Supply Pressure Research Articles

Theoretical and Experimental Investigation of Porous Tilting Pad Gas Bearings with Hermetic Squeeze Film Dampers Based on Multilayer Diaphragm Structure

A novel porous tilting pad gas bearing (PTPGB) with hermetic squeeze film dampers based on multilayer diaphragm structure (MLD-HSFD) is proposed for oil-free turbomachinery. A dynamic model of MLD-HSFDs including the frequency dependence effect is presented by considering the compressibility of the damper fluid. An experimental test rig was assembled to measure the performance of MLD-HSFDs. The model predicts well the test data, including the frequency dependence of force coefficients. A comprehensive theoretical model of PTPGBs with MLD-HSFDs is proposed based on the implementation of the isothermal compressible Reynolds equation coupled to a flexible support and porous models. The effects of thickness of diaphragms thickness, bearing clearance, and supply pressure on bearing performance are discussed.

Vibration characteristics control of hybrid radial gas foil bearing-rotor system: Simulation and experiment

Currently, tiny, high-speed rotating machines frequently employ air foil bearings. Air is employed as the working medium, however, when the rotor speed is high, the rigidity of the air film is insufficient, which restricts the usage of air foil bearings. This study utilizes the external gas supply method of hydrostatic gas bearings to strengthen the air film stiffness of air foil bearings. The original air foil bearings are combined with external gas supply piping to create the hybrid gas foil bearing(HGFB), which may be utilized to increase the air film support stiffness of the bearings through the external gas supply. Additionally, by altering the gas supply pressure, this bearing may be used to actively manage the vibration characteristics of the shaft system, allowing the bearing performance to be adjusted to changing operating conditions. The static and dynamic properties of the HGFB with a 24 mm diameter are solved in this study using Newton's iterative approach and the finite difference method. The bearing-rotor system is modeled using this information. An Analysis is done on the impact of various air supply pressures and throttle hole widths on bearing performance and vibration characteristics of the shaft system. In this article, the vibration parameters of the bearing-rotor system are tested using an open-loop control test. The open-loop control experiment on the vibration response of the bearing-rotor system is performed using HGFBs with orifice sizes of 0 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm. The experimental results confirm the accuracy of the simulation results. Correspondingly, this paper conducted closed-loop control comparison experiments on the vibration properties of the bearing-rotor system using the PID control method and the fuzzy PID control method in succession. It then evaluated the control effect of the two control strategies on the vibration of the bearing-rotor system and managed to improve the conventional PID control method used for gas bearings.

Experimental studies on novel multi tubular reactor with shell having integrated buffer storage

This study concentrates on experimental analysis of a large scale metal hydride based hydrogen storage reactor having 50 kg LaNi5. In order to cater the heat transfer limitations of hydrogen storage in large scale systems, the present design have been developed as multi tubular reactor with shell having integrated buffer storage configuration with 7 tubes supported by means of 4 baffles having total 50 kg LaNi5 distributed equally among them and water as heat transfer fluid flows across the shell for heat transfer. The experimental study was performed for studying the absorption and desorption performance of the present hydrogen reactor wherein in case of absorption the parameters varied were HTF flow rate at 30 °C and supply pressure of hydrogen and in case of desorption which was carried out at atmospheric pressure, HTF flow rate and HTF temperature were varied. The metal hydride reactor reversibly stores 680 g of hydrogen amounting to 1.34 wt% of gravimetric capacity of metal hydride and equivalent energy storage of 10.4 MJ. In case of absorption, when the flow rate selected was 20 LPM the absorption time for 90 % reaction completion was observed to be 1286 s (21.4 min) at 30 bar H2 supply pressure. In case of desorption studies, it was observed that the varying flow rate from 15 to 25 LPM has negligible effect on hydrogen desorption hence 15 LPM was selected as flow rate for further desorption experiments. Further increasing HTF temperature from 60 °C to 80 °C improves the performance significantly.

