Net Power Generation Research Articles

Modelling of sorption-enhanced steam methane reforming in a fixed bed reactor network integrated with fuel cell

In this study sorption-enhanced steam methane reforming (SE-SMR) in fixed beds is investigated by means of 1D numerical modelling, and the model is validated with the data reported in the literature. Isothermal conditions (973 K) are considered, and the equilibrium between the carbonation and calcination stages is shifted by a pressure swing: 3.5 · 106 Pa and 1013 Pa, respectively. The results showed that under these operating conditions at least 8 reactors in parallel are required to continuously produce a high-purity stream of H2, and a separated stream of concentrated CO2. The average H2 purity is 0.92, whilst the average H2 yield and selectivity are 2.9 molH2 molCH4−1 and 90%, respectively. A thermodynamic analysis was performed, which highlighted that, by using a portion of the produced H2 (about 0.4 molH2 molCH4−1), it is possible to fully cover heat and power demands of the process, making it completely energy self-sufficient. In the case when the proposed SE-SMR is integrated with a solid oxide fuel cell, net power generation at the scale of ∼950 kWel can be achieved with a net efficiency of the entire system of 51%, with the important feature that CO2 is concentrated.

Enhanced Performance Dual Stage Pressure Retarded Osmosis

A dual stage PRO process has been proposed for power generation from a salinity gradient across a semi-permeable membrane. Both closed-loop and open-loop dual stage PRO system were evaluated using 2 M NaCl and Dead Sea as draw solutions, whereas the feed solution was either fresh water or seawater. The impact of feed salinity gradient resource and feed pressure on the net power generation and water flux were evaluated.DSPRO can be combined with desalination plant using seawater brine as the draw solution either in closed-loop or open-loop. This hybridization has multiple applications such as reducing the impact of discharging concentrated brine to sea, energy storage, and increase the recovery rate of the desalination. Power generation by DSPRO will reduce the energy consumption by the desalination processes. Waste heat from power plants can be used for the regeneration of the draw solution in the closed-loop DSPRO. Process modelling has been performed and shown promising results for DSPRO application for power generation.

A variable-capacity power system driven by geothermal energy: research methodology and preliminary experimental study

To match for the different temperature of the geothermal resource and strengthen the flexibility of organic Rankine cycle (ORC), this paper proposes a variable capacity power generation superstructure based on Flash and ORC for geothermal energy. A combined Flash-ORC experimental prototype is newly established to investigate its performance on both steady and dynamic conditions in this paper. Pressured hot water is adopted as the extensive worldwide existed hydrothermal geothermal resource, eliminating the influence of the used heat transfer oil on evaporating process. Important variables are investigated including the working fluid mass flow rate, loads quantity and outdoor environment of ORC subsystem in the preliminary experimental study. Firstly, steady experiment indicates that the maximum net power generation of ORC subsystem is 0.74 kW, revealing the existing optimal working fluid mass flow rate of the specific system. Secondly, dynamic on-off investigation of working fluid pump illustrates that ORC system has a certain extent self-adaption capacity and reliability. In addition, power generation increases with the decrease of the loads, and the condensing temperature makes a big influence on system performance when ORC using the cooling tower.

A Polywell Fusion Reactor Designed for Net Power Generation

A brief history of Polywell progress is recounted. The present PIC simulation explains why the most recent Polywell fusion reactor failed to produce fusion energy. Synchronized variations of multiple parameters would require DC power supplies, not available in historic model testing. Even with DC power, the simulation showed that the trapping of cold electrons would ruin plasma stability during start-up. A theoretical solution to this trapping problem was found in Russian literature describing diocotron-pumping of electrons out of a plasma trap at Kharkov Institute. In Polywell, diocotron-pumping required matching the depth of the potential-well to the electron-beam current falling on a special aperture installed in one of the electromagnets. With diocotron-pumping the reactor was simulated to reach steady-state, maximum-power operation in a few milliseconds of simulated time. These improvements, validated in simulating small-scale DD reactors, were scaled up by a factor of 30 to simulate a large, net-power reactor burning p + 11B fuel. Power-balance was estimated from a textbook formula for fusion power density by numerically integrating the power density. Unity power-balance required the size of the p + 11B reactor to be somewhat larger than ITER.

