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By utilizing the similarity characteristics of turbines, their performance can be tested under conditions more relaxed than the design conditions. The use of the similarity model provides the benefit of saving time and the cost required to build a turbine test bench for the performance measurements. This study employs a partial similarity model, rather than a complete similarity model, with a rotational speed of 6000 rpm and air as the working fluid. Condition selection for this model was based on Buckingham's Pi theorem to nondimensionalize the parameters affecting turbine performance. Particularly, the pressure ratio was derived using in-house code. Based on mean-line design results, three-dimensional modeling and numerical analysis were performed using commercial software to compare the performances of the design and partial similarity models. The numerical analysis predicted the isentropic efficiencies of 86.1 % and 80.4 % for the design and partial similarity models, respectively. This study is significant as it enables turbine performance testing at a lower rotational speed with air as the working fluid. [ABSTRACT FROM AUTHOR]

An experimental investigation of R245fa flow boiling in the horizontal flow (θ fd = 0°), vertical upward flow (θ fd = 90°), and vertical downward flow (θ fd = –90°) was carried out using a bare stainless-steel tube (BT) with an inner diameter of 10.02 mm and an effective heating length of 820 mm. The experimental condition was performed under a saturation pressure of 0.6 MPa, a heat flux varying from 4.99–74.60 kW/m2, a mass flux range of 197.94–696.63 kg/(m2·s), and a vapour quality range from 0.01 to 0.9. Five flow patterns, stratified flow, intermittent flow, churn flow, annular flow, and drying flow, could be observed in the experiment. When the heat flux was relatively low (q ≤ 15 kW/m2)), the variation of the heat transfer coefficient with flow direction was relatively gradual. However, when q ≥ 30 kW/m2, a distinct 'U'-shaped trend in the heat transfer coefficient is observed with the flow direction transitioning from vertical downward to horizontal and then to vertical upward. Due to the effect of buoyancy force, the heat transfer performance was relatively better at θ fd = –90° The friction pressure drop in the horizontal flow was the smallest, and the maximum value always occurred at θ fd = 90° Meanwhile, the experimental data for heat transfer coefficient and pressure drop was compared to the well-known correlations from the literature. The predictive correlation by Fang et al. for the heat transfer coefficient was in good agreement with the experimental data. Regarding frictional pressure drop, the Filho, Muller-Steinhagen and Heck and Zakaria correlations were recommended for pressure drop in horizontal flow, upward flow, and downward flow, respectively. [ABSTRACT FROM AUTHOR]

Full-liquid evaporator is an important part of the Organic Rankine Cycle (ORC). It is of great guiding significance to study the pool boiling heat transfer characteristics (high-temperature level) of the evaporator heat exchange tube for evaporator design. The pool boiling heat transfer characteristics (high-temperature level) of working fluid R245fa outside smooth tube and fish-scale tube are analyzed. The outcomes exhibit that the overall Heat Transfer Coefficient (HTC) of the smooth tube is 1.9–3.9 kW m−2 K−1, and the fish-scale tube is 3.8–4.3 kW m−2 K−1 when the saturation temperature of organic working medium R245fa is 80.5 °C. The HTC outside the fish scale tube is 1.45–3.13 instances that of the smooth tube. The external HTC of the smooth tube and fish-scale tube increases with the increase of heat flux, but the strengthening rate decreases. After the outer wall of the heat exchange tube used in the ORC evaporator is strengthened, the water velocity in the tube increases, which can not only strengthen the heat exchange in the tube but also play an anti-scaling effect.

This paper analyzes the developing adiabatic two-phase flow after an expansion valve in an air conditioning system. R245fa and POE 32 mixture is used as the working fluid. The developing two-phase flow patterns are visualized in an 8 mm straight tube after the expansion valve from 15 to 595 mm. To explore the effect of fluid properties on the developing two-phase flow, the experimental results from previous research by the same authors are compared with those of R245fa in this paper. An image analysis technique and a one-dimensional developing two-phase flow model proposed in a previous paper by the same authors (Yao & Hrnjak, 2023c) are applied to both R134a and R245fa. The flow patterns near the expansion valve exhibit some similarities when comparing the two refrigerants. However, a significant contrast emerges in the presence of a greater number of droplets suspended within the vapor phase in the case of R245fa flow. This disparity is primarily attributed to R245fa's higher vapor velocity. Furthermore, R245fa exhibits a shorter developing length than R134a. For fully developed flow, R245fa showcases a more pronounced turbulent behavior, and the transition to annular flow happens at a lower vapor quality in comparison to R134a. All of these distinctions can be adequately accounted for by the proposed model. The developed flow patterns of both refrigerants are compared with some existing flow pattern maps. At last, a new flow pattern map is proposed based on the observed flow patterns in this research. [ABSTRACT FROM AUTHOR]

ORC cycle is one of the most efficient technologies for the utilization of low-grade heat. ORC systems cover a wide range of heat sources and power outputs. Apart from increasing the overall efficiency, CHP systems contribute to the decentralization of energy production, the conservation of primary fuel, the reduction of the emission of greenhouse gasses and the reduction of the cost to the final consumer. This justifies the research activity around CHP-ORC systems. In the present paper, a steady-state thermodynamic model for a 50 kWel biomass microCHP-ORC was developed and four candidate fluids were selected: R124, isobutane, R245fa and isopentane. The multi-objective optimization under supercritical conditions was performed using the genetic algorithm. The thermal efficiency, the exergy efficiency and the total heat exchanger surface were selected as single objectives. The evaporation temperature and pressure and the pinch point temperature differences at the heat exchangers were selected as decision variables. Careful examination of the optimal results revealed a systematic tendency for high evaporation temperatures and pressures and low recuperator pinch point temperature differences. Recuperation was found beneficial in many aspects, especially at higher evaporation temperatures. Also, the use of cogeneration leads to overall system efficiencies that surpass 90%, while simultaneously saving at least 20% fuel. Lastly, isopentane was found to be the best-performing fluid. [ABSTRACT FROM AUTHOR]

