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Air Velocity (air + velocity)
Selected AbstractsThe resistance of packed beds of moth gram (Vigna aconitifolius) to airflowINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2006Prabhakar M. Nimkar Summary The resistance of packed beds of clean moth gram (Vigna aconitifolius) to airflow was studied at moisture contents varying from 5.64 to 19.42% dry basis (d.b.) and at superficial air velocities ranging between 0.0104 and 0.8321 m s,1 with bed depths of 0.2,0.6 m and bulk densities ranging from 745 to 875 kg m,3. The airflow resistance of moth gram increased with increase in airflow rate and bulk density and decreased with moisture content. Results indicated that a 13.78% increase in moisture content decreased the pressure drop by 26.58% whereas, a 7.7% increase in bulk density increased the pressure drop by 43%. The modified Shedd's equation and Hukill and Ives equation were evaluated to see if they predicted pressure drop accurately. Airflow resistance was accurately described by the modified Shedd's equation. The statistical model that related airflow rate and bulk density could fit pressure drop data reasonably well. For loose fill beds an increase in grain moisture content increased the minimum fluidization velocity value from 1.1009 to 1.2391 m s,1 whereas, for grain beds with 12.47% moisture content, the increase in bulk density decreased the minimum fluidization velocity value from 1.1152 to 1.0306 m s,1. [source] Effect of a gas,liquid separator on the hydrodynamics and circulation flow regimes in internal-loop airlift reactorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2001Jaroslav Klein Abstract The role of the gas,liquid separator on hydrodynamic characteristics in an internal-loop airlift reactor (ALR) was investigated. Both gas holdup and liquid velocity were measured in a 30,dm3 airlift reactor with two different head configurations: with and without an enlarged separator. A magnetic tracer method using a neutrally buoyant magnetic particle as flowfollower was used to measure the liquid velocity in all sections of the internal-loop airlift reactor. Average liquid circulation velocities in the main parts of the ALR were compared for both reactor configurations. At low air flow rates the separator had no influence on gas holdup, circulation velocity and intensity of turbulence in the downcomer and separator. At higher superficial air velocities, however, the separator design had a decisive effect on the hydrodynamic parameters in the downcomer and the separator. On the other hand, the gas holdup in the riser was only slightly influenced by the separator configuration in the whole range of air flow. Circulation flow regimes, characterising the behaviour of bubbles in the downcomer, were identified and the effect of the separator on these regimes was assessed. © 2001 Society of Chemical Industry [source] Progress in the Modelling of Air Flow Patterns in Softwood Timber KilnsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2004T.A.G. Langrish Progress in modelling air flow patterns in timber kilns using computational fluid dynamics (CFD) is reviewed in this work. These simulations are intended to predict the distribution of the flow in the fillet spaces between boards in a hydraulic model of a timber kiln. Here, the flow regime between the boards is transitional between laminar and turbulent flow, with Reynolds numbers of the order of 5000. Running the simulation as a transient calculation has shown few problems with convergence issues, reaching a mass residual of 0.2% of the total inflow after 40 to 100 iterations per time step for time steps of 0.01 s. Grid sensitivity studies have shown that non-uniform grids are necessary because of the sudden changes in flow cross section, and the flow simulations are insensitive to grid refinement for non-uniform grids with more than 300,000 cells. The best agreement between the experimentally-measured flow distributions between fillet spaces and those predicted by the simulation have been achieved for (effective) bulk viscosities between the laminar viscosity for water and ten times that value. This change in viscosity is not very large (less than an order of magnitude), given that effective turbulent viscosities are typically several orders of magnitude greater than laminar ones. This result is consistent with the transitional flows here. The effect of weights above the stack can reduce the degree of non-uniformity in air velocities through the stack, especially when thick weights are used, because the stack may then be separated from the eddy at the top of the plenum chamber. [source] Determination of Drying Characteristics and Effective Diffusivity for Sugar CubesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2004C. Akosman Abstract In this study, the drying characteristics of sugar cubes have been investigated. Drying experiments with sugar cubes were conducted in a laboratory-type tray dryer at temperatures ranging from 45 to 95,°C and different air velocities (0.43, 0.56, and 0.7,m/s). Drying rates increased with the increase in temperature and air velocity. At high temperatures, the moisture content of the solid reached equilibrium moisture value in short time periods. Experimental data were analyzed by using the analytical solution of the unsteady-state diffusion equation to determine the effective diffusivity in sugar cubes. [source] Development and experimental validation of a conceptual model for biotrickling filtration of H2SENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2003Seongyup Kim A dynamic model that describes the behavior of high-performance hydrogen sulfide (H2S)-degrading biotrickling filters for odor control was developed. The model attempts to accurately describe pollutant mass transfer in the biotrickling filter, i.e., external mass transfer resistances, and both direct gas-biofilm and gas-liquid-biofilm mass transfer were considered. In order to calibrate the model, an innovative differential biotrickling filter was constructed in which the effect of air velocity on the removal of H2S could be studied. Model outputs were compared with experimental data to determine the sensitivity of the system to selected parameters. At low H2S concentration, diffusion of H2S within the biofilm, and biofilm thickness were the major governing factors among nine considered model parameters. At higher H2S concentrations and lower air flow rates, external mass transfer played a very important role. This new finding, confirmed experimentally, has important implications, as it proves that the performance limit of H2S degrading biotrickling filters has not yet been reached. [source] A basic study on humidity recovery by using micro-porous media (Effects of thermal condition of fluids and geometrical condition of apparatus on transport performance)HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 8 2006Shixue Wang Abstract Using an experimental apparatus to examine the performance of heat and mass transfer between constant-temperature water and dry air through a porous plate having extremely small pores, the effects of the thermal conditions in the fluids and the geometric condition of the apparatus on moisture transport were measured. The effects of water temperature, thickness of the porous plate, and channel height of the flowing air on moisture transport are noticeable. However, the effect of air temperature in the channel inlet on moisture transport is slight. In addition, in order to evaluate the degree of air humidity absorption, a parameter called the moisture absorption rate was introduced. The moisture absorption rate was shown to decrease with increasing air velocity and varies only slightly for a plate thickness of 1 mm and decreases for a plate thickness of 3.5 mm with increasing water temperature. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(8): 568,581, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20133 [source] Exergetic performance assessment of a pilot-scale heat pump belt conveyor dryerINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2010Zafer Erbay Abstract In this study, olive leaves were dried in a pilot-scale heat pump (HP) belt conveyor dryer as a thin layer. Drying experiments were carried out at the drying air temperature range of 45,55°C with the drying air velocity range of 0.5,1.5,m,s,1. The performance of the system and the process was evaluated using exergy analysis method. The exergy loss and flow diagram (the so-called Grassmann diagram) of the dryer system was presented to give quantitative information regarding the proportion of the exergy input that is dissipated in the various system components. Effects of the drying air temperature and the velocity on the performance of the drying process were discussed. The actual coefficient of performance values were obtained to be 2.37 for the HP unit and 2.31 for the overall system, respectively. The most important component of the system for improving the efficiency was determined to be the compressor. Exergetic efficiencies of the drying of olive leaves were in the range of 67.45,81.95%. It was obtained that they increased as the drying air temperature decreased and the drying air velocity increased. Copyright © 2009 John Wiley & Sons, Ltd. [source] Exergetic evaluation of drying of laurel leaves in a vertical ground-source heat pump drying cabinetINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2007Ebru Hancioglu Kuzgunkaya Abstract This paper is concerned with the exergy analysis of the single layer drying process of laurel leaves in a ground-source heat pump drying cabinet, which was designed and constructed in the Solar Energy Institute, Ege University, Izmir, Turkey. The effects of drying air temperature on exergy losses, exergy efficiencies and exergetic improvement potential of the drying process are investigated. The results have indicated that exergy efficiencies of the dryer increase with rising the drying air temperature. Moreover, the laurel leaves are sufficiently dried at the temperatures ranging from 40 to 50°C with relative humidities varying from 16 to 19% and a drying air velocity of 0.5 m s,1 during the drying period of 9 h. The exergy efficiency values are obtained to range from 81.35 to 87.48% based on the inflow, outflow and loss of exergy, and 9.11 to 15.48% based on the product/fuel basis between the same drying air temperatures with a drying air mass flow rate of 0.12 kg s,1. Copyright © 2006 John Wiley & Sons, Ltd. [source] Effect of temperature and initial moisture content on sorption isotherms of banana dried by tunnel drierINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2008Zhengyong Yan Summary Sorption isotherms of intermediate moisture content (IMC) products are essential to predict shelf-life of packaged moisture-sensitive product by modelling moisture uptake during storage and distribution. The effect of temperature and initial moisture content (MC) of IMC banana on the relationship between MC and water activity were investigated. Raw bananas were dried in a tunnel dryer at 2% relative humidity (RH), 70 °C, and a 3.2 ± 0.2 m s,1 air velocity. Drying procedure was carried out a number of times until various IMC levels were obtained (5%, 14%, 22% and 33% db for banana). Sorption isotherms of bananas were determined at 10, 20, 30 and 40 °C. The initial MC of IMC banana had no significant effect on the relationship between MC and water activity according to statistical analysis. All the sorption curves were found to be Type II. BET, GAB, modified GAB, Oswin, Halsey and modified Freundlich models were fitted to the data and it was found that the best results were obtained with a modified Freundlich equation. A secondary modified Freundlich model was built accounting for the effect of aw and temperature on the sample MC. [source] Single-layer drying characteristics and colour kinetics of red chilliINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 11 2007Mohammed Ayub Hossain Summary Single-layer drying experiments were conducted under controlled conditions of temperature, relative humidity (RH) and air velocity to find out the effects of drying conditions and blanching on the drying rate and colour of Thai red chilli. Drying rate increased with an increase of drying air temperature and a decrease of RH. Air temperatures above 65 °C affected the colour of red chilli. Red chilli should be dried at an air velocity equal to or just above 0.50 m s,1. Above this value, the drying rate becomes independent of air velocity. RH and air velocity have no effect on the colour of red chilli. Faster drying rate and higher colour value was found for the blanched sample rather than the unblanched sample. The Newton and the Page equations were fitted to the experimental data. The Newton equation was found to describe the single-layer drying of red chilli better than the Page equation. [source] Assessment of airflow patterns inside six industrial beef carcass chillersINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2001Pierre-Sylvain Mirade Airflow patterns determine process efficiency in beef carcass chilling. An experimental study of air velocity in six industrial chillers (three batch and three continuous systems) afforded a diagnosis of their overall operation. However, the original experimental method did not provide an ideal chiller design: only configurations that were a priori more favourable for carcass chilling than others were identified. To complete the study, calculations were performed using computational fluid dynamics techniques. Applied to a continuous beef carcass chiller, this helped correct a dysfunction revealed in the experimental diagnosis, resulting in a marked lack of ventilation throughout about half the volume of the plant. [source] THIN-LAYER DRYING KINETICS OF SESAME HULLS UNDER FORCED CONVECTION AND OPEN SUN DRYINGJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2007MAJDI A. AL-MAHASNEH ABSTRACT Sesame hulls are a useful by-product of the sesame processing industry. The sesame hulls are produced at a high moisture content (68% wet basis) and need further drying to prevent deterioration. In this study, both open sun drying (OSD) and forced convection drying (FCD) at 42, 55, and 76C and 1.2 m/s air velocity were investigated. Six common thin-layer drying models were fitted to the experimental data. Several statistical parameters were used to evaluate the performance of thin-layer drying models, including r2, x2, root mean square error (RMSE) and residuals. Sesame hull drying was found to take place completely in the falling rate region. The modified Page model was found to describe OSD data well, while the Wang and Singh model was the best model for describing FCD. Effective diffusivity was found to be 1.89 × 10 - 8 m2/s and 7.36 × 10 - 10 to 1.20 × 10 - 9 m2/s for OSD and FCD, respectively. Activation energy was also found to be 12.95 kJ/mol for FCD. [source] TWO-PHASE MODELING AND THE QUALITY OF SOYBEAN SEEDS DRIED IN A COUNTER-CURRENT MOVING BED DRIERJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2004A.F. LACERDA ABSTRACT The purpose of the present work is to study the simultaneous heat and mass transfer between air and soybean seeds in a countercurrent moving bed dryer, based on the application of a two-phase model to the drying process. The numerical solution of the model is obtained by using a computational code based on backwards differential formulae. The experimental data of air humidity and temperature and of seed moisture content and temperature at the dryer outlet are compared to the simulated values, showing a good agreement. This work also analyzes the effect of the main process variables (drying air temperature, air relative humidity, air velocity and solids flow rate) on the soybean seeds quality during drying. Empirical equations fitted to the experimental data are proposed for predicting the soybean seed quality (germination, vigor and fissures) as a function of the investigated variables. [source] HEAT TRANSFER COEFFICIENT FOR COOKIE SHAPED OBJECTS IN A HOT AIR JET IMPINGEMENT OVENJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2001N. NITIN ABSTRACT Correlations for average heat transfer coefficient for cookie shaped objects in a hot air jet impingement oven were obtained using aluminum cookie models. The study was carried out in a pilot plant scale hot air jet impingement oven. The effects of individual cookie position, presence of surrounding cookies, air velocity, air temperature and rotation of the oven plate on average surface heat transfer coefficient were investigated. The value of the heat transfer coefficient ranged between 100,225 W/m2K and was found to be a strong function of jet air velocity. The impact of surrounding cookies on the heat transfer coefficient was more for smaller cookies, which had larger cookie-to-cookie spacing. [source] MATHEMATICAL MODELLING OF THIN-LAYER DRYING OF KIWIFRUIT SLICESJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2009M DOYMAZ ABSTRACT The effect of temperature on the drying kinetics of kiwifruit was investigated. The drying process was carried out at temperatures of 50, 55 and 60C, air velocity of 2.4 m/s and relative humidity between 10,25%. Drying time decreased considerably with increased air temperature. Drying process took place in the falling rate period. Twelve mathematical models available in the literature were fitted to the experimental data. The models were compared by four statistical parameters; i.e., determination of coefficient, mean relative percent error, reduced chi-square and root mean square error, and the best-fit model was selected. The modified Henderson and Pabis and Verma et al. models were given the best results in describing thin-layer drying of kiwifruits. The effective diffusivity of water during air-drying varied from 1.743 to 2.241 × 10,10 m2/s over the temperature range investigated, with activation energy equal to 22.48 kJ/mol. PRACTICAL APPLICATIONS Drying can be described as an industrial preservation method in which water content and activity of agricultural products are decreased by heated air to minimize biochemical, chemical and microbiological deterioration. Kiwifruit has a very short life because of softening and vitamin loss during cold storage. The use of drying prolongs the shelf-life of the kiwifruit, as the water content reduction slows down deterioration reactions. In this study, drying characteristics of kiwifruits were studied in a convectional hot-air dryer. The objectives of the present study were to determine experimentally the thin-layer drying characteristics and rehydration capacity of samples, and to fit the experimental data to 12 mathematical models available from the literature. [source] Modeling Cooking Time to Inactivate Salmonella in Chicken Leg Quarters Cooked in an Air,Steam Impingement OvenJOURNAL OF FOOD SCIENCE, Issue 5 2006Tareq M. Osaili ABSTRACT:, Inadequate cooking of poultry products may lead to human foodborne infections. The use of mathematical models that describe heat transfer during cooking of chicken leg quarters may help in developing safer food products and minimizing time for cooking. The objective of this study was to develop regression models that predict cooking time required to reach internal temperatures of 71.1, 73.9, 76.7, and 82.2 °C in chicken leg quarters. Samples that had different weights, thicknesses, and initial internal temperatures were cooked in an air,steam impingement oven at temperature of 232.2 °C, humidity of 60%, and air velocity of 1.4 m/min. A thermocouple probe (type K) connected with a data acquisition system was inserted into the coldest point of each chicken leg quarter. Samples were cooked until they reached an internal temperature higher than 82.2 °C. The collected data of each sample in the data acquisition system were used to develop regression models that depend on sample weight, thickness, and initial temperature in predicting cooking times. Sample weight, thickness, and initial internal temperature had significant effects on the cooking time. The results of these models would be helpful for ready-to-eat poultry processors to meet lethality performance standards, and ensuring the safety and quality of skin on, bone in chicken leg quarters cooked via air,steam impingement ovens. [source] Dehydration kinetics of red pepper (Capsicum annuum L var Jaranda)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2003N Sanjuán Abstract Shredded and whole red pepper samples were dehydrated in a laboratory drier with a through-flow air velocity of 0.5,m,s,1 at 50, 55, 60 and 70,°C. Shredded peppers dried faster than whole peppers. The drying behaviour of whole samples was characterised by a constant- and a falling-rate drying period, whilst that of shredded samples was characterised by a falling-rate drying period only. The mass transfer coefficient for whole samples during the constant-rate period was computed experimentally. The effect of temperature on the mass transfer coefficient was described by the Arrhenius model. The activation energy was 58,kJ,mol,1. In the falling-rate period the mass transfer was described by a diffusional model, and the effective diffusion coefficient at each temperature was determined. Diffusion coefficients were estimated to lie between 4.38,×,10,11 and 10.99,×,10,11,m2,s,1 for whole peppers and between 37.23,×,10,11 and 99.61,×,10,11,m2,s,1 for shredded peppers. The effect of temperature on the effective diffusion coefficient was described by the Arrhenius equation, with an activation energy of 44,kJ,mol,1 for whole peppers and 56,kJ,mol,1 for shredded peppers. © 2003 Society of Chemical Industry [source] Comparison of plume structures of carbon dioxide emitted from different mosquito trapsMEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2006Miriam F. Cooperband Abstract., A large field wind tunnel was used to compare four types of CO2 -baited mosquito traps. This study compared the plume structure and concentration of CO2 emitted by each trap, flow of suction into the trapping systems, flow of CO2 being released, trap shape and configuration, differences in visual appearance, and differences in temperature and humidity of emissions at the source of CO2 compared to ambient air. The structure of the CO2 plumes emitted by each trap differed considerably. All four plumes were turbulent, causing the concentration of CO2 within several metres of the source to attenuate to between 375 and 875 p.p.m. The Encephalitis Virus Surveillance (EVS) trap emitted concentrations of CO2 exceeding 20 000 p.p.m., the detection limits of our equipment, whereas the Mosquito Magnet® Freedom (MMF), Mosquito Magnet® Liberty (MML) and Mosquito Magnet® X (MMX) traps released CO2 at peaks of about 3500, 7200 and 8700 p.p.m., respectively. The MMX trap produced the greatest air velocity at both the suction inlet and CO2 outlet, followed by the MMF, MML and the EVS traps, respectively. [source] The effect of gravity on surface temperatures of plant leavesPLANT CELL & ENVIRONMENT, Issue 4 2003Y. KITAYA ABSTRACT A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 °C, a relative humidity of 18% and an irradiance of 260 W m,2. Mean leaf temperatures increased by 0.9,1.0 °C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 °C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 °C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s,1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection. [source] Identification and removal of above-ground spurious signals in GPR archaeological prospecting,ARCHAEOLOGICAL PROSPECTION, Issue 2 2005Luigia Nuzzo Abstract Ground-penetrating radar (GPR) is a shallow geophysical method increasingly used in archaeological prospecting to detect buried remains and to map the stratigraphy of the uppermost earth layers embodying the archaeological features. The GPR sections, however, can be contaminated by spurious correlated signals caused by above-ground obstacles (buildings, trees, fences, power lines) placed either in-line or off-line with respect to the profile (surface scattering). In the case study presented this problem is analysed for a 35,MHz GPR survey carried out for stratigraphical purposes in the archaeological site of the Roman Ships near Pisa (Italy). The investigation inside the archaeological excavation, when the level was about 5,m below the ground surface, produced a severe surface scattering problem caused by the iron sheet-piling protecting the excavation walls and bordering some of the partly excavated boats. An attempt to interpret the profiles was carried out in a