Posted tagged ‘mechanical energy’

Electrical Power Generation System Using Railway Track

September 29, 2011

The system includes a power source, such as a power generation device or an external powersource. The power co-generation system includes first and second electrical capacitance portions that are electrically coupled to the power source and that are configured to carry positive and negative charges, respectively. The power co-generation system further includes a biasing device that is configured to separate the first and second capacitance portions with respect to one another. Thus, by varying the distance between the capacitance portions in response to a vehicle on the rail, the capacitance portions cooperate to act as a variable capacitor that facilitates the co-generation of power with respect to the system. That is to say, the mechanical energy of the biasing device is converted into electrical energy for the system.


In accordance with another exemplary aspect of the present technique, a method of co-generating power via a vehicle traveling on a rail is provided. The method includes the act of driving first and second capacitor plates with respect to oneanother in response to the vehicle that is traveling on the rail. The method also includes the act of charging the first and second capacitor plates via a power source, such as a power generation device or an external power source. The method  further includes biasing the first and second plates apart from one another, thereby displacing the plates with respect to one another. This displacement changes the electrical capacitance between the first and second plates and, resultantly, increases the electric potential between the first and second plates. In turn, this displacement of the first and second plates facilitates the co-generation of electrical energy from the kinetic and potential energy of the vehicle on the rail.


Fluid Machines – Pumps and Turbines

September 18, 2011


What is a fluid Machine ?
A fluid machine is a device which converts the energy stored by a fluid in to mechanical energy or work.


What are positive displacement machines ?
The machine functioning depend essentially on the change of volume of a certain amount of fluid within the machine. There is a physical displacement of the boundary of certain fluid hence it is called positive displacement machine. 

Based on the direction of fluid flow how are the fluid machines classified ?
According to the flow direction of fluid, the fluid machines are classified as
Axial flow machines – The main flow direction is parallel to the axis of the machine.
Radial flow machines – The main flow direction is perpendicular to the axis of the machine ie. in radial direction
Mixed flow machines – The fluid enters radially and leaves axially or vice-versa. 

What is a turbine ?
A turbine converts the energy of the fluid in to mechanical energy which is then utilized in running a generator of a power plant. 

State the difference between impulse and reaction turbines ?
At the inlet of the turbine the energy available is only kinetic energy, the turbine is known as impulse turbine. If the inlet of the turbine, possesses kinetic energy and pressure energy, the turbine known as reaction turbine. 

What are Homologous units ?
In utilizing scale models in designing turbo machines, geometric simililitude is necessary as well as geometrically similar velocity diagrams at entrance and exit from impellers. Two geometrically similar units having similar vector diagrams are called homologous units. 

Define specific speed based on power.
The specific speed (Ns ) of turbine is defined as the speed of some unit of series of such size that it produces unit power with unit head. . 

Define specific speed based on discharge.
The specific speed ( Ns ) of the pump is defined as the speed of some unit of the series of such size that it delivers unit discharge at unit speed 

What is the significance of specific speed ?
The specific speed inversely proportional to the head across the machine. So low specific speed corresponds to high head across it and vice-versa.
The specific speed is directly proportional to the discharge through the machine or power produced by the machine. So low specific speed therefore refers to low discharge or low power machine and vice-versa. 

Name the main parts of a radial flow reaction turbine ?
i) Casing ii) Guide vane iii) Runner iv) Draft tube. 

What is the purpose of the guide vanes in radial flow reaction turbine ?
The purpose of the guide vane is to convert a part of pressure energy of the fluid at its entrance to the kinetic energy and then direct the fluid on to the number of blades. 

What is a draft tube ? In which turbine it is mostly used.
The draft tube is a conduit which connects the runner exit to the trail race, when water is being finally discharged from the turbine. In reaction turbine , the draft tube is mostly used. 

What is the primary function of a draft tube ?
The primary function of the draft tube is to reduce the velocity of the discharged water to minimize the loss of kinetic energy at the outlet. 

Name the main parts of Kaplan turbine.
i). Scroll casing ii). Guide vanes iii). Hub with vanes iv). draft tube 

Name the main parts of pelton wheel .
i) Nozzle ii) Runner with buckets iii) Casing. 

