Application of REA-method to a convective drying of apple rings at ambient temperature

2018 ◽  
Author(s):  
D. Bulegenov ◽  
Sayara Saliyeva ◽  
A. Sekerbayeva ◽  
Sergey Spotar
Keyword(s):  
Ambient Temperature ◽  
Ambient Air ◽  
Reaction Engineering ◽  
Convective Drying ◽  
Energy Curve ◽  
Drying Rate ◽  
Transfer Coefficients ◽  
Ambient Temperature Condition ◽  
Reference Measurements ◽  
Normal Processing

This study focuses on the convective drying of apple rings without any extra-heating of the processing ambient air. The lumped reaction engineering approach (REA) model has been employed to determine the rate of drying for the apple rings under forced convection considered as a normal processing regime. The algorithm implies determination the activation energy curve from the accurate ‘reference’ measurements of the drying rate under natural convection conditions. The required for the model implementation mass transfer coefficients for the apple ring samples under natural and forced conditions were obtained in the series of customized experiments. The study does extend the application of REA for the limiting simplest case of convective drying of thick samples under ambient temperature condition."

Utilisation of the REA-method to a Convective Drying of Apple Rings at Ambient Temperature

2020 ◽  
Vol 16 (5-6) ◽  
Author(s):  
Sergey Spotar ◽  
Sayara Saliyeva ◽  
Alibek Kopbayev ◽  
Temirlan Shildebayev
Keyword(s):  
Mass Transfer ◽  
Ambient Temperature ◽  
Reaction Engineering ◽  
Convective Drying ◽  
Energy Curve ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Series Of Experiments ◽  
Reference Measurements ◽  
Normal Processing

AbstractThis study focuses on the convective drying of apple rings by air at ambient temperature. The lumped reaction engineering approach (REA) model has been employed to determine the rate of drying for apple rings under forced convection considered as a normal processing regime. The algorithm implies origination of the activation energy curve from accurate ‘reference’ measurements of the drying rate under natural convection conditions. Mass transfer coefficients for the apple ring samples required for the model implementation were obtained in a series of experiments under natural and forced conditions. These were compared to the values of mass transfer coefficients obtained from numerical simulation using COMSOL Multiphysics® software. The study extends the application of REA for the limiting simplest case of convective drying of thick samples under ambient temperature conditions.

CATFISH DRYING (Clarias Batraclus) USING ‘TEKO BERSAYAP’ SOLAR DRYER

2012 ◽  
Vol 2 (1) ◽  
pp. 14-20
Author(s):  
Yuwana Yuwana
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Ambient Temperature ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Time ◽  
Ambient Relative Humidity ◽  
Solar Dryer

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.

scholarly journals Changes in ambient temperature increase hospital outpatient visits for allergic rhinitis in Xinxiang, China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jianhui Gao ◽  
Mengxue Lu ◽  
Yinzhen Sun ◽  
Jingyao Wang ◽  
Zhen An ◽  
...  
Keyword(s):  
Allergic Rhinitis ◽  
Ambient Temperature ◽  
Positive Association ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Hospital Outpatient ◽  
Distributed Lag ◽  
Outpatient Visits ◽  
Daily Data ◽  
The Relationship

Abstract Background The effect of ambient temperature on allergic rhinitis (AR) remains unclear. Accordingly, this study aimed to explore the relationship between ambient temperature and the risk of AR outpatients in Xinxiang, China. Method Daily data of outpatients for AR, meteorological conditions, and ambient air pollution in Xinxiang, China were collected from 2015 to 2018. The lag-exposure-response relationship between daily mean temperature and the number of hospital outpatient visits for AR was analyzed by distributed lag non-linear model (DLNM). Humidity, long-time trends, day of the week, public holidays, and air pollutants including sulfur dioxide (SO2), and nitrogen dioxide (NO2) were controlled as covariates simultaneously. Results A total of 14,965 AR outpatient records were collected. The relationship between ambient temperature and AR outpatients was generally M-shaped. There was a higher risk of AR outpatient when the temperature was 1.6–9.3 °C, at a lag of 0–7 days. Additionally, the positive association became significant when the temperature rose to 23.5–28.5 °C, at lag 0–3 days. The effects were strongest at the 25th (7 °C) percentile, at lag of 0–7 days (RR: 1.32, 95% confidence intervals (CI): 1.05–1.67), and at the 75th (25 °C) percentile at a lag of 0–3 days (RR: 1.15, 95% CI: 1.02–1.29), respectively. Furthermore, men were more sensitive to temperature changes than women, and the younger groups appeared to be more influenced. Conclusions Both mild cold and mild hot temperatures may significantly increase the risk of AR outpatients in Xinxiang, China. These findings could have important public health implications for the occurrence and prevention of AR.

