electricity. This study comprehensively investigates the thermodynamic performance of ORC system and the aerodynamic characteristics of radial turbine. An optimized coupling model for the ORC with a radial turbine is developed, and the particle swarm optimization algorithm is applied to maximize the turbine efficiency dynamically. The model is used to evaluate the effect of heat source temperature on the cycle performance and parameter selection for turbine design optimization. The results show that optimal turbine efficiency can be achieved within the considered heat source outlet temperature range, as high pressure ratio and high mass flow rate can both degrade the turbine efficiency. Among the four studied organic fluids, the ORCs using R123 and R245fa can achieve desirable cycle performances. For the turbine design, lower degree of reaction is beneficial for turbine efficiency gains. The optimized rotational speed and ratio of wheel diameter are dependent on heat source temperature, while which has almost no effects on velocity ratio, loading coefficient, and flow coefficient. The reasonable ranges of partial turbine design parameters are also proposed in this work.

Thermodynamic Analysis of Organic Rankine Cycle with Hydrofluoroethers as Working Fluids

Abstract This paper presents an analysis of organic Rankine cycle (ORC) using hydrofluoroethers including HFE7000, HFE7100 and HFE7500 as working fluids under constant external conditions. A computer program has been developed to parametrically compare the first and second law efficiencies, power output, turbine size factor with increase in turbine entry temperature. The results show that HFE7000 produces the maximum thermodynamic efficiencies and performs better in view of the net power output under the given working conditions. Moreover, HFE7000 has the lowest turbine size factor comparing with HFE7100 and HFE7500. Therefore, HFE7000 can be recommended to be used as working fluid in ORC to convert low-grade heat into power.

Energy, anergy and exergy analysis of organic rankine cycle for a residential apartment using solar energy based on aspen plus

Energy, anergy and exergy analysis of organic rankine cycle for a residential apartment using solar energy based on aspen plus

Energy and Exergy Analysis of Organic Rankine Cycle Using Alternative Working Fluids

The present study is based on parametric investigation in terms of thermal efficiency, exergetic efficiency and exergy destruction with the help mathematical modeling on different ORC models using different fluids. The Thermal efficiency of ORC model of Saturated, Trilateral is compared by using working fluids such as (HFO-1234yf,HFC-134a,HFC-245fa,Ethanol,Iso-pentane by varying expander inlet temperature (30- 160⁰C),at fixed condensation temperature(30⁰C) assuming fixed expander isentropic efficiency ( =0.75) and fixed isentropic pump efficiency( =0.60). The Thermal efficiency as well as exergetic efficiency has been observed best for theHFO-1234yf and found nearly close with HFC-134a. HFO-1234yf has good potential for working fluid for ORC application for low to medium temperature. It has zero global warming potential (GWP), zero Ozone layer depletion (ODP) and very Low evaporation Temperature. This paper provides a basis to compare the thermal and exergetic efficiency for various working fluids and exergy destruction in various component such as Expander, Evaporator,Condenser,Pump for saturated and Trilateral cycle when used with R-1234yf as working substance.

Performance analysis of organic Rankine cycles using R600/R601a mixtures with liquid-separated condensation

Organic Rankine cycle (ORC) is a promising technology for power generation from medium to low temperature heat sources (<350°C). Although a zeotropic mixture can improve ORC efficiency, its large condenser heat transfer area is a crucial factor that impedes the broad application of ORCs using zeotropic mixtures. The liquid-separated condensation method is the process of separating the condensed fluid from the two-phase flow during condensation. This method has potential to effectively reduce the condenser heat transfer area of an ORC using a zeotropic mixture by increasing the condensation heat transfer coefficient and reducing the pressure drop. This study introduced the liquid-separated condensation into ORCs using R600/R601a mixtures. The effects of vapor quality at the liquid-separated unit inlet (xLSI) on the net power outputs, condensation heat transfer coefficients and heat transfer areas were analyzed. Results show that a xLSI below 0.3 maximizes the average condensation heat transfer coefficient for the R600/R601a mixture. The liquid-separated condensation can increase the average condensation heat transfer coefficient by 23.8% and reduce the condenser heat transfer area by 44.1% compared to the conventional condensation. Although the liquid-separated condensation may slightly reduce the maximized net power output for a low xLSI, the decrease of total heat transfer area is larger than that of the maximized net power output. Thus, the ratio of the total heat transfer area to the net power output can be reduced by 28.3%. The R600/R601a (0.9/0.1) mixture with xLSI=0.3 obtains the lowest electricity generation cost for the R600/R601a mixtures with single-stage liquid-separated condensation.

