Volume 6 Issue 1
Authors: P. D. C. Kumara; S. K. K. Suraweera; H. H. E. Jayaweera; T. R. Ariyaratne; A.M. Muzathik
Abstract: Comparison of material usage and cost of two types of cross-flow steam condensers is reported in this study which can be used for water desalination in conjunction with a parabolic trough solar energy concentrator plant. Traditional shell and tube condensers (where steam flows inside the tubes) and surface condensers (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 dimensions 4.5 m × 4.8 m with an aperture area of 21.6 m2 was 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, assuming solar irradiance to be 0.9 kW m-2 and the efficiency of solar energy harnessing system as 50% if the sun is available for four hours. The cooling water input temperature was assumed to be 30 °C. The minimum length required for a SS 304 tube of Ø 9.5 mm was 7.16 m for the traditional condenser and 1.30 m for the surface condenser. The efficiency of the traditional condenser reduced due to the formation of a condensed water layer on the surface of the tube, as it acts as a thermal barrier. However, in the surface condenser, efficiency was enhanced due to easy condensation while increasing the system pressure. Further, efficiency is enhanced due to density separation of wet vapour by changing the flow direction near the wet sump. Fabrication cost and maintenance cost are also found to be less in the surface condenser. As such, it can be concluded that use of surface condenser is the most cost effective method, which uses a smaller amount of material making the condenser smaller and lighter.
Keywords: Heat exchanger; Parabolic trough concentrator; Steam condenser; Steam condensing methods; Surface condensation; Water desalination
Authors: Angel Valerio; Michele Mossman; Deborah Henderson; Lorne Whitehead
Abstract: Greenhouse structures are widely used to enable sheltered plant growth. However, traditional transparent greenhouse structures are generally only used in moderate climates because the cost of the energy required for heating in cold climates is prohibitively high. This paper describes a new approach to the design trade-off between light transmission and thermal insulation in greenhouse structures. Here, a low power variable insulation system combining sunlight-concentrating structures and low cost thermal insulation is shown to be a potentially practical solution. Experimental devices have achieved thermal insulation values exceeding 3.33 m2K/W (compared to 0.42 m2K/W for triple layer polycarbonate greenhouses) while also maintaining light transmittance values greater than 70%.
Keywords: Variable Thermal Insulation; Compound Parabolic Concentrator; Light Valve; Cold Climate Greenhouses
Authors: Sankar Shanmugasundaram; Praveen Maruthur; Manivarma Kumaresan; Abhilash O. P; Akhil Das K; Abdul Maluf
Abstract: This paper discusses a detailed study on the performance of a SI engine fuelled with camphor-ethanol-petrol blends. In this study, a mixture consists of camphor and ethanol in weight percentage (20:80) was blended with petrol in three different ratios: 10%, 20% and 30%. A performance test was conducted in the SI engine at constant speed with varying torque using an eddy current dynamometer in order to evaluate the performance between the blended fuel and the sole fuel, such as brake power, specific fuel consumption, brake thermal efficiency and volumetric efficiency, among others. The study also includes viscosity measurements from a redwood viscometer, Calorific value measurements from a bomb calorimeter, density calculations and exhaust emission tests in a four gas analyser for both blended fuels as well as for pure petrol. It is inferred from the study that lesser specific fuel consumption, less emissions due to complete combustion of air fuel mixture and maximum volumetric efficiency were achieved in the blended fuel that results in efficient working of the spark ignition engine with less pollution. The main objective of this study is to increase the performance of SI engines, to reduce the emission rate and minimize the specific fuel consumption with the blended fuel to make the planet greener.
Keywords: Camphor and ethanol mixture; Petrol; Spark ignition engine; Performance test; Exhaust emission test