• International Journal of Advanced Culture Technology
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• 제3권2호
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• pp.138-143
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• 2015

This paper was aimed to study the drying kinetics of coffee and to investigate the thin-layer drying kinetics of coffee by using a convective air dryer. The coffee was dried for the temperatures of 40, 50 and $60^{\circ}C$ with relative humidity in the range of 14-25% the airflow rate fixed at 1 m/s. According to the experiment result, the drying rate curve showed that drying process took place only in the falling rate period. Seven thin layer drying models (Newton, Page, Henderson and Pabis, Logarithmic, Wang and Singh, Two terms, Modified Henderson and Pabis) were fitted to the experimental moisture content data. The Two-trem model was found to be a better model for describing the characteristics of coffee for the temperatures of 40, 50 and $60^{\circ}C$. The effective moisture diffusivity of coffee increased when the drying temperature increased. The value was in the range of $4.5028{\times}10^{-11}$ to $6.4803{\times}10^{-11}m^2/s$.

• International Journal of Computer Science & Network Security
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• 제24권6호
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• pp.77-82
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• 2024

The Smart home energy consumption represents much of the total energy consumed in advanced countries. For this reason, the main objectif of this paper is to study the energy consumption profile by day for each home appliances: controllable appliances for example Washing machine, Tumble dryer and Air conditioning and uncontrollable appliances for example TV, PC, Lighting, Refrigerator and Electric heater. In this paper, we start with presentation of a smart home energy management systems. Next, we present the modeling and simulation of controllable appliances and uncontrollable appliances. Finally, concludes this paper with some prospects. The modeling and the simulation of a Smart home appliances is based on MATLAB/Simulink software.

• Particle and aerosol research
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• 제18권3호
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• pp.79-86
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• 2022

Many commercial air purifiers currently have deployed granular activated carbon (GAC) filters for removing volatile organic compounds in the indoor air. GACs are generally used to remove gaseous contaminants in the air through adsorption by the inner surfaces of pores. In addition, airborne particles can be also filtered by the surface adsorption of the GACs, which can improve the life-time of the particulate filters. In this study, the filtration efficiency of GACs to ultrafine particles through surface adsorption was investigated at different volume flow rates by deploying a continuous particle filtration system. The polydisperse sodium chloride (NaCl) particles were generated by a set of an atomizer and a diffusion dryer, and then mixed with particle-free air at different volume flow rates. The penetration of ultrafine particles and pressure drop for each experimental condition were measured to figure out the effect of the volume flow rate on the surface adsoprtion of the GACs to particles, ~ 2 mm. The particle filtration efficiency of the GACs decreased as the volume flow rate increased from 4 to 14 lpm. However, the 5 times thicker GAC filter layer decreased the penetration of ultraparticles than a preious study. The filtration efficiency of the single granule was also higher than the previous result in the literature with smaller granule filter materials.

• Journal of Korean Society of Environmental Engineers
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• 제34권12호
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• pp.821-827
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• 2012

Air drying is a technology to dry sludge at the ejector and multi cyclone as intaking and blowing air from outside. So, this technology has a weak point that operating fluctuation is large according to an outside conditions as well as energy consumption is also large due to open loop structure. This is to develop the closed-loop air drying system to be built the dehumidifier consisted of condenser, cooler and compressor at rear side of separator of air dryer, as a way to solve some problem. Air is circulation by the method of blowing-drying-dehumidifying-blowing within this system. It is analyzed that an air circulated at closed-loop air drying equipment contains the energy of 50% more compared with open-loop air drying and is operated regularly because of quality maintenance of air to dry sludge. And also it is analyzed that the cost of drying sludge of 1 ton by closed-loop air drying equipment is lower about 35% than conventional equipment. Therefore, this is evaluated by useful drying technology to face an unexpected climatic conditions due to regular operation as well as low energy consumption.

