Advanced Materials Research Vol. 505

Abstract: Through the analysis of the glass wall and solar panel cleaning robot research status at home and abroad, based on cleaning characteristics and requirements of such kind of smooth surface, a full pneumatic-driven flat surface cleaning robot system is presented. The robot adopts unique three-position cylinder driving technique, SCM and PC two-level control, can crawl along the smooth surface and clean, and can overcome obstacles in a certain height. Running results show that the robot system has simple structure, low cost, the functions of on-line fault diagnosis, and can provide a new efficient, simple and safe way for the glass wall and solar panel cleaning.

Abstract: This paper deals with a formulation and analysis of dynamic mechanism for the folder type of automatic door extensively used in industrial plants. A nonlinear equation of motion is derived in terms of folding angle to estimate driving forces. An operating time needed to open the door and corresponding velocities are controlled for the purpose of design. The stiffness of torsional spring is also investigated when the automatic door is closed to prevent the free falling. This research includes a numerical experiment for the two-step folding automatic door which results from the analysis methodology for this multi-step folding mechanical system.

Abstract: In order to reveal the science of adding winglet for Active aircraft, the paper calculates the aerodynamic efficiency of a wing added winglet using CFD technology, Aerodynamic benefit of the wing added winglet reaches the maximum when the angle of attack is 2 degree, the lift and drag reduction rate are 21.07% and 43.56% respectively. The results show that it is a good choice to add winglet for aircraft to reduce operation cost and fuel consumption.

Abstract: By tangent and normal use of the circle scroll coordinate system is defined. Through regular, long pieces, short pieces of involute (evolute) process analysis, a range of involute (evolute) transformation model is established to achieve the high degree unity of a rectangular coordinate curves and polar coordinates (rotation) curve. For the practical application of engineering technology, the paper presented a method of continuous circular gear tooth profile curve, non-circular section of the conjugate gear involute curve rate curve for the rectangular coordinate, providing an effective way for the research of the rotation curve and the design of gear transmission.

Abstract: Damping in built-up structures is produced by the energy dissipation due to micro-slip along the frictional interfaces. A finite element model of the linear elastic system has been formulated using the Euler-Bernoulli beam theory to investigate the damping phenomena in riveted connections. The discrete element system having two degrees of freedom per node representing v and has been used for the analysis. The generalized stiffness and mass matrices for this element has been derived. Extensive experiments have been conducted for the validation of the analysis. From this study, it is established that the damping capacity increases and the natural frequency decreases due to the joint effects.

Abstract: In this study, the dynamic response of a discrete system being fixed to an elastic beam has been controlled actively by means of a feedforward control method. A discrete system is considered as a vibrating receiver which be forced to vibrate by a vibrating source being positioned on the elastic beam. By analyzing the interactive motions between a discrete system and an elastic beam, the equation of motion for an elastic beam was derived by using a method of variation of parameters and also dynamic response of a discrete system was solved. To define the optimal conditions of a controller, the cost function, which denotes the dynamic response of a discrete system was evaluated numerically. The possibility of reduction of a dynamic response was found to depend on the locations of a control force, the magnitude of a discrete system mass and a forcing frequency.

Abstract: In this paper thermodynamic performance of a combined heat and power cogeneration system driven by low-temperature source is investigated. The system consists of regenerative Organic Rankine Cycle (ORC) and an additional process heater as a series circuit. Seven working fluids of isobutene, butane, R11, R123, isopentane, normal pentane, and R113 are considered in this work. Special attention is paid to the effects of system parameters such as the turbine inlet pressure or source temperature on the characteristics of the system such as the ratio of mass flow rates, net work production as well as the efficiencies of the first and second laws of thermodynamics for various working fluids. This study finds that higher turbine inlet pressure leads to lower second law efficiency of ORC system but higher that of the combined system. Results also show that the optimum working fluid varies with the source temperature.

Abstract: In this paper, heat transfer and fluid flow monitoring experiments for pressure drop and efficiency were performed to investigate the fluid flow characteristics of rifled tubes in comparison with a smooth tube. The rifled tube has an outer diameter of 25mm, maximum inner diameter of 18.8 mm; minimum inner diameter of 17.50mm, rib height of 0.6835, rib width of 9.25, helix angles 60 o and the number of starts is four. The smooth tube has an outer diameter of 26.7mm and an inner diameter of 18.88 mm, with a wall thickness of 3.91mm. The experiments were conducted on a vertical orientation of the steel tubes (rifled and smooth) under varying flow rate of 15, 30, 40, 50, 60 and 70. The fluid used is 131.64 litres of water and the initial temperature is 25oC. The fluid is raised to an average temperature of 33oC during the experimental study. During the experiment, it was found that at 360 mins for the smooth tube, an increase in flow rate does not affect the time for the fluid (water) to attain a temperature of 33oC. For the rifled tube, as the flow rate increases, the time for the fluid (water) to attain a temperature of 33oC also increases. This is as a result of the effect of ribbing the tube. The time taken to attain the optimum temperature of 33oC is shorter using the rifled tube than the smooth tube. The rifled tube has heat transfer efficiency higher than the smooth tube. The pressure drop and the energy consumed by using the rifled tube were also found to be less than that of the smooth tube. The pressure drop increase factor was found to be 0.85 in the spirally rifled tube as compared to the smooth tube at the different flow rates. The enhancement effect of ribbing the tube is apparent.

Abstract: The combined heat and power generation system using Organic Rankine Cycle (ORC) has become a promising technology for efficient conversion of low-grade heat source to useful form of energy. In this study thermodynamic performance is investigated for a cogeneration system which consists of ORC power plant and an additional process heater as a parallel circuit. Nine different kinds of fluids of R143a, R22, R134a, R152a, R123, R113, isobutene, butane, and isopentane are considered as a working fluid of ORC. The effects of system parameters such as turbine inlet pressure, source temperature, and process heat load on the system performance including ratio of mass flow rates, net work production, and the first and second law efficiencies of thermodynamics for each fluid. Results show that there exists an optimal turbine inlet pressure to yield maximum net work. The selection of the working fluid for the combined system which assumes the maximum second-law efficiency is dependent on the source temperature level.

Abstract: Since the gas turbine systems require active cooling to maintain high operating temperature while avoiding a reduction in the system operating life, turbine blade cooling is very important and essential but it may cause the performance losses in gas turbine. This paper deals with the comparative thermodynamic analysis of gas turbine system with and without regeneration by using the recently developed blade-cooling model when the turbine blades are cooled by the method of film cooling. Special attention is paid to investigating the effects of system parameters such as pressure ratio and turbine inlet temperature on the thermodynamic performance of the systems. In both systems the thermal efficiency increases with turbine inlet temperature, but its effect is less sensitive in simpler system