In this paper, two power plant configurations for distributed energy, simple and cascaded Organic Rankine Cycle (ORC), were proposed, modeled, analyzed and compared from a technical and economic point of view. It is proposed to use rice husks from a typical mill in Nigeria as fuel for the operation of the power plant, while the working fluids for the studied ORC plants are toluene and R245fa refrigerants. Power plants are modeled on the basis of fundamental technical and economic approaches. At the same time, power generation, as well as energy and exergy efficiency were selected as key technical parameters for the study. The desired economic parameter determines the cost of a unit of energy. It has been established that with proper use of rice husks as a renewable energy source, the energy generated by the ORC power plant can help to meet 27–38 MWh daily needs of the rice factory and its surroundings. The results of the analysis of the energy and exergy efficiency of a simple and cascade ORC power plant as presented indicates a better prospect for the latter. The working/thermal capacities of the plant elements and the loss of exergy in them are analyzed. The directions of increasing the efficiency of the rice husk power plant have been identified, primarily by improving high-temperature heat exchangers. The results of an economic analysis of the viability of the simple and cascade ORC power plants are presented. A simple ORC demonstrates the best economic performance with a unit energy cost of $0.115 per kWh compared to $0.124 per kWh of a cascade ORC. However, a holistic study of technical, economic, social and environmental indicators creates prerequisites for the research and development of a cascade ORC installation. The paper also presents the results of an analysis of the sensitivity of plant performance on the volume of annual production of rice husks, the temperature of the exhaust gases at the outlet of the chimney and the coefficient of the import tariff. A feasibility study of the prospects of the proposed technical solution for poorly electrified countries is presented. [ABSTRACT FROM AUTHOR]

The design of turbines used to convert thermal energy into electrical energy in an organic Rankine cycle (ORC) is crucial. A high-speed turbine requires high-performance bearings, which increases turbine manufacturing costs. In this study, a high-efficiency two-stage axial turbine at a low rotational speed was developed, and the ORC performance was presented. We designed a 180-kW axial turbine of 12,000 rpm. To increase turbine efficiency, the number of turbine stages was set to two, and turbine blades were designed to reduce pressure losses. One-dimensional design parameters of blades that minimized the total pressure loss were selected using an in-house code based on a generalized reduced gradient (GRG) nonlinear algorithm. Three-dimensional turbine blade modeling and numerical analysis were performed using commercial software. The total-to-static isentropic efficiency and output of the two-stage axial turbine were predicted to be 85.1% and 176 kW, respectively. ORC performance was assessed using the predicted turbine performance results. Assuming the temperature of the condenser outlet working fluid to be 25 °C, the ORC thermal efficiency and exergy efficiency were found to be 7.40% and 34.49%, respectively. Our findings highlight the applicability of various rotational speeds and number of stages for an axial turbine in an ORC. [ABSTRACT FROM AUTHOR]

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In this paper, the thermal performance of three low-global warming potential refrigerants R1224yd(Z), R1223zd(E) and R1336mzz(Z) were studied to replace R245fa in the high-temperature heat pump system. The results showed that the heating capacity of R1224yd(Z), R1223zd(E) and R1336mzz(Z) was 6, 12 and 88% less than that of R245fa, respectively. The coefficient of performance (COP) of R1224yd(Z) and R1223zd(E) was 2 and 1% higher than that of R245fa, respectively. However, the COP of R1336mzz(Z) was 5% less than that of R245fa. The difference in compressor discharge temperature between R1224yd(Z), R1223zd (E), R1336mzz(Z) and R245fa was about ±5°C. R1224yd(Z) is the best refrigerant to replace R245fa. R1223zd(E) is the second. R1336mzz(Z) cannot be directly replaced unless the original system is modified. [ABSTRACT FROM AUTHOR]

The design of turbines used to convert thermal energy into electrical energy in an organic Rankine cycle (ORC) is crucial. A high-speed turbine requires high-performance bearings, which increases turbine manufacturing costs. In this study, a high-efficiency two-stage axial turbine at a low rotational speed was developed, and the ORC performance was presented. We designed a 180-kW axial turbine of 12,000 rpm. To increase turbine efficiency, the number of turbine stages was set to two, and turbine blades were designed to reduce pressure losses. One-dimensional design parameters of blades that minimized the total pressure loss were selected using an in-house code based on a generalized reduced gradient (GRG) nonlinear algorithm. Three-dimensional turbine blade modeling and numerical analysis were performed using commercial software. The total-to-static isentropic efficiency and output of the two-stage axial turbine were predicted to be 85.1% and 176 kW, respectively. ORC performance was assessed using the predicted turbine performance results. Assuming the temperature of the condenser outlet working fluid to be 25 °C, the ORC thermal efficiency and exergy efficiency were found to be 7.40% and 34.49%, respectively. Our findings highlight the applicability of various rotational speeds and number of stages for an axial turbine in an ORC.

La complexité de l’écoulement dans un éjecteur nécessite une visualisation très poussée afin de décrire le comportement de l’éjecteur. Cet article repose sur une simulation de l’écoulement de R245fa dans l’éjecteur supersonique gaz-gaz installé dans un système frigorifique réel d’une capacité nominale de 10 TR. Le modèle de turbulence k-e RNG est choisi pour deux modes de fonctionnement de l’éjecteur, critique et sous-critique. L’analyse montre que la contre-pression affect d’une façon significative, à la fois, le débit de réfrigérant induit et le régime de fonctionnement de l’éjecteur. L’utilisation de la base de données de NIST-REFPROP et un maillage adapté pour chacune de simulation permet de donner des résultats très proche à la réalité physique tel que pour le régime critique les erreurs relatives ne dépassent pas 4%, par contre, en régime sous critique, elles sont de l’ordre de 14%.

• A single-phase supersonic ejector working with R245fa is considered. • The experiments indicate three maxima of the entrainment ratio for variable NXP. • RANS model accurately predicts the relation between the entrainment ratio and NXP. • Improved thermodynamic model should include NXP for better prediction performance. • The compound choking criterion explains the displacement of the choking location. Many authors have explored the performance of single-phase ejectors. A significant number of studies have focused on the impact of the nozzle head exit position (NXP) on the ejector performance and reported the existence of a single optimal NXP. However, few others found multiple optimal NXP for the same set of operating conditions. Using an experimental test bench and numerical simulations, the current study observes peaks and valleys in the entrainment ratio (ω) curve when the NXP varies for fixed operating conditions. The Reynolds-Averaged Navier Stokes (RANS) model has successfully captured the complex flow behavior associated with the change in NXP. The Mach contours and compound choking criterion (β) inside the ejector are used to investigate how the NXP affects the entrainment ratio. The results suggest that, the more a flow is double-choked and comprised of a longer compound supersonic section, the more the NXP is deemed optimal. Moreover, the compound supersonic section length is found to vary significantly with the change in NXP. This is the first study to utilize the compound choking theory to explain the impact of the NXP. The compound choking criterion (β) can be used to identify optimal NXP in a commercial system. [ABSTRACT FROM AUTHOR]

