scholarly journals The condensing engine: A heat engine for operating temperatures of 100 ℃ and below

2017 ◽  
Vol 232 (4) ◽  
pp. 437-448
Author(s):  
Gerald Müller ◽  
Chun Ho Chan ◽  
Alexander Gibby ◽  
Muhammad Zubair Nazir ◽  
James Paterson ◽  
...  
Keyword(s):  
Heat Engine ◽  
Organic Rankine Cycle ◽  
Cost Effective ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Theoretical Development ◽  
Working Fluid ◽  
Low Grade ◽  
The Difference ◽  
Power Outputs

The cost-effective utilisation of low-grade thermal energy with temperatures below 150 ℃ for electricity generation still constitutes an engineering challenge. Existing technology, e.g. the organic Rankine cycle machines, are complex and only economical for larger power outputs. At Southampton University, the steam condensation cycle for a working temperature of 100 ℃ was analysed theoretically. The cycle uses water as working fluid, which has the advantages of being cheap, readily available, non-toxic, non-inflammable and non-corrosive, and works at and below atmospheric pressure, so that leakage and sealing are not problematic. Steam expansion will increase the theoretical efficiency of the cycle from 6.4% (no expansion) to 17.8% (expansion ratio 1:8). In this article, the theoretical development of the cycle is presented. A 40 Watt experimental engine was built and tested. Efficiencies ranged from 0.02 (no expansion) to 0.055 (expansion ratio 1:4). The difference between theoretical and experimental efficiencies was attributed to significant pressure loss in valves, and to difficulties with heat rejection. It was concluded that the condensing engine has potential for further development.

Experimental Testing of Gerotor and Scroll Expanders Used in, and Energetic and Exergetic Modeling of, an Organic Rankine Cycle

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
James A. Mathias ◽  
Jon R. Johnston ◽  
Jiming Cao ◽  
Douglas K. Priedeman ◽  
Richard N. Christensen
Keyword(s):  
Specific Volume ◽  
Experimental Testing ◽  
Organic Rankine Cycle ◽  
Volume Ratio ◽  
Cost Effective ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Working Fluid ◽  
Low Grade ◽  
Scroll Expanders

This paper presents the experimental testing of relatively cost-effective expanders in an organic Rankine cycle (ORC) to produce power from low-grade energy. Gerotor and scroll expanders were the two types of expanders tested to determine their applicability in producing power from low-grade energy. The results of the experimental testing showed that both types of expanders were good candidates to be used in an ORC. The gerotor and scroll expanders tested produced 2.07 kW and 2.96 kW, and had isentropic efficiencies of 0.85 and 0.83, respectively. Also the paper presents results of an analytical model produced that predicted improved cycle efficiency with certain changes. One change was the flow rate of the working fluid in the cycle was properly matched with the inlet pocket volume and rotational speed of the expander. Also, the volumetric expansion ratio of the expander was matched to the specific volume ratio of the working fluid (R-123) across the expander. The model incorporated the efficiencies of the expanders and pump obtained during experimental testing, and combined two expanders in series to match the specific volume ratio of the working fluid. The model determined the power produced by the expanders, and subtracted the power required by the working fluid pump and the condenser fan. From that, the model calculated the net power produced to be 6271 W and the overall energy efficiency of the cycle to be 7.7%. When the ORC was simulated to be integrated with the exhaust of a stationary engine, the exergetic efficiency, exergy destroyed, and reduction in diesel fuel while still producing the same amount of power during 2500 h of operation were 22.1%, 22,169 W, and 4,012 L (1060 U.S. gal), respectively. Consequently, the model presents a very realistic design based on results from experimental testing to cost-effectively use low-grade energy.