• Korean Journal of Food Science and Technology
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• 제14권4호
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• pp.342-349
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• 1982

Filefish muscle in the form of thin plate $(5{\times}10{\times}0.4\;cm)$ was dried in a forced air dryer at $47.5^{\circ}C$ to study the relation between dehydration mechanism and water activity. The dryer was designed in such a way that the temperature, relative humidity and velocity of air could be controlled. The whole dehydration process of the filefish muscle was divided into two different drying rate periods, constant and falling rate period. During the constant drying rate period, the drying rate was proportional to the square root of air velocity under the conditions of constant temperature and relative humidity of air. The falling rate period was further divided into two different falling drying rate periods, first and second falling rate period. The first falling rate period was an unsaturated surface drying period caused by partial unsaturation of the drying surface with capillary condensed free water diffused from the internal part of the filefish muscle. At this stage he drying rate was mainly dependent on the relative humidity at constant air temperature, and case-hardening phenomenon started at the end of this stage. The moisture content and the water activity at which the second falling rate period started were not constant, because the drying rate of the first falling rate period was strongly dependent on the air humidity. The second falling rate period was again divided into two drying rate periods, former and latter period. The drying rates of both of these periods were independent on the external air humidity. During the former period of the second falling rate period, the dehydration was proceeded by diffusion and vaporization of capillary condensed free water in filefish muscle. The diffusion coefficient of water was $2.89{\times}10^{-10}m^2/sec\;at\;47.5^{\circ}C$. At this stage, the case-herdening continued until the water activity reduced to 0.7. The latter period of the second falling rate period started at the water activity of 0.45. The dedydration was proceeded by diffusion and vaporization of bound water, which adsorbed in multimolecular layers, through the hardened drying surface. The number of molecular layers was 4, and the diffusion coefficient of water during this stage was $4.38{\times}10^{-11}m^2/sec\;at\;47.5^{\circ}C$.

• Journal of agriculture & life science
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• 제53권5호
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• pp.137-143
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• 2019

To manufacturing of solid fuel by reuse of the wastes, the drying unit which have 500 kg/hr of drying capacity was developed and experimentally evaluate the performance. The spinach grown in Nam-hae island were used for the experiments and investigated of the heated-air drying characteristics as the inlet amount of raw materials, raw material stirring status, conveying type and drying time. The drying air heated by the energy derived from the steam which is supplied from the incineration plant. The moisture contents of raw materials were measured 85.65%. The inlet flow rate of drying air made a difference as the depth of the raw materials loaded on the drying unit and temperature has showed 108~144℃. The drying speed of the mixed drying more than doubled as that of non mixed drying under the same drying type, inlet amount, drying time and drying air temperature. In each experiment, the drying capacity have showed over 500 kg/hr. A drying efficiency of the ratio of drying consumption energy to input energy was 33.46%, lower than the average of 57.76% for the 157 conventional dryers. Because developed dryer must have a drying time of less than one hour, it is considered that the dry efficiency has been reduced due to the loss of wind volume during drying. If waste heat from incineration plant is used as a direct heat source, the dry air temperature is expected to be at least 160℃, greatly improving the drying capacity.

• Journal of Biosystems Engineering
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• 제11권1호
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• pp.52-63
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• 1986

This study was performed to find out drying characteristics and develop drying model for the design of an efficient dryer or drying system of red peper. The basic model which describes drying phenomenon of red pepper was firstly established, and drying tests were conducted at 14-different drying conditions. In this test, the effects of drying air temperature and relative humidity on the rate of drying were undertaken. Finally, a new drying model based on these experimental results was developed to describe the drying characteristics of red pepper. The results from this study may be summarized as follows. 1. Drying constant of the basic model established from Lewis' experimental model and diffusion equation was theoretically deduced as a function of moisture content and inner-temperature of red pepper. 2. From the results of drying tests, drying air temperature was found to have the greatest effect on the rate of drying. However, the effect of temperature was small for the condition of high relative humidity, and for low temperature, the effect of relative humidity was found to be large even though the range of relative humidity was low. 3. Modified Henderson equation was found to be better than Chung equation as the EMC model for the estimation of the equilibrium moisture content of red Pepper. 4. Constant-rate drying period did not exist in the red pepper drying test. And falling-rate drying period was divided into three distinct phases. Drying rate was dependent on the moisture content, the inner-temperature of red pepper and the change of physical property due to drying. 5. Drying constant increased with decrease of free moisture content, but it decreased at the end of the drying period. Also, drying constant was dependent on the drying air temperature and relative humidity. 6. The new drying model developed in this study was found to be most suitable in describing the drying characteristics of red pepper. Therefore, it may be concluded that drying time could be accurately estimated by the new drying model.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제16권4호
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• pp.349-354
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• 1983

