جستجوی مقالات مرتبط با کلیدواژه « Charge » در نشریات گروه « مکانیک »

Phase change materials (PCMs) can be used in solar water heaters to store excess heat energy available during sunny hours. The purpose of this study is to investigate the performance of the solar water heater system with heat pipe, along with the energy storage system containing phase change materials (PCMs). In this study, a cylindrical galvanized tank with double spiral coil and containing PCM acts as a thermal energy storage unit. Paraffin is used as PCM and water is used as a heat transfer fluid (HTF) to transfer heat from the water heater tank to the spiral tubes and from there to the energy storage tank. The charging and discharging process tests are carried out on sunny days and in real operating conditions. The importance of temperature changes of HTF heat transfer fluid and PCM phase change material as well as the range of changes have been discussed. Functional variables of charge and discharge energy and thermal energy efficiency have been studied. The calculated charging efficiency, 75.7 %and the efficiency of the energy storage unit for the discharge process was 61.1 %. PCM saved 2700 kJ of heat in 70 minutes for 80 ° C during charging and 1650 kJ of heat in 50 minutes at 25 ° C and 42 liters per minute in storage, discharge. He made energy. From the tests, it was found that PCM improves the performance of the system by increasing the charging energy efficiency and the thermal efficiency of the hot water storage tank.

Nowadays, atomic force microscope is considered as a useful tool in the determination of intermolecular forces and surface topography with the resolution of nanometers. In this kind of microscope, micro cantilever is considered as the heart of the microscope and is used as a measuring tool. This paper is aimed towards investigating the behavior of a piezoelectric micro cantilever with a triangular head, in self-measure mode and close proximity to the surface of a sample. Output charge from the piezoelectric layer and also the output current, in this mode, is considered as an effective factor in the measurement of the bending. The micro cantilever’s vibration behavior becomes nonlinear, as it approaches the surface of the sample. Surely the piezoelectric layer in the self-measure mode can be considered as a good measuring tool, only when it reflects the effects of the nonlinear interaction between the tip of the probe and the surface of the sample in its measurements. In order to investigate this matter, first the differential equations that are ruling over the vibrating movements of the piezoelectric micro cantilever with a triangular head, are transformed into normal nonlinear differential equations using the Galerkin method. Then the resulting nonlinear differential equation is solved using the multi-scale method. After solving the differential equation ruling over the problem, the micro cantilevers behavior in the proximity of the surface of the sample is simulated and the effect of factors such as balancing distance, oscillation modes and the substance of piezoelectric layer are investigated.

Modeling and simulation are useful tools to optimize and analyze the dynamic behavior of lead-acid batteries. One of the main problems is that the governing equations of lead-acid batteries are highly coupled which significantly increases the computational time of numerical methods in simulations. Using reduced order models (ROM) is one of the best ways to overcome this difficulty. In the present study, the one-dimensional electrochemical governing equations of lead-acid battery are solved using model order reduction based on proper orthogonal decomposition (POD). To show the capability of this method, the governing equations including conservation of charge in solid and liquid phases and conservation of species are solved simultaneously for a lead-acid cell during discharge, rest and charge process. The results of reduced order model including cell voltage, acid concentration and state of charge (SoC) are compared to the results of finite-volume method (FVM). The obtained numerical results show that not only the POD-based ROM of lead-acid battery significantly decreases the computational time (speed-up factor of 15) but also there is an excellent agreement with the results of previous computational fluid dynamic (CFD) models.

Provide a comprehensive plan for the electric vehicles in a micro-grid with regard to network limitations and vehicles as well as economic goals of the utmost importance. In this paper, the Hybrid Big Bang to Big Crunch algorithm has been used to provide scheduling for electric vehicle presence in the network to reduce costs. In order to verify the proposed method, studies in a 24 hour period on a distribution system and in the presence of electric vehicles have been done with real movement patterns. Effectiveness and usefulness of the proposed technique scheduling resources in a 24 hour period on a micro-grid sample tested. The results show that the proposed method of charging / discharging EV can reduce operating costs.