scholarly journals Numerical Simulation and Experimental Study on Temperature Distribution of Self-Lubricating Packing Rings in Reciprocating Compressors

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Jia Xiaohan ◽  
Zhang Qingqing ◽  
Feng Jianmei ◽  
Peng Xueyuan
Keyword(s):  
Temperature Distribution ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Radial Temperature ◽  
Operational Conditions ◽  
External Cooling ◽  
Packing Rings ◽  
Compressor Reliability

The nonuniform abrasion failure and high-temperature thermal failure of packing rings have a significant influence on compressor reliability, particularly that of oil-free compressors. In this study, a test rig was constructed to measure the dynamic temperature of packing rings under different operational conditions in an oil-free reciprocating compressor. The dynamic axial and radial temperature distributions of the packing rings were obtained using an innovative internal temperature testing device that kept the thermocouples and packing box relatively static during compressor operation. A three-dimensional heat transfer model was also developed to analyze the temperature distribution of the packing boxes, piston rod, and cylinder during such operation. Good agreement was observed between the simulation results and experimental data, which showed an average relative error of less than 2.35%. The results indicate that the pressure ratio exerts a significant effect on the axial temperature distribution and determines which packing ring reaches the maximum temperature. They also show the average temperature to rise with an increase in the rotational speed and to fall with an improvement in the external cooling conditions. Finally, the material of the packing rings was found to affect the temperature gradient from their inner to outer surface.

Electromagnetic performance and thermal analysis of a novel permanent magnet fluxed-switching coupler

2021 ◽  
pp. 1-18
Author(s):  
Lezhi Ye ◽  
Yulong Zhang ◽  
Mingguang Cao
Keyword(s):  
Temperature Distribution ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Three Dimensional ◽  
Load Condition ◽  
Maximum Load ◽  
Maximum Temperature ◽  
The Novel ◽  
Transient Field ◽  
Three Dimensional Finite Element

To solve the problem of complex operating device and permanent magnets (PMs) demagnetization at high temperature, a new type of permanent magnet fluxed-switching coupler (PMC) with synchronous rotating adjuster is proposed. Its torque can be adjusted by rotating a switched flux angle between the adjuster and PMs along the circumferential direction. The structural feature and working principle of the PMC are introduced. The analytical model of the novel PMC was established. The torque curves are calculated in transient field by using the three-dimensional finite element method (3-D FEM). The temperature distribution of the novel PMC under rated condition is calculated by 3-D FEM, and the temperature distribution of the PM is compared with that of the conventional PMC. The simulation and test results show that the maximum temperature of copper disc and PM of the novel PMC are 100 °C and 48 °C respectively. The novel PMC can work stably for a long time under the maximum load condition.

Cooling of Concentrator Photovoltaic Cells Using Mini-Scale Jet Impingement Heat Sinks

2018 ◽  
Author(s):  
Ali Radwan ◽  
Meshack Hawi ◽  
Mahmoud Ahmed
Keyword(s):  
Heat Transfer ◽  
Flow Model ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Cell Temperature ◽  
Maximum Cell ◽  
T System

In this study, an efficient cooling technique for concentrator photovoltaic (CPV) cells is proposed to enhance the system electrical efficiency and extend its lifetime. To do this, a comprehensive three-dimensional conjugate heat transfer model of CPV cells layers coupled with the heat transfer and fluid flow model inside jet impingement heat sink is developed. Four different jet impingement designs are compared. The investigated designs are (A) central inlet jet, (B) Hypotenuse inlet jet, (C) staggered inlet jet, and (D) conventional jet impingement design with side drainage. The effect of coolant flowrate on the CPV/T system performance is investigated. The model is numerically simulated and validated using the available experiments. The performance of CPV system is investigated at solar concentration ratios of 20 and coolant flowrate up to 6000g/min. It is found that increasing the flowrate from 60 g/min to 600 g/min decrease the maximum cell temperature by 31°C for the configuration D while increasing the flowrate from 600 g/min to 6000 g/min reduce the cell temperature by 20.2°C. It is also concluded that at a higher flowrate of 6000g/min, all the investigated configurations relatively achieve better temperature uniformity with maximum temperature differences of 0.9 °C, 2.1 °C, 3.6 °C, and 3.9 °C for configurations A, B, C, and D respectively.

