scholarly journals Thermal Modelling of External Gear Machines and Experimental Validation

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2920 ◽  
Author(s):  
Rituraj Rituraj ◽  
Andrea Vacca ◽  
Mario Antonio Morselli
Keyword(s):  
Thermal Model ◽  
Experimental Validation ◽  
Volumetric Efficiency ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Power Losses ◽  
Internal Flows ◽  
Lumped Parameter ◽  
Fluid Properties ◽  
The Common

The flow of energy within external gear machines (EGMs) leads to the variation of fluid temperature in the EGMs, which affects their performance. However, the common approaches for the simulation of EGMs assume isothermal conditions. This isothermal assumption negatively impacts their modelling accuracy in terms of the internal flows which are dependent on the fluid temperature (via fluid properties). This paper presents a lumped parameter based thermal model of EGMs where the fluid temperature in the EGM is evaluated considering the effects of compression/expansion, internal flows, and power losses. Further, numerical techniques are developed to model each of these three aspects. The thermal model is validated via the outlet temperature and volumetric efficiency measurements obtained from experiments conducted on six units of an EGM taken as a reference with different internal clearances. The results from the model show that the fluid temperature increases as it is carried from the inlet side to the outlet side during the pumping operation. However, the fluid at the ends of the shafts has the highest temperature. By comparing the isothermal simulation results with the proposed thermal model, the results also point out how the isothermal assumption becomes inaccurate, particularly in conditions of low volumetric efficiency.

A New Transient Thermal Model for Predicting Cooling Temperature and Cooldown Time of a Subsea Pipe-in-Pipe Flowline System Transporting Waxy Hydrocarbons

2021 ◽  
Author(s):  
Keshawa Shukla
Keyword(s):  
Analytical Model ◽  
Production System ◽  
Thermal Model ◽  
Hydrate Formation ◽  
Pipe Production ◽  
Fluid Temperature ◽  
Waxy Crude Oil ◽  
Cooling Temperature ◽  
Fluid Properties ◽  
Transient Thermal

Abstract The proper understanding of cooling temperature and cooldown time for the operation of a subsea system producing hydrocarbons from the reservoir to the host facility is one of the important flow assurance issues for managing heat retention in the production system due to solids formation and their deposition. In this paper, an analytical transient thermal model is developed for determining the cooling temperature and cooldown time for shut-in operations of a subsea pipe-in-pipe production system, transporting waxy crude oil from the reservoir to the host facility. Here, the cooldown time is defined as the time when the fluid temperature approaches the wax appearance temperature before reaching the hydrate formation temperature during any shut-in operations. The analytical model builds upon an inhomogeneous transient method incorporating an internal temperature gradient. The model results are benchmarked against the commercial OLGA simulation results for a few selected deepwater pipe-in-pipe flowline configuration. The model predictions resemble well with OLGA results over a range of conditions. The analytical model could optimize dry insulation and cooldown time requirements efficiently for the assumed PIP flowline configurations and fluid properties under any subsea environments.

Meaningful and Physically Consistent Efficiency Definition for Positive Displacement Pumps - Continuation of the Critical Review of ISO 4391 and ISO 4409

2021 ◽  
Author(s):  
Christian Schänzle ◽  
Peter F. Pelz
Keyword(s):  
Critical Review ◽  
Volumetric Efficiency ◽  
Dead Volume ◽  
Specific Enthalpy ◽  
Positive Displacement ◽  
Displacement Pump ◽  
Fluid Properties ◽  
The Common ◽  
Isentropic Efficiency ◽  
The Ideal

Abstract ISO 4391:1984 gives the common efficiency definition for positive displacement machines. ISO 4409:2019 uses this efficiency definition to specify the procedure for efficiency measurements. If the machine conditions do not correspond with an incompressible flow due to operation at high pressure levels, the compressibility of the fluid and the dead volume of a pump must be taken into account. On this point, ISO 4391:1984 is physically inconsistent. Achten et. al. address this issue in their paper at FPMC 2019 presenting a critical review of ISO 4409:2007. They introduce new definitions of the overall efficiency as well as the mechanical-hydraulic efficiency. At the same time, they question the validity of the volumetric efficiency definition. Li and Barkei continue on this issue in their paper at FPMC 2020 and give a new efficiency definition based on the introduction of a new quantity Φ which describes the volume specific enthalpy of the conveyed fluid. The motivation of this paper is to contribute to the ongoing and fruitful discussion. Our approach starts with the most general efficiency definition, namely the isentropic efficiency. Subsequently, we make assumptions concerning the fluid properties with respect to the compressibility of the conveyed fluid. On the basis of the ideal cycle of a positive displacement pump and the p-v diagram, we derive physically consistent and more meaningful representations of the overall, the mechanical-hydraulic and the volumetric efficiency that address the inconsistency of ISO 4391:1984. Furthermore, we compare our findings with the existing results of Achten et. al. and Li and Barkei.