• A single-phase supersonic ejector working with R245fa is considered. • Advanced numerical modeling is favorably compared to experimental data. • A movable needle is used to control the throat area in the primary nozzle. • Two needle geometries are tested over a large range of operating conditions. • The maximum transiting exergy efficiency is less than 35% in all conditions. Vapor ejectors raise interest for cooling applications given their low electrical consumption, however, a single ejector suffers from a lack of capacity flexibility. The current study explores the use of an adjustable needle to control the primary nozzle throat area (A t) in view to allow variable ejector capacity. Tests were done using a large scale test bench working with the refrigerant R245fa. CFD simulations using k- ω SST and, for the first time, Scale-Adaptive Simulation (SAS), were also done. A comparison of the simulation results using the two different turbulence models (ω SST and SAS) showed negligible difference. Also, the simulation results with the ω SST model showed good agreement with the experimental values. For fixed operating conditions, the simulation showed that the reduction of the throat area from 1.00 A t to 0.61 A t increased the entrainment ratio from 24% to 56%, but reduced the critical outlet pressure from 440 kPa to 315 kPa. For all conditions, the transiting exergy efficiency η t r , e x first increased with the increase of the outlet pressure (P o u t), reached a maximum value when Pout is close to the critical outlet pressure (P c r i t), and then decreased sharply due to the decrease of the entrainment ratio. Finally, CFD modelings with a blunt tip needle to see the effect of the needle geometry and in order to have a lower throat area value of 0.39 A t. This novel study shows that the ejector equipped with a needle is able to maintain ejector performance with changes in operating conditions. [ABSTRACT FROM AUTHOR]

This paper proposes an integrated numerical–experimental study of a fixed geometry ejector designed for a cooling system activated by waste heat. Ejector operation is analyzed for cases of imposed input and output sets of conditions in terms of pressures and/or temperatures. Experiments with constant primary conditions and secondary temperature were conducted in a range of outlet pressures for model validation purposes. A parametric analysis was then performed for constant pressure and temperature conditions at both inputs (primary and secondary) by varying the outlet pressure. For each test case, performance in terms of entrainment ratio, local parameters distributions (P, M, τ) and the internal flow structure were analyzed in an attempt to establish a link between the external constraints, the flow structure, the operation stability and performance within the range of cooling applications. The ranges of operating conditions investigated were Pp = 4.77 bar, Tp = 83 °C and, respectively, 1.7 ≤ Pc ≤ 2.4 bar, 12.5 °C ≤ Te ≤ 16.5 °C, at saturation. Experimental entrainment ratio, ERexp in the range of 0.12–0.22 was numerically simulated within ± 10%. It was shown that both the ejector operation and the internal flow configurations were sensitive to backpressure. More particularly, an optimal backpressure exists to which corresponds an on-design conditions with maximized entrainment ratio and a shock-wave train located at the end of the mixing chamber. A backpressure increase sets the ejector in off design. This mode of operation is characterized by a shift of the shock train toward the inlets, a disturbance of the flow configuration, a diminution of the entrainment ratio and a deterioration of the operation stability. On the other hand, a backpressure decrease does not affect the ejector stability of operation at its maximum entrainment ratio for the prevailing conditions. [ABSTRACT FROM AUTHOR]

Single-stage regenerative organic Rankine cycle (SSRORC) is a system that is used for increasing the simple organic Rankine cycle (ORC) performance. Open feed organic heater (OFOH) addition in the ORC system increase power and efficiency of the system. This paper analyzes the SSRORC performance with a variation of P6/P1 ranges from 1.25 to 3.75 with an increment of 0.25, where P6 is the OFOH pressure at the inlet side and P1 is the pressure at the inlet pump 1, respectively. Hot water was used as the heat source with 100 °C and 100 l/min of temperature and volume flow rate as the initial data. R227ea, R245fa, and R141b were chosen as working fluids for performance analysis. The analysis was performed by calculating the heat input, heat loss, pump and turbine power, net power, and thermal efficiency through energy balance. Exergy input, exergy output, and exergy efficiency were analyzed through exergy balance. The results show that P6/P1 = 2 obtains the highest performance than the other pressure ratios for R227ea, while R245fa and R141b obtain the highest performance at P6/P1 = 2.25. R141b has better performance than the other two fluids with 10.97 % and 11.96 % for thermal and exergy efficiency. The results show that the ratio of OFOH pressure at the inlet side to the pressure at inlet pump 1 (P6/P1) in the middle value obtains the best performance.

Organic Rankine Cycle (ORC) fluids are applied in Shell and Tube Heat Exchanger for waste heat recovery to increase its efficiency. Various methods have been applied in the ORC in shell and tube heat exchanger, which has the limitation of low efficiency in optimization. In this research, Enhanced Teacher Learning Based Optimization (ETLBO) method has been proposed to increase the efficiency of the ORC in shell and tube heat exchanger. The Michalewicz was applied to the optimization method to provide global optimum and escape from the local optima. The E-TLBO method improves the convergence of the optimization and provides the effective performance in finding solution. The E-TLBO method has the advantages of two parameters such as population size and the number of iterations requires to set the value for optimization. The Shell and tube heat exchanger model has been developed to evaluate the performance of the optimization. The performance of E-TLBO is evaluated in four fluids namely R245fa, R134a, R290, and R600a in ORC analysis. The proposed E-TLBO method is compared with existing methods of Bell- Delaware and Kinetic Gas Molecule Optimization (KGMO) method. This analysis showed that R245fa fluid has a higher mass flow rate compared to other fluids. The proposed E-TLBO method has an enhancement factor of 3.14 and the existing KGMO has a 1.88 enhancement factor in R245fa fluid. [ABSTRACT FROM AUTHOR]

Abstract The binary-flashing cycle (BFC) is supposed to be a promising technology for geothermal recovery due to the full use of geofluid. For further performance improvement, the potential of using mixtures of a hydrocarbon and a retardant in the BFC system is investigated. R245fa is selected as a retardant and blended with R600 to form zeotropic mixtures. With the thermal efficiency (η th), exergy efficiency (η ex), net power output per ton geofluid (PRW), and exergy destruction rate (E d) as evaluation indexes, the flowsheet modeling and optimization are conducted to explore the optimal compositions and operating parameters. It is revealed the optimal mass fraction of R600/R245fa is 0.44/0.56, at which the flammability of R600 is suppressed, the global warming potential (GWP) of R245fa is reduced. The maximum η ex and PRW are higher than those of component fluids. The maximum E d occurs in the heat exchanger, which should be optimized. The recommended generation pressures are 1200–1430, 1240–1480, 1220–1460, and 1170–1420 kPa, respectively, for R600 mass fraction of 0.2, 0.4, 0.6, and 0.8. In addition, the flashing temperature is also optimized. Although the mixtures do not always yield superior performance, it is still beneficial to apply the mixtures to the BFC system through systematic consideration of safety and environmental friendliness.

