Model for estimation of global solar radiation in Sarawak, Malaysia

The aim of this work was to estimate the obtainable amount of global solar radiation for the development of solar photovoltaic power systems at four locations namely Sri Aman, Sibu, Bintulu and Limbang in Sarawak, Malaysia

Comparison of solar photovoltaic module temperature models

This paper presents the comparative study of the different models that used to predict the solar photovoltaic module temperature, which is one of the most important factors responsible for lowering the performance of photovoltaic modules. The approach of the different models was examined in order to evaluate the estimated behavior of module temperature increase with respect to ambient temperature and solar radiation. A total of 16 models have been reviewed by employing monthly mean daily meteological data of Kuching, Sarawak. The most models showed similar trend of increase or decrease of sola photovoltaic module temperature due variation of solar radiation intersity. However, the results of reviewed models were quite different under constant solar radiation and ambient temperature conditions. It was found that the variation in the results was due to the use of different variables, climatic conditions, configuration of photovoltaic modules and the approach used by various researchers in the models

Flow visualization of a dielectric barrier discharge plasma actuator

The optimum operating conditions of dielectric barrier discharge (DBD) plasma actuators were determined using both the quantitative and qualitative methods. The quantitative study was carried out by estimating DBD discharge power using the theoretical and experimental methods. The theoretical analysis was carried out to find a mathematical model, which describe the discharge power of the DBD actuator. The estimated results from the mathematical model were compared with the experimental values obtained from Lissajous figures. The qualitative analysis was used for the plasma flow visualization. The effects of the DBD design parameters were studied through the images captured using a high speed charge-coupled device camera. Simulation work was done in order to obtain an insight of the electric field responsible for the plasma formation using the commercial computer software. The results revealed that the performance of the DBD plasma actuator was influenced by various design parameters, especially by dielectric thickness and controlled by the input voltage characteristics

Operational Parameters Assessment of a Biomass-To-Fuel Gas Converter

This study presents the assessment on the existing mini-sized biomass-to-fuel gas (B2F) converter. Operational parameters, such as composition of after filtered residual liquid (AFRL), composition of raw combustible fuel gases produced using wood chips and coal as feedstock, and nearby incremental levels of carbon monoxide and suspended particulate during operation, are determined. Analysis results of the raw (unburnt) combustible fuel gases from low grade Balingian-Mukah coal and wood chips found that there were approximately 23-29% gasoline constituents; 15-30% diesel constituents; 1-16% CO2; 10-13% O2, CO, SO, NO and H2O; 46-71% combustible gases. It was observed that the phenol contained in the AFRL recorded approximately 5,310 mg/L. Moreover, by-products, such as 1.5% tars and 13% AFRL, were produced. The result shows that a B2F converter is suitable to harvest the combustible gases that can be used as fuel for internal combustion engines. However, the amount of organics indicated that the AFRL should not be discharged directly into watercourses without pre-treatment

Comparison Study between FEM Simulation and Experimental of Heat and Mass Transfer in Kek Lapis Sarawak Baking

Kek Lapis Sarawak is specialty dish from Sarawak. Kek Lapis Sarawak industry contributes a lot to the state’s economy. In cake industry, the use of oven in the baking process contributes to high energy consumption. Nowadays, energy has become an operational issue and there is a need to minimize energy consumption to reduce production cost. This research aims to optimize the baking process for an efficient energy consumption. Therefore, it is important to investigate the relationship between baking temperature, time and cake quality. Accurate temperature and time will define an efficient baking process. Kek Lapis Sarawak baking process has been modelled and simulated using finite element method (FEM). Results from the model was validated with an experiment. There is specific oven temperature needed to enable perfect gelatinization and coagulation to happen which is 190 °C. While baking time are varied by layers. The baking time is reducing as more layers added.  The finding shows interdependent relationship between porosity, thermal conductivity and moisture content where higher porosity  can lead to poor thermal conductivity

Pressure stresses generated due to supersonic steam jet induced hydrodynamic instabilities

The phenomenon that involves direct contact of steam with water is called Direct Contact Condensation (DCC). This phenomenon has been observed/prevailed in most of the power and process industries. The phenomenon of direct contact condensation involves heat, mass and momentum transfer across the highly fluctuating interface between steam jet and surrounding water giving this process an intricate nature to be studied. More recently the observation of hydrodynamic instabilities at the interface between supersonic steam jet and water has given a new facet to the study of DCC. In the current study the equivalent von-Mises Stress, equivalent elastic strain and total deformation in the Perspex vessel that has been incurred due to the pressure stresses has been studied. These pressure stresses have been generated due to the condensing supersonic steam jet induced hydrodynamic instabilities. It has been investigated first by experimentally observing the temperature fluctuations in axial and radial directions across supersonic steam jet which actually depicts these instabilities. Then Direct Contact Condensation (DCC) model has been used to conduct the CFD study using a commercial code Ansys®. Accompanied with this a mock up study has been done in which the pressure loads computed using DCC model have been coupled to the Perspex vessel structure using one way Fluid Structure Interaction (FSI) analysis in Ansys® to compute the true scale equivalent von-Mises Stress, equivalent elastic strain and total deformation generated by hydrodynamic instabilities induced pressure stresses. On true scale, hundreds of Pico scale deformation has been computed in the Perspex vessel confinement

