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Chaiwong K.,Chiang Mai University | Kiatsiriroat T.,Chiang Mai University | Vorayos N.,Chiang Mai University | Thararax C.,Rajamangala University of Technology at Lanna
Biomass and Bioenergy | Year: 2013

This study examined bio-oil and bio-char fuel produced from Spirulina Sp. by slow pyrolysis. A thermogravimetric analyser (TGA) was used to investigate the pyrolytic characteristics and essential components of algae. It was found that the temperature for the maximum degradation, 322°C, is lower than that of other biomass. With our fixed-bed reactor, 125g of dried Spirulina Sp. algae was fed under a nitrogen atmosphere until the temperature reached a set temperature between 450 and 600°C. It was found that the suitable temperature to obtain bio-char and bio-oil were at approximately 500 and 550°C respectively. The bio-oil components were identified by a gas chromatography/mass spectrometry (GC-MS). The saturated functional carbon of the bio-oil was in a range of heavy naphtha, kerosene and diesel oil. The energy consumption ratio (ECR) of bio-oil and bio-char was calculated, and the net energy output was positive. The ECR had an average value of 0.49. © 2013 Elsevier Ltd. Source

Jolanun B.,Rajamangala University of Technology at Lanna | Towprayoon S.,King Mongkuts University of Technology Thonburi
Bioresource Technology | Year: 2010

New granular material from clay residue was investigated as a bulking agent for food waste composting. Five mixing ratios of granule were conducted in a laboratory scale reactor at the desired low rate of air (0.05 l min-1). The evolution of temperature and the accumulative CO2 emissions were monitored. Physical and chemical changes, N loss, and organic matter degradation of compost were also examined. Adoption of granules of 15% V/V (FAS 31.6%) enhanced the thermophilic composting and CO2 emissions; thus satisfying the Process to Further Reduce Pathogens (PFRP, USEPA) as well as obtaining the highest rate constant of organic matter degradation (k = 0.005 day-1). As the amount of granules was doubled (35% V/V), the temperature was not only cooled, but also promoted the substantial N loss (54%). It was suggested that bulking agent from clay residue can be used beneficially as reusable media for microbial inoculation as analyzed by SEM. © 2010 Elsevier Ltd. All rights reserved. Source

Panomwan Na Ayuthaya R.,King Mongkuts University of Technology Thonburi | Namprakai P.,King Mongkuts University of Technology Thonburi | Ampun W.,Rajamangala University of Technology at Lanna
Renewable Energy | Year: 2013

This article presented an indoor experiment on developing a mathematical model for predicting the productivity of an ethanol solar still of basin type. The test still contained a horizontal evaporating surface and a condensing surface inclined 14° to a horizontal. Various concentrations of ethanol-water solution were employed for this experiment. The distillation temperature range included boiling point. The collected data were used to estimate the mass-transfer coefficient and mass transfer conductance of the solar still. Accordingly, a mathematical model was developed based on the Spalding theory of convection and the Fick's law of diffusion. In order to increase the performance at the outdoor conditions, a basin solar still was integrated with a set of fin-plate fitting in the still basin for distillation of a 10%v/v alcohol solution. It was found that the productivity of the modified solar still was increased by 15.5%, compared to that of a conventional still. Moreover, the predicted still efficiency by the model could increase to 46% when a number of fins that raised an effective absorptance were increased. Condition of high concentration output and high productivity was investigated. Monthly mean productivity and efficiency of the still were found to increase with daily mean insolation. © 2012 Elsevier Ltd. Source

Chunkag V.,King Mongkuts University of Technology Bangkok | Kamnarn U.,Rajamangala University of Technology at Lanna
IET Power Electronics | Year: 2010

The analysis and design of a paralleling three-phase ac to dc converter using CUK rectifier modules for DC Distributed Power System (DPS) applications are presented. The proposed control technique is used to obtain the three-inductor current compensators and to improve the dynamic response of the rectifier without affecting its steady-state performance and also to minimize total harmonic distortion (THDi) in the source current. As a result, the output voltage of the converter can withstand the variations of the dc load current and input voltage. The control method is employed in the voltage feedback loop. The implementation of this control circuit uses only analog circuitry. The experimental prototype has been built with a DC output voltage -48 V and output power 1.5 kW. Each converter operates in Continuous Conduction Mode together with hysteresis current control. The experimental results indicate that such scheme is effective and offers the good dynamic transient response. The results obtained are: power factor higher than 0.99 and THDi less than 3%. The system offers 88% efficiency and provides good inductor current sharing among the converter modules. The simulation and experimental results are presented to verify the feasibility of the control strategy. © 2010 © The Institution of Engineering and Technology. Source

Chotivisarut N.,Rajamangala University of Technology at Lanna | Nuntaphan A.,Electricity Generating Authority of Thailand | Kiatsiriroat T.,Chiang Mai University
Renewable Energy | Year: 2012

In this study, a concept of using thermosyphon heat pipe radiator to extract heat from water in a storage tank to generate cooling water during the nighttime was proposed. The cooling water could be used to serve the cooling load in a room during the daytime. A tested room with artificial load was constructed and a heat transfer model to calculate the water temperature during the nighttime and the room temperature during the daytime was developed. The simulated results agreed well with those of the experimental data. The model was used to find out the possibility of this concept for seasonal cooling load reduction of the similar building in the areas of different climates. The selected sites were Bangkok and Chiang Mai, Thailand and also Alice Springs, Australia where they are hot and humid, hot and semi-humid, and hot and semi-arid, respectively. Cooling water was produced during winter and used to serve cooling load in an air-conditioned building in summer. It found that, among three cities, Alice Spring showed a highest potential followed by Chiang Mai and Bangkok. The effect of controlled room temperature and UA of the room cooling coil on summer load fraction were shown. © 2011 Elsevier Ltd. Source

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