Due to the global warming, climate treaty regulations and credits have been enhanced. As a result, the Carbon Capture & Storage (CCS) technologies have been emerged. In this study, it is presented that is separating the CO 2 from Air by vortex generator. The vortex tube is a device to separate inlet gases to hotter and colder mixture than inlet by energy separation technology. In this study, the vortex tube is applied to CO 2 gas separation from air that is investigated under atmospheric temperature. Prior to feasibility experiment, transient response shows that the temperature separation is settled down in 3000 seconds. Experimental parameters of gas separation are pressures and concentrations of CO 2 that is mixed with air. Results show that CO 2 gas separation is proportional to operating temperature. The percentage of CO 2 gas separation is 7.4 % at 3bar g and cold mass fraction of 0.6. The gas separation is also affected by inlet CO 2 concentration.

In this paper, a 3-D numerical model is proposed to investigate the capability of generating high operating temperature for a modified solar cavity receiver in large-scale dish Stirling system. The proposed model aims to evaluate the influence of radiation intensity on the cavity receiver performance. The properties of the heat transfer fluid in the pipe and heat transfer losses of the receiver are investigated by varying the direct normal irradiance from 400W/m 2 to 1000W/m 2 . The temperature of heat transfer fluid, as well as the effect of radiation intensity on the heat transfer losses have been critically presented and discussed. The simulation results reveal that the heat transfer fluid temperature and thermal efficiency of the receiver are significantly influenced by different radiation flux. With the increase of radiation intensity, the efficiency of the receiver will firstly increase, then drops after reaching the highest point. The outlet working fluid temperature of the pipe will be increased consistently. The results of the simulations show that the designed cylindrical receiver used in dish Stirling system is capable to achieve the targeted outlet temperature and heat transfer efficiency, with an acceptable pressure drop.

A steady state model of a supercritical organic Rankine cycle (SORC) was created in MATLAB and validated. Fluid properties were obtained using NIST REFPROP. Various working fluids were tested, including pentane (R601), isopentane (R601a), butane (R600), isobutane (R600a), butene, and cis-butene. Pentane and isopentane have not been of focus for SORCS at these temperatures. Varying turbine inlet temperatures ranging from 170 to 240°C were tested with the heat source provided by a medium temperature geothermal reservoir. A parametric analysis was performed on varying inlet pressure and turbine inlet temperature in comparison to first law efficiency, second law efficiency, effectiveness, and net work produced to analyze the overall and exergetic performance of each fluid. Optimum first law efficiency ranged from 17 to 22%. Cis-butene and pentane performed the best in all performance factors analyzed. Pentane and isopentane performed the best at pressures near or below their critical point. It was also found that near the critical temperature, a subcritical ORC has better performance than an SORC. This study is beneficial for not only geothermal energy but for applications that can provide operating temperatures between 170 to 240°C.

The heat flux on the receiver tube is non-uniform because of uneven solar flux and receiver structure, which causes overheating and thermal stress failure of receiver and affected safe operations of the Concentrated Solar Power (CSP) system. In order to reduce the temperature difference in receiver tube wall and improve the efficiency of CSP system, the ternary eutectic salt LiF-NaF-KF (46.5-11.5-42 wt.%, hereafter FLiNaK), which has a better high thermal stability than that of nitrate salts at operating temperature of 900 °C, is selected as HTF, and heat transfer performance of FLiNaK in a corrugated receive tube with non-uniform heat flux is simulated by CFD software in the present work. The numerical results reveal that the non-uniform heat flux has a great influence on the temperature distributions of the receive tube and FLiNaK salt. Compared with the result of bare tube, the corrugated tube can not only significantly reduce the temperature difference in tube wall and salt by improving the uniformity of temperature distribution but also enhance the heat transfer of the salt, where the heat transfer coefficient increases with the Reynolds number and heat flux. Moreover, the enhanced effect of the corrugated tube depends on both the pitch and the height of ridges. It is found that the heat transfer coefficient of the salt gets a maximum when the ratio of the height of ridge to the pitch is 0.2. The research presented here may provide guidelines for design optimization of receiver tube in CSP system.

