Somchai Maneewan

Improving Mechanical Properties of Autoclaved Aerated Concrete by Sugar Sediment

The comparison of microstructure and mechanical properties between the autoclaved aerated concrete (AAC) and the autoclaved aerated concrete consist of sugar sediment (AAC-SS) was investigated in this work. The microstructure of AAC and AAC-SS was analyzed by the scanning electron microscopy (SEM). The mechanical properties of AAC and AAC-SS were focused on the compressive strength, the density, the water absorption and the flexural strength. To comfirm the tobermorite phase, the phase formation of the samples was tested using X-ray diffraction (XRD). It was found that the microstructure of AAC and AAC-SS surface was the finer needle-like crystalline morphology. The compressive strength (5.9 N/mm2) and flexural strength (1.82 N/mm2) of AAC-SS were higher than that of the AAC (5.0 N/mm2 and 1.64 N/mm2). While, the value of density (0.60 g/cm3) and humidity (23.59%) of AAC-SS had little less than that of the AAC (0.61 g/cm3 and 24.11%). The increasing of the tobermorite phase, which was added by the sugar sediment, had affected to the improvement of the mechanical properties. The specimens of both AAC and AAC-SS were claimed in quality class of 4, which based on the Thai Industrial Standard 1505-1998.

Thermoelectric generator for the recovery of energy from the low grade heat sources in sugar industry

Received May 21, 2018 Revised Aug 30, 2018 Accepted Sep 13, 2018 This paper presents a novel Stator Current based Model Reference Adaptive System (SC_MRAS) speed observer for high-performance Six Phases Induction Motor (SPIM) drives using linear neural network. The article aim is intended to improve performance of an SC_MRAS observer, which were presented in the literature. In this proposed scheme, the measured stator current components are used as the reference model of the MRAS observer to avoid the use of a pure integrator and reduce the influence of motor parameter variation. The adaptive model uses a two-layer Neural Network (NN) to estimate the stator current, which has been trained online by means of a Least Squares (LS) algorithm instead of uses a nonlinear Back Propagation Network (BPN) algorithm to reduce the complexity and computational burden, it also help to improve some disadvantages cause by the inherent nonlinearity of the BPN algorithm as local minima, two heuristically chosen parameters, initialization, and convergence problems, paralysis of the neural network. The adaptive model of the proposed scheme is employed in prediction mode, not in simulation mode as is usually the case in the literature, this made the proposed observer operate better accuracy and stability. In the proposed observer, stator and rotor resistance values are estimated online, these values thereafter were updated for the current observer and rotor flux identifier to enhance the accuracy, robustness and insensitivity to parameters variation for the proposed observer. The proposed LS SC_MRAS observer has been verified thought the simulation and compared with the BPN MRAS observer. The simulation results have proven that the speed is estimated a consequent quicker convergence, do not need the estimated speed filter, lower estimation errors both in transient and steady state operation, better behavior in low and zero speed operation. Keyword:Received Jun 7, 2018 Revised Jul 8, 2018 Accepted Sep 13, 2018 Experiments confirmed that Transformerless Inverters (TIs) deliver more reliability and higher energy efficiency. Nonetheless, one of the shortcomings of TIs is the leakage current that occurs between the photovoltaic (PV) string terminals and the ground. Such a drawback is justified by the non-galvanic isolation caused by the transformer being omitted. As such, this study is intended to develop a novel TI inverter topology for solar PV systems. The latter is meant to remove the leakage current and enhance the operating system of the entire PV conversion as well. Added to its null zero-crossing distortion and capability regarding energy efficiency, the developed TI, being validated by simulation and experiment, eradicated the leakage current. Keyword:Now a day’s renewable energy sources became an interesting area of research of which fuel cells are emerged as an alternative source for producing electricity to meet the energy crisis. This led to a research on power conditioning systems through which fuel cell is interfaced to the utility. Of the different converter topologies Isolated full bridge boost converter (IFBC) topology is most suitable for fuel cell applications. In this paper a Predictive Switching Modulator (PSM) Control is proposed for the converter topology and its performance is compared with Linear Peak Current Mode control (LPCM), Non-Linear Carrier Control (NLC).Received May 2, 2018 Revised Aug 23, 2018 Accepted Sep 14, 2018 Recently of the main topic of research is the sensorless vector control of induction motor drive, In this paper presents the predictive model reference adaptive system (PMRAS) rotor speed observer, This observer developed from the classical MRAS rotor flux scheme associated with predictive adaptation mechanism designed from the Finite Control Set Model Predictive Control (FCS–MPC) by using a search optimization algorithm for calculate the rotor position which guarantee a minimum speed tuning error signal at each sampling period. The effectiveness of the proposed observer proved with the simulation results, show high dynamic performance speed and position observed in sensorless vector control process at low and zero speed as well robustness against motor parameter variation with different loading conditions. Keyword:

The optimization of hybrid air ventilation system combined with silica gel and thermoelectric using monitoring control

Received May 21, 2018 Revised Aug 30, 2018 Accepted Sep 13, 2018 This paper presents a novel Stator Current based Model Reference Adaptive System (SC_MRAS) speed observer for high-performance Six Phases Induction Motor (SPIM) drives using linear neural network. The article aim is intended to improve performance of an SC_MRAS observer, which were presented in the literature. In this proposed scheme, the measured stator current components are used as the reference model of the MRAS observer to avoid the use of a pure integrator and reduce the influence of motor parameter variation. The adaptive model uses a two-layer Neural Network (NN) to estimate the stator current, which has been trained online by means of a Least Squares (LS) algorithm instead of uses a nonlinear Back Propagation Network (BPN) algorithm to reduce the complexity and computational burden, it also help to improve some disadvantages cause by the inherent nonlinearity of the BPN algorithm as local minima, two heuristically chosen parameters, initialization, and convergence problems, paralysis of the neural network. The adaptive model of the proposed scheme is employed in prediction mode, not in simulation mode as is usually the case in the literature, this made the proposed observer operate better accuracy and stability. In the proposed observer, stator and rotor resistance values are estimated online, these values thereafter were updated for the current observer and rotor flux identifier to enhance the accuracy, robustness and insensitivity to parameters variation for the proposed observer. The proposed LS SC_MRAS observer has been verified thought the simulation and compared with the BPN MRAS observer. The simulation results have proven that the speed is estimated a consequent quicker convergence, do not need the estimated speed filter, lower estimation errors both in transient and steady state operation, better behavior in low and zero speed operation. Keyword:Received Jun 7, 2018 Revised Jul 8, 2018 Accepted Sep 13, 2018 Experiments confirmed that Transformerless Inverters (TIs) deliver more reliability and higher energy efficiency. Nonetheless, one of the shortcomings of TIs is the leakage current that occurs between the photovoltaic (PV) string terminals and the ground. Such a drawback is justified by the non-galvanic isolation caused by the transformer being omitted. As such, this study is intended to develop a novel TI inverter topology for solar PV systems. The latter is meant to remove the leakage current and enhance the operating system of the entire PV conversion as well. Added to its null zero-crossing distortion and capability regarding energy efficiency, the developed TI, being validated by simulation and experiment, eradicated the leakage current. Keyword:Now a day’s renewable energy sources became an interesting area of research of which fuel cells are emerged as an alternative source for producing electricity to meet the energy crisis. This led to a research on power conditioning systems through which fuel cell is interfaced to the utility. Of the different converter topologies Isolated full bridge boost converter (IFBC) topology is most suitable for fuel cell applications. In this paper a Predictive Switching Modulator (PSM) Control is proposed for the converter topology and its performance is compared with Linear Peak Current Mode control (LPCM), Non-Linear Carrier Control (NLC).Received May 2, 2018 Revised Aug 23, 2018 Accepted Sep 14, 2018 Recently of the main topic of research is the sensorless vector control of induction motor drive, In this paper presents the predictive model reference adaptive system (PMRAS) rotor speed observer, This observer developed from the classical MRAS rotor flux scheme associated with predictive adaptation mechanism designed from the Finite Control Set Model Predictive Control (FCS–MPC) by using a search optimization algorithm for calculate the rotor position which guarantee a minimum speed tuning error signal at each sampling period. The effectiveness of the proposed observer proved with the simulation results, show high dynamic performance speed and position observed in sensorless vector control process at low and zero speed as well robustness against motor parameter variation with different loading conditions. Keyword:

Utilization of Sugar Sediment Waste for a Low Cost Lightweight Concrete Development with Environmental Impact Reduction

Waste sugar sediment was included in the mix of lightweight concrete. The optimum mix that we identified was 10% by weight replacement of lime by sugar sediment. The resultant product exhibited the highest compressive strength of approximately 5.5 N/mm2, and demonstrated that a substantial proportion of the 872 million kgs of waste sugar sediment produced in Thailand per year could be diverted from landfills, providing substantial economic and environmental benefits. Our analysis indicates that about 13 million kgs of lime could be replaced by an equal amount of sugar sediment, 13 million kgs, per year, if the improved composition of lightweight autoclaved aerated concrete is adopted by the construction industry on a wide scale. As the cost of lime is about 2 Baht per kg, and sugar sediment is essentially a free input, an estimated 26,000,000 Baht per year savings is achievable. The economic, environmental and health impacts of reducing this industrial waste going into landfill areas by 13 million kgs per year must also be seen as substantial.

Investigation of Physical, Mechanical and Thermal Properties of Building Wall Materials

This research concentrates to the effect of changing sand proportion on the physical, mechanical and thermal properties of building wall materials (Cellular lightweight concrete). The density, water absorption and compressive strength of the 7.0 cm x 7.0 cm x 7.0 cm concrete sample were studied. It was found that there are an increase of density and a reduction of water absorption with an increase of sand content. The higher compressive strength can be confirmed by higher density and lower water absorption. The physical and mechanical properties of lightweight concrete conditions conformed to the Thai Industrial Standard 2601-2013. The phases of CaCO3 and calcium silicate hydrate (C-S-H) in the material indicate an important factor in thermal insulating performance.

A COMPARISON OF THE ENVIRONMENTAL IMPACT OF SOLAR POWER GENERATION USING MULTICRYSTALLINE SILICON AND THIN FILM OF AMORPHOUS SILICON SOLAR CELLS: CASE STUDY IN THAILAND

This paper studies the environmental impact of two different forms of solar power generation in Thailand – that of multicrystalline silicon solar cells, and that of thin film amorphous silicon solar cells. It takes as its study two of the largest solar cell power plants of their kind in Thailand; a multicrystalline silicon plant in the north (generating 90 MW) and a thin film amorphous silicon plant in the centre (generating 55 MW). The Life Cycle Assessment tool (LCA) was used to assess the environmental impact of each stage of the process, from the manufacture of the cells, through to their transportation, installation and eventual recycling. The functional unit of the study was the generation of 1 kWh of power transmitted and distributed by the Electricity Generating Authority of Thailand (EGAT) and Provincial Electricity Authority (PEA). The environmental impact results were calculated in terms of eco-points (Pt) per functional unit of 1 kWh. The characterised data for 1 kWh of solar power generation was then compared with data for 1 kWh of combined cycle and thermal power generation (both in Thailand), using the same set of characterisation factors. After analyzing the results, both forms of solar power energy generation were found to impact upon the studied categories of Human Health, Ecosystem Quality and Resource Depletion, whilst also highlighting the importance of the solar cell module recycling process in decreasing the overall environmental impact. When the two solar cell technologies were compared, the overall impact of the multicrystalline silicon solar cell was found to be higher than that of the thin film amorphous silicon solar cell. Furthermore, when assessing the overall impact against non-renewable power generating technologies such as combined cycle and thermal power generation, the thin film amorphous silicon solar cells were found to have the lowest environmental impact of all technologies studied.

Experimental Investigation of Heat Transfer of Refrigerant Fluid Pulsating Heat Pipe

Heat transfer performances of a pulsating heat pipe (PHP) having internal and external diameter with 4.5 mm and 6 mm with various contents of refrigerant are experimentally investigated. The working fluid as R404A refrigerant was filled in the volume ratios from 0% to 80% and the heat input was controlled in the range from 10 W to 80 W. Obtained results exhibited the ability of R404A refrigerant can enhance the thermal performance in steady state condition. The average temperature difference of the evaporating section and condensing section in the 80% filling volume ratio decreased from 9.5 °C to 2.5 °C when the heating power increase from 10 W to 80 W. The thermal resistance of evaporator and condenser decreased with an increase of the heat input as well. For other filling volume ratios, the trend of temperature difference and thermal resistance was similar to that of the 80% volume filling ratio. Considering the same heat input, the highest heat transfer performance was found at the 80% volume filling ratio. Refrigerant with a relatively low dynamic consistency can lead to relatively high velocity in the PHP that can reduce the temperature difference between the evaporating section and condensing section.