Printability of inkjet according to supply pressure

To obtain uniform and high-resolution jetting, the drop-on-demand inkjet can be operated with various physical properties of inks. To determine how supply pressure control affects the stability of the jetting, an experimental study was conducted on eight model inks in a range of Z number (1 < Z < 17). The velocity and volume of drop were measured by a visualization method to analyze the performance of piezoelectric inkjet head. Increasing negative supply pressure reduced both velocity and volume. The decline of volume was uniform regardless of driving voltage, whereas the decline of velocity increased with decreasing driving voltage. The printability diagram of Z–We was derived to analyze the jetting behavior according to the ink properties, such as viscosity and surface tension, and operating conditions, such as driving voltage and supply pressure. For dimensionless numbers, Z and We, the surface tension term can be compensated by the supplementary Laplace pressure force generated by the supply pressure. In the printability diagram of the modified Z* and We*, the suppression of the satellite drop formation by negative supply pressure can be identified as a shift from the outer to the inner stable region. The critical aspect ratio at the pinch-off was estimated from the Taylor–Culick analysis of the liquid filament breakup. The damping time of residual vibration was measured according to the supply pressure within the printable range. We conclude that control of the supply pressure with slight droplet velocity and volume reduction can improve the printing stability and frequency.

A chemical kinetic analysis: Influence of post-flame chemistry, combustion pressure, premixing degree (fully premixed to non-premixed), and secondary air supply on NOx emissions from NH3/CH4-air combustion

Numerous studies assessed the viability of ammonia blends for the wide-scale application of ammonia in carbon-free energy systems. NOx emissions from ammonia combustion are the primary concern constraining the adoption of NH3 as a fuel. The present study explores the effect of post-flame chemistry, combustion pressure, reactant-mixing (premixing degree), and secondary air supply on NOx emissions from NH3/CH4 swirl flame. Furthermore, an extensive chemical kinetic analysis is carried out using the rate of production and sensitivity analyses to study NOx formation and destruction with the above-discussed techniques. The present study adopts the NH3/CH4 reaction model developed by Okafor et al. and a PSR-PFR chemical reactor network for predicting the NOx formation chemistry in NH3/CH4-air combustion. The analyses are conducted for the values of ammonia heat fraction in the fuel mixture (ENH3) = 0.1–0.3 and equivalence ratio (ϕ) = 0.6–1.4. The present work suggests that providing a post-flame zone is advantageous in reducing both NOx and NH3 emissions, especially for rich NH3/CH4 flames. Increasing the combustion pressure to achieve low NOx without significant ammonia slip appears to be a viable method for NH3/CH4 flames with ϕ < 1.2. Adopting a non-premixed injection mode is a feasible low NOx combustion technique for 0.9 < ϕ < 1.2, especially for higher ammonia fractions in the fuel mixture. An excess air supply of 10% reduces the NOx emissions for fuel-lean conditions (ϕ < 0.9) with a negligible rise in unburnt NH3 emissions under atmospheric conditions.

Research on roughness prediction model of robotic sanding carbon fiber reinforced plastics

By taking a pneumatic eccentric grinder and round sandpapers as research objects, the modeling method is proposed to accurately predict the surface roughness of robotic sanding carbon fiber reinforced plastic parts. A four-factor, the four-level orthogonal experiment was conducted which took four process parameters into account: pressing force, feeding speed, grit size, and supply air pressure. The multiple linear regression analysis method was then applied to create a roughness prediction model. Furthermore, accuracy validation results show that the model’s prediction error is within ±9%.

Secondary Frequency Regulation Control Strategy with Electric Vehicles Considering User Travel Uncertainty

The premise of electric vehicles (EVs) participating in the frequency regulation (FR) of power systems is to satisfy the charging demands of users. In view of problems such as the uncertainty of EV users’ departure time and the increase in power supply pressure due to disordered charging in the frequency regulation process of EV clusters, a secondary frequency regulation control strategy with EVs considering user travel uncertainty is proposed. Firstly, EV charging history was analyzed, a reliability parameter was introduced to describe the user travel uncertainty, and an individual EV controllable domain model based on reliability correction was constructed. Then, EV clusters were grouped according to charging urgency and state of charge (SOC), and the controllable capacity of EV clusters was determined. Finally, EV frequency regulation capability parameters and charging urgency parameters were defined to determine the EV frequency regulation priority list, combined with the EV state grouping and priority list, and the EV cluster frequency control strategy was proposed. The simulation results show that the proposed strategy can satisfy the charging demands of users under uncertain travel conditions, reduce the power supply pressure of the power system caused by EVs entering the forced charging state, and effectively suppress frequency deviation.