The outer walls of insulated pipes are susceptible to corrosion if the insulation stays wet for long periods of time. Corroded pipes have the potential for bursting without warning, releasing steam or combustibles and insulation debris which may contain asbestos, requiring significant cleanup and repairs. Managing the associated risks requires the consideration of a number of factors such as corrosion rates, examination methods, prioritization of inspection locations, and fitness for service evaluation and repair methods. A number of factors affect the corrosion rate such as pipe material and geometry, proximity to saltwater environments, local weather, and prevailing wind directions, as well as insulation type and condition. Some locations on the piping system require additional scrutiny, such as at pipe supports where rain water can cascade down hanger rods and into openings in the insulation, and at the bottom of vertical pipe runs where moisture is prone to becoming trapped in the insulation cladding. To prioritize inspection locations, risk factors such as exposure of personnel, the potential amount of energy released, the postulated corrosion rate and failure potential based on pressure and temperature need to be taken into account. The most susceptible materials are carbon and low alloy steel. Pressurized dead leg small bore pipes are of concern due to the small wall thickness and low operating temperatures that do not provide an opportunity to dry out the insulation. Digital Radiography Testing (DRT) through insulation provides excellent results for most 6” or less diameter piping systems. Highly sensitive digital exposure plates require less radiation compared to conventional Radiography, resulting in small radiation safety zones that allow work in surrounding areas to continue during inspection. The technique is effective for the evaluation of corroding fillet welds and threaded connections, and provides a digitized image that is database friendly. It provides information on pipe diameter and schedule, which aids in the preparation of repair sketches and bill of materials before an outage occurs. Repair options include replacement and operational changes which allow abandonment as well as improvements or elimination of insulation. Corrosion Under Insulation (CUI) damage is a significant issue at some plant sites where limited run time doesn’t allow the insulation to dry. In the near future, older, less economic base loaded plants that will run less frequently may fall into this category. To evaluate risk, the probability of failure needs to be considered with its potential consequence. For a pipe with CUI damage, probability of failure is dependent on the corrosion rate, pressure, pipe diameter, and thickness. The consequences are a potential injury and lost production.

Nearly all states now have renewable portfolio standards (RPS) requiring electricity suppliers to produce a certain fraction of their electricity using renewable sources. Many renewable energy technologies have been developed to contribute to RPS requirements, but these technologies lack the advantage of being a dispatchable source which would give a grid operator the ability to quickly augment power output on demand. Gas turbines burning biofuels can meet the need of being dispatchable while using renewable fuels. However, traditional combustion of liquid fuels would not meet the pollution levels of modern dry, low emission (DLE) gas turbines burning natural gas without extensive back-end clean-up. A Lean, Premixed, Prevaporized (LPP) combustion technology has been developed to vaporize liquid ethanol and blend it with natural gas creating a mixture which can be burned in practically any combustion device in place of ordinary natural gas. The LPP technology delivers a clean-burning gas which is able to fuel a gas turbine engine with no alterations made to the combustor hardware. Further, the fraction of ethanol blended in the LPP gas can be quickly modulated to maintain the supplier’s overall renewable quotient to balance fluctuations in power output of less reliable renewable power sources such as wind and solar. The LPP technology has successfully demonstrated over 1,000 hours of dispatchable power generation on a 30 kW Capstone C30 microturbine using vaporized liquid fuels. The full range of fuel mixtures ranging from 100% methane with no ethanol addition to 100% ethanol with no methane addition have been burned in the demonstration engine. Emissions from ethanol/natural gas mixtures have been comparable to baseline natural gas emissions of 3 ppm NO x and 30 ppm CO. Waste heat from the combustor exhaust is recovered in an indirect heat exchanger and is used to vaporize the ethanol as it is blended with natural gas. This design allows for startup on natural gas and blending of vaporized ethanol once the heat exchanger has reached its operating temperature.