The aim of this study is to analyse from the thermodynamic, environmental and economic point of view an ORC for heat recovery from urban waste, using R245fa as a working fluid on the example of Terceira Island (Azores). The proposed ORC system includes two evaporators, two turbines, a condenser, a pump and a generator. The thermodynamic model is created using the Visual Basic programming language. In order to analyse the influence of pressure, temperature and mass flow on net output, efficiency, and mass flow rate of the power plant, the sensibility analysis is carried out. The results show that from the energetic point of view, urban waste recovery (using an ORC) could be a viable solution on Terceira Island, since the maximum net output produced from this system for a mass rate of 19 727 tonnes is 485 kW. The efficiency of the ORC is 25 %. Environmentally, the incineration of the urban waste produced on the island is a positive solution for these residues since it will reduce the amount of waste deposited in the landfill. However, this project is not economically viable. The losses estimated in this study exceed 500 000 EUR (per year).

• Real gas equations of state compared with REFPROP for use in CFD analysis of twin screw expanders. • Redlich–Kwong, Soave-RK, Aungier-RK, Peng–Robinson equations assessed in ANSYS CFX. • R245fa and low GWP alternatives R290, R1336mzz(Z) and R1233zd(E) were evaluated. • Expander performance deviated within limits of 0.5–2.2% with real gas models. • For the same level of convergence of the solver, about 43% computation time saved. Positive displacement expanders are widely investigated and theirs models commonly use the REFPROP database to evaluate fluid properties. However, estimating procedures in CFD models using REFPROP result in heavy use of CPU time. Therefore, a study has been carried out to determine if simpler methods for fluid property estimation are suitable. The ANSYS CFX solver used includes a number of cubic equations of state, namely, the Redlich Kwong, Soave Redlich Kwong, Aungier Redlich Kwong and Peng Robinson. To determine their suitability, performance simulations were carried out with each of them, on a twin screw expander with a 4/5 rotor configuration and an "N" rotor profile, operating with R245fa, R290, R1336mzz(Z) and R1233zd(E). For each considered equation, the expander's performance results deviation from those obtained using REFPROP is evaluated. These results show that the ideal gas equation of state gives predictions of flow and power that deviate significantly from those determined with REFPROP. The alternatively available cubic equations give far better agreement. Of these, the RK equation has the highest deviation, although it differs by only 2.2% maximum from the REFPROP values. The PR equation yields the closest agreement with a deviation of the order of only 0.8%, while the deviation with both SRK and ARK equations is less than 1.1% maximum, practically negligible. Apart from the good agreement obtained, the use of the real gas equations, in place of REFPROP, resulted in a saving of approximately 43% in CPU operating time to obtain same level of convergence of the solver. [ABSTRACT FROM AUTHOR]

Pulsating heat pipes (PHP) are increasingly attracting attention for their potential to downsize electronic devices to be designed. Unlike conventional heat pipes, PHP maintains high heat transfer performance despite having a smaller diameter, and have a smaller dependence on heating orientation. In this study, hydrofluoroolefins (HFO) are selected as an environmentally-friendly and non-flammable working fluid for PHP. The flat-plate PHP is made of aluminum alloy, and its dimensions are a length of 222 mm, a width of 55 mm, and a thickness of 3 mm. It is prepared the channel, which is 1.2 mm × 1.2 mm square, 22 turns, and closed-end serpentine. The working fluids are R1233zd(E) and R1336mzz(Z) as HFO, and the other is R245fa as one of conventional hydrofluorocarbon (HFC). The filling ratio of each working fluid is approximately 50 %. The flat-plate PHP is set vertically, heated in the top heating orientation, and measured the equivalent thermal conductivity. When the cooling temperature is 40 °C, the equivalent thermal conductivity with R1233zd(E) and R1336mzz(Z) are between 2500 and 4000 W/(m･K), and higher than that of R245fa. When the cooling temperature is −5 °C and the heat transport rate is less than 100 W, the equivalent thermal conductivity with all working fluids are equivalent, and R1233zd(E) and R1336mzz(Z) have larger temperature dependence than R245fa. The maximum heat transport rate with R1233zd(E) is the highest, and around 190 W. When the cooling temperature is 40 °C, the maximum heat transport rate with R1336mzz(Z) is 150W, and higher than that with R245fa (104W). From the above results, we have concluded that PHP with R1233zd(E) and R1336mzz(Z) have higher heat transport performance than that with R245fa, and R1233zd(E) and R1336mzz(Z) may replace as the working fluid for PHP, instead of conventional R245fa.

A 195 cm3 swash-plate piston expander was tested in an ORC using R245fa as working fluid. Rotational speeds ranging from 1,000 to 4,000 RPM and pressure ratios from 7 to 12 were imposed. In total, 65 steady state points were measured. With these measurements, performance maps were generated to point out the influence of rotational speed and levels of pressure on mechanical power and isentropic efficiency. These maps have highlighted the existence of an optimal rotational speed of around 3,000 RPM maximizing the mechanical power, while the speed that maximizes the isentropic efficiency lies between 2,000 and 2,500 RPM. The maximal mechanical power and isentropic efficiency were 2.8 kW and 53%, respectively. Then the measurements were used to analyze the losses. This analysis has shown that, under the expansion and compression limit, the theoretical isentropic efficiency has values comprised between 90 and 70% for pressure ratios of 7–12. The filling factor affects the isentropic efficiency for low rotational speeds and low pressure ratios. Indeed, indicated isentropic efficiency is around 60% for 1,000 RPM and around 75% for 4000 RPM. These values stay quite constant with the pressure ratio. Finally, a mechanical efficiency comprised between 40 and 90% was observed, which lowers the isentropic efficiency to values comprised between 30 and 53%. Finally, a model based on energy and mass conservation inside a cylinder volume was successfully calibrated and was able to predict mass flow rate, mechanical power, and exhaust temperature with good agreement. This model has enabled disaggregation of the influence of pressure drops and leakages on the filling factor, then on the isentropic efficiency. This analysis has shown that pressure drops mainly affect the compactness of the expander, and not so much the isentropic efficiency (except for low rotational speeds where pressure drops can lower the isentropic efficiency by 14%). In contrary, leakages have a strong impact. The importance of the different sources of losses varies with the speed. For the optimal speed of 2,500 RPM, under-expansion and compression have the strongest impact, followed by mechanical losses, leakages and pressure drops, respectively.