Thermal performance enhancement of metal hydride reactor for hydrogen storage with graphene oxide nanofluid: Model prediction with machine learning

Some metals and metal alloys can store gaseous hydrogen, making the storage of hydrogen in metal hydrides (MHs) possible. For the MH reactor to store hydrogen at a higher rate, improved heat transfer is required. The 2-D material graphene oxide (GO) attracted researchers’ attention due to its excellent thermal properties. The present work aims to improve heat transfer and hydrogen storage rate of the LaNi5 MH reactor. A 2-D axis-symmetric numerical model of the reactor is formed and simulated using COMSOL Multiphysics 5.6 software. Water and its based nanofluids (NFs), namely, GO, GO-SiO2 (50:50), GO-TiO2 (50:50), and Al2O3 are employed as heat transfer fluids (HTFs). The effect of inlet temperature and flow velocity of the HTF; and hydrogen supply pressure on the reactor performance is examined. The findings demonstrate that the storage rate is greatly improved by lowering the HTF inlet temperature; and increasing its inlet velocity and hydrogen supply pressure. In comparison to water and all other NFs, the GO NF with 1 vol% demonstrated comparatively better heat transfer. It reduces the duration by 61.7% of that of water to attain 90% hydrogen storage capacity at similar conditions. The data acquired in the numerical investigations were used to build a prediction metamodel using the evolutionary machine learning (ML) technique of gene expression programming (GEP).

Intelligent PID control of an industrial electro-hydraulic system

In this study, an intelligent PID (i-PID) controller is designed for position control of a nonlinear electro-hydraulic system with uncertain valve characteristics and supply pressure variations. The proposed controller uses estimation of ultra-local model of the system. To exhibit the capability of the proposed method, the controller parameters are optimized via the particle swarm optimization method through a nominal nonlinear model of the system. Then, the performance of the i-PID controller, parameters of which are optimized by using the nominal model, is examined under uncertainties caused by valve characteristics and supply pressure variations. Moreover, the friction between the piston and the hydraulic cylinder is also considered in experiments. A PID controller whose parameters are also optimized based on the same performance criteria, is used for comparison purposes with i-PID control both in simulations and experiments. Performance metrics of the controllers are examined and presented by employing two separate reference signals: Sine wave and ramp. The results show that the i-PID controller shows significantly better results than the classical PID controller in tracking the test signals under various supply pressures and valve modes.

Impact of water resources pricing mechanism on global agricultural economy based on CGE model

Abstract Water resource (WR) is a complex and interrelated system, which integrates human development and environment. Water price research is gradually carried out under the background of resource economy research, which is an important part of natural resource price research. The main goal of the water price mechanism is to solve the problem of water resource allocation under the pressure of water supply and demand and realize the sustainable development of agricultural economy (AE). Faced with the dual pressure of rising water demand and declining water supply, many regions have begun to reform the water price mechanism and use the CGE model for scientific and reasonable resource allocation. To this end, this paper analyzed the drawbacks and the factors of WR pricing mechanism and used the CGE (Computable General Equilibrium for short here) model to study the upper limit of the pricing of resources, and then analyzed the problems of WR CGE model in agriculture, and finally optimized the problems. According to the experimental analysis, the pricing mechanism of WR under the CGE model can reasonably allocate resources, reduce water demand and promote the development of AE.

