Rotary Vane Expander Research Articles

Development of Dual Intake Port Technology in ORC-Based Power Unit Driven by Solar-Assisted Reservoir

The ORC-based micro-cogeneration systems exploiting a solar source to generate electricity and domestic hot water (DHW) simultaneously are a promising solution to reduce CO2 emissions in the residential sector. In recent years, a huge amount of attention was focused on the development of a technological solution allowing improved performance of solar ORC-based systems frequently working under off-design conditions due to the intermittence of the solar source availability and to the variability in domestic hot water demand. The optimization efforts are focused on the improvement of component technology and plant architecture. The expander is retained as the key component of such micro-cogeneration units. Generally, volumetric machines are adopted thanks to their better capability to deal with severe off-design conditions. Among the volumetric expanders, scroll machines are one of the best candidates thanks to their reliability and to their flexibility in managing two-phase working fluid. Their good efficiency adds further interest to place them among the best candidate machines to be considered. Nevertheless, similarly to other volumetric expanders, an additional research effort is needed toward efficiency improvement. The fixed built-in volume ratio, in fact, could produce an unsteady under- or over-expansion during vane filling and emptying, mainly when the operating conditions depart from the designed ones. To overcome this phenomenon, a dual intake port (DIP) technology was also introduced for the scroll expander. Such technology allows widening the angular extension of the intake phase, thus adapting the ratio between the intake and exhaust volume (so called built-in volume ratio) to the operating condition. Moreover, DIP technology allows increasing the permeability of the machine, ensuring a resulting higher mass flow rate for a given pressure difference at the expander side. On the other hand, for a given mass flow rate, the expander intake pressure diminishes with a positive benefit on scroll efficiency. DIP benefits were already proven experimentally and theoretically in previous works by the authors for Sliding Rotary Vane Expanders (SVRE). In the present paper, the impact of the DIP technology was assessed in a solar-assisted ORC-based micro-cogeneration system operating with scroll expanders and being characterized by reduced power (hundreds of W). It was found that the DIP Scroll allows elaboration of a 32% higher mass flow rate for a given pressure difference between intake and expander sides for the application at hand. This leads to an average power increase of 10% and to an improvement of up to 5% of the expander mechanical efficiency. Such results are particularly interesting for micro-cogeneration ORC-based units that are solar-assisted. Indeed, the high variability of hot source and DHW demand makes the operation of the DIP expander at a wide range of operating conditions. The experimental activity conducted confirms the suitability of the DIP expander to exploit as much as possible the thermal power available from a hot source even when at variable temperatures during operation.

Experimental and theoretical analysis of a micro-cogenerative solar ORC-based unit equipped with a variable speed sliding rotary vane expander

A promising solution for the Combined Heat and Power (CHP) micro production is certainly represented by Organic Rankine Cycle (ORC)-based power units. In the domestic appliances with electrical power range of the units below 1 kW, the reduced dimensions of the components represent a critical aspect as well as the need to guarantee a high reliability. When the hot source is represented by solar energy, the optimization of the electricity production keeping insured the thermal energy availability represents an aspect which invites to a proper management of the unit. Solar-based ORC-recovery units frequently work in off-design conditions due to the variability of the hot source and to the Domestic Hot Water (DHW) requirements. For this reason, the design and the selection of the components should be carefully performed. The expander is commonly retained the key component of the unit being the one that mainly affects the behaviour. For the mentioned power ranges, the volumetric expander is the best technological option and, among those available, Sliding Rotary Vane Expander (SVRE) are gaining a sensible interest. At off design conditions, according to permeability theory, the expander intake pressure linearly varies with mass flow rate of the Working Fluid (WF) which is the most suitable and easiest parameter to be changed. This modifies the performances of the unit, both from a thermodynamic and technological point of view. In this paper, the speed variation of the expander is considered as control parameter to restore design expander intake pressure. In order to assess a strategy for the speed variation of the expander, in this paper a comprehensive model of the SVRE is presented when it operates in a solar-driven ORC-based unit. The model is physically based and recovers and widens the permeability theory developed by the authors in previous works. An experimental ORC-based unit was fully instrumented and operated, coupled with a reservoir, usually present when flat plate solar collectors are used, which store the thermal energy which fulfils thermal energy requests and feeds the generating unit. The model was widely validated with the experimental data properly conceived for the purpose. In the unit the expander speed was varied and, thanks to the permeability theory, the relationships between WF flowrate variations, inlet expander pressure and expander speed variation were investigated. The potentiality of a control strategy of the expander revolution speed of the expander was fixed as well as a deeper understanding of the SVRE behaviour and relationships between operating variables. In particular, it was observed that varying the speed from 1000 RPM up to 2000 RPM, the expander behaviour was optimized ensuring proper working condition matching with a (30–100 g/s) flowrate range.

