The physical factors involved in the drying of sultana grapes

1957 ◽  
Vol 8 (5) ◽  
pp. 444 ◽  
Author(s):  
RJL Martin ◽  
GL Stott
Keyword(s):  
Free Water ◽  
Total Loss ◽  
Drying Rate ◽  
Physical Factors ◽  
Initial Water Content ◽  
Initial Water ◽  
Loss Of Weight ◽  
Original Weight ◽  
Drying Rates ◽  
Parenchymal Cells

The various physical factors involved in the drying of sultana grapes have been determined from measurements of drying rate under definite conditions of temperature, humidity, and air flow, in a specially constructed oven. Ninety-five per cent. of weight lost is water, 2 per cent. is carbon dioxide produced at an almost constant rate during drying, and 3 per cent. unassigned loss. Drying occurs in three distinct stages: (1) the grape retains its regular ellipsoidal shape by an elastic contraction of the skin; (2) the skin commences to wrinkle in the range of 20-50 per cent, loss in original weight; (3) the drying rate decreases markedly, beginning when approximately 95 per cent. of total loss of weight has occurred and when probably all the free water has been removed from the system. For each of these stages there is a linear relation between time and log [c / (c – w) 1, where c is the total loss in weight on complete drying (approximately initial water content), and w is the loss in weight at time t. A drying constant has been calculated from this logarithmic function for the initial stage of drying, and has been used for determining the mechanism of drying. Water movements through the parenchymal cells are fast compared with those through the skin. Since various dipping treatments give different drying rates there is no rate-controlling diffusion through the stationary air layer a t the grape surface. The drying rate is controlled by the diffusion of water through the waxy cuticle, and is inversely proportional to the amount of cuticle present as determined by extraction with chloroform. The elastic contraction of the skin causes an increase in the thickness of the cuticle which reduces the permeability. The heat required for the evaporation of water and for heating the grape to the equilibrium drying temperature is transferred from the surroundings to the grape. The rate of drying increases rapidly with rise in temperature owing to the vapour pressure of water and the permeability of the cuticle increasing with the temperature.

Effects of differential drying rates on viability retention of recalcitrant seeds of Ekebergia capensis

1998 ◽  
Vol 8 (4) ◽  
pp. 463-471 ◽  
Author(s):  
N. W. Pammenter ◽  
Valerie Greggains ◽  
J. I. Kioko ◽  
J. Wesley-Smith ◽  
Patricia Berjak ◽  
...  
Keyword(s):  
Water Content ◽  
Exponential Function ◽  
Time Course ◽  
Drying Rate ◽  
Recalcitrant Seeds ◽  
Tissue Water ◽  
Initial Water ◽  
Viability Loss ◽  
Drying Rates ◽  
Water Contents

AbstractThe drying rate of whole seeds of Ekebergia capensis (Meliaceae) was shown to influence the response to desiccation, with rapidly dried seeds surviving to lower water contents. Short-term rapid drying (to water contents higher than those leading to viability loss) actually increased the rate of germination. The form of the time course of decline of axis water content varied with drying rate; slow drying could be described by an exponential function, whereas with rapid drying initial water loss was faster than predicted by an exponential function. These observations suggest that slow drying brought about homogeneous dehydration and that the rapid drying was uneven across the tissue. This raised the possibility that the different responses to dehydration were a function of different distributions of water in the axis tissue under the two drying regimes. However, ultrastructural observations indicated that different deleterious processes may be occurring under the different drying treatments. It was tentatively concluded that a major cause of viability loss in slowly dried material was likely to be a consequence of aqueous-based processes leading to considerable membrane degradation. Uneven distribution of tissue water could not be rejected as a contributory cause of the survival of rapidly dried seeds to low bulk water contents. The differential response to dehydration at different drying rates implies that it is not possible to determine a ‘critical water content’ for viability loss by recalcitrant seeds.

The Influence of Dehumidifying Condition on Expansive Soil Engineering Properties

2012 ◽  
Vol 594-597 ◽  
pp. 487-492
Author(s):  
Xiong Wei Li ◽  
Ai Jun Wang ◽  
Guo Zhong Dai
Keyword(s):  
Shear Strength ◽  
Relative Humidity ◽  
Water Content ◽  
Expansive Soil ◽  
Expansion Ratio ◽  
Soil Samples ◽  
Engineering Properties ◽  
Drying Rate ◽  
Initial Water Content ◽  
Initial Water

