A review of expanders for power generation in small-scale organic Rankine cycle systems: Performance and operational aspects

Żywica, Grzegorz; Kaczmarczyk, Tomasz Z.; Ihnatowicz, Eugeniusz

doi:10.1177/0957650916661465

Cited by 48 publications

(12 citation statements)

References 26 publications

(53 reference statements)

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“…The upper limit is imposed by the flammability and low chemical stability of the organic fluids at high temperatures, while the lower one by their vapour pressure which, in turn, limits the efficiency and the output of ORC units at extremely low temperatures. For waste source capacities from 10 kW up to 200 kW, ORC systems equipped with positive displacement machines are preferred to the ones with axial or centrifugal turbines [19] (Fig. 2).…”

Section: High-grade Waste Heat Potentialmentioning

confidence: 99%

Review of supercritical carbon dioxide (sCO2) technologies for high-grade waste heat to power conversion

2020

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In the European Industry, 275 TWh of thermal energy is rejected into the environment at temperatures beyond 300 °C. To recover some of this wasted energy, bottoming thermodynamic cycles using supercritical carbon dioxide (sCO 2) as working fluid are a promising technology for the conversion of the waste heat into power. CO 2 is a non-flammable and thermally stable compound, and due to its favourable thermo-physical properties in the supercritical state, can lead to high cycle efficiencies and a substantial reduction in size compared to alternative heat to power conversion technologies. In this work, a brief overview of the sCO 2 power cycle technology is presented. The main concepts behind this technology are highlighted, including key technological challenges with the major components such as turbomachinery and heat exchangers. The discussion focuses on heat to power conversion applications and benefits of the experience gained from the design and construction of a 50 kWe sCO 2 test facility at Brunel University London. A comparison between sCO 2 power cycles and conventional heat to power conversion systems is also provided. In particular, the operating ranges of sCO 2 and other heat to power systems are reported as a function of the waste heat source temperature and available thermal power. The resulting map provides insights for the preliminary selection of the most suitable heat to power conversion technology for a given industrial waste heat stream.

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Section: High-grade Waste Heat Potentialmentioning

confidence: 99%

Review of supercritical carbon dioxide (sCO2) technologies for high-grade waste heat to power conversion

2020

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“…ORC systems can also be fed with waste heat coming from industrial processes or combustion engines [5]. For electricity generation in such systems, various types of volumetric and dynamic expanders [6] can be used, such as screw expanders, scroll expanders [7], piston expanders [8], vane expanders [9] or turbine expanders [10]. In micro-power ORC systems, microturbines of different types are increasingly used as expanders [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Investigation of dynamic properties of the microturbine with a maximum rotational speed of 120 krpm – predictions and experimental tests

Żywica¹,

Kaczmarczyk²,

Breńkacz³

et al. 2020

J. vibroeng.

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Advances in the development of analysis and design methods for fluid-flow machines have enabled both their multi-criteria optimisation and miniaturisation. To decrease the size of such a machine whilst, at the same time, maintaining its output power level, the rotor's rotational speed needs to be increased. It is the reason for serious difficulties with respect to the rotor dynamics and the selection of a bearing system. This article discusses the simulation analysis and experimental research carried out on a prototypical microturbine, designed for use in a domestic ORC (organic Rankine cycle) cogeneration system. During the design process, the basic assumption was to develop a turbomachine, whose dimensions would have been as small as possible and whose output electric power would have been about 1 kilowatt. A supersonic impulse turbine, with a nominal rotational speed of 100,000 rpm, was used in order to obtain high flow efficiency. The maximum speed of the rotor was determined at a level of 120,000 rpm. The article presents the results of analyses made at the design stage and preliminary results of the experimental research. The numerical simulations covered the bearing system optimisation and the rotor dynamics analysis. Next, based on the outcomes of these analyses, a decision was made to use non-conventional gas bearings which are fed by the low-boiling medium's vapour that comes from the ORC system. Within the framework of the experimental research, the dynamic behaviour of the turbogenerator was examined in terms of the rotational speed and produced energy. The performed measurements are proof of very good dynamic properties of the tested machine and after the research was over it was concluded that there were absolutely no signs of wear of the turbogenerator's subassemblies.

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“…In the past few decades, an enormous amount of researches have been carried out on ORC, focusing on working fluid selection [6][7], expander design [7][8], cycle configuration modification [9][10], optimum design of heat exchanger [11][12], system optimization [13][14], and experimental research on ORC system [15][16], etc. Regarding to optimization researches on ORC, there are single-objective and multi-objective optimizations based on different evaluation criteria.…”

Section: Introductionmentioning

confidence: 99%

Multi-Objective Optimization of Organic Rankine Cycle for Low-Grade Waste Heat Recovery

et al. 2019

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The organic Rankine cycle (ORC) is considered as one of the most viable technology to recover low-grade waste heat. A multi-objective optimization model is established to simultaneously derive the maximum exergy efficiency and the minimum electricity production cost (EPC) of a specific ORC system by employing the genetic algorithm (GA). Evaporation temperature and condensation temperature are selected as decision variables. At first, variations of exergy efficiency and EPC with evaporation temperature and condensation temperature are investigated respectively using R245fa, R245ca, R600, R600a, R601 and R601a as working fluids. Subsequently, a multi-objective optimization is performed and the Pareto frontiers for various working fluids are obtained. Results indicate that performance of the specific ORC system with R245fa as working fluid is better that with other working fluids.

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A review of expanders for power generation in small-scale organic Rankine cycle systems: Performance and operational aspects

Cited by 48 publications

References 26 publications

Review of supercritical carbon dioxide (sCO2) technologies for high-grade waste heat to power conversion

Review of supercritical carbon dioxide (sCO2) technologies for high-grade waste heat to power conversion

Investigation of dynamic properties of the microturbine with a maximum rotational speed of 120 krpm – predictions and experimental tests

Multi-Objective Optimization of Organic Rankine Cycle for Low-Grade Waste Heat Recovery

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