Regional variation in the mechanical properties and fibre-type composition of the rat extensor digitorum longus muscle.

What is the central question of this study? Mammalian muscle is typically heterogeneous in fibre-type distribution, with distinct regional variation in composition. The effects this might have on mechanical performance are largely unknown. What is the main finding and its importance? Contractile properties vary regionally within a heterogeneous muscle. The mixed extensor digitorum longus muscle has phenotypically distinct compartments that differ in their isometric twitch kinetics, the optimal cycle frequency for maximal power generation and fatigue resistance. The mechanisms underpinning the decline in performance during fatigue differ between compartments. Regional variation in mechanical performance suggests that regions of the extensor digitorum longus muscle might be differentially recruited during locomotion, depending upon functional demand. Fibre-type composition is heterogeneous, and distribution varies spatially in many muscles, indicating that there might be regional variation in recruitment and mechanical output. The rat extensor digitorum longus muscle is composed of predominantly fast-twitch fibres and exhibits a gradient in phenotype, resulting in oxidative medial (areal composition 24.3% type I/IIa) and glycolytic lateral (92.4% type IIx/IIb) compartments. Here, we investigated the variation in mechanical performance between the medial and lateral compartments during isometric, isotonic and cyclical contractions. Isometric tetanic stress and force-velocity relationships were similar in both compartments, but isometric twitch kinetics were slower in the medial compared with the lateral compartment. The medial compartment also had a lower optimal cycle frequency for maximal net power generation (11 versus 15Hz; P<0.05) attributable to slower isometric kinetics, resulting in a lower level of activation and reduced net work generation at higher cycle frequencies, compared with the lateral compartment. The more oxidative, medial compartment had higher fatigue resistance, maintaining net power 26% longer than the lateral compartment. The predominant mechanisms underpinning the decrease in net power varied between the compartments, resulting from an increase in the work to extend the muscle and from a reduction in work during shortening in the medial and lateral compartments, respectively. Regional variation in mechanical performance and resistance to fatigue within a mixed muscle suggests that a differential recruitment pattern is likely during locomotion, with the medial compartment being used during slow-speed locomotion and the lateral compartment during burst activities.