The expansive soil behaviour of expansive deformation and shear strength is deeply influenced by humidity condition. Different soil drying rate was set with constant temperature and different relative humidity. When saturated soil samples was dried to the different predetermined water content, the expansion ratio test with the upper load was made. It is shown that in the condition of high relative humidity, the expansion ratio is high. The smaller initial water content and upper load may lead to a larger swelling deformation. When soil samples with different initial water content was fully expanded, the consolidated direct shear tests were made. It is shown that the smaller drying rate leads to the greater shear strength after full expansion. What’s more, the upper load may improve the soil shear strength.

scholarly journals Rainfall threshold for hillslope outflow: an emergent property of flow pathway connectivity

2006 ◽  
Vol 3 (5) ◽  
pp. 2923-2961 ◽  
Author(s):  
P. Lehmann ◽  
C. Hinz ◽  
G. McGrath ◽  
H.-J. Tromp-van Meerveld ◽  
J. J. McDonnell
Keyword(s):  
Percolation Theory ◽  
Water Saturation ◽  
Soil Depth ◽  
Free Water ◽  
Rainfall Threshold ◽  
Rainfall Amount ◽  
Model Parameters ◽  
Initial Water Content ◽  
Linear Processes ◽  
Initial Water

Abstract. Nonlinear relations between rain input and hillslope outflow are common observations in hillslope hydrology field studies. In this paper we use percolation theory to model the threshold relationship between rainfall amount and outflow and show that this nonlinear relationship arises from simple linear processes at the smaller scale. When the rainfall amount exceeds a threshold value, the underlying elements become connected and water flows out of the base of the hillslope. The percolation approach shows how random variations in storage capacity and connectivity at the small spatial scale cause a threshold relationship between rainstorm amount and hillslope outflow. As a test case, we applied percolation theory to the well characterized experimental hillslope at the Panola Mountain Research Watershed. Analyzing the measured rainstorm events and the subsurface stormflow with percolation theory, we could determine the effect of bedrock permeability, spatial distribution of soil properties and initial water content within the hillslope. Our results indicate that the measured variation in the relationship between rainstorm amount and subsurface flow is dominated by the initial moisture deficit, the loss of free water to the bedrock, the limited size of the system and by the connectivity due to macropores. The values of the model parameters were in agreement with measured values of soil depth distribution and water saturation.

scholarly journals Penentuan Konstanta Laju Pengeringan Coconut Chips

2021 ◽  
Vol 7 (1) ◽  
pp. 39-49
Author(s):  
Hary Kurniawan ◽  
Sukmawaty Sukmawaty ◽  
Ansar Ansar ◽  
Kurniawan Yuniarto ◽  
Murad Murad ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Rate Constant ◽  
Rate Constants ◽  
Arrhenius Equation ◽  
Drying Rate ◽  
Initial Water Content ◽  
Thermogravimetric Method ◽  
Initial Water

This study aims to determine the drying rate constant of coconut chips using an oven. Coconut chips drying is carried out at drying temperatures of 50 ° C, 60 ° C and 70 ° C. Drying coconut chips has been conducted at an initial water content of 40-50% wb until it reached ± 10% wb. The change of moisture content was measured every 15 minutes, and the measurement of the water content was determined by the thermogravimetric method. Newton's model was used in determining the observation drying rate constant. Furthermore, the observation drying rate constant was applied to predict the drying rate constant as a function of temperature using the Arrhenius equation. The results showed that the predicted drying rate constants ranged from 0.0090 - 0.0130 minute-1. 

scholarly journals Researching the change in the weight of split oak firewood due to different drying methods

2021 ◽  
Vol 1208 (1) ◽  
pp. 012023
Author(s):  
Amina Gačo
Keyword(s):  
Room Temperature ◽  
Average Weight ◽  
Drying Methods ◽  
Initial Water Content ◽  
Initial Weight ◽  
Average Amount ◽  
Initial Amount ◽  
Initial Water ◽  
Original Weight ◽  
Air Circulation

Abstract In this paper, the influences of stacking methods and drying places of split oak firewood in winter conditions (Quercus cerris) have been experimentally and theoretically investigated, due to the great importance of use in heating with such wood. The research was conducted on a sample of 48 pieces of logs with bark made of freshly cut oak. The logs were obtained by mechanized technology with the help of grafting by a hydraulic splitter and a chainsaw. Each log was measured for a research length of 0.30 m, marked with numbers 1-24. On each log, the weight was measured on a scale of 5 kg with an accuracy of 0.5 grams. Drying of logs was performed in two places. The first drying place was in outdoor conditions, sheltered from the snow and ventilated. The second place was indoors, at approximately constant room temperature. The logs were stacked in a crossed way for better air circulation. They were dried between 15/12/2020 and 15/02/2021, a total of 62 days. The average initial weight of logs dried in the facility was 1130.3 g, in the dried state the average weight was 952.87 g, which represented 84.3% of the original weight. The average initial weight of logs dried in outdoor conditions was 1192.125 g, in the dried state 1076.37 g, which represented 90.29% of the original weight. The average initial water content in the logs dried in the facility was 37.9%, in the dried state it was 27.5%. For logs dried in outdoor conditions, the average initial amount of water was 36.6%, in the dried state the average amount of water was 31.2%.