Scaling up a woodchip-fired containerized CHP ORC unit toward commercialization

Microcogeneration utilizing organic Rankine cycle technology has seen challenges in commercialization, despite its vast application potential. The market is large, but so is the competition from standard boilers. This was also the case for a previously developed biomass-fired 50 kWth 2 kWe unit intended for large buildings and small industries. Therefore, a scaled-up 120 kWth and 6.2 kWe unit has been proposed with better commercialization prospects.This paper discusses the process of scaling up, designing, assembling and operation of this system. It includes innovative modifications of previously applied technologies regarding the boiler, expander and the overall system configuration. Both units utilize a rotary vane expander as a specific feature of the design. A comparison with the previous smaller unit is performed on several thousand hours of experimental data. The larger unit reaches higher net combined heat and power production efficiency, reaching 89.3%, even though the expander nominal isentropic efficiency slightly drops to 56%. Economic considerations and market feasibility are discussed with respect to the scaling-up from the laboratory scale unit towards commercialization. Thanks to the simplification of the unit, regardless of the scale-up, the absolute cost remains nearly the same for both units.

Feasibility Assessment of a Dual Intake-Port Scroll Expander Operating in an ORC-Based Power Unit

The main driver of research in the road transportation sector is almost certainly the development of technologies which allow for the reduction of CO2 emissions from internal combustion engines (ICEs). Wasted heat recovery (WHR) from the exhaust gases of ICEs based on organic rankine cycle (ORC) power units is one of the most promising technological solutions. However, several issues are raised when the recovery unit is scaled down to small applications, not to mention the fact that thermal sources are characterized by their intrinsically transient nature, as is the case with ICEs. In fact, this leads the ORC unit having to work frequently in off-design conditions. To successfully overcome this issue, the proper design and selection of the expanders are crucial. They are generally chosen from volumetric-type machines, thanks to their capacity to deal with time-varying thermo-fluid dynamic inlet properties. Among them, scroll machines represent one of the best solutions, despite them not yet being optimized as expanders, with them having been studied more as compressors. Dual-intake-port (DIP) technology is a novel solution used to enhance the performance of scroll machines. The effectiveness of this technology was assessed thanks to a comprehensive, experimentally-validated theoretical model of the scroll. It demonstrated that DIP technology can produce a 25% increase in mechanical power with respect to the baseline machine, without modifying the in–out pressure ratio. Maintaining a constant pressure difference across the expander at 5.6 bar, the power grew from 1131 W to 1410 W with the adoption of DIP technology. This power boost is lower than that achieved with a comparable DIP sliding rotary vane expander (SVRE) already studied by the authors, but the DIP Scroll achieved a higher efficiency (50–60%) when compared to the DIP SVRE case (40%).

