Organic Rankine cycle receiver development

The selected receiver concept is a direct-heated, once-through, monotube boiler operated at supercritical pressure. The cavity is formed by a cylindrical copper shell and backwall, with stainless steel tubing brazed to the outside surface. This core is surrounded by lightweight refractory insulation, load-bearing struts, and an outer case. The aperture plate is made of copper to provide long life by conduction and reradiation of heat away from the aperture lip. The receiver thermal efficiency is estimated to be 97 percent at rated conditions (energy transferred to toluene divided by energy incident on aperture opening). Development of the core manufacturing and corrosion protection methods is complete

Techno-economic analysis of combined inverted Brayton – Organic Rankine cycle for high-temperature waste heat recovery

Many practical cases with waste heat recovery potential such as exhaust gases of reciprocating engines, cement kilns or heat-treating furnaces, are nowadays often integrated with organic Rankine cycle to convert waste heat to the mechanical power. However, when dealing with high-temperature waste heat, organic Rankine cycle faces efficiency limit due to the physical properties of the working and thermal fluids. That gives room for further enhancement of the waste heat recovery technologies via the investigation of different non-conventional schemes as one of the possible ways. In the present work, a system introducing the combined inverted Brayton plus organic Rankine cycle is under investigation. Aspen Hysys models of both conventional organic Rankine cycle and combined cycle were designed, orienting on waste heat recovery from the heavy-load gas-fueled reciprocating engine exhaust. In this way, the performance of the combined scheme was benchmarked versus the conventional organic Rankine cycle. An assessment of the organic Rankine cycle working fluids was provided, and pentane has shown the best thermodynamic performance. The study on inverted Brayton cycle defined the remarkable effect of the water condensation in the gas duct on the inverted Brayton cycle performance. Finally, both thermodynamic and economic optimizations of the models were conducted, setting the stage for the comparison of solutions. Results have shown the 10% advantage of the combined scheme over organic Rankine cycle in generated power and system efficiency. The levelized-cost-of-energy-based optimization for variable capacity factors has highlighted above 6% advantage of the investigated solution. The analysis of the sensitivity from machines' efficiencies and heat exchangers' pinches has shown that with some sets of parameters, the studied scheme may concede to the organic Rankine cycle. Keywords: Inverted Brayton cycle, Organic Rankine cycle, Waste heat recovery, High-temperature exhaust, Techno-economic analysi

Mathematical modelling of operation modes and performance evaluation of an innovative small-scale concentrated solar organic Rankine cycle plant

In this paper an innovative small-scale concentrated solar 2 kWe organic Rankine cycle plant coupled with a phase change material storage tank equipped with reversible heat pipes is investigated using a simulation analysis. The plant, intended for residential applications, is going to be built and tested under the European funded H2020 Innova MicroSolar project executed by the consortium of several Universities and industrial organizations, led by Northumbria University. The authors of this work used the design of the integrated system, developed by the consortium, to preliminary estimate the overall performance of the system in order to provide useful information for its forthcoming real operation. In particular, according to the varying ambient conditions, the influence of different operation modes of the prototype plant are evaluated. The dynamic simulation analysis has shown an interesting performance of the system in terms of annual operating hours, power production and conversion efficiencies. More precisely, the organic Rankine cycle unit is able to operate for more than 3100 h/year, achieving the design performance when solar power is sufficiently high, producing about 5100 kWhe/year. For the considered operating set-point temperatures of the thermal energy storage, the plant is able to reach high conversion efficiency also when the organic Rankine cycle unit is supplied by discharging the energy stored in the storage tank, for about 800 h/year. Hence, the work has provided some useful insights into the best working conditions of such micro combined heat and power system to be integrated in residential buildings. Moreover, the analysis could serve as a general guide for the design and optimization of the mutual interactions of the different subsystems in small-scale concentrated solar organic Rankine cycle plants

Modelling, simulation and comparison of phase change material storage based direct and indirect solar organic Rankine cycle systems

The thermodynamic performance of a novel direct solar organic Rankine cycle system and conventional indirect solar organic Rankine cycle system is compared in this study. The working fluid is vaporized directly in the solar collectors in direct solar organic Rankine cycle system while heat transfer fluid is used to vaporize the working in indirect solar organic Rankine cycle system. The evacuated flat plate collectors array covering a total aperture area of 150 m2 is employed as a heat source and a phase change material tank having a surface area of 25.82 m2 is used as thermal storage for both configurations. R245fa and water are chosen as heat transfer fluids for direct and indirect solar organic Rankine cycle systems, respectively. However, R245fa is used as a working fluid for both configurations. The performance of both configurations is compared by carrying out weekly, monthly and annual dynamic simulations in MATLAB by using hourly weather data of Islamabad, Pakistan. The direct solar organic Rankine cycle system outperforms the indirect solar organic Rankine cycle system in terms of thermal efficiency and net power. The annual system efficiency and an annual average net power of the direct solar organic Rankine cycle system are 71.96% and 64.38% higher than indirect solar organic Rankine cycle system respectively. However, average annual heat stored by phase change material during charging mode of indirect solar organic Rankine cycle system is 4.24 MJ more than direct solar organic Rankine cycle system. Conversely, direct solar organic Rankine cycle system has provided annual daily average power of 33.80 kW extra to heat transfer fluid during the discharging mode of phase change material storage. Furthermore, with phase change material storage, the capacity factor is increased by 17 % and 21.71 % on annual basis for direct and indirect solar organic Rankine cycle systems, respectively

