We have calculated the thermal boundary resistance at the GaN/SiC, GaN/sapphire and GaN/AlN interfaces in the diffuse mismatch approximation. The obtained values were then used to examine the effect of the thermal boundary resistance on heat diffusion in AlGaN/GaN heterostructure field-effect transistors. The results show that the thermal boundary resistance at the device layer interfaces can strongly influence the temperature rise in the device channel.

532.546Temperature fields in the shaft of an operating well are studied experimentally in a quasi-stationary approximation. The expressions for radial distributions of temperature and coefficients of heat transfer are obtained with account for the dependence of the velocity of liquid flow on the radial coordinate. Calculations are made for laminar and turbulent flows.Study of temperature fields in liquid and gas flows in pipes is of importance for pipeline transportation of heat carriers and products. However, their investigation in shafts of oil wells is of particular significance. On the one hand, calculations of temperature fields in wells are important for prediction of paraffin deposits of the well walls; on the other hand, this problem is a basic one in thermal coring, which is widely used in practice in studying wells and beds.Nonstationary temperature fields in the shaft of the well and the surrounding medium mutually affect each other. The equalities of temperatures and heat fluxes on pipe walls (boundary conditions of the fourth kind) are natural boundary conditions that determine this interaction. Since solution of conjugate problems presents fundamental difficulties, the problem in a precise formulation was replaced by a simpler one. The first approach was developed by V. G. Shukhov and A. Yu. Namiot [1], who suggested using the Newton formula for heat transfer on a surface and took the coefficient of heat exchange between the flow in the well and the surrounding rocks as time-independent. E ′ . B. Chekalyuk used an integral method to take into account heat exchange between the flow and the surrounding rocks and specified heat flux in the form of convolution [2]; it is this approach within the framework of which A. N. Salamatin made his studies [3]. Other researchers [4-6] also referred to the problem under discussion, but all of them considered the problem only for a mean temperature in the well shaft. At the same time, use of thermal studies in the practice of development of oil-gas deposits aggravated the problem of calculation of radial temperature dependences in the well. This is related to the fact that a thermometer, which was run into the well on a cable along the shaft of the well and more often close to its wall, in some cases moves away from the latter, thus approaching the well axis. Therefore, it is essential to know radial temperature distributions in the flow in order to predict the thus-arising temperature anomalies. However, the study of radial temperature distributions in liquid or gas flows in the well shaft is of independent importance for development of new methods of coring based on measurements of the dependence of temperature on the distance to the well axis. However, at present there is no acceptable theory of temperature effects under these conditions.In this paper, we made an attempt to construct a theory of thermal processes in a well on the basis of a quasi-stationary approximation that lies in the fact that the differential equations for temperature are taken to be statio...

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Results are given of theoretical investigation of temperature fields arising under conditions of vibratory motion of liquid in porous media in view of compressibility. Analytical dependences of temperature on space coordinates, time, and other parameters under these conditions are constructed. Space-time dependences of temperature fields in application to oil beds are calculated, and the results of their analysis are given.

UDC 532.546An asymptotic solution of the problem of a temperature field in carbonate-containing oil-gas beds exposed to the action of an acid is obtained. Expressions for the concentration fields of the acid and reaction products and the porosity and temperature in the zero and first approximation have been constructed. The space-time distributions of the temperature have been calculated, and the contribution of various physical processes has been analyzed.Under natural conditions, the skeleton of porous oil-gas beds often contains carbonate rocks. In order to increase the efficiency of production of oil or gas under such conditions, acid treatment is employed, which consists of a chemically active reagent being injected into a porous bed, which is surrounded by impermeable cap and base rocks ( Fig. 1). As a result of partial corrosion of the bed skeleton, its porosity and permeability are increased. A lesser amount of specific energy is then required for oil extraction from the bed treated. The chemical reagent often used for this purpose is hydrochloric acid, which reacts with limestone (CaCO 3 + 2HCl = CaCl 2 + H 2 CO 3 + Q). The heat of reaction Q goes for heating up the porous medium. Measurement of the magnitude of the temperature effect with the aid of thermometers sunk into a bore-hole makes it possible to control the process of acid treatment.However, despite the wide application, the temperature fields that develop in the process of interaction of the acid with the carbonate skeleton have been inadequately studied. In this work, based on asymptotic methods, a solution was obtained for the problem of the temperature fields that develop in oil-gas beds after instantaneous injection of acid into them, when a relatively small fraction of the acid reacts for the time of injection. This regime is optimum for increasing the depth of treatment, and for this purpose special reagents that slow down the reaction rate are added into a solution [1]. In conformity with what has been said above, it is assumed for simplicity in the problem considered below that the time of acid injection into the bed is much shorter than the time of the chemical reaction in it.Description of the Problem. We will consider a temperature problem in a cylindrical coordinate system, where the medium is represented by three regions with plane interfaces (z d = h) that are perpendicular to the z d axis (Fig. 1). The first and second regions are impermeable, and the middle region of thickness 2h is porous. A reagent is injected into the region −h < z d < h from a bore-hole of radius r 0 , the axis of which coincides with the z d axis. In describing the temperature problem the following assumptions were made: the porous carbonate bed is assumed to be homogeneous and anisotropic as concerns its hydrodynamic and thermophysical properties; the temperatures of the liquid and skeleton of the porous medium at each point coincide; the natural thermal field of the Earth is considered stationary (the bed is at a depth of 1-2 km; therefore, diurnal and s...