A study on the color changes of fish meat during drying was conducted using fishes with different lipid contents, such as Alaska pollack as lean fish, conger eel as white fleshed fatty fish, and sardine as dark fleshed fatty fish. The fish meat was dried in a forced air dryer for 20 hours at 40, 55 and $70^{\circ}C$, The air velocity was 0.4 m/sec and the relative humidity of air was controlled to a constant value in the range of 10 to $50\%$. The color changes were evaluated with the brown color densities developed by lipid oxidation and Maillard reaction. The predominant reaction for the brown color developed during drying was lipid oxidation, The more the lipid content of fish and the higher the drying temperature were, the more violent the oxidative reaction of Lipid was. The rate of lipid oxidation during drying at 40 and $55^{\circ}C$ was affected by the relative humidity of air and was the slowest around $30\%$. But no remarkable influence of relative humidity on the rate of lipid oxidation could be confirmed during drying at $70^{\circ}C$. It seemed that the rate of lipid oxidation at higher temperature was more sensitive to the temperature than the relative humidity of air. Maillard reaction showed not so significant influence on the color changes of fish meat during drying. The rate of reaction was increased with increasing relative humidity of air in the range of 10 to $50\%$.

• Applied Biological Chemistry
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• 제34권3호
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• pp.258-261
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• 1991

In order to establish the optimum drying temperature of the heated air blast-grain circulation dryer, a 2 ton scale of paddy was used in this experiment. The temperatures of heated air used were 45, 50, 55, 60, 65 and $70^{\circ}C$. Moisture content of the paddy was reduced to 15% from 24% by drying. The higher air temperature, the shorter drying time and the less fuel consumed. The portion of cracked kernels was found to be low as $3{\sim}10%\;at\;40{\sim}55^{\circ}C$, but was very high to $28{\sim}30%\;at\;60{\sim}70^{\circ}C$. The germination percent was very high as 98 and 93% at 40 and $45^{\circ}C$, but it was decreased to 86 and 30% at 50 and $70^{\circ}C$, respectively. The recovery yield of milled rice from paddy was decreased by 1.76, 2.63 and 7.52% at 60, 65 and $70^{\circ}C$, respectively, compared with 75.86% as drying at $40^{\circ}C$. The higher heated air temperature, the less head rice of milled rice was recovered, and the decreased ratio was increased $60^{\circ}C$. The higher heated air temperature, the less alkali disintergation value and gel consistency of milled rice and the more water up take, expanded vlume, total solid in residual liquid and intensity of starch iodine blue value of residual liquid, and those tendency was found clear from $60^{\circ}C$ temperature of heated air.

• Preventive Nutrition and Food Science
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• 제13권1호
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• pp.28-32
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• 2008

Water vapor sorption by sodium alginate-based films may result in swelling and conformational changes in the molecular structure and affecting the water vapor barrier properties. Sodium alginate film specimens were dried in a vacuum freeze dryer and their moisture content was determined by an air-oven method. The water vapor absorption was determined at two different levels of water activities (0.727 and 0.995) and at three temperatures (10, 20, and $30^{\circ}C$), and kinetics were analyzed using a simple empirical model. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs 1/t. It was found that water vapor absorption kinetics of sodium alginate films were accurately described by a simple empirical model. The rate of water vapor sorption increased with increase in temperature and it showed temperature dependency following the Arrhenius equation. The activation energies varied from 49.18$\sim$149.55 kJ/mol depending on the relative humidity.