Effects of Fresnel Len Application on PV Module Performance

Effects of shading and blocking of solar radiation intensity through Fresnel lens onto solar cell were investigated in this work. Fresnel lens was made of polyvinyl chloride to concentrate the solar radiation onto the polycrystalline silicon solar cell with the 0.767 m x 0.670 m in size and no cooling under the solar panels. The temperature and efficiency comparisons between solar module with and without Fresnel lens were observed. The performance of the two modules overtime is assessed by monitoring the characteristic I-V and P-V curves. The maximum efficiency of the solar panels with Fresnel lens and without Fresnel lens in each hour was approximately 5-6.7% and 8.8-11.5%, respectively. This lower efficiency of PV module with Fresnel lens was a result of unsuitable distance of Fresnel lens that operated with the PV module.

Coefficient of Performance of Thermoelectric Cooling on Nanofluids

This paper reports on experimental comparisons of coefficient of performance (COP) of a thermoelectric coolingsystem which cooled the hot side of the TEC by water (wc), ethylene glycol (egc) and nanofluids (nfc) The nanofluids is composed of ethylene glycol with silver nano(35 nm).The TEC was composed of the TE cooling modules, heat exchanger, and the air cooled heat sink at the cold side of the TE modules.Experiments were conducted with various current input 1 - 4.5 A to find out the optimum current input condition. To consideration of cooling capacity and COP of system was measured the hot and cold side temperature of TEC. Results shown that, the cooling capacity was increased with current input. The maximum cooling capacity of nfc, egc and wc are about 72, 62 and 41 W, respectively. Considered with highest COP found that the optimum current input is approximately 2.5 A. The maximum COP of nfc, egc and wc are about 2.01, 1.7 and 1.12, respectively. Therefore, the proposed TEC-nfc concept is expected to contribute to wider applications of the TE cooling system.

Feasibility of Refuse Derived Fuel 5 Composed of the Mechanical Biological Waste Treatment and Crude Oil Sludge

The main focus of this paper is concerned with the production and properties of refuse derived fuel 5 (RDF-5) for use in energy from waste technologies. The analysis was performed using feedstocks made up of residues from a range of mechanical biological treatment (MBT) plants and crude oil sludge. The RDF-5 was composed of crude oil sludge and mechanical biological waste treatment (MBWT). The ratios of MBWT to crude oil sludge were 5:95, 10:90, 15:85 and 20:80 respectively. The physical and thermal characteristics of RDF-5 were examined. This was further investigated in the context of the parameters required during production and the properties of RDF-5. RDF-5 was produced using a screw compactor. Analysis of the optimal mixing ratios between the crude oil sludge and MBWT were undertaken by testing the thermal value based on ASTM D 240 moisture contents was based on ASTM D 3173, ash was based on ASTM D 3174, and density was based on ASTM E 75 respectively. The results showed that the optimal ratios of MBWT to crude oil sludge were 15:85 and 20:80 have feasibility to produce the RDF-5. Because of the ratios of 15:85 and 20:80 have a high value 10,831 kcal/kg and 11,260 kcal/kg, the percentages of moisture were 2.73% and 5.93% and the density values were 750 kg/m3 and 806 kg/m3 respectively (RDF-5 has a high heating value (HHV > 5,000 kcal/kg), with the percentage of moisture content not exceeding 10 percent and the density value (D 600 kg/m3) according to production of solid fuels standards). The ash values were 5.10% and 4.74% respectively. Comparing the energy production costs between RDF-5 and other fuels used in Thailand we found that the production costs of RDF-5 were 0.014 /MJ and 0.013 /MJ which are comparable to that of paddy husk and much cheaper than those of fuel lignite and bituminous. This preliminary evaluation reveals that the recovery of energy through RDF-5 production from MBWT with crude oil sludge is cost attractive and it should be considered as a feasible option for utilizing energy from MBWT with crude oil sludge.