Applied Mechanics and Materials Vols. 592-594

Abstract: Under optimum environmental conditions, microalgae are able to accumulate significant amounts of lipids within diminutive span. They are therefore established as promising candidates for the production of biodiesel. In order to develop this, and also to cut down the cost parameter involving the production of biodiesel from algae, the growth rate of algae has to be enhanced. To maintain the proper condition for their growth, closed cultivation is the best option for which different types of reactor are used. Bubble column reactor, is one among them, where the mixing rate of algae with nutrients, growth rate increases. This paper reported the design modification of spiral column reactor which will have better mixing rate than conventional bubble column reactor in turn more mass transfer due to more turbulence which can be seen by analyzing the turbulence kinetic energy against radius for both the reactors, for that CFX solver is been used.

Abstract: Vegetable oils are considered as substitute for energy production. In this paper, a correlation was developed based on iodine and saponification values of the waste frying oil to estimate its higher heating value. Five samples of waste frying oil were collected, its iodine value and saponification value were measured and the heating values were measured. A correlation by linear regression method was developed and compared with the heating value obtained experimentally. A Comparison was made with other correlations available in the literature. The comparison of higher heating value obtained from new correlation and experiments gave a R² value of 0.97, error of standard deviation is 0.06 and an average error of 1.86%.

Abstract: The Performance of a thermal system is generally analysed by carrying out energy and exergy analysis of its different subsystems. In the present study the performance of subsystem namely PDC, receiver plate and PDC in a system of solar parabolic dish thermoelectric generator is studied. It is found that the energy and exergy loss are minimum in the receiver plate as compared to PDC and thermoelectric generator (TEG) at a particular direct normal irradiation (DNI). The exergy and energy efficiency in the PDC and TEG increase with increase in concentration ratio.

Abstract: The present study involves the preparation and characterization of the biomass briquettes made from saw dust and rice husk. Five samples with different compositions were prepared using the old news papers as the binder for both the biomass. Ultimate analysis, proximate analysis, heating value and handling characteristic of all the samples were determined. It was observed that the compositions of the biomass sawdust (BMS)-15 and biomass rice husk (BMR)-15 are suitable for the downdraft gasifier.

Abstract: Buildings account for approximately 40% of the global energy consumption and 36% of total carbon dioxide emissions. At present many efforts are underway to reduce energy consumption and carbon footprint of buildings by optimizing their performance. Building envelope elements have a major impact on the performance of buildings. However, the best combination of the building envelope elements for optimizing the performance of buildings is difficult to determine and is not known. Building performance analysis is mostly done through energy modelling by using a whole building simulation tool. However, this is a slow and a tedious process, and generally only a few cases are evaluated in a large range of possible scenarios. By combining a generic optimization scheme with energy modelling, the best combination of building envelope elements can be determined and, thereby, it is possible to optimize the performance of buildings successfully subject to predefined constraints. This paper describes how the performance of an office building located in the suburbs of Colombo, Sri Lanka is optimized in terms of building envelope elements through combined energy modelling and generic optimization. The optimized envelope design with its efficient utilization of daylight, not only reduces the annual energy consumption substantially, but also leads to better thermal comfort for the occupants.

Abstract: — Active noise control is used to reduce low frequency noises. A hybrid ANC structure combines feedforward and feedback structure to generate an anti-noise wave, which results in high performance in control of unwanted noise. In this paper, a hybrid structure for active noise control (ANC) is developed. The hybrid structure utilises a variable step size LMS algorithm for faster convergence. This structure also incorporates variable step size (VSS) online secondary path modelling, the white noise injection is stopped at the optimum point when the modelling accuracy is sufficient. Comparative simulation results shown in this paper indicate the effectiveness of the proposed approach in reducing acoustic noises.

Abstract: This paper compares two different accident sequence methodologies for external flood probabilistic safety analysis (EFPSA). It is shown that the two methodologies lead to identical expression for CDF with an example. Using accident sequences developed for internal events PSA is recommended for detailed external flood probabilistic safety analysis of prototype fast breeder reactor.

Abstract: — The performance of an ANC system depends on the convergence factor. A suitable value of convergence coefficient is extremely important as it impacts both the speed of convergence and the stability of the adaptive algorithm. Traditionally, in active noise control systems fixed convergence factor is used. In this paper, a novel approach of time-varying convergence factor μ is used and the results are compared with traditional feedforward and feedback noise control systems. This algorithm leads to faster convergence and provides reduced mean-squared error compared to the conventional fixed parameter algorithm.

Abstract: Chlorine is highly toxic and an accidental release of chlorine has the potential to kill or cause injury to people. This kind of release may occur unexpectedly and cause huge loss. Hence, proper mitigation methods should be devised to tackle them effectively. In this study, an accidental release of liquid chlorine from the storage tank is considered and a new mitigation model for the effects of release is proposed. A provision to recover the leaked chlorine is also proposed in the mitigation system. This approach can be beneficial to understand the significant elements of mitigation system and serve as a reference to various emergency response and design practitioners.

Abstract: PVC insulation has extensively been used for insulating low voltage electrical cables. They offer superior insulating properties but how ageing and exposure could affect their insulation properties is a matter of concern. Chemical exposure related failure modes are known but have received only limited study. The traditional testing methods like insulation testing could only test whether the present properties are satisfactory. The application of thermal analysis methods like differential scanning calorimetry could identify the variation in thermal characteristics with respect to ageing and chemical exposure. Polluted environments may cause a direct attack upon a polymer. It has been concluded that significant changes in the behavior of insulation occurs in acidic environment that may lead to insulation failures.