Experimental characterization of a hermetic scroll expander operating in an ORC-based power unit bottoming an internal combustion engine

Fatigati, Fabio; Bartolomeo, Marco Di; Battista, Davide Di; Cipollone, Roberto

doi:10.1063/1.5138802

Cited by 13 publications

(14 citation statements)

References 18 publications

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“…An optimized model of the ORC section is employed to reproduce the operation of the power unit, based on the approach discussed in [30,34], adapted to the situation where a scroll expander is used. The ORC-unit map that comes out is in good agreement with the experimental data in [37], where the potential of an ORC-unit, featuring a scroll expander and a volumetric pump as the rotary equipment, R245fa as the working fluid and performing heat recovery on a 90 °C-to-120 °C heat source is considered. Some of the operating points of the ORC unit can be found in Table 3.…”

Section: Control Strategysupporting

confidence: 70%

“…Such an efficiency gain is extremely appealing in small scale systems, where a high back-work ratio (i.e. ratio between the work for pumping and the work gathered at the expander) usually applies and ends up questioning the plant feasibility [34,37]. These features represent an added value for the ORC system, particularly in presence of an upper thermal source characterized by unsteady heat availability and highly variable thermodynamic conditions like those proper of a domestic solar CHP application (i.e.…”

Section: Combined Heat and Power System Modelingmentioning

confidence: 99%

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Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

et al. 2020

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The feasibility of a solar-ORC system for domestic combined heat and power generation (CHP) is deeply affected by both the time-varying ambient conditions (e.g. solar irradiance, temperature, wind speed) and the thermal and electrical load profiles variability of the final application. The definition of a proper control strategy is proven to be a major design-challenge for successful operation of solar-ORC systems, with the main goal of assuring that the thermal power demand for space heating and Domestic Hot Water (DHW) production and the electricity needs are simultaneously satisfied. The rising demand for energy-autonomous systems also calls for the inclusion of a storage system within the base-layout, that could assure the electricity demand is properly matched after sunset or in very-low irradiance conditions, such as cloudy days. A comprehensive model accounts for the dynamic of the plant-integrated unit, featuring an ORC-based plant that bottoms a flat plate solar thermal collector: a parametric study is presented, and an off-design analysis is performed to properly assess the energy performance of the system. The heat availability to the ORC heat exchanger is evaluated, based on solar availability, thermal losses in the pipes and plant requirements, in terms of operating temperature and pressures and organic fluid mass flowrate. R245fa is selected as working fluid in the ORC-section. Sliding vanes machines expander and pump – are considered as rotary equipment. Flat plate heat exchangers complete the base layout, the analysis accounts for. Due to the need for DHW production, a storage unit for hot water is present, upstream the recovery branch: dependently on the ability the fluid at the collector outlet has to meet the ORC requirements for proper operation (about 110°C), the ORC evaporator is fed and the recovery section enabled. Both continuous and unsteady operation underwent an in-depth analysis, as well as the benefits associated with different discharge times for the storage unit. A dedicated control strategy is defined, dependently on whether the electrical output or the thermal one need to be maximized, and accounts for either a flash or a progressive tank discharge. A virtual platform allowed the setting-up of a pilot plant, for direct performance assessment, in presence of different amounts of tank discharges per day and different lower temperatures at the storage tank.

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Section: Control Strategysupporting

confidence: 70%

Section: Combined Heat and Power System Modelingmentioning

confidence: 99%

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

et al. 2020

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“…Furthermore, the ORC plant developed and reported in Ref. [56] adopting a single-screw expander was demonstrated to have an efficiency of up to 6.3%, while the expander reached an efficiency of 58%, and an ORC plant recovering heat from a 3-L diesel engine reached an efficiency of up to 4% when employing a scroll expander [53]. In the application considered in Ref.…”

Section: Further Discussionmentioning

confidence: 96%

“…In addition to the selection of a proper volumetric efficiency for the expander, a second possibility for performance enhancement comes from the pump optimization, in order to reduce the BWR [51] or from the adoption of a less permeable expander [53]. In the case at hand, half the power produced by the expander is consumed by the pump.…”