Development of a 10 kW class axial impulse single stage turboexpander for a micro-CHP ORC unit

Development of micro ORC systems with 1-15 kW power output for micro-cogeneration and waste heat recovery at the Czech Technical University in Prague, University Centre for Energy Efficient Buildings (CTU UCEEB) has over ten years of history with many successes. These include 6 different ORC units, all with in-house designed rotary vane expanders (RVE) of many versions throughout this development. Among main advantages of the RVE belong relatively simple and robust design at low cost even at very small series of single-unit production and all that with acceptable efficiency. The ORC units operate with hexamethyldisiloxane (MM) working fluid at high pressure ratios and expansion ratios and the isentropic efficiency of RVE has a limit at these conditions around 60%, often however only at values around 50%. While this might be enough on a cost side for commercialization of this technology, in pursuit of higher efficiency solutions, different expander technology needs to be selected. A turbo-expander is a logical choice with prospect of higher efficiency. At the same time, a literature review has found a lack of reported detailed experimental data for micro (5-50 kW) turbo-expanders, possibly hindering global development towards economically feasible solutions. A project named Dexpand, “Optimised expanders for small-scale distributed energy systems” aims at these issues by objectives in designing, optimizing, manufacturing and testing several ORC expanders with MM and isobutane and their subsequent performance mapping and comparison. One major task is a design of a turboexpander for a 120 kWth biomass fired microcogeneration ORC unit currently operated at the CTU UCEEB. An axial impulse single stage turboexpander was selected as a suitable choice, providing a prospect of a decent efficiency at technically manageable rotational speed and size. This paper provides a detail of currently performed design activities, starting from boundary conditions specification, over development and optimization of a 1D model, preliminary 2D CFD calculations and finishing in a state of a robust and detailed 3D CFD model with a real gas model. Note that the working fluid, high molar mass organic vapour, is highly non-ideal in its behaviour and the flow conditions with pressure design ratio around 13 is highly supersonic (nozzle outlet isentropic Mach number exceeds 2). The current results based on 3D CFD indicate a prospect of an isentropic efficiency 71% at mechanical power output of 11 kW. Lastly, ongoing and future work is outlined, which includes aerodynamic optimization based on the developed 3D CFD model and construction design of the entire turbine assembly.

А. А. Мерти, С. Норрис, А. Субианторо. Влияние масла на мощность ротационного детандера с четырьмя пересекающимися пластинами = Murthy A. A., Norris S., Subiantoro A. Effects of Lubricating oil on the performance of a Four-Intersecting-Vane Rotary Expander / пер. с англ. М. А. Федоровой

Lubrication plays an important aspect in machinery. It seals internal leakage gaps, reduces friction and cools components. The present investigation is intended to test the effects of lubrication to an expander’s performance. Polyester lubricating oil grades (Grade 48 and Grade 68) were tested at various operating conditions. The expander prototype is of the rotary mechanism with four vanes comprising two intersecting bars. An experimental test rig was designed and built. The pressure diagram as function of rotational angle was recorded by six pressure transducers arranged in the working chamber, based on which the features of the expansion process of the four-intersecting-vane rotary expander were analysed. To start with, the working fluid was compressed air, but the eventual intended application is in a vapour compression refrigeration system. The experimental study revealed that the rotary vane expander worked steadily at different operating conditions. The experimental results showed that the expander flow rate was generally lower with a thinner oil (POE grade 46), whereas the volumetric efficiency increased from 23,2 % to 27,2 %. The adiabatic efficiency decreased from 22,5 % to 18,1 % with a higher viscosity lubricating oil (POE grade 68).

Effects of Lubricating oil on the performance of a Four-Intersecting-Vane Rotary Expander

Lubrication plays an important aspect in machinery. It seals internal leakage gaps, reduces friction and cools components. The present investigation is intended to test the effects of lubrication to an expander’s performance. Polyester lubricating oil grades (Grade 48 and Grade 68) were tested at various operating conditions. The expander prototype is of the rotary mechanism with four vanes comprising two intersecting bars. An experimental test rig was designed and built. The pressure diagram as function of rotational angle was recorded by six pressure transducers arranged in the working chamber, based on which the features of the expansion process of the four-intersecting-vane rotary expander were analysed. To start with, the working fluid was compressed air, but the eventual intended application is in a vapour compression refrigeration system. The experimental study revealed that the rotary vane expander worked steadily at different operating conditions. The experimental results showed that the expander flow rate was generally lower with a thinner oil (POE grade 46), whereas the volumetric efficiency increased from 23.2% to 27.2%. The adiabatic efficiency decreased from 22.5% to 18.1% with a higher viscosity lubricating oil (POE grade 68).

