WSEAS Transactions on Heat and Mass Transfer
Print ISSN: 1790-5044
E-ISSN: 2224-3461
Volume 7, 2012
Issue 1, Volume 7, January 2012
Title of the Paper: The Bioactive Material Transfer from Herbs
Authors: Jelenka B. Savković-Stevanović, Ruzica D. Berić, Jelena J. Djurović
Abstract: The bioactive substance transfer from the medical herbs in the solid- liquid system was investigated. The investigation was performed by experiments in laboratory and pilot plant conditions. The experiments were carried out with Oenothere biennis L. and Betula pendula Roth L. at the atmospheric pressure. The specific substance transfer rate and diffusion coefficients were determined. The overall mass transfer coefficients in the liquid phase were defined involving convention, inner diffusion and bounded layer diffusion. The component mass transfer coefficients were examined.
Keywords: Extraction, medical herbs, transfer rate, component mass transfer coefficient, transport criteria
Title of the Paper: Mesoscale Numerical Method for Prediction of Thermal Fluid Flow through Porous Media
Authors: Nor Azwadi Che Sidik, Mohd Irwan Mohd Azmi
Abstract: In this paper, the lattice Boltzmann method, a mesoscale numerical tool based on particle distribution function is used to simulate thermal fluid flow in porous media. The key point is to combine the simplest four and nine lattice velocity model to represent the temperature and density distribution functions respectively. Wide range of Rayleigh numbers and material's porosity has been applied to study their effects on the thermal fluid flow in the enclosure. Our numerical experiments demonstrate excellent agreements when the computed results are compared with those predicted by the finite element solution to the Brinkmann- Forccheimer equation and the conventional lattice Boltzmann scheme. This indicates the applicability of the present approach in realistic simulation of thermal fluid flow in porous media.
Keywords: Lattice Boltzmann, Double population, Natural convection, Porous media
Title of the Paper: Wireless Non-Floating Type Thermal Bubble Accelerometer with Semi-Cylindrical Chamber
Authors: Jium-Ming Lin, Po-Kuang Chang
Abstract: This research proposes a wireless RFID-based thermal bubble accelerometer design, and relates more particularly for the technology to manufacture and package it on a flexible substrate. The key technology is to integrate both a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for fabrication and usage. In this paper the heaters as well as the thermal sensors are directly adhering on the surface of the flexible substrate without the traditional floating structure. Thus the structure is much simpler and cheaper for manufacturing, and much more reliable in large acceleration impact condition. In addition, the shape of the chamber is changed as a semi-cylindrical or semispherical one instead of the conventional rectangular type. Comparisons are also made; one can see the sensitivity of the proposed new shape design is better.
Keywords: Wireless RFID Tag, Thermal Bubble Accelerometer, Flexible Substrate, Thermal Sensor, Heater, E-beam Evaporation, Thermal Piles, Polysilicon Doped with P-type Impurity
Issue 2, Volume 7, April 2012
Title of the Paper: Opacity Analysis and Estimation of CO2 Exhausted by a Diesel Engine Vehicle Running under Urban Traffic Conditions
Authors: Negoitescu Arina, Tokar Adriana
Abstract: The study includes both the estimation of the total emission of CO2 exhausted by a vehicle equipped with spark ignition engine and the opacity control during testing on the chassis dynamometer in the Road Vehicles Lab of Politehnica University of Timi?oara. The total CO2 estimations were accomplished by DEKRA software assuming that the vehicle is used 60% in urban traffic and 40% in the extra urban. Vehicle testing on the chassis dynamometer LPS 3000 has been achieved in different operating modes, in order to survey the gas opacity with AVL Dicom 4000 analyzer.
Keywords: Pollutant emissions, internal combustion engine, chassis dynamometer, traffic, gases analyzer
Title of the Paper: Variation of CO2, HC, NOX Emissions for an EURO III Engine under Urban Traffic Conditions
Authors: Tokar Adriana, Negoitescu Arina
Abstract: In the experimental study were controlled CO2, HC and NOx emissions resulted from combustion into the engine which equips the Dacia Logan 1.4 MPI EURO III car. The experimental simulation of running in traffic conditions was performed on the LPS 3000 chassis dynamometer together with the AVL DiCom 4000 gas analyzer in order to measure the pollutant emissions. Different experimental situations in traffic operation were simulated by activating the stand LPS 3000 braking system, maintaining a constant traction F=0N and F=200N. The tests were accomplished in the Road Vehicles Laboratory from University Politehnica of Timi?oara. It was noticed that high CO2 and NOx values were recorded in the fuel rich mixtures areas and high HC values in the poor mixtures area.
