Showing papers in "Heat Transfer Research in 2006"
TL;DR: In this article, the submodels of a flash-boiling spray are constructed and the model is implemented in KIVA3V and the spray characteristics of multicomponent fuel with and without flashing are numerically investigated.
Abstract: Flash-boiling occurs when a fuel is injected into a combustion chamber where the ambient pressure is lower than the saturation pressure of the fuel It has been known that flashing is a favorable mechanism for atomizing liquid fuels On the other hand, alternative fuels, such as gaseous fuels and oxygenated fuels, are used to achieve low exhaust emissions in recent years In general, most of these alternative fuels have high volatility and flash-boiling takes place easily in the fuel spray when injected into the combustion chamber of an internal combustion engine under high pressure In addition the multicomponent mixture of high- and low-volatility fuels has been proposed in the previous study in order to control the spray and combustion processes in an internal combustion engine It was found that the multicomponent fuel produces flash-boiling with an increase in the initial fuel temperature Therefore, it is important to investigate these flash-boiling processes in fuel spray
In the present study, the submodels of a flash-boiling spray are constructed These submodels consider the bubble nucleation, growth, and disruption in the nozzle orifice and injected fuel droplets The model is implemented in KIVA3V and the spray characteristics of multicomponent fuel with and without flashing are numerically investigated In addition, these numerical results are compared with experimental data obtained in the previous study using a constant volume vessel The flashing spray characteristics from numerical simulation qualitatively show good agreement with the experimental results In particular, it is confirmed from both the numerical and experimental data that flash-boiling effectively accelerates the atomization and vaporization of fuel droplets This means that a lean homogeneous mixture can be quickly formed using flash-boiling in the combustion chamber © 2006 Wiley Periodicals, Inc Heat Trans Asian Res, 35(5): 369–385, 2006; Published online in Wiley InterScience (wwwintersciencewileycom) DOI 101002/htj20117
42 citations
TL;DR: In this paper, the authors measured the properties of liquid and supercooled tungsten using noncontact techniques in combination with an electrostatic levitator and obtained a volume expansion coefficient of 6.6×10−5 K−1.
Abstract: Thermophysical properties of liquid and supercooled tungsten were measured using non-contact techniques in combination with an electrostatic levitator. Over the 3125–3707 K temperature range, the density measurements can be expressed as ρ (T) = 16.7(± 0.33)× 103 − 1.08(± 0.08) (kgċ m−3) with Tm = 3695 K, leading to a volume expansion coefficient of 6.6×10−5 K−1. In addition, over the 3398–3695 K temperature range, the surface tension (γ) and viscosity (η) data can be expressed respectively as γ (T) = 2.48× 103(± 75) − 0.31(± 0.08) (T − Tm) (10−3 Nċ m−1) and η (T) = 0.11(± 0.02) exp[12.8(± 4.1) × 104/(RT)] (10−3 Paċ s). © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(2): 152–164, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20101
22 citations
TL;DR: In this paper, a transient core analysis of a small molten salt reactor (MSR) when a duct blockage accident occurred was performed, and the results showed that the effect of the self-control performance of the MSR on the effective multiplication factor and thermal power output was insignificant.
Abstract: This paper reports the results from a transient core analysis of a small molten salt reactor (MSR) when a duct blockage accident occurred. The focus of this study is a numerical model employed in order to consider the interaction among fuel salt flow, heat transfer, and nuclear reactions. The numerical model comprises continuity and momentum conservation equations for fuel salt flow, two-group neutron diffusion equations for fast and thermal neutron fluxes, transport equations for six-group delayed neutron precursors, and energy conservation equations for fuel salt and graphite moderators. The analysis results show the following: (1) the effect of the self-control performance of the MSR on the effective multiplication factor and thermal power output of the reactor after the blockage accident is insignificant, (2) fuel salt and graphite moderator temperatures increase drastically but locally at the blockage area and its surroundings, (3) the highest fuel salt temperature after the blockage accident is 1,363 K; this value is lower than the boiling point of fuel salt and the melting temperature of the reactor vessel, (4) the change in the distributions of fast and thermal neutron fluxes after the blockage accident when compared with the distributions at the rated condition is very slight, and (5) delayed neutron precursors, especially the first delayed neutron precursor, accumulate at the blockage area due to its large decay constant. These results imply that the safety of the MSR is assured in the case of a blockage accident. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(6): 434–450, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20123
21 citations
TL;DR: In this article, two types of fire simulation software, CFAST and FDS, were used to reconstruct a motorcycle shop fire accident in Taiwan, and the impact of natural/forced ventilation on the fire was also studied.