First Steps Towards the Development of a 3D Nuclear Fuel Behavior Solver With OpenFOAM

2018 ◽  
Author(s):  
Alessandro Scolaro ◽  
Ivor Clifford ◽  
Carlo Fiorina ◽  
Andreas Pautz
Keyword(s):  
Nuclear Fuel ◽  
Material Properties ◽  
Three Dimensional ◽  
Small Strain ◽  
Theoretical Background ◽  
Transfer Model ◽  
Temperature Dependent ◽  
Reactor Physics ◽  
Radial Temperature ◽  
Fuel Behavior

A new 3D fuel behavior solver is currently under collaborative development at the Laboratory for Reactor Physics and Systems Behaviour of the École Polytechnique Fédérale de Lausanne and at the Paul Scherrer Institut. The long term objective is to enable a more accurate simulation of inherently 3D safety-relevant phenomena which affect the performance of the nuclear fuel. The current implementation is a coupled three-dimensional heat conduction and linear elastic small strain solver, which models the effects of burnup- and temperature dependent material properties, swelling, relocation and gap conductance. The near future developments will include the introduction of a smeared pellet cracking model and of material inleasticities, such as creep and plasticity. After an overview of the theoretical background, equations and models behind the solver, this work focuses on the recent preliminary verification and validation efforts. The radial temperature and stress profiles predicted by the solver for the case of an infinitely long rod are compared against their analytical solution, allowing the verification of the thermo-mechanics equations and of the gap heat transfer model. Then, an axisymmetric model is created for 4 rods belonging to the Halden assembly IFA-432. These models are used to predict the fuel centerline temperature during power ramps recorded at the beginning of life, when the fuel rod performance is still not affected by more complex high burnup effects. Finally, the predictions are compared with the experimental measurements coming from the IFPE database. This first preliminary results allow a careful validation of the temperature-dependent material properties and of the gap conductance models.

scholarly journals Cooled Pads for Tilting-Pad Journal Bearings

Lubricants ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 92
Author(s):  
Steven Chatterton ◽  
Paolo Pennacchi ◽  
Andrea Vania ◽  
Phuoc Vinh Dang
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Journal Bearings ◽  
Maximum Temperature ◽  
Inlet Temperature ◽  
Oil Film ◽  
External Cooling ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings (TPJBs) are widely installed in rotating machines owing to their high stability, but some drawbacks can be noted, such as higher cost with respect to cylindrical journal bearings and thermal issues. High temperatures in the pads correspond to low oil-film thicknesses and large thermal deformations in the pads. Therefore, the restriction of the maximum temperature of the bearing is a key aspect for oil-film bearings. The temperature reduction is generally obtained by adopting higher oil inlet flowrates or suitable oil nozzles. In this paper, the idea of using cooled pads with internal channels in which an external cooling fluid is circulated will be applied to a TPJB for the first time. The three-dimensional TEHD model of the TPJB, equipped with a cooled pad, will be introduced, and the results of the numerical simulations will be discussed. Several analyses have been performed in order to investigate the influence of cooling conditions, such as the type, flowrate, inlet temperature and number of cooled pads. Two types of pad geometry with different cross-sections of the cooling circuit, namely, circular and six-square multi-channel sections, have been compared to the reference bearing with solid pads. Simple experimental tests were performed by means of a test rig equipped with a cooled pad bearing obtained with the additive manufacturing process, thus showing the effectiveness of the solution and the agreement with the predictions.

Computational analysis of temperature distribution in microwave-heated potatoes

2020 ◽  
Vol 26 (6) ◽  
pp. 465-474
Author(s):  
Deepak Singh ◽  
Dhananjay Singh ◽  
Sattar Husain
Keyword(s):  
Mathematical Model ◽  
Temperature Distribution ◽  
Computational Analysis ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Maximum Temperature ◽  
Bacterial Inactivation ◽  
Food Material ◽  
Drying Time ◽  
Temperature Ranges

This research article reports the computational analysis of temperature distribution in microwave-heated convenience food such as potato. The detailed study of temperature (because temperature is a function of bacterial inactivation) and microwave powers along with drying time for the preservation of food material has been presented. Therefore, a mathematical model for potato sample is developed to predict the behavior of temperature distribution at each possible point and different shapes (slab, cylindrical, and spherical) of food material. The developed mathematical model is programmed by MATLAB software. Another parameter, microwave power is also a function of temperature. The ranging values of various microwave powers (125 W, 375 W, 625 W, 875 W, and 1250 W) along with different values of drying time (0 to 10 minutes) have been used for computation. The obtained results show the uniformity of temperature distribution throughout the whole product in the form of a three-dimensional structure. The model provides the minimum and maximum temperature ranges in specimens without performing an experiment which depicts the condition of bacterial inactivation.

Transient Thermal Response of a Rotating Cylindrical Silicon Nitride Workpiece Subjected to a Translating Laser Heat Source, Part II: Parametric Effects and Assessment of a Simplified Model

1998 ◽  
Vol 120 (4) ◽  
pp. 907-915 ◽  
Author(s):  
J. C. Rozzi ◽  
F. P. Incropera ◽  
Y. C. Shin
Keyword(s):  
Temperature Distribution ◽  
Convection Heat Transfer ◽  
Surface Region ◽  
Ambient Air ◽  
Laser Source ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
Beam Diameter ◽  
Radial Temperature ◽  
Near Surface