Keywords: Pollutant emissions, chassis dynamometer, gas analyzer, vehicle, traffic conditions
Title of the Paper: Heat Transfer and Dynamics of the Droplet on a Superheated Surface
Authors: Ivan V. Kazachkov
Abstract: The conditions governing the collapse of a "Leidenfrost drop", e.g. a liquid drop supported by a vapour film on a heated surface was studied analytically. Robust analytical model for the phenomenon has been developed and numerical simulation has been done. The model was represented by two second-order non-linear differential equations for the radius of evaporating drop and its distance over the heated surface. The results obtained have shown the high-frequent oscillations of the drop over the hot plate until complete evaporation of the drop occurs. In contrast with existing precise complex models, the mathematical model developed was simple and could be used for the qualitative estimation of different parameters and quantitative estimation of the integral behaviours of the drop such as time for complete drop evaporation. The effects of surfactants on the Leidenfrost phenomenon and its industrial applications were discussed
Keywords: Hot Plate; Droplet; Evaporation; Vapour Film; Oscillation; Leidenfrost phenomenon
Issue 3, Volume 7, July 2012
Title of the Paper: Simulation of Production and Injection Process in Geothermal Reservoir Using Finite Difference Method
Authors: Alamta Singarimbun, Mitra Djamal, Septian Setyoko
Abstract: The geothermal energy is well known as a renewable and clean energy. A step to understand and to estimete the geothermal energy is by using a reservoir modeling development. In this study, a mathematical and numerical modeling are performed to simulate a geothermal reservoir with injection and production well attached in the reservoir. Mathematical modeling performed obeys a Darcy's law, mass balance, energy balance, and also applying the finite difference method to get the model for the entire reservoir system. Numerical modeling is also performed in this study for calculating the variables. The results that obtained in this study are the distribution of temperature, pressure, enthalpy and fluid flow direction in the reservoir. These results will provide many information in the future. We can hope that a reservoir is expected to be designed with an appropriate management system.
Keywords: Geothermal energy, numerical modeling, Darcy's law, mass balance, energy balance, finite difference method
Title of the Paper: Numerical Simulation of Mass Transfer Aiming at Food Processes and Bioprocesses in Fixed-Bed Equipment: a Comparison Between Finite-Differences and Lattice-Bolztmann Method
Authors: José A. Rabi
Abstract: Lattice-Boltzmann method (LBM) has been alternatively used to numerically simulate mass transfer in porous media. Supercritical fluid extraction (SFE) and biospecific affinity chromatography (BAC) are fixedbed processes that may benefit from LBM as their model frameworks are very similar. By allowing the species concentration in the fluid phase to vary both in time and along the bed axis, this work has simplified SFE and BAC models in order to obtain an identical governing partial differential equation (PDE). Cast in dimensionless form, such mutual PDE was numerically solved through either LBM or finite-differences method (FDM). As far as false diffusion is concerned, numerical simulations were compared and results encourage the use of LBM as a simulation tool to investigate either SFE or BAC processes.
Keywords: Mass transfer, fixed bed, porous media, numerical simulation, finite-differences method, lattice-Boltzmann method
Title of the Paper: HVAC Analysis of a Building Installed Shape-Stabilized Phase Change Material Plates Coupling an Active Building Envelope System
Authors: Bor-Jang Tsai, Sheam-Chyun Lin, Wei-Cheng Yang
Abstract: Shape-stabilized phase change material (SSPCM) plates combined with night ventilation in summer is investigated numerically. A building in Hsinchu, Taiwan without active air-conditioning is considered for analysis, which includes SSPCM plates as inner linings of walls? the ceiling and floor, and an active building envelope system (ABE) is installed as well in the room becomes the Hybrid system. In the present study, a kind of floor with SSPCM is put forward which can absorb the solar radiation energy in the daytime or in summer and release the heat at night or in winter. In this paper, the thermal performance of a room using such floor?wall and ceiling were numerically studied. Results show that the average indoor air temperature of a room with the SSPCM floor was about 2 K to 4 K higher than that of the room without SSPCM floor, and the indoor air temperature swing range was narrowed greatly. This manifests that applying SSPCM in room suitably can increase the thermal comfort degree and save space heating energy in winter.
