S.I. Gilani

Hourly Solar Radiation Estimation Using Ambient Temperature and Relative Humidity Data

This paper presents hourly solar radiation estimation methods using ambient temperature and relative humidity data. The methods are based on the decomposition model that is calculating each of solar radiation components, which depend on atmospheric transmittance. Two methods to predict atmospheric transmittance value using available meteorological data were proposed. In the first method, a decision matrix was used, while in the second method, regression correlation of meteorological parameters was used. The calculations results were evaluated using statistical parameter. Though the result shows both of the methods perform well, more satisfactory results were obtained from first method with Root Mean Square Error of 87.6 Watt/m 2 , Normalized Root Mean Square Error of 8.29%, correlation coefficient of 0.95 and index of agreement of 0.97. Furthermore, the first method only needs ambient temperature and relative humidity data that commonly measured in meteorological stations.

A Review of Solar Air Heater for Drying of Agricultural Products

Bulk of farm products need to be preserved because of their perishable nature. The cheapest and environmental friendly means is indirect usage of solar irradiance to reduce the moisture content of these products to a level that cannot sustain the activities of micro-organisms. The research on solar collector has gained its popularity over the years due to mans quest for green energy which has led to increase in demand for the utilization of solar energy. Harnessing of solar energy by man for drying purposes was predominantly by direct method which reduces the quality and quantity of the dried products. This work presents the most recent contributions on solar air heater of flat plate absorber category. Various models, material of component parts and performance efficiency of these air heaters were discussed and there is need for collector optimization. The study was concluded with a focus on multiple pass approach of solar harvesting.

Performance Evaluation of a Variable Geometry Gas Turbine in a CHP Plant

This study is to develop mathematical models and evaluate the performance of a gas turbine with variable geometry compressor working in a CHP plant. A single shaft gas turbine plant can maintain the exhaust gas temperature if the load is not below 50 % of the full load by simultaneously regulating the compressor variable vanes position and fuel flow. For load less than 50% the engine is running to meet the power demand. This is achieved by controlling the fuel flow and air bleed at the downstream of the compressor to avoid surge formation while variable vanes are opened fully. To accommodate change of compressor parameters during variable vanes re-stagger correction coefficients are introduced. A behavior of a 4.2 MW gas turbine performance was evaluated. The effect of variation of load and ambient temperature on the gas turbine specific fuel consumption, temperature, pressure ratio, variable vanes opening and efficiency were examined. Comparison between the field data and simulation results demonstrate good agreement. The off-design calculation was done by in-house developed program in MATLAB environment.

Design and Simulation of Small Heliostat Field at Universiti Teknologi PETRONAS Campus

Solar Power Tower systems have attracted the worldwide interest since the early 1980s and heliostat fields have been an area for development due to their high cost and important function. This paper presents a mathematical model to design a small heliostat field with 3 dual-axis heliostat units located in Universiti Teknologi PETRONAS, Malaysia. The model mainly relies on the sun position and tower and heliostat geometrical relations, namely, tower height and the ground distance of the concerned heliostats. The heliostat field layout is configured according to radial staggered pattern then varying the tower height and heliostat ground distance to calculate the facing and target angle of each heliostat. TRNSYS software was used to simulate the power output for the proposed heliostat field. The modeled heliostat field could deliver 10 kW for 12.4 m2 reflective area for latitude 4.3̊ N. A solar power tower testing facility will be built according to the design specifications produced in this paper and TRNSYS simulation results are required to estimate the power input to the receiver system for sizing purpose in the future.

Investigation of Evacuated Tube Collector Performance at High Temperature Mode Using TRNSYS Simulation Model

It has been proved that creation of vacuum between the absorber and the cover of a solar collector is resulting in a substantial improvement in the collector efficiency due to reduction in the heat loss through convection ad conduction. In this work, the performance of evacuated tube collectors is investigated using TRNSYS simulation model. Different levels of concentrations have been considered in the simulation to predict the power generation. The simulation results showed that the thermal performance of evacuated tube collectors with high concentration ratio can provide a good improvement to the receiver output.

Lumped Components Modeling of Double Pass Solar Collector with Porous Matrixes

In this report, the modeling and simulation of a double pass solar air absorber was carried out using combination of Simscape and Simulink modeling tools. The solar system air mass flow rate and the porous media were critically investigated by using local weather data of Seri Iskandar, Perak, Malaysia. Optimal inlet air flow rate of 0.034kgm-2s-1 was obtained and one of the packed beds, sandstone extended the thermal transfer period of solar collector system by 1150s which displayed good agreement with the reported model and experimental outcomes. The results obtained have shown that it is a promising alternative tool for solar thermal experimentation modeling.