Waste heat recovery through organic flash cycle (OFC) using R245fa–R600 mixture as the working fluid

Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.

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Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration ◽

10.1115/gt2015-43392 ◽

2015 ◽

Cited By ~ 3

Author(s):

Fredrik Ahlgren ◽

Maria E. Mondejar ◽

Magnus Genrup ◽

Marcus Thern

Keyword(s):

Power Output ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Operating Conditions ◽

Maritime Transportation ◽

Working Fluid ◽

Net Power Output

Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

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Exergy analysis of the Szewalski cycle with a waste heat recovery system

Archives of Thermodynamics ◽

10.1515/aoter-2015-0020 ◽

2015 ◽

Vol 36 (3) ◽

pp. 25-48 ◽

Cited By ~ 2

Author(s):

Tomasz Kowalczyk ◽

Paweł Ziółkowski ◽

Janusz Badur

Keyword(s):

Heat Recovery ◽

Waste Heat Recovery ◽

Power Plants ◽

Exergy Analysis ◽

Waste Heat ◽

Reference Conditions ◽

Heat Rate ◽

Working Fluid ◽

Regeneration System ◽

Waste Heat Recovery System

Abstract The conversion of a waste heat energy to electricity is now becoming one of the key points to improve the energy efficiency in a process engineering. However, large losses of a low-temperature thermal energy are also present in power engineering. One of such sources of waste heat in power plants are exhaust gases at the outlet of boilers. Through usage of a waste heat regeneration system it is possible to attain a heat rate of approximately 200 MWth, under about 90 °C, for a supercritical power block of 900 MWel fuelled by a lignite. In the article, we propose to use the waste heat to improve thermal efficiency of the Szewalski binary vapour cycle. The Szewalski binary vapour cycle provides steam as the working fluid in a high temperature part of the cycle, while another fluid – organic working fluid – as the working substance substituting conventional steam over the temperature range represented by the low pressure steam expansion. In order to define in detail the efficiency of energy conversion at various stages of the proposed cycle the exergy analysis was performed. The steam cycle for reference conditions, the Szewalski binary vapour cycle as well as the Szewalski hierarchic vapour cycle cooperating with a system of waste heat recovery have been comprised.

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Optimization of an Organic Rankine Cycle-Based Waste Heat Recovery System Using a Novel Target-Temperature-Line Approach

Journal of Energy Resources Technology ◽

10.1115/1.4050261 ◽

2021 ◽

Vol 143 (9) ◽

Author(s):

Md. Zahurul Haq

Keyword(s):

Heat Exchange ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Optimum Operating ◽

Working Fluid ◽

Operating Parameters ◽

Target Temperature

Abstract Organic Rankine cycle (ORC)-based waste heat recovery (WHR) systems are simple, flexible, economical, and environment-friendly. Many working fluids and cycle configurations are available for WHR systems, and the diversity of working fluid properties complicates the synergistic integration of the efficient heat exchange in the evaporator and net output work. Unique guidelines to select a proper working fluid, cycle configuration and optimum operating parameters are not readily available. In the present study, a simple target-temperature-line approach is introduced to get the optimum operating parameters for the subcritical ORC system. The target-line is the locus of temperatures satisfying the pinch-point temperature difference along the length of the heat exchanger. Employing the approach, study is carried out with 38 pre-selected working fluids to get the optimum operating parameters and suitable fluid for heat source temperatures ranging from 100 °C to 300 °C. Results obtained are analyzed to get cross-correlations between key operating and performance parameters using a heat-map diagram. At the optimum condition, optimal working fluid’s critical temperature and pressure, evaporator saturation temperature, effectivenesses of the heat exchange in the evaporator, cycle, and overall WHR system exhibit strong linear correlations with the heat source temperature.

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Economic and Exergo-Advance Analysis of a Waste Heat Recovery System Based on Regenerative Organic Rankine Cycle under Organic Fluids with Low Global Warming Potential

Energies ◽

10.3390/en13061317 ◽

2020 ◽

Vol 13 (6) ◽

pp. 1317 ◽

Cited By ~ 7

Author(s):

Guillermo Valencia Ochoa ◽

Cesar Isaza-Roldan ◽

Jorge Duarte Forero

Keyword(s):

