Moisture Absorption and Diffusion Characterization of Molding Compound

2005 ◽  
Vol 127 (4) ◽  
pp. 460-465 ◽  
Author(s):  
Xu Chen ◽  
Shufeng Zhao ◽  
Linda Zhai
Keyword(s):  
Relative Humidity ◽  
Moisture Absorption ◽  
Saturated Vapor ◽  
Ambient Air ◽  
Second Phase ◽  
Fick’S Law ◽  
Moisture Concentration ◽  
Molding Compound ◽  
Fick's Law ◽  
Temperature And Humidity

The moisture absorption experiments of two kinds of molding compound are conducted. The diffusion at low temperature and humidity observes the Fick’s Law, but it does not strictly obey at higher temperature and humidity. The phenomena can be attributed to the occurrence of the second phase, and the Fick’s Law can be modified by diffusion coefficient varying with the moisture concentration. The predicted value by the modified Fick’s Law agrees with the test data. At certain temperature, the saturated moisture content of molding compound is proportional to the relative humidity, and the proportional factor is the product of solubility and saturated vapor pressure. The solubility is a physical characteristic, which has no relations with the relative humidity of ambient air.

Experimental Study on Hygroscopicity of Rapeseed (Brassica Napus)

2012 ◽  
Vol 479-481 ◽  
pp. 2275-2278
Author(s):  
Ming Jin Yang ◽  
Wu Ming Xu ◽  
Tian Tang ◽  
Ling Yang ◽  
Feng Liu
Keyword(s):  
Experimental Study ◽  
Brassica Napus ◽  
Relative Humidity ◽  
Moisture Absorption ◽  
Early Period ◽  
Critical Relative Humidity ◽  
Temperature And Humidity ◽  
Higher Temperature

The hygroscopicity property of the rapeseed at different temperature and humidity was experimental studied in this paper. Tested results show that: the moisture absorption rates increase with the increase of relative humidity at the early period of absorption, and higher temperature leads to earlier reach of moisture equilibrium; the critical relative humidity(CRH) increases with the increase of temperature; the optional relative humidity for safety storage of rapeseed should be controlled less than 60%.

OBSERVATIONS ON THE PERMEABILITY OF HYGROSCOPIC MATERIALS TO WATER VAPOUR: I. OBSERVATIONS AT RELATIVE HUMIDITIES LESS THAN 75%

1940 ◽  
Vol 18a (6) ◽  
pp. 105-121 ◽  
Author(s):  
J. D. Babbitt
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Vapour Pressure ◽  
Fick’S Law ◽  
Moisture Movement ◽  
Fick's Law ◽  
Vapour Pressure Difference ◽  
Moisture Content Gradient ◽  
Vapour Pressure Gradient

It is pointed out that experimental work has shown that for the transpiration of moisture through hygroscopic materials two distinct regions of relative humidity can be distinguished: (i) A region below some value between 70 and 80% where the moisture movement is proportional to the vapour pressure difference, and (ii) a region of high relative humidity where the moisture movement is not directly proportional to the vapour pressure. A theory is advanced that these two regions correspond to the two conditions in which water may be present in a hygroscopic material: (i) the water may be molecularly adsorbed, that is to say, the water is bound by the affinity of the molecules of water for those of the solid on which it is adsorbed; (ii) the water may be held in small fissures in the sub-microscopic structure of the sorbing material by capillary forces. The mechanism by which the moisture will move through the material would be different in the two cases and would result in the distinction between regions of high and of low relative humidity.A short discussion is given of Fick's law showing the form in which it might be expected to apply in the two cases. Measurements are given for fibreboards showing that below 75% relative humidity the resistance of the board to moisture transpiration is proportional to the thickness. The moisture content gradients through fibreboard samples have been determined. The diffusance through a board in which the moisture content gradient is opposed to the vapour pressure gradient shows that the latter is the important factor, and the determination of the moisture content gradient indicates that at these low humidities Fick's law is applicable.