Operating temperature information was gathered using thermocouples installed on the outside of an existing high pressure feedwater heater (FWH). The operating data was collected to demonstrate the basis for the evaluation of the operational effectiveness of the heater especially during rapid load changes. This information provides insight into the selection of shell side design temperatures of the skirt and shell sections of a feedwater heater. This direct measurement of the temperature was useful in evaluating the appropriateness of both skirt and shell design temperatures selected by standard HEI practice. Also, consideration will be given to upgraded turbines and their impact on the design temperatures and pressures of existing FWH(s).

Examination of the effect of toluene and carbon dioxide accompanying acid gases (mainly H 2 S) in the sulfur recovery process is very critical to determine the optimum operating temperature for enhanced sulfur recovery. Experimental and simulation were used to quantify the conversion efficiency with the addition of different amounts of toluene and carbon dioxide/toluene mixtures to the H 2 S gas stream. The results showed similar trends between predictions and experimental data, which revealed a decrease in conversion efficiency with increase in toluene or carbon dioxide/toluene addition to the H 2 S gas stream in a reactor. Further simulations were carried out to seek for the effect of toluene and CO 2 addition to acid gas stream on the more favorable operating temperature of the reactor. The results showed that toluene increases the optimum reactor temperature at which enhanced sulfur recovery occurs, whereas it reduces the optimum operating temperature in the presence of CO 2 . The presence of toluene and CO 2 in the acid gas stream affects the sulfur recovery efficiency by altering the optimum temperature of the reactor. These results reveal the importance of reactor temperature and its excursion on sulfur recovery in a Claus process. The effect of mean reactor temperature and its role on detailed chemical speciation from within the reactor as well as the role of key species formed in the process on sulfur recovery are presented.

One of the current engineering challenges is to design next generation (Generation IV) Nuclear Power Plants (NPPs) with significantly higher thermal efficiencies compared to those of current NPPs to match or at least to be close to thermal efficiencies reached at thermal power plants (43–55%). A Sodium-cooled Fast Reactor (SFR) is one of six concepts considered under the Generation IV International Forum (GIF). This concept is the only one from the Generation IV reactors, which is actually in operation in Russia. In general, there are 3 possibilities for an SFR in terms of the secondary cycle: 1. Subcritical-pressure Rankine-“steam”-cycle through a heat exchanger (current approach used in Russian and Japanese power reactors). 2. Supercritical-pressure Rankine-“steam”-cycle through a heat exchanger (new approach). 3. Supercritical-pressure CO 2 Brayton-gas-turbine-cycle through a heat exchanger (US approach). The BN-600 reactor is a sodium-cooled fast-breeder reactor built at the Beloyarsk NPP in Russia. It has been in operation since 1980 and adopts the secondary subcritical-pressure Rankine-“steam”-cycle with heat regeneration. Steam extractions are taken from High-Pressure (HP), Intermediate-Pressure (IP) and Low-Pressure (LP) turbines. The basic method of increasing the thermal efficiency of power plants is to improve it by increasing the operating pressure and temperature. With the advent of modern super alloys, the Rankine-“steam”-cycle has progressed into the supercritical region of the coolant and is generating net efficiencies into the mid 40% range. Calculations of thermal efficiency of a secondary sub- and supercritical-pressure Rankine-“steam”-cycle with heat regeneration are presented in the paper. The Brayton-gas-turbine cycle is under consideration for future nuclear power reactors. The higher operating temperatures will be achieved, the higher thermal efficiency will be. Supercritical CO 2 cycle is a new approach in Brayton-gas-turbine cycle. Carbon dioxide has a critical pressure of 7.38 MPa and a critical temperature of 31.0°C, which is significantly less than that of water (22.064 MPa and 373.95°C). However, liquid sodium is more compatible with SC CO 2 than with water. Therefore, thermal efficiency of this SC CO 2 cycle is also calculated.