Abstract: Accidental building fires present considerable valuable information on fire phenomena and behavior. However, fire and smoke movement quantitative data cannot be obtained directly from a building fire accident. Therefore, computational methods have been widely used to reestablish the fire scenario and obtain a great deal of information for fire study. This paper utilized two types of fire simulation software, CFAST and FDS, to reconstruct a motorcycle shop fire accident in Taiwan. Important thermodynamic parameters during the fire duration were obtained through numerical simulations. The impact of natural/forced ventilation on the fire was also studied. The results showed that the more forced airflow into the building, the more time people had to evacuate to a safe place from the fire. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(6): 387–401, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20127
18 citations
15 citations
15 citations
TL;DR: In this paper, the effect of surface wettability on evaporation of a water drop has been examined experimentally using surfaces with various contact angles, and the relationship between the contact angle and the wetting limit temperature was obtained.
Abstract: The effect of surface wettability on evaporation of a water drop has been examined experimentally using surfaces with various contact angles. To greatly change the surface wettability, TiO2 superhydrophilicity, plasma irradiation, and super-water-repellent surface are adopted as the heating surface. The range in contact angle achieved by these methods was between 0° and 170°. The relationship between the contact angle and the wetting limit temperature was obtained and it was found that the lifetime of a water drop dramatically decreases with contact angle in the lower temperature region, and that the wetting limit temperature increases with the contact angle. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(7): 513–526, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20128
15 citations
TL;DR: In this article, the authors proposed an innovative non-tracking three-dimensional compound parabolic concentrator (3-D CPC) solar collector, which has excellent thermal efficiency for a high-temperature range (100-200°C).
Abstract: In this paper, the authors propose an innovative non-tracking three-dimensional compound parabolic concentrator (3-D CPC) solar collector, which has excellent thermal efficiency for a high-temperature range (100–200°C). In the past studies, in order to improve the thermal efficiency of the solar collector in a high-temperature range, very high concentration ratios and tracking systems have been adopted. However, conventional high concentration solar collectors are not cost-effective and are inappropriate for small-rating thermal electric generation systems for residential use. The proposed 3-D CPC collector has a moderate concentration ratio and does not need tracking. Initially, the tentative 3-D CPC collector was fabricated and its thermal performance was tested. Next, numerical simulations of the optical characteristics of the 3-D CPC collector were carried out via the ray-tracing method. Finally, the specification of the optimal 3-D CPC collector was clarified. Applications of the thermal electric system will also be mentioned. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(5): 323–335, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20121
13 citations
12 citations
TL;DR: In this article, the authors investigated the non-uniform heat flux distribution along the circumferential direction by using the Joule heating of SUS304 tubes with the wall thickness distribution, and the experimental results showed an increase in the critical heat flux substantiated by the existence of the redistribution of the flow.