An inward flow reaction turbine running at 250rpm has D1 = 1m, b1 = 0.2m, D2 = 0.5m and b3 = 0.3m. If the water enters the wheel radially at 3.5m/s velocity, determine the discharge and velocity of the flow at the outlet. Assume vane thickness at the extremities to be negligible.
Q = p D1 b1 Uf1 = p D2 b2 Uf2 = p x 1 x 0.2 x 3.5 = 2.199 m3/s
Uf2 = 2.99/ (p x 0.5 x 0.3) = 4.666 m/s 

What are the different performance characteristic curves ?
i) Variable speed curves (or) main characteristics
ii) Constant seed curves (or) operating characteristics
iii) Constant efficiency curves (or) Muschel characteristics 

Give an example for a low head turbine , a medium head turbine and a high head turbine.
Low head turbine – Kaplan turbine
Medium head turbine – Francis turbine
High head turbine – Pelton wheel. 

what are the purposes of casing of a centrifugal pump
i) To provide water to and from the impeller
ii) To partially convert the kinetic energy in to pressure energy 

What are the different types of casing in centrifugal pump ?
i) Volute casing ii) Turbine casing (or) casing with guide blades 

What is a positive displacement pump ?
In the case of positive displacement pumps, the fluid is physically pushed from an enclosed space. The positive displacement pumps can be either reciprocating type or rotary type. 

Where is the reciprocating pump well suited ?>
The reciprocating pump is well suited for relatively small capacities and high heads. 

what are the main components of a reciprocating pump ?
1)cylinder 2) Piston 3) suction valve 4) Delivery valve 5) Suction pipe 6) delivery pipe 7) crank shaft and connecting rod mechanism. 

Define coefficient of discharge of reciprocating pump.
The ratio between the actual discharge and theoretical discharge is known as coefficient of discharge. Cd = Qact / Qthe. 

Define slip of the reciprocating pump. When does the negative slip occurs ?
The difference between theoretical discharge and actual discharge is called the slip of the pump.
Slip = Qthe. – Qact , % of slip = (Qthe. – Qact ) x 100 / Qthe.
Negative slip occurs when delivery pipe is short suction pipe is long and pump is running at high speed. 

Differentiate between single acting and double acting reciprocating reciprocating pump.
In single acting pump, there is one suction valve and one delivery valve. On the backward stroke of the piston, the suction valve opens and water enters into the cylinder space. On the forward stroke, the suction valve closes and delivery valve opens, the water is forced through the delivery pipe.
In the double acting pump, there are two suction valves and two delivery vales one in the front and one in the rear. When the piston moves backward, the suction valve in the front opens and delivery valve in the rear opens and water is forced through it. When the piston moves forward, the suction valve in the rear opens and delivery valve in the front opens and water is forced through it. 

What is an indicator diagram of a reciprocating pump ?
The indicator diagram of a reciprocating pump is the diagram which shows the pressure head in the cylinder corresponding to any position during the suction and delivery strokes. 

A single acting single cylinder reciprocating pump has the following characteristics.
Discharge = 6 lps, suction head = 4m, Delivery head = 20m, Find the energy required to drive the pump.
Energy required = r g Q ( Hs + Hd ) Watts = (1000 x9.81 x 6×10-3 x (4 + 20) / 1000
= 1.409 kW. 

What is an air vessel and what is its purpose ?
An air vessel is a closed chamber connected on the suction or delivery or both sides of the reciprocating pump to obtain a more uniform flow. 

Name some rotary positive displacement pumps.
a. Gear pumps.
b. Vane Pumps.
c. Piston pumps.
d. Screw pumps.


August 23, 2011

01-wind up battery-crank up battery-battery storage technology-hand powered spinning re-charger battery

The Wind up battery is the endless independent source of power. It is the only tool you will need to charge your mobile phone batteries, notebook batteries, GPS or any other modern gadget which is in this information-packed world essential life companion. The use of wind up battery charger is easy and being that it is totally portable and independent power supply, it is a valuable part of accessory of every trekker’s, backpacker’s, traveler’s adventures journey. It is also an essential back up power supply for any critical emergency events when there is no power supply available nearby.

How does it work?

01-wind up battery- operation-working-twisting clockwise or anticlockwise makes charging

The wind up battery mechanism uses internal generator, which is usually hand-powered by spinning the handle on the device. The hand motion, in which AC alternator is driven by a crank converts human mechanical energy and generates the electrical power, by spinning magnets past a coil of wire, which is stored in battery. To charge the device, utilizing the wind up mechanism the hand crank needs to be pulled out of the folded position, and spun in clockwise/counterclockwise direction. After some time of cranking, when the device is charged the handle is folded into position and the device is available to use.

There are also foot powered wind up battery devices, which generate power and self charge by human energy through step action. These are able to jump-start a boat or automobile battery, and power a wide array of instruments and accessories and present a valuable and versatile tool for power supply.

The Devices using wind up mechanism

There are several devices on market which utilize the wind up mechanism. It can be used as a wind up battery charger, wind up flashlight, wind up radio, wind up clock, mp3 player, or a larger electricity supply unit. Usually there are hand cranks folded into the devices, which can be pulled out when needed. The wind up devices are a great way to promote environmentally clean green energy source as the power is derived through windup mechanism which efficiently harvests the human energy and converts it to electricity.

If you are an environmentally conscious consumer who likes to travel and have a power charger available for his electric devices and an emergency power supply then the wind up battery is the device to look for.

01-exploded view of wind up battery-wind up mechanism