Cylinder position control driven by pneumatic digital bridge circuit using a fuzzy algorithm under large stroke and varying load conditions

A digital bridge circuit based on the concept of independent metering control can enable the precise position control of a pneumatic cylinder, but large strokes and variable loads still cause challenges. To solve this problem, a piecewise on/off valve flow compensator and a composite friction observer were innovatively designed in this study, and they were combined with a multiple fuzzy intelligent algorithm to ensure the accuracy and robustness of pneumatic position control. Considering the starting and stopping delays and the response processes of on/off valves, a six-stage flow–duty ratio linearization relationship was proposed. Employing a parameter identification method, a static and dynamic composite friction model was presented. Then, a fuzzy PID controller was proposed, and a genetic algorithm was used to optimize the control parameters. Experiment results showed that, when focusing on a large stroke (250 mm) and varying loads (8.5–18.5 kg), for sinusoidal signal with amplitude of 150 mm and frequency of 0.125 Hz and the air supply pressure is 0.5 Mpa, the algorithm in this study could ensure that the steady-state step response error was less than 1% and the root mean squared error of the sinusoidal trajectory tracking was less than 3%.

Experimental Evaluation of the Effect of Oil Supply Pressure related to Marine Slow Speed Diesel Engine on Oil Film Pressure and Temperature Profiles within Journal Bearing

Experimental Evaluation of the Effect of Oil Supply Pressure related to Marine Slow Speed Diesel Engine on Oil Film Pressure and Temperature Profiles within Journal Bearing

Analysis of maximum radial load capacity of hydrostatic journal bearing considering supply pressure limitation by a novel method

The aim of the present study is the numerical analysis of the operating conditions (rotary speed, supply pressure) and structure parameters’ (capillary design parameter, recess wrap angle) influence on the performance of a four-rectangle recessed hydrostatic journal bearing, taking into account the limitation of the recess pressure that is always smaller than supply pressure. A new calculation method is proposed that ensures both lower time consumption than traditional numerical method (FEM, FDM) and higher accuracy than simplified method (Liang’s method). This approach examines the effect of operating conditions and structure parameters on the maximum load capacity, attitude angle, and maximum eccentricity ratio considering the supply pressure limitation. Moreover, the pressure distribution under various operating conditions and structure parameters is also investigated to explore their contributions to the performance of the hydrostatic journal bearing. The results indicate an excellent guiding significance for the design and application of hydrostatic journal bearings.

Probing asymmetric uncertain effect on symmetric three-lobe journal bearing

The conventional design process of journal bearings is completely based on deterministic theoretical predictions. The deterministic approach ignores the probabilistic and random nature of input variables and consequently, poses an arbitrary tolerance or safety factor on the performance parameters. However, such arbitrary safety factors result in performance loss when the factor is very high or failure of the system when the factor is low. This paper presents a probabilistic approach for the design of a three-lobe journal bearing considering the uncertainty in geometric parameters such as clearance, preload, and offset factor. The Monte Carlo simulation (MCS) algorithm is used for the propagation of input uncertainties to the systems’ output. To increase the efficiency of computationally expensive MCS, the moving least square (MLS) method is used as a surrogate model. The training data of the surrogate model is obtained by solving the Reynolds equation, at selective design points, using the finite difference method. To explain the probabilistic response of the bearing for various applications and different operating conditions, the results are presented for long, short, and finite bearings at three different supply pressures considering three different eccentricity ratios. The results of the probabilistic analysis show a significant deviation of the system response from its deterministically predicted values and suggest safe design values for the reliable operation of a three-lobe bearing.

Abstract 4009: Discovery of PLM-102, a highly potent 3rd generation FLT3 inhibitor, in drug-resistant FLT3-ITD-TKD mutated acute myeloid leukemia

