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01775 A critical look at the air infiltration term in the Canadian energy rating procedure for windows
12 Refractories~ceramics (properties, production, applications) 06/01774 Thermal management of Li-ion battery with phase change material for electric scooters: experimental validation Khateeb, S. A. et al. Journal of Power Sources, 2005, 142, (1-2), 345 353. This work reports the laboratory test results of a Li-ion battery designed for electric scooter applications. Four different modes of heat dissipation were investigated in this experimental study: (1) natural convection cooling; (2) presence of aluminium foam heat transfer matrix; (3) use of phase change material (PCM); and (4) combination of aluminium foam and PCM. The objective of using the PCM is to lower the temperature rise of the Li-ion cells and create a uniform temperature distribution in the battery module. This is clearly justified looking at the experimental results presented in this work. The use of high thermal conductivity aluminium foam in the voids between the cells reduces the temperature rise of the Li-ion cells but is insufficient when operated in high ambient temperature such as those usually occur in summer. The use of aluminium foam with PCM causes a significant temperature drop of about 50% compared to the first case of no thermal management. It also provides uniform temperature distribution within the battery module, which is important for the efficient performance of the cells used. The laboratory results were modelled using a 2-D thermal model accounting for the four different modes of heat dissipation and good agreement was obtained between the simulation and experimental results.
simplified approximations of spherical harmonics are efficient and sufficiently accurate. They are a significant improvement of the classical diffusion models.
06/01777 An experimental study of energy balance in low heat rejection diesel engine Taymaz, I. Energy, 2006, 31, (2-3), 364-371. In a conventional internal combustion engine, approximately one-third of total fuel input energy is converted to useful work. Since the working gas in a practical engine cycle is not exhausted at ambient temperature, a major part of the energy is lost with the exhaust gases. In addition, another major part of energy input is rejected in the form of heat via the cooling system. If the energy normally rejected to the coolant could be recovered instead on the crankshaft as useful work, then a substantial improvement in fuel economy would result. In this study, the effect of insulated heat transfer surfaces on diesel engine energy balance system was investigated. The research engine was a fourstroke, direct injected, six cylinder, turbocharged and inter-cooled diesel engine. This engine was tested at different speeds and load conditions without coating. Then, combustion chamber surfaces, cylinder head, valves and piston crown faces were coated with ceramic materials. Ceramic layers were made of CaZrO3 and MgZrO3 and plasma coated onto base of the NiCrA1 bond coat. The ceramic-coated research engine was tested at the same operation conditions as the standard (without coating) engine. The results indicate a reduction in fuel consumption and heat losses to engine cooling system of the ceramic-coated engine.
06/01778 Complex multimaterial insulating frames for windows with evacuated glazing
12 REFRACTORIES/ CERAMICS Properties, production, applications 06/01775 A critical look at the air infiltration term in the Canadian energy rating procedure for windows Bernier, M. and Hall6, S. Energy and Buildings, 2005, 37, (10), 997 1006. This article examines the thermal effects of air infiltration/exfiltration in windows and proposes a modification to the Canadian energy rating procedure for windows to account for the associated energy losses. The proposed equation takes into consideration: (i) the thermal interaction between the frame and the air that infiltrates; (ii) the variation of the infiltration rate with meteorological conditions; and (iii) the increase of the infiltration rate at low temperatures. The proposed method is applied to various types of windows and five Canadian climates. Results show that losses associated with air infiltration are somewhat negligible when compared to conduction losses and solar gains. It is also shown that the current calculation in the Canadian energy rating for windows overestimates the infiltration energy losses.
06/01776 Adaptive solutions of SPN-approximations to radiative heat transfer in glass Klar, A. et al. International Journal of Thermal Sciences, 2005, 44, (11), 1013 1023. This paper presents numerical models of radiative heat transfer in glass manufacturing that can be performed on normal workstations, yet are sufficiently accurate for many practical applications. Since many of the glass production processes are so complex that a complete simulation is still unthinkable at present, there is a great interest for such models in order to optimize final glass products. The authors use simplified approximations of spherical harmonics to obtain approximate solutions of high accuracy in optically thick regimes, The arising systems of partial differential-algebraic equations of mixed parabolic-elliptic type are numerically solved by a self-adaptive discretization method based on an error-controlled finite element method in space and a one-step method of Rosenbrock-type with variable step sizes in time. The method itself judges the quality of the numerical solutions and determines adaptive strategies to keep the discretization error below a user-prescribed tolerance. Multilevel techniques based on reliable and efficient a posteriori error estimators and time embedding are used to improve the spatial discretization by local refinement and to steer the step size selection routine. The authors present numerical results for a typical step in glass manufacturing, the cooling of a glass cube. The approximate solutions are validated with solutions to the full radiative transport equation and compared to Rosseland approximations widely used in the engineering practice. The results show that
Fang, Y. et al. Solar Energy, 2005, 79, (3), 245 261. The thermal performance of a complex multimaterial frame consisting of an exoskeleton framework and cavities filled with insulant materials enclosing an evacuated glazing was simulated using a two-dimensional finite element model and the results were validated experimentally using a guarded hot box calorimeter. The analysed 0.5 m by 0.5 m evacuated glazing consisted of two low-emittance film coated glass panes supported by an array of 0.32 m m diameter pillars spaced 25 m m apart, contiguously sealed by a 10 m m wide metal edge seal. Thermal performance of windows employing evacuated glazing set in various complex multimaterial frames were analysed in detail. Very good agreement was found between simulations and experimental measurements of surface temperatures of the evacuated glazing window system. The heat loss from a window with an evacuated glazing and a complex multimaterial frame is about 80% of that for a window comprised of an evacuated glazing set in a single material solid frame.
