Abstract: Intelligent diagnostics tool for detecting damaged bevel gears was developed based on wavelet support vector machine (WSVM). In this technique, the existing method of SVM was modified by introducing Haar wavelet function as kernel for mapping input data into feature space. The developed method was experimentally evaluated by vibration data measured from test rig machinery fault simulator (MFS). There were four conditions of gears namely normal, worn, teeth defect and one missing-teeth which has been experimented. Statistical features were then calculated from vibration signals and they were employed as input data for training WSVM. Fault diagnostics of bevel gear was performed by executing classification task in trained WSVM. The accuracy of fault diagnostics were evaluated by testing procedure through vibration data acquired from test rig. The results show that the proposed system gives plausible performance in fault diagnostics based on experimental work.
Abstract: The emergence of natural fiber as a potential alternative for glass fibre replacement has seen various development and investigation for various applications. However, the main issue with the natural fibre reinforced composites is related to its susceptibility to impact damage. This paper presents a preliminary case study of damage identification in Natural Fibre Composites (NFCs). The study involves a simple experiment of impact on a NFC panel. The strain data are measured using piezoceramic sensors and the response signal was investigated. Then an effective impact damage procedure is established using a neural network approach. The system was trained to predict the damage size based on the actual experimental data using regression method. The results demonstrated that the trained networks were capable to predict the damage size accurately. The best performance was achieved for an MLP network trained with maximum signal features, which recorded the error less than 0.50%.
Abstract: The experimental study has been made to investigate heat transfer and pressure drop for air flow around finned flat tube banks in-line configurations with laminar forced convection. Measurements were conducted for twelve tubes in the flow direction, four tubes in the row. Four air velocity (0.2, 0.5, 0.8 and 2.0 m/s) identical to the Reynolds number, ReDh based hydraulic diameter was varied between 124 and 1238. The total heat flux supplies in all tubes change four times from 473.2 to 3871.7 W/m2. The study results indicate that the average heat transfer coefficient, and the average Nusselt number, of all tubes has increased 113.6%–150.3% with ReDh numbers varying from 124 to 1238 at the fixed heat flux. Likewise, the friction factor decreases 57.7% with a ReDh number range 124 – 1238.
Abstract: Domestic hot water preparation systems with flat plate solar collectors are widely used in Turkey. In this collector, the temperature difference between the required water temperature and the ambient air temperature increase causes a decrease in the efficiency of the collector. In this study, the use of double glass in order to increase the efficiency of the collector is studied experimentally.The location is in Isparta South West Turkey. Experimental study is conducted in May 2013 at the Suleyman Demirel University, Isparta. The system components are solar simulator, solar collector, tank, circulation pump, flowmeter, thermocouples, data acquisition device and solar sensor. Solar collector system’s operating temperature is 50 oC for winter also summer. The difference between the collector temperature and the ambient air temperature exceeds 25 oC in many cases, were found to be more efficient double-glazed collectors. When the temperature difference is 40 oC, using double glazing collector is 24% more efficient than using single glazing collector.
Abstract: Tangentially fired boilers are widely used in generating electricity power due to its advantage of distributing heat evenly to all furnace walls. However, this type of boiler poses common temperature deviation at the upper furnace which may lead to temperature imbalance. This consequently may reduce the performance of the boiler which cannot be simply ignored. This paper investigates the flow and temperature imbalance in a 700 MW coal-fired boiler at full load and reduced load conditions. The effect of loading condition towards the temperature imbalance is investigated. It is observed that temperature imbalance occurs at the reheater plane between left wall and right wall where higher temperature was found near the left wall. Temperature imbalance is influenced by the loading condition, the higher the loading the higher the imbalance.
Abstract: Spray losses are the most important problem that is faced in the spray application process as result of spray drift to non target areas by the action of air flow.This paper investigated the spray drift for banding applicationusing even flat-fan nozzle TPEunder wind tunnel conditions.In addition, this paper also examined the effect of different spray fan angles 65°, 80° and 95° on spray drift particularly where there is need to make the nozzle operate at the optimum heights above the ground or plant level.In addition, three cross wind speeds 1, 2 and 3m/swere produced to determine the effect of wind speed on total spray drift.According to the results from this study, the nozzle anglehas a significant effect on the total spray drift. The nozzle angle 65° gave the highest drift reduction compared to the other nozzle angles. The maximum driftfor all nozzles was found at nozzle height of 60 cm. The minimum mean value of the drift was found at wind speed of 1 m/s. This study supports the use of nozzle angles of less than 95° on heights more than 0.5m and on wind speeds more than 1m/s as a means for minimizing spray drift.
Abstract: In particle deposition problems, colloidal potentials play an important role in adsorpting the colloidal particles onto the surface of the deposit wall once the colloids arrive in the vicinity of the wall. Therefore it is important to gain understanding of these potentials, in particular, how they are influenced by the problem parameters. With such an understanding, more insights into mitigating the problem can be obtained, and consequently, more effective approaches to tackle the problem can be taken. In this work, we present the effects of particle size, flow temperature and ionic strength of the solution on the colloidal potentials based on numerical analysis. The results support the conclusion that the rate of initial deposition of particles can be reduced if the particle size is smaller, the flow temperature is increased, and the ionic strength is reduced.
Abstract: This paper presents the findings of a thermal comfort survey conducted in a tropical green office building. The building was installed with a slab-integrated radiant cooling system, which operated concurrently with an integrated variable-air-volume system. Evaluation of indoor thermal environment was made, where both objective and subjective assessments were carried out. The air temperature, air velocity, relative humidity and surface temperatures were measured by using calibrated sensors. Based on the data collected from the field assessment, the thermal comforts indices with expectancy factor were calculated. The results showed that thermal comfort parameters were within the comfort range specified in a local guideline, except for the air velocity profile. Besides, discrepancy between the Predicted Mean Vote (PMV) with expectancy factor and Actual Mean Vote (AMV) was found, which showed that the former still overestimated the thermal sensation of occupants although an expectancy factor of 0.5 was used.
Abstract: Influences of twisted coil plate insert on the performance of fire tube boiler using were experimentally investigated. In this study, the twisted coil plate was placed inside the tube to illustrate boiler performance. The performances of boiler were studied in terms of operating time taken, exhaust flue gas temperature, steam temperature and boiler efficiency. The boiler was operated with 50%, 100% and without tube coil plate inserts at low and high fire burner setting. Based on the results obtained, effect of twisted plate insert and without insert were observed. There is an enhancement in boiler performance in terms of boiler efficiency. The ANSYS Fluent simulation showed the effect of width ratio and twist ratio. Therefore, the experimental results indicate that using twisted coil plate in the boiler is one of the best ways to improve boiler performance.
Abstract: This analysis considers the computational simulations of the temperature distribution of a propane-air customary flame combusted from an aeronautical fire-certification set according to the ISO2685standard. The numerical codes have been executed in Computational Fluid Dyanmics using the k-ω SST turbulence model coupled with eddy-dissipation. The resultshowsthat the maximum predicted temperature using the standard flame settings exceeds the required temperature for evaluation of a fire-resistive material. The mole fractions of the by-products, carbon dioxide and water have also been predicted.