Development of a waste heat recovery orc prototype using an oil-free scroll expander

The world is facing a historical increase in energy demand and energy consumption. As consequence the conventional fossil fuels are depleting faster with an inherent pollution causing severe damages to our environment. Renewable energy sources are considered as a solution to both environmental issue and energy demand. At the same time a lot of waste heat is witnessed in processes in industries. Our objective is to contribute to the development of ORC systems, that appear to us as a good solution to recover this wasted heat. In such waste heat applications, depending on the heat source flow rate and temperature, electrical power output can be as low as a few kilowatts. In this power range, there is no cost effective expansion machine available on the market. On existing prototypes, expansion devices are usually retrofitted volumetric compressors originally designed for refrigeration or air compression applications. Air compressors have the advantage to handle higher inlet temperature but tightness is often an issue in ORC application since the fluids used have a non negligible environmental impact. This paper presents the development of a small-scale WHR ORC unit at the Thermodynamic Laboratory of the University of Liège: the prototype uses a scroll expander, plate heat exchangers, a diaphragm piston pump and a liquid receiver. This system was tested with different working fluids (R123, R245fa and HFE7000) and a thermal efficiency close to 8% was obtained for a net output power of about 2 kWe. The specificity of the proposed prototype is the absence of lubrication: in order to avoid oil circulation in the ORC loop, an oil-free scroll expander is developed. This expander is originally an air scroll compressor that was modified using a magnetic coupling to ensure tightness. The experimental results highlight the good efficiency of the device, despite a relatively high internal leakage due to absence of lubrication. The necessity of using magnetic coupling is also justified by comparing the experimental results with previous ones obtained using mechanical sealing

Experimental Investigation Of An ORC System For A Micro-Solar Power Plant

Because of the depletion of fossil fuels and global warming issues, the world energy sector is undergoing various changes toward increased sustainability. Among the different technologies being developed, solar energy, and more specifically CSP (Concentrated Solar Power) systems are expected to play a key role to supply centralized loads and off-grid areas in the medium-term. Major performance improvements can be achieved by implementing advanced control strategies accounting for the transient and random nature of the solar heat source. In this context, a lab-scale solar power plant has been designed and is under construction for experimental purposes and dynamic analyzes. The test rig includes an ORC unit, a field of parabolic trough collectors and a thermal energy storage. This paper presents the results of an experimental campaign conducted on the ORC module alone. This power unit, designed for a 2.8 kW net electrical output, consists of two scroll expanders in series, an air-cooled condenser, a recuperator, a volumetric pump and an oil-heated evaporator. The ORC engine is constructed using standard mass manufactured components from the HVAC industry, this practice reducing considerably the system cost. The overall unit performance and components effectiveness are presented in different operating conditions and relevant empirical correlations are derived to be implemented in a steady state model of the ORC unit

Working fluid selection and operating maps for Organic Rankine Cycle expansion machines

peer reviewedFluid selection for the Organic Rankine Cycle has been the object of an abundant literature. Most of the scientific publications focus on the cycle thermodynamic efficiency in order to select the best candidate. However, other thermodynamics properties, such as molar mass, or vapor density condition the whole design of the cycle, and its cost. For example, the molar mass influences the number of stages required in the case of an axial turbine; the volume ratio between expander supply and exhaust conditions the possibility to use a volumetric expander (whose internal volume ratio is limited); the vapor density at the expander exhaust determine the size of the expander, and of the condenser; etc. This paper considers a whole range of ORC applications, in terms of power (from the kW-scale to the multi-MW plants), heat source temperature (from 90°C to more than 300°C) or heat source nature (solar, biomass, waste heat recovery, geothermy, etc.). For each of these applications, a screening of the available fluids is performed, and their thermodynamics performance are compared with respect to the foreseen application. A detailed analysis of the most common expansion machines is then conducted, by comparing their respective operating maps for each fluid and for each application type. The considered expansion machines are the radial-inflow turbine, the screw expander, and the scroll expander, since they are the most widely used in commercial applications and/or in scientific literature

