Abstract: This paper reported an experimental research of
steady-state heat transfer behaviour of a gas flowing through a fixed
bed under the different operating conditions. Studies had been carried
out in a fixed-bed packed methanol synthesis catalyst percolated by air
at appropriate flow rate. Both radial and axial direction temperature
distribution had been investigated under the different operating
conditions. The effects of operating conditions including the reactor
inlet air temperature, the heating pipe temperature and the air flow rate
on temperature distribution was investigated and the experimental
results showed that a higher inlet air temperature was conducive to
uniform temperature distribution in the fixed bed. A large temperature
drop existed at the radial direction, and the temperature drop increased
with the heating pipe temperature increasing under the experimental
conditions; the temperature profile of the vicinity of the heating pipe
was strongly affected by the heating pipe temperature. A higher air
flow rate can improve the heat transfer in the fixed bed. Based on the
thermal distribution, heat transfer models of the fixed bed could be
established, and the characteristics of the temperature distribution in
the fixed bed could be finely described, that had an important practical
significance.
Abstract: The ability to predict an accurate temperature
distribution requires the knowledge of the losses, the thermal
characteristics of the materials, and the cooling conditions, all of
which are very difficult to quantify. In this paper, the impact of the
effects of iron and copper losses are investigated separately and
their effects on the heating in various points of the stator of an
induction motor, is highlighted by using two simple tests. In addition,
the effect of a defect, such as an open circuit in a phase of the stator,
on the heating is also obtained by a no-load test.
The squirrel cage induction motor is rated at 2.2 kW; 380 V; 5.2
A; Δ connected; 50 Hz; 1420 rpm and the class of insulation F, has
been thermally tested under several load conditions. Several
thermocouples were placed in strategic points of the stator.
Abstract: In this paper, the melting of a semi-infinite body as a
result of a moving laser beam has been studied. Because the Fourier
heat transfer equation at short times and large dimensions does not
have sufficient accuracy; a non-Fourier form of heat transfer
equation has been used. Due to the fact that the beam is moving in x
direction, the temperature distribution and the melting pool shape are
not asymmetric. As a result, the problem is a transient threedimensional
problem. Therefore, thermophysical properties such as
heat conductivity coefficient, density and heat capacity are functions
of temperature and material states. The enthalpy technique, used for
the solution of phase change problems, has been used in an explicit
finite volume form for the hyperbolic heat transfer equation. This
technique has been used to calculate the transient temperature
distribution in the semi-infinite body and the growth rate of the melt
pool. In order to validate the numerical results, comparisons were
made with experimental data. Finally, the results of this paper were
compared with similar problem that has used the Fourier theory. The
comparison shows the influence of infinite speed of heat propagation
in Fourier theory on the temperature distribution and the melt pool
size.
Abstract: The work presented in this study is related to an
energy system analysis based on passive cooling system for
dwellings. It consists to solar chimney energy performances
determination versus geometrical and environmental considerations
as the size and inlet width conditions of the chimney. Adrar site
located in the southern region of Algeria is chosen for this study
according to ambient temperature and solar irradiance technical data
availability. Obtained results are related to the glazing temperature
distributions, the chimney air flow and internal wall temperatures.
The air room change per hour (ACH) parameter, the outlet air
velocity and mass air flow rate are also determined. It is shown that
the chimney width has a significant effect on energy performances
compared to its entry size. A good agreement is observed between
these results and those obtained by others from the literature.
Abstract: This paper describes a three-dimensional thermal
model of the current path included in the low voltage power circuit
breakers. The model can be used to analyse the thermal behaviour of
the current path during both steady-state and transient conditions.
The current path lengthwise temperature distribution and timecurrent
characteristic of the terminal connections of the power circuit
breaker have been obtained. The influence of the electric current and
voltage drop on main electric contact of the circuit breaker has been
investigated. To validate the three-dimensional thermal model, some
experimental tests have been done. There is a good correlation
between experimental and simulation results.
Abstract: Reliable information about tool temperature
distribution is of central importance in metal cutting. In this study,
tool-chip interface temperature was determined in cutting of ST37
steel workpiece by applying HSS as the cutting tool in dry turning.
Two different approaches were implemented for temperature
measuring: an embedded thermocouple (RTD) in to the cutting tool
and infrared (IR) camera. Comparisons are made between
experimental data and results of MSC.SuperForm and FLUENT
software.
An investigation of heat generation in cutting tool was performed
by varying cutting parameters at the stable cutting tool geometry and
results were saved in a computer; then the diagrams of tool
temperature vs. various cutting parameters were obtained. The
experimental results reveal that the main factors of the increasing
cutting temperature are cutting speed (V ), feed rate ( S ) and depth
of cut ( h ), respectively. It was also determined that simultaneously
change in cutting speed and feed rate has the maximum effect on
increasing cutting temperature.