Two phase pressure drop characteristics in a horizontal smooth pipe refrigeration ammonia (R717) system

This paper focused on comparison of pressure drop characteristics verses the vapour qualities and modeled of ammonia refrigeration system using the results of experiments and simulation results in a virtual environment. In this study two-phase ammonia fluid flow system with mass fluxes from 50 to 100 kg/s.m2, vapour qualities between 0 and 1, and saturation temperatures from -20oC to 30oC were considered. The single-phase pressure drop equation with a modified fluid density was used to predict the two-phase pressure drop of the system. The results indicate that two phase pressure drop is dependent upon the average kinetic energy density of the flow, hydraulic diameter and friction factor of the pipe

Potential of global solar radiation in Terengganu, Maalaysia

Accurate information on the intensity of solar radiation at a given location is essential to the development of solar energybased projects. This information is used in the design of a project, in cost analysis, and in calculations on the efficiency of a project. As the solar radiation data are not available for most areas in Malaysia, this study is crucial in establishing the solar data for Terengganu, Malaysia. The geographical co-ordinates of the site are 50 10’ N latitude 1030 06’ E longitude and 5.2 m altitude. The data used in the present study were collected from the Renewable Energy Station, University Malaysia Terengganu from 2004 to 2010. In addition to these data, secondary data were obtained from Malaysian Meteorological Department from 2004 to 2009 at the Terengganu Airport station (5o 10.0’ N latitude 103o 6.0’ E longitude) which is nearly 2 km southeast to the study area. From the raw data, the mean, maximum and minimum hourly values were calculated. The highest 24 hours basis daily and monthly mean global solar radiation values were 314.9 W/m2 and 7556 Wh/m2/day, respectively. The highest hourly average solar radiation intensity was 1139 W/m2 during this study period. Yearly average daily solar energy was 18.93 MJ/m2/day. Besides the global solar radiation, the clearness indexes and air temperature variation are discussed. This study indicates that Terengganu state has a strong solar energy potential

Photovoltaic modules operating temperature estimation using a simple correlation

The operating cell temperatures of photovoltaic (PV) modules directly affect the performance of the PV system. In this study, an effective new approach for estimating the operating temperature of a photovoltaic module is presented. The developed model is simple and does not need any complicated calculations. The proposed approach uses a simple formula to derive the PV cell temperature from the environmental variables such as ambient temperature, irradiance and wind speed. Effectiveness of the new temperature estimation procedure is investigated through some conducted simulations in MATLAB/Simulink environment and its validity is verified by experiment on a UNI-SOLAR US-64 solar photovoltaic modules. It was found that, in general, the model tends to give better results of temperature prediction. From the results, the predicted PV cell temperatures show a good correlation with the measured data. The MBE, NMBE, RMSE, NRMSE and correlation coefficient of predicted and measured PV cell temperatures are -0.3490 oC,-0.7328%, 1.3571 oC, 2.8492% and 0.9763, respectively. The statistical results show that the model can be used to predict the PV cell temperatures with an error of less than 3%. As a conclusion, the PV cell temperatures can be estimated using a new linear model based on the steady state approach prediction as Tmod uleo C 0.943 Tambient 0.0195 Irradiance 1.528WindSpeed 0.3529

Defects analysis, minimize metal wastages and yield improvement for grey cast iron casting: a case study

Proper selection and maintenance of melting and holding equipment, molten metal wastages, moulding methods and casting defects influence metal losses in foundry. Casting yield mainly depends on runner and riser weight, pouring practices and casting defects. In this study all castings were grouped into three categories namely light, medium and heavy weight castings. After implementing new runners and risers and remedial measures for defects in castings, weights of runners and risers have reduced by 2.1%, 5.7% and 3.1% respectively for the three categories. Weights of defects in castings have been reduced by 1.6%, 6% and 1% and as a result casting yield has increased by 3.5%, 7.7% and 4.2% from products of light, medium and heavy respectively. 2014 Trade Science Inc. - INDI

The relationship between corrosion rate of aluminum (AA 5083) and supply electric voltage in seawater

In this paper effect of electric voltage level on corrosion rate of Aluminum (AA 5083) was studied. Eighty samples plate surfaces were prepared according to the standard procedure. The corrosion studies have been carried out at room temperature using seawater. Various level of electric DC voltage (0, 1.5, 3 and 4.5 V) applied and samples were left for 10, 20, 30 and 40 days in order to determine its corrosion rate for each and every level of voltages supplied. These samples were analyzed to determine the weight loss, electrochemical test using Electrochemical Impedance Spectroscopy and morphology test to determine the corrosion rate of the Aluminium plate and effect of voltage levels. After 40 days, the final weights of all samples were differed compare to the initial weights. For 0 V sample initial and final weights were4.7375 g and 4.7164 g respectively, which is 99.7% of its initial weight. For 1.5 V sample, initial weight was 4.7262 g and final weight was 3.8833 g, which is 82.4% of its initial weight. Meanwhile, for samples of 3 V and 4.5 V, initial weights were 4.7225 g and 4.7511 g respectively, after 40 days; samples were loosed 1.3025 g and 1.5169 g respectively. The results reviled that electric voltage is one of the factor that can accelerate corrosion of Aluminium AA 5083 in seawater. Further, results indicated that introduction of electric voltage obviously maximize weight losses and enhance Aluminium dissolution in seawater. As a conclusion from this study, corrosion rate of Aluminium AA 5083 plate is increasing by increasing of DC electric voltage in seawater. 2013 Trade Science Inc. - INDI

