Showing papers by "Wan Ramli Wan Daud published in 2009"

Study of the Drying Kinetics of Lemon Grass

Abstract: Problem statement: The thin- layer drying experiments were conducted to examine the effect of drying air temperature and humidity on the drying kinetics. Approach: A model to estimate the drying behavior of Lemon grass was developed). Results: Four different thin-layer drying models were compared with respect to their coefficient of determination (R2), Mean Bias Error (MBE) and Root Mean Square Error (RMSE). The one with highest (R2) and lowest (MBE) and (RMSE) was selected to better estimate the drying curves. Three temperatures (35, 45 and 55°C) and three humidities (30, 40 and 50%) were investigated with a fixed air velocity of 1 m sec-1. Conclusion/Recommendation: The increase in the drying air temperature increased the drying process and decreased the Equilibrium Moisture Content (EMC) of Lemon grass. The drying process decreased as the air humidity increases. The effect was less than that of the temperature. The EMC have high values with high relative humidity.

Low voltage power generation in a biofuel cell using anaerobic cultures.

Abstract: 2 Abstract: Biological fuel cell converts chemical energy exists in chemical bonds of organic substrates to electrical energy. The living cells in the anode chamber utilize substrate for the growth maintenance; as a result electrons are supplied. In this research paper, a dual chamber of microbial fuel cell was used. Several microorganisms such as Pseudomonas putida, Saccharomyces cerevisiae, Lactobacillus bulgaricus, Escherichia coli and Aspergillus niger were cultured in an anaerobic chamber for the generation of electrons. The system was started with initial glucose concentration of 30gl and the substrate consumption -1 was monitored for the incubation period of 48 hours. The rate of substrate consumption in the anaerobic compartment indicated that Saccharomyces cerevisiae had the great potential to generate electrons. Maximum voltage generated in the microbial fuel cell was 0.39v. The generated current was quite stable for the duration of 48 hours.

Rheological properties of Josapine pineapple juice at different stages of maturity

Abstract: The rheological behaviour of Josapine pineapple juice with at various maturity stages was studied at a wide range of temperature (5–65 °C) and concentration (4–14 °Brix) using a rotational rheometer as the measuring system. The results show that josapine pineapples juice demonstrated a Newtonian behavior and is influenced by maturity stage, temperature and concentration. The Arrhenius typed equation successfully describe the effect of temperature on the viscosity, on the other hand, the effect of concentration can be described better using exponential equation. Finally, an equation describing the combined effect of temperature and concentration on viscosity at different stages of maturity was successfully developed.

Drying Models and Quality Analysis of Sun-Dried Ciku

Abstract: Sun drying of ciku (Manilkara zapota) was carried out on different sample sizes to investigate the effects on drying kinetics. It was found that the maximum drying rates of sun-dried ciku decreased with larger product size. Three sunny days are needed to dry the ciku slabs to an average final moisture content of 0.2 g H2O/g dry mass. The results showed that hardness and chewiness of the dried samples were significantly different (p 0.05) compared to fresh ciku slabs. In addition, sun-dried ciku retained a total polyphenol content (TPC) that was relatively low (p < 0.05) compared to fresh ciku.

Non-Swirling Steady and Transient Flow Simulations in Short-Form Spray Dryers

Abstract: This paper numerically investigated the effect of chamber aspect ratio and operating conditions on flow stability within a short form spray dryer without the inclusion of droplet injection. Extensive analysis using different mesh configurations led to a new finding on the effect of expansion ratio on flow stability. A larger expansion ratio produces a more stable flow, which is due to the limitation of the jet fluctuation by the outlet geometry constriction. However, the flow might not be completely steady as fluctuations are magnified at higher inlet velocities, which can be explained by the confined jet feed-back mechanism. Fast Fourier Transform (FFT) analysis of the computed instantaneous velocity at selected spatial locations in the chamber revealed the effect of the chamber expansion ratio on periodicity of the flow structure. It is observed that changes in the expansion ratio primarily affect the amplitude of the 'noise' region in the frequency spectrum.