Design of a small-scale organic Rankine cycle engine used in a solar power plant

peer reviewedUnder the economic and political pressure due to the depletion of fossil fuels and global warming concerns, it is necessary to develop more sustainable techniques to provide electrical power. In this context, the present study aims at designing, building and testing a small-scale organic Rankine cycle (ORC) solar power plant ( 3 kWe) in order to define and optimize control strategies that could be applied to larger systems. This paper presents a first step of the design of the solar power plant and focuses more specifically on the ORC engine. This design is defined on the basis of simulation models of the ORC engine and takes into account some technical limitations such as the allowed operating ranges and the technical maturity of the components. The final configuration includes a diaphragm pump, two plate heat exchangers for the regenerator and the evaporator, an air-cooled condenser, two hermetic scroll expanders in series and R245fa as the working fluid. Simulations indicate that an efficiency close to 12% for the ORC engine can be reached for evaporating and condensing temperatures of 140 and 358C, respectively

Techno-economic survey of Organic Rankine Cycle (ORC) systems

New heat conversion technologies need to be developed and improved to take advantage of the necessary increase in the supply of renewable energy. The Organic Rankine Cycle is well suited for these applications, mainly because of its ability to recover low-grade heat and the possibility to be implemented in decentralized lower-capacity power plants. In This paper, an overview of the different ORC applications is presented. A market review is proposed including cost figures for several commercial ORC modules and manufacturers. An in-depth analysis of the technical challenges related to the technology, such as working fluid selection and expansion machine issues is then reported. Technological constraints and optimization methods are extensively described and discussed. Finally, the current trends in research and development for the next generation of Organic Rankine Cycles are presented

Experimental evaluation of HCFO-1233zd-e as HFC-245fa replacement in an organic rankine cycle system for low temperature heat sources

[EN] In this work an experimental evaluation of the working fluid HCFO-1233zd-E as HFC-245fa replacement in ORC systems for low temperature heat sources has been conducted. A fully monitored ORC module has been used to test both working fluids at different operating conditions. Due to the different densities of the working fluids, the mass flow rate for HCFO-1233zd-E is approximately 20% lower than for HFC-245fa. This causes thermal and electrical powers to be lower for HCF0-1233zd-E than for HFC245fa. However, net electrical efficiency is similar for both working fluids, ranging from 5% to 9.7% in the tested operating conditions. Regarding the expander performance, various performance indicators are addressed. The expander isentropic performance has a maximum value of 75%, with higher values for HCFO-1233zd-E than for HFC-245fa. The overall efficiency of the expander, similar for both working fluids, ranges from 44% to 57% in the experimental test range. (C) 2016 Elsevier Ltd. All rights reserved.The authors thankfully acknowledge the cooperation of Rank (R) for its support in this project.Molés-Ribera, F.; Navarro Esbri, J.; Peris-Pérez, B.; Mota-Babiloni, A. (2016). Experimental evaluation of HCFO-1233zd-e as HFC-245fa replacement in an organic rankine cycle system for low temperature heat sources. Applied Thermal Engineering. 98:954-961. doi:10.1016/j.applthermaleng.2016.01.011S9549619

Experimental characterization of an ORC (organic Rankine cycle) for power and CHP (combined heat and power) applications from low grade heat sources

An ORC (organic Rankine cycle) module, designed and built for a specific CHP (combined heat and power)) application, is tested in this paper. The aim of the work is to characterize the system performance in the operating range allowed by the ORC. For this purpose, a test procedure has been conducted in a test bench. The heat source has been simulated through a natural gas boiler and a thermal oil heat transfer loop to control the temperature in the low grade range of 90 °C 150 °C. The heat sink has been developed using a dry cooler to control the hot water temperature in the range of 30 °C, corresponding to a power application, to 80 °C, of a small-scale CHP application that provides hot water at 90 °C. Thereby, the results show that the thermal power captured by the ORC, electricity and useful heat produced, increase with the rise of the thermal oil temperature and larger pressure ratios. Moreover, the expander electrical isentropic effectiveness is maximized about 70% for a pressure ratio suitable for a CHP system. The cycle efficiency slightly continues increasing for higher pressure ratios, up to a net electrical efficiency of about 8%.The authors want to acknowledge all the invaluable cooperation of Rank (R), the ORC manufacturer, for its support in this project. Also to thank greatly the Jaume I University for its financial support under the PhD grant PREDOC/2013/28 of 'Convocatoria d'ajudes predoctorals per a la formacio de personal investigador del Pla de promocio de la investigacio de la Universitat Jaume I de Castello (Spain)'.Peris Pérez, B.; Navarro Esbri, J.; Molés Ribera, F.; González, M.; Mota Babiloni, A. (2015). Experimental characterization of an ORC (organic Rankine cycle) for power and CHP (combined heat and power) applications from low grade heat sources. Energy. 82:269-276. https://doi.org/10.1016/j.energy.2015.01.037S2692768