The organic Rankine cycle (ORC) is a thermodynamic cycle in which electrical power is generated using an organic refrigerant as a working fluid at low temperatures with low-grade enthalpy. We propose a turbine embedded in a generator (TEG), wherein the turbine rotor is embedded inside the generator rotor, thus simplifying turbine generator structure using only one bearing. The absence of tip clearance between the turbine rotor blade and casing wall in the TEG eliminates tip clearance loss, enhancing turbine efficiency. A single-stage axial-flow turbine was designed using mean-line analysis based on physical properties, and we conducted a parametric study of turbine performance, and predicted turbine efficiency and power using the tip clearance loss coefficient. When the tip clearance loss coefficient was applied, turbine isentropic efficiency and power were 0.89 and 20.42 kW, respectively, and ORC thermal efficiency was 4.81%. Conversely, the isentropic efficiency and power of the turbine without the tip clearance loss coefficient were 0.94 and 22.03 kW, respectively, and the thermal efficiency of the ORC was 5.08%. Therefore, applying the proposed TEG to the ORC system simplifies the turbine generator, while improving ORC thermal efficiency. A 3D turbine generator assembly with proposed TEG structure was also proposed.

Evaporators used in organic Rankine cycles (ORC) are designed using existing flow boiling correlations that are mainly based on HVAC&R data. However, the ORC evaporators employed in the industry typically have larger diameters and operational conditions at higher reduced pressures compared to the HVAC&R applications. The present study presents the results of flow boiling heat transfer experiments in operational conditions that are representative for an industrial waste heat recovery low-temperature ORC’s evaporator tube, by being performed at high reduced pressures and in a large-diameter horizontal tube with R245fa as working fluid. The measurements are performed within a range of mass flux, saturation temperature and heat flux at 83–283 kg/m2s, 85–120 °C (8.9–19.2 bar) and 17–29 kW/m2, respectively. Test section is a round and plain horizontal carbon steel tube with 21 mm I.D., 2.5 m length. 513 local two-phase heat transfer coefficients are recorded. The experimental results are compared with each other to reveal heat transfer coefficient trends with respect to varying experimental conditions. Four distinctive heat transfer zones are observed, namely, the nucleate boiling dominant (NBD) zone, weakening nucleate boiling dominance (WNBD) zone, flow boiling zone (FBZ) and the dry-out zone (DOZ). Heat transfer coefficient vs vapor quality trends partly resembled CO2 flow boiling results reported in the literature. Two flow boiling correlations moderately predicted the data.

High temperature heat pumps (HTHPs) with the output temperature above 100°C attract more and more attention in industrial heat recovery. It can effectively elevate the grade of thermal energy and recover waste heat to reduce the consumption of primary energy. In order to compare the performance of different HTHPs, six refrigerants were selected and simulated in an idealized refrigeration cycle including natural refrigerant (R718), HCs (R600, R601), HFOs (R1234ze(Z), R1336mzz(Z)) and HFC (R245fa). The simulation results showed that R718 has the best system performance and Carnot efficiency (COP/COP Carnot) among all those refrigerants. Then an R718 HTHP prototype was built to verify the feasibility of R718 high temperature output in industrial processing. The experimental comparison of R718 and R1336mzz(Z)/R600/R245fa showed that no matter compared with the novel HFO refrigerant R1336mzz(Z), the flammable HC R600 or the traditional HTHP refrigerant R245fa, R718 has its unique advantages in HTHP applications. When applied in industrial heat recovery, R718 HTHP not only can satisfy the demand for high output temperature but also has better performance. • A property comparison of several Low-GWP refrigerants was made. • The system performance of selected refrigerants was simulated and compared. • The trend of COP of R718 HTHP is totally different from other refrigerants. • The R718 HTHP shows the best system performance at high temperature output. [ABSTRACT FROM AUTHOR]

This work presents a combined experimental and thermodynamic approach used to investigate the influence of droplet injection on the performance of an ejector-based refrigeration cycle developed for Heating, Ventilation and Air-Conditioning (HVAC) applications. Thermodynamic models have been developed within MATLAB for each component of the cycle. They are validated against experimental data of an R245fa test rig installed at Hydro-Québec's Energy Technologies Laboratory (LTE). The numerical models agree fairly well with the experiments. The results show that injecting R245fa droplets at the end of the ejector diffuser with different glycol temperatures ranging from 20 to 26 °C has a significant impact on the performance of the ejector itself and more interestingly on the performance of the whole cycle. It reduces especially and significantly the temperature and the pressure of the overheated vapors at the outlet of the ejector leading to a significant improvement of the thermodynamic coefficient of performance (COP) by up to 20%. [ABSTRACT FROM AUTHOR]

In binary geothermal power plants based on the Organic Rankine Cycle (ORC) typically shell-and-tube heat exchangers are used as evaporators. In the shell-side, nucleate boiling of the working fluid takes place on the external surfaces of tubes. For the replacement of fluids with high global warming potential (GWP) or selection of efficient working fluids, a comprehensive evaluation has to be performed. Therefore, the knowledge about the nucleate pool boiling heat transfer coefficient (HTC) in combination with the electrical power output is necessary. In this study, the focus is led on the experimental evaluation of nucleate pool boiling heat transfer correlations for R245fa and its possible replacement R1233zd(E) in ORC applications. The nucleate boiling HTC on a horizontal tube and the electrical power generation of a 1 kW scroll expander are simultaneously measured with an ORC test rig for both fluids. The thermal input is provided by an electrically heated preheater and evaporator. Nucleate boiling takes place on a plain copper tube with an outer diameter of 32 mm and a heated length of 822 mm. The surface temperature of the copper tube is determined by thermocouples within the tube in consideration of thermal conduction. The obtained measurement results, regarding heat transfer characteristics as well as power output, show that the working fluid R245fa performs better at equal saturation temperatures due to the higher density and saturation pressure, and the lower viscosity. The HTC for R245fa is up to 43.2% higher in comparison to R1233zd(E). The experimental HTC are compared to selected nucleate pool boiling HTC correlations. The evaluation reveals that correlations according to Cooper and Gorenflo et al. show the slightest mean absolute deviations between 4.75% and 15.65% for both working fluids. • An evaluation of HTC correlations is presented to assess their prediction accuracy. • Nucleate pool boiling HTC and power of scroll expander are simultaneously measured. • R245fa performs better than R1233zd(E) at equal saturation temperatures. • Cooper and Gorenflo correlations show the slightest deviations. [ABSTRACT FROM AUTHOR]