Effect of boron on friction and temperature characteristics of brake pad materials

Friction material in a brake system plays an important role for effective and safe brake performance. Brake materials contain mainlyAlumina and other ingredients. This research attempts to examine mechanical properties of Boron mixed brake pads. Five groups of semi-metallic composite materials were studied. Friction coefficient of Boron mixed and commercial brake pads were significantly different.Average friction coefficient of Boron mixed pads was 0.495, 0.065 higher than commercial pad. Abrupt reduction of friction coefficient which is known as fade was more significant in the commercial pad samples than in Boron mixed pads. Fade occurred in commercial pad sample at the lower temperature as first fade was at 204oC and second was at 159oC resulted from earlier softening and degradation of Alumina material. All Boron pads were more stable and constant than their commercial counterparts. The study shows a slight reduction of friction coefficient at a temperature of 204oC during the first fade and 238oC on the second for Boron mixed pads. Both commercial and Boron mixed brake pads showed normal recovery stage in that they returned to their pre-fade friction coefficient levels with little temperature reduction. Properties of Boron mixed brake pads are better than Commercial brake pads. 2013 Trade Science Inc. - INDI

The potential of a small scale environmentally friendly renewable hybrid photovoltaic and wind energy generation system at Terengganu state coastal area

This paper presents a study of data on solar radiation and wind resources used to generate the renewable electrical power in the Terengganu state coastal area. This study utilized the data collected from the University Malaysia Terengganu Renewable Energy Research Station (UMTRERS) and Kuala Terengganu International Airport (KTIA) for years 2004, 2005 and 2006. The generated power analysis was conducted using MATLAB, based on the power produced from the Unisolar U.S 64 photovoltaic module with an area of 1 m2 and the BWC.XL wind turbine with a blade area of 4.9 m2. The statistical method of the Weibull distribution was used to analyze the wind data to determine the potential of wind energy. Moreover, extrapolation of the 23 m data, using the power law, was used to determine the wind data at heights of 30, 40, 60, 80, 100 and 120 m. A wind turbine with a capacity of 1 to 50 kW was used to estimate the power generated. Furthermore, a general study was implemented based on the power produced from both sources for supplying renewable electricity for the basic utilization of households in the Terengganu coastal area habitation. The results showed that the average annual energies from the photovoltaic module and wind turbine were 95.18 kWh/m2yr and 339.09 kWh/m2yr, respectively. In addition the ideal height for continuously powering a household was higher than 50 m for the wind turbine size of over 50 kW for the UMTRERS site

Estimation of global solar irradiation on horizontal and inclined surfaces based on the horizontal measurements

Solar radiation data are essential in the design of solar energy conversion devices. In this regard, empirical models were selected to estimate the global solar radiation on horizontal and inclined surfaces. The hourly solar radiation data measured at the study area during the period of 2004e2007, were used to calculate solar radiations using selected models. The selected models were compared on the basis of statistical methods. Based on the results, a new model, H/Ho ¼ 0.19490 þ 0.4771(n/N) þ 0.02994 exp(n/N) has been developed, based on Kadir Bakirci linear exponential model. This is highly recommended to estimate monthly mean daily global solar irradiation, on a horizontal surface. Further, a model to convert horizontal solar global radiation to that of radiation on a tilted surface is also presented. It is based upon a relatively simple model proposed by Olmo et al. which requires only measurements of horizontal solar radiation. The developed model appears to give excellent results and has the advantage of being relatively simple for applications. The present work will help to improve the state of knowledge of global solar radiation to the point where it has applications in the estimation of global solar radiation, both on horizontal and inclined surfaces

Oxidation stability of palm oil methyl ester (POME) as biodieseland its corrosiveness behavior

This research was conducted to study the oxidation stability of Palm Oil Methyl Ester (POME) as biodieseland its corrosiveness behavior. Aluminiumalloy was used to study corrosiveness behavior and tested using Electrochemical Impendence Spectroscopy. Biodiesel samples were tested to define their functional group by using Fourier Transform Infrared Spectroscopy. There wereonlyslight changes in weight of test samples and there was a decreased of corrosion rate.As conclusion, POME biodiesel prohibited and resists the corrosion attack on Aluminiumdue to formation of an oxide layer

Natural honey as corrosion resistant for Aluminium Alloy

The corrosion behaviour of AA6061 aluminium alloy in tropical seawater was investigated using weight loss measurement and electrochemical polarization technique. The electrochemical measurements showed that the presence of natural honey as corrosion resistant significantly decrease the corrosion current densities (icorr) and corrosion rates. It was observed that the inhibition efficiencies increased with the increasing concentrations of the resistant. Potentiodyanamic curves suggested that natural honey suppressed both cathodic and anodic processes. A good fit to Langmuir adsorption isotherm was obtained between the degree of surface coverage and the concentration of natural honey. It can be concluded that natural honey is an excellent corrosion resistant for aluminium alloy immersed in tropical seawater