A Lumped Parameter Thermal Model for Single-Sided AFPM Machines With Experimental Validation

2020 ◽  
Vol 6 (3) ◽  
pp. 1065-1083
Author(s):  
Richard Burke ◽  
Artur Giedymin ◽  
Zhongze Wu ◽  
Hawwooi Chuan ◽  
Nick Bourne ◽  
...  
Keyword(s):  
Thermal Model ◽  
Experimental Validation ◽  
Lumped Parameter

On Correlating Experimental Pressure Flow and Heat Transfer Measurements From Silicon Microchannels With Theoretical Calculations

2007 ◽  
Author(s):  
Cormac Eason ◽  
Niall O’Keeffe ◽  
Ryan Enright ◽  
Tara Dalton
Keyword(s):  
Heat Transfer ◽  
Confidence Interval ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Channel Height ◽  
Outlet Temperature ◽  
Fluid Temperature ◽  
Pressure Flow ◽  
Flow And Heat Transfer ◽  
Fluid Properties

The bulk pressure flow and heat transfer characteristics of rectangular and trapezoidal microchannels etched in silicon were measured in the laminar regime. The channel hydraulic diameters were 305 μm for the Deep Reactive Ion Etched (DRIE) etched channel and 317 μm for the wet etched channel and there were 22 channels in each sample. The fluid used was purified degassed water. The inlet and outlet temperature and pressure of the fluid and the wall temperatures of the channels were measured at the inlet and outlet of the channels. Theoretical and experimental results were calculated using fluid properties at the mean fluid temperature for each data point. These were then collapsed to a single curve at constant temperature by multiplying the measured value by the ratio of the relevant fluid properties at the experimental and required temperatures. The cross section of each channel on each channel sample was measured along with the channel height and width to give an area ratio between the actual channel width and the width calculated assuming the channel was perfectly rectangular or trapezoidal. This ratio is used to compensate the theoretical results and improve their correlation with the experiment. The uncertainty in the experimental results was calculated by running the result processing calculations three times, once at nominal values and then shifting input values to their upper and lower limits based on a 95% confidence interval on the standard deviation for each inputted measurement. Theoretical calculations were run for each experimental mass flow rate in order to produce equivalent theoretical points to the experimental values. Uncertainty in the theory is also determined by running the theoretical calculations at upper, lower and nominal 95% confidence interval values for the channels being tested. It was found that while the pressure flow data from the channels matched theoretical trends and that the results for the rectangular DRIE channels showed no experimentally significant deviation from theory, the experimental data from the wet etched trapezoidal channels was lower than predictions. The heat transfer from the channels is strongly affected by the heat transferred to the coolant by the manifolds. When this effect is removed, the experimental Reynolds number Nusselt number plot becomes strongly linear. This does not agree with theoretical predictions.

A lumped-parameter electro-thermal model for cylindrical batteries

2014 ◽  
Vol 257 ◽  
pp. 1-11 ◽  
Author(s):  
Xinfan Lin ◽  
Hector E. Perez ◽  
Shankar Mohan ◽  
Jason B. Siegel ◽  
Anna G. Stefanopoulou ◽  
...  
Keyword(s):  
Thermal Model ◽  
Lumped Parameter

Lumped Parameter Modeling of a Magnetorheological Fluid Clutch

2006 ◽  
Author(s):  
John C. Ulicny ◽  
Daniel J. Klingenberg ◽  
Anthony L. Smith ◽  
Zongxuan Sun
Keyword(s):  
Mathematical Model ◽  
Physical Properties ◽  
Magnetorheological Fluid ◽  
Input Current ◽  
Fluid Composition ◽  
Fluid Temperature ◽  
Temperature Range ◽  
Lumped Parameter ◽  
Lumped Parameter Modeling ◽  
Fan Speed

A lumped-parameter mathematical model of an automotive magnetorheological (MR) fluid fan clutch was developed. This model is able to describe the average fluid temperature, average clutch temperature, and output fan speed as a function of time, input current, and fluid composition. The model also reproduces numerous features of fan operation observed experimentally and revealed a mechanism for some observed cases of hysteresis. However, it fails to capture certain other features which lead us to conclude that phenomena which are not included in the model, e.g., sedimentation and re-suspension, are important to the clutch behavior. In addition, the results indicate that certain physical properties need to be measured over a larger temperature range in order for the model to better predict the clutch behavior.

scholarly journals Measurements and Computations of Internal Temperatures of the IGBT and the Diode Situated in the Common Case

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 210
Author(s):  
Paweł Górecki ◽  
Krzysztof Górecki
Keyword(s):  
Thermal Properties ◽  
Measurement Error ◽  
Thermal Model ◽  
Bipolar Transistor ◽  
Internal Temperature ◽  
Self Heating ◽  
Factors Influencing ◽  
Proposed Model ◽  
The Common ◽  
Transient Thermal

This article proposes effective methods of measurements and computations of internal temperature of the dies of the Insulted Gate Bipolar Transistor (IGBT) and the diode mounted in the common case. The nonlinear compact thermal model of the considered device is proposed. This model takes into account both self-heating phenomena in both dies and mutual thermal couplings between them. In the proposed model, the influence of the device internal temperature on self and transfer thermal resistances is taken into account. Methods of measurements of each self and transfer transient thermal impedances occurring in this model are described and factors influencing the measurement error of these methods are analysed. Some results illustrating thermal properties of the investigated devices including the IGBT and the antiparallel diode in the common case are shown and discussed. Computations illustrating the usefulness of the proposed compact thermal model are presented and compared to the results of measurements. It is proved that differences between internal temperature of both dies included in the TO-247 case can exceed even 15 K.

Definition and Experimental Validation of a Second-Order Thermal Model for Electrical Machines

2021 ◽  
pp. 1-1
Author(s):  
Eric Armando ◽  
Aldo Boglietti ◽  
Fabio Mandrile ◽  
Enrico Carpaneto ◽  
Sandro Rubino ◽  
...  
Keyword(s):  
Thermal Model ◽  
Experimental Validation ◽  
Second Order ◽  
Electrical Machines
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