Spray characteristics of charge injection electrostatic atomizers with small-orifice diameters

Here the characteristics of charged sprays of insulating liquids generated by an improved charge injection (electrostatic) atomizer design are described, and the experimental database previously available in the literature is extended to a smaller range of orifice diameters and to more viscous liquids. Previously identified “subcritical” and “supercritical” electrohydrodynamic (EHD) regimes for the atomizer are confirmed to be present for the viscosity and orifice diameter ranges studied here, showing that these EHD regimes appear to be generic to the atomization method. The jet breakup dynamics and length are qualitatively and quantitatively studied using imaging and phase Doppler anemometry (PDA), and the general spray plume characteristics are quantitatively described in terms of droplet velocity and diameter probability density functions (PDFs). Radial spray charge and mass flow rates are quantified as using a purpose-built collecting system. By appropriately normalizing the data, the degree of self-similarity between different spray data sets is clearly evident and proves that the near-axis droplets are poorly charged and that the mean specific charge increases with radial displacement, again in a self-similar manner

Electrical performance of charge injection atomizers

The parametric evaluation of the variables that define the operation of a charge injection electrostatic atomizer is described in terms of the electrical performance. Here atomizer performance for smaller orifice diameters and more viscous liquids than previously investigated is presented. The response of the injected current as a function of atomizer geometry, coupled to an analysis of the empirical charge injection laws, is used to relate the electrohydrodynamics with more well-established studies in quiescent liquid. Evaluation of spray and leakage current to injection current ratios are also used to determine the electrical efficiency with a view to locating the optimum operating conditions as a function of atomizer geometry and applied bulk flow. The optimum electrode-to-orifice diameter ratio in previous work is confirmed, and the relationship between the spray specific charge and the maximum electric field on jet surface at a critical point of operation is extended to charge injection atomizers of small orifice diameter

Estimation of the diameter–charge distribution in polydisperse electrically charged sprays of electrically insulating liquids

The majority of scientific and industrial electricalspray applications make use of sprays that contain arange of drop diameters. Indirect evidence suggests themean drop diameter and the mean drop charge level areusually correlated. In addition, within each drop diameterclass there is every reason to suspect a distribution ofcharge levels exist for a particular drop diameter class. This paper presents an experimental method that uses the jointPDF of drop velocity and diameter, obtained from phaseDoppler anemometry measurements, and directly obtainedspatially resolved distributions of the mass and charge fluxto obtain a drop diameter and charge frequency distribution.The method is demonstrated using several data-setsobtained from experimental measurements of steady polydispersesprays of an electrically insulating liquid producedwith the charge injection technique. The space chargerepulsion in the spray plume produces a hollow cone spraystructure. In addition an approximate self-similarity isobserved, with the maximum radial mass and charge flowoccurring at r/d * 200. The charge flux profile is slightlyoffset from the mass flux profile, and this gives directevidence that the spray specific charge increases fromapproximately 20% of the bulk mean spray specific chargeon the spray axis to approximately 200% of the bulk meanspecific charge in the periphery of the spray. The resultsfrom the drop charge estimation model suggest a complexpicture of the correlation between drop charge and dropdiameter, with spray specific charge, injection velocity andorifice diameter all contributing to the shape of the dropdiameter–charge distribution. Mean drop charge as afunction of the Rayleigh limit is approximately 0.2, and isinvariant with drop diameter and also across the spraycases tested

Phase Change and Corrosion Effect on the Performance of a High Voltage Transmission Conductor

High voltage transmission conductors used worldwide are produced in several configurations. One such configuration is composed of 26 aluminum spiral shaped strands placed at the outer ring and 7 steel strands which are supposed to hold the weight of the conductor, at the inside of the aluminium strands. The present work investigates the effect of time, temperature fluctuations and weather on the properties of such a conductor, over a long period of time (over 25 years). The temperature and load fluctuations create stresses due to expansion and contraction and the protective coating disintegrates due to the friction between the surfaces of the strands. It is also observed that a gradual reduction in diameter exists approaching the failure point which is attributed to the third stage of creep. X ray studies reveal oxidation and a change in grain size which supports the existence of creep. The conductor performance is deteriorated due to a combined effect of corrosion, disintegration of protective coating, reduction in diameter, increase in temperature due to high load and the resulting thermal stresses