In a companion paper (Rozzi et al., 1998), experimental validation was provided for a transient three-dimensional numerical model of the process by which a rotating workpiece is heated with a translating laser beam. In this paper, the model is used to elucidate the effect of operating parameters on thermal conditions within the workpiece and to assess the applicability of an approximate analysis which is better suited for on-line process control. From detailed numerical simulations, it was determined that the thickness of a surface thermal layer decreases with increasing workpiece rotational speed and that the influence of axial conduction on the workpiece temperature distribution increases with decreasing laser translational velocity. Temperatures increase throughout the workpiece with increasing laser power, while the influence of increasing beam diameter is confined to decreasing near-surface temperatures. Temperature-dependent thermophysical properties and forced convection heat transfer to the laser gas assist jet were found to significantly influence the maximum temperature beneath the laser spot, while radiation exchange with the surroundings and mixed convection to the ambient air were negligible. The approximate model yielded relations for calculating the radial temperature distribution within an r-φ plane corresponding to the center of the laser source, and predictions were in reasonable agreement with results of the numerical simulation, particularly in a near-surface region corresponding to the depth of cut expected for laser-assisted machining.

Fabrication of a Cell Culture Plate With a Three-Dimensional Printed Mold and Thermal Analysis of PDMS-Based Casting Process

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Myo Min Zaw ◽  
William D. Hedrich ◽  
Timothy Munuhe ◽  
Mohamad Hossein Banazadeh ◽  
Hongbing Wang ◽  
...  
Keyword(s):  
Cell Culture ◽  
Temperature Distribution ◽  
Fused Deposition Modeling ◽  
Thermal Damage ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Curing Temperature ◽  
Maximum Temperature ◽  
Maximum Temperature Difference ◽  
Fused Deposition

Abstract Polydimethylsiloxane (PDMS)-based casting method was used to fabricate PDMS cell culture platforms with molds printed by a fused deposition modeling (FDM) printer. Cell viability study indicated that the produced plates have the suitable biocompatibility, surface properties, and transparency for cell culture purposes. The molds printed from acrylonitrile-butadiene-syrene (ABS) were reusable after curing at 65 °C, but were damaged at 75 °C. To understand thermal damage to the mold at elevated temperatures, the temperature distribution in an ABS mold during the curing process was predicted using a model that considers conduction, convection, and radiation in the oven. The simulated temperature distribution was consistent with the observed mold deformation. As the maximum temperature difference in the mold did not change appreciably with the curing temperature, we consider that the thermal damage is due to the porous structure that increases the thermal expansion coefficient of the printed material. Our study demonstrated that FDM, an affordable and accessible three-dimensional (3D) printer, has great potential for rapid prototyping of custom-designed cell culture devices for biomedical research.

scholarly journals Investigation on Smoke Flow in Stairwells induced by an Adjacent Compartment Fire in High Rise Buildings

2019 ◽  
Vol 9 (7) ◽  
pp. 1431 ◽  
Author(s):  
Jun Zhang ◽  
Jingwen Weng ◽  
Tiannian Zhou ◽  
Dongxu Ouyang ◽  
Qinpei Chen ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Three Dimensional ◽  
Factor H ◽  
Maximum Temperature ◽  
Vertical Temperature ◽  
Location Factor ◽  
Index Model ◽  
Smoke Flow ◽  
Vertical Temperature Distribution ◽  
Fire Location

The aim of this study was to evaluate the transport phenomena of smoke flow and vertical temperature distribution in a 21-story stairwell with multiple fire locations and openings. A large eddy simulation (LES) method was used to model the smoke flow in a stairwell model with a set of simulation parameters, wherein the fire heat release rate (HRR) and fire location were varied. Based on the results, a wall attachment effect was found in three-dimensional figures. Moreover, with an increase in the fire HRR, the effects were more pronounced. The simulation results verified that the vertical temperature distribution is an index model with a natural logarithm, where the pre-finger factor and attenuation coefficient increase considerably in accordance with an increase in the fire HRR. Moreover, there was a decrease in the maximum temperature (Tm) with an increase in the fire location factor (h*) due to the upward thermal smoke. Moreover, heat mainly accumulates in the area above a fire source. However, h* has a slight influence on the time required to reach Tm within the range of 53–64 s. Furthermore, the direction of the airflow at each side opening in the stairwell varied in accordance with the variation in the fire location changes, and a regular calculation was carried out.

Accurate Predetermination of the Process Parameters for Glass/Glass Laser Bonding Based on the Temperature Distribution Analysis

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yanyi Xiao ◽  
Wen Wang ◽  
Jianhua Zhang
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Thermal Imager ◽  
Distribution Analysis ◽  
Analysis Model ◽  
Glass Laser ◽  
Element Analysis ◽  
Laser Bonding

Temperature distribution is the key factor affecting the bonding quality in the glass/glass laser bonding process. In this work, the finite element method was used to establish three-dimensional (3D) numerical analysis model of the temperature field during bonding. Based on the result of the finite element analysis, the crucial parameters and their influences on the temperature distribution were discussed. In order to predetermine the necessary process parameter values for bonding, a nonlinear multiparameter fitting formula was established to predict the maximum temperature. The fitting model was validated experimentally by recording the maximum temperature during laser bonding via an infrared thermal imager.

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