Transient Heat Conduction

Filling of an empty cryogenic vessel initially at atmospheric temperature with a cryogenic liquid at its saturation temperature will initiate a high temperature difference between the terminals of the annular space containing the thermal insulating material. This high temperature difference is behind the dependence of thermal properties of the thermal insulation material on its temperature. Based on the authors’ own research and classroom experience, this book contains two parts, in Part (I): the 1D cylindrical coordinates, non-linear partial differential equation of transient heat conduction through a temperature dependent thermal conductivity of a thermal insulation material is solved analytically using Kirchhoff’s transformation. In Part (II): the 2D body-fitted coordinates, non-linear partial differential equation of transient heat conduction through a temperature dependent thermal properties of a thermal insulation material that is subjected to a natural convection heat transfer boundary condition associated with a periodic change in ambient temperature and heat flux of solar radiation is simulated numerically using the fully implicit Finite Volume Method

The sudden filling of an empty cryogenic liquid storage tank initially at atmospheric temperature with a cryogenic liquid at its saturation temperature will initiate a sudden high temperature difference between the terminals of the annular space containing the thermal insulating material. This high temperature difference is behind the dependence of thermal conductivity of the thermal insulation material on its temperature. In addition, it will initiate a potential for the evaporation of cryogenic liquid due to the transient heat transfer inside the cryogenic liquid storage tank. This energy loss is of a great economic interest especially when the size of cryogenic liquid storage tank is relatively big. Based on the authors’ own research and classroom experience, this book contains a text for researchers and for a graduate level coarse. The analytical solution of the non-linear partial differential equation in spherical & cylindrical coordinates of transient heat conduction through a thermal insulation material of a thermal conductivity temperature dependent is solved analytically using Kirchhoff’s transformation.

This work deals with the development of new theoretical and experimental techniques for the efficient estimation of thermophysical properties and source-term in micro and macro-scale. Two kinds of source term were studied: a constant and a time varying source term. The time wise variation of the source term had a sinusoidal and a
pulse form. Two devices were used for the sample heating: An electrical resistance and a laser diode. For the data acquisition, an infrared camera was used, providing a full cartography of properties of the medium and also non-contact temperature measurements. The direct problem was solved by the finite differences method, and two approaches were used for the solution of the inverse problem, depending on the time varying behavior of the source term. Both approaches deal with the parameters
estimation within the Bayesian framework, using the Markov Chain Monte Carlo (MCMC) method via the Metropolis Hastings (MH) algorithm for the constant source term, and the Kalman filter for the time-varying source term. The nodal strategy is presented as a method to deal with the large number of experimental data problems.
Experiments were carried out in a sample with well known thermophysical properties, determined by classical methods.

In heat exchanger, the enthalpy is transferred between two or more fluids, at different temperatures. The major challenge in designing a heat exchanger is to make the equipment more compact and achieve a high heat transfer rate using minimum pumping power. In recent years, the high cost of energy and material has resulted in an increased effort aimed at producing more efficient heat exchange equipment. Furthermore, as a heat exchanger becomes older, the resistance to heat transfer increases owing to fouling or scaling. The heat transfer rate can be improved by introducing a disturbance in the fluid flow thereby breaking the viscous and thermal boundary layer. However, in the process pumping power may increase significantly and ultimately the pumping cost becomes high. Therefore, to achieve a desired heat transfer rate in an existing heat exchanger at an economic pumping power, several techniques have been proposed in recent years and are discussed under the classification section. In this work, a study of transient heat transfer in double tube heat exchanger has enhanced. The inner tube of the setup was made with corrugation on both inner and outer walls by twisting the pipe from one end, which gives the more swirling motion to the fluid particles flowing over it. The flow inside the pipe was considered as turbulent, and the analysis was done experimentally and theoretically by using the ANSYS workbench. The experimental results were compared with the experimental values taken in the setup done by considering the inner tube as normal pipe. In both heat exchangers the values were taken and compared with the theoretical analysis. Temperature distribution and heat transfer rate were calculated and the details of the study have been discussed in this paper.

The flash method, proposed by Parker, Butler, Jenkins and Abbott from the U.S. Navy Radiological Defense Laboratory in 1961, is the most popular method for measuring the thermal diffusivity of solids. In this method, the front surface of a small sample is subjected to a very short burst of radiant thermal energy. The resulting temperature rise on the opposite surface of the sample is measured and the thermal diffusivity is computed from the temperature rise versus time data. Also, the specific heat can be computed from the measured data, thus allowing
for the calculation of the thermal conductivity. Several theoretical models are available for the flash method, which include adiabatic boundary conditions, heat losses, surface coating effects, among other aspects. In this paper, tests were made for the identification of thermo-physical properties of a Ceramic block. The Netzsch Nanoflash LFA
447/1 of LTTC/COPPE/UFRJ was used for the measurements.

Note: This Paper is converted to a text Book

The sudden filling of an empty cryogenic liquid storage tank initially at atmospheric temperature with a cryogenic liquid at its saturation temperature will initiate a sudden high temperature difference between the terminals of the annular space containing the thermal insulating material. This high temperature difference is behind the dependence of thermal conductivity of the thermal insulation material on its temperature. In addition, it will initiate a potential for the evaporation of cryogenic liquid due to the transient heat transfer inside the cryogenic liquid storage tank. This energy loss is of a great economic interest especially when the size of cryogenic liquid storage tank is relatively big. Based on the authors’ own research and classroom experience, this book contains a text for researchers and for a graduate level coarse. The analytical solution of the non-linear partial differential equation in spherical & cylindrical coordinates of transient heat conduction through a thermal insulation material of a thermal conductivity temperature dependent is solved analytically using Kirchhoff’s transformation.

Note: This Paper is converted to a text Book

The sudden filling of an empty cryogenic liquid storage tank initially at atmospheric temperature with a cryogenic liquid at its saturation temperature will initiate a sudden high temperature difference between the terminals of the annular space containing the thermal insulating material. This high temperature difference is behind the dependence of thermal conductivity of the thermal insulation material on its temperature. In addition, it will initiate a potential for the evaporation of cryogenic liquid due to the transient heat transfer inside the cryogenic liquid storage tank. This energy loss is of a great economic interest especially when the size of cryogenic liquid storage tank is relatively big. Based on the authors’ own research and classroom experience, this book contains a text for researchers and for a graduate level coarse. The analytical solution of the non-linear partial differential equation in spherical & cylindrical coordinates of transient heat conduction through a thermal insulation material of a thermal conductivity temperature dependent is solved analytically using Kirchhoff’s transformation.