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Working Fluid ◽

Exhaust Gases ◽

Waste Heat Recovery System ◽

Recovery System ◽

Heat Recovery System

The waste heat recovery system (WHRS) is a good alternative to provide a solution to the waste energy emanated in the exhaust gases of the internal combustion engine (ICE). Therefore, it is useful to carry out research to improve the thermal efficiency of the ICE through a WHRS based on the organic Rankine cycle (ORC), since this type of system takes advantage of the heat of the exhaust gases to generate electrical energy. The organic working fluid selection was developed according to environmental criteria, operational parameters, thermodynamic conditions of the gas engine, and investment costs. An economic analysis is presented for the systems operating with three selected working fluids: toluene, acetone, and heptane, considering the main costs involved in the design and operation of the thermal system. Furthermore, an exergo-advanced study is presented on the WHRS based on ORC integrated to the ICE, which is a Jenbacher JMS 612 GS-N of 2 MW power fueled with natural gas. This advanced exergetic analysis allowed us to know the opportunities for improvement of the equipment and the increase in the thermodynamic performance of the ICE. The results show that when using acetone as the organic working fluid, there is a greater tendency of improvement of endogenous character in Pump 2 of around 80%. When using heptane it was manifested that for the turbine there are near to 77% opportunities for improvement, and the use of toluene in the turbine gave a rate of improvement of 70%. Finally, some case studies are presented to study the effect of condensation temperature, the pinch point temperature in the evaporator, and the pressure ratio on the direct, indirect, and fixed investment costs, where the higher investment costs were presented with the acetone, and lower costs when using the toluene as working fluid.

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Design and Operational Control Strategy for Optimum Off-Design Performance of an ORC Plant for Low-Grade Waste Heat Recovery

Energies ◽

10.3390/en13215846 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5846

Author(s):

Fabio Fatigati ◽

Diego Vittorini ◽

Yaxiong Wang ◽

Jian Song ◽

Christos N. Markides ◽

...

Keyword(s):

Power Unit ◽

Control Strategy ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Combustion Engine ◽

Working Fluid ◽

Thermal Source ◽

Low Grade ◽

Gear Pump

The applicability of organic Rankine cycle (ORC) technology to waste heat recovery (WHR) is currently experiencing growing interest and accelerated technological development. The utilization of low-to-medium grade thermal energy sources, especially in the presence of heat source intermittency in applications where the thermal source is characterized by highly variable thermodynamic conditions, requires a control strategy for off-design operation to achieve optimal ORC power-unit performance. This paper presents a validated comprehensive model for off-design analysis of an ORC power-unit, with R236fa as the working fluid, a gear pump, and a 1.5 kW sliding vane rotary expander (SVRE) for WHR from the exhaust gases of a light-duty internal combustion engine. Model validation is performed using data from an extensive experimental campaign on both the rotary equipment (pump, expander) and the remainder components of the plant, namely the heat recovery vapor generator (HRVH), condenser, reservoirs, and piping. Based on the validated computational platform, the benefits on the ORC plant net power output and efficiency of either a variable permeability expander or of sliding vane rotary pump optimization are assessed. The novelty introduced by this optimization strategy is that the evaluations are conducted by a numerical model, which reproduces the real features of the ORC plant. This approach ensures an analysis of the whole system both from a plant and cycle point of view, catching some real aspects that are otherwise undetectable. These optimization strategies are considered as a baseline ORC plant that suffers low expander efficiency (30%) and a large parasitic pumping power, with a backwork ratio (BWR) of up to 60%. It is found that the benefits on the expander power arising from a lower permeability combined with a lower energy demand by the pump (20% of BWR) for circulation of the working fluid allows a better recovery performance for the ORC plant with respect to the baseline case. Adopting the optimization strategies, the average efficiency and maximum generated power increase from 1.5% to 3.5% and from 400 to 1100 W, respectively. These performances are in accordance with the plant efficiencies found in the experimental works in the literature, which vary between 1.6% and 6.5% for similar applications. Nonetheless, there is still room for improvement regarding a proper design of rotary machines, which can be redesigned considering the indications resulting from the developed optimization analysis.