06/01779 Glass transition and crystallite melting in natural organic matter Chilom, G. and Rice, J. A. Organic" Geochemistry, 2005, 36, (10), 1339 1346. The presence of (CH2),, crystalline components in lipid extracts from soil and peat was detected by solid-state N M R and X-ray diffraction. The lipid fractions were extracted from geosorbents including the IHSS Pahokee peat and leonardite, a second peat and its humic acid. The existence of two peaks in the 30-33 ppm N M R shift region demonstrates the presence of semicrystalline carbon in the lipid fraction, presumably in long aliphatic chains. X-ray diffraction patterns of the lipid fractions are similar to polyethylene, with the strongest reflections at 4.13 and 3.72 A. The melting temperatures of the lipid fractions vary among the geosorbents and are in the same temperature interval with the glass transition reported in the literature for the IHSS peat and leonardite. After removing the fraction containing the crystalline components, the leonardite and Guanella Pass peat humic acid do not show any thermal events in their respective DSC thermograms. This finding suggests that, at least for the systems studied, the reported glass transition was actually the melting of the crystallites present in the lipid fraction.
06/01780 Heat transfer model of semi-transparent ceramics undergoing laser-assisted machining Pfefferkorn, F. E. et al. International Journal of Heat and Mass' Transfer, 2005, 48, (10), 1999 2012. A three-dimensional, unsteady heat transfer model has been developed for predicting the temperature field in partially stabilized zirconia (PSZ) undergoing laser-assisted machining. The semi-transparent PSZ is treated as optically thick within a spectral band from approximately 0.5 to 8 mm. After comparing the diffusion approximation and the discrete ordinates method for predicting internal radiative transfer, suitability of the diffusion approximation is established from a comparison of model predictions with surface temperature measurements. The temperature predictions are in good agreement with measured values during machining. Parametric calculations reveal that laser power and feedrate have the greatest effect on machining temperatures.
Fuel and Energy Abstracts
July 2006 271
simplified approximations of spherical harmonics are efficient and sufficiently accurate. They are a significant improvement of the classical diffusion models.
06/01777 An experimental study of energy balance in low heat rejection diesel engine Taymaz, I. Energy, 2006, 31, (2-3), 364-371. In a conventional internal combustion engine, approximately one-third of total fuel input energy is converted to useful work. Since the working gas in a practical engine cycle is not exhausted at ambient temperature, a major part of the energy is lost with the exhaust gases. In addition, another major part of energy input is rejected in the form of heat via the cooling system. If the energy normally rejected to the coolant could be recovered instead on the crankshaft as useful work, then a substantial improvement in fuel economy would result. In this study, the effect of insulated heat transfer surfaces on diesel engine energy balance system was investigated. The research engine was a fourstroke, direct injected, six cylinder, turbocharged and inter-cooled diesel engine. This engine was tested at different speeds and load conditions without coating. Then, combustion chamber surfaces, cylinder head, valves and piston crown faces were coated with ceramic materials. Ceramic layers were made of CaZrO3 and MgZrO3 and plasma coated onto base of the NiCrA1 bond coat. The ceramic-coated research engine was tested at the same operation conditions as the standard (without coating) engine. The results indicate a reduction in fuel consumption and heat losses to engine cooling system of the ceramic-coated engine.