Abstract: In an actual boiling channel, e.g., a boiler water-tube, the circumferential heat flux is not uniform. Thus, the critical heat flux (CHF) of a non-uniformly heated tube becomes an important design factor for conventional boilers, especially for a compact water-tube boiler with a tube-nested combustor. A small compact boiler is operated under low-pressure and low-mass-flux conditions compared with a large-scale boiler, thus the redistribution of liquid film strongly affects the characteristics of CHF. In this investigation, non-uniform heat flux distribution along the circumferential direction was generated by using the Joule heating of SUS304 tubes with the wall thickness distribution. The heated length of test-section was 900 mm with an inner diameter of 20 mm and an outer diameter of 24 mm. The center of the inner tube surface was shifted by e=0, 0.5, 1.0, 1.5 mm from the center of the outer tube surface. The heat flux ratio between maximum and minimum heat flux of these tubes corresponded to 1.0, 1.7, 3.0, and 7.0, respectively. The experimental conditions were as follows: system pressure at 0.3 and 0.4 MPa, mass flux of 10–100kg/(m2s), inlet temperatures at 30° and 80°. The experimental results showed an increase in the critical heat flux substantiated by the existence of the redistribution of the flow. These characteristics are explained by using a concept similar to that of Butterworth's spreading model. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 47–60, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20095
11 citations
TL;DR: In this paper, visual experiments were conducted to observe droplet oscillation on horizontal surfaces with air flow, and the results indicated that the oscillating characteristics were closely dependent on surface roundness, droplet size, and air flow velocity.
Abstract: Visual experiments were conducted to observe droplet oscillation on horizontal surfaces with air flow. The different Cu test surfaces were polished with different grit sandpapers. Two liquid drop oscillation modes, forward-backward and upward-downward, were visually observed in the experiments. Additionally these two modes were observed to transition from one to another under some conditions. The results indicate that the oscillating characteristics were closely dependent on surface roundness, droplet size, and air flow velocity. A larger radius and higher air speed would decrease the oscillation frequency, while the frequency would initially decrease and then increase as the roughness changed from the smooth to rough plates. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 13–19, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20098
TL;DR: In this paper, the micro-layer thickness was measured applying the laser extinction method for channel gap sizes of 05, 03, and 15 mm for micro-channel vaporization.
Abstract: To elucidate the mechanism and characteristics of boiling heat transfer in a micro-channel vaporizer, the experimental investigation of the micro-layer thickness that formed between the heating surface and vapor generated was important The micro-layer thickness was measured applying the laser extinction method for channel gap sizes of 05, 03, and 015 mm It was clarified that the gap size, the rate of bubble growth, and the distance from the incipient bubble site have an effect on the micro-layer thickness in a micro-channel boiling system The initial micro-layer thickness grew with an increase of the velocity of bubble forefront to moderate the value of the velocity In the region of greater velocity, the thickness was constant for each gap The distributions of the initial thickness of micro-layer on the heat transfer surface were shown © 2005 Wiley Periodicals, Inc Heat Trans Asian Res, 35(1): 35–46, 2006; Published online in Wiley InterScience (wwwintersciencewileycom) DOI 101002/htj20096
TL;DR: In this paper, a two-dimensional mathematical model of a simplified RSCP combustor is developed based on the hypothesis of local thermal non-equilibrium between the solid and the gas phases by solving separate energy equations for these two phases.
Abstract: The influences of thermophysical properties of porous media on superadiabatic combustion with reciprocating flow is numerically studied in order to improve the understanding of the complex heat transfer and optimum design of the combustor. The heat transfer performance of a porous media combustor strongly depends on the thermophysical properties of the porous material. In order to explore how the material properties influence reciprocating superadiabatic combustion of premixed gases in porous media (short for RSCP), a two-dimensional mathematical model of a simplified RSCP combustor is developed based on the hypothesis of local thermal non-equilibrium between the solid and the gas phases by solving separate energy equations for these two phases. The porous media is assumed to emit, absorb, and isotropically scatter radiation. The finite-volume method is used for computing radiation heat transfer processes. The flow and temperature fields are calculated by solving the mass, moment, gas and solid energy, and species conservation equations with a finite difference/control volume approach. Since the mass fraction conservation equations are stiff, an operator splitting method is used to solve them. The results show that the volumetric convective heat transfer coefficient and extinction coefficient of the porous media obviously affect the temperature distributions of the combustion chamber and burning speed of the gases, but thermal conductivity does not have an obvious effect. It indicates that convective heat transfer and heat radiation are the dominating ways of heat transfer, while heat conduction is a little less important. The specific heat of the porous media also has a remarkable impact on temperature distribution of gases and heat release rate. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(5): 336–350, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20120
TL;DR: In this article, the authors solve the problem of determining the frequency and amplitude of oscillations caused by the precession of a helical vortex core in the suction tube of a hydroturbine from the specified integral characteristics: vortex intensity, liquid flow rate, and momentum and moment of momentum fluxes.
