A comparison of heat transfer correlations applied to an Organic Rankine Cycle

Calise, Francesco; Macaluso, Adriano; Pelella, Pasquale; Vanoli, Laura

doi:10.1016/j.jestch.2018.09.009

Cited by 8 publications

(6 citation statements)

References 25 publications

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“…The Organic Rankine Cycle (ORC), which emerges as a particularly well-suited technology for low temperature and small-scale applications, is considered for electrical energy production [11]. A scheme of the layout is illustrated in Figure 1.…”

Section: Energy Modelmentioning

confidence: 99%

Low enthalpy geothermal source for sustainable energy production in small islands: a real case study

Fraia,

Massarotti,

Vanoli

2024

J. Phys.: Conf. Ser.

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The global demand for clean and sustainable energy sources has significantly increased in recent years, mainly because of concerns about climate change and the finite nature of traditional fossil fuel reserves. In this context, geothermal energy has gained significant attention as a reliable and eco-friendly alternative. In particular, low enthalpy geothermal resources have emerged as an attractive option due to their accessibility, widespread distribution, and potential for decentralization. Moreover, reliability and flexibility of this source allow for year-round utilization to meet diverse energy demands, resulting in reduced dependency on traditional energy sources and associated greenhouse gas emissions. For this reason, geothermal energy appears to be a promising solution in small islands, where energy production is often a challenge due to the absence of infrastructures that make them energy-dependent on the mainland. Therefore, in this work, low enthalpy geothermal source is considered as effective and sustainable solution for electrical energy production in small islands. As case study a low temperature source available in Ischia island, Southern Italy, is considered. The proposed solution is analysed from energy, economic and environmental point of view.

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Section: Energy Modelmentioning

confidence: 99%

Low enthalpy geothermal source for sustainable energy production in small islands: a real case study

Fraia,

Massarotti,

Vanoli

2024

J. Phys.: Conf. Ser.

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“…Also, the HTCs achieved in this work on the working fluid side are in the range of 900-2,500 W/m 2 K (for the singlephase zones in the evaporator heat exchanger), and may exceed 3,000 W/m 2 K in the two-phase zone, which aligns well with the data reported in the literature, in Refs. [8,46,50]. The Chen-Zuber [42,48] correlation is presented in Appendix A.…”

Section: Evaporatormentioning

confidence: 99%

Off-design optimisation of organic Rankine cycle (ORC) engines with piston expanders for medium-scale combined heat and power applications

et al. 2019

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Organic Rankine cycle (ORC) engines often operate under variable heat-source conditions, so maximising performance at both nominal and off-design operation is crucial for the wider adoption of this technology. In this work, an off-design optimisation tool is developed to predict the impact of varying heat-source conditions on ORC operation. Unlike previous efforts where the performance of ORC engine components is assumed fixed, here we consider explicitly the time-varying operational characteristics of these components. A bottoming ORC system is first optimised for maximum power output when recovering heat from the exhaust gases of an internal-combustion engine (ICE) running at full load. A double-pipe heat exchanger (HEX) model is used for sizing the ORC evaporator and condenser, and a piston expander model for sizing the expander. The ICE is then run at part-load, thus varying the temperature and mass flow rate of the exhaust gases. The tool predicts the new off-design heat transfer coefficients in the heat exchangers, and the new optimum expander operating points. Results reveal that the ORC engine power output is underestimated by up to 17% when the off-design operational characteristics of these components are not considered. In particular, the piston expander isentropic efficiency increases at off-design operation by 10-16%, due to the reduced pressure ratio and flow rate in the system, while the evaporator effectiveness improves by up to 15%, due to the higher temperature difference across the HEX and a higher proportion of heat transfer taking place in the two-phase evaporating zone. As the ICE operates further away its nominal point, the offdesign ORC engine power output reduces by a lesser extent than that of the ICE. At an ICE part-load operation of 60% (by power), the optimised ORC engine with fluids such as R1233zd operates at 77% of its nominal capacity. ORC off-design performance maps are generated, predicting system performance and can be used by ORC system designers, manufacturers and plant operators to identify optimum performance under real operating conditions.

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“…The general information regarding ORC applications can be found in [23][24][25][26]. Similarly, the research regarding working fluids can be sought from [27][28][29] and, regarding components, from [30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Integrated Vapor Compression Chiller with Bottoming Organic Rankine Cycle and Onsite Low-Grade Renewable Energy

et al. 2021

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The present study offers a scheme to improve the performance of existing large-scale chillers. The system involves raising the temperature of the chiller’s cooling water stream using renewable energy sources by incorporating an organic Rankine cycle (ORC). The thermal analysis was conducted by raising the temperature of one-third of the approximately 200 ton chiller’s cooling water. The investigation was considered for ORC evaporator inlet temperature of 90~120 °C by the step of 10 °C. Various working fluids for the different ORC evaporator inlet temperatures were examined. Sensitivity analyses conducted on the degree of superheating, degree of subcooling, condenser saturation temperature, pinch point temperature differences of the ORC evaporator and condenser, and the mass flowrates of the heating and cooling streams were also reported. Genetic algorithm was employed to carry out the optimization. The best options for the ORC working fluid at the heating source ORC evaporator inlet temperatures of 90 °C was found to be DME, presenting an improvement of 48.72% in comparison with the rated coefficient of performance (COP) value of the VCC, with a renewable energy input requirement of 710 kW. At the heat source temperatures of 100 °C and 110 °C, butene, which presented an improvement in the COP equal to 48.76% and 68.85%, respectively, with the corresponding renewable energy requirements of 789.6 kW and 852 kW, was found to be the ideal candidate. Meanwhile, at the heat source inlet temperature of 120 °C, R1233zd (E), representing an improvement of 140.88% with the renewable energy input of around 1061 kW, was determined to be the most favorable ORC working fluid candidate.

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A comparison of heat transfer correlations applied to an Organic Rankine Cycle

Cited by 8 publications

References 25 publications

Low enthalpy geothermal source for sustainable energy production in small islands: a real case study

Low enthalpy geothermal source for sustainable energy production in small islands: a real case study

Off-design optimisation of organic Rankine cycle (ORC) engines with piston expanders for medium-scale combined heat and power applications

Integrated Vapor Compression Chiller with Bottoming Organic Rankine Cycle and Onsite Low-Grade Renewable Energy

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