This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a direct method of calculating the optimal ejector performance (entrainment ratio or ER) without the need for iterative methods, which have been conventionally used. The values of three ejector efficiencies used to account for losses in the ejector are calculated by using a systematic approach (by employing CFD analysis) rather than the hit and trial method. Both experimental and analytical data from literature are used to validate the presented analytical model with good agreement for on-design performance. R245fa working fluid has been used for low-grade heat applications, and Engineering Equation Solver (EES) has been employed for simulating the proposed model. The presented model is suitable for integration with any thermal system model and its optimization because of its direct, non-iterative methodology. This model is a non-dimensional model and therefore requires no geometrical dimensions to be able to calculate ejector performance. The model has been validated against various experimental results, and the model is employed to generate the ejector performance curves for R245fa working fluid. In addition, system simulation results of the ejector refrigeration system (ERS) and combined cooling and power (CCP) system have been produced by using the proposed analytical model.

R245fa and R600 are two working fluids with which organic flash cycle (OFC) yields acceptable thermodynamic and economic performance to recover waste heat from low-temperature flue gas free from SO2. However, very high flammability of R600 and higher global warming potential (GWP) of R245fa are two issues of serious concern. Mixture with suitable mole fraction of these two fluids as the optimum working fluid for OFC is explored in this study. A mixture of R245fa and R600 with a mole fraction ratio (0.6/0.4) is selected conservatively as the working fluid of the OFC to suppress the flammability of R600. The corresponding value of GWP of the mixture comes below 800 kg of CO2 per kg of working fluid. It is observed that OFC using this mixture may yield higher work output per kg of flue gas flow and lower bare module cost/kW compared to that of OFC using either of the pure working fluid. OFC yields the highest work output per kg of flue gas for an R245fa/R600 mixture with (0.4/0.6) mole fraction ratio. Bare module cost per unit power output becomes a minimum when R245fa mole fraction is 0.37 in the mixture. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• R1233zd(E) and R245fa were tested during flow boiling inside a mini microfin tube. • Heat transfer coefficient and pressure drop were experimentally measured and discussed. • Several literature models were assessed against experimental data. • The performance of R1233zd(E) and R245fa was compared. R1233zd(E) has been proposed as low GWP alternative to R245fa. This paper compares the R1233zd(E) and R245fa performance during flow boiling inside a small diameter microfin tube having internal diameter at the fin tip equal to 4.2 mm, 40 fins, 0.15 mm high, and a helix angle of 18°. The experimental measurements were carried out at a constant mean saturation temperature of 30 °C, by varying the refrigerant mass velocity between 100 kg m−2 s−1 and 300 kg m−2 s−1, the mean vapor quality from 0.1 to 0.95, and the heat flux from 15 to 90 kW m−2. The experimental results showed that R1233zd(E) presented almost similar flow boiling heat transfer coefficients at all the investigated mass velocities but slightly higher two-phase frictional pressure drops. The experimental measurements were compared against the calculated values of boiling heat transfer coefficients and frictional pressure drops from several models selected from the open literature. [ABSTRACT FROM AUTHOR]

The selection of appropriate fluid in Organic Rankine Cycles (ORC) is an important issue. The thermodynamic properties of working fluids affect the efficiency, operation and environmental impact of the system. Many working fluids for ORC power plants are available. Pentane (R-601) and R245fa are the most used for ORC. In this work, a gene expression programming (GEP) model for estimating thermodynamic properties of pentane (R-601) and R245fa was used. New formulations are presented for determination of the enthalpy and entropy values of two working fluids. The actual results were compared to the results obtained with GEP. The obtained results showed that the formulations are effectively capable of evaluating the thermodynamic properties of working fluids. The GEP-based formulations are simple. These formulations will be helpful for thermodynamic analysis of ORC systems. [ABSTRACT FROM AUTHOR]

• Falling film evaporation of refrigerants on horizontal smooth tube was investigated. • Flow patterns of falling liquid film in adiabatic and heating conditions were observed. • Effects of flow rate, heat flux, temperature, and refrigerant properties were clarified. • New prediction method of heat transfer was developed for falling film evaporation. Falling film evaporation on a horizontal smooth tube with outer diameter of 19 mm was investigated using two refrigerants, R1234ze(E) and R245fa. The heat transfer coefficients were obtained at a film Reynolds number range of 100–1000, heat flux range of 2.5–40 kWm−2, and saturation temperature range of 10–20 °C. The flow patterns of falling liquid film between tubes were observed under adiabatic and heating conditions. The effects of film Reynolds number, heat flux, saturation temperature, and refrigerant properties on the heat transfer were clarified. The heat transfer of falling film was characterized by nucleate boiling and convective heat transfer. Heat transfer was enhanced by increasing heat flux at high heat flux conditions, while heat flux at low heat flux condition had no significant influence. The measured heat transfer coefficients were compared with previous correlations, and a new prediction model that considers both nucleate boiling and convective heat transfer was developed for falling film evaporation. [ABSTRACT FROM AUTHOR]

Abstract This paper presents performance analysis of a high temperature cascade organic Rankine cycle coupled with water heating system capable of providing maximum power output of 542 kW and hot water at 35 °C for household purposes. The analysis makes use of monthly ambient air and water temperature data of the city of Busan, South Korea as input parameters of the system. The working fluid at the exit of turbine 1 is split into two mass fractions, one providing heat to the bottom cycle (ORC II) and the other used to heat water in the water heating system. These mass fractions are adjusted according to the expected seasonal demand of hot water. Among three high critical temperature working fluids, m-xylene has been selected for the top cycle whereas R245fa has been selected for the bottom cycle among five low critical temperature working fluids. A comprehensive thermal and exergy efficiency analysis shows the performance of the system during the different months of the year. The analysis show the comparison of the winter season (when demand for hot water is high) with the summer season (when demand for hot water is low). Highlights • High temperature cascade ORC coupled with water heating system is investigated. • Ambient air and water temperature data are used as input parameters of the system. • The water heating system shows greatest variation in exergy destruction values. • m-xylene and R245fa are selected as best fluids for top and bottom ORCs. • Winter months show greater η t h and summer months show greater η e x . [ABSTRACT FROM AUTHOR]