Abstract Mutations of the FMS-like tyrosine kinase 3 (FLT3) gene occur in approximately 25 ~ 30% of all acute myeloid leukemia (AML) cases and FLT3-ITD mutations are associated with a particularly unfavorable prognosis, with an increased risk of relapse and shorter overall survival (OS) compared with AML patients without the mutation. Even though multiple FLT3 inhibitors are in various stages of clinical evaluation, resistance to FLT3 inhibitors resulting from acquired point mutations in tyrosine kinase domain (TKD) have limited the sustained efficacy of treatments. Among them, a “gatekeeper” mutation (F691L) is resistant to most available FLT3 inhibitors. Here, we show the efficacy and mechanism of PLM-102, developed an orally available and highly selective small molecule, in overcoming drug-resistant FLT3-ITD-TKD mutations as a strong candidate of the 3rd generation of FLT3 inhibitor. PLM-102 displays extraordinary potency of enzyme inhibitory activities of all FLT3 WT/mutants including F691L with IC50 values of &amp;lt;1 nM. In FLT3-ITD-positive cell lines (MV4-11, MOLM-13, MOLM-14, Ba/F3-ITD-D835Y, Ba/F3-ITD-F691L), PLM-102 shows about 18~25-fold higher anti-proliferative activities than Gilteritinib. Also, PLM-102 potently inhibited the phosphorylation of FLT3 and its downstream signaling pathways, and induced apoptosis as evidenced by PARP-cleavage and caspase-3 activation. Moreover, in AML-related xenograft mouse models (MV4-11, MOLM-14, Ba/F3-ITD-D835Y, Ba/F3-ITD-F691L), once-daily oral dose of PLM-102 significantly suppressed the tumor growth and achieved complete tumor regression. In addition, the outstanding efficacy of our compound has been confirmed in large tumor xenograft models. These results are very encouraging because large tumors have a limited blood supply and high interstitial fluid pressure, leading to a poor absorption of anticancer drugs. Pharmacokinetics of PLM-102 displayed higher bone-marrow exposure indicating better target engagement and benefits in the clinical translation in AML. In conclusion, PLM-102 is a promising therapeutic candidate for the FLT3-ITD-mutated AML as well as the acquired resistance to current FLT3 inhibitors. Citation Format: Jin-Hee Park, Jae-Seon Lee, Su-jin Oh, So-Deok Lee, Yong June Choi, Keon Wook Kang, Miran Moon, Soo Yeon Jang, Myung Jin Kim, Yong-Chul Kim. Discovery of PLM-102, a highly potent 3rd generation FLT3 inhibitor, in drug-resistant FLT3-ITD-TKD mutated acute myeloid leukemia. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4009.

An optimal configuration method for microgrid second-use battery storage system considering users allocate the cost of peak-shaving auxiliary service

The second use of retired batteries can reduce energy storage system (ESS) costs, relieve the power supply pressure of the power grid during peak hours, peak cutting and valley filling and promote energy saving and emission reduction. Power users can allocate a certain amount of peak-shaving auxiliary service costs to guide users to cut peaks and fill valleys. This paper presented an optimal configuration method for a microgrid second-use battery energy storage system (BESS) considering the users allocate peak shaving auxiliary service costs. A second-use BESS optimization configuration model was established to configure the second-use BESS with the lowest cost and the lowest peak shaving service cost allocated by users. The optimization model was solved by the particle swarm algorithm (PSO). And compared with the configured conventional BESS of residential area micro-grid. Simulation is carried out on the MATLAB platform, and the results verify the model’s and algorithm’s rationality.

A Fault Diagnosis Tool for Electrohydraulic Actuators

Abstract This letter introduces a new method for fault diagnosis of electrohydraulic actuators (EHA). Common faults include abnormal supply pressure, viscous friction, bulk modulus, and oil leakage. First, a validated model of an EHA is used to simulate faults at varying percent perturbations to generate data. The harmonics of the corresponding servo-valve control signal are calculated using sliding discrete Fourier transform (DFT) and stored. A fully connected neural network is then trained to predict fault cases using harmonic information. Simulation results show high accuracy for diagnosis of individual cases and ability to diagnose mixed cases. The actuator motion reference signal is also shown to impact overall diagnosability. Finally, the method was tested on experimental data consisting of nominal and low-pressure cases. Random disturbances were added to simulation training data to allow more robustness and resulted in 80% accuracy on the 10 experimental datapoints. It is demonstrated that a validated model can be used to diagnose faults in actual experimental setup. Future work will be done to diagnose non-pressure experimental cases.