scholarly journals Kajian Proses Pengeringan Pinang Muda (Areca catechu L) Menggunakan Bahan Bakar Biomassa Kayu : Studi Kasus PT. Areca Agro Aceh

2020 ◽  
Vol 4 (4) ◽  
pp. 522-531
Author(s):  
Cut Nazila Fitri ◽  
Indera Sakti Nasution ◽  
Raida Agustina
Keyword(s):  
Water Content ◽  
Biomass Fuel ◽  
Drying Rate ◽  
Initial Water Content ◽  
Areca Nut ◽  
Wood Biomass ◽  
Initial Water ◽  
Areca Catechu ◽  
Final Water Content ◽  
Air Flow Velocity

Abstrak. Pengeringan pinang muda menggunakan bahan bakar biomassa kayu dapat dilakukan dengan cara pengovenan. Pengeringan dilakukan sebanyak 3 kali pengulangan pada suhu 60oC, perhitungan masa pinang diukur tiap 3 jam untuk 24 jam pertama, tiap 6 jam untuk hari ke-2 sampai sampai massa bahan konstan. Parameter penelitian untuk mengetahui pinang kering berdasarkan perubahan bobot bahan dan kadar air meliputi laju pengeringan, kecepatan aliran udara, kelembaban udara, suhu dan perubahan berat bahan.Hasil penelitian pada PT. Areca Agro Aceh dalam proses pengeringan pinang muda kering dengan menggunakan bahan bakar biomassa kayu menghasilkan rata-rata kelembaban udara sebesar 56% dengan kecepatan aliran udara rata-rata sebesar 2,22 m/s. Untuk mendapatkan berat pinang muda kering yang konstan, pengeringan ulangan 1 dan ulangan 2 membutuhkan waktu sampai 90 jam sedangkan ulangan 3 membutuhkan waktu pengeringan sampai 96 jam dengan ulangan 1 kadar air awal pinang muda adalah 74,4%. Perubahan mulai terjadi pada jam ke 24 sampai jam ke 90 dengan kadar air akhir pinang muda adalah 22,4% sedangkan pada ulangan 2 kadar air awal pinang muda adalah 74,0% selama 90 jam pengeringan menghasilkan kadar akhir sebesar 21,1%. Pengeringan pinang muda pada ulangan 3 kadar air awalnya sebesar 74,2% menghasilkan kadar air akhir sebesar 21,8% selama 96 jam pengeringan. Laju pengeringan rata-rata selama proses pengeringan sebesar 0,04 bk/jam. Peningkatan laju pengeringan terjadi pada jam ke 21. Study of Batel Nut (Areca catechu L) Drying Process Using Wood Biomass Fuel: A Case Study of PT. Areca Agro AcehAbstract. Drying young areca nut using wood biomass fuel can be done by covenant. Drying is done 3 times repetition at a temperature of 60oC, calculation of areca nut mass is measured every 3 hours for the first 24 hours, every 6 hours for the 2nd day until the mass of material is constant. Research parameters to determine the dry areca nut based on changes in material weight and moisture content include drying rate, air flow velocity, air humidity, temperature and material weight change.The results of research at PT. Areca Agro Aceh in the process of drying areca nut dry using wood biomass fuel produces an average air humidity of 56% with an average air flow velocity of 2.22 m / s. To get a constant weight of dry young areca nut, drying repetition 1 and repetition 2 takes up to 90 hours while repetition 3 requires drying time up to 96 hours with repetition 1 The initial water content of young areca nut is 74.4%. Changes began to occur at the 24th hour to the 90th hour with the final water content of young areca nut being 22.4% while in Repeat 2 the initial water content of the areca nut was 74.0% for 90 hours of drying resulting in a final content of 21.1%. Drying young areca nut on replicate 3, the initial water content of 74.2% produced a final water content of 21.8% for 96 hours of drying. The average drying rate during the drying process is 0.04 bk / hour. Increased drying rate occurs at 21 hours.

scholarly journals Analytical solutions of water suction and drying processes vs. experiments