Bionic foot design: an inside view

Researchers in India have designed a physiologically controlled ankle prosthesis that is capable of mimicking the natural movements and flexibility of a human foot. To find out more about this promising device we spoke to Oishee Mazumder and her colleagues at Indian Institute of Engineering Science and Technology to find out more. The important considerations to take into account when designing ankle-foot prostheses are low cost, inclusion of a power saving mode and ensuring the foot is mechanically resilient in power-off mode. Commercially available ankle foot prostheses are completely passive, and consequently, their mechanical properties remain fixed with walking speed and terrain. However, human ankle stiffness actually varies within each gait cycle (stride) and also with walking speed, which must be taken into account in prosthetic design. Below-knee amputees who use passive ankle foot prostheses also exhibit non-symmetric gait patterns and high metabolic ambulatory rates. The primary challenges in this field are associated with size, weight, controlling parameters, sensor fusion, realisation in embedded platform and the final cost of the product. Our group aims to make user friendly prototypes with physiological control by using multimodal sensory input signals. Limitations of current prosthetic technology includes: inability to provide net power at the joints (passive prostheses), high cost and the absence of feedback systems. Also, loss of net power generation at the lower limb impairs the ability of the prosthetics to biomechanically restore normal locomotive functions during many locomotive activities, such as walking, running and jumping. The elevated metabolic demand and slower preferred speeds of transtibial amputees are likely to be the cause of conventional passive prosthetics being unable to produce power at the ankle. In our published Letter we report the design and development of a wearable, low-cost, low-power prosthetic active ankle foot. The foot is controlled by myoelectric, inertial and pressure sensors that are actuated by custom designed servo motors, thus ensuring natural ankle spring-like behaviour is created. Our reported system is adaptable to variation of cadence and different terrain. Most modern ankle-foot prostheses employ a single spring in their design, such as a carbon fibre leaf spring. The gait of an amputee who uses these passive compliant prostheses mimics the unaffected ankle during normal walking, but deviates from normal as walking speed increases. Common ankle design is mostly related with DC motor and proper spring actions. In the present development, spring stiffness is adjusted to control the motor action in each gait phase. Our design is a cost-effective solution for transtibial amputees, which will help them regain their lost mobility in a relatively small time span. The design concept that we have followed can also be utilised in gait analysis, orthotic design in spinal cord injury (lower body exoskeleton) and in rehabilitation devices. As an extension of the concept of myoelectric controlled active ankle foot prosthesis, we have already started on the development of a lower limb active exoskeleton and its control strategy for regenerating and enhancing mobility. Immediately, the device can be improved in several ways, such as by the introduction of a low-weight, high-strength carbon nanotube-based fibre structure, long-life packing sensors and the incorporation of compact light-weight actuators. In the long run, the knowledge that we have developed will be used to design lower body exoskeleton devices with intelligent ankle feet. Prosthetic ankle prototype with custom designed servo motor to enable amputees to have physiological control of the artificial limb. Labelled design of the fabricated ankle foot prosthetic prototype. The device is currently under clinical testing with testing already carried out on three subjects under the supervision of a qualified prosthesist. The remaining challenges that we have yet to address are the need to reduce the limbs, weight, incorporate an efficient actuator and improve the battery power. A completely new prototype is under development, which will take care of the described deficiencies of the existing system. Amputation in general often leads to loss of work and mental disturbance. Every amputee needs training and counselling to be habituated and comfortable with the prosthetic device. This requires frequent follow up in rehabilitation centres. In many cases, such extensive follow-ups are not possible and desired results are not achieved. To address this we would like to develop an electromyogram (EMG) based rehabilitation, which will serve dual-purpose of regenerating and strengthening EMG signals and provide interactive training for prosthetic use.

Energy-saving combination of N2 production, NH3 synthesis, and power generation

A novel integration of N2 production, NH3 synthesis, and power generation systems is designed to efficiently convert H2 to NH3. The integrated system employs the principles of exergy recovery and process integration to achieve high energy efficiency. The high-purity N2 output by the N2 production module is reacted with H2 in an NH3 synthesis module to produce NH3. In addition, O2-rich gas, which is a by-product, is utilized as an oxidant in the power-generation module. A single column is adopted in the N2 production module, and the feed stream is split into two and fed to the middle and bottom of the column. In our tests with the N2 production module, the two operating parameters of bottom-feed ratio and refed-stream ratio were evaluated in terms of the energy consumed, N2 purity, and O2 molar fraction in O2-rich gas. Compared with previous studies on N2 production systems, our N2 production module can reduce energy consumption by about 43% (3.27 MW compared with 5.76 MW to produce 1 tmol-N2 h−1). In the NH3 synthesis and power generation module, the two operating parameters of conversion rate per pass and purged-stream ratio are also evaluated. The calculation results show that a high conversion rate per pass and low purged-stream ratio increase the total energy efficiency, which includes NH3 production efficiency and power generation efficiency. The highest total energy efficiency that can be achieved by the integrated system is 66.92%, which includes a NH3-production efficiency of 66.69% and a net power generation efficiency of 0.23%.

