Impact of the expander lubricant oil on the performance of the plate heat exchangers and the scroll expander in a micro-scale organic Rankine cycle system

Moradi, Ramin; Villarini, Mauro; Habib, Emanuele; Bocci, Enrico; Colantoni, Andrea; Cioccolanti, Luca

doi:10.1016/j.applthermaleng.2021.116714

Cited by 12 publications

(6 citation statements)

References 21 publications

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“…Among the parameters, the refrigerant miscibility of the refrigerant-oil mixture indicates how the oil moves in the system. In a two-phase mixture, the oil remains in its liquid phase due to its higher boiling point than the one of the refrigerant, and it enriches into the liquid refrigerant as the vapor quality increases [19]. Assuming that the oil is only mixed with the liquid refrigerant, the refrigerant-oil mixture would consist of gas refrigerant, liquid refrigerant, and lubricant, constituting a twophase three-component mixture.…”

Section: Experimental Procedures and Data Reductionmentioning

confidence: 99%

“…The above equation can be expressed in terms of refrigerant miscibility and OCR as shown below [19]:…”

Section: Experimental Procedures and Data Reductionmentioning

confidence: 99%

“…The mixture density is calculated using Equation ( 14) according to [19] to reconcile the calculated mass flow rate of the mixture using the measured volumetric flow rate. The coefficient K p is the density correction factor depending on the liquid temperature and its composition.…”

Section: Experimental Procedures and Data Reductionmentioning

confidence: 99%

“…The results for each scenario demonstrate a significant drop in the evaporator thermal power as the OCR increases. To quantify this, the capacity loss for the evaporator is obtained using the following equation [19], where . Q pure ev is the evaporator thermal power calculated using the pure refrigerant properties.…”

Section: Impact Of the Refrigerant-oil Mixture On The Evaporatormentioning

confidence: 99%

“…Their results showed the significant impact of lubrication on the system performance, which is more sensitive under the lower lubricant oil charges. Recently, some of the authors of the present paper [19] investigated the impact of the expander lubricant oil on the performances of the main components and especially of the scroll expander of a micro-scale ORC system. In their paper, a mixture of lubricant and refrigerant was travelling within the system components.…”

Section: Introductionmentioning

confidence: 99%

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Impact of the Lubricant on a Modified Revolving Vane Expander (M-RVE) in an Organic Rankine Cycle System

et al. 2023

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The expansion device is the critical component of micro-to-small scale organic Rankine cycle (ORC) systems, substantially affecting system efficiency and cost. Low isentropic efficiency and lubrication requirements are the main issues associated with using volumetric expanders in ORC systems. Despite lubrication contributing to reducing internal leakages in an expander, it may compromise the performance of the ORC system by adversely affecting the evaporator’s thermal capacity. This study tests a recently developed and modified revolving vane expander (M-RVE) in a micro-scale ORC test rig by implementing an adjustable oil mass flow rate. The impact of the lubricant oil on the performance of the M-RVE prototype is investigated within a wide range of oil circulation rates (OCR). The results demonstrate a negligible improvement in the filling factor for OCRs higher than 1%. Moreover, the shaft power is not considerably sensitive to OCR, while the calculated isentropic efficiency of the expander improves with OCR. Furthermore, the impact of the lubricant oil on the performance of the evaporator is studied, assuming the exact OCR as the expander and measured temperature and pressure similar to the pure refrigerant for the lubricant-refrigerant mixture in the evaporator. The study shows that the evaporator capacity is penalized with OCR, especially for values higher than 1%. Hence, an OCR of about 1% is a good compromise, and it can be used as a guideline for designing revolving vane expanders for micro-scale ORC systems without a dedicated lubricant oil circuit.

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Section: Experimental Procedures and Data Reductionmentioning

confidence: 99%

“…The above equation can be expressed in terms of refrigerant miscibility and OCR as shown below [19]:…”

Section: Experimental Procedures and Data Reductionmentioning

confidence: 99%

Section: Experimental Procedures and Data Reductionmentioning

confidence: 99%

Section: Impact Of the Refrigerant-oil Mixture On The Evaporatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%