2020 ◽  
Vol 172 ◽  
pp. 04009
Author(s):  
Peter Matiasovsky ◽  
Peter Mihalka
Keyword(s):  
Water Absorption ◽  
Building Materials ◽  
Drying Rate ◽  
Initial Water Content ◽  
Initial Water ◽  
Water Absorption Coefficient ◽  
Capillary Suction ◽  
Calculation Results ◽  
Important Correlation ◽  
Analytical Expressions

The set of 25 inorganic porous building materials was put through the cumulative water inflow and drying tests in laboratory conditions. Besides these experiments the parameters, including pore structure parameters of the tested materials have been determined. The characteristics of the capillary suction induced water absorption – the water absorption coefficient, and drying – the initial constant drying rate, were compared with their analytical expressions. The results of this analysis show the measure of particular material parameters and boundary conditions significance for the coincidence of experimental and calculation results. At the drying an important correlation between experimentally obtained initial water content and drying rate was observed.

scholarly journals Rainfall threshold for hillslope outflow: an emergent property of flow pathway connectivity

2007 ◽  
Vol 11 (2) ◽  
pp. 1047-1063 ◽  
Author(s):  
P. Lehmann ◽  
C. Hinz ◽  
G. McGrath ◽  
H. J. Tromp-van Meerveld ◽  
J. J. McDonnell
Keyword(s):  
Percolation Theory ◽  
Water Saturation ◽  
Soil Depth ◽  
Free Water ◽  
Rainfall Threshold ◽  
Rainfall Amount ◽  
Model Parameters ◽  
Initial Water Content ◽  
Linear Processes ◽  
Initial Water

Abstract. Nonlinear relations between rain input and hillslope outflow are common observations in hillslope hydrology field studies. In this paper we use percolation theory to model the threshold relationship between rainfall amount and outflow and show that this nonlinear relationship may arise from simple linear processes at the smaller scale. When the rainfall amount exceeds a threshold value, the underlying elements become connected and water flows out of the base of the hillslope. The percolation approach shows how random variations in storage capacity and connectivity at the small spatial scale cause a threshold relationship between rainstorm amount and hillslope outflow. As a test case, we applied percolation theory to the well characterized experimental hillslope at the Panola Mountain Research Watershed. Analysing the measured rainstorm events and the subsurface stormflow with percolation theory, we could determine the effect of bedrock permeability, spatial distribution of soil properties and initial water content within the hillslope. The measured variation in the relationship between rainstorm amount and subsurface flow could be reproduced by modelling the initial moisture deficit, the loss of free water to the bedrock, the limited size of the system and the connectivity that is a function of bedrock topography and existence of macropores. The values of the model parameters were in agreement with measured values of soil depth distribution and water saturation.

Influence of initial water content and strain rate on remolded yield stress in marine clay

2021 ◽  
pp. 1-8
Author(s):  
Xiaobing Li ◽  
Jianpeng Chen ◽  
Xiuqing Hu ◽  
Hongtao Fu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Water Content ◽  
Yield Stress ◽  
Initial Water Content ◽  
Marine Clay ◽  
Initial Water

scholarly journals Application of the Calorimetric Methods to the Characteristics of Seeds from Olives

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 90
Author(s):  
Andrzej Bryś ◽  
Joanna Bryś ◽  
Marko Obranović ◽  
Dubravka Škevin ◽  
Szymon Głowacki ◽  
...  
Keyword(s):  
Olive Oil ◽  
Water Content ◽  
Cooling System ◽  
Waste Product ◽  
Normal Pressure ◽  
Ash Content ◽  
Initial Water Content ◽  
Scanning Calorimetry ◽  
Initial Water

The olive oil industry represents an important productive sector in the Mediterranean basin countries. Olive stone is an essential by-product generated in the olive oil extraction industries and it represents roughly 10% by weight of the olive fruit. The seeds of pickled olives are also a significant waste product. In the present study, we have investigated the possibility of the use of differential scanning calorimetry for the thermal characterization of seeds from green and black pickled olives from Croatia. The differential scanning calorimeter (DSC) with a normal pressure cell equipped with a cooling system was used to determine the thermal properties of seeds from olives. The following analyses were also performed: the determination of calorific values in a pressure bomb calorimeter, the determination of initial water content, the determination of changes of water content during drying at the temperatures of 30 °C, 50 °C and 80 °C, the determination of a percentage content of seeds mass to the mass of the whole olives, and the determination of ash content. Seeds from olives are characterized by very good parameters as a biomass. The analyzed olive seeds were characterized by low water content, low ash content, and a relatively high caloric value.

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