zone where the relatively simple geometry of the metallic enclosure allowed understanding of the possible origin of spurious events, also thanks to the high density of profiles acquired along two orthogonal directions. Migration at the air velocity and geometrical considerations helped the identification of hyperbolic and slightly slanted features as surface scattering phenomena from different sides of the iron sheet-piling. A simple but original subtraction procedure was successful for the attenuation of some of the spurious reflections. After this partial removal, other spurious signals could be recognized more easily as well as two weak subhorizontal reflections of probable stratigraphical meaning. Subsequently, filtering procedures based on f-k and Radon transform methods were tried to further reduce the spurious signals, thus enhancing the visibility of the interesting reflections. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of seeding sludge type and hydrodynamic shear force on the aerobic sludge granulation in sequencing batch airlift reactorsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009K. Y. Koh Abstract Two sequencing batch airlift reactors (SBARs) were operated simultaneously for two separate runs. In the first run, two different types of seeding sludge were cultivated in two separate reactors under the same superficial air velocity (SAV). In the second run, the same seeding sludge was cultivated in both reactors but under different SAV, i.e. 1.2 and 3.6 cm s,1. Both runs were carried out for a period of about 20 days, during which the chemical oxygen demand (COD) removal efficiency and morphology of sludge were examined. Batch tests using sodium acetate as the main carbon source were conducted to investigate the COD removal efficiency, and the morphologies of sludge were examined under light microscopy. Results showed that the COD removal efficiency improved with cultivation time. Morphological study showed that all cultivated sludge lost their filamentous species after a few days of cultivation, leaving behind communities of loosely packed pellet-like groups. Although the SAV recommended by other researchers was applied to the SBAR, granulation did not take place at the end of both experimental runs. It was suspected that the failure for aerobic sludge to granulate under the selected operating strategies and reactor configuration was partly due to the intrinsic traits of the sludge microbial community. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Determination of Drying Characteristics and Effective Diffusivity for Sugar CubesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2004C. Akosman Abstract In this study, the drying characteristics of sugar cubes have been investigated. Drying experiments with sugar cubes were conducted in a laboratory-type tray dryer at temperatures ranging from 45 to 95,°C and different air velocities (0.43, 0.56, and 0.7,m/s). Drying rates increased with the increase in temperature and air velocity. At high temperatures, the moisture content of the solid reached equilibrium moisture value in short time periods. Experimental data were analyzed by using the analytical solution of the unsteady-state diffusion equation to determine the effective diffusivity in sugar cubes. [source] Infants sleeping outdoors in a northern winter climate: skin temperature and duration of sleepACTA PAEDIATRICA, Issue 9 2010Marjo Tourula Abstract Aim:, The aim of the study is to describe the relationships among thermal environment, skin temperatures and infants' daytime outdoor sleep duration in northern winter conditions. Methods:, This study is a cross-over observational study. Skin temperatures of three-month-old infants were recorded from seven skin sites continuously throughout outdoor (n = 34) and indoor sleep (n = 33) in the families' homes. The duration of the sleep was observed, and temperature and the air velocity of the environment were recorded. Results:, Skin temperatures increased towards the end of indoor sleeping, whereas they decreased during outdoor sleeping. The cooling rate of mean skin temperature (Tsk) increased in lower outdoor temperatures (rs = 0.628, p < 0.001) in spite of increased clothing. On some occasions, cold extremities were observed, suggesting slight deviations from thermoneutrality. Sleep time was 92 min longer in outdoors than in indoors. However, outdoor sleep duration was shortened when the cooling rate of Tsk increased (rs = 0.611, p < 0.001). Conclusion:, The longest sleep was recorded outdoors when the cooling rate of Tsk was minimal. Restriction of movements by clothing probably increases the length of sleep, and a cold environment makes swaddling possible without overheating. A decrease in ambient temperature increased the cooling rate, suggesting that the cold protection of the clothing compensated only partly for the increased heat loss. [source] | |||||||||||||||||||||||||||||||