Section: Orc-based Power Plant Performance Optimization Strategiesmentioning

confidence: 99%

Design and Operational Control Strategy for Optimum Off-Design Performance of an ORC Plant for Low-Grade Waste Heat Recovery

et al. 2020

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The applicability of organic Rankine cycle (ORC) technology to waste heat recovery (WHR) is currently experiencing growing interest and accelerated technological development. The utilization of low-to-medium grade thermal energy sources, especially in the presence of heat source intermittency in applications where the thermal source is characterized by highly variable thermodynamic conditions, requires a control strategy for off-design operation to achieve optimal ORC power-unit performance. This paper presents a validated comprehensive model for off-design analysis of an ORC power-unit, with R236fa as the working fluid, a gear pump, and a 1.5 kW sliding vane rotary expander (SVRE) for WHR from the exhaust gases of a light-duty internal combustion engine. Model validation is performed using data from an extensive experimental campaign on both the rotary equipment (pump, expander) and the remainder components of the plant, namely the heat recovery vapor generator (HRVH), condenser, reservoirs, and piping. Based on the validated computational platform, the benefits on the ORC plant net power output and efficiency of either a variable permeability expander or of sliding vane rotary pump optimization are assessed. The novelty introduced by this optimization strategy is that the evaluations are conducted by a numerical model, which reproduces the real features of the ORC plant. This approach ensures an analysis of the whole system both from a plant and cycle point of view, catching some real aspects that are otherwise undetectable. These optimization strategies are considered as a baseline ORC plant that suffers low expander efficiency (30%) and a large parasitic pumping power, with a backwork ratio (BWR) of up to 60%. It is found that the benefits on the expander power arising from a lower permeability combined with a lower energy demand by the pump (20% of BWR) for circulation of the working fluid allows a better recovery performance for the ORC plant with respect to the baseline case. Adopting the optimization strategies, the average efficiency and maximum generated power increase from 1.5% to 3.5% and from 400 to 1100 W, respectively. These performances are in accordance with the plant efficiencies found in the experimental works in the literature, which vary between 1.6% and 6.5% for similar applications. Nonetheless, there is still room for improvement regarding a proper design of rotary machines, which can be redesigned considering the indications resulting from the developed optimization analysis.

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“…Many researchers employ a scroll pair and Lee. et.al (Lee & Wu, 1996) conducted a study on several theorems relating to planar orbiting processes (Fatigatib, 2020).…”

Section: Cad Modeling Of a Scroll Geometrymentioning

confidence: 99%

Numerical and Experimental Investigation of Nonlubricated Air Scroll Expander Derived From a Refrigerant Scroll Compressor

Konijeti¹,

Kottapalli²

2022

Front. Heat Mass Transf.

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additional advantages when it comes to replacing equipment in automobiles for smooth, frictionless operation (Fatigati et al., 2022). They can also work in both dry and wet conditions, which is useful in heat-generating applications.The operation of the scroll machine is very simple and makes its simplicity a major factor in many industries. The other factors like compactness and durability are the added advantages of the scroll machine. These factors make it a viable choice as an expander in various industries including small-scale ORC systems (Fatigatib, 2020). The scroll expander was divided into three major categories like hermetic scroll-type expanders, semi-hermetic scroll-type expanders, and open scroll-type expander drive expanders were studied in the literature study done by Fatigatib (Fatigatib, 2020) in the year 2020. A review by Fatigatib (Fatigatib, 2020) , studied a small-scale ORC-based test bench. The working fluid considered in the study is R134a for debuting a hermetic scroll expander. The scroll-type expander used in the study is derived from a compressor and used three poles asynchronous engine for integrating the hermetic scroll-type expander developed. Literature ReviewScroll expander application in the automobile industry has been tested (Fatigati et al., 2022). In this research, the scroll expander's feasibility as a dual intake port is analyzed. Similarly, research on a large number of micro-to small-scale organic Rankine cycle (ORC) applications are Frontiers in Heat and Mass Transfer

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Experimental characterization of a hermetic scroll expander operating in an ORC-based power unit bottoming an internal combustion engine

Cited by 13 publications

References 18 publications

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

Multi-Variable Control and Optimization Strategy for Domestic Solar-ORC Combined Heat and Power Generation System

Design and Operational Control Strategy for Optimum Off-Design Performance of an ORC Plant for Low-Grade Waste Heat Recovery

Numerical and Experimental Investigation of Nonlubricated Air Scroll Expander Derived From a Refrigerant Scroll Compressor

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