Exergy and economic analysis of organic Rankine cycle hybrid system utilizing biogas and solar energy in rural area of China

ABSTRACTDue to the existing huge biogas resource in the rural area of China, biogas is widely used for production and living. Cogeneration system provides an opportunity to realize the balanced utilization of the renewable energy such as biogas and solar energy. This article presented a numerical investigation of a hybrid energy-driven organic Rankine cycle (ORC) cogeneration system, involving a solar ORC and a biogas boiler. The biogas boiler with a module of solar parabolic trough collectors (PTCs) is employed to provide heat source to the ORC via two distinct intermediate pressurized circuits. The cogeneration supplied the power to the air-condition in summer condition and hot water, which is heated in the condenser, in winter condition. The system performance under the subcritical pressures has been assessed according to the energy–exergy and economic analysis with the organic working fluid R123. The effects of various parameters such as the evaporation and condensation temperatures on system performance were investigated. The net power generation efficiency of the cogeneration system is 11.17%, which is 25.8% higher than that of the base system at an evaporation temperature 110°C. The exergy efficiency of ORC system increases from 35.2% to 38.2%. Moreover, an economic analysis of the system is carried out. The results demonstrate that the profits generated from the reduction of biogas fuel and electricity consumption can lead to a significant saving, resulting in an approximate annual saving from $1,700 to $3,000. Finally, a case study based on the consideration of typical rural residence was performed, which needs a payback period of 7.8 years under the best case.

Influence of the pinch-point-temperature difference on the performance of the Preheat-parallel configuration for a low-temperature geothermally-fed CHP

In this work, we investigate the performance of the so-called Preheat-parallel CHP configuration, for the connection to a thermal network (TN). A low-temperature geothermal source (130°C), and the connection to a 75°C/50°C and a 75°C/35°C thermal network are considered. For a pure parallel CHP configuration, the brine delivers heat to the ORC and the thermal network in parallel. However, after having delivered heat to the ORC, the brine in the ORC branch still contains some energy which is not used. The Preheat-parallel configuration utilizes this heat to preheat the TN water before it enters the parallel branch, where the TN water is heated to the required supply temperature. The Preheat-parallel configuration is especially favorable when connected to a thermal network with a low return temperature, a large temperature difference between supply and return temperatures—thereby exploiting the preheating-effect—and for high heat demands.In this paper, we focus on the effect of the pinch-point-temperature difference (∆Tpinch) on the plant performance. ∆Tpinch is directly related with the size and cost of the heat exchangers and strongly influences the preheating-effect, which is the most characteristic feature of the Preheat-parallel configuration. First, we present the results of a detailed sensitivity analysis of ∆Tpinch. A higher ∆Tpinch results in a lower preheating-effect, a lower net power output and, correspondingly, lower plant efficiency. Furthermore, we compare the performance of the Preheat-parallel configuration with the convenient parallel and series CHP configurations. For all three configurations, the performance decreases with an increase of ∆Tpinch. For the considered thermal network requirements, the net power generation is the highest for the Preheat-parallel configuration. With respect to the parallel configuration, the gain in net power generation stays approximately constant (75°C/35°C TN) or decreases (75°C/50°C TN) with the imposed pinch-point-temperature difference. With respect to the series configuration, the gain in net power generation increases for a higher value of ∆Tpinch. This means that the impact of ∆Tpinch is the biggest for the series configuration, followed by the Preheat-parallel configuration, and that the impact on the performance of the parallel configuration is the smallest.

Development of air-cooled compact Organic Rankine Cycle power generation technology utilizing waste heat

As the effective utilization method of unused heat energy between 100 and 300 degree-C in the industrial sector, Organic Rankine Cycle (ORC) was selected from the viewpoint of high efficiency. The prototype of air-cooled compact ORC electric power generation system for 1kW class was evaluated in variation of the ambient temperature of condenser and the inlet temperature of expander. In the experimental results, at the expander inlet temperature of 175 degree-C and the ambient temperature of 20 degree-C for condenser, the generated power by the expander is 1,027W and the gross power generation efficiency is 10.3%. The net power generation efficiency, considering the input power of auxiliary equipment such as pumps and fans, is 9.0%. In the result of energy balance analysis, power consumptions of the pump and the fan are small and almost of the generated power is effectively available.

