Vacuum sensing based on the influence of gas pressure on thermal time constant

2014 ◽  
Author(s):  
D. V. Randjelovic ◽  
A. G. Kozlov ◽  
O. M. Jaksic
Keyword(s):  
Time Constant ◽  
Gas Pressure ◽  
Thermal Time ◽  
Thermal Time Constant

An Experimental Thermal Time-Constant Correlation for Hydraulic Accumulators

1990 ◽  
Vol 112 (1) ◽  
pp. 116-121 ◽  
Author(s):  
A. Pourmovahed ◽  
D. R. Otis
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Time Constant ◽  
Gas Pressure ◽  
Thermal Time ◽  
Temperature History ◽  
Nitrogen Gas ◽  
Real Gas ◽  
Transfer Data ◽  
Thermal Time Constant

A thermal time-constant correlation based on experimental data is presented for gas-charged hydraulic accumulators. This correlation, along with the thermal timeconstant model, permits accurate prediction of accumulator thermodynamic losses and the gas pressure and temperature history during compression or expansion. The gas is treated as a real gas, and all properties are allowed to vary with both pressure and temperature. The correlation was developed from heat transfer data obtained with a 2.5 liter piston-type accumulator charged with nitrogen gas. Both horizontal and vertical orientations were studied. The experiments covered the range, 2.6×108<Ra*<9.5×1010, 0.77<L/D<1.50, and 0.71<T*<1.0. The gas pressure was varied between 1.0 and 19.5 MPa.

A test method of thermal time constant for uncooled infrared focal plane array

2019 ◽  
Vol 48 (12) ◽  
pp. 1204003
Author(s):  
刘子骥 Liu Ziji ◽  
赵晟晨 Zhao Shengchen ◽  
赵征庭 Zhao Zhengting ◽  
李聿达 Li Yuda ◽  
郑 兴 Zheng Xing ◽  
...  
Keyword(s):  
Time Constant ◽  
Focal Plane ◽  
Focal Plane Array ◽  
Test Method ◽  
Thermal Time ◽  
Infrared Focal Plane Array ◽  
Thermal Time Constant

Fast and rigorous use of thermal time constant to characterize back end of the line test structure in advanced technology

2008 ◽  
Vol 48 (8-9) ◽  
pp. 1279-1284
Author(s):  
A. Reverdy ◽  
P. Perdu ◽  
H. Murray ◽  
M. de la Bardonnie ◽  
P. Poirier
Keyword(s):  
Time Constant ◽  
Test Structure ◽  
Advanced Technology ◽  
Thermal Time ◽  
Thermal Time Constant ◽  
Line Test

An Algorithm for Computing Nonflow Gas Processes in Gas Springs and Hydropneumatic Accumulators

1985 ◽  
Vol 107 (1) ◽  
pp. 93-96 ◽  
Author(s):  
D. R. Otis ◽  
A. Pourmovahed
Keyword(s):  
Equation Of State ◽  
Heat Transport ◽  
Time Constant ◽  
Thermal Time ◽  
Experimental Measurements ◽  
Expansion Process ◽  
Thermal Time Constant ◽  
Property Data

An algorithm for computing nonflow gas processes is based on the Benedict-Webb-Rubin equation of state and a thermal time constant to describe heat transport. Specific results are presented for an accumulator charged with nitrogen operating in the range 60 to 150 atmospheres and 200 to 330°K. The computer results compare favorably with NBS nitrogen property data and with experimental measurements for an expansion process and a sinusoidal cycle.

Parallel analysis of thermal field in a layered DC cable

2014 ◽  
Vol 24 (3) ◽  
pp. 613-626
Author(s):  
Jerzy Golebiowski ◽  
Robert Piotr Bycul
Keyword(s):  
Steady State ◽  
Field Distribution ◽  
Time Constant ◽  
Thermal Field ◽  
Thermal Time ◽  
Content Type ◽  
The Core ◽  
Thermal Time Constant ◽  
Steady State Current

Purpose – The purpose of this paper is to prepare procedures for determination of characteristics and parameters of DC cables on the basis of transient and steady thermal field distribution in their cross-sections. Design/methodology/approach – Steady-state current rating was computed iteratively, with the use of steady thermal field distribution in the cable. The iterative process was regulated with respect to this field by changes of the mean surface temperature of the sheath of the cable. It was also controlled with respect to the unknown current rating by deviations of the temperature of the core from the maximum sustained temperature of the insulation (material zone) adjacent to the core. Heating curves were determined (in arbitrarily selected points of the cross-section of the cable) by a parallel algorithm described thoroughly in the first part of the paper. The algorithm was used for computing of transient thermal field distribution throughout the whole cross-section. Thermal time constant distributions were determined by the trapezium rule, where the upper integration limit of respective thermal field distributions was being changed. Findings – Using the methods prepared the following characteristics/parameters of the cable were determined: steady-state current rating, spatial-time heating curves, mean thermal time constant distribution. The results were verified and turned to be in conformance with those of the IEC 287 Standard and a commercial software – Nisa v. 16. Speedup and efficiency of the parallel computations were calculated. It was concluded that the parallel computations took less time than the sequential ones. Research limitations/implications – The specialized algorithms and software are dedicated to cylindrical DC cables. Practical implications – The knowledge of the determined characteristics and parameters contributes to optimal exploitation of a DC cable during its use. Originality/value – The algorithms of determination of the steady-state current rating and thermal time constant are original. The software described in the appendix has also been made by the authors.

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