Abstract: DTU Orbit (28/01/2019) Simulation of flow structure in the suction pipe of a hydroturbine by integral characteristics Within the framework of a model of a twisted flow of an inviscid incompressible liquid, we solve the problem of determining the frequency and amplitude of oscillations caused by the precession of a helical vortex core in the suction tube of a hydroturbine from the specified integral characteristics: vortex intensity, liquid flow rate, and momentum and moment of momentum fluxes. © 2006 Begell House, Inc.
TL;DR: In this paper, double-walled carbon nanotubes (DWNTs) were generated from a peapod structure, defined by five C60 molecules inside a (10,10) single-Walled carbon Nanotube (SWNT), polymerized fullerenes, and an almost nanotube-like structure.
Abstract: The generation process of a double-walled carbon nanotube (DWNT) from a “peapod” was studied by classical molecular dynamics simulation. Starting from a peapod structure, defined by five C60 molecules inside a (10,10) single-walled carbon nanotube (SWNT), polymerized fullerenes, a peanut-like structure and an almost nanotube-like structure were obtained under suitable conditions of temperature control. The mean distance between the two layers of the DWNT agreed with an experimental report that it is larger than the interlayer spacing found in multi-walled carbon nanotubes (MWNTs). In addition, the chirality dependence of the potential energy of a DWNT on the relative chirality of its constituent tubes was examined using a 6-12 Lennard-Jones potential. It was found that the potential energy depends only on the distance between the two layers, not on the relative chiralities. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 254–264, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20115
TL;DR: In this article, the authors describe the pressure drop characteristics of finned tube banks used for heat exchangers in thermal power generation that were clarified by testing serrated and spiral finned tubes with different fin heights for improved heat transfer.
Abstract: In recent years the requirement for the reduction of energy consumption has been increasing to solve the problems of global warming and the shortage of petroleum resources. For example, in the power generation field, as thermal power generation occupied 60% of the power generation demand, considerable improvement of the thermal efficiency is required. This paper describes the pressure drop characteristics of finned tube banks used for heat exchangers in thermal power generation that were clarified by testing serrated finned tube banks with different fin heights for improved heat transfer and conventional spiral finned tube banks with different fin heights, and an equation to predict pressure drop which is necessary for the heat exchanger design is proposed. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(3): 179–193, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20112
TL;DR: In this article, the effect of increased inclination and porosity coefficient of outlet openings on the cooling capability of a thin laptop PC was investigated, and the experimental data were reduced to a Nusselt number-Rayleigh number correlation, by using a modified reference length.
Abstract: Natural air-cooling technologies for electronic equipment have the important advantages of no fan and high reliability. However, natural air cooling has lower cooling capability than fan air cooling, so enhancement of its cooling capability is required. This paper presents the results for experimental casings designed to employ the chimney effect in natural air-cooled electronic equipment. The system casing is inclined to enhance the effectiveness of natural air cooling. Experiments were carried out using a thin laptop PC. We investigated the effect on cooling capability produced by inclining the casing and by varying the outlet positions and numbers and the porosity coefficient of the outlet openings. The results show that the temperatures inside the casing and heater surfaces are slightly diminished by the effect of increased inclination and porosity coefficient of outlet openings. Moreover, the increase in natural circulation flux in the casing was quantitatively proven by experiments. In addition, the experimental data were reduced to a Nusselt number–Rayleigh number correlation, , by using a modified reference length. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(2): 122–136, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20103
TL;DR: In this article, the heat transfer characteristics of finned tube banks used for the heat exchanger in thermal power generation were clarified by testing serrated tube banks with different fin heights for improved higher heat transfer.
