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Design of a two-phase reciprocating expansion test-rig for model validation.

Number: 1263

Author(s) : VAN HEULE X., VIEREN E., PAEPE M. de, LECOMPTE S.

Summary

Two-phase expansion processes have gathered increased interest over the past years. Possible applications are found in conversion of low-grade heat to power, ranging from solar and geothermal heat to automotive and industrial waste heat. Currently, these applications make use of the basic Organic Rankine Cycle (ORC) concept. However, theoretical studies of two-phase cycles, such as the Trilateral cycle (TLC) and the Partial Evaporation Organic Rankine Cycle (PEORC), show efficiency improvements of over 15% compared to the basic ORC. Two-phase expansion is also beneficial in heat pumps. Substituting the classical throttle valve with a two-phase expansion device allows a COP increase by 7 to 10%. Yet, the fundamentals of two-phase liquid-vapor expansion are not fully understood. Hence, there are no effective guidelines to design two-phase expanders. During the rapid expansion in the two-phase region, the two-phase mixture goes through various thermodynamic non-equilibrium states. These non-equilibrium states are marked by a mixture consisting of saturated vapor and superheated liquid at saturation pressure. This makes the actual prediction of the flashing evaporation rate challenging. In previous work by the authors, the evaporation rate of the mixture was predicted by a Homogeneous Relaxation Model (HRM). In this study, an experimental test rig is presented which is capable to expand two-phase refrigerants in representative working conditions. The goal is to measure the pressure and temperature profiles during expansion. With this unique dataset, the predictive model will be calibrated and validated in future work.

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  • Original title: Design of a two-phase reciprocating expansion test-rig for model validation.
  • Record ID : 30030295
  • Languages: English
  • Subject: Technology
  • Source: 2022 Purdue Conferences. 26th International Compressor Engineering Conference at Purdue.
  • Publication date: 2022/07/15

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