Training of radiotherapy professionals: status, content, satisfaction and improvement suggestions in the Greater Region.

peer reviewed[en] BACKGROUND: The initial training of Radiation Oncology professionals can vary widely across Europe. The aim of this study was to assess the status and content of the initial training programs currently implemented in the Greater Region: Lorraine (Nancy, France), Saarland (Homburg, Germany), Luxembourg, and Liège (Wallonia, Belgium). METHODS: A survey was developed to investigate (1) the overall satisfaction, learning objectives, and teaching methods used during initial training programs and (2) the perceptions of the importance of key professional competencies as described by the CanMEDS (a framework that identifies and describes the abilities physicians require to effectively meet the health care needs of the people they serve). In addition, open-ended questions were used to elicit opinions on room for improvement. Participants (N = 38) were physicians (radiation oncologists (RO) seniors and residents) and radiation therapists (RTTs). RESULTS: Only 21.1% of the respondents declared having acquired all the competencies required for their professional practice during their initial training. Heterogeneity in teaching methods was noted within professional programs but there is no difference between those from RO and RTT in the teaching of technical and relational skills. Relational skills were not addressed in a range of 39.5-57.9% of respondent's curricula. More practical lessons were deemed necessary to improve radiotherapy (RT) training programs. CONCLUSIONS: Radiation oncology professionals expressed the need for more practical teaching, especially in the training of non-technical skills. Regarding the perceived importance of professional aptitudes, radiation oncology professionals highlighted medical and relational skills as the most important competencies

Experimental and thermodynamic analysis of a bottoming Organic Rankine Cycle (ORC) of gasoline engine using swash-plate expander

This paper deals with the experimental testing of an Organic Rankine Cycle (ORC) integrate in a 2 liter turbocharged gasoline engine using ethanol as working fluid. The main components of the cycle are a boiler, a condenser, a pump and a swash-plate expander. Five engine operating points have been tested, they correspond to a nominal heat input into the boiler of 5, 12, 20, 25 and 30 kW. With the available bill of material based on prototypes, power balances and cycles efficiencies were estimated, obtaining a maximum improvement in the ICE mechanical power and an expander shaft power of 3.7% and 1.83 kW respectively. A total of 28 steady-state operating points were measured to evaluate performance of the swash-plate expander prototype. Operating parameters of the expander, such as expander speed and expansion ratio, were shifted. The objective of the tests is to master the system and understand physical parameters influence. The importance of each parameter was analyzed by fixing all the parameters, changing each time one specific value. In these sensitivity studies, maximum ideal and real Rankine efficiency value of 19% and 6% were obtained respectively.This work is part of a research project called "Evaluation of bottoming cycles in IC engines to recover waste heat energies" funded by a National Project of the Spanish Government with reference TRA2013-46408-R.Galindo, J.; Ruiz Rosales, S.; Dolz Ruiz, V.; Royo Pascual, L.; Haller, R.; Nicolas, B.; Glavatskaya, Y. (2015). Experimental and thermodynamic analysis of a bottoming Organic Rankine Cycle (ORC) of gasoline engine using swash-plate expander. Energy Conversion and Management. 103:519-532. https://doi.org/10.1016/j.enconman.2015.06.085S51953210

Investigation of waste heat recovery system at supercritical conditions with vehicle drive cycles

Waste heat recovery (WHR) for internal combustion engines in vehicles using Organic Rankine cycle (ORC) has been a promising technology. The operation of the ORC WHR system in supercritical conditions has a potential to generate more power output and thermal efficiency compared with the conventional subcritical conditions. However, in supercritical conditions, the heat transfer process in the evaporator, the key component of the ORC WHR system, becomes unpredictable as the thermo-physical properties of the working fluid change with the temperature. Furthermore, the transient heat source from the vehicle’s exhaust makes the operation of the WHR system difficult. We investigated the performance of the ORC WHR system at supercritical conditions with engine’s exhaust data from real city and highway drive cycles. The effects of operating variables, such as refrigerant flow rates, evaporator and condenser pressure, and evaporator outlet temperature, on the performance indicators of the WHR system in supercritical conditions were examined. Simulation of operating parameters and the boundary of the WHR system are also included in this paper