Papers by Keyword: Drying Rate

Abstract: The demand for food has been ever increasing in proportion with the growing human population. This includes agricultural products including fruits. Hence, food preservation for extended usage through drying is gaining importance. This study reports the drying behavior of several agricultural products, namely sweet potato, carrot, ginger, turmeric, passion fruit and its rind. Focus has been given to the effect of relative humidity on drying for these products at room temperature. Experiments were carried out at 27°C by varying relative humidity at 40%, 60% and 80%. It was found that the relative humidity has a strong effect on drying, with lower relative humidity providing higher drying rates. In humid surrounding like Malaysia which has an average humidity more than 70%, controlling humidity of drying air may result in an energy efficient process in comparison to raising the drying air temperature

Abstract: Surface preparation is a process of treating a surface to increase its attraction to coatings and imperative to ensure satisfactory coating can be attained. Conventional techniques of surface preparation usually involve blasting of abrasive material on the surface which usually associated with airborne debris and hazardous contaminant from the process. A relatively new technology in surface preparation is the usage of sponge media as an alternative to the conventional abrasive material. Being soft and elastic, sponge media can reduce airborne emission from surface preparation significantly while being able to be recycled. Unfortunately, the recovery of used sponge media becomes difficult during rainy conditions in which the sponge absorbs water and quickly becomes saturated. Therefore, this paper presents the drying characteristics of sponge media using a swirling fluidized bed dryer (SFBD) for rapid drying to overcome the long, inefficient sun drying as per current practice. Several laboratory scale experiments were carried out to dry water laden of the sponge media in the SFBD. Three bed loadings of 1.7, 2.0 and 2.3 kg were used at drying temperatures of 80°C, 90°C and 100°C. The experimental works revealed the excellent potential of the SFBD in drying the sponge media rapidly. The behaviour of moisture ratio and drying rate against time were discussed. Keywords: Sponge media drying, Swirling Fluidized Bed Dryer (SFBD), Moisture ratio, Drying rate

Abstract: Moisture distribution in sewage sludge was considered as the essential of thermal drying. Some methods were given in literatures to test the moisture distribution, but there was no standard method to determine the critical water content between different kinds of water. The municipal sewage sludge was dried by hot air in this work. Based on the drying curve, the derivative of drying rate with respect to dry basis moisture content was brought out to analyze the moisture distribution in sewage sludge. Results show that this method can easily determine the free water, interstitial water, surface water and bound water with a high accuracy. The present work can provide new insight to determine the moisture distribution in sewage sludge, which was still lacking in the literatures.

Abstract: Drying is essentially a process of simultaneous heat and mass transfer, in general, to remove moisture from a wet material to give a long shelf-life or to facilitate further processing. The drying medium flowing around the material serves to remove the moisture. In most drying operations, water is the liquid evaporated using air as the drying medium [. For each individual particle, the drying process involves moisture migration from the inner core regions to the particle surface. The surface moisture is then vaporized or evaporated into the drying medium.

Abstract: Microwave drying characteristics of Xilingol lignite were investigated with microwave drying testing equipment at 2450 MHz. Effects of particle size has been carefully studied. Mass losses of the samples were measured during drying. Drying rates were then obtained through the trends of drying curves. Results show the 0.6-1mm sample has low drying rate. Changing the stacking superficial area and size composition has been tested and resulted that only mixed with fine coal can increase the drying rate of 0.6-1mm. But classification experiment shows sieving 0-6mm sample into fine sample and coarse sample cannot advance the drying rate obviously.

Abstract: In order to improve the drying rate and to reduce the energy consumption of aquatic product, sea cucumber were treated with high pulse electric field (HPEF) in different frequency, and different voltage. The hot air drying rate of treated sea cucumber was determined and, meanwhile, several quality parameters such as the shrinkage and rehydration rate of samples with pretreatment were determined to compare with those of untreated samples. The results indicated that the hot air drying rate and rehydration rate of sea cucumber can be improved and the shrinkage of sea cucumber can be decreased by HPEF pretreatment, and while HPEF pretreatment was applied for 22.5kV at a frequency of 70Hz, the drying rate could be increased approximately 58%.

Abstract: Convectional dryerswork at high temperature and usually lead to loss of quality for sensitivebiomaterial products (especially in nutrition). In this way the researchersfound the microwave power more effective and suitable for drying processes. Someof microwave drying advantages include the following: short drying time, highquality of product, low operating temperature, flexibility in producing widerange of products and easier process controlling. The article calculated themoisture content and drying rate during drying process. Microwave power, holdertray speed, dimension of samples, irradiation time were considered; under theseconditions experiments were done and the results show that microwave method hasmore advantages as comparing with convectional methods.

Abstract: The low-temperature adsorption drying characteristics of thin-layer Angelica Dahurica were evaluated in a large scale dryer. The effects of drying medium temperature, relative humidity of drying medium and wind velocity on the drying characteristics were investigated. Page model using nonlinear regression method can preferably fit the drying characteristic of Angelica Dahurica under different drying conditions The work revealed the correlation between moisture content and drying process parameters. The drying coefficient and exponent in the page model can be expressed as a function of temperature, relative humidity and wind velocity of the drying air.

Abstract: The growing population demands adequate supply of food grains for its sustenance and supporting life activities. The agricultural produce in India has increased over the years due to improved farm practices despite of which the country is ranked 2^nd in terms of the number of children suffering malnutrition. It is reported that the child mortality rate in the country due to hunger and sanitation is above 1,000 per day. The post harvest losses in India are estimated at 4 to 6 percent for food grains and 16 to 18 percent for fruits and vegetables occurring at various stages of harvesting, storage and processing. The post harvest remedies for the loss of food grains and other agricultural produce includes better post harvest storage techniques based on removal of moisture to store the produce without being perished. The crop drying techniques based on use of renewable energy offer succor to save the large agricultural produce that goes to drains without being consumed.The reported work deals with design of a solar crop dryer for drying based on solar Photovoltaic/ Thermal (SPV/T) techniqueKeywordsPost harvest losses, solar crop drying, solar PV/T systems,drying rate

Abstract: To improve the drying rate and to reduce the energy consumption of aquatic product, scallop muscle were treated with high pulse electric field (HPEF) in different frequency, and different voltage. The hot air drying rate of treated scallop muscle was determined, meanwhile, several quality parameters such as the shrinkage and rehydration rate of samples with pretreatment were determined to compare with those of untreated samples. The results indicated that the drying rate of scallop muscle can be improved by HPEF pretreatment without affecting the quality, and 22.5kV for pretreatment voltage and 50Hz for pretreatment frequency is the optimum treated parameters.