Keywords: Shape-stabilized phase change material, Active building envelope system, HVAC, Renewable energy
Issue 4, Volume 7, October 2012
Title of the Paper: Fast Numerical Calculation of Conduction Shape Factors with the Finite Element Method in the COMSOL Platform
Authors: Antonio Campo, Diego J. Celentano, Justin E. Robbins
Abstract: The heat conduction across a collection of square modules forming a large plane wall is a one–dimensional problem, whereas the heat conduction across a collection of scalloped modules forming a large corrugated wall is a two–dimensional problem. In this work, the two dimensional heat conduction equation for three different scalloped modules derived from the square module is solved numerically with the Finite Element Method in the platform of COMSOL Multiphysics. When the temperature fields in the modules are post-processed, the conduction shape factors S to be used in the algebraic formula Q=kS(TH-TC) can be easily determined. The heat conductive increments provided by the derived scalloped modules are qualitatively compared with the square module, subsequently accounting for beneficial mass reductions.
Keywords: Large plane wall, stackable square modules, large corrugated wall, stackable scalloped modules, incremental heat conduction, mass reduction
Title of the Paper: Drying of Palm Oil Fronds in Solar Dryer with Finned Double-Pass Solar Collectors
Authors: Ahmad Fudholi, Mohd Hafidz Ruslan, Mohd Yusof Othman, Mohd Syahriman Mohd Azmi, Azami Zaharim, Kamaruzzaman Sopian
Abstract: Solar drying system is very environment friendly and will enhance energy conservation. However, one of the main disadvantages of solar energy system is the problem associated with the intermittent nature of solar radiation and the low intensities of solar radiation in solar thermal systems. Many design of using solar systems for drying of agricultural products. A solar dryer system suitable for agricultural products have been designed, constructed and evaluated under the Malaysia climate conditions. The main components of the system are double-pass solar collector with finned absorber, the blower, the auxiliary heater and the drying chamber. The solar drying system has been evaluated for drying the oil palm fronds. For 100 kg palm oil fronds, the drying time is about of 3 drying day in sunny day (without heater) from an initial moisture content of 60% to the final moisture content of 10% (wb). A temperature of 55 oC can be reached at a solar radiation level of 650 W/m2, and mass flow rate of 0.13 kg/s, the overall system efficiency is about 20%.
Keywords: Finned double-pass solar collector, palm oil fronds, performance
Title of the Paper: Performance of Desiccant wheel for Low Humidity Drying System
Authors: Tri Suyono, Kamaruzzaman Sopian, Sohif Mat, Muhammad Yahya, Mohd Hafidz Ruslan, Mohd Yusuf Sulaiman, Azami Zaharim
Abstract: Drying is an important process for preserving food and non-food products. Solar desiccant drying system has been designed and fabricated for the production of dried products. The system has controllable drying temperature, humidity and flow rate of commercial/industrial capacity in accordance with the characteristics of the material, so that it is not damaged in the drying process. This system consists of heat pipe evacuated tube, cross flow heat exchanger, desiccant wheel, hot water pump, the hot water tank, drying chamber and electrical air heater. Experiments were conducted with two modes: (1) Heat exchanger to heat the air in the regeneration process and (2) Heat exchanger to heat the air after the dehumidification process, while the regeneration process utilized an electrical air heater. Experiment on the desiccant wheel of mode (1) showed that the average effectiveness of sensible dehumidification, sensible regeneration, latent dehumidification and latent regeneration were 72.61%, 82.13%, 79.32% and 78.91% respectively. In mode (2), the average effectiveness of sensible dehumidification, sensible regeneration, latent dehumidification and latent regeneration were 71.4%, 71.99%, 66.97% and 72.8% respectively. Mode (1) was better than mode (2) with mean drying air temperature and absolute humidity were 58oC and 0.0167 kg(H2O)/kg(dry air) respectively. The system was able to evaporate 10.8 kg(H2O)/hr of water in the materials at drying efficiency of 60%.
Keywords: Desiccant wheel, temperature and humidity, water evaporation
