Bayesian models for the determination of resonant frequencies in a DI diesel engine

A time series method for the determination of combustion chamber resonant frequencies is outlined. This technique employs the use of Markov-chain Monte Carlo (MCMC) to infer parameters in a chosen model of the data. The development of the model is included and the resonant frequency is characterised as a function of time. Potential applications for cycle-by-cycle analysis are discussed and the bulk temperature of the gas and the trapped mass in the combustion chamber are evaluated as a function of time from resonant frequency information

Bubble Lift-off Size in Forced Convective Subcooled Boiling Flow

Forced convective subcooled boiling flow experiments were conducted in a BWR-scaled vertical upward annular channel. Water was used as the testing fluid, and the tests were performed at atmospheric pressure. A high-speed digital video camera was applied to capture the dynamics of the bubble nucleation process. Bubble lift-off diameters were obtained from the images for a total of 91 test conditions. A force balance analysis of a growing bubble was performed to predict the bubble lift-off size. The dimensionless form of the bubble lift-off diameter was formulated to be a function of Jacob number and Prandtl number. The proposed model agreed well with the experimental data within the averaged relative deviation of ±35.2 %

Thermal performance of dynamic, origami‐inspired geometries: An experimental study

Origami has become an increasingly popular geometry in thermal engineering, namely, heat regulatory applications such as heat sinks and radiators. In this study, the radiative heating and radiative and natural convective cooling of three origami geometries (W‐fold, Miura Ori (1), and Miura Ori (2)) made of heavy‐duty aluminum foil under a radiative heater with different powers (800, 1600, and 2400 W) and different compression lengths (0.15, 0.25, 0.35, and 0.45 m) were investigated. It was found that the Miura Ori (1) and Miura Ori (2) geometries have three to four times high temperature differences (the maximum temperature at the end of the heating process minus the initial temperature) than the W‐fold geometry. The Miura Ori (2) and Miura Ori (1) geometries produced high heat capacity enhancements of 1.2–3.2 times at high compression lengths that showed great potential for applications such as solar steam generators. The overall heat transfer coefficient for cooling can be controlled by changing the compression length of the origami geometry, allowing for dynamic surface temperature controls. This parameter decreases by up to 25.3%, 22.6%, and 45.9% for W‐fold, Miura Ori (1), and Miura Ori (2), respectively, in comparison to their flat states

A numerical approach to assess the impact of the SLM laser parameters on thermal variables

Due to extraordinarily high heating and cooling rates, understanding the selective laser melting (SLM) process remains a challenge. To evaluate the impact of processing parameters on distinct underlying surfaces, a three-dimensional finite element model is presented. To forecast the temperature distribution inside a finite solid model, a moving Gaussian heat source was created to scan the model with temperature-dependent material properties. In the finite model, the impact of processing factors such as laser power, scan rate, and scan spacing were investigated to measure thermal variables such as cooling rate, thermal gradient, and solidification rate in a layer with solid and powder bases. The maximum track temperature was observed to be increasing over the whole track length, which had a substantial influence on the thermal gradient, cooling rate, and solidification rate. The maximum track temperature, melt pool form, and thermal variables were shown to be strongly influenced by laser power and scan speed when compared to scan spacing. Furthermore, the underlying base had a substantial influence on the observed temperature values and melt pool shap

Dryer design parameters and parts specifications for an industrial scale bagasse drying system / Parámetros de diseño del secador y especificaciones de piezas para un sistema de secado de bagazo a escala industrial

The sugar industry is an ideal sector for electricity cogeneration due to a large amount of burnable bagasse produce as a by-product. Bagasse produced in the sugar industry always consists of moisture affecting the efficiency of a boiler in the cogeneration plant. In our case study, a cogeneration plant run by bagasse burning found with bagasse moisture problem and suffocating with low power generation for the last few years. The boiler efficiency per tonne of bagasse is currently lower than optimal due to the substantial percentage of water present in the bagasse. A bagasse dryer design for this industry can improve the efficiency of a boiler as well as the cogeneration plant. In this paper, a pneumatic bagasse drying system is proposed to reduce the moisture content of bagasse from 48% to 30%. This work provides a full analysis of bagasse dryer design parameters, including specifications for dryer system components, such as feeders, fan, drying tube, and cyclone. The total bagasse drying system proposed is expected to be fitted within a 6 × 6 × 25 m space to dry 60 tph of bagasse, reducing the moisture content from 48% to 30%, in full compliance with all relevant Australian and company standards

