scholarly journals Bimetallic ammeter: a novel method of current measurement

2020 ◽  
Vol 4 ◽  
pp. 2
Author(s):  
Robert Frederik Uy ◽  
Qiaozi Miao ◽  
Chenghao Yuan
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Expansion ◽  
Specific Heat ◽  
Electric Current ◽  
Mechanical Displacement ◽  
Novel Method ◽  
Specific Heat Capacities ◽  
Experimental Values ◽  
Good Agreement

An electric current flowing through a bimetallic coil heats it up, and due to thermal expansion, the coil either unwinds or winds depending on the direction of net heat transfer and the specific heat capacities of the metals used. This means that by relating a certain measure of its mechanical displacement with current, the bimetallic coil can be used as an ammeter. Thus, a mathematical model relating the current to the time taken by the bimetallic coil to unwind a fixed displacement was developed and verified through experiments, which show a good agreement between theoretical and experimental values.

Heat Transfer From a Cylinder in Crossflow With Transpiration Cooling

1963 ◽  
Vol 85 (2) ◽  
pp. 173-177 ◽  
Author(s):  
B. V. Johnson ◽  
J. P. Hartnett
Keyword(s):  
Heat Transfer ◽  
Stagnation Point ◽  
Heat Transfer Performance ◽  
Separated Flow ◽  
Local Heat Transfer ◽  
Flow Region ◽  
Local Heat ◽  
Stagnation Flow ◽  
Experimental Values ◽  
Good Agreement

Local heat-transfer measurements are reported for a transpiration-cooled cylinder in crossflow. The stagnation point measurements are found to be in good agreement with results from plane stagnation flow theory. In the laminar region beyond the stagnation point, the equivalent wedge method is found to predict heat-transfer performance within 10 percent of the experimental values. In the separated flow region the experimental results demonstrate that the transpiration process is still very effective in reducing the heat transfer.

Considerations about Maximum Temperature of Toroidal Transformers in Steady-State Conditions

2020 ◽  
Vol 7 (1) ◽  
pp. 22-29
Author(s):  
Adrian Pleșca ◽  
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Ambient Temperature ◽  
Electric Current ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Maximum Difference ◽  
Novel Method ◽  
Theoretical Results

In this paper, a novel method based on a thermal mathematical model which includes the main geometrical, physical and thermal parameters of the toroidal transformer has been developed in order to obtain the maximum temperature inside the transformer during steady-state operating conditions. The influence of electric current and ambient temperature on the maximum temperature has been investigated. To validate the proposed method, some experimental tests have been done. The analyzed transformer had a rated power of 2kVA and the rated primary voltage of 230V. There is a good correlation between experimental and theoretical results with a maximum difference of 3°C.

Dropwise Evaporation

1979 ◽  
Vol 101 (3) ◽  
pp. 441-446 ◽  
Author(s):  
C. Bonacina ◽  
S. Del Giudice ◽  
G. Comini
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Specific Heat ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Technical Process ◽  
Experimental Apparatus ◽  
Mist Cooling ◽  
Transfer Mechanisms ◽  
Very High

Evaporation of atomized liquids on hot surfaces is identified as an interesting technical process, characterized by very high values of specific heat fluxes. An experimental apparatus, expressely built for the evaluation of heat transfer mechanisms in mist cooling with low excess temperatures, is described. A mathematical model, based on the assumption of dropwise evaporation, is used to correlate the experimental results.

Comparisons between Experiments and a Theoretical Model of Heat and Mass Transfer in Rotary Regenerators with Nonsorbing Matrices

1981 ◽  
Vol 103 (2) ◽  
pp. 189-195 ◽  
Author(s):  
J. G. van Leersum ◽  
C. W. Ambrose
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer ◽  
Equilibrium Model ◽  
Experimental Facility ◽  
Heat And Moisture ◽  
Good Agreement

A mathematical model of condensation, evaporation and heat transfer in a regenerator having a non sorbing matrix is derived. Good agreement between heat and moisture effectivities predicted by a simulation of the model, and corresponding results from an independently derived equilibrium model is shown for a particular case. Details of an experimental facility for testing the performance of a rotary regenerator are given, and a comparison between results obtained from the facility and those produced by the model are given.