An Experimental Study of Heat and Mass Transfer During Drying of Packed Beds

1992 ◽  
Vol 114 (3) ◽  
pp. 727-734 ◽  
Author(s):  
W. C. Lee ◽  
O. A. Plumb ◽  
L. Gong
Keyword(s):  
Mass Transfer ◽  
Experimental Study ◽  
Glass Beads ◽  
Drying Rate ◽  
Packed Beds ◽  
Transfer Coefficients ◽  
Model Predictions ◽  
Drying Models ◽  
Surface Saturation ◽  
Drying Conditions

An experimental study has been conducted to provide a data base for drying packed beds of granular, nonhygroscopic materials. Experimental results for drying rate, saturation distribution, temperature distribution, and surface saturation are reported for drying glass beads under carefully documented drying conditions. Capillary pressure for both imbibition and drainage was measured for the glass beads, whose size ranged from 65 μm to 450 μm. The drying results demonstrate that, contrary to available model predictions, porous materials do not necessarily exhibit saturation gradients that always increase with distance from the drying surface. Under certain conditions the capillary potential is sufficient to create an internal drying front. The measurements of surface saturation are the first to be reported. They are utilized to speculate on the reasons for the failure of drying models to compare well with experiment without adjusting the convective heat or mass transfer coefficients.

Auxiliary Heating of the Hands during Cold Exposure and Manual Performance

1971 ◽  
Vol 13 (5) ◽  
pp. 457-465 ◽  
Author(s):  
John M. Lockhart ◽  
Harold O. Kiess
Keyword(s):  
Ambient Temperature ◽  
Cold Exposure ◽  
Auxiliary Heating ◽  
Knot Tying ◽  
Performance Tasks ◽  
Impaired Performance ◽  
Ambient Temperature Condition ◽  
Significant Performance ◽  
Manual Tasks ◽  
Manual Performance

Twenty subjects performed five manual tasks barehanded during exposure to a 60°-F ambient temperature control condition, a 0°-F condition, and three ambient temperature conditions of 20°, 0°, and −20° F, in which auxiliary heat was applied to the hands. The tasks consisted of the Purdue Pegboard assembly, block-stringing, Minnesota Rate of Manipulation placing, knot-tying, and screw-tightening tasks and were performed after exposure durations of 0, 60, 120, and 180 min. Exposure to the 0°-F condition without auxiliary heat resulted in significant performance decrements on all tasks. The application of auxiliary heat to the hands resulted in the avoidance or alleviation of impaired performance during cold exposure depending upon the task, ambient temperature condition, and duration of exposure. The differential effects of auxiliary heat during cold exposure across manual performance tasks were related to the effects of auxiliary heat on hand skin temperature. These effects are discussed in terms of differential hand and finger dexterity, strength, and speed of movement requirements across tasks.

Performance Improvement of Gas Turbine Power Plant by Intake Air Passive Cooling Using Phase Change Material Based Heat Exchanger

2017 ◽  
Author(s):  
Devendra Dandotiya ◽  
Nitin D. Banker
Keyword(s):  
Heat Exchanger ◽  
Ambient Temperature ◽  
Phase Change ◽  
Gas Turbine ◽  
Air Temperature ◽  
Power Output ◽  
Ambient Air ◽  
Passive Cooling ◽  
Air Intake ◽  
Change Material

The power output of a gas turbine plant decreases with the increase in ambient temperature. Moreover, the ambient temperature fluctuates about 15–20°C in a day. Hence, cooling of intake air makes a noticeable improvement to the gas turbine performance. In this regard, various active cooling techniques such as vapor compression refrigeration, vapor absorption refrigeration, vapor adsorption refrigeration and evaporative cooling are applied for the cooling of intake air. This paper presents a new passive cooling technique where the intake air temperature is reduced by incorporating phase change material (PCM) based heat exchanger parallel to conventional air intake line. During the daytime, the air is passed through the PCM which has melting temperature lower than the peak ambient temperature. This will reduce the ambient air temperature before taking to the compressor. Once the PCM melts completely, the required ambient air would be drawn from the ambient through conventional air intake arrangement. During the night, when there is lower ambient temperature, PCM converts from liquid to solid. The selected PCM has a melting temperature less than the peak ambient temperature and higher than the minimum ambient temperature. It is observed from the numerical modeling of the PCM that about four hours are required for the melting of PCM and within this time, the intake air can also be cooled by 5°C. The thermodynamic analysis of the results showed about 5.2% and 5.2% improvement in net power output and thermal efficiency, respectively for four hours at an ambient temperature of 45°C.

scholarly journals Characterization of Fly Ash and Metakaolin Blend Geopolymers under Ambient Temperature Condition

2019 ◽  
Vol 551 ◽  
pp. 012086
Author(s):  
Khairunnisa Zulkifly ◽  
Heah Cheng Yong ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Liew Yun Ming ◽  
Andrei Victor Sandu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Ambient Temperature ◽  
Ambient Temperature Condition

scholarly journals Heat Transfer Characteristics of Aluminum Sputtered Fabrics

2018 ◽  
Vol 13 (3) ◽  
pp. 155892501801300 ◽  
Author(s):  
Hye Ree Han ◽  
Yaewon Park ◽  
Changsang Yun ◽  
Chung Hee Park
Keyword(s):  
Heat Transfer ◽  
Heat Dissipation ◽  
Ambient Air ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Hot Plate ◽  
Multilayer Systems ◽  
Heat Transfer Coefficients ◽  
Transfer Characteristics ◽  
Shape Memory Polyurethane

