Analysis of the intake process and its influence on the performance of a two-phase reciprocating expander

Wang, Qi; Wu, Weifeng; He, Zhilong; Ziviani, Davide

doi:10.1016/j.applthermaleng.2019.113943

Cited by 9 publications

(6 citation statements)

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“…In these scenarios, with high expander speeds and low heat source temperatures, the authors consider the screw expander to be more suitable. In [54], the authors develop a model for estimating these losses. This model is based on the intake ratio, as the temperature difference between the liquid and vapor phases mainly appears at the initial stage of the two-phase expansion process.…”

Section: Homogeneous Relaxation Modelmentioning

confidence: 99%

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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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Section: Homogeneous Relaxation Modelmentioning

confidence: 99%

“…Ref. [54] used this design with the model of [47] to estimate the intake losses. For this design, the authors found a linear relation between the intake losses and the intake ratio, defined as the intake time to the expansion time.…”

Section: Reciprocating Expandermentioning

confidence: 99%

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

2022

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“…The TFC proposed by Smith et al in 1993 11 was considered the cycle with the best temperature matching due to its 100% single‐phase heating process. Therefore, for the low‐temperature heat recovery, the TFC showed great potential in obtaining high system efficiencies 25 . For instance, Yari et al 26 conducted a comparison study of the thermo‐economic performance of the TFC, ORC, and Kalina cycle.…”

Section: Introductionmentioning

confidence: 99%

“…However, it was also concluded that the thermo‐economic performance of the TFC was strongly affected by the isentropic efficiency of the two‐phase expander. It should be emphasized that the expansion process in the TFC expander is a two‐phase flash expansion whose thermodynamic characteristics differ significantly from the conventional gas expansion 25 . According to the papers of Bianchi et al 27 and Wang et al, 28 a major problem with the TFC is the design and manufacture of a reliable and efficient two‐phase expander, which greatly limits the applications of this technology.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, for the low-temperature heat recovery, the TFC showed great potential in obtaining high system efficiencies. 25 For instance, Yari et al 26 conducted a comparison study of the thermo-economic performance of the TFC, ORC, and Kalina cycle. It was found that under a low-temperature heat source of 120°C, the TFC could achieve a larger net power output than both the ORC and Kalina cycle.…”

Section: Introductionmentioning

confidence: 99%

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Analysis and assessment of a novel organic flash Rankine cycle (OFRC) system for low‐temperature heat recovery

Wang

Macián‐Juan

2022

Energy Science & Engineering

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In this paper, a novel organic flash Rankine cycle (OFRC) system for lowtemperature heat recovery is analyzed and optimized using the 3E (energy, exergy, and economic) analysis method and particle swarm optimization algorithm, respectively. Five environmentally friendly organic fluids and three typical heat source conditions are simultaneously discussed during the parametric analysis and optimization process, to obtain a comprehensive understanding of the thermo-economic characteristics of this novel system.The main analysis results show that the biggest exergy loss of the OFRC system is caused by the condenser, followed by the evaporator. About 70% of the specific power cost is caused by the capital investment of the system, and more than 60% of the capital investment is spent on purchasing the highpressure and low-pressure expanders. Under the same operating conditions, the working fluids with high critical temperatures can achieve higher cycle thermal efficiency and lower specific power costs than those with low critical temperatures. The optimization results show that the OFRC system is able to achieve a better thermodynamic performance than the organic Rankine cycle (ORC) and organic flash cycle (OFC) systems, and when the heat source's inlet temperature is set to 100°C, 120°C, and 140°C, R245fa, R290, and R152a are, respectively, recommended as the best working fluid for the OFRC system.Besides this, it is found that the OFC system has the worst thermo-economic performance, and the ORC system can achieve the lowest specific power cost.A new finding is that, for all three systems, the higher the critical temperature of the working fluid, the lower the specific power cost of the system.

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