WSEAS Transactions on
Heat and Mass Transfer
Print ISSN: 1790-5044
Volume 10, 2015
Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.
Volume 10, 2015
Title of the Paper: Performance of Stage and Direct Method of Mass Concrete Construction in Controlling Temperature Gradient
Authors: Masykur Kimsan, Morgan L. Setiady, Chandra Yudi Kusuma, Kurniati Ornam, Edi Cahyono
Abstract: Mass concrete construction always deals with the temperature control issue since the process including the heat transfer following the oxidation process and may generate thermal crack for high temperature gradient between layers as low thermal diffusivity of concrete may generate internal restraint and resulting tensile stress at some parts of the concrete, which does not perform well in resisting tension force. Quality control and assurance of mass concrete construction among projects are unique and it is significantly recommended to arrange appropriate procedure.This paper evaluates temperature development and its gradient between layers of mass concrete construction with stage and direct method. Curing method was performed by assuring that the temperature from the concrete surface to the lower level remained similar, or may vary with no more than 20oC. This curing technique performed excellent in office (stage method) and hotel (direct method) raft foundation. The trendline of those two foundations were typically similar, not to mention the time difference. Therefore, it may be expected that thermal cracking did not occur in the concrete during construction and curing phase. Moreover, should cubic polynomial interpolation is used, the behavior of temperature development shows precise result for second degree polynomials.
Keywords: mass concrete, temperature, temperature difference, thermocouple, thermal crack
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #7, pp. 61-67
Title of the Paper: Reliability of the Past Climate Reconstructions Based on the Borehole Measurements
Authors: T. I. Bukharova, O. V. Nagornov, S. A. Tyuflin
Abstract: There were many past climate reconstructions based on the borehole measurements. The measured temperature-depth profiles both in rock and glaciers present the input data for solutions of the inverse problems for determination of the boundary conditions at the surface. However, the properties of such solutions have not been derived with mathematical point of view. We find out that the solution of this problem is not unique and stable. The uniqueness and stability properties take place for the inverse problems that assume solution in the form of the finite segments of the Fourier series for the temperature. We formulate the algorithm that provides reliable temperature reconstructions.
Keywords: Boreholes, Climate reconstruction, Heat and mass transfer, Inverse problems
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #6, pp. 53-60
Title of the Paper: Analysis on Electromagnetic Heating and Spray Formation of Ethanol Fuel in Local-Contact Microwave-Heating Injector (LMI) System
Authors: Lukas Kano Mangalla, Hiroshi Enomoto, Usman Rianse, Yulius B. Pasolon
Abstract: Heating fuel system becomes an important solution for utilizing bio-ethanol fuel in internal combustion engine to improve atomization and evaporation of the spray. A novel heating system of fuel flow inside the injector using electromagnetic heating is applied in LMI system. Comprehensive study on ethanol microwave heating and it is the effect on spray performances of the LMI system was conducted numerically and experimentally. Numerical modeling was developed in COMSOL Multiphysics to simulate the heating performances of ethanol inside the heating zone where the electromagnetic heating process occurred. The important phenomena of electromagnetism, heat transfer and fluid flow were solved based on the implicit method using Backward Differentiation Formula (BDF) solver. Electromagnetic heating performances were evaluated by comparing several parameters design such as geometry, size and shape of the heating zone. Spray characteristics of fuel injected were experimentally evaluated by measuring the droplets diameter and distribution. These properties were evaluated by using a laser dispersion spray analyzer (LDSA) and high speed camera. Spray formation can be evaluated from images captured during injection. Image analysis was conducted using Images-J to investigate the effect of electromagnetic heating on the breakup of the droplets. Simulation results indicate the dependency of fuel temperature distribution on the spatial and temporal distribution of electric field inside heating area. Fuel temperature was evaluated at the tip of the injector and both simulation and experimental results were found to satisfy the agreement. An increasing of fuel temperature tends to improve the atomization and provides the small droplet dispersion during electromagnetic heating.
Keywords: LMI system, Heating performance, Microwave heating, Injector, Ethanol and Spray formation
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #5, pp. 44-52
Title of the Paper: Time Direct and Time Inverse Problems for Wave Energy and Steel Quenching Models, Solved Exactly and Approximately
Authors: Buike Margarita, Buikis Andris, Kalis Harijs
Abstract: In this paper we develop mathematical models for 3-D hyperbolic heat equation. This equation describes the mathematical models for steel quenching in highly agitated water and wave power of energy by waves of ocean surface. 1-D model is obtained from 3-D problem by conservative averaging method. We construct their exact analytical solutions by the Green function method. We solve problem with constant initial conditions in the form of triple or one series. We solve time reverse problems for the determination of the initial heat flux. Approximate solution of 1-D hyperbolic heat equation is obtained by finite difference method, including solution with exact spectrum. The conservative averaging method till now was used with polynomial approximation, but here we use hyperbolic approximation.
