ABSTRACT:

This work reports a design and construction of a drying chamber powered by parabolic trough solar concentrator. The construc ted drying chamber is made of thin aluminum sheet material with two compartments; one is fo r installation of standby electrica l heaters and the other is for material pallet. The chamber is powered by a para bolic trough solar concen trator with aperture area of 5 m 2 . An electrical heater backup was employed to maintain the temperature inside the chamber at a given constant temperature when solar energy is not sufficient. The maximum variation of the temperature insi de the chamber along the length of the material pallet was found to be 8 °C when the chamber is powered by sola r concentrator. This va riation was 16 °C when the chamber is powered by electric heaters. Temper ature variation across the vertical direction is almost constant when the chamber is empty and a 10 % drop in temperature was observed over the material pallet relative to the other areas. The drying characteristics of samples of cabbage, boiled rice, scraped coconut, dry le aves and grass for different te mperatures obtained using the drying chamber are found to be fitted well with the page mode l and the corresponding drying constants at 80 °C are found to be 0.0197, 0.0139, 0.0319, 0.0296, 0.0564 respectively.

Viraj M.P.S., Kumara P.D.C., Jayaweera H.H.E. and Ariyaratne T.R (2016). “Feasibility study on constructing a heat battery for parabolic trough solar thermal energy plant”. Research Symposium – University of Colombo. Colombo, Sri Lanka.

Kumara P.D.C., Viraj M.P.S., Jayaweera H.H.E., Muzathik A.M. and Ariyaratne T.R. (2016). “Experimental investigation of the temperature dependency of the thermal conductivity of glass wool used in a steam generator”. Research Symposium 2016 – University of Colombo. Colombo, Sri Lanka.

ABSTRACT:

II today’s world. Higher level of nutrients is one of the indicators, that claims a water sample is polluted. The population of phytoplankton (a green color algae), is higher in such water samples. Chlorophyll is universally used as an indicator of phytoplankton biomass. Therefore by measuring the level of chlorophyll, it is possible to make

Jayakodi, J.D.M., Kumara, P.D.C., Ratnayake, J.K., Jayaweera, H.H.E. & Ariyaratne, T. R. (2015) Theoretical study of performance of a cross flow steam condenser, Research Symposium – University of Colombo.Colombo, Sri Lanka.

ABSTRACT:

Development and testing of an optical technique for evaluating the shape of reflective parabolic trough is reported. This method consists of a single axis rotatable He-Ne laser with a vernier scale and a target plane with a millimeter scale. The parabolic reflector is scanned by the laser beam vertically with known angles and the positions of the reflected beam hit on the target plane are recorded. The deformed angle of the reflective surface is then calculated using these data and the variation of the focal length is finally derived. The surface quality of a prototype Parabolic Tough Concentrator (PTC) was evaluated using this technique at three different positions along the reflector, the testing method developed found to be acceptable as it produced consistent data over different locations of surface. Deviations up to 90 mm in the focal length were detected using the method and the results revealed that the shape of the parabola of this PTC was significantly deformed in the first quarter of the vertical direction of the shape and the other part is of the acceptable level in view of the large acceptance angle of the Heat Collecting Element (HCE).

Tennahewa, T. H., Udeshi, K.M.W. & Jayaweera, H.H.E. (2015) Laser diode-based chlorophyll sensor, Research Symposium – University of Colombo.Colombo, Sri Lanka.

ABSTRACT:

The relation between diffused reflectance (in spatial and in spectral domains), soluble solid content and firmness of “Mauritius” variety of pineapple (Ananas comosus) grown in Labuduwa farm, Galle, Sri Lanka together with the shelf-life have been studied for estimating the physiological maturity of them. It is found that there is no significant variation in the firmness with the shelf-life. The soluble solid content shows a linear relationship with respect the shelf-life for this sample of size ten with a coefficient of determinant (R2) of 0.87. Diffused reflectance measured using an RGB web camera with the help of two linear polarisers and converted into the spherical coordinate system and two-dimensional histograms were plotted considering the zenith and azimuth angles. It is found that the peak of the two-dimensional histograms follows similar paths and converged to the same region for all pineapple in the sample with the shelf life. Also, it is found that the average colour (by considering each pixel) ratio of red to green show a linear relationship with the soluble solid content (R2=0.1255) and shelf life (R2=0.6929).

ABSTRACT:

Theoretical comparison of material usage and cost of two types of cross-flow steam condensers that can be used for water desalination in conjunction with a parabolic trough solar energy concentrator type plant (PTC) is reported. Traditional shell and tube condenser (steam flows inside the tubes) and surface condenser where steam flows in the shell and cooling water flows in the tubes are considered in this study. It has been found that the energy production from the PTC of dimension 4.5 m× 4.8 m with the aperture area of 21.6 m 2 is 19.4 kW. It has been calculated that the distilled water production capacity of the solar energy harnessing system per day is 55.6 l by assuming solar irradiance as 0.9 kW m-2 and the efficiency of solar energy harnessing system is 50% if the sun is available for four hours. The cooling water input temperature was assumed as 30 C, the minimum length required for a SS 304 tube ofis 7.16 m for the traditional condenser and 1.30 m for the surface condenser.