A Comparison of Organic and Steam Rankine Cycle Power Systems for Waste Heat Recovery on Large Ships

This paper presents a comparison of the conventional dual pressure steam Rankine cycle process and the organic Rankine cycle process for marine engine waste heat recovery. The comparison was based on a container vessel, and results are presented for a high-sulfur (3 wt %) and low-sulfur (0.5 wt %) fuel case. The processes were compared based on their off-design performance for diesel engine loads in the range between 25% and 100%. The fluids considered in the organic Rankine cycle process were MM(hexamethyldisiloxane), toluene, n-pentane, i-pentane and c-pentane. The results of the comparison indicate that the net power output of the steam Rankine cycle process is higher at high engine loads, while the performance of the organic Rankine cycle units is higher at lower loads. Preliminary turbine design considerations suggest that higher turbine efficiencies can be obtained for the ORC unit turbines compared to the steam turbines. When the efficiency of the c-pentane turbine was allowed to be 10% points larger than the steam turbine efficiency, the organic Rankine cycle unit reaches higher net power outputs than the steam Rankine cycle unit at all engine loads for the low-sulfur fuel case. The net power production from the waste heat recovery units is generally higher for the low-sulfur fuel case. The steam Rankine cycle unit produces 18% more power at design compared to the high-sulfur fuel case, while the organic Rankine cycle unit using MM produces 33% more power

The study of a seasonal solar cchp system based on evacuated flat-plate collectors and organic rankine cycle

The demands of cooling, heating and electricity in residential buildings are varied with seasons. This article presented a seasonal solar combined cooling heating and power (CCHP) system based on evacuated flat-plate collectors and organic Rankine cycle. The heat collected by evacuated flat-plate collectors is used to drive the organic Rankine cycle unit in spring, autumn and winter, and drive the double-effect lithium bromide absorption chiller in summer. The organic Rankine cycle condensation heat is used to yield hot water in spring and autumn, whereas supply heating in winter. The system thermodynamic performance was analyzed. The results show that the system thermal efficiency in spring, autumn and winter, ηsys, I, increases as organic Rankine cycle evaporation temperature, T6, and evacuated flat-plate collectors outlet temperature, T2, decrease. The maximum ηsys, I of 67.0% is achieved when T6 = 80 °C and T2 =100 °C. In summer, the system thermal efficiency, ηsys, II, increases first and then decreases with the increment of T2. The maximum ηsys, II of 69.9% is obtained at T2 =136 °C. The system output performance in Beijing and Lanzhou is better than that in Hefei. The average output power, heating capacity, hot water and cooling capacity are 50-72 kWh per day, 989-1514 kWh per day, 49-57 ton per day and 1812-2311 kWh per day, respectively. The system exergy efficiency increases from 17.8-40.8% after integrating the organic Rankine cycle unit

ORCSim: a generalized Organic Rankine cycle simulation tool

An increasing interest in organic Rankine cycle (ORC) technology has led to numerous simulation and optimization studies. In the open-literature different modeling approaches can be found, but general software tools available to the academic/industrial community are limited. A generalized ORC simulation tool, named ORCSim, is proposed in this paper. The framework is developed using object-oriented programming that easily allows improvements and future extensions. Currently two cycle configurations are implemented, i.e. a basic ORC and an ORC with liquid-flooded expansion. The software architecture, the thermo-physical property wrappers, the component library and the solution algorithm are discussed with particular emphasis on the ORC with liquid-flooded expansion. A thorough validation both at component and cycle levels is proposed by considering the aforementioned cycle architectures

Investigation of Organic Rankine Cycle Using Different Working Fluids for Conversion of Low Grade Heat Sources

This research paper entitled Investigation of Organic Rankine Cycle using different working fluids for conversion of low grade heat sources, is studied in Final Year Project I and Final Year Project II. This paper is reviewed on type of Rankine cycles that produces electrical power of heat sources, including conventional Rankine cycle and especially organic Rankine cycle. Water as the common working fluid for Rankine cycle when the heat input is from high grade heat sources, example coal and fuel. High molecular weight working fluids example, R22, R134a and R141b are ideal for Organic Rankine Cycle, this is because is boiling point of those working fluids are relatively very smaller compared to water. Besides that, ORC uses low grade heat sources like, solar and waste heat energy. The main purpose of this research project is to identify suitable organic working fluid which gives better work net, back work ratio and efficiency

An organic Rankine receiver for the SCSTPE program

The organic Rankine cycle receiver which is presently being developed is described. The receiver employs an integrated cavity/pool boiler which permits the design of a small, lightweight, low cost and efficient moderate temperature receiver for use in a dish-Rankine solar thermal system