Analytical grid generation and numerical assessment of tip leakage flows in sliding vane rotary machines

The research presents a new analytical grid generation methodology for computational fluid dynamics studies in positive displacement sliding vane rotary machines based on the user defined nodal displacement approach. This method is more inclusive than state of the art ones since it enables the investigation of a broader range of design configurations, such as single, double and multiple-acting vane machines with non-circular housing, slanted blade and asymmetric blade tip profiles. Node number and radial divisions of blade tip are the parameters that affect most the mesh quality. The method was validated against indicated pressure measurements on a rotary vane expander resulting in a confidence interval within 4.31%. The benchmark analysis showed that the proposed method is as accurate as the manual ANSYS ICEM one but more than 1500 times faster (111s instead of 48h to generate 360 grids). The paper further proposes a novel method to track the leakage flows at the blade tip gaps of vane machines through a post-processing routine in ANSYS CFD-Post based on rotating monitoring planes. The leakage assessment on the vane expander case study showed that a 10 μm gap between blade tip and the 76 mm stator led to a 0.06 unit increase of the expander filling factor.

Development and numerical assessment of a regulation strategy for Sliding Rotary Vane Expander based on revolution speed variation

Sliding Rotary Vane Expanders (SVRE) are widely used in ORC-based power units for waste heat recovery in internal combustion engine (ICE) thanks to the capability to handle off-design conditions and their lower speed. In particular, SVRE revolution speed is usually varied together with the pump one to regulate the recovery unit. Nevertheless, this parameter affects SVRE performance and such effects should be taken into account. Thus, in order to reach this goal, in this paper a control strategy based on revolution speed variation was developed for SVRE. Its suitability and effects on expander performance were analyzed through a SVRE model developed in GT-Suite™ environment. The model was experimentally validated thanks to an extensive experimental campaign carried out on a 1.5 kW SVRE installed on an ORC-based power unit fed by the exhaust gases of a 3 liters supercharged Diesel engine. The results confirm the regulation strategy effectiveness as the maximum deviation between the intake-end pressure (object of regulation) and the set-point is 4% of its value for a wide range of operating conditions. Moreover, the numerical results show that the increase of revolution speed until a certain value leads to the expander global efficiency increase and mechanical power too.

Experimental Validation of a New Modeling for the Design Optimization of a Sliding Vane Rotary Expander Operating in an ORC-Based Power Unit

Sliding Rotary Vane Expanders (SVRE) are often employed in Organic Rankine Cycle (ORC)-based power units for Waste Heat Recovery (WHR) in Internal Combustion Engine (ICE) due to their operating flexibility, robustness, and low manufacturing cost. In spite of the interest toward these promising machines, in literature, there is a lack of knowledge referable to the design and the optimization of SVRE: these machines are often rearranged reversing the operational behavior when they operate as compressors, resulting in low efficiencies and difficulty to manage off-design conditions, which are typical in ORC-based power units for WHR in ICE. In this paper, the authors presented a new model of the machine, which, thanks to some specific simplifications, can be used recursively to optimize the design. The model was characterized by a good level of physical representation and also by an acceptable computational time. Despite its simplicity, the model integrated a good capability to reproduce volumetric and mechanical efficiencies. The validation of the model was done using a wide experimental campaign conducted on a 1.5 kW SVRE operated on an ORC-based power unit fed by the exhaust gases of a 3 L supercharged diesel engine. Once validated, a design optimization was run, allowing to find the best solution between two “extreme” designs: a “disk-shaped”—increasing the external diameter of the machine and reducing axial length—and by a “finger-shaped” machine. The predictions of this new model were finally compared with a more complex numerical model, showing good agreement and opening the way to its use as a model-based control tool.