Al was sputtered onto four substrates: nylon, polyester, cotton/polyester, and shape memory polyurethane nanoweb, and the heat-transfer characteristics of the resultant materials were investigated by surface temperature measurements. The thickness of the Al layer increased linearly with sputtering time. The heat-transfer mechanisms of the multilayer systems in terms of conduction, convection, and radiation were investigated under steady-state conditions using a hot plate as a heat source in contact with Al-sputtered fabrics. The Al-sputtered fabric was placed on the hot plate, which was maintained at 35°C, and exposed to open air, which was maintained at 15°C. The temperatures of the air-facing surfaces of hot plate-Al-fabric-air (i.e., Al-phase-down) and hot plate-fabric-Al-air (i.e., Al-phase-up) systems were used to investigate the heat-transfer mechanism. It was found that heat dissipation to ambient air was much higher for the Al-phase-up system than for the Al-phase-down system. Heat-transfer coefficients of the Al surfaces were calculated and found to increase with the thickness of the Al layer. Furthermore, different conductive thermal resistances were observed for different fabrics prepared with the same Al-sputtering time. Consequently, differences in their thicknesses pore sizes, and thermal conductivities were suggested to have significant effects on their heat-transfer properties.

scholarly journals Description of Cumbeba (Tacinga inamoena) Waste Drying at Different Temperatures Using Diffusion Models

Foods ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1818
Author(s):  
João P. L. Ferreira ◽  
Wilton P. Silva ◽  
Alexandre J. M. Queiroz ◽  
Rossana M. F. Figueirêdo ◽  
Josivanda P. Gomes ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Effective Mass ◽  
Sample Surface ◽  
Fruit Production ◽  
Diffusion Models ◽  
Convective Drying ◽  
Convective Mass Transfer ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Drying Conditions

One approach to improve sustainable agro-industrial fruit production is to add value to the waste generated in pulp extraction. The processing of cumbeba (Tacinga inamoena) fruits generates a significant amount of waste, which is discarded without further application but can be a source of bioactive compounds, among other nutrients. Among the simplest and most inexpensive forms of processing, convective drying appears as the first option for the commercial utilization of fruit derivatives, but it is essential to understand the properties of mass transfer for the appropriate choice of drying conditions. In this study, cumbeba waste was dried at four temperatures (50, 60, 70 and 80 °C). Three diffusion models were fitted to the experimental data of the different drying conditions. Two boundary conditions on the sample surface were considered: equilibrium condition and convective condition. The simulations were performed simultaneously with the estimation of effective mass diffusivity coefficients (Def) and convective mass transfer coefficients (h). The validation of the models was verified by the agreement between the theoretical prediction (simulation) and the experimental results. The results showed that, for the best model, the effective mass diffusivities were 2.9285 × 10−9, 4.1695 × 10−9, 8.1395 × 10−9 and 1.2754 × 10−8 m2/s, while the convective mass transfer coefficients were 6.4362 × 10−7, 8.7273 × 10−7, 8.9445 × 10−7 and 1.0912 × 10−6 m/s. The coefficients of determination were greater than 0.995 and the chi-squares were lower than 2.2826 × 10−2 for all simulations of the experiments.

Heat and Mass Transfer Analysis of a Pot-in-Pot Refrigerator Using Reynolds Flow Model

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Ramendra Pandey ◽  
Bala Pesala
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Ambient Temperature ◽  
Heat And Mass Transfer ◽  
Heat Load ◽  
Radiation Heat Transfer ◽  
Ambient Air ◽  
Total Heat ◽  
Maximum Efficiency ◽  
Radiation Heat

Heat and mass transfer analysis of evaporative cooling process in a pot-in-pot cooling system is done based on Reynolds flow hypotheses. The model proposed herein assumes that the heat transfer due to natural convection is coupled with an imaginary ambient air mass flow rate (gAo) which is an essential assumption in order to arrive at the solution for the rate of water evaporation. Effect of several parameters on the pot-in-pot system performance has been studied. The equations are iteratively solved and detailed results are presented to evaluate the cooling performance with respect to various parameters: ambient temperature, relative humidity (RH), pot height, pot radius, total heat load, thermal and hydraulic conductivity, and radiation heat transfer. It was found that pot height, pot radius, total heat load, and radiation heat transfer play a critical role in the performance of the system. The model predicts that at an ambient temperature of 50 °C and RH of 40%, the system achieves a maximum efficiency of 73.44% resulting in a temperature difference of nearly 20 °C. Similarly, for a temperature of 30 °C and RH of 80%, the system efficiency was minimum at 14.79%, thereby verifying the usual concept that the pot-in-pot system is best suited for hot and dry ambient conditions.

Sign in / Sign up

Export Citation Format

Share Document