Aggregation-Induced Emission (AIE), Life and Health

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health

Experimental Study on Interfacial Area Transport in Vertical Upward Bubbly Two-Phase Flow in an Annulus

Forced convection subcooled water boiling experiments were conducted in a vertical annular channel. A high-speed digital video camera was applied to record the dynamics of the subcooled boiling process. The flow visualization results show that the bubble departure frequency generally increases as the heat flux increases. For some cases, the departure frequency may reach a limit around 1000 bubbles/second. In addition, bubble lift-off diameter, bubble growth rate and bubble velocity after bubble lift-off were determined by analyzing the images. The experimental data obtained from this study can be used in modeling the bubble departure frequency, bubble lift-off diameter, and bubble dynamics in forced convection subcooled boiling

Local Flow Measurements of Vertical Upward Bubbly Flow in an Annulus

Local measurements of flow parameters were performed for vertical upward bubbly flows in an annulus. The annulus channel consisted of an inner rod with a diameter of 19.1 mm and an outer round tube with an inner diameter of 38.1 mm, and the hydraulic equivalent diameter was 19.1 mm. Double-sensor conductivity probe was used for measuring void fraction, interfacial area concentration, and interfacial velocity, and Laser Doppler anemometer was utilized for measuring liquid velocity and turbulence intensity. A total of 20 data sets for void fraction, interfacial area concentration, and interfacial velocity were acquired consisting of five void fractions, about 0.050, 0.10, 0.15, 0.20, and 0.25, and four superficial liquid velocities, 0.272, 0.516, 1.03, and 2.08 m/s. A total of 8 data sets for liquid velocity and turbulence intensity were acquired consisting of five void fractions, about 0.050, and 0.10, and four superficial liquid velocities, 0.272, 0.516, 1.03, and 2.08 m/s. The constitutive equations for distribution parameter and drift velocity in the drift-flux model, and the semi-theoretical correlation for Sauter mean diameter namely interfacial area concentration, which were proposed previously, were validated by local flow parameters obtained in the experiment using the annulus

Photographic Study of Bubble Behaviors in Forced Convection Subcooled Boiling

Forced convection subcooled water boiling experiments were conducted in a vertical annular channel. A high-speed digital video camera was applied to record the dynamics of the subcooled boiling process. The flow visualization results show that the bubble departure frequency generally increases as the heat flux increases. For some cases, the departure frequency may reach a limit around 1000 bubbles/second. In addition, bubble lift-off diameter, bubble growth rate and bubble velocity after bubble lift-off were determined by analyzing the images. The experimental data obtained from this study can be used in modeling the bubble departure frequency, bubble lift-off diameter, and bubble dynamics in forced convection subcooled boiling

Formulation of one-dimensional interfacial area transport equation in subcooled boiling flow

In relation to the formulation of one-dimensional interfacial area transport equation in a subcooled boiling flow, the bubble-layer thickness model was introduced to avoid many covariances in crosssectional averaged interfacial area transport equation in the subcooled boiling flow. The one dimensional interfacial area transport equation in the subcooled boiling flow was formulated by partitioning a flow region into two regions; boiling two-phase (bubble-layer) region and liquid singlephase region. The bubble-layer thickness model assuming the square void peak in the bubble-layer region was developed to predict the bubble-layer thickness of the subcooled boiling flow. The obtained model was evaluated by void fraction profile measured in an internally heated annulus. It was shown that the bubble-layer thickness model could be applied to predict the bubble-layer thickness as well as the void fraction profile. In addition, the constitutive equation for the distribution parameter of the boiling flow in the internally heated annulus, which was used for formulating the bubble-layer thickness model, was developed based on the measured data. The model developed in this study will eventually be used for the development of reliable constitutive relations, which reflect the true transfer mechanisms in subcooled boiling flows