Cycle performance of Cu-based oxygen carrier based on a chemical-looping combustion process

The cycle life of oxygen carrier（OC） is crucial to the practical applications of chemical looping combustion（CLC）. Cycle performance of Cu/SiO2 prepared with a mechanical mixing method was evaluated based on a CLC process characterized with an added methane steam reforming step. The Cu/SiO2 exhibited high redox reactivity in the initial cycles, while the performance degraded with cycle number. Through characterization of the degraded Cu/SiO2, the performance degradation was mainly caused by the secondary particles＇ fragmentation and the fine particles＇ local agglomeration, which worsened the distribution and diffusion of the reactive gases in the packed bed. A regeneration method of the degraded OC based on re-granulation has been proposed, and its mechanism has been illustrated. With this method, the performance of the degraded OC through 420 redox cycles was recovered to a level close to the initial one.

Thermal performance analysis of advanced partial gasification combined cycle

This paper presents the thermodynamic performance analysis and comparison of four kinds of advanced pressurized fluidized bed combustion combined cycle (APFBC-CC) system schemes, two based on pressurized fluidized bed (PFB) combustion and the other two based on atmospheric circulating fluidized bed (CFB) combustion. The results show that the first scheme avoids high temperature gas filter, but has the lower cycle efficiency and syngas heating value. The second scheme can gain the highest cycle efficiency, however it is better to now lower the filter operating temperature. The third and fourth schemes, based on CFB, have lower efficiencies than the second one. But the fourth one, with preheating air/steam for gasification, can obtain the highest heating value of syngas and gain higher efficiency than the third one.

Simulation and Experiment for Oxygen-enriched Combustion Engine Using Liquid Oxygen to Solidify CO2

For capturing and recycling of CO2 in the internal combustion engine, Rankle cycle engine can reduce the exhaust pollutants effectively under the condition of ensuring the engine thermal efficiency by using the techniques of spraying water in the cylinder and optimizing the ignition advance angle. However, due to the water spray nozzle need to be installed on the cylinder, which increases the cylinder head design difficulty and makes the combustion conditions become more complicated. In this paper, a new method is presented to carry out the closing inlet and exhaust system for internal combustion engines. The proposed new method uses liquid oxygen to solidify part of cooled CO2 from exhaust system into dry ice and the liquid oxygen turns into gas oxygen which is sent to inlet system. The other part of CO2 is sent to inlet system and mixed with oxygen, which can reduce the oxygen-enriched combustion detonation tendency and make combustion stable. Computing grid of the IP52FMI single-cylinder four-stroke gasoline-engine is established according to the actual shape of the combustion chamber using KIVA-3V program. The effects of exhaust gas recirculation （EGR） rate are analyzed on the temperatures, the pressures and the instantaneous heat release rates when the EGR rate is more than 8%. The possibility of enclosing intake and exhaust system for engine is verified. The carbon dioxide trapping device is designed and the IP52FMI engine is transformed and the CO2 capture experiment is carried out. The experimental results show that when the EGR rate is 36% for the optimum EGR rate. When the liquid oxygen of 35.80-437.40 g is imported into the device and last 1-20 min, respectively, 21.50-701.30 g dry ice is obtained. This research proposes a new design method which can capture CO2 for vehicular internal combustion engine.

A Review of Throttling Technology Development for Large-Thrust Liquid Rocket Engines

Throttling of large-thrust liquid rocket engines,which can improve mission adaptability of a carrier rocket,reduce risk and facilitate rocket recovery,is a key technology for current and future space development.This paper summarizes the state of the art and trends of throttling technology for large-thrust liquid rocket engines at home and abroad.According to the working principles of propulsion for rocket engines,throttling the propellant flow rate is a major way of adjusting thrust,and regulation devices along with adjustable injectors are primary measures of throttling propellant flow rates.This paper clarifies the working principles of typical regulation devices and adjustable injectors,introduces the regulation schemes of typical large-thrust engines such as YF-100,RD-170,and SSME,and summarizes the main characteristics of current throttleable large-thrust engines.Finally,critical technologies and development trends of throttling are discussed,including combustion stability and reliable cooling of thrust chambers at low thrust levels,turbopump stability,and stable regulation and precise control in a wide range of operating conditions.

Effects of Vessel and Water Temperatures on Direct Injection in Internal Combustion Rankine Cycle Engines

This study focused on the effects of vessel and water temperatures on direct injection in internal combustion Rankine cycle engines through experimental and numerical methods.First,a study was carried out with schlieren photography using a high-speed camera for simultaneous liquid–gas diagnoses.Water was directly injected into a constant-volume vessel that provided stable boundaries.We wrote a MATLAB program to calculate spray tip penetration and cone angle from the images.For the further extension of boundary conditions,a numerical model was established and calibrated in AVL-FIRE for the thorough analysis of injection characteristics.Both experimental and numerical results indicated that injection and vessel temperatures have different effects on spray tip penetration.An increase in injected water temperature leads to shorter spray tip penetration,while the spray tip penetration increases with increasing vessel temperature.However,increased injection and vessel temperatures can both decrease the spray cone angle.Moreover,the simulation results also suggested that heat conduction is a main factor in boosting evaporation under top dead center conditions.When the internal energy of water parcels surges,these parcels evaporate immediately.These results are helpful and crucial for internal combustion engines equipped with direct water injection technology.