Abstract: In recent years the requirement for the reduction of energy consumption has been increasing to solve the problems of global warming and the shortage of petroleum resources. For example, in the power generation field, as thermal power generation occupies 60% of the power generation demand, considerable improvement of thermal efficiency is required. This paper describes the heat transfer characteristics of finned tube banks used for the heat exchanger in thermal power generation that were clarified by testing serrated finned tube banks with different fin heights for improved higher heat transfer and conventional spiral finned tube banks with different fin height. Then an equation to predict the heat transfer coefficient which is necessary for the design of the heat exchanger was proposed. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(3): 194–208, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20111
TL;DR: In this article, the effect of the pore diameter of the porous plate on the humidity transport through a porous plate was found to depend strongly on the thickness and pore size of the plate.
Abstract: As a first step toward evaluating factors that influence humidity and heat transfer from moist air to dry air through porous media having very small pores, the present paper attempts to clarify factors that influence moisture transport between constant-temperature water and dry air through a porous media plate. The effect of the pore diameter of the porous plate on the humidity transport through a porous plate was found to depend strongly on the thickness and pore diameter of the porous plate. That is, the smaller the pore diameter and the thicker the plate, the greater the effect of the pore diameter on the humidity transfer. In addition, the performance of heat and mass transfer were confirmed to increase with respect to the increase of air velocity. In addition, a parameter called the humidity absorption rate was introduced to evaluate the utilization degree of the air capacity to absorb humidity. The humidity absorption rate decreased with increases in both air velocity and plate thickness. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(2): 137–151, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20102
TL;DR: In this article, the authors investigated turbulent combustion by particle image velocimetry (PIV) technique and found that the PIV estimated scale is very close to that of LDV based on the assumption of Taylor's hypothesis.
Abstract: We have investigated turbulent combustion by PIV (Particle Image Velocimetry) technique. Comparing with LDV data, the validity of PIV measurements has been confirmed. Particularly, the conditions of sampling number and spatial resolution have been shown to yield reliable data using PIV. Based on the velocity fields in cold flow and combustion, the interaction between flame and flow has been discussed. It was observed that the flow field is changed by combustion and the turbulence is reduced. In order to determine statistical quantities such as mean velocity and RMS of velocity fluctuation, a sampling number of 1000 is needed. Moreover, the velocity correlation coefficient was evaluated to obtain the integral length scale of the flow. For both cold flow and combustion, the PIV estimated scale is very close to that of LDV based on the assumption of Taylor's hypothesis. As a result, the spatial resolution in this study is about 6 times smaller than the integral length scale. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(7): 501–512, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20129
TL;DR: In this paper, the effect of solid properties on dynamic wetting was investigated using a liquid tank method, and the wetting behavior of silicone oil over glass, aluminum, and stainless steel surfaces was measured.
Abstract: An experimental investigation was conducted to understand the effect of solid properties on dynamic wetting. Using a liquid tank method, the wetting behavior of silicone oil over glass, aluminum, and stainless steel surfaces was measured. For all three surfaces, the dynamic contact angles disagreed with the universal function proposed by Hoffman. However, if a dimensionless parameter is introduced to describe the nature of the solid surfaces, the experimental results can be in good agreement with the model. Furthermore, the present experiments indicated that the Hoffman–Voinov–Tanner law should be valid for a wider range of dynamic contact angles or capillary numbers. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 1–12, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20099
TL;DR: In this paper, the effect of thermal boundary conditions on turbulent heat transfer in a channel flow was examined and the results indicated that the time scale ratio varies along the stream direction, indicating that the thermal boundary condition can influence the time-scale ratio.
Abstract: Direct numerical simulation (DNS) was performed for the turbulent heat transfer in a channel flow. In the present study, the effect of the thermal boundary condition was examined. DNS was carried out for varying streamwise thermal boundary conditions (Reτ = 180) with Pr = 0.71 to obtain statistical mean temperatures, temperature variances, budget terms, and time scale ratios. The results obtained indicate that the time scale ratio varies along the stream direction. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 265–278, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20114
TL;DR: In this article, the viscous characteristics of an EG solution with flow drag reduction additive have been investigated experimentally, and the experimental parameters of viscosity measurement were the temperature of the EG solution, the ODEAO concentration and the EG concentration.