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Phase Change Material as Pump in an Organic Rankine Cycle

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.575.662 ◽

2014 ◽

Vol 575 ◽

pp. 662-667

Author(s):

Barghav Subramony Hariharan ◽

Kaushik Suresh

Keyword(s):

Phase Change ◽

Phase Change Material ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Electrical Energy ◽

Rankine Cycle ◽

Working Fluid ◽

Change Material

Organic Rankine Cycles (ORC) is predominantly used in waste heat recovery applications because of their low temperature working range. The main efficiency enhancement operation in an Organic Rankine Cycle is reducing the pump work .The pump converts electrical energy to flow energy. This input reduced and output maintained at the same level gives us a more efficient waste heat recovery system. The pump work can also be achieved by using a material that has the ability to expand on heating and revert back to its original state on cooling. The expansion property of the material is used to compress and drive the operating fluid through the cycle. Material that was observed to possess such properties was Phase Change Material. Conventionally PCM were used as thermal storage to preheat the working fluid in an ORC but a novel idea is to make the PCM utilize the heat rejected from the condenser and do the pump work. This paper discusses the various desirable properties of PCM to perform pump work efficiently and also the general layout and working of ORC system using PCM. The working fluid selected is toluene

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Organic Rankine Cycle for Waste Heat Recovery in a Hybrid Vehicle

Volume 4: 12th International Conference on Advanced Vehicle and Tire Technologies; 4th International Conference on Micro- and Nanosystems ◽

10.1115/detc2010-28816 ◽

2010 ◽

Cited By ~ 1

Author(s):

Quazi E. Hussain ◽

David R. Brigham

Keyword(s):

Fuel Economy ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Operating Conditions ◽

Working Fluid ◽

Drive Cycle ◽

Exhaust Heat

The Rankine cycle is used commercially to generate power in stationary power plants using water as the working fluid. For waste heat recovery applications, where the temperature is lower, water is typically replaced by a carefully selected organic fluid. This work is based on using the waste heat in an automobile to generate electricity using the Organic Rankine cycle (ORC) with R245fa (1, 1, 1, 3, 3 penta-fluoropropane) as the working fluid. The electricity thus generated can be used to drive the accessory load or charge the battery which in any case helps improve the fuel economy. A simple transient numerical model has been developed that is capable of capturing the main effects of this cycle. Results show that exhaust heat alone can generate enough electricity that is capable of bringing about an improvement to the fuel economy under transient drive cycle conditions. Power output during EPA Highway drive cycle is much higher than EPA City due to higher exhaust mass flow rate and temperature. Time needed to reach operating conditions or in other words, the warm-up time plays an important role in the overall drive cycle output. Performance is found to improve significantly when coolant waste heat is used in conjunction with the residual exhaust heat to pre-heat the liquid. A sizing study is also performed to keep the cost, weight, and packaging requirement down without sacrificing too much power. With careful selection of heat exchanger design parameters, it has been demonstrated that the backpressure on the engine can be actually lowered by cooling off the exhaust gas. This lower backpressure will further boost the fuel economy gained by the electricity produced by the Rankine bottoming cycle.

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Development of a 125 kW AMB Expander/Generator for Waste Heat Recovery

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4002660 ◽

2011 ◽

Vol 133 (7) ◽

Cited By ~ 9

Author(s):

Lawrence A. Hawkins ◽

Lei Zhu ◽

Eric J. Blumber

Keyword(s):

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Magnetic Bearings ◽

Working Fluid ◽

Worst Case ◽

Waste Heat Recovery System ◽

Heat System ◽

Recovery System ◽

Heat Recovery System

The development and testing of an integrated power module (IPM) for a waste heat recovery system is described. The IPM is part of a waste heat recovery system based on the organic Rankine cycle. The waste heat system can recover energy from a wide variety of heat sources including landfill gas, reciprocating engine exhaust, solar, geothermal, boilers, and other industrial processes. The IPM incorporates a high performance, high speed permanent magnet generator with an integrated expansion turbine and low loss magnetic bearings. The IPM operates between 20,000 rpm and 26,500 rpm depending on the energy available from the heat source. The varying frequency voltage supplied by the generator is connected to the grid using an active/active power electronics package that can deliver power at 400–480 Vac (50 Hz or 60 Hz). Active magnetic bearings (AMBs) were chosen for the application because they can operate directly in the working fluid, have low losses, and provide high reliability and remote monitoring capabilities. This system has a flow-through design and an inboard impeller layout that produces desirable rotordynamics for a simple magnetic bearing control. An extensive shop testing procedure is described, and measurements and predictions are presented, showing good correlation. Shop testing of the IPM in the waste heat system has been completed for 15 systems. The magnetic bearings and backup bearings have performed as designed. The thrust balancing system has limited the thrust load that must be reacted by the axial magnetic bearings to 25% of the design load capacity in the worst case. The first field unit was installed in April 2009 at a biogas site.

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