1-D Model Analysis of Tesla Turbine for Small Scale Organic Rankine Cycle (ORC) System

2017 ◽  
Author(s):  
Jian Song ◽  
Chun-wei Gu
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Organic Rankine Cycle ◽  
Axial Flow ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Working Fluid ◽  
Small Scale ◽  
Low Grade ◽  
D Model

Energy shortage and environmental deterioration are two crucial issues that the developing world has to face. In order to solve these problems, conversion of low grade energy is attracting broad attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be one of the most effective methods for the utilization of low grade heat sources. Turbine is a key component in ORC system and it plays an important role in system performance. Traditional turbine expanders, the axial flow turbine and the radial inflow turbine are typically selected in large scale ORC systems. However, in small and micro scale systems, traditional turbine expanders are not suitable due to large flow loss and high rotation speed. In this case, Tesla turbine allows a low-cost and reliable design for the organic expander that could be an attractive option for small scale ORC systems. A 1-D model of Tesla turbine is presented in this paper, which mainly focuses on the flow characteristics and the momentum transfer. This study improves the 1-D model, taking the nozzle limit expansion ratio into consideration, which is related to the installation angle of the nozzle and the specific heat ratio of the working fluid. The improved model is used to analyze Tesla turbine performance and predict turbine efficiency. Thermodynamic analysis is conducted for a small scale ORC system. The simulation results reveal that the ORC system can generate a considerable net power output. Therefore, Tesla turbine can be regarded as a potential choice to be applied in small scale ORC systems.

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.

scholarly journals Prospects of Trilateral Flash Cycle (TFC) for Power Generation from Low Grade Heat Sources

2018 ◽  
Vol 64 ◽  
pp. 06004 ◽  
Author(s):  
Iqbal Md Arbab ◽  
Rana Sohel ◽  
Ahmadi Mahdi ◽  
Close Thomas ◽  
Date Abhijit ◽  
...  
Keyword(s):  
Power Generation ◽  
Organic Rankine Cycle ◽  
Thermodynamic Cycle ◽  
Cost Effective ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade ◽  
Power Stations ◽  
Expansion Stage ◽  
Low Grade Heat

Despite the current energy crisis, a large amount of low grade heat (below 100oC) is being wasted for the lack of cost effective energy conversion technology. In the case of the conventional Organic Rankine Cycle (ORC) based geothermal power stations, only about 20% of available heat can be utilised due to a technological limitation as there is a phase change in the working fluid involved during the addition of heat which decreases utilisation effectiveness of the system. Therefore, in this paper, a trilateral flash cycle (TFC) based system has been studied to find out its prospect for utilizing more power from the same heat resources as the ORC. The TFC is a thermodynamic cycle that heats the working fluid as a saturated liquid from which it starts its expansion stage. The flash expansion is achieved by feeding the saturated high-pressured liquid working fluid through a convergent-divergent nozzle at which point it undergoes a flash expansion in the low-pressure environment of the generator housing. The momentum of the working fluid is extracted via a Pelton wheel and the cycle is completed with working fluid condensation and pressurisation. The analytical comparative study between the ORC and TFC based system shows that the TFC has about 50% more power generation capability and almost zero contribution on global warming.

Numerical Investigation of Velocity Coefficient for Organic Turbine Nozzles Using MM As Working Fluid

2018 ◽  
Author(s):  
Laihe Zhuang ◽  
Guoqiang Xu ◽  
Jie Wen ◽  
Bensi Dong
Keyword(s):  
High Efficiency ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Influential Factors ◽  
Numerical Results ◽  
Working Fluid ◽  
Maximum Deviation ◽  
Low Grade ◽  
Velocity Coefficient

Organic Rankine cycle (ORC) has gained an increasing worldwide attention due to its high efficiency in converting low-grade thermal energy into electricity. The expander is the most critical component in the ORC system. Among the influential factors that define the performance of the expander, the velocity coefficient of the nozzle is crucial. This work numerically investigates the effects of the nozzle height, length, surface roughness, outlet geometric angle, and expansion ratio, on the velocity coefficient of the nozzle in the ORC turbine with hexamethyldisiloxane (MM) as working fluid. In the 3-D viscous numerical analysis, the shear stress transports k-ω turbulence model is employed and the numerical method is verified by the experimental data of the nozzle with pressured air based on hotwire technology. The numerical results show that the velocity coefficient is almost independent of expansion ratio compared to other factors due to the relatively small flow boundary layer and high Reynolds number. Since the existing correlations for the gas nozzle cannot well predict the velocity coefficient of the organic nozzle, an empirical equation is proposed according to the numerical results with the maximum deviation of 3.0%.

