Estimation Of Temperature Rise Research Articles

Molar heat capacity at constant volume for air from 67 to 300 K at pressures to 35 MPa

Measurements of the molar heat capacity at constant volumeCv for air were conducted with an adiabatic calorimeter. Temperatures ranged from 67 to 300 K, and pressures ranged up to 35 MPa. Measurements were conducted at 17 densities which ranged from gas to highly compressed liquid states. In total, 227Cv values were obtained. The air sample was prepared gravimetrically from research purity gases resulting in a mole fraction composition of 0.78112 N2 + 0.20966 O2 + 0.00922 Ar. The primary sources of uncertainty are the estimated temperature rise and the estimated quantity of substance in the calorimeter. Overall, the uncertainty (± 2σ) of theCv values is estimated to be less than ± 2% for the gas and ±0.5% for the liquid.

筒状アトリウムの空間温度上昇及び給気開口部風速の簡易予測手法に関する研究

Temperature rise and ventilation rate caused by a fire in a tall and narrow atrium are successfully estimated by a new model considering physical factors of atrium(floor area, height, opening arrangements), dimensionless heat release rate and Froude number. These two dimensionless numbers are estimated based on inlet-opening width, heat loss to walls, atrium aspect ratio H^2/A and inlet-to-outlet opening ratio. Laboratory measurements of temperature and ascending velocity in flame plume and atrium space, and velocity of flow induced at openings were carried out using a reduced-scale model(1/10) 1.8m×1.8m×7.2m(H) and a gas burner placed at the center of the model generating 1.5kW to 24kW as the arrangements of inlet openings were changed. The laboratory tests validated the figures produced by the model as did the results of previous experiments carried out at various scales and with various opening arrangements and heat release rates under natural and forced ventilation Comparison of the estimated temperature rise and ventilation rate using the model with the results of experiments indicates that the model can be used for estimating these values as a simple tool to evaluate the fire safety design of a tall and narrow atrium.

Temperature Rise of Foil Strain Gages on Plastics

In stain measurements of plastics using foil strain gages, the temperature rise caused by power dissipated in the gage produces serious errors. A simple model for estimating the temperature rise is proposed, that is, a single strip representing a grid is bounded onto a half space made of plastic, and generates constant heat flux. A formula and diagram, by which the maximum value of the temperature rise can be estimated, are presented in this paper. The estimated temperature rise, Tmax, is about 2 times as large as the measured one for actual gages bounded onto acrylic plates. The difference between both values is due to the incompleteness of the gage model and errors in the temperature measurement using a thermocouple. In spite of this incompleteness, the value of Tmax can still be used to estimate the temperature rise of the actual gages. This value is more useful than the power density which is often used as a parameter for estimating the temperature rise.

Temperature Field Due to a Moving Heat Source: A Moving Mesh Finite Element Analysis

The transient temperature field (as seen by a moving observer) due to a moving heat source, such as the process zone near a dynamically propagating crack tip or an external agent as in the case of welding, is analyzed by a moving-mesh finite element procedure. The effects of the temperature-dependent material properties, and of the loss of heat to the surrounding medium through convection and radiation, are studied. Situations under which conditions in the process zone may be labeled as “isothermal” or “adiabatic” are explored. Estimates of temperature rise near the tip of a crack propagating at realistic speeds in structural steels are made.

Calculations of temperature rise produced in body tissue by a spherical electrode.

Two estimates of temperature rise produced in body tissue when a spherical electrode passes current have been calculated. The estimates bracket the expected temperature rise. Time-transient and steady-state results have been obtained. The effects of heat transfer through the highly conductive metal electrode and irreversible Faradaic reactions have been considered. The calculations indicate that electrodes smaller than about 2 micron in radius produce a peak temperature rise of about 1 degree C when driven by typical square current pulses of 25 microA intensity and 200 microseconds duration. The results are presented in a graphic form allowing for quick estimation of the expected peak temperature rise around electrodes of a specific radius, which are driven with a pulse of known current density and duration.

Automation of an alternating field microelectrophoresis apparatus

The automation of a microelectrophoresis apparatus is described. It relies on digital techniques for the electric field generation, the conductance measurement, the cuvette positioning, and the temperature rise estimation deduced from the conductance. A current source is used with programmable shape, frequency, duty cycle, and duration. All the measurement steps are successively controlled by the microprocessor. As described herein, the particles motion is recorded with a camera. The apparatus is built from independent (software and hardware) modules and other detecting devices could easily be adapted.

Adiabatic heating at a dislocation pile-up avalanche

Most model calculations of the adiabatic heating which can be produced by plastic deformation give only small increases in the bulk temperature of a material. This occurs because a very significant averaging and presumed continuity of the plastic flow processes are built into the description of what otherwise is undoubtedly an extremely localized and sudden action of energy conversion on the microstructural scale. For the opposite case description, an appreciable localized heating is estimated to occur within a material if a dislocation pile-up is catastrophically released in an avalanche configuration from a collapsed obstacle. The estimated temperature rise at such a hot spot is found at the limiting dislocation velocity to be directly proportional to the Hall-Petch stress intensity factor for the strength of the internal obstacle originally impeding the growth of a slip band (or twin or crack). Thus, this description of adiabatic heating has been shown to be a particularly important effect for materials which exhibit sudden load drops in their deformation responses and for materials which are susceptible to the onset of brittle fracturing. Although this work gives emphasis to metallic materials, the same considerations are relevant for other types of crystalline solids as well, such as explosive molecular crystals and inorganic crystalline oxidizer ingredients incorporated in propellant formulations.