Development of microcontroller-based data logger for real-time monitoring of drying and storage of food grains

2021 ◽  
Vol 45 (01) ◽  
pp. 1-10
Author(s):  
Pramod P. Aradwad ◽  
T. V. Arun Kumar ◽  
Abhinav Dubey ◽  
Indra Mani
Keyword(s):  
Relative Humidity ◽  
Real Time ◽  
Ambient Air ◽  
Real Time Monitoring ◽  
Data Logger ◽  
Storage Structure ◽  
Control Factors ◽  
Food Grains ◽  
Temperature And Humidity ◽  
And Storage

Food grains are harvested at higher moisture content to avoid losses during harvesting. Temperature and relative humidity are the key control factors of drying and storage operations for maintaining and enhancing the quality of food. Real-time monitoring and management of these parameters improve the level of post-harvest processing and reduce losses. An effort has been made to develop a data logger for real-time monitoring of the drying and storage environment. It consists of different modules such as precision integrated temperature and relative humidity sensor DHT22, LCD, SD Card, motor control driver, and RTC 3231 for real-time monitoring and data recording of temperature and humidity. An open-source-based software program was developed to integrate all modules in one platform to operate sequentially. Developed data logger tested in a 0.5-tonne grain storage structure and 100 kg capacity solar-powered air-inflated dryer. The temperature of drying air ranged between 29.8 and 38.2°C compared to ambient air temperature ranging from 25.7 and 34°C. Moisture reduction from 22% to 14% (w.b.) was completed in 7.5-9 hours in the developed dryer compared to 11-12.8 hours in sun drying. Variation of temperature and humidity inside double-wall insulated silo is less as compared to the single wall and triple-layer plastic storage structure. The salient features of this developed system are costefficient, portable, robust, and fast use and perform satisfactorily under different conditions.

scholarly journals Experimental study of evaporation of droplets of water ethanol solution at high relative air humidity

2021 ◽  
Vol 2057 (1) ◽  
pp. 012059
Author(s):  
A N Sterlyagov ◽  
M I Nizovtsev ◽  
V N Letushko
Keyword(s):  
Relative Humidity ◽  
Ethyl Alcohol ◽  
High Speed ◽  
Moisture Absorption ◽  
Water Solution ◽  
Ambient Air ◽  
Droplet Surface ◽  
Ethanol Solution ◽  
High Relative Humidity ◽  
Air Humidity

Abstract A change in the temperature of suspended droplets of a water solution of ethanol, evaporating at high relative humidity, is experimentally investigated using high-speed microphotography and infrared thermography. The data obtained for ethyl alcohol droplets show a significant dependence of the surface temperature of evaporating droplets on relative humidity of the ambient air. It should be noted that at high relative humidity, a significantly smaller decrease in the temperature of droplet surface than at low humidity was observed during evaporation. This relates to the processes of moisture absorption and condensation on the surface of an evaporating droplet of ethyl alcohol at high air humidity, accompanied by the release of heat.

Influence of Non-Equilibrium Fluid Properties During Fogging on Intake Duct and Compressor Characteristics

2017 ◽  
Author(s):  
Christoph Günther ◽  
Franz Joos
Keyword(s):  
Relative Humidity ◽  
Gas Turbine ◽  
Thermophysical Properties ◽  
Ambient Air ◽  
Compressor Stage ◽  
Compression Process ◽  
Fluid Properties ◽  
Temperature And Pressure ◽  
Gas Turbine Compressor ◽  
Non Equilibrium

This study reports on numerically calculated thermophysical properties of air passing through a gas turbine compressor after passage through an intake duct affected by wet compression. Case of reference is unaffected ambient air (referenced to as dry scenario) passing through intake duct and compressor. Furthermore, ambient air cooled down by (overspray) fogging (referenced to as wet scenarios) was considered. Acceleration at the end of intake duct causing reduction of static temperature and pressure results in supersaturated fluid properties at inlet to gas turbine compressor. These supersaturated fluid properties are non-equilibrium with saturation level above relative humidity of φ = 1. Entrance of supersaturated fluid into gas turbine compressor can result in condensation within first compressor stage. At the same time delayed impact of evaporative cooling influences compression process.