Multi-Vane Expanders as Prime Movers in Low-Grade Energy Engines

1986 ◽  
Vol 200 (2) ◽  
pp. 117-125 ◽  
Author(s):  
O Badr ◽  
D Probert ◽  
P W O'Callaghan
Keyword(s):  
Low Temperature ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Low Grade ◽  
Small Power ◽  
Operating Variables ◽  
Positive Displacement ◽  
Temperature Heat ◽  
Prime Movers ◽  
Power Outputs

Multi-vane expanders possess many advantages, over turbines and other positive-displacement machines, as prime movers for low-grade energy engines of small power outputs. It has been found that the performances of such expanders can be improved considerably by optimizing their design and operating variables. For an organic Rankine-cycle engine, utilizing low-temperature heat as the input, a multi-vane expander with isentropic efficiencies exceeding 73 per cent at rotational speeds up to 3000 r/min was designed, built and demonstrated.

Shape Optimization of an Organic Rankine Cycle Radial Turbine Nozzle

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
David Pasquale ◽  
Antonio Ghidoni ◽  
Stefano Rebay
Keyword(s):  
Numerical Solutions ◽  
Organic Rankine Cycle ◽  
Strong Shock ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Computational Grids ◽  
Working Fluid ◽  
Optimization Strategy ◽  
Radial Turbine ◽  
Wide Range

During the last decade, organic Rankine cycle (ORC) turbogenerators have become very attractive for the exploitation of low-temperature heat sources in the small to medium power range. Organic Rankine cycles usually operate in thermodynamic regions characterized by high pressure ratios and strong real-gas effects in the flow expansion, therefore requiring a nonstandard turbomachinery design. In this context, due to the lack of experience, a promising approach for the design can be based on the intensive use of computational fluid dynamics (CFD) and optimization procedures to investigate a wide range of possible configurations. In this work, an advanced global optimization strategy is coupled with a state-of-the-art CFD solver in order to assist in the design of ORC turbines. In particular, a metamodel assisted genetic algorithm, based on the so-called `off-line trained’ metamodel technique, has been employed. The numerical solutions of the two-dimensional (2D) Euler equations are computed with the in-house built code zFlow. The working fluid is toluene, whose thermodynamic properties are evaluated by an accurate equation of state, available in FluidProp. The computational grids created during the optimization process have been generated through a fully automated 2D unstructured mesh algorithm based on the advancing-Delaunnay strategy. The capability of this procedure is demonstrated by improving the design of an existing one-stage impulse radial turbine, where a strong shock appears in the stator channel due to the high expansion ratio. The goal of the optimization is to minimize the total pressure losses and to obtain a uniform axisymmetric stream at the stator discharge section, in terms of both the velocity magnitude and direction of the flow.

scholarly journals Integrated Vapor Compression Chiller with Bottoming Organic Rankine Cycle and Onsite Low-Grade Renewable Energy

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6401
Author(s):  
Muhammad Tauseef Nasir ◽  
Michael Chukwuemeka Ekwonu ◽  
Javad Abolfazali Esfahani ◽  
Kyung Chun Kim
Keyword(s):  
Renewable Energy ◽  
Heat Source ◽  
Energy Input ◽  
Cooling Water ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Sensitivity Analyses ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Low Grade