Parametric-Based Thermodynamic Analysis of Organic Rankine Cycle as Bottoming Cycle for Combined-Cycle Power Plant

In Pakistan, the thermal efficiency of the power plants is low because of a huge share of fuel energy is dumped into the atmosphere as waste heat. The ORC (Organic Rankine Cycle) has been revealed as one of the promising technologies to recover waste heat to enhance the thermal efficiency of the power plant. In current work, ORC is proposed as a second bottoming cycle for existing CCPP (Combined Cycle Power Plant). In order to assess the efficiency of the plant, a thermodynamic model is developed in the ESS (Engineering Equation Solver) software. The developed model is used for parametric analysis to assess the effects of various operating parameters on the system performance. The analysis of results shows that the integration of ORC system with existing CCPP system enhances the overall power output in the range of 150.5-154.58 MW with 0.24-5% enhancement in the efficiency depending on the operating conditions. During the parametric analysis of ORC, it is observed that inlet pressure of the turbine shows a significant effect on the performance of the system as compared to other operating parameters.

Research of efficiency of the organic Rankine cycle on a mathematical model

The object of the study are the organic Rankine cycle. The purpose of research is to evaluate the impact on the net efficiency of the initial and final properties of the cycle at work on a saturated and superheated steam. Investigations were carried out on the basis of a mathematical model, in which the thermodynamic properties of materials are determined on the basis of “REFPROP”. On the basis of the available scientific publications on the use of working fluids in an organic Rankine cycle analysis was selected ozone-safe pentane. A mathematical model has been developed on condition that condenser is used as air cooler which allows the substance to condense at a temperature below 0 °С. Numerical study on the mathematical model shown that net efficiency at work on pentane linearly depends on the condensation temperature and parabolically depends on the initial temperature with the saturated steam. During work at the superheated steam efficiency strongly depends on both the initial temperature and of the initial pressure. With rising initial temperature is necessary to gradually increase the initial pressure under certain conditions.

Off-design performance analysis of organic Rankine cycle using real operation data from a heat source plant

There has been increasing demand for cogeneration power plants, which provides high energy utilization. Research on upgrading power plant performance is also being actively pursued. The organic Rankine cycle (ORC) can operate with mid- and low-temperature heat sources and is suitable for enhancing performance of existing power plants. In this study, an off-design analysis model for the ORC was developed, which is driven by waste heat or residual heat from a combined cycle cogeneration plant. The applied heat sources are the exhaust gas from the heat recovery steam generator (Case 1) and waste heat from a heat storage unit (Case 2). Optimal design points of the ORC were selected based on the design heat source condition of each case. Then, the available ORC power output for each case was predicted using actual long-term plant operation data and a validated off-design analysis model. The ORC capacity of Case 2 was almost two times larger than that of Case 1. The predicted average electricity generation of both cases was less than the design output. The results of this paper reveal the importance of both the prediction of electricity generation using actual plant operation data and the need for optimal ORC system sizing.

Three dimensional optimization of small-scale axial turbine for low temperature heat source driven organic Rankine cycle

Advances in optimization techniques can be used to enhance the performance of turbines in various applications. However, limited work has been reported on using such optimization techniques to develop small-scale turbines for organic Rankine cycles. This paper investigates the use of multi-objective genetic algorithm to optimize the stage geometry of a small-axial subsonic turbine. This optimization is integrated with organic Rankine cycle analysis using wide range of high density organic working fluids like R123, R134a, R141b, R152a, R245fa and isobutane suitable for low temperature heat sources <100°C such as solar energy to achieve the best turbine design and highest organic Rankine cycle efficiency. The isentropic efficiency of the turbine in most of the reported organic Rankine cycle studies was assumed constant, while the current work allows the turbine isentropic efficiency to change (dynamic value) with both operating conditions and working fluids. Three-dimensional computational fluid dynamics analysis and multi-objective genetic algorithm optimization were performed using three-dimensional Reynolds-averaged Navier-Stokes equations with k-omega shear stress transport turbulence model in ANSYSR17-CFX and design exploration for various working fluids. The optimization was carried out using eight design parameters for the turbine stage geometry optimization including stator and rotor number of blades, rotor leading edge beta angle, trailing edge beta angle, stagger angle, throat width, trailing half wedge angle and shroud tip clearance. Results showed that using working fluid R123 for a turbine with mean diameter of 70mm, the maximum isentropic efficiency was about 88% and power output of 6.3kW leading to cycle thermal efficiency of 10.5% showing an enhancement of 14.08% compared to the baseline design. Such results highlight the potential of the 3D optimization technique to improve the organic Rankine cycle performance.