Abstract: The viscous characteristics of ethylene glycol (EG) solution with flow drag reduction additive have been investigated experimentally. In this study, oleyldihydoroxyetyl amineoxide (ODEAO) was used as the flow drag reduction additive, and an aqueous solution of EG was used as a secondary refrigerant. The viscosity of the EG solution with ODEAO was measured with a rotational rheometer. The experimental parameters of viscosity measurement were the temperature of the EG solution with ODEAO, the ODEAO concentration, and the EG concentration. From the experimental results, the apparent viscosity of the EG solution with ODEAO showed SIS (shear induced state). The non-linear dependence of shear stress on shear rate has been well approximated by the power-law model under high shear conditions. The power-law contents, pseudoplastic viscosity, and index number have been estimated for each experimental parameter. Using the measured viscosity and non-dimensional analysis, the flow drag and heat transfer reduction effect of the EG solution with ODEAO has been investigated. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(8): 553–567, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20134
TL;DR: In this paper, a spherically symmetric one-dimensional analysis is applied to the abrupt heating process of a micro plastic resin particle in a high temperature inert atmosphere, by dividing the entire heating process into four independent periods.
Abstract: A fundamental understanding of the physical properties of a micro plastic-resin particle subjected suddenly to hot combustion gas, such as the temperature history in the micro particle and its lifetime, is necessary for effectively realizing thermal recycling of recycled plastic resin. However, micro plastic particles have such small diameters, ranging from 100 µm to 200 µm, that the measurement of temperature histories within them is extremely difficult. In this paper, therefore, a spherically symmetric one-dimensional analysis is applied to the abrupt heating process of a micro plastic resin particle in a high temperature inert atmosphere. Variations of the temperature history and the lifetime with the ambient gas temperature and the initial particle diameter are numerically analyzed, by dividing the entire heating process into four independent periods; the solid heating period, the melting period, the liquid heating period, and the vaporization period. Effects of the Nusselt number on the particle lifetime are also discussed. It is found that, by suitably taking account of the influences of heat transfer properties, the proposed simplified analysis is useful for estimating the fundamental and overall temperature characteristics of a micro plastic resin particle under abrupt heating. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(4): 279–293, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20113
TL;DR: In this paper, the authors proposed a technique of analysis that supports the optimization of layouts for vacuum insulation panels (VIPs) for refrigerators, using a one-dimensional technique of calculation to simulate the heat loss caused by VIP envelope materials.
Abstract: We proposed a technique of analysis that supports the optimization of layouts for vacuum insulation panels (VIPs) for refrigerators, using a one-dimensional technique of calculation to simulate the heat loss caused by VIP envelope materials. VIP thermal characteristics were described by approximating system efficiency by using the panels' average length (Lp). We compared this simplified method to three-dimensional numerical analysis of 1 to 6µm thick, vacuum-packed aluminum foil and 1.5 to 6 mW/mK thermally conductive heat-insulated core materials, and verified them to be within a 1% margin of error. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(7): 451–463, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20132
TL;DR: In this article, a two-dimensional steady, laminar flow model is used for the chemical kinetic model and thermal radiation transport of the porous media that is placed inside the burner is solved using the discrete ordinate method.
Abstract: Premixed combustion in a porous medium burner is investigated numerically. A two-dimensional steady, laminar flow model is used. A single-step reaction of methane is used for the chemical kinetic model. The model also includes thermal radiation transport of the porous media that is placed inside the burner. The radiative transport equation is solved by using the discrete ordinate method. The results show that, for each equivalence ratio, the flame can be stabilized at various axial locations with different flame speeds. The flame temperature increases with the equivalence ratio and flame speed. Furthermore, the energy release rates are much higher than that of a free flame for the same equivalence ratio as a result of higher flame speed. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 75–88, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20088