Heat and Mass Transfer

http://link.springer.com/journal/231

List of Papers (Total 73)

Dryout-type critical heat flux in vertical upward annular flow: effects of entrainment rate, initial entrained fraction and diameter

This study aims to reveal the effects of liquid entrainment, initial entrained fraction and tube diameter on liquid film dryout in vertical upward annular flow for flow boiling. Entrainment and deposition rates of droplets were included in mass conservation equations to estimate the local liquid film mass flux in annular flow, and the critical vapor quality at dryout conditions. ...

Heat and mass transfer boundary conditions at the surface of a heated sessile droplet

This work numerically investigates how the boundary conditions of a heated sessile water droplet should be defined in order to include effects of both ambient and internal flow. Significance of water vapor, Marangoni convection, separate simulations of the external and internal flow, and influence of contact angle throughout drying is studied. The quasi-steady simulations are ...

Application of the lattice Boltzmann method for simulation of the mold filling process in the casting industry

The aim of this work is the development of the lattice Boltzmann model for simulation of the mold filling process. The authors present a simplified approach to the modeling of liquid metal-gas flows with particular emphasis on the interactions between these phases. The boundary condition for momentum transfer of the moving free surface to the gaseous phase is shown. Simultaneously, ...

The role of the dendritic growth model dimensionality in predicting the Columnar to Equiaxed Transition (CET)

The dendrite tip kinetics model accuracy relies on the reliability of the stability constant used, which is usually experimentally determined for 3D situations and applied to 2D models. The paper reports authors` attempts to cure the situation by deriving 2D dendritic tip scaling parameter for aluminium-based alloy: Al-4wt%Cu. The obtained parameter is then incorporated into the ...

Experimental investigation of the effect of air velocity on a unit cooler under frosting condition: a case study

Finned tube evaporators are used in a wide range of applications such as commercial and industrial cold/freezed storage rooms with high traffic loading under frosting conditions. In this case study, an evaporator with an integrated fan was manufactured and tested under frosting conditions by only changing the air flow rate in an ambient balanced type test laboratory compared to ...

Modelling and performance of heat pipes with long evaporator sections

This paper presents a planar cooling strategy for advanced electronic applications using heat pipe technology. The principle idea is to use an array of relatively long heat pipes, whereby heat is disposed to a long section of the pipes. The proposed design uses 1 m long heat pipes and top cooling through a fan-based heat sink. Successful heat pipe operation and experimental ...

Influence of heat conducting substrates on explosive crystallization in thin layers

Crystallization in a thin, initially amorphous layer is considered. The layer is in thermal contact with a substrate of very large dimensions. The energy equation of the layer contains source and sink terms. The source term is due to liberation of latent heat in the crystallization process, while the sink term is due to conduction of heat into the substrate. To determine the ...

Thermal conductivity of diethylene glycol based magnesium–aluminum spinel (MgAl2O4-DG) nanofluids

The paper presents the results of measurements of the thermal conductivity of \(\hbox{MgAl}_2\hbox{O}_4\)-DG nanofluids. The dependence of the thermal conductivity on concentration of nanoparticles in various temperatures from 293.15 to 338.15 K with 15 K step was examined. Experimental data was modeled with existing theoretical models describing the effects of the concentration of ...

Numerical modelling of melting and settling of an encapsulated PCM using variable viscosity

Thermal energy storage units using macro-encapsulated PCM in industrial and residential applications are contemporary due to better efficiency during charging and discharging. This article focuses on numerical modelling of the melting process in a macro-encapsulated PCM. Accounting the non-linear enthalpy–temperature relation and ramping down the velocity in solid phase is ...

Assessment of suitability of some chosen functions for describing of sorption isotherms in building materials

This paper presents results of tests and studies conducted on six common building materials, used for constructing and finishing of external walls. These included: ceramic brick, silicate brick, autoclaved aerated concrete, cement mortar, cement–lime mortar and cement mortar modified with polypropylene fibers. Each of these materials is distinguished by the other structure of ...

An application of the non-continuous Trefftz method to the determination of heat transfer coefficient for flow boiling in a minichannel

The paper presents an application of the semi-analytical method, called the non-continuous Trefftz method, to the calculation of the heat transfer coefficients. It is very effective method for solving direct and inverse problems. The results obtained by this method are consistent with the results obtained by using complicated methods: the FEM and Beck method. Sought local heat ...

Accurate measurement of unsteady state fluid temperature

In this paper, two accurate methods for determining the transient fluid temperature were presented. Measurements were conducted for boiling water since its temperature is known. At the beginning the thermometers are at the ambient temperature and next they are immediately immersed into saturated water. The measurements were carried out with two thermometers of different ...

A 2D inverse problem of predicting boiling heat transfer in a long fin

A method for the determination of local values of the heat transfer coefficient on non-isothermal surfaces was analyzed on the example of a long smooth-surfaced fin made of aluminium. On the basis of the experimental data, two cases were taken into consideration: one-dimensional model for Bi < 0.1 and two-dimensional model for thicker elements. In the case when the drop in ...

Stationary rotary force waves on the liquid–air core interface of a swirl atomizer

A one-dimensional wave equation, applicable to the waves on the surface of the air-core of a swirl atomizer is derived analytically, by analogy to the similar one-dimensional wave equation derivation for shallow-water gravity waves. In addition an analogy to the flow of water over a weir is used to produce an analytical derivation of the flow over the lip of the outlet of a swirl ...

Inverse problem for the solidification of binary alloy in the casting mould solved by using the bee optimization algorithm

In this paper the procedure for solving the inverse problem for the binary alloy solidification in the casting mould is presented. Proposed approach is based on the mathematical model suitable for describing the investigated solidification process, the lever arm model describing the macrosegregation process, the finite element method for solving the direct problem and the ...

Lean blowout limits of a gas turbine combustor operated with aviation fuel and methane

Lean blowout (LBO) limits is critical to the operational performance of combustion systems in propulsion and power generation. The swirl cup plays an important role in flame stability and has been widely used in aviation engines. Therefore, the effects of swirl cup geometry and flow dynamics on LBO limits are significant. An experiment was conducted for studying the lean blowout ...

An approximate analytic method for calculating the temperature field for a phase transition in an embankment in a permafrost region

In this study, we applied conformal mapping and irregular perturbation methods to develop an analytic method to calculate the temperature field for a phase transition in the irregular domain of an embankment in a permafrost region. We then used this method to derive an approximate formula for the unstable temperature field of the phase transition in a homogeneous embankment over an ...

The black box model of a double-tube counter-flow heat exchanger

Variable working conditions of a double-tube counter-flow heat exchanger were analysed. During operation of the heat exchanger, the parameters (temperatures and mass flow rates) of both fluids at its inlet change, which leads to a change in its performance. Heat transfer effectiveness is commonly used to assess the heat exchanger performance, defined as the ratio of the actual to ...