Featured Application: The results introduced in this work can offer a good suggestion for the construction of actual organic Rankine cycle system from an economic point of view. The organic Rankine cycle (ORC) is a popular technology used in waste heat recovery and low-grade heat utilization, which are two important measures to solve the problems brought by the energy crisis. The economic performance of ORC system is an important factor affecting its application and development. Therefore, the economic analysis of ORC is of great significance. In this study, R123 and R245fa, two frequently-used working fluids during the transition period, were selected for calculating and analyzing the economic performance of an ORC used for recovery of waste heat with a low flow rate and medium-low temperature. Five traditional economic indicators, namely total cost, net earnings, payback period, return on investment, levelized energy cost, and present value of total profit in system service life, which is a relatively new indicator, were used to establish the economic analysis model of ORC. The variation effects of evaporation temperature, condensation temperature of working fluid, flue gas inlet temperature, and mass flow rate of flue gas on the above six economic indicators were analyzed. The results show that the optimal evaporation temperature of R123 is 125 °C, the optimal condensation temperature is 33 °C, and the optimal heat source temperature is 217 °C. For R245fa, the optimal evaporation temperature is 122 °C, the optimal condensation temperature is 27 °C, and the optimal heat source temperature is 177 °C. The economic performance of an ORC demonstration project was reported and used for comparison with the estimation and analysis. It was found that the single screw expander has an excellent economy performance, which greatly reduces the proportion of expander cost in the ORC system. [ABSTRACT FROM AUTHOR]

Highlights • Supercritical heat transfer characteristics of R1233zd(E) was investigated. • Effects of mass flux, heat flux, and pressure were discussed. • Better heat transfer characteristics was obtained compared with that of R245fa. • No abrupt heat transfer deterioration took place during the experiment. Abstract The recently developed low-global-warming-potential working fluid R1233zd(E) is regarded as an alternative to R245fa in the organic Rankine cycle (ORC) considering the environmental impacts. In this study, the heat transfer characteristics of R1233zd(E) at supercritical pressures were investigated experimentally in a vertically upward flow inside a tube. The inner diameter and length of the test tube were 4 mm and 1.04 m, respectively. With the known supercritical heat transfer characteristics of R245fa, the experiment was conducted under the mass fluxes of 400 and 600 kg/m2 s, heat flux from 20 to 80 kW/m2, and pressure of 3.93 and 4.40 MPa, which were equal to the reduced pressure (P / P cri) of 1.10 and 1.23, respectively. The effects of mass flux, heat flux, and pressure are discussed based on the experimental data. The experimental results are compared with existing correlations and the correlation proposed by Petukhov et al. shows the best predictability. Moreover, a comparison with the heat transfer coefficients of R245fa is presented. For the new R1233zd(E) working fluid, the abrupt deterioration characteristics did not occur under the experimental conditions, and a higher heat transfer coefficient was obtained in the supercritical region, in comparison to that obtained with R245fa. [ABSTRACT FROM AUTHOR]

Highlights • The performance of an oil-free scroll expander is presented. • A total of 75 steady-state points with R245fa have been collected. • The friction losses were quantified to be up to 20% of total power output. • Semi-empirical and Artificial Neural Network models have been compared in a systematic way. • Experimental data and simulation model source-codes have been provided. Abstract Organic Rankine cycles (ORCs) are thermodynamic power cycles designed to generate work from a wide range of heat source conditions. In particular, low-grade waste heat recovery (WHR) (<150 ° C) can be effectively exploited with such systems. The efficiency of an ORC is highly dependent on its expander performance. In the low power output range (<10 kW), scroll expanders are cost-effective. Although a number of researchers have investigated the use of scroll compressors as expanders, very little work has been carried out in modeling and investigating the performance of oil-free expanders. In this work, an experimental evaluation of a newly designed open-drive oil-free scroll expander was performed. The expander had a nominal capacity of 5 kW, built-in volume ratio of 3.5, and was integrated into an ORC test-rig with R245fa as working fluid. The experimental data consisted of 75 data points that were used to map the oil-free operation of the scroll expander over five expander rotational speeds (from 800 rpm to 3000 rpm). Two heat sources inlet temperature, i.e. 85 ° C and 110 ° C, were investigated. The scroll expander achieved a maximum overall isentropic efficiency of 0.58 for the temperature source of 110 ° C, for the imposed specific volume ratio of 6.12 at rotational speed of 1600 rpm. For the same heat source, the maximum expander power output was 3.75 kW for an imposed specific volume ratio of 6.55 and rotational speed of 2500 rpm. Besides the experimental work, the performance of the expander was characterized by means of a semi-empirical model to break-down the different loss terms. A well known model available in the literature was extended to account for the major frictional losses in a scroll machine, i.e. bearings, tip-seals and other sources of friction. Additionally, an Artificial Neural Network (ANN) modeling approach was also proposed to achieve higher accuracy in mapping expander performance for use in system simulation. The experimental data and model source codes are provided as supplementary materials. [ABSTRACT FROM AUTHOR]

The R245fa condensation heat transfer is investigated in a phase separation shell-tube condenser with mesh tubes inserted. The condenser has three copper tubes which have an inner diameter of 14.70 mm and a heat transfer length of 1600 mm. Four mesh tubes with mesh pore width of 15 μm are arranged in each copper tube. The comparative experiments are conducted for condensers with or without mesh tubes inserted. The flow pattern visualization is investigated to explore heat transfer enhancement mechanisms. The results showed that, with vapor mass qualities and mass fluxes increased, condensation heat transfer coefficients and friction pressure drops are increased, but heat transfer enhancement ratios and performance evaluation parameters are decreased. At low mass fluxes, the heat transfer coefficients behave a slow decrease trend with increase of inclination angles. The pressure difference between annular region and core region drives liquid flow towards core region, reducing liquid film thickness on tube bottom and increasing vapor void fractions near tube wall. With increase of inclination angles, the pressure difference is reduced but liquid film thickness on tube bottom is increased. For horizontal flow, there is an optimal match between pressure difference of annular region and core region and liquid-mesh tube contact area. Under such circumstance, the heat transfer enhancement ratios reach maximum. [ABSTRACT FROM AUTHOR]