An Examination of the Solution Chemistry, Nucleation Kinetics, Crystal Morphology, and Polymorphic Behavior of Aqueous phase Batch Crystallized l-Isoleucine at the 250 mL Scale Size

Abstract: An examination of the aqueous solution solubility and batch crystallization kinetics of l-isoleucine at the 250 mL scale size under a poly- and isothermal process condition is presented. Solubility data determined are consistent with the existence of two l-isoleucine polymorphic forms, in which both forms have different solubility and they are enantiotropically related. These polymorphs (A and B) can be recovered at different cooling rates of cooling crystallization. Crystal characterization using optical microscopy, differential scanning calorimetry, X-ray powder diffraction, and Fourier transform IR microscopy confirm this polymorphic behavior. Polythermal crystallization kinetic studies revealed the crystallization temperature increases with cooling rate and solute concentration, which results in a decrease of the metastable zone width (MSZW) with a decreasing cooling/heating rate. The study also revealed that cooling rates affect the polymorph formation, where at cooling rates of 0.25−0.75 °C/min, for...

Quality Changes of Superheated Steam–Dried Fibers from Oil Palm Empty Fruit Bunches

Abstract: Conventional drying of the fibers from oil palm empty fruit bunches (EFB) using flue gas from diesel burners frequently causes browning and dust explosion. Replacing the drying medium with superheated steam is expected to improve the quality of EFB fibers as well as improve the safety of the dryer operation. In this study, the effects of steam temperature and steam velocity on the quality of steam–dried EFB fibers was investigated. The drying experiment was carried out at atmospheric pressure with steam superficial velocity in the range of 0.3 to 0.49 m s−1 and temperature in the range of 135 to 200°C. Three quality parameters of the EFB fibers, the color, strength, and microstructure, were used to assess the changes in EFB fiber quality as a result of superheated steam drying. The color of the EFB fiber was either improved or not significantly degraded. The strength of the superheated steam–dried EFB fibers was higher than that of undried and hot air–dried EFB fibers. The microstructure of fresh undried ...

An experimental analysis of solar-assisted chemical heat pump dryer

Abstract: The performance of a solar-assisted chemical heat pump dryer has been studied under the meteorological conditions of Malaysia. The system consists of four mean components: solar collector (evacuated tubes type), storage tank, solid--gas chemical heat pump (CHP) unit and dryer chamber. A solid--gas CHP unit consists of a reactor, condenser and evaporator. The reaction (CaCl 2 --NH 3 ) has been used in this study. A series of experiments have been performed on the system under varied conditions for two days. The maximum values of solar fraction from the experiments on clear and cloudy days are 0.713 and 0.322, respectively; whereas the coefficient of performance of CHP (COP-super-h) maximum values of 2 and 1.42 are obtained from the experiments on clear and cloudy days, respectively. The total system energy output from the experiment on a clear day is 51 kWh against 25 kWh on a cloudy day. Any reduction of energy at the condenser as a result of decrease in solar radiation will decrease the coefficient of performance as well as the efficiency of drying. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.

Physico-Mechanical properties of the Josapine Pineapple Fruits.

Abstract: The physico-mechanical properties data of fruits are important in the design of various handling, packing, and storage and transportation system. The physical-mechanical properties of pineapple fruit from the Josapine variety, namely the weight of the fruit (with and without peel), pulp to peel ratio, diameter of the whole fruit (with and without peel), at three different positions along the longitudinal axis of the fruit, length of the fruit (with and without peel) and the length of crown were studied using the standard method at seven stages of maturity during storage at 25°C and 52% (RH). The effect of fruit maturity on the firmness of each fruit at three different locations was measured using a cylindrical die of 6 mm in diameter with the Instron Universal Testing Machine. The results indicated that the average total weight of a single fruit is 886.86±49.67 g. The average pulp to peel ratio is 1.91. The average diameter (with and without peel) was 86.83±5.24 mm and 80.95±4.15 mm (top section), 100.77±3.84 mm and 90.19±3.73 mm (middle section) and 97.17±3.49 mm and 73.30±5.11 mm (bottom section), respectively. The average length of the fruit (with and without peel) was 126.65 mm and 113.64 mm, respectively. The average length of crown was 89.13 mm. The firmness of the fruits was found to decrease with the stage of maturity. These data are important in determining the optimum stage of maturity for fruit processing.

Solar Chemical Heat Pump Drying System for Tropical Region

Abstract: Solar assisted chemical heat pump drying system for tropical region has been studied. A simulation has been done under the meteorological conditions of Malaysia. The system consists of four mean components, solar collector (evacuated tubes type), storage tank, chemical heat pump units and dryer chamber. The monthly efficiency for evacuated tube solar collector has been predicted to be between the range (59 - 64%) with the deference between mean collector temperature and ambient temperature 20 oC. The solar fraction as a function of solar collector area has been studied. It was found that as the collector area increases the loss increases and hence the solar fraction increases. A monthly coefficient of performance for heating (COP h ) for chemical heat pump has been predicted and the maximum value of 1.8 as function for solar collector area 10 m 2 and storage tank size 0.2 m 3 were found. Any reduction of energy at condenser as a result of the decrease in solar radiation which in the final decrease the coefficient of performance as well as decrease the efficiency of drying.