A dual-intake-port technology as a design option for a Sliding Vane Rotary Expander of small-scale ORC-based power units

Volumetric machines are the most suitable candidates to be used as expander in power units based on the Organic Rankine Cycle (ORC) thermodynamic concept, for waste heat recovery of Internal Combustion Engine in the on-the-road transportation sector. In particular, the technology of the Sliding Rotary Vane Expander (SRVE) shows intrinsic advantages thanks to their lower cost, shaping features, easier manufacturing and reliability and, generally speaking, very suitable operative conditions. Nevertheless, they show some disadvantages which are typical of volumetric machines, such as low capacity, limited expansion ratio and power lost by friction.Among the different technologies available to reduce the effects of these aspects (revolution speed increase, elliptical stators or with more complex geometries, tip blade optimization, rolling stators, etc.), the Dual-Intake Port (DIP) was assessed as a promising solution to enhance SVREs performance and operability. However, dual-intake port was still not conceived as design option.In this paper, a novel Sliding Vane Rotary Expander design concept involving a Dual Intake Port expander (DIP) option was developed and compared to the conventional Single Intake Port (SIP) one, under the same operating conditions. Thus, after an experimental comparison between SIP and DIP expanders, under the same conditions of mass flowrate, a theoretical expander model of the latter was validated on a set of experimental results. The model allows to outline the advantages of considering the dual port as a design option: for a specific flow rate and revolution speed, this option allows to reduce the friction losses, which represent a weak point of this volumetric machine. For a given mass flow rate of the working fluid, an additional feature is that it allows a sensible downsizing with respect to the SIP, with an axial dimension reduction up to 50%, ensuring additional weight and space saving. Despite the reduction of the dimensions, DIP produces a comparable mechanical power with respect to SIP, limiting the reduction to 8–10% of the SIP one with a 50% lower mechanical power loss due to friction. For the same flow rate, the added intake port determines a decrease of the intake pressure which is completely beneficial in terms of operating conditions of the overall recovery unit.

On the effects of leakages in Sliding Rotary Vane Expanders

Rotary Vane Expanders (RVE) are very suitable prime movers for ORC-based power units in on-the-road transportation sector. RVEs suffer volumetric efficiency deficits due to leakages which limit the overall expander efficiency and can vanish their intrinsic benefits with respect to the other prime movers. Making reference to a 2 kW Sliding RVE type (SRVE), the paper presents a theoretical and experimental contribution which goes deep into the effect of leakages inside the machine and aims to quantify their amount and effects on the expander performances. The results showed that the volumetric losses increase the mass flow rate aspirated by the machine if the intake pressure is kept constant. This increase favors a greater recovery from the hot source (up to 50%) but part of it bypasses the vanes, producing a volumetric loss. An interesting feature is that part of this additional mass is exchanged among vanes and this produces a beneficial effect on the indicated power (16.6% increase with respect the ideal case). The resulting knowledge further supported the effectiveness of dual intake expander technology which allows to theoretically reduce the leakages between adjacent vane up to 60–70% ensuring an improvement of expander efficiency.

Theoretical and experimental investigations on the radial and axial leakages within a rotary vane expander

Rotary vane expander (RVE) is a perspective type of a volumetric expander for small series manufacturing due to its simple geometry and low manufacturing costs. Performance of this type of expander is usually worse in comparison with other volumetric expanders but it can be improved if we understand well the phenomena that occur during expansion within the vane expander.This work provides a theoretical and experimental analysis of the influence of various leakage pathways on the behaviour of a RVE. The RVE used in this work has been specifically modified for the possibility of adjusting the axial and radial clearances. Experimental data for the both clearances ranging from +0 to +0.5 mm were used to set up a 1D mathematical model, which, provides accuracy of parameter prediction within ±5%. Such model can be further used for optimization and design of RVE. In this paper, the model was used to analyse the effect of reducing manufacturing tolerances on the expander parameters.Analyses are performed for constant pressure difference (common in literature), as well as for the regime of constant heat input of the thermodynamic cycle (better reflects the conditions of the real expander operation and its effect to the entire cycle).

