Hydraulic turbines and it's types

Hydraulic turbines & Types

Hydraulic Turbines are also known as water turbines

Pelton Turbine:

Pelton turbine is a type of impulsive water turbine

Francis Turbine:

Francis turbine is a type of water turbine.  They are used widely.

Kaplan Turbine:

We can notice the little variation from the Francis turbine

Turgo turbine:

Pelton wheel modification is turgo turbine.

Cross flow turbine:

It is also known as Ossberger turbine or bankiMichell Turbine.

Wind turbine:

The Wind turbines are operated at the single stage but there is working without nozzle and inter-stage guide vanes.

Mercury vapour turbine:

In the mercury vapour turbine working fluid is mercury. It is used to improve the efficiency of the fossil fueled generating station. In some power plants we can see notice the combination of the conventional steam turbine and mercury vapours. The toxicity of the metal mercury was quickly outward.

Impulse turbine

Impulse Turbines

What is an impulse turbine? How do we calculate hydraulic efficiency and mechanical efficiency of an impulse turbine? The following important points may be noted for impulse turbines:

(a) The hydraulic efficiency of an impulse turbine is the ratio of the workdone on the wheel to the energy of the jet.

(b) The hydraulic efficiency of an impulse turbine is maximum when the velocity of wheel is one-half the velocity of jet of water at inlet.

(c) The maximum hydraulic efficiency of an impulse turbine is given by

(d) The mechanical efficiency of an impulse turbine is the ratio of the actual work available at the turbine to the energy imparted to the wheel.

(e) The overall efficiency of an impulse turbine is the ratio of the actual power produced by the turbine to the energy actually supplied by the turbine.

(f) The width of the bucket for a Pelton wheel is generally five times the diameter of jet.

(g) The depth of the bucket for a Pelton wheel is generally 1.2 times the diameter of jet.

(h) The number of buckets on the periphery of a Pelton wheel is given by,

where D is the pitch diameter of the wheel and d is the diameter of the jet.

(i) The ratio of D / d is called jet ratio.

(j) The maximum number of jets, generally, employed on Pelton wheel are six.

Hydro electric power plant turbine advantages

Hydro Electric Power Plant Turbine Advantages:

• To the power plant water source is regularly available without break. To generate electricity fuel is not required. It is properly termed as white coal.
• Through the turbine, the water is passed to do the work and to downstream the process. Its effectiveness remains exhaustive for cultivation of farms and reducing the dehydration problem.
• Compared to the nuclear power station and thermal power station the running cost is very less in the hydroelectric power plant installation.
• In case of thermal power plant we can see the cost of fuel along with the transportation cost of the fuel.
• In the thermal power station there is no problem with the disposal of ash. In the system there is no problem with the polluting gases, and particulates are not released into the atmosphere.
• We cannot find the green house effects in the hydroelectric power plant. But it causes the acid rains and emits Nitrogen into the atmosphere.
• In case of nuclear and thermal power plant, the steam turbine is put on turning gear for nearly two days during the starting and ending.
• The thought of the hydroelectric power plant is very simple and self-contained in the process.
• Compare with the other power plants the reliability of the system must be higher. The life time of the modern equipment’s have high life expectancy and without causing any trouble they work for 50 years.
• In case of the thermal power plant they work for 30 years.
• Due to the relaxation of picking up and throwing off loads in the hydroelectric power plant can be used as the idyllic spinning inverse in a system mixed up of nuclear and hydro power plant.
• At considerable range of loads modern hydro generator gives more efficiency.
• Main advantage is that the efficiency of system must be improved.
• Power plant receives more benefits from the flood control, irrigation, navigation, and afforestation and aqua culture.
• For operation process it does not required high skilled labor. Condition of man power is also low.

What is thermal equilibrium

What Is Thermal Equilibrium

When there are variations in temperature from point to point of an isolated system. thetemperature at every point first changes with time. This rate of change decreases and eventually stops. When no further changes are observed, the system is said to be in thermal equilibrium.

Properties of commonly used refrigerants

Properties of Commonly Used Refrigerants:

1. Carbon dioxide:

Carbon dioxide is widely as refrigerant in mechanical systems refrigerant, marine services, hospitals etc. due to its excellent safety properties. It is odourless, non-toxic, non-flammable, non-explosive and non-corrosive.

2. Sulphur dioxide:

Sulphur dioxide was widely used as refrigerant during early 20th century. However its use has been restricted now-a-days because of its many inherent disadvantages. It is highly toxic, non-flammable, non-explosive, non-corrosive and works at low pressures

3. Ammonia:

Ammonia is one of the earliest type of refrigerants which is still widely used in many applications due to its inheritance excellent thermal properties, It is toxic in nature, flