New Approach for Analyzing Solar Collectors Subjected to Unequal Front/Rear Ambient Temperatures: The Equivalent Ambient Temperature Concept, Part 2: Validation and Implications for Design

2002 ◽  
Vol 124 (3) ◽  
pp. 268-275 ◽  
Author(s):  
Kam T. K. Ho ◽  
Dennis L. Loveday
Keyword(s):  
Ambient Temperature ◽  
Experimental Work ◽  
Solar Collector ◽  
Solar Simulator ◽  
New Approach ◽  
Ambient Temperatures ◽  
Solar Air Collector ◽  
Different Temperatures ◽  
Traditional Approaches ◽  
Temperature Concept

An approach based on a new conceptual temperature termed the “equivalent ambient temperature” has been introduced for analyzing solar collector thermal performances when the environments to the front and rear of a collector are at different temperatures. Using a specially-designed solar simulator, experimental work is presented which validates the new approach as applied to a wall-integrated covered profiled metal solar air collector. Using both the new and traditional approaches, collector thermal performances are predicted to reveal the practical conditions for which use of the new approach is warranted. The latter findings will be of importance to designers. Performance characteristics for this collector geometry are also presented for use by designers.

New Approach for Analyzing Solar Collectors Subjected to Unequal Front/Rear Ambient Temperatures: The Equivalent Ambient Temperature Concept, Part 1: Modeling

2002 ◽  
Vol 124 (3) ◽  
pp. 262-267 ◽  
Author(s):  
Kam T. K. Ho ◽  
Dennis L. Loveday
Keyword(s):  
Energy Balance ◽  
Ambient Temperature ◽  
Solar Collector ◽  
Heat Removal ◽  
Efficiency Factor ◽  
Standard Analysis ◽  
New Approach ◽  
Ambient Temperatures ◽  
Overall Heat Loss Coefficient ◽  
Temperature Concept

Standard analyses of solar collector thermal performance are based upon an energy balance in which the environments adjoining the front and rear of the collector are assumed to be at the same temperature. This assumption is inappropriate for some collector designs, particularly building-integrated collectors. An approach for analyzing such situations is presented based upon a new conceptual temperature termed the “equivalent ambient temperature.” The concept is explained, the new temperature is defined, and the approach is applied to a typical collector geometry. The approach retains the convenience of the standard analysis while accounting for the unequal front/rear ambient temperatures and permits collector characterization in terms of the conventional parameters: plate efficiency factor, F′; heat removal factor, FR; overall heat loss coefficient, UL, and effective transmittance–absorptance product, ταe.

Computational Investigation of Diesel Combustion and Soot Formation With a Phenomenological Soot Model Under Different Temperatures in a Constant Volume Chamber

2014 ◽  
Author(s):  
Zhichao Zhao ◽  
Chia-Fon Lee ◽  
Yawei Chi ◽  
Jingping Liu
Keyword(s):  
Ambient Temperature ◽  
Soot Formation ◽  
Constant Volume ◽  
Diffusion Combustion ◽  
Soot Emission ◽  
Ambient Temperatures ◽  
Constant Volume Chamber ◽  
Constant Volume Combustion Chamber ◽  
Different Temperatures ◽  
Soot Model

The previous nine-step phenomenological soot model was revised by including the oxidation effect on soot number density. Using KIVA-3V Release 2 code coupled with this revised phenomenological soot model, multi-dimensional computational fluid dynamics (CFD) simulations of diesel spray combustion in a constant volume chamber was conducted to investigate the combustion physics and soot emission characteristics. Meanwhile, experiments were conducted in an optical constant volume combustion chamber under different ambient temperatures (800, 900, 1000 K), from which the combustion characteristics and soot distributions were obtained for validation. The results indicate that ignition retards with the decrease of ambient temperature, which results in more air-fuel mixing controlled diffusion combustion at high ambient temperature, and more premixed combustion at low ambient temperature. The corresponding soot formation and distribution shows that the soot emission is strongly related to the local equivalence ratio, which leads to lower soot emission in the lower initial temperature case with more homogeneous mixture. Compared to previous nine-step model, the revised model predicted lower soot number and bigger soot particles size.

Influence of ambient temperature on the Ektachem DT60 results for total bilirubin and total protein.

1987 ◽  
Vol 33 (1) ◽  
pp. 138-139 ◽  
Author(s):  
B C Dujardin ◽  
J C Hafkenscheid ◽  
A F Roijers ◽  
M Schoorl ◽  
J van der Ven-Jongekrijg
Keyword(s):  
Clinical Trial ◽  
Ambient Temperature ◽  
Total Protein ◽  
Room Temperature ◽  
Total Bilirubin ◽  
Fixed Temperature ◽  
Calibration Period ◽  
Ambient Temperatures ◽  
Different Temperatures ◽  
Protein Assays

Abstract We evaluated the Kodak Ektachem DT60 analyzer with the DTE module in a two-month clinical trial before its introduction in the Netherlands. At ambient temperatures that differed from that at which the DT60 was calibrated, aberrant behavior for total bilirubin and total protein assays was observed. At subnormal temperatures the former gave higher results than expected, and the latter, lower results. We found a similar effect for total protein determined by the manual biuret reaction at different temperatures, when results were calculated from calibration at a fixed temperature. Total bilirubin assayed by the manual diazobilirubin method showed no such effect. Although the DT60 analyzer is equipped with a temperature-regulated incubator, we conclude that the manufactures's recommended room temperature range for these assays should be narrowed and the three-month calibration period adjusted according to external circumstances.

Effect of temperature on structure, morphology and crystallinity of PVDF nanofibers via electrospinning

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Fenglin Huang ◽  
Qufu Wei ◽  
Jiaxi Wang ◽  
Yibing Cai ◽  
Yubo Huang
Keyword(s):  
Thermal Properties ◽  
Ambient Temperature ◽  
Vinylidene Fluoride ◽  
Effect Of Temperature ◽  
Scanning Calorimetry ◽  
Ambient Temperatures ◽  
Force Microscopy ◽  
Poly Vinylidene Fluoride ◽  
Different Temperatures ◽  
Surface Morphologies

Abstract Influence of temperature on morphology, structure and crystallinity of Poly (vinylidene fluoride) (PVDF) nanofibers was investigated in this study. The Wehilmy technique and viscosity testing apparatus were used to evaluate the surface tension and viscosity of electrospun solutions at various ambient temperatures. Surface morphologies and diameters of nanofibers were examined by Field-emission Scanning Electron Microscopy (FE-SEM) and atomic force microscopy (AFM). It was found that the surface morphologies were obviously affected by ambient temperature. This dependence was attributed to the change of the properties of Poly (vinylidence fluoride) solutions with temperature. The thermal properties and crystal structures of the PVDF nanofibers electrospun at different temperatures were also studied by differential scanning calorimetry (DSC), and Xray diffraction (XRD). The results revealed that the crystallinity and thermal properties were improved by increasing the ambient temperature during electrospinning

scholarly journals Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2286
Author(s):  
Jan Kominek ◽  
Martin Zachar ◽  
Michal Guzej ◽  
Erik Bartuli ◽  
Petr Kotrbacek
Keyword(s):  
Heat Transfer ◽  
Ambient Temperature ◽  
Convective Heat ◽  
Heat Dissipation ◽  
High Surface ◽  
Heat Sinks ◽  
Fourth Power ◽  
Molding Process ◽  
Ambient Temperatures ◽  
University Of Technology

Miniaturization of electronic devices leads to new heat dissipation challenges and traditional cooling methods need to be replaced by new better ones. Polymer heat sinks may, thanks to their unique properties, replace standardly used heat sink materials in certain applications, especially in applications with high ambient temperature. Polymers natively dispose of high surface emissivity in comparison with glossy metals. This high emissivity allows a larger amount of heat to be dissipated to the ambient with the fourth power of its absolute surface temperature. This paper shows the change in radiative and convective heat transfer from polymer heat sinks used in different ambient temperatures. Furthermore, the observed polymer heat sinks have differently oriented graphite filler caused by their molding process differences, therefore their thermal conductivity anisotropies and overall cooling efficiencies also differ. Furthermore, it is also shown that a high radiative heat transfer leads to minimizing these cooling efficiency differences between these polymer heat sinks of the same geometry. The measurements were conducted at HEATLAB, Brno University of Technology.