Experimental and Numerical Characterization of the Sliding Rotary Vane Expander Intake Pressure in Order to Develop a Novel Control-Diagnostic Procedure

Waste heat recovery via Organic Rankine Cycle (ORC)-based power units represents one of the most promising solutions to counteract the effects of CO2 emissions on climate change. Nevertheless, several aspects are still limiting its development on the on-the-road transportation sector. Among these aspects, the significant variations of the conditions of the hot source (exhaust gases) are a crucial point. Therefore, the components of the ORC-based unit operate far from the design point if the main operating parameters of the plant are not suitably controlled. The maximum pressure of the cycle is one of the most important variables to be controlled for the importance it has on the effectiveness of the recovery and on safety of operation. In this paper, a wide experimental and theoretical activity was performed in order to define the operating parameters that mostly affect the maximum pressure of the recovery unit. The results showed that the mass flow rate provided by the pump and the expander volumetric efficiency were the main drivers that affect the plant maximum pressure. Subsequently, through a validated model of the expander, a diagnostic map was outlined to evaluate if the expander and, consequently, the whole plant were properly working.

Dual intake rotary vane expander technology: Experimental and theoretical assessment

Rotary Vane Expander is an interesting solution for small-scale ORC power unit due to its reliability, flexibility and competitive cost. As demonstrated by the authors in previous works, the introduction of a secondary intake port leads to an increase of the aspirated mass flow rate and consequently of the mechanical power produced by the machine. In this paper, theoretical and experimental studies were conducted in order to assess the potential benefits in terms of efficiency introduced by the dual intake expander and the trade-off with the produced power for a given pressure-drop. The theoretical results showed that if the relative gain of mechanical power produced by the dual intake technology is higher than that of working fluid mass flow rate, the efficiency grows when the same machines operate at the same upstream and downstream pressures. Two expanders have been designated, built and tested giving the possibility to experimentally verify the performances of a single and a double intake machine. From measured data a mathematical model of the expander was validated, allowing to use it as a virtual platform for further machine optimization and improvement. It was observed that the efficiency gain introduced by the dual intake device depends on the OEM volumetric efficiency and on the pressure ratio. The global efficiency of the dual intake expander grows up to 30% if the volumetric efficiency is 50% and the pressure ratio is 2.3 while the efficiency benefit decreases to 5% if the volumetric efficiency is 70% and the pressure ratio is 3. Nevertheless, even if the global efficiency would be equal for the two machines, the dual intake technology always allows to increase the delivered mechanical power.

Performance investigation of a novel expander coupling organic Rankine cycle: Variable expansion ratio rotary vane expander for variable working conditions

Organic Rankine cycle (ORC) waste heat recovery (WHR) has been proven to be a promising method for low-grade energy reutilization. However, the working conditions can move far from the nominal conditions when the heat source energy varies. This paper presents an investigation of a novel expander for ORC, the variable expansion ratio rotary vane expander (VERRVE), adjusting its expansion ratio (ER) by regulating the outlet opening angle according to variable working conditions. A VERRVE with an adjustable ER range of 1.55–3.02 was first designed. Second, the VERRVE was modeled by GT-SUITE, and its performance at various ERs was investigated. Compared to inlet temperature, the inlet working fluid pressure is the more sensitive influencing factor. Third, this expander was applied to automotive ESC working conditions. An inlet mass flow rate controller was added to ensure that the inlet heat matched the engine exhaust. For the light load condition a50, the influence of the ER is more remarkable. When the ER decreases from 3.02 to 1.83, the output power and exergy efficiency increase by 61.81% and 56.09%, respectively. VERRVE introduces variable ER into ORCs, which is especially recommended for application to ORC WHR systems with variable heat sources.