Multi-Composition Cu-Zn-Al Catalyst Supported on ZSM-5 for Hydrogen Production

Abstract: Multi-composition Cu-Zn-Al (CZA) catalyst system supported on aluminosilicate zeolite (ZSM-5) was prepared by the impregnation method. The experiments were performed by varying the metal composition using statistical experimental design method namely Simplex Centroid Design. A series of catalysts were prepared by varying the different metal content in the composition up to 15 % supported on 85% ZSM-5. BrunauerEmmett-Teller method (BET) was adopted to characterise the surface area of the prepared catalyst. The reduction properties of the catalyst were ascertained using temperature programmed reduction (TPR) technique. The CO adsorption capabilities of the catalysts at 60, 200, 225, 250, 275 and 300 °C have been investigated using chemisorption method. Xray diffraction (XRD) technique was adopted to evaluate the structure of the catalysts. The shape and morphology of the catalysts were analysed using scanning electron microscopy– energy dispersive x-ray (SEM-EDX). The multifunctional Cu, Zn and Al catalyst supported on ZSM-5 showed a high BET surface area of about 132 ~ 196 m 2 /g. The TPR profiles showed the occurrence of reduction in a temperature range of 230 – 260oC. The performance of the catalyst in stream reforming methanol (SRM) and auto thermal steam reforming methanol (ATRM) processes suggested that, a maximum hydrogen yield of 73.09 and 76.88 mol% could be obtained with Cu6Zn7Al2/ZSM-5 catalyst in SRM and

Kinetics of Mass Transfer, Colour, Total Polyphenol and Texture Change of Manilkara Zapota During Convective Air Drying

Abstract: The effects of air temperature and product size on drying kinetics, retained total polyphenol content (TPC), hardness kinetics and total colour change (.E) kinetics of ciku (Manilkara zapota) were investigated. In addition, five terms of the theoretical model were used to estimate the effective diffusivity values during drying at temperatures from40OC to 70OC. The drying rates of dried ciku were increased with increasing temperature and decreasing product size. It was found that hardness of ciku dried at temperature higher than 60OC increased significantly, when the moisture content was reduced toless than 0.5 g H2O/g DM (dry basis). In terms of nutritional value, the retained total polyphenol content (TPC) of dried ciku in hot air drying also increasing with temperature. The highest retained TPC was 141 mg GAE/ 100g of samples, which can be obtained from drying at 70OC.

Compact pressure swing adsorption system for hydrogen purification

Abstract: A compact pressure swing adsorption system for gas separation and purification, comprising an absorption chamber, means for pressurizing the adsorption chamber with a gas stream (60) fed by an inputting means; means for adsorbing impurity gas (58) from the gas stream (60) and conveying purified gas (56) to an outputting means; means for depressurizing the adsorption chamber to regenerate absorbed impurity gas (58); and means for purging any remaining adsorbed impurity gas (58) by a purge gas (55); wherein the adsorption chamber comprises a plurality of separate cells, each cell having adsorbent bed (51, 52, 53, 54), and the inputting and outputting means are connected to each cell with means for switching between the cells so that only one cell at a time is connected to the inputting means and another cell is connected to the outputting means, by a network of pipes and valves (57).

Experimental performance of solid-gas chemical heat pump in solar chemical heat pump dryer

Abstract: A solar assisted chemical heat pump dryer has been designed, fabricated and tested. The performance of the system has been studied under the meteorological conditions of Malaysia. The system consists of four mean components: solar collector (evacuated tubes type), storage tank, solid – gas chemical heat pump units and dryer chamber. A solid gas chemical heat pump unit consists of reactor, condenser and evaporator. The reaction used in this study (CaCL2-NH3). The maximum experimental value of the COP for the solid-gas chemical heat pump of 2 was found, and the total system energy output is 51 kWh over drying time about 9 hours. The results show that any reduction of energy at condenser as a result of a decrease in solar radiation which in the final decrease the coefficient of performance as well as decrease the efficiency of drying.