In this paper, the effect of thermomechanical loading on the behavior of deflection-based harvested energies from a shape memory polymer system is experimentally investigated. Samples are created with honeycomb cells from poly-lactic acid using additive manufacturing techniques. The shape memory effect in shape recovery and force recovery paths are studied under thermomechanical tests in bending and tensile modes. The maximum recoverable strain energy is computed as well. According to the conducted thermomechanical tests, it is shown that the thermal expansion coefficient is much more dominant in the tensile mode. Some procedures are proposed to reduce the thermal expansion effect on the force recovery and arrive at higher energy harvested from a shape memory system.
Existing fossil fuels do not meet the needs of modern societies and are almost coming to an end. Hence, governments can respond both to the needs of the people and the industry, by investing in the use of renewable energies. As well as saving fossil fuels, natural gas and even water. According to the research, renewable energy, especially wind energy, has been used in recent years and are able to satisfy some of the existing needs. The purpose of present study is to investigate the techno-econo-enviro use of domestic-scale wind turbines in Iran in order to select the optimal turbine according to the geographic location of each station in the country. At the present study, five types of wind turbines, including Generic 1kW, Generic 3kW, Generic 10kW, BWC XL 1.25kW and WES Tulipo 2.5kW have been used at all stations in the country to provide the most suitable type of turbine with the help of HOMER software and based on the geographic location of each station. The results showed that among all stations and types of wind turbines, the highest and lowest total net present cost (NPC) with 49131 $ and 11622 $ respectively are related to Zanjan and Alvand stations and Generic 1kW wind turbines. Also, the cost per kWh of produced wind electricity is 2.847 $ and 0.674 $ respectively at these stations. Also in the case of using hybrid wind-diesel system by Generic 1kW, Generic 3kW, BWC XL. 1.25kW, WES 2.5kW and Generic 10kW wind turbines at the all under study stations, annually generate a total of 246409, 213951, 212826, 122460 and 152030 Kg CO2 respectievely. Another point is that at Alvand, Arak, Babolsar, Iranshahr, Kashan, Khoy and Orumieh Generic 1kW wind turbine, at Anzali, Hamedan, Ramsar and Torbate Heydarie BWC XL. 1.25kW wind turbine, and at the 91 remaining stations WES 2.5kW wind turbine are the most economically feasible options.
The use of a minimum quantity of lubrication (MQL) with extremely low consumption of lubricant in machining processes has been reported as a technologically and environmentally feasible alternative to conventional flood cooling. In hot machining, the external heat source is applied during machining that will assist to increase machining performance. Many external heating techniques are available and each type has advantages/disadvantages. 17-4 PH stainless steel (AISI630) is martensitic stainless steel, which is widely used in energy equipment, aerospace and petrochemical industries. The objective of the present paper is to integrate MQL technique, for the first time, with a hot turning process for finding an optimum possible hybrid technique for a particular machining process. The effects of different machining parameters on MQL turning of 17-4 PH stainless steel have been investigated in comparison with dry and wet machining processes. Experiments were also designed for machining using MQL and dry techniques to evaluate surface roughness, tool wear, machined surface morphology, chip morphology as well as chip formation mechanism under different pre-heating temperatures. The results show that applying MQL technique with online thermally enhanced turning (MQL-hot turning) increases the efficiency of machining of 17-4 PH stainless steel. The cutting parameters and pre-heating temperature are important parameters and should be selected carefully when using hybrid MQL-hot turning. In addition, machining with MQL is beneficial to the environment and machine tool operator health as lubricant consumption during operation with MQL is 7-fold lower than in the conventional system.
An experimental study has been carried out to characterize bubble formation, growth, and detachment mechanisms in a stagnant liquid column. Both bubble frequency and bubble detachment size were measured in different gas flow rates, injector diameters and orientations, submergence height, and liquid properties. Experiments were performed for air injection flow rate ranges between 200 mlph and 1200 mlph using needle diameters of 1.6, 1.19, 1.07, and 0.84 mm submerged in liquids with viscosities of 0.001, 0.1, 0.35, and 1 Pa.s. The data for bubble formation was obtained using a high-speed imaging technique. The results show that the bubble diameter at the departure increases as the needle diameter, liquid viscosity, and gas flow rate increase. In addition, the decrease in the submergence height results in a larger bubble at the departure. In order to analyze the changes in bubble detachment characteristics, a force modelling on a growing bubble was proposed. The experimental data were utilized for training a feed-forward back propagation neural network system to estimate the bubble detachment diameter. They were also used to propose a correlation to predict bubble diameter at the departure. The proposed correlation is found to be in the range of ± 8% of the obtained experimental data.
Clean energy harvesting and usage has gained considerable attention in the last few decades. While the horizontal axis wind turbines have been used extensively, they have certain defects and functional limitations. In the present paper, a novel oscillatory wind turbine is proposed. The conceptual design of the new turbine together with its configuration is explained. Dynamical equations of the turbine are derived and numerical analysis of these equations is performed using a developed computer code. The simulated behavior of the oscillatory turbine agrees well with the general behavior of the wind turbines, and the values for the power coefficient are acceptable for a micro-sized wind turbine.
This paper investigates the effect of inserting a ring type barrier on leakage flow of brush seals with different bristles clearances (the distance between bristle pack tip and rotor surface). The ring is placed on both upstream and downstream sides of the bristles. An axisymmetric CFD model is employed to calculate radial pressure distribution along backing plate, axial pressure variation on rotor surface, and leakage mass flow rate of the brush seal. Reynolds-Averaged-Navier-Stokes (RANS) together with non-Darcian porous medium approach is performed to solve the flow field. The accuracy and reliability of the model are evaluated through comparison of the numerical results and experimental data. The results show that inserting the ring is not effective for the brush seal with zero clearance, neither at upstream nor at downstream. In other cases, the downstream ring is considerably more effective than the upstream one, when the ring is tangent to the back of bristles. The greater the distance between the bristles and the ring, the less reduction in leakage flow. Also, the best performance is obtained for the ring height equal to clearance size. Moreover, the effect of rotor rotation on leakage flow is investigated. The results show a negligible decrease in brush seal leakage flow with increasing the rotational speed.