Viraj, M.P.S., Suraweera, S.K.K., Kumara, P.D.C., Pattividana, A.N., Jayaweera, H.H.E. & Ariyaratne, T. R. (2015) Controlling of a parabolic trough concentrator (PTC) for tracking sun by implementing sun algorithm on a microcontroller, Research Symposium – University of Colombo.University of Colombo, Colombo, Sri Lanka.

Kumara, P.D.C., Suraweera, S.K.K., Jayaweera, H.H.E., Muzathik, A.M. & Ariyaratne, T. R. (2013) Wind load analysis for structural design of a parabolic trough concentrator, Research Symposium – University of Colombo.Colombo, Sri Lanka.

ABSTRACT:

Development and testing of an optical technique for evaluating the shape of reflective parabolic trough is reported. This method consists of a single axis rotatable He-Ne laser with a vernier scale and a target plane with a millimeter scale. The parabolic reflector is scanned by the laser beam vertically with known angles and the positions of the reflected beam hit on the target plane are recorded. The deformed angle of the reflective surface is then calculated using these data and the variation of the focal length is finally derived. The surface quality of a prototype Parabolic Tough Concentrator (PTC) was evaluated using this technique at three different positions along the reflector, the testing method developed found to be acceptable as it produced consistent data over different locations of surface. Deviations up to 90 mm in the focal length were detected using the method and the results revealed that the shape of the parabola of this PTC was significantly deformed in the first quarter of the vertical direction of the shape and the other part is of the acceptable level in view of the large acceptance angle of the Heat Collecting Element (HCE).

Ranatunga, C. L., Jayaweera, H. H. E. & Ariyaratne, T. R., (2010) Vibration effects on the quality of tomatoes. Research Symposium – University of Colombo. Colombo, Sri Lanka.

ABSTRACT:

A non-destructive image analysis method for classification of tomato (Lycopersicon esculentum) varieties (Sri Lankan hybrids) has been developed. Maheshi, Rajitha, T245 and Thilina varieties grown in Atipola, Sri Lanka during Yala season, 2009 were used in the study. Multispectral imaging system with white LEDs as light source was used for data acquisition. Two plane polarizers have been employed in order to acquire multiple scattered light coming from the interior of the sample. The acquired data were corrected for intensity variations occurred due to the 3-dimensional nature of objects by transferring them to 2-dimensional images. The 2-dimensional data were subsequently transformed into a 1-dimentional array in order for efficient computer processing. The acquired data were compressed using singular value decomposition and trained them with a linear model with an offset. After successful training of …

Wattage, S. C., Ariyadewa, P. D. & Jayaweera, H. H. E., (2009) Development of server room monitoring and alarming system based on Global System for Mobile communication (GSM). 65th Annual Technical Sessions.University of Kelaniya, Kelaniya, Sri Lanka – Association for Advancement of Science.

Shyamali, A. K., Jayaweera, H. H. E. & Ariyaratne, T. R., (2008) Study of density of local paddy varieties. 64th Annual Technical Sessions.University of Colombo, Colombo, Sri Lanka – Association for Advancement of Science.

Ariyaratne, T. R., Jayaweera, H. H. E. & Randunu, R. P. N., (2008) Realization of deep-frying condition with a lesser quantity of oil. Research Symposium – University of Colombo. Colombo, Sri Lanka.

ABSTRACT:

Tomato (Lycopersicum esculentum) is a delicate horticultural crop grown in many areas in Sri Lanka. Most of the tomato farms are situated away from main roads. Often tomato collecting trucks have to cross potholes, kerbs, bumps and even causeways. Vertical vibration acceleration experienced by tomatoes during transportation contributes towards increased post-harvest losses. It causes shortening of their shelf life. Objective of this study is to identify and estimate the key parameters leading to losses due to vibration at vehicular road transportation. A tri-axial accelerometer (Steval LIS 302 DL) has been used in this study to detect and record the vibration acceleration. Energy associated with the vibration was estimated in terms of the power spectral density (PSD). At poor road conditions (having higher IRI values) and at higher truck speeds the generated vertical vibration levels are higher and the resulting …

Lelwala, R., Abeysekara, A. U., Indunil, B. A., Ariyaratne, T. R. & Jayaweera, H. H. E., (2008) Method of operation of the ‘voting panel’ of the electronic voting machine for presidential elections in Sri Lanka. Research Symposium – University of Colombo. Colombo, Sri Lanka.

ABSTRACT:

Thin-layer drying characteristics of paddy were examined within the relative humidity range from 30% to 60%. A test chamber has been constructed with Perspex and continuously flushed with low humid air to control the inside relative humidly at required levels and several homogeneous thin layer paddy samples were dried inside the chamber. BG 300, BG 352 and BG 357 paddy varieties developed by Rice Research and Development Institute, Bathalegoda, Sri Lanka have been used in this study. Normalized drying data was transformed into dimensionless parameter called Moisture Ratio, and fitted with four semi-theore tical models. Correlation coefficients, standard errors and residual plots were used as criteria for evaluating the goodnes s-of-fit. Of the models used the two-term exponential model was found to fit well with the experimental data and is recommended as the thin-layer drying model for paddy.