scholarly journals Influence of Solar Concentrator in the Form of Luminescent PMMA on the Performance of a Silicon Cell

2021 ◽  
Vol 13 (4) ◽  
pp. 2086
Author(s):  
Bartłomiej Milewicz ◽  
Magdalena Bogacka ◽  
Krzysztof Pikoń
Keyword(s):  
Solar Cell ◽  
Social Awareness ◽  
Single System ◽  
Solar Concentrator ◽  
Solar Simulator ◽  
Laboratory Environment ◽  
Energy Technologies ◽  
Acrylic Glass ◽  
Different Temperatures ◽  
Silicon Cell

The methods of production of electricity from renewable sources are currently highly researched topics. The reason for this is growing social awareness regarding the environmental impact of traditional energy technologies. The main aim of this study is to describe the results of using silicon cell technology and dye concentrator in a single system. The experiment presented in the paper was conducted in a laboratory environment using a dye concentrator in the form of tinted and luminescent acrylic glass (polymethyl methacrylate, PMMA). The experiment was conducted using a few measurement calibrations for the described system, such as different temperatures of the researched silicon cell or different intensity of illuminance from a solar simulator. The results of the experiment showed increase in the performance of the solar cell between 0.05% and 1.42% depending on the pigments used in the concentrator. The highest results were achieved for luminescent red PMMA and on average the improvement was 1.21%. This shows us the potential for the implementation of a luminescent dye concentrator in solar electric technology.

scholarly journals Insufficient Stability of Clavulanic Acid in Widely Used Child-Appropriate Formulations

Antibiotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 225
Author(s):  
Ines Mack ◽  
Mike Sharland ◽  
Janneke M. Brussee ◽  
Sophia Rehm ◽  
Katharina Rentsch ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Clavulanic Acid ◽  
Storage Conditions ◽  
Essential Medicines ◽  
Active Components ◽  
Middle Income ◽  
Ambient Temperatures ◽  
Essential Medicines List ◽  
Dispersible Tablets ◽  
The Stability

Amoxicillin-clavulanic acid (AMC) belongs to the WHO Essential Medicines List for children, but for optimal antimicrobial effectiveness, reconstituted dry powder suspensions need to be stored in a refrigerated environment. Many patients in low- and middle-income countries who are sold AMC suspensions would be expected not to keep to the specified storage conditions. We aimed to assess the stability of both ingredients in liquid formulations and dispersible tablets, combined with nationally representative data on access to appropriate storage. Degradation of amoxicillin (AMX) and clavulanic-acid (CLA) was measured in suspensions and dispersible tablets commercially available in Switzerland at different ambient temperatures (8 °C vs. 28 °C over 7 days, and 23 °C vs. 28 °C over 24 h, respectively). Data on access to refrigeration and electricity were assessed from the USAID-funded Demographic and Health Survey program. In suspensions, CLA degraded to a maximum of 12.9% (95% CI −55.7%, +29.9%) at 8°C and 72.3% (95% CI −82.8%, −61.8%) at a 28 °C ambient temperature during an observation period of 7 days. Dispersible tablets were observed during 24 h and CLA degraded to 15.4% (95% CI −51.9%, +21.2%) at 23 °C and 21.7% (−28.2%, −15.1%) at a 28 °C ambient temperature. There is relevant degradation of CLA in suspensions during a 7-day course. To overcome the stability challenges for all active components, durable child-appropriate formulations are needed. Until then, prescribers of AMC suspensions or pharmacists who sell the drug need to create awareness for the importance of proper storage conditions regarding effectiveness of both antibiotics and this recommendation should be reflected in the WHO Essential Medicines List for children.

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

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