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Session: Parallel Session: System Design, Optimization and Applications Ime
Session starts: Thursday 22 September, 11:10
Presentation starts: 11:30
Room: Senaatszaal

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Jean-François Oudkerk (ULg)
Sylvain Quoilin (ULG)
Vincent Lemort (Ulg)

Abstract:
The Organic Ranking Cycle (ORC) is often considered as a suitable technology for micro Combined Heat and Power (CHP): the ORC unit can indeed be associated with a boiler to produce heat (at the condenser of the cycle) and electricity (at the expander). The advantages of this technology are a high reliability and simple maintenance and a large fuel flexibility because of the external combustion. For micro-CHP units (i.e a few kWe), scroll machines are often preferred to turbomachines as expansion device because of their low cost, simplicity, low rotating speed and their capacity to handle high pressure ratios. Moreover, scroll compressors do not require much adaption to work in expander mode. This paper aims to evaluate the performance and profitability of an ORC-based micro-CHP system. It focuses more particularly on the use of a hermetic scroll compressor used as expander in the ORC. The first part of the paper describes the design and the performance of a prototype of hermetic scroll expander (compressor adapted to work in expander mode), tested into a gas cycle test rig with R245fa as working fluid. A semi empirical model using a limited number of physical meaning parameters is then built and validated with the experimental results. In the second part of the paper, this model is inserted into an ORC model and coupled with a boiler model. With this global model, three systems configuration are evaluated in term of electrical and thermal efficiencies and the best one is selected. Once the best configuration is determined, the operation of the system is simulated on a full year in order to evaluate the seasonal performance of the ORC-based micro CHP system. Using economical criteria such as net present value and levelized electricity cost, the profitability of the system is evaluated. Parametric studies are performed on the profitability varying several parameters like discount rate, price of fuel, subsidies… Finally, adaptations of the hermetic scroll compressor are proposed to improve the efficiency of the system.