Modeling and Dynamic Evaluation of a Two-Stage Two-Spool Servovalve Used for Pressure Control

1991 ◽  
Vol 113 (4) ◽  
pp. 709-713 ◽  
Author(s):  
S. T. Tsai ◽  
A. Akers ◽  
S. J. Lin
Keyword(s):  
Mathematical Model ◽  
Control Valve ◽  
Pressure Control ◽  
Experimental Results ◽  
Two Stage ◽  
Dynamic Evaluation ◽  
Second Stage ◽  
Experimental Values ◽  
Pressure Control Valve ◽  
Good Agreement

Experimental results for a unique design of a two-spool pressure control valve were reported by Anderson (1984). The first stage is a dynamically stable flapper-nozzle valve for which a mathematical model is already available (Lin and Akers, 1989a). For the second stage, however, which consists of two parallel spools in a common body, no such model existed. The purpose of this paper was therefore to construct such a model and to compare results calculated from it to experimental values. Moderately good agreement with experimental values was obtained.

A Mathematical Model For Steady Operation of Stirling-Type Engines

1968 ◽  
Vol 90 (1) ◽  
pp. 45-50 ◽  
Author(s):  
E. B. Qvale ◽  
J. L. Smith
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Heat Exchangers ◽  
Correction Factors ◽  
Transfer Rates ◽  
Flow Friction ◽  
Independent Variables ◽  
Basic Performance ◽  
Good Agreement

A mathematical model of Stirling-type engines has been developed. The complexity of the problem has been reduced by analyzing the various components of the engine (heat exchangers, regenerator, and cylinders) separately for cyclically steady conditions, and by selecting pressure, temperature, and mass as the independent variables. The required piston displacements are a computed result. Losses due to flow friction, piston blow-by, and finite heat transfer rates have been accounted for by applying correction factors to the basic performance which is computed without these effects. The theory has been carried out for engines, but it is equally valid for refrigerators with minor modification. The theory is in good agreement with available experimental data.

Study of the Fluid Flow in the Elliptical Duct by the Method of Characteristics

1993 ◽  
Vol 115 (1) ◽  
pp. 80-84 ◽  
Author(s):  
Yuan Mao Huang ◽  
C. H. Ho
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Method Of Characteristics ◽  
Numerical Results ◽  
Hyperbolic Type ◽  
Governing Equations ◽  
The Method Of Characteristics ◽  
The Finite Difference Method ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

This study develops a mathematical model to determine the properties of laminar flow in the elliptical duct. With some assumptions, the nonlinear governing equations of the air in the elliptical duct are transformed into the hyperbolic type. The method of characteristics is then applied. Numerical results are obtained by using the finite difference method and the uniform interval scheme. The air properties in the elliptical duct are analyzed. The local Nusselt number and the heat transfer coefficient along the duct are studied. The numerical results are compared and show good agreement with the available data.

scholarly journals A Novel Method for Determining the Curie Temperature of Ferroelectric Films

1993 ◽  
Vol 310 ◽  
Author(s):  
Chi Kong Kwok ◽  
Seshu B. Desu
Keyword(s):  
Thermal Expansion ◽  
Curie Temperature ◽  
Elastic Constants ◽  
Ferroelectric Phase ◽  
Film Stress ◽  
Ferroelectric Films ◽  
Stress Changes ◽  
Novel Method ◽  
Curie Temperatures ◽  
Good Agreement

AbstractA novel technique to measure the Curie temperature of ferroelectric thin films has been developed. The method is based on identifying changes in slope of film stress vs temperature plot. At the Curie temperature, ferroelectric films undergo a phase transition from ferroelectric phase to paraelectric phase. Due to this phase transformation, physical properties of films such as elastic constants and coefficients of thermal expansion also change at the Curie temperature. Consequently, at this temperature the temperature coefficient of film stress changes since it is related to elastic constants and thermal expansion coefficient. Thus, by measuring the film stress as a function of temperature, the Curie temperature can be determined. The Curie temperatures measured by this method are in good agreement with the literature values. Small discrepancies that were observed can be attributed to the intrinsic stresses present in the films.

scholarly journals Development of Model and Simulation of Heat Transfer Phenomena during Hydrothermal Processing Using SOLIDWORKS®

2020 ◽  
Author(s):  
Muhammad Musaddique Ali Rafique ◽  
Umair Shah
Keyword(s):  
Heat Transfer ◽  
Reactor Vessel ◽  
Hydrothermal Processing ◽  
Important Process ◽  
Model And Simulation ◽  
Composite Wall ◽  
Materials Used ◽  
Inner Vessel ◽  
Experimental Values ◽  
Good Agreement

Hydrothermal /super critical processes are important process to synthesize materials which are otherwise difficult to form under normal conditions. A mathematical model is developed using standard transport equations to calculate the time for heating of hydrothermal reactor and computer simulation of the model was carried out in SOLIDWORKS® to validate it. The materials used to form reactor vessel were stainless steel (outer body) and TEFLON (PFA) (inner vessel). It was shown that composite wall, its geometry, construction & properties greatly affect the time and pattern of heat transfer. The time calculated and pattern generated were found to be in good agreement with experimental values.

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