10:00
Prototypes I
Chair: Prof. Teemu Turunen-Saaresti
10:00
20 mins
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COMPACT TORUS-SHAPED ORGANIC RANKING CYCLE FOR DISTRIBUTED SOLAR THERMAL POWER GENERATION
Bryce Shaffer
Abstract: As organic rankine cycles continue to gain a foothold in the energy landscape, they will face similar challenges as refrigeration cycles have throughout their history. This is specifically true for smaller ORC’s (10kW and below) used for solar to thermal distributed power generation systems, where components such as cost, size, weight, efficiency and management of ozone depleting refrigerants are crucial for the success of the system in the market place.
Normally these systems are constructed in an elementary manner, with each component existing independently in a closed loop, connected via piping. For larger ORCs, this is generally not an issue. The energy loss and added cost of complex piping networks is small relative to the overall power output/cost of the system. However, this is more of a concern for smaller ORCs, where the need to effectively package and assemble is crucial.
The compact torus-shaped ORC solves this by integrating all system components into a closed cylindrical can, where the working fluid flows about a torus in the poloidal direction. Both rotating devices (expander and pump) utilize a scroll type design. The evaporating and condensing processes are performed when the fluid is in transition between the two scroll devices. This lends to a more efficient and compact design, with a reduction in parts, system complexity and more secure refrigerant management.
The current paper includes a detailed description of the proposed design. The cycle is described starting with the expansion process and ending with the evaporation process with the function and implementation of each component described in detail along the way. The paper concludes with drawing a comparison in power consumption between current and proposed ORC systems.
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10:20
20 mins
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EXPERIMENTAL ACTIVITY ON THE COMPONENTS OF A DOMESTIC SCALE ORC COGENERATOR
Stefano Clemente, Diego Micheli, Mauro Reini, Robert Radu, Roberto Bracco, Giuseppe Toniato
Abstract: The Italian research program PIACE – Small Integrated and Adaptive Platform of High-Efficiency Micro-Cogeneration Units for Residential Use – is aimed to the development of several types of micro-CHP systems for domestic application. The authors are currently involved in the experimental tests of an ORC-based prototype, characterized by the following main features: very small scale (electric power up to 5 kWe), very low cost (using components derived from HVAC field), use of eco-friendly working fluids, capability to exploit low temperature heat sources such as flat solar collectors. Two different experimental activities have been completed up to now. The first one is the study of the behaviour of a gear pump operating on R245fa, the fluid chosen for the cogenerator [1]. The pump revealed good performances, despite the very low viscosity of the fluid, but some expedients had to be adopted in order to limit the leakage of R245fa towards ambient. The second activity has been the development, the construction and the conduction of the first field tests of an complete experimental prototype of an ORC micro-CHP unit [2]. The measurements revealed promising performances for the system, even if at the moment the latter has not been optimized yet: with a maximum cycle temperature of 130 °C and a minimum temperature of 40 °C, the recorded electric efficiency has been around 0.08, while values up to 0.12 are expected after the optimization. However, some operating limits have been detected on the current version of the prototype, mainly related to an unsuitable control of the vapour quality at the boiler outlet in some working conditions: the modifications needed to improve the system are then described in the conclusions of the work.
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10:40
20 mins
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INITIAL RESULTS AND EXPERIENCE FROM OPERATION OF LABORATORY SCALE CO2 RANKINE CYCLE
Maria Justo Alonso, Yves Ladam, Trond Andresen
Abstract: This work describes the small-scale setup (ROMA) installed at the SINTEF Energy Research/ NTNU (Norwegian University of Science and Technology) laboratory, designed to generate electricity from low temperature heat (120 ºC). The system operates a CO2 power cycle from a hot gas heat source with similar temperature to those of an aluminium production cell. The ROMA set-up was capable of producing up to 0.5 kW electrical power with a maximum turbine efficiency of 40 %. Laboratory test rig construction and results for prototype operation are presented in this paper.
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