Keywords: Hyperbolic Equation, Ocean Energy, Green Function, Exact Solution, Inverse Problem, Finite difference, Spectral problem, Exact spectrum, Ordinary differential system, Integral spline
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #4, pp. 30-43
Title of the Paper: Feasibility of Simultaneous CO2 Storage and CH4 Production from Natural Gas Hydrate Using Mixtures of CO2 and N2
Authors: Bjorn Kvamme
Abstract: Production of natural gas from hydrate using carbon dioxide opens up for a win-win situation in which carbon dioxide can be safely stored in hydrate form while releasing natural gas from in situ hydrate. This concept has been verified experimentally and theoretically in different laboratories worldwide, and lately also through a pilot plant in Alaska. The use of carbon dioxide mixed with nitrogen has the advantage of higher gas permeability. Blocking of flow channels due to formation of new hydrate from injected gas will also be less compared to injection of pure carbon dioxide. The fastest mechanism for conversion involves the formation of a new hydrate from free pore water and the injected gas. As a consequence of the first and second laws of thermodynamics the most stable hydrate will form first in a dynamic situation, which involves that carbon dioxide will dominate the first hydrates formed from water and carbon dioxide / nitrogen mixtures. This selective formation process is further enhanced by favorable selective adsorption of carbon dioxide onto mineral surfaces as well as onto liquid water surfaces, which facilitates efficient heterogeneous hydrate nucleation. In this work we examine limitations of hydrate stability as function of gradually decreasing content of carbon dioxide. It is argued that if the flux of gas through the reservoir is high enough to prevent the gas from being depleted for carbon dioxide prior to subsequent supply of new gas, then combined carbon dioxide storage and natural gas production is still feasible. Otherwise the residual gas dominated by nitrogen will still dissociate the methane hydrate, if the released in situ CH4 from hydrate do not mix in with the gas but escape through separate flow channels by buoyancy. The ratio of nitrogen to carbon dioxide in such mixtures is therefore a sensitive balance between flow rates and rates for formation of new carbon dioxide dominated hydrate. Hydrate instability due to under saturations of hydrate formers have not been discussed in this work but might add additional instability aspects.
Keywords: Methane Hydrates, Carbon Dioxide Storage, Nitrogen, Methane Production
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #3, pp. 21-30
Title of the Paper: Effects of Radiation on Free Convection Flow past an Upward Facing Horizontal Plate in a Nanofluid in the Presence of Internal Heat Generation
Authors: M. B. K. Moorthy, T. Kannan, K. Senthilvadivu
Abstract: This article aims to present a numerical investigation for the effects of radiation on heat and mass transfer characteristics over an upward facing horizontal flat plate embedded in a porous medium filled with a nanofluid when internal heat generation is present. The Buongiornio nanofluid model is implemented wherein Brownian motion and thermophoresis effects are present. The transformation of the governing boundary layer equations into ordinary differential equations has been carried out by employing similarity transformations. The solutions of the transformed governing equations have been obtained by using MATLAB BVP solver bvp4c. The results are presented graphically and discussed for various parameters such as the buoyancy ratio Nr, Brownian motion Nb, thermophoresis Nt, radiation R and Lewis number Le in the presence of internal heat generation. Thermal radiation leads to an appreciable increase in temperature and nanoparticle volume fraction profiles. The Brownian motion and the thermophoresis of nanoparticles increases the effective thermal conductivity of the nanofluid. The slip velocity, the local heat transfer rate and mass transfer rate are significantly increased when the Lewis number and the radiation increase in the presence of internal heat generation.
Keywords: Free Convection, Porous Medium, Radiation, Nanofluid, Internal heat generation
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #2, pp. 9-20
Title of the Paper: Prediction of Behaviour of Cementitious Composites Under Fire Conditions
Authors: Jiri Vala, Anna Kucerova, Petra Rozehnalova
Abstract: Prediction of non-stationary behaviour of cementitious composites as crucial materials of concrete building structures, at high temperatures, namely under fire conditions contains still a lot of difficulties, related to i) multiphysical analysis, dealing with the coupled heat and (liquid and vapour) mass transfer and related mechanical effects, ii) open questions of existence and uniqueness of formal mathematical solutions, including the convergence of numerical algorithms, iii) design and identification of suitable material characteristics, supportable by rather inexpensive experiments: the macroscopic mass, momentum and energy conservation equations need to exploit available information from micro-structural considerations. This paper discusses common traditional and advanced computational modelling and simulation approaches and shows a possible practical compromise between the model complexity and the reasonable possibility of identification of material characteristics of all components and their changes. An illustrative example confronts computational results from such a simplified model with experimental ones, performed in the specialized laboratory at the Brno University of Technology.
Keywords: Cementitious composites, modelling of heat and mass transfer, fire simulation
WSEAS Transactions on Heat and Mass Transfer, ISSN / E-ISSN: 1790-5044 / 2224-3461, Volume 10, 2015, Art. #1, pp. 1-8