Performance correlations for characterizing the optimal off-design operation of an ORC power system

The goal of this work is to develop a set of simple correlations in order to characterize the optimal off-design performance of an ORC power system. To this end, a 2kWe ORC test rig is investigated as case study and a validated off-design model is used to assess the highest net power generation achievable by the system over its complete range of operating conditions. The off-design model employed is charge-sensitive (i.e. it imposes the total mass of refrigerant in the system) which permits to predict the ORC state (i.e. its pressures, temperatures, mass flow rates, subcooling, etc.) based on the system boundary conditions only. Since such modelling approach and optimization process are time-consuming, a set of simple analytical equations is developed so as to easily predict the optimal performance of the ORC systems.

Development of a Highly Efficient SOFC Module Using Two‐stage Stacks and a Fuel Regeneration Process

AbstractA solid oxide fuel cell (SOFC) module using two‐stage stacks and a fuel regeneration process between them was developed in this study for the first time, to the best of the authors' knowledge. Upon configuring the first‐stage and second‐stage stacks and a steam reformer between them in the SOFC module, a gross output power of DC 2.27 kW was generated with gross power generation efficiency of DC 69.2% (lower heating value (LHV)), at a total fuel utilization rate of 86.3%. This technology enables operation at a very high total fuel utilization rate even while operating the stacks at a moderate fuel utilization rate (below 70%). Considering an auxiliary device loss (6%) and inverter loss (5%), the net power generation efficiency is estimated to be AC 61.8% (LHV); hence, the module is considered to exhibit a high power generation efficiency. Further increases in the power generation efficiency could be realized in the future by removing the CO2 from the anode off‐gas during the fuel regeneration process and/or operating the stacks at higher temperatures by decreasing heat leakage from the module.

Enabling CCS via Low-temperature Geothermal Energy Integration for Fossil-fired Power Generation

Among the key barriers to commercial scale deployment is the cost associated with CO2 capture. This is particularly true for existing large, fossil-fired assets that account for a large fraction of the electricity generation fleet in developed nations, including the U.S. Fitting conventional combustion technologies with CO2 capture systems can carry an energy penalty of thirty percent or more, resulting in an increased price of power to the grid, as well as an overall decrease in net plant output. Taken together with the positive growth in demand for electricity, this implies a need for accelerated capital build-out in the power generation markets to accommodate both demand growth and decreased output at retrofitted plants. In this paper, the authors present the results of a study to assess the potential to use geothermal energy to provide boiler feedwater preheating, capturing efficiency improvements designed to offset the losses associated with CO2 capture. Based on NETL benchmark cases and subsequent analysis of the application using site-specific data from the North Valmy power plant, several cases for CO2 capture were evaluated. These included geothermally assisted MEA capture, CO2BOLs capture, and stand-alone hybrid power generation, compared with a baseline, no-geothermal case. Based on Case 10, and assuming 2.7 MMlb/h of geothermally sourced 150°C water, the parasitic power load associated with MEA capture could be offset by roughly seven percent, resulting in a small (∼1 percent) overall loss to net power generation, but at levelized costs of electricity similar to the no-geothermal CCS case. For the CO2BOLs case, the availability of 150 ˚C geothermal fluid could allow the facility to not only offset the net power decrease associated with CO2BOLs capture alone, but could increase nameplate capacity by two percent. The geothermally coupled CO2BOLs case also decreases LCOE by 0.75 ¢/kWh relative to the non-hybrid CO2BOLs case, with the improved performance over the MEA case driven by the lower regeneration temperature and associated duty for CO2BOLs relative to MEA.

