Machine Learning Enhanced Spectroscopic Analysis: Towards Autonomous Chemical Mixture Characterization for Rapid Process Optimization

Autonomous chemical process development and optimization methods use algorithms to explore the operating parameter space based on feedback from experimentally determined exit stream compositions. Measuring the compositions of multicomponent streams...

Regulation Characteristics and Load Optimization of Pump-Turbine in Variable-Speed Operation

In order to improve the operating and regulation characteristics of the hydropower unit and to stabilize the load fluctuations, variable-speed pumped storage technology based on converters has been proposed and given more attention recently. However, different from the conventional units, due to the variability of operation conditions, variable-speed units need to develop a load optimization strategy in terms of operating parameter identification to ensure state matching for operation. Therefore, this paper proposes an optimization search step based on the model test curve, and the process of parameter optimization search is elaborated and calculated in the turbine operating condition and pump operating condition, respectively. A mathematical model of the turbine regulation system is established to analyze the influence of speed and guide vane related parameters on the regulation characteristics, and the achievable operating range and regulation capacity in the variable-speed condition is pointed out based on pump-turbine model test, as well as the advantages over the fixed-speed operation. The results show that by applying the load optimization method, the variable-speed unit can be significantly improved in terms of operating efficiency, especially at low head and low power conditions. Meanwhile, a certain range of active power regulation can be realized by the decoupling control of the converter and measuring the guide vane opening in both modes. The analysis of the model test verifies the effectiveness of the variable-speed regulation operation of pump-turbine and provides a reference for the design and operation of the variable-speed hydropower units.

The Effect of Compression Ratio on Performance of Generator Set Fuelled with Raw Biogas

In order to utilize a raw biogas as a fuel of generator set (gen-set), it is important to figure out optimum operating parameter of the gen-set, i.e. compression ratio. The present work aims to investigate the effect of compression ratio on performance of 3 kW gen-set fuelled with raw biogas and to obtain optimum compression ratio for operation of the gen-set on raw biogas. The gen-set used in the present work is bi-fuel engine, i.e. fuelled with gasoline or LPG. The performance of the engine fuelled with raw biogas in terms of brake power, brake torque, brake specific fuel consumption, and thermal efficiency is evaluated at compression ratio of 7.5, 8.5, 9.5, and 10.5. The work is carried out under electrical load of 240, 420, and 600 Watt. The result indicates that compression ratio affects the rotational speed, brake power, brake torque, brake specific fuel consumption, and thermal efficiency of the gen-set. Optimum compression ratio for the gen-set fuelled with raw biogas is 9.5. At the optimum compression ratio, maximum brake power, brake torque, and thermal efficiency of are 450.37 W, 1.66 Nm, and 46.93%, respectively. Minimum brake specific fuel is 0.59 kg/kWh at the optimum compression ratio.

Thermohydraulic Performance Optimization of Automobile Radiators Using Statistical Approaches

Automobile radiator which is one of the vital components used for engine cooling in vehicles, is expected to provide higher thermal performance without changing the exterior dimensions of the radiator with the development of engine technology. This situation necessitates changes in both design and operating parameters in the currently used radiator. In the present study, all fundamental parameters affecting the thermal and hydraulic performance of an automobile radiator are evaluated and optimized with statistical methods. Optimization study is carried out using Taguchi and ANOVA methods for two specified objective functions (heat transfer and pressure drop). The order of importance and impact rates for each design and operating parameter, the best and worst working conditions in terms of both target functions are determined. Air velocity, air inlet temperature, coolant inlet temperature and fin pitch are found to be the most effective parameters on the heat transfer with a contribution ratio of 88%. The best and worst working conditions are obtained for the heat transfer and under these working conditions, they are calculated as 43.68 kW and 1.63 kW, respectively. When the system is examined in terms of the pressure drop, the results show that the coolant flow rate and tube height have a great impact with a contribution ratio of 67.04% and 32.06%, respectively. Lastly, the maximum and minimum pressure drop within the studied operating condition range, are determined as 20.68 kPa and 0.12 kPa, respectively.

The Effect of Operating Parameters of Alkali Catalyzed Transesterification of Sunflower Oil With Methanol in the Presence of the Cosolvent Assisted by Hydrodynamic Cavitation on the Degree of Triglyceride Conversion

Method of independent variation of the value of one operating parameter has been used to investigate the effect of operating parameters on alkali-catalyzed transesterification of sunflower oil with methanol in presence of tetrahydrofuran (THF) as cosolvent, assisted by hydrodynamic cavitation (ACTC) on the value of the degree of triglyceride conversion (DTC). ACTC was performed by a venturi-type hydrodynamic cavitation reactor (VCR) of our construction. To determine the effect of ACTC on DTC following operating parameters were varied: reaction mixture inlet pressure (p1) from 202.3 kPa to 1013.2 kPa; methanol to oil molar ratio (M1) from M1=3 to M1=12; concentration of catalyst (Cc) from 0.3wt% to 1.5wt%; methanol to THF molar ratio (M2) from M2=1.25 to M2=2.0; temperature (T) from 20°C to 55°C, number of passes through the VCR (n) from n=1 to n=10. It was found, based on the obtained results, that: a) the values of DTC increase with the increase in p1, M1, Cc, and n, b) the values of the DTC decrease with the increase in T and c) maximum values of the DTC are obtained at Cc=1.0~1.1wt% and M2=1.5.

