Modelling and off-design performance optimisation of a trilateral flash cycle system using two-phase twin-screw expanders with variable built-in volume ratio

Bianchi, Giuseppe; Marchionni, Matteo; Miller, Jeremy; Tassou, Savvas A.

doi:10.1016/j.applthermaleng.2020.115671

Cited by 25 publications

(7 citation statements)

References 27 publications

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“…Zivinani et al [147] presented that the friction losses played a major role in the total loss of a SSE followed by suction pressure drops and leakages, based on a semi-empirical model. Optimizing the built-in volume ratio is also important to improve the expander performance by reducing under-expansion or over-expansion losses [148,149]. Wu et al [150] concluded that the optimal built-in volume ratio was not the bigger the better when SSE worked at high pressure ratio condition, because suction pressure loss also increased with the increase of built-in volume ratio.…”

Section: Orc Systemmentioning

confidence: 99%

“…The [104] further presented that adopting slide valves can effectively improve the power output of the SSE and the net power output of the ORC system. Bianchi et al [149]. Lei et al [151] proposed that introducing exhaust kinetic energy utilization process in SSE can reduce under-expansion losses effectively, and the effects in large size expanders were stronger than that in small scale machines.…”

Section: Orc Systemmentioning

confidence: 99%

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A Review of Recent Research and Application Progress in Screw Machines

Wang

Liu

et al. 2022

Machines

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Screw machines, mainly including single-screw type and twin-screw type, have gone through significant development and improvement during the past decade. This paper reviews the relevant studies available in the open literature for acquiring insight into and to establish the state of the art of the research and application status of screw machines. The related research on different aspects, which would affect the performance and reliability of screw machines includes rotor profile and geometric characteristics, thermodynamic modelling, vibration and noise, lubrication and wear, control of capacity and built-in volume ratio, and liquid injection technology. In the aspect of thermodynamic modelling, the available methods, i.e., empirical or semi-empirical model, lump model, and 3D CFD model, adopted for the performance prediction and optimal design of screw machines are summarized. Then, the review covers the application status of screw machines in the fields of air compression and expansion, refrigeration and heat pump, organic Rankine cycle (ORC), and other popular applications, with an emphasis on the reported performance and progress in technologies of screw machines. Finally, conclusions and perspectives for future research in the area of screw machines are presented. The review provides readers with a good understanding of the research focus and progress in the field of screw machines.

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Section: Orc Systemmentioning

confidence: 99%

Section: Orc Systemmentioning

confidence: 99%

A Review of Recent Research and Application Progress in Screw Machines

Wang

Liu

et al. 2022

Machines

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“…The authors found a significant impact of the intake manifold expansion on the overall machine performance. Therefore, the authors designed a Lysholm expander with a variable built-in volume ratio [67]. The simulations show higher total power outputs for smaller BVR due to the higher mass flow rates, while the specific power decreases.…”

Section: Lysholm Expandermentioning

confidence: 99%

Two-Phase Volumetric Expanders: A Review of the State-of-the-Art

2022

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Two-phase expansion is the process where a fluid undergoes a pressure drop through or in the liquid–vapor dome. This operation was historically avoided. However, currently it is studied for a multitude of processes. Due to the volume increase in volumetric expanders, a pressure drop occurs in the fluid resulting in flashing phenomena occurring. These phenomena have been studied before in other processes such as two-phase flows or static flash. However, this has not been extensively studied in volumetric expanders and is mostly neglected. Even if data has shown this is not always neglectable depending on the expander type. The thermal non-equilibrium occurring can be modeled on different principles of flashing flows, such as the mixture model, boiling delay model, and homogeneous relaxation model. The main application area in current literature for volumetric two-phase expansion machines, is in low-temperature two-phase heat-to-power cycles. These cycles have shown benefit over classic options if expanders are available with efficiencies in the range of at least 75%. Experimental investigation of expanders in two-phase operation, though lacking in quantity, has shown that this is an achievable goal. However, the know-how to accomplish this requires more studies, both experimentally and in modeling techniques for the different phenomena occurring within these expanders. The present work provides a brief but comprehensive overview of the available experimental data, applicable flashing modeling techniques, and available models of volumetric two-phase expanders.

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“…The heat transfer Q ̇ex (with the index ex referring to the exhaust side) between fluid and compressor housing after the compression steps is modeled equivalent to the suction warming in equation (3). However, the model parameter UAex,nom is used in equation ( 4) to determine the corresponding heat transfer coefficient.…”

Section: Base Model From the Literaturementioning

confidence: 99%

“…The assessment of processes utilizing variable-BVR machines requires reliable models, which are also valid in the part-load region. However, existing modeling approaches for twin-screw machines are unable to reproduce the effects of a varying BVR or require extensive knowledge of the machine geometry [3], which is often not available. This work extends an existing semiempiric twin-screw compressor model from Giuffrida [4] in order to account for a varying BVR.…”

Section: Introductionmentioning

confidence: 99%