Analysis of organic Rankine cycles using zeotropic mixtures as working fluids under different restrictive conditions

Organic Rankine cycle has been regarded as a reasonable technology to utilize low-temperature geothermal sources. This paper analyzes the internal relation about zeotropic mixture selection under different restrictive conditions. R601a/R600 and R245fa/R600a are selected as typical examples of symmetrical and asymmetric zeotropic mixtures. The fixed condenser bubble temperature, the fixed cooling water temperature rise and the fixed cooling water flow rate are considered as restrictive conditions. Both the basic and the regenerative organic Rankine cycle system are considered as research subjects. The fixed cooling water flow rate is suggested to select the appropriate zeotropic mixture. The results indicate that the performance corves with the fixed condenser bubble temperature of 25°C are significant in zeotropic mixture selection, and these corves reflect the full potential of zeotropic mixtures to improve the net power. The temperature glide decreases the net power with the fixed condenser bubble temperature. However, the opposite phenomenon is found when the fixed cooling water temperature rise or the fixed cooling water flow rate is applied. The application of intermediate heat exchangers may lead to the larger, the smaller or the same net power with different temperature glides and restrictive conditions. However, the cycle efficiency is increased all the time.

Impact of organic Rankine cycle system installation on light duty vehicle considering both positive and negative aspects

This paper presents the analysis of organic Rankine cycle (ORC) based waste heat recovery system. Both the positive and negative effects of ORC system installation on a light duty vehicle were evaluated. Engine exhaust data for a light duty vehicle was used to design an ORC based system. Optimum cycle design suggests that ORC system installation is feasible. Results presented that for the vehicle operation at 100km/h, engine power can be enhanced by 10.88% which is 5.92kW of additional power and at the lower speed of 23.5km/h, the engine power enhancement was 2.34%. ORC component weight data from manufacturers were used to estimate the weight of the designed system. The performance decline due to added weight is calculated. Effects of added back pressure and performance decline due to the part-load operation of ORC unit were also calculated and an overall effect of waste heat recovery system was evaluated. The results then suggested that maximum power enhancement is 5.82% at the vehicle speed of 100km/h instead of previously mentioned 10.88% can be achieved if negative effects are also considered. Furthermore, it was concluded that at speeds lower than 48km/h the waste heat recovery system was not beneficial at all and low-speed operation was in fact not preferable as it results in additional power demand from the engine by 6.39% at 23.5km/h. The vehicles for city driving cycles are not recommended for ORC installation. Another finding revealed that if exhaust heat recovery heat exchanger is designed for maximum heat recovery, at part load operation, the heat exchanger is not suitable to maintain working fluid temperature below the critical temperature of working fluid and minimum exhaust gas temperature at heat exchanger exit.

Parametric design and off-design analysis of organic Rankine cycle (ORC) system

A one-dimensional analysis method has been proposed for the organic Rankine cycle (ORC) system in this paper. The method contains two main parts: a one-dimensional aerodynamic analysis model of the radial-inflow turbine and a performance prediction model of the heat exchanger. Based on the present method, an ORC system for the industrial waste heat recovery is designed and analyzed. The net power output of the ORC system is 534kW, and the thermal efficiency reaches 13.5%. System performance under off-design conditions is simulated and considered. The results show that the inlet temperatures of the heat source and the cooling water have a significant influence on the system. With the increment of the heat source inlet temperature, the mass flow rate of the working fluid, the net power output and the heat utilization ratio of the ORC system increase. While, the system thermal efficiency decreases with increasing cooling water inlet temperature. In order to maintain the condensation pressure at a moderate value, the heat source inlet temperature considered in this analysis should be kept within the range of 443.15–468.15K, while the optimal temperature range of the cooling water is between 283.15K and 303.15K.

The performance analysis of organic rankine cycles combined CCHP system

The performance analysis of organic rankine cycles combined CCHP system

Analysis and Performance of ORC Based Solar Thermal Power Plant Using Benzene as a Working Fluid

In the present scenario of huge demand of energy and economy create the necessity to give importance to all types of energy resources either it is conventional or nonconventional. Since the rapid consumption of fossil fuel over billions of people across the world are still unable to assess electricity. Furthermore, if the consumption of fossil fuel will be continued then our future generation will certainly have to face the shortage of it and the Global warming potential and ozone layer depletion will also increase. On account of this the Present paper investigates the application of benzene as a working fluid for ORC system. In this paper, performance analysis of organic Rankine cycle with benzene as working fluid has been done to improve efficiency and achieve better economy. This paper also describes clearly that if we want to produce 9kW of power output with the same variation of mass flow rate as well as Reynolds number, the efficiency of ORC system will have to vary from 32.87% to 54.98% and that is possible only when the temperature at the outlet of turbine will be varied from 259.53oC to 127.22oC respectively. Since the fire point of benzene is very low and any instant sparking may cause hazard and hence in our system there is only a liquid to liquid heat transfer device. Boiler of ORC system consists of helical coil copper dipped into a thermal energy reservoir i.e. heat transfer fluid, therminol vp-1 whose upper temperature limit is 415oC.