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Kinetics of a Rigid Body
Published in M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed, Engineering Dynamics, 2022
M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed
When we get work from a machine or a body, that work is smaller than the energy needed to supply for that machine or body to do the work. It is not only true for machines, but is also true in our practical lives as well where a part of the work is utilized and the rest of the supplied energy is lost. In the case of an engine, this dissipation of energy is used as friction, to warm up the engine, etc. This dissipation of energy cannot be stopped completely, but by applying different technologies this dissipation can be reduced. In this case, equation of energy is equivalent to supplied energy = effective energy + dissipated energy. The efficiency of a machine is defined as the ratio of the output energy to the input or supplied energy. It is commonly denoted as η.η=OutputEnergyInputEnergy
Energy Storage Systems
Published in Radian Belu, Energy Storage, Grid Integration, Energy Economics, and the Environment, 2019
A flywheel energy storage system converts electrical energy supplied from DC or three-phase AC power source into kinetic energy of a spinning mass or converts kinetic energy of a spinning mass into electrical energy. Basically, a flywheel is a disk with a certain mass that can spin, holding kinetic energy. Modern high-tech flywheels are built with the disk attached to a rotor in upright position to prevent gravity influence, being charged or discharged by a reversible electric motor-generator system. When dealing with its efficiency however it gets more complicated, as stated by the physics principles, the friction during operation, being major factor, so to increase the efficiency is to minimize friction. This can be accomplished in two ways: the disk can spin in vacuum, less friction, and by spinning the rotor on electromagnetic bearings so it basically floats. The spinning speed for a modern flywheel reaches up to 16,000 rpm and offers a capacity up to 25 kWh, which can be absorbed and injected almost instantly. A complete flywheel energy storage system consists of the following components: high-speed rotor attached to a shaft supported by bearings with good lubrication or with magnetic suspension to minimize frication, an electromechanical energy converter, power electronic conditioning and control units.
D.C. Machines
Published in Christopher R Robertson, Further Electrical and Electronic Principles, 2010
As with any machine, the efficiency may be calculated from the ratio of the output power to the input power. In addition, the losses involved can be split between those that are unvarying (fixed losses) and those that will vary according to the loading placed on the machine. The condition for maximum efficiency is again achieved when the variable losses are equal to the fixed losses. The power flow diagram for a given type of machine identifies this division of losses. These diagrams can prove very useful when solving machine problems, and it is recommended that they be referred to when calculations are undertaken.
Assessment of waste plastic oil blends on performance, combustion and emission parameters in direct injection compression ignition engine
Published in International Journal of Ambient Energy, 2019
Hariram Venkatesan, Seralathan Sivamani, Kunal Bhutoria, Harsh H. Vora
Mechanical efficiency is the measure of useful work performed by the system with the input of fuel and energy. Figure 12 shows the variation in mechanical efficiency for all fuel blends at all loads. From the plot, it can be noticed that there was a constant increase in mechanical efficiency with increasing load for straight diesel and PO blends. PO30% blend showed marginally better efficiency at low and part load due to higher ignition delay resulting in enhanced premixed combustion period and poor atomisation of fuel at high loads. The mechanical efficiency of straight diesel and PO15% blend was found to be 67.72% and 69.84% at full load condition.
Study on Friction Characteristics of ADC12-POM Gear Pair
Published in Tribology Transactions, 2023
Yangshou Xiong, Quanwei Wang, Kang Huang, Zhou Zongshan
The efficiency is defined as the ratio of the output power to the input power. Mathematically, it can be expressed as the limit of work divided by time interval as approaches zero, known as instantaneous power. Hence, the relationship can be formulated as follows: where is the combined force on the mass and is the velocity of the mass.