Global Journal of Researches in Engineering, J: General Engineering, Volume 22 Issue 1

Analysis of Thermal and Optical Efficiency of Parabolic Concentrating System for Thermal Application lobal Journal of Researches in Engineering ( ) Volume XxXII Issue I Version I J G 54 Year 2022 © 2022 Global Journals receiving the highest reflected sunlight is gotten or through the calculations (equation) method. In this work, the calculation (equation) method which entails using the parabola equation to calculate the required parameter was adopted. Referring to fig 3.1, the focal point would be calculated using equation (8) below: (8) Step 1: The longest diameter (width) of the parabola up to its rim was measured to be 252m Fig.3.3: Schematic diagram for determining the focal point Step 2: Divide the diameter by two i.e. to determine the radius y, we have y = 126m Step 3: Square the radius i.e. Step 3: Measure the depth of the parabola (d) from its vertex .i.e. (42m) and multiply it by 4. i.e. = 4d (4*42) =168m Step 4: substituting into equation 23 gives the focal point i.e. a) Construction Procedure The main components of a Parabolic Dish Solar Concentrator (PDSC) are: The Parabolic dish, the Support and the Receiver, b) Solar Dish Concentrator Design The parabolic dish concentrator has six segmental parts for easier transportation to be assembled using bolts and nuts to tight them together. Each part would be made up of light steel material; the upper surface would be coated with an aluminium foil reflector sheet or thin foil reflective aluminum sheet in order to have a high efficiency of reflecting sun energy onto the receiver. After finishing the coating, the segmented part of the parabolic dish would be connected together to be fixed into the parabolic dish shape. The whole system would be mounted on a rigid sand- rooted support. Alternatively, Stainless steel sheet would be use as reflecting surface. The collector would be design using simple parabolic equations. From geometrical relations of the parabolic section, equations (1), the cross section for the parabolic concentrator would be trace as shown by figures. 3.1. The sheet would be curve to form a parabolic dish module of reasonable length and aperture width with effective aperture area. The simple parabolic equation as stated by [28] in line with equation (8) above c) The Receiver/Heat exchanger Design The receiver is the part of the system that converts solar radiation to heat energy in a working fluid. The receiver consists of an absorber, heat exchanger and possibly heat storage. Therefore, in this research work the heat exchanger would be inform of an improvise receiver in the form of a kettle-like form with an internal coil made from a good conducting material e.g. copper. It shall be used in conducting the steam generation test. The absorber would be in form of impinging surface for reflected solar radiation to strike. Radiation would be absorbed into the absorber material as heat. The heat exchanger transfers the energy to a working fluid that carries the energy out of the receiver. Equation (9) shows an energy balance for a receiver. (9) Where The receiver design for this research work would act as an absorber, boiler, and heat storage unit. A cavity type absorber (receiver type) is selected due to its high absorption efficiency and low heat loss. Surrounding the absorber inside the receiver would contain 10 kg of sodium nitrate. This salt will acts as a heat transfer and storage media and 0.6 cm diameter copper tubing would be coiled through it. The working fluid is pumped through the tubing where heat is transferred to the fluid. d) Collector supporting structure (Adjustable mechanism) For collectors' stability and accuracy, a rigid supporting structure would be designed, to structure the frame that would be supported for the rotation axis of the parabolic reflecting surface. It’s used for the rotation of the horizontal axis for daily tracking of the sun. For test purpose and cost reduction, the unit would be designed for easy manual tracking system as shown Fig 3.4 Fig. 3.4: Adjustable Tracking System where D is the longest width [28]. The steps are as follows