Abstract Post-combustion capture plants are widely studied because they represent a feasible solution to limit the CO 2 emissions from existing plant. They can be applied to power plants and to industrial plants. The captured CO 2 is transported to dedicated sites to be sequestrated. In this study, the captured CO 2 from a coal-fired power plant is exploited to extract the geothermal energy for subsequent electric production. The system of wells consists of one of injection in a geothermal source of about 200-300 °C and one of production from which the CO 2 exits at high pressure and high temperature. It is expanded in a turbine to extract part of the energy and it is cooled to be sent to the storage site. The cooling process exchanges heat with an Organic Rankine Cycle to convert the heat to electric power. The ORC plants are tested with five different substances: R245fa, HCFO, hexane, pentane, and Isobutane. The better performances are obtained with the latter two. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper experimentally investigates the thermal hydraulic characteristics for three types of fluid on plate heat exchanger surfaces. The three types of fluid are R245fa, glycol and water. The characteristics of heat transfer coefficient Nu and friction factor f are given. The concept of pump power is provided to overall evaluate the enhanced heat transfer. The dimensionless correlation equations of Nu and f factors are provided usingmultiple regression method. The mean absolute errors for the Nu and f factor are 9.7 and 6.8% in the whole test range. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • The pyrolysis mechanism of R601a/R245fa is first investigated. • R245fa has a certain inhibitory effect on the initial pyrolysis of R601a. • R245fa inhibits the generation of methane products from R601a decomposition. • The thermal stability follows the following order: pure R601a < R601a/R245fa < pure R245fa. R601a/R245fa mixture is one kind of promising working fluid in ORC. In this study, the thermal decomposition mechanism of R601a/R245fa mixture was studied by reactive molecular dynamic simulation (ReaxFF-MD) and density function theory (DFT). In the R601a/R245fa mixed working fluid system, pyrolysis begins with the C C bond breaking of R601a, generating a large number of CH 3 radicals, which further decompose to produce a certain amount of H radicals. Due to the presence of R245fa, the hydrogen extraction reactions between CH 3 , H radicals and R601a, which have low energy barriers were inhabited to a certain extent. The addition of R245fa reduces the generation of small molecule flammable gases such as H 2 and CH 4 , however, it increases the risk of HF generation. When the molar ratio of R245fa exceeds 0.5, pyrolysis will cause more serious HF corrosion problems than pure R245fa. [ABSTRACT FROM AUTHOR]

The paper presents an extensive investigation of a small-scale sliding vane rotary expander operating with R245fa. The key novelty is in an innovative operating layout, which considers a secondary inlet downstream of the conventional inlet port. The additional intake supercharges the expander by increasing the mass of the working fluid in the working chamber during the expansion process; this makes it possible to harvest a greater power output within the same machine. The concept of supercharging is assessed in this paper through numerical computational fluid dynamics (CFD) simulations which are validated against experimental data, including the mass flow rate and indicated pressure measurements. When operating at 1516 rpm and between pressures of 5.4 bar at the inlet and 3.2 bar at the outlet, the supercharged expander provided a power output of 325 W. The specific power output was equal to 3.25 kW/(kg/s) with a mechanical efficiency of 63.1%. The comparison between internal pressure traces obtained by simulation and experimentally is very good. However, the numerical model is not able to account fully for the overfilling of the machine. A comparison between a standard and a supercharged configuration obtained by CFD simulation shows that the specific indicated power increases from 3.41 kW/(kg/s) to 8.30 kW/(kg/s). This large power difference is the result of preventing overexpansion by supercharging. Hence, despite the greater pumping power required for the increased flow through the secondary inlet, a supercharged expander would be the preferred option for applications where the weight of the components is the key issue, for example, in transport applications.

The organic Rankine cycle (ORC) is a popular technology used in waste heat recovery and low-grade heat utilization, which are two important measures to solve the problems brought by the energy crisis. The economic performance of ORC system is an important factor affecting its application and development. Therefore, the economic analysis of ORC is of great significance. In this study, R123 and R245fa, two frequently-used working fluids during the transition period, were selected for calculating and analyzing the economic performance of an ORC used for recovery of waste heat with a low flow rate and medium-low temperature. Five traditional economic indicators, namely total cost, net earnings, payback period, return on investment, levelized energy cost, and present value of total profit in system service life, which is a relatively new indicator, were used to establish the economic analysis model of ORC. The variation effects of evaporation temperature, condensation temperature of working fluid, flue gas inlet temperature, and mass flow rate of flue gas on the above six economic indicators were analyzed. The results show that the optimal evaporation temperature of R123 is 125 °C, the optimal condensation temperature is 33 °C, and the optimal heat source temperature is 217 °C. For R245fa, the optimal evaporation temperature is 122 °C, the optimal condensation temperature is 27 °C, and the optimal heat source temperature is 177 °C. The economic performance of an ORC demonstration project was reported and used for comparison with the estimation and analysis. It was found that the single screw expander has an excellent economy performance, which greatly reduces the proportion of expander cost in the ORC system.

Improving ship system efficiency is a growing concern for the marine industry. New regulations imposed by the International Maritime Organization (IMO) have set efficiency targets for new and existing ships. These targets are outlined in the energy efficiency design index (EEDI) and will reach a maximum of 30% by 2025. In order to satisfy the regulations, ship owners are exploring new methods to improve the efficiency of existing systems. One such method is to capture and repurpose engine waste heat. Many ships employ exhaust steam boilers to recover heat from engine exhaust. This represents a source of high quality heat (≥ 200°C). At these temperatures, it is relatively easy to extract thermal energy. In contrast, low quality heat sources, such as engine jacket water (≤ 100°C), have been largely ignored. Steam production is impractical at such low temperatures. A new technology was needed to take advantage of low temperature heat sources on the ship. Calnetix Technologies, in conjunction with Mitsubishi Heavy Industries (MHI), developed an Organic Rankine Cycle (ORC) specifically designed to utilize engine jacket water as a heat source. The first prototype was successfully built, tested, and certified by Lloyd’s Registry (LR) and Nippon Kaiji Kyokai (NK) in March 2015. The system generates up to 125 kW from a heat source with temperature range 80°C to 95°C. This prototype was installed, commissioned, and placed into service on the Arnold Maersk container ship in April 2016. This paper will discuss difficulties which arose during the installation. It will also present and discuss data collected by the ORC’s sensors during its first several months of operation. Finally benefits of the ORC operation in conjunction with auxiliary ship systems will be explained. [ABSTRACT FROM AUTHOR]