WEAR BEHAVIOUR OF VANES FOR A ROTARY VANE EXPANDER WITH VARIOUS GRAPHITE MATERIALS UNDER DRY SLIDING CONDITIONS

This study presents tribological properties of various graphite materials of vanes for rotary vane expanders. A test device was developed in order to measure the wear and power dissipation under conditions similar to a real operation of a vane expander. Subsequently, the friction coefficients of vanes for a rotary vane expander were evaluated. Parameters of the test device are based on the vane expander used for an experimental organic Rankine cycle unit. Four materials in total were tested: graphite, antimony-impregnated graphite, 2D carbon fibre-reinforced graphite, and 2.5D carbon fibre-reinforced graphite. Wear tests were performed under dry sliding conditions at the temperature of 115 °C and at 3030 rpm for the total time of about 400 hours. The method of evaluating the wear involved measuring the vane weight loss in relation to the duration of the load. Furthermore, specific wear coefficients were established in order to evaluate the tribological properties of the tested materials. Measurements have shown that carbon fibre materials are the most advantageous in terms of wear. The best friction properties were obtained for the pure graphite.

Experimental development of a kilowatt-scale biomass fired micro – CHP unit based on ORC with rotary vane expander

Micro-cogeneration technologies currently available on the market are too expensive and requiring noble and expensive fuels. Also increasing renewables' shares should favour biomass as a cheap local and available fuel providing dispatchable power. We present a renewable solution based on woodchip combustion system coupled with ORC for applications replacing biomass boilers and producing electricity for own system consumption and a little bit extra. This work describes the design methodology as a complex issue from not only thermodynamic and technical perspective, but also economical and legal. Finally, the technical specifications and operational characteristics of the constructed micro-cogeneration ORC biomass fired system which is in a pre-pilot application stage are presented.This work follows as an extension and follow-up on a paper presented in IV International Seminar on ORC Power Systems, ORC2017, 13–15 September 2017, Milano, Italy.

Experimental and CFD analysis of rotary multi vane expander for small capacity generation

Every year, Indonesia's population increase so as energy demand. To fulfill Indonesia's energy needs, the capacity of energy production should be increased. Indonesia government has made a solution by propose 35.000 MW program to increase energy production and electrification ratio in Indonesia. An insulated area where electricity did not reach, has many problem to get electricity such as limited infrastructure, low fuel energy content, and expensive turbine. To solve these problem, multi-vane expander (MVE) can be used to extract the low energy and is cheap. MVE have many advantages such as cheap, easy to manufacture, able to operate with 2 phase, and able to low speed operation. But, the disadvantage of this type of expander is leakage. In this paper, experimental and CFD analysis of MVE are conducted. The experiment generated power of 25.7 watt with isentropic and volumetric efficiency of 11.6% and 11.7% by using operating condition of 1.5 bar, 115.6 °C, 626 rpm, and mass flow rate of 80 kg/h. The CFD model of the expander is created with the same dimension and operating conditions as experimental. The result for isentropic efficiency is inversely proportional with mass flow rate and for volumetric efficiency, power, and expander rotation are directly proportional with mass flow rate.

Towards development of 1-10 kW pilot ORC units operating with hexamethyldisiloxane and using rotary vane expander

Micro-cogeneration and small scale waste heat recovery has its place in the concept of sustainable future and distributed electricity generation as it should provide environmental, economical and social advantages. ORC belongs among perspective technologies to achieve a successful commercialization. Domain of power output below 10 kW is particularly interesting because it brings a possibility of energy production to a wide range of potential customers. Widespread of solid fuels fired heating systems and a desire for renewable energy suggest a combination of biomass and cogeneration systems.There is an eight-year history of an ORC development at the Czech Technical University aiming at applications for cogeneration and waste heat recovery with power output between 1 and 10 kW. This work shows the overall development over four different ORC units. Development of different concepts, configurations or choice of technologies is presented in this work together with the obtained performance parameters. Common feature of all presented units are use of rotary vane expander (of which three different generations have been designed and tested).