Effect of fuel injection timing on performance and emissions with a dedicated direct injector in a hydrogen engine

In this study, hydrogen fuel was injected directly into a cylinder using a prototype of a dedicated hydrogen direct injector (HDI). The effects of fuel injection timing and amount of hydrogen fuel injected on engine output performance and emissions (e.g., nitrogen oxides and carbon dioxide) were investigated by varying the fuel injection timing from before top dead center (BTDC) 190 crank angle degree (CAD) toward BTDC 60 CAD. Strategies for maximizing the engine’s output performance when an after-treatment system for nitrogen oxide removal catalysts is not used were assessed. When using the HDI, a torque improvement result (up to 35.9%) can be obtained even under the condition that the hydrogen supply pressure was half as low as compared to the case of using a gasoline direct injector for hydrogen fuel. Under the condition of retarded fuel injection timing, a locally rich mixture is formed to increase the emission of nitrogen oxides at a level of 50 ppm or higher. The engine oil is burned to affect the emission of carbon dioxide (CO2), which is proportional to the load.

Multi-objective design optimization of hydride hydrogen storage reactor structured with finned helical tubes based on energetic and economic analyses

Hydride-based systems are a potential alternative to hydrogen storage technologies due to their simple structure and ambient operating conditions. The optimization of hydride reactor design factors is highly correlated to the targeted application. This research focuses on optimizing the thermal-static performance of LaNi5-holding helically coiled hydride reactors employing combined response surface methodology, computational modeling, and a desirability approach. The structural geometric design optimization factors include the diameter of the helical tubes and shell, the number of helical tubes, the pitch, and the distance between two adjacent helical tubes. Responses comprise a dimensionless characteristic response – weight ratio (static performance) and 90 % absorption time with maximal heat extraction rate (thermal performance). The quadratic regression model outperformed the linear regression models in terms of accuracy and reliability, effectively reducing the number of computational runs by 83 % compared to the standard parametric study-based technique. Combinatorically assessing the weight ratio and thermal power to be set to the maximum at the quickest absorption time resulted in selecting the best helical reactor design. The optimal base case was further improvised by integrating fins, which were optimized using the proposed methodology. The optimal base case and finned helical reactor subjected to sensitivity analysis revealed that the latter exhibited an average 18 % fall in complete saturation time and a 16 % rise in thermal power despite the 5.66 % loss in weight ratio. The Levelized cost of hydrogen storage was substantially reduced by 18–23 % when operated at higher supply pressures and fluid inlet temperatures. Besides, when the price of the finned reactor to its base case ratio was cut from 1.5 to 1.1, the optimized finned reactor turned economical. Furthermore, the outcomes of a systematic literature comparative study demonstrated that the constructed finned helical reactor was superior to its equivalent, accounting for a 60–75 % drop in 90 % saturation time. As an upshot, this study aids the researchers in designing accurate and apt objective-based hydride reactors using the proposed statistical method: coupled quadratic regression-thermal modeling-desirability approach-based design optimization.

Photovoltaic panel waste assessment and embodied material flows in China, 2000–2050

Solar photovoltaics (PV) is one of the most promising renewable energy sources for climate change mitigation. However, not all green energy installations may not continue to be sustainable after their service life. With the largest installed solar capacity in the world, China is expected to face significant challenges in managing the end-of-life (EoL) PV panels in the coming decades, which have not been well addressed yet.Further, the massive deployment and planning of solar energy systems in China has led to a dramatic increases in demand for raw materials, which places more pressure on the available resources. In this study, we have developed a dynamic, technology-based material flow analysis model to clarify the stock, flow and secondary supply potential of waste PV panel materials in China from 2000 to 2050. The waste generation and circular flow characteristics of the component materials in PV panels are comprehensively investigated, which set important boundary conditions for the recovery and recycling of key materials. The results show that approximately 134 million metric tons (Mt) and 72 Mt of waste PV panels will be cumulatively generated in China up to 2050 under the early loss and regular loss scenarios, respectively. Polysilicon glass accounts for the largest share of PV waste, nearly 64% by weight, followed by aluminum (16%) and steel (11%). Precious metals such as Ag, Ga, In, and Te, account for less than 1% of the total PV waste, but can provide considerable economic benefits if recycled wisely. The potential of secondary resources from PV waste may reduce the supply pressure on the natural materials to some extent, but they could not fully mitigate the material supply resks. We suggest that stakeholders in the solar energy industry should take urgent actions, including recycling technology innovations, effective collection systems and incentive measures, to address the growing challenge of waste PV panels in China.