Monitoring the global climatic impact of direct heat addition associated with escalating energy use

Using Budyko's overall heat-balance equation, we estimate that direct heat addition associated with worldwide energy use in the year 2050 will be responsible for a mean global temperature rise of 0.27 °C at a 20 kw t per capita energy consumption for a world population of ten billion people. The corresponding temperature rise between 15 and 60 °N is estimated to be 0.44 °C. If per capita energy consumption during the year 2050 is reduced to 5 kw, (i.e. about one half of U.S. consumption in the year 1970), the estimated temperature rise for the 15–60 °N latitudinal belt will be about 0.11 °C and therefore still not negligibly small. A program for monitoring the global climatic impact of escalating energy use involves precise monitoring of the following quantities: 1. (a) the solar constant 2. (b) the effective earth-atmosphere albedo 3. (c) the net (long-wavelength) radiant energy emitted from the earth-atmosphere system. Both the effective albedo and the (long-wavelength) radiant energy emitted from the earth-atmosphere system will depend on the nature and size of particulate concentrations in the atmosphere, on molecular emitters (especially CO 2 and H 2O), cloud cover, and on the radiative-convective circulation pattern. A satellite observation program that is closely integrated with ground-based and atmospheric measurements and with a detailed program of theoretical analysis will be needed for more precise predictions of inadvertent climate changes and for developing the means to effect desirable global climate controls.

Thermal analysis of preswitching characteristics of a thin-film amorphous-chalcogenide switch

The preswitching nonohmic behaviour of amorphous-semiconductor switches could result from either Joule heating or space-charge-limited currents. After the ‘forming’ of a virgin device, electron-microscope examinations have revealed a channel whose composition differs significantly from the matrix. Also, the I/V characteristics of the blocking states of virgin and formed devices are significantly different. The preswitching I/V characteristics of a Ge15Te81S4 chalcogenide-glass switch at 300 K have been explained by Joule heating in the formed channel, with an estimated temperature rise of 25 degC above ambient at the centre of a monostable switch.

Estimation of temperature rise in electron beam heating of thin films : Tung-Po Lin, IBM J., September (1967), p. 527

Estimation of temperature rise in electron beam heating of thin films : Tung-Po Lin, IBM J., September (1967), p. 527

Clinical thermometers and urinometers: determination of their accuracy.

The purpose of this study is to determine the accuracy of some of our present-day clinical instruments, on which the physician relies for important information concerning his patients' status and progress. The study has been limited to the thermometers and urinometers in use at a 500-bed general hospital. The success of modern medicine does not depend on the absolute accuracy of these instruments either for correct diagnoses or for proper management of the patient. The healing art was far along when the physician estimated temperature rise by the laying on of hands. The urinologists of former years could roughly discern whether a person's urine was too concentrated or too dilute. Today, however, we have at our fingertips numerous instruments of precision that have rightfully taken the place of guesswork in medicine. Many times a physician comes into the modern hospital and sees on his patients' charts incongruous temperature graphs, weight

Estimating Temperature Rise in Electronic Equipment Cases

In the design of airborne electronic equipment of minimum size and weight, the ambient temperature rating of components is often limiting. This ambient temperature is the equilibrium temperature inside the case, and may determine either the choice of components or the need for external cooling means. Calculation of equilibrium temperature requires knowledge of the power dissipated in the case and the rate of heat transfer to the surroundings by conduction, convection, and radiation. To avoid often laborious calculation, a series of charts are presented as an aid to estimating temperature rise. Graphical corrections for pressure altitude are given, together with a discussion of the effects of case color, high-speed aircraft skin temprerature, and other variables.

Temperature Rise and Losses in Solid Structural Steel Exposed to the Magnetic Fields from A-C. Conductors

Experimental investigations were made for the determination of the temperature rise and the losses occurring in structural steel members exposed to the fields from a-c. conductors. The worlz originated fromn the demand among the designing engineers of an electrical manufacturing company for practical data which would enable them to estimate, at least roughly, the temperature rise and the heat losses in the more common cases of structural steel members passing near the conductors. In the paper presented here are given the results of the investigations in question. Examples are given illustrating the method of procedure in estimating temperature rise and losses in structural steel. The method of calculation applied is, in most cases, empirical. The major factors affecting temperature rise and losses are discussed on the basis of the test data. An understanding of these factors will often permit a designer to avoid iron heating without sacrifice of space or of economy. Thus a good part of the data presented apply to cases for which the temperature rise of the steel would ordinarily be considered not seriously objectionable. Iron members passing between going and return conductors in adjacent-phase layouts may reach very high temperatures; on the other hand, iron members passing at right angles to, but outside of, a group of going and return conductors will usually heat less than an iron member crossing a single conductor, when the current and minimum spacings are the same.