Small-scale Organic Rankine cycles (ORCs) are recognized as a promising solution to recover thermal energy from internal combustion engines (ICEs) in the transportation field, especially onboard of innovative longhaul trucks. Design methods for ORCs typically aim at obtaining good performance at both design and offdesign operating conditions, especially in the frequent case of variable heat source flow rate and temperature. The fluid dynamic design of ORC turbines, whose performance considerably impacts on cycle efficiency, is usually performed by exploiting meanline models to define a baseline geometry, followed by the application of CFDbased shape optimization techniques. However, the validation of both low and highfidelity tools is limited, due to a lack of experimental data. To fill this gap, an experimental campaign on supersonic ORC nozzle cascade was started at Politecnico di Milano. This paper comprehensively describes the methodologies applied to setup an innovative linear cascade experiment, representative of the stator operation of axial/radial turboexpanders for ORC systems. The selected working fluid is siloxane MM. Due to the nature of the flow, which feature complex shock patterns, and to the intrinsic challenge of performing measurements in closetocritical point regions, several issues need to be solved to properly setup the experiments. Cascade operating conditions to be investigated during the experiments are reported, as well as the methodology to setup the test section, namely blade number, stagger angle, blade and side wall profiles. Main objective of experiments is to retrieve nozzle total pressure losses, in order to have a first validation of numerical simulations in terms of entropy production. A relatively high space resolution for measuring points is obtained downstream the cascade. Measurement technique selected include supersonic total pressure probes and wall pressure taps, as well as thermocouples and schlieren visualization. This paper reviews all steps required to design the campaign and aims at serving as a reference for future experimental investigations on ORC cascades. Main result of this preliminary work is the implementation of a relatively simple methodology to carry out experiments in blade cascade operated with organic vapors and aimed at evaluating row losses, without resorting to specifically calibrated instrumentation.
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Small-scale Organic Rankine cycles (ORCs) are recognized as a promising solution to recover thermal energy from internal combustion engines (ICEs) in the transportation field, especially onboard of innovative longhaul trucks. Design methods for ORCs typically aim at obtaining good performance at both design and offdesign operating conditions, especially in the frequent case of variable heat source flow rate and temperature. The fluid dynamic design of ORC turbines, whose performance cons...
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