The present study offers a scheme to improve the performance of existing large-scale chillers. The system involves raising the temperature of the chiller’s cooling water stream using renewable energy sources by incorporating an organic Rankine cycle (ORC). The thermal analysis was conducted by raising the temperature of one-third of the approximately 200 ton chiller’s cooling water. The investigation was considered for ORC evaporator inlet temperature of 90~120 °C by the step of 10 °C. Various working fluids for the different ORC evaporator inlet temperatures were examined. Sensitivity analyses conducted on the degree of superheating, degree of subcooling, condenser saturation temperature, pinch point temperature differences of the ORC evaporator and condenser, and the mass flowrates of the heating and cooling streams were also reported. Genetic algorithm was employed to carry out the optimization. The best options for the ORC working fluid at the heating source ORC evaporator inlet temperatures of 90 °C was found to be DME, presenting an improvement of 48.72% in comparison with the rated coefficient of performance (COP) value of the VCC, with a renewable energy input requirement of 710 kW. At the heat source temperatures of 100 °C and 110 °C, butene, which presented an improvement in the COP equal to 48.76% and 68.85%, respectively, with the corresponding renewable energy requirements of 789.6 kW and 852 kW, was found to be the ideal candidate. Meanwhile, at the heat source inlet temperature of 120 °C, R1233zd (E), representing an improvement of 140.88% with the renewable energy input of around 1061 kW, was determined to be the most favorable ORC working fluid candidate.

scholarly journals Addressing Industrial Waste Heat Supply Variability With Organic Rankine Cycle Systems Incorporating Thermal Energy Storage

2021 ◽  
Author(s):  
Bipul Krishna Saha ◽  
Basab Chakraborty ◽  
Rohan Dutta
Keyword(s):  
Power Generation ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Low Grade

Abstract Industrial low-grade waste heat is lost, wasted and deposited in the atmosphere and is not put to any practical use. Different technologies are available to enable waste heat recovery, which can enhance system energy efficiency and reduce total energy consumption. Power plants are energy-intensive plants with low-grade waste heat. In the case of such plants, recovery of low-grade waste heat is gaining considerable interest. However, in such plants, power generation often varies based on market demand. Such variations may adversely influence any recovery system's performance and the economy, including the Organic Rankine Cycle (ORC). ORC technologies coupled with Cryogenic Energy Storage (CES) may be used for power generation by utilizing the waste heat from such power plants. The heat of compression in a CES may be stored in thermal energy storage systems and utilized in ORC or Regenerative ORC (RORC) for power generation during the system's discharge cycle. This may compensate for the variation of the waste heat from the power plant, and thereby, the ORC system may always work under-designed capacity. This paper presents the thermo-economic analysis of such an ORC system. In the analysis, a steady-state simulation of the ORC system has been developed in a commercial process simulator after validating the results with experimental data for a typical coke-oven plant. Forty-nine different working fluids were evaluated for power generation parameters, first law efficiencies, purchase equipment cost, and fixed investment payback period to identify the best working fluid.

Moment Analysis of a Scroll Expander Used in an Organic Rankine Cycle

2014 ◽  
Author(s):  
Amrita Sengupta ◽  
Prashant Kumar ◽  
Pardeep Garg ◽  
Nirmal Hui ◽  
Matthew S. Orosz ◽  
...  
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Moment Analysis ◽  
Superior Performance ◽  
Working Fluid ◽  
Small Scale ◽  
Inlet Temperature ◽  
Positive Displacement ◽  
Scroll Expander

Recent studies on small-scale power generation with the organic Rankine cycle suggest superior performance of positive displacement type of expanders compared to turbines. Scroll expanders in particular achieve high isentropic efficiencies due to lower leakage and frictional losses. Performance of scroll machines may be enhanced by the use of non-circular involute curves in place of the circular involutes resulting non-uniform wall thickness. In this paper, a detailed moment analysis is performed for such an expander having volumetric expansion ratio of 5 using thermodynamic models proposed earlier by one of the present authors. The working fluid considered in the power cycle is R-245fa with scroll inlet temperature of 125 °C for a gross power output of ∼3.5 kW. The model developed in this paper is verified with an air scroll compressor available in the literature and then applied to an expander. Prediction of small variation of moment with scroll motion recommends use of scroll expander without a flywheel over other positive displacement type of expanders, e.g. reciprocating, where a flywheel is an essential component.

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