06/01778 Complex multimaterial insulating frames for windows with evacuated glazing
12 REFRACTORIES/ CERAMICS Properties, production, applications 06/01775 A critical look at the air infiltration term in the Canadian energy rating procedure for windows Bernier, M. and Hall6, S. Energy and Buildings, 2005, 37, (10), 997 1006. This article examines the thermal effects of air infiltration/exfiltration in windows and proposes a modification to the Canadian energy rating procedure for windows to account for the associated energy losses. The proposed equation takes into consideration: (i) the thermal interaction between the frame and the air that infiltrates; (ii) the variation of the infiltration rate with meteorological conditions; and (iii) the increase of the infiltration rate at low temperatures. The proposed method is applied to various types of windows and five Canadian climates. Results show that losses associated with air infiltration are somewhat negligible when compared to conduction losses and solar gains. It is also shown that the current calculation in the Canadian energy rating for windows overestimates the infiltration energy losses.
06/01776 Adaptive solutions of SPN-approximations to radiative heat transfer in glass Klar, A. et al. International Journal of Thermal Sciences, 2005, 44, (11), 1013 1023. This paper presents numerical models of radiative heat transfer in glass manufacturing that can be performed on normal workstations, yet are sufficiently accurate for many practical applications. Since many of the glass production processes are so complex that a complete simulation is still unthinkable at present, there is a great interest for such models in order to optimize final glass products. The authors use simplified approximations of spherical harmonics to obtain approximate solutions of high accuracy in optically thick regimes, The arising systems of partial differential-algebraic equations of mixed parabolic-elliptic type are numerically solved by a self-adaptive discretization method based on an error-controlled finite element method in space and a one-step method of Rosenbrock-type with variable step sizes in time. The method itself judges the quality of the numerical solutions and determines adaptive strategies to keep the discretization error below a user-prescribed tolerance. Multilevel techniques based on reliable and efficient a posteriori error estimators and time embedding are used to improve the spatial discretization by local refinement and to steer the step size selection routine. The authors present numerical results for a typical step in glass manufacturing, the cooling of a glass cube. The approximate solutions are validated with solutions to the full radiative transport equation and compared to Rosseland approximations widely used in the engineering practice. The results show that
Fang, Y. et al. Solar Energy, 2005, 79, (3), 245 261. The thermal performance of a complex multimaterial frame consisting of an exoskeleton framework and cavities filled with insulant materials enclosing an evacuated glazing was simulated using a two-dimensional finite element model and the results were validated experimentally using a guarded hot box calorimeter. The analysed 0.5 m by 0.5 m evacuated glazing consisted of two low-emittance film coated glass panes supported by an array of 0.32 m m diameter pillars spaced 25 m m apart, contiguously sealed by a 10 m m wide metal edge seal. Thermal performance of windows employing evacuated glazing set in various complex multimaterial frames were analysed in detail. Very good agreement was found between simulations and experimental measurements of surface temperatures of the evacuated glazing window system. The heat loss from a window with an evacuated glazing and a complex multimaterial frame is about 80% of that for a window comprised of an evacuated glazing set in a single material solid frame.
06/01779 Glass transition and crystallite melting in natural organic matter Chilom, G. and Rice, J. A. Organic" Geochemistry, 2005, 36, (10), 1339 1346. The presence of (CH2),, crystalline components in lipid extracts from soil and peat was detected by solid-state N M R and X-ray diffraction. The lipid fractions were extracted from geosorbents including the IHSS Pahokee peat and leonardite, a second peat and its humic acid. The existence of two peaks in the 30-33 ppm N M R shift region demonstrates the presence of semicrystalline carbon in the lipid fraction, presumably in long aliphatic chains. X-ray diffraction patterns of the lipid fractions are similar to polyethylene, with the strongest reflections at 4.13 and 3.72 A. The melting temperatures of the lipid fractions vary among the geosorbents and are in the same temperature interval with the glass transition reported in the literature for the IHSS peat and leonardite. After removing the fraction containing the crystalline components, the leonardite and Guanella Pass peat humic acid do not show any thermal events in their respective DSC thermograms. This finding suggests that, at least for the systems studied, the reported glass transition was actually the melting of the crystallites present in the lipid fraction.
06/01780 Heat transfer model of semi-transparent ceramics undergoing laser-assisted machining Pfefferkorn, F. E. et al. International Journal of Heat and Mass' Transfer, 2005, 48, (10), 1999 2012. A three-dimensional, unsteady heat transfer model has been developed for predicting the temperature field in partially stabilized zirconia (PSZ) undergoing laser-assisted machining. The semi-transparent PSZ is treated as optically thick within a spectral band from approximately 0.5 to 8 mm. After comparing the diffusion approximation and the discrete ordinates method for predicting internal radiative transfer, suitability of the diffusion approximation is established from a comparison of model predictions with surface temperature measurements. The temperature predictions are in good agreement with measured values during machining. Parametric calculations reveal that laser power and feedrate have the greatest effect on machining temperatures.
Fuel and Energy Abstracts
July 2006 271