A nonstationary method for measuring heat fluxes

A nonstationary method for measuring heat fluxes using a hollow cylindrical probe placed in the critical cross section of a nozzle is proposed. The temperature at a fixed distance from the inner surface of the probe is measured as a function of time. The time variation of the heat flux is determined by solving the one-dimensional nonlinear heat-conduction equation.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 29, No. 1, pp. 51–55, July, 1975.     

Improved difference approximations to the heat equation

A method for obtaining difference equations from differential equations which has previously been applied to ordinary differential equations is here applied to the time-dependent heat conduction equation as a representative example of parabolic partial differential equations. Explicit difference equations are derived which are stable for all values of αΔt/Δ² and are also accurate. Implicit-algorithms with improved accuracy are also derived. Problems in cartesian and cylindrical co-ordinates are treated.     

Central difference approximations to the heat transport equation

This paper analyses the oscillatory nature of central difference approximations to the heat transport equation when convection is the important mechanism of heat transport. The effects of three different boundary conditions, various heat source profiles, the Peclet Number and the parity of the number of meshes on the amplitudes of these oscillations are described. A boundary condition is presented which suppresses the oscillations to insignificant amplitudes in the one?dimensional situation.     

Measurement of nonstationary heat fluxes by “auxiliary wall” sensors

Computational dependences are obtained to determine the nonstationary heat flux by using sensors executing the method of an auxiliary wall. The dependences are valid for an arbitrary relationship between the thermophysical properties of the sensor and the object on which it is located.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 1, pp. 99–103, July, 1979.     

On the analytical solution of a nonstationary kinetic equation for a point heat source

A nonstationary kinetic equation for a point heat source in a gas is analytically solved. The dependence of the temperature and concentration of gas molecules on the distance from the source is considered. The results are compared to experimental data on the spreading of acoustic oscillations.     

Special features of measurement of nonstationary heat fluxes by heat meters implementing the auxiliary wall method

The feasibility of measuring nonstationary heat fluxes with normal heat meters is analyzed. Calculation correlations are given for determining the variable flux from the measured drop in temperature through the thickness of the heat meter.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 5, pp. 772–778, May, 1977.     

Stable conservative difference schemes for the quasilinear parabolic heat-conduction equation

An efficient algorithm is developed for solving the quasilinear heat-conduction equation using asymmetric difference schemes satisfying the discrete analog of the conservation law.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 2, pp. 308–314, August, 1985.     

Solution of a two-dimensional equation of nonstationary heat conduction for orthotropic cylindrically bounded media

Analytical relationships are presented to determine two-dimensional (2-D) nonstationary thermal fields in a bounded orthotropic cylinder for various boundary conditions. The solution obtained generalizes a wide class of eighty boundary-value problems of nonstationary heat conduction in studies of heat exchange in the bodies being considered.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 6, pp. 1014–1021, June, 1989.     

Question of measuring nonstationary thermal fluxes

A method is proposed for measuring time-varying thermal fluxes.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 1, pp. 56–60, July, 1989.     

A class of integral transformations for the generalized equation of nonstationary heat conduction

Integral transformations for finding analytical solutions of the boundary-value problems of nonstationary heat conduction for the generalized equation of transfer in an infinite region bounded on the inside by a plane, cylindrical, or spherical surface have been constructed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 123–130, January–February, 2008.     

Application of a differential-difference method to the solution of one-dimensional nonstationary heat conduction problems with a moving boundary

A differential-difference method is applied to obtain an approximate solution of one-dimensional nonstationary heat conduction problems with a moving boundary in rectangular and cylindrical systems of coordinates. Recursion formulas are obtained for the determination of successive values of the unknown functions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 4, pp. 719–724, October, 1969.     

Application of a variational method for the solution of nonstationary heat conduction problems

We present an application of a variational principle due to Ainola, compatible with Kantorovich's method, for the solution of the first and second boundary value problems.     

Application of a differential-difference method to the solution of a one-dimensional nonstationary two-layer heat conduction problem with a moving boundary

We apply a differential-difference method to obtain an approximate solution of a nonstationary heat conduction problem with a moving boundary for a medium consisting of an unbounded plate (0xl) and a halfspace (l, 相似文献   

Use of an electronic computer to determine the heat flux by means of the nonstationary temperature field at the nozzle wall

A method to determine the heat flux in a nozzle at stream temperatures above the nozzle wall melting point is elucidated. An experimental distribution of the local heat flux along the nozzle contour is presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 29, No. 1, pp. 56–59, July, 1975.     

Electrical simulation of nonstationary heat transfer in a disperse system

The system of differential equations of heat conduction of a dispersed medium is replaced by the system of differential equations of an electrical circuit; the simulation conditions are examined.     

大温差空气源热泵在供暖系统中的应用

为了解决空气源热泵在供暖系统存在的末端匹配性差、系统运行费用高等问题,提出一种适应大温差高效热能输配的热泵系统。通过理论分析和试验验证,对大温差空气源热泵在供暖工程中的应用进行研究,比较大、小温差下的热泵系统的节能效果和供暖效果。研究结果表明:按照GB/T 25127.1—2020测算,采用大温差空气源热泵的制热系统全年制热季节性能系数HSPF可提升57%以上,循环水泵耗电量占比下降73%以上,室内温度变化偏差为±0.2℃,可以推广应用。     

Deterioration of electrodes subjected to concentrated heat fluxes in a pulse discharge

The problem of the nonstationary thermal deterioration of a metal with the motion of the phase boundaries (melting and evaporation) taken into account is solved. The results of a computation are compared with experimental data.     

Propagation and emission of a nonstationary heat wave in air

Numerical simulation of the dynamics of propagation and formation of the front of a nonstationary spherical heat wave in air is performed. The time dependence of the radiation of the front in the optical range of the spectrum is obtained. The existence of two phases in the propagation of a heat wave is established.Academic Scientific Complex A. V. Luikov Heat and Mass Transfer Institute of the Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 5, pp. 539–546, May, 1994.     

Spline identification of heat fluxes

A method is discussed for the determination of one-dimensional transient heat fluxes from the experimentally measured temperature using a spline approximation of the heat flux with subsequent application of the procedures of parametric identification.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 6, pp.1085–1089, December, 1977.     

Features of nonstationary periodic contact heat transfer

Results are presented of investigations of nonstationary periodic contact heat transfer performed on special experimental installations and under full-scale tests. The regularity of thermal hysteresis is here disclosed experimentally.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 60, No. 1, pp. 151–161, January, 1991.