Slow rehydration improves the recovery of dried bacterial populations

1992 ◽  
Vol 38 (6) ◽  
pp. 520-525 ◽  
Author(s):  
J. W. Kosanke ◽  
R. M. Osburn ◽  
G. I. Shuppe ◽  
R. S. Smith
Keyword(s):  
Relative Humidity ◽  
Rhizobium Leguminosarum ◽  
Moisture Absorption ◽  
Rhizobium Meliloti ◽  
Bacterial Populations ◽  
Bulk Powder ◽  
Alfalfa Seed ◽  
Powder Samples ◽  
Cellular Stresses ◽  
Rhizobium Leguminosarum Biovar Trifolii

Slow rehydration of bacteria from dried inoculant formulations provided higher viable counts than did rapid rehydration. Estimates were higher when clay and peat powder formulations of Rhizobium meliloti, Rhizobium leguminosarum biovar trifolii, and Pseudomonas putida, with water activities between 0.280 and 0.650, were slowly rehydrated to water activities of approximately 0.992 before continuing the dilution plating sequence. Rhizobium meliloti populations averaged 6.8 × 108 cfu/g and 1328 cfu/alfalfa seed greater when slowly rehydrated from bulk powder and preinoculated seeds, respectively. Bulk powder samples were slowly rehydrated to 0.992 water activity by the gradual addition of diluent, followed by a 10-min period for moisture equilibration. Preinoculated seed samples were placed in an environmental chamber at 24 °C with relative humidity greater than 80% for 1 h to allow moisture absorption. "Upshock," osmotic cellular stresses that occur during rehydration, was reduced when dried microbial formulations were slowly rehydrated and equilibrated before becoming fully hydrated in the dilution plating sequence. These procedures may also be applicable when estimating total viable bacterial populations from dried soil or other dry formulations. Key words: rehydration procedure, microbial rehydration, desiccation, Rhizobium, Pseudomonas.

Effect Of Moisture On The Physical Properties Of Polyimide Films

1991 ◽  
Vol 227 ◽  
Author(s):  
Rajeevi Subramanian ◽  
Michael T. Pottiger ◽  
Jacqueline H. Morris ◽  
Joseph P. Curilla
Keyword(s):  
Dielectric Constant ◽  
Steady State ◽  
Electrical Properties ◽  
Relative Humidity ◽  
Quartz Crystal ◽  
Moisture Absorption ◽  
Relative Dielectric Constant ◽  
Moisture Uptake ◽  
Polyimide Films ◽  
Effect Of Moisture

ABSTRACTMoisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.

Multi-lamellar organization of fully deuterated lipid extracts of yeast membranes

2014 ◽  
Vol 70 (12) ◽  
pp. 3167-3176 ◽  
Author(s):  
Yuri Gerelli ◽  
Alexis de Ghellinck ◽  
Juliette Jouhet ◽  
Valérie Laux ◽  
Michael Haertlein ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Neutron Diffraction ◽  
Structural Complexity ◽  
Structural Features ◽  
Metabolic Effects ◽  
Growth Media ◽  
Small Momentum Transfer ◽  
Lipid Species ◽  
Two Samples ◽  
Temperature And Humidity

Neutron scattering studies on mimetic biomembranes are currently limited by the low availability of deuterated unsaturated lipid species. In the present work, results from the first neutron diffraction experiments on fully deuterated lipid extracts from the yeastPichia pastorisare presented. The structural features of these fully deuterated lipid stacks are compared with those of their hydrogenous analogues and with other similar synthetic systems. The influence of temperature and humidity on the samples has been investigated by means of small momentum-transfer neutron diffraction. All of the lipid extracts investigated self-assemble into multi-lamellar stacks having different structural periodicities; the stacking distances are affected by temperature and humidity without altering the basic underlying arrangement. At high relative humidity the deuterated and hydrogenous samples are similar in their multi-lamellar arrangement, being characterized by two main periodicities of ∼75 and ∼110 Å reflecting the presence of a large number of polar phospholipid molecules. Larger differences are found at lower relative humidity, where hydrogenous lipids are characterized by a larger single lamellar structure than that observed in the deuterated samples. In both cases the heterogeneity in composition is reflected in a wide structural complexity. The different behaviour upon dehydration can be related to compositional differences in the molecular composition of the two samples, which is attributed to metabolic effects related to the use of perdeuterated growth media.

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