Flow Accelerated Corrosion (FAC) is a fundamental problem for nuclear, fossil, and combined cycle power plants which can result in the loss of power generation, damage to equipment, and personnel injury. These documented events and failures have attracted the attention of utilities, industry groups, and regulatory agencies. The economic impact of FAC in terms of lost power, lost revenue, damaged equipment and components, and personnel injury has gained increased attention. The mechanism of FAC involves the formation and removal of the protective oxide layer from the inside surface of the pipe or equipment. This process occurs in carbon steel piping systems, tanks, and vessels. The FAC process is influenced by flow rate, pH, oxygen content, operating temperature, material of construction, and piping configuration. To oversee and manage Flow Accelerated Corrosion (FAC) in power plants, utilities have assigned personnel the responsibility to manage the FAC program either at the corporate level or a site representative or both. One of the keys in managing FAC is the relationship, interface, and communication with the other disciplines within the organization. Some of these disciplines include Management, Operations, Maintenance, Design Engineering, System Engineering, Water Chemistry, Plant Documentation, and Non-Destructive Examination (NDE). Their responsibilities within the organization and to each other are critical in keeping the plant on-line and minimizing personnel injury. In addition, it is the foundation for maintaining an effective Flow Accelerated Corrosion Program. These relationships and responsibilities within the FAC Program will be discussed in this paper.

The connection between combined power and heat generation, and the concept of distributed generation is a relevant issue viz. improvement of the overall efficiency of energy conversion and distribution. In this context, the use of biomass may be of particular interest due to its potentially very low CO 2 emissions as well as low kWh production cost with respect to other renewable energy sources. Traditional methods to convert biomass involve micro-turbines or steam power plants. However, both electrical and overall efficiencies may not be particularly high for both technological and thermodynamic reasons; the latter being hard to supersede. High temperature Solid Oxide Fuel Cells (SOFCs) offer an attractive solution because they are characterized by electrical efficiencies in the range of 35% to 48% [1], and present a significant potential for integrating with the biomass gasification process; thus, exploiting advantages of high operating temperatures. Moreover, thermal integration is of prime importance. In fact, optimal management of thermal integration may allow operation with high moisture content feedstocks and with high water concentration in the SOFC; thus, promoting further hydrogen production via the water gas shift reaction [2]. In this paper, an integrated solid oxide fuel cell-gasifier system is modeled to identify the main effects on fuel cell performance under several operating conditions in terms of biomass flow rates and moisture contents. The SOFC and the gasifier are modeled by a zero dimensional approach to perform a sensitivity analysis with a numerical tool which requires less computational effort compared to those previously presented. The thermochemical phenomena are taken into account with a high degree of detail, and model validation is also showed via comparison with literature available data. Results highlight the impact of biomass feedstock and its moisture content on the electrical current density value. Final performance depends on the interaction among gasifier thermal sustainability, SOFC operating temperature and chemical equilibrium concentrations, via water gas shift reactions. In particular, it has been shown that thermal integration allows operation with higher moisture content biomass, thereby further exploiting H 2 O conversion into H 2 via water gas shift reactions and high fuel utilization operating conditions. The importance of thermal integration and advanced control of SOFC based biomass fueled systems is demonstrated by this study, as well as the use of a fast and reliable zero-dimensional modeling for system design and control purpose.

The green house effect by carbon dioxide issue would make better recognizing the importance of efficient use of energy in terms of high energy conservation measures. Accordingly, attention is drawn to the Stirling cycle machine, which is a perfect Freon free and efficient machine. Most Stirling engines operate in temperature ranges in which the temperature difference between the heat source and heat sink is between 100 K and 700 K, with the room temperature being at the lower end of the operating temperature range. However, information available on engines that utilize the room temperature as the heat source and the ultra-low temperature of liquid nitrogen as the heat sink is scarce. Engines that operate within such temperature ranges are called cryogenic heat engines. If their practical applications are realized, energy that has hitherto been wasted during the use of ultra-low-temperature media can be recovered in the form of electrical energy. We have designed and developed a 500 W class Stirling machine as a cryogenic engine. This paper presents some operating characteristics.