Dynamic Response and Control of Multipass Heat Exchangers

1960 ◽  
Vol 82 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Masami Masubuchi
Keyword(s):  
Heat Exchangers ◽  
Transfer Functions ◽  
Analog Computer ◽  
Distributed Parameter ◽  
Third Order ◽  
Exchange Processes ◽  
And Control ◽  
Complex Coefficients ◽  
Theoretical Results ◽  
Good Agreement

The transfer functions obtained by dynamic analysis of one shell pass and 2, 3, 4, ….., 2n, 2n + 1 tube-pass heat exchangers as a distributed parameter system are presented in dimensionless forms. The heat-exchange processes are found to be governed by the third-order characteristic equations with complex coefficients, and can be solved numerically using a graphical method. The numerical examples are presented to show the clear difference of frequency response for such cases when no solid capacity exists. The analog computer and the experimental results are found to be in good agreement with the theoretical results.

Design and control of a two-dimensional telerobotic system with a haptic interface

2003 ◽  
Vol 217 (3) ◽  
pp. 169-185
Author(s):  
M-G Her ◽  
M Karkoub ◽  
K-S Hsu
Keyword(s):  
Haptic Interface ◽  
Two Dimensional ◽  
Direct Drive ◽  
Closed Loop System ◽  
Human Arm ◽  
Control Scheme ◽  
Reaction Forces ◽  
And Control ◽  
Theoretical Results ◽  
Good Agreement

A model for a ‘master-slave’ two-dimensional telerobotic dynamic system with a haptic interface device is derived. The telerobotic system consists of a ‘master’ robot, which is a direct-drive robot operated by a human arm, and a ‘slave’ robot, which is an x-y type pallet located at a remote site. When the active handle of the master is moved along an arbitrary trajectory, the remote slave duplicates the motion in a constrained or unconstrained environment. The behaviour of the environment is felt by the operator through the active handle of the master. This is achieved by feeding back the disturbance and reaction forces from the environment and the loads to the active handle. Consequently, the operator gets a feel of the task being performed without being physically at the location of the task. A control scheme is devised for the telerobotic system to establish smooth communication between the master and slave robots. This control scheme integrates the dynamics of the human arm, actuators and the environment in the closed-loop system. It was shown that the experimental and the theoretical results are in good agreement and that the design controller is robust to constrained/unconstrained environments.

On the Dynamics of Steam Liquid Heat Exchangers

1961 ◽  
Vol 83 (2) ◽  
pp. 244-251 ◽  
Author(s):  
Arvid Hempel
Keyword(s):  
Frequency Response ◽  
Heat Exchangers ◽  
Transfer Functions ◽  
Liquid Velocity ◽  
Amplitude Ratio ◽  
Analog Computer ◽  
Phase Lag ◽  
Liquid Temperature ◽  
Response Measurement ◽  
Liquid Heat

The aim of the present work has been to present relatively simple transfer functions for steam/liquid heat exchangers, relating outlet liquid temperature to variations in, respectively, the steam temperature, the liquid velocity, and the inlet liquid temperature. The transfer functions are first obtained from the partial differential equations of the system and then simplified. From the simplified expressions the transient response can readily be obtained and, in addition, they are of a form easily simulated on an analog computer. Experimental frequency response data are provided. An analog computer proved useful in analyzing phase lag and amplitude ratio in the frequency response measurement.

scholarly journals Effects of Polaron and Quantum Confinement on the Nonlinear Optical Properties in a GaAs/Ga1-xAlxAs Quantum Well Wire

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
L. Caroline Sugirtham ◽  
A. John Peter ◽  
Chang Woo Lee
Keyword(s):  
Quantum Well ◽  
Quantum Confinement ◽  
Photoionization Cross Section ◽  
Third Order ◽  
Third Harmonic ◽  
Quantum Well Wire ◽  
Geometrical Effect ◽  
Theoretical Results ◽  
Order Susceptibility ◽  
Good Agreement

The binding energy of a polaron confined in a GaAs/Ga1-xAlxAs quantum well wire is calculated within the framework of the variational technique and Lee-Low Pines approach. The polaron-induced photoionization cross section as a function of normalized photon energy for a on-centre donor impurity in the quantum wire is investigated. The oscillator strength with the geometrical effect is studied taking into account the polaron effects in a GaAs/Ga0.8Al0.2As quantum well wire. The effect of polaron on the third-order susceptibility of third harmonic generation is studied. Our theoretical results are shown to be in good agreement with previous investigations.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

Studies of local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) crystals

2021 ◽  
Vol 76 (4) ◽  
pp. 299-304
Author(s):  
Fu Chen ◽  
Jian-Rong Yang ◽  
Zi-Fa Zhou
Keyword(s):  
Crystal Field ◽  
Elongation Ratio ◽  
Paramagnetic Resonance ◽  
Local Structures ◽  
Epr Parameters ◽  
Structure Constants ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic ◽  
Theoretical Results ◽  
Good Agreement

Abstract The electron paramagnetic resonance (EPR) parameters (g factor g i , and hyperfine structure constants A i , with i = x, y, z) and local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) are theoretically investigated using the high order perturbation formulas of these EPR parameters for a 3d 9 ion under orthorhombically elongated octahedra. In the calculations, contribution to these EPR parameters due to the admixture of d-orbitals in the ground state wave function of the Cu2+ ion are taken into account based on the cluster approach, and the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the studied EPR parameters with the local structures of the Cu2+ centers. Based on the calculations, the Cu–H2O bonds are found to suffer the axial elongation ratio δ of about 3 and 2.9% along the z-axis, meanwhile, the planar bond lengths may experience variation ratio τ (≈3.8 and 1%) along x- and y-axis for Cu2+ center in (NH4)2Zn(SO4)2·6H2O and Rb2Zn(SO4)2·6H2O, respectively. The theoretical results show good agreement with the observed values.

On the Flow Fields of Inertial Impactors

1974 ◽  
Vol 96 (4) ◽  
pp. 394-400 ◽  
Author(s):  
V. A. Marple ◽  
B. Y. H. Liu ◽  
K. T. Whitby
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Relaxation Method ◽  
Water Model ◽  
Navier Stokes ◽  
Visualization Technique ◽  
Navier Stokes Equations ◽  
Theoretical Results ◽  
Plate Distance ◽  
Good Agreement

The flow field in an inertial impactor was studied experimentally with a water model by means of a flow visualization technique. The influence of such parameters as Reynolds number and jet-to-plate distance on the flow field was determined. The Navier-Stokes equations describing the laminar flow field in the impactor were solved numerically by means of a finite difference relaxation method. The theoretical results were found to be in good agreement with the empirical observations made with the water model.

scholarly journals Characterization and Control of the Microbial Community Affiliated with Copper or Aluminum Heat Exchangers of HVAC Systems

2012 ◽  
Vol 65 (2) ◽  
pp. 141-149 ◽  
Author(s):  
Michael G. Schmidt ◽  
Hubert H. Attaway ◽  
Silva Terzieva ◽  
Anna Marshall ◽  
Lisa L. Steed ◽  
...  
Keyword(s):  
Microbial Community ◽  
Heat Exchangers ◽  
Hvac Systems ◽  
And Control

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

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