Algorithm for Evaluating Energy Detection Spectrum Sensing Performance of Cognitive Radio MIMO-OFDM Systems

Cognitive radio technology enables spectrum sensing (SS), which allows the secondary user (SU) to access vacant frequency bands in the periods when the primary user (PU) is not active. Due to its minute implementation complexity, the SS approach based on energy detection (ED) of the PU signal has been analyzed in this paper. Analyses were performed for detecting PU signals by the SU in communication systems exploiting multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) transmission technology. To perform the analyses, a new algorithm for simulating the ED process based on a square-law combining (SLC) technique was developed. The main contribution of the proposed algorithm is enabling comprehensive simulation analyses of ED performance based on the SLC method for versatile combinations of operating parameter characteristics for different working environments of MIMO-OFDM systems. The influence of a false alarm on the detection probability of PU signals impacted by operating parameters such as the signal-to-noise ratios, the number of samples, the PU transmit powers, the modulation types and the number of the PU transmit and SU receive branches of the MIMO-OFDM systems have been analyzed in the paper. Simulation analyses are performed by running the proposed algorithm, which enables precise selection of and variation in the operating parameters, the level of noise uncertainty and the detection threshold in different simulation scenarios. The presented analysis of the obtained simulation results indicates how the considered operating parameters impact the ED efficiency of symmetric and asymmetric MIMO-OFDM systems.

Experimental Studies of Rocket Fuels Oxygen--Hydrogen, Oxygen--Methane Ignition by a Semiconductor Laser

The paper presents results of experimental studies aimed at introducing laser ignition of fuel mixtures into aero-space design practice. The source of ignition energy was a semiconductor laser featuring fibre radiation output, operating in a quasi-continuous wave mode. We carried out experiments for oxygen--hydrogen and oxygen--methane fuel types. The purpose of our research was to demonstrate the fundamental possibility of implementing fuel ignition by means of this type of laser, using a rocket engine igniter and a low-thrust rocket engine as examples. Employing semiconductor lasers directly as an ignition source for fuel mixtures in aerospace technology is attractive as it may feasibly reduce the requirements for thermal conditions during operation of the laser ignition system on board a rocket or spacecraft, as well as expand the range of permissible vibration and shock loads. The paper presents experimental results that delineate operating parameter ranges and operation cyclograms for the devices under consideration that ensured stable ignition of oxygen--hydrogen and oxygen--methane fuel mixtures; we also list the required power parameters for a semiconductor laser. The investigation revealed the specifics of using a semiconductor laser-based ignition system, which will be useful in developing laser rocket launching devices, ensuring reliable repeated on-off functionality

Effective Alarm Management System for Process Safety and Plant Reliability

Poorly managed alarms and improper design of alarm system have contribute to major industrial incident. Some examples are fire explosion on Milford Haven, 24th July 1994 where it flooded by alarms at the rate of one every two or three seconds resulting operator cancelling those alarms due to the nuisance (Health and Safety Executive, 1997), other case was from Texas City Refinery explosion, 23rd March 2005 where the high level alarm was ignore while the secondary high alarm was faulty (BP Executive Summary, 2005), and recent incident of Fatal Gas Well Blowout in Pryor Trust gas well Pittsburgh Country 22nd January 2018 where the entire alarm system was disabled by rig personnel due to nuisance condition (U.S. Chemical Safety and Hazard Investigation Board,2019). Banyu Urip facility have put significant effort on improving alarm effectiveness. This paper describes Banyu Urip alarm management workflow and improvement consisting of data collection, alarm analysis (identify bad actor), short term repair/improvement, alarm review & rationalization, management of change process, re-evaluation of operating envelopes, and high focus for implementation and stewardship. Alarm management tools and dashboard significantly helps the process. There are 4 KPIs that periodically reviewed: number of alarm rate, standing alarm, shelved alarm and critical operating parameter. This paper also provide Banyu Urip plant alarm management journey that started by first cold eyes review found imbalance of 3 panel operator load. Reconfigure asset assignment significantly improve the alarm rate as well as plant stability. The journey continue by multiple approach depend on the case of alarm such as nuisance alarm and standing alarm consisting alarm rationalization, alarm suppression logic, equipment out Of service logic, time delay implementation, control loop tuning, and deadband setting. Other than that, manual shelving process also utilized for nuisance alarms short term action caused by equipment or sensor problem, as long as mitigation exists, communicated on every shift handover and directly followed up to maintenance order list. There are also some cases where known equipment issues waiting for long term resolution causing continuous alarms. Risk screening process help all parties aware on incremental risk during the interim period. Having above alarm management improvement workflow, CPF site team have able to reduce down the alarm rate to stable criteria (<12 / hours) and standing alarm continue to decrease to 10/console. Finally, this paper also describes how alarm management practices can be also utilized as supplementary surveillance dashboard to improve plant reliability