Design and experimental validation of an adaptive control law to maximize the power generation of a small-scale waste heat recovery system

Increasing the energy efficiency of industrial processes is a challenge that involves, not only improving the methodologies for design and manufacturing, but optimizing performance during part-load operation and transient conditions. A well-adopted solution consists of developing waste heat recovery (WHR) systems based on Organic Rankine Cycle (ORC) power units. The highest efficiency for such cycle is obtained at low superheating values, corresponding to the situation where the system exhibits time-varying nonlinear dynamics, triggered by the fluctuating nature of the waste heat source. In this paper, an adaptive control law using the Model Predictive Control (MPC) framework is proposed. This work goes a step beyond most of the existing scientific works in the field of ORC power systems, since the MPC controller is implemented in a lab-scale prototype, and its performance compared against a gain-scheduled PID strategy. The experimental results show that the adaptive MPC outperforms the gain-scheduled PID based strategy, as it allows to accurately regulate the evaporating temperature, while keeping vapor condition at the inlet of the expander i.e., the superheating, in a safe operating range, thus increasing the net power generation.

Net thermoelectric power generation improvement through heat transfer optimization

Thermoelectric generation contributes to obtain a more sustainable energetic system giving its potential to harvest waste heat and convert it into electric power. In the present study a computational optimal net generation of 108.05MWh/year was produced out of the flue gases of a real tile furnace located in Spain (the equivalent to supply the energy to 31 Spanish dwellings). This maximum generation has been obtained through the optimization of the hot and cold heat exchangers, the number of thermoelectric modules (TEMs) installed and the mass flows of the refrigerants, including the temperature loss of the flue gases and the influence of the heat power to dissipate over the heat dissipators.The results are conclusive, the installation of more TEMs does not always imply higher thermoelectric generation, so the occupancy ratio (δ) has to be optimized. The optimal generation has been achieved covering the 42% of the surface of the chimney of the tile furnace with TEMs and using heat pipes on the cold side, which present smaller thermal resistances than the finned dissipators for similar consumptions of their fans. Moreover, the high influence of the consumption of the auxiliary equipment shows the importance of considering it to obtain realistic usable electric energy from real applications.

Retrofitting existing coal power plants through cofiring with hydrothermally treated empty fruit bunch and a novel integrated system

High-potential biomass residues from the palm oil industry such as palm kernel shells and empty fruit bunch (EFB) must be utilized with the appropriate technology to optimize its economic benefit and minimize the environmental impacts. In this study, the cofiring behavior of hydrothermally treated EFB (HT-EFB) with coal is analyzed in terms of thermal behavior including temperature distribution and the composition of gases produced (CO and CO2) through computational fluid dynamics. Several HT-EFB mass fractions are evaluated, i.e., 0%, 10%, 25%, and 50%. To complement this research, an experimental study is conducted to validate the simulation results. In general, an HT-EFB mass fraction in the range of 10–25% seems to be the most preferable cofiring condition. In addition, an integrated system is also proposed and evaluated including coal drying, HT treatment of EFB, cofiring, and power generation. Very low energy consumption during coal drying and HT treatment of EFB can be achieved. Finally, the net power generation efficiency of the proposed integrated system is approximately 40% including coal drying and HT treatment of EFB processes.

Energy use and carbon footprints differ dramatically for diverse wastewater-derived carbonaceous substrates: An integrated exploration of biokinetics and life-cycle assessment

Energy neutrality and reduction of carbon emissions are significant challenges to the enhanced sustainability of wastewater treatment plants (WWTPs). Harvesting energy from wastewater carbonaceous substrates can offset energy demands and enable net power generation; yet, there is limited research about how carbonaceous substrates influence energy and carbon implications of WWTPs with integrated energy recovery at systems-level. Consequently, this research uses biokinetics modelling and life cycle assessment philology to explore this notion, by tracing and assessing the quantitative flows of energy embodied or captured, and by exploring the carbon footprint throughout an energy-intensive activated sludge process with integrated energy recovery facilities. The results indicate that energy use and carbon footprint per cubic meter of wastewater treated, varies markedly with the carbon substrate. Compared with systems driven with proteins, carbohydrates or other short-chain fatty acids, systems fed with acetic acid realized energy neutrality with maximal net gain of power from methane combustion (0.198 kWh) and incineration of residual biosolids (0.153 kWh); and also achieved a negative carbon footprint (72.6 g CO2). The findings from this work help us to better understand and develop new technical schemes for improving the energy efficiency of WWTPs by repurposing the stream of carbon substrates across systems.

Energy and exergy evaluation of a tri-generation system driven by the geothermal energy

In this paper, a geothermal-based tri-generation energy system with three useful outputs is clearly developed to produce electricity, heating and hydrogen. To have a better view of the thermodynamic performance of the present integrated system, parametric studies upon the effects of geofluid mass flow rate, turbine inlet temperature and pressure on the energy and exergy efficiencies of the system are undertaken. Under the specified circumstances, the related efficiencies of energy and exergy for the overall system are estimated around 26.14 % and 44.45 %, respectively, while these efficiencies for this system with electricity and heating generation, amount to 25.32 % and 39.75 %, and these amounts for solely electricity generation are 6 % and 33.47 %, respectively. Also the amount of net electricity power and heating generation in specific design parameter values are estimated around 43.47 (kW) and 149.8 (kW), respectively. In addition, for every 10.4 kW of electrical energy consumption in the electrolysis unit, pure hydrogen will be produced at a rate of 0.2 kg/hour.

Comprehensive study on the role of eco-friendly working fluid properties on ORC performances

In the present study, the effects of various low-GWP fluid properties on organic Rankine cycle (ORC) performances are examined for low grade heat sources and an attempt is made to prepare a general guideline to compare working fluids for ORC based on their basic properties. Theoretical study on ORC is conducted to study the effects of various fluid properties on net power generation, thermal efficiency, turbo-machinery and heat exchanger compactness. The considered eco-friendly working fluids for ORC were shortlisted based on operational, environmental and safety criteria. Performance comparison between selected working fluids shows that ammonia is the best fluid in terms of net power generation and compactness of turbo-machineries, whereas n-Pentane is the best fluid in terms of thermal efficiency and heat exchangers compactness. Study shows that the molar mass, normal boiling point temperature, critical temperature and phase diagram characteristics have significant effect on cycle performance indexes. However, the effect of properties does not show any common criteria for best in terms of all performance indexes. Present study summarizes the required fluid properties to get individually best for all performance indexes, which will be useful for fluid comparison and selection for certain design target.

A novel integration of oxy-fuel cycle, high temperature solar cycle and LNG cold recovery – energy and exergy analysis

A novel integrated CO2 oxy-fuel transcritical and Rankine cycles with CO2 capturing is introduced and analyzed. Carbon dioxide (CO2) is used as working fluid which is extracted from the process in high pressure and liquid state. The process benefits from high-temperature solar cycle as heat source and LNG cold energy as heat sink. Solar energy is used in the oxy-fuel transcritical cycle as the evaporator heat source. In the same context, the required heat duty for LNG vaporization in the desired operating condition is provided by solar energy. 1.03×104kg·h−1 of CO2 is condensed by employing cold energy of LNG which increases the net electrical power. Parametric analysis is conducted for turbine inlet temperature (TIT), LNG flow rate and solar cycle operating parameters. Energy and exergy analysis are done to find out the better performance of the process. The obtained results indicate that, TIT and LNG flow rate have positive effects on the exergy efficiency and net electrical power generation. Also, by applying TIT about=900°C, concentrated parabolic collector area (ACPC) equal to 4.6m2, 3.89×105kg·h−1 of LNG and 7.13×104kW of absorbed high-temperature solar energy; the net electrical power about 43.5×103kW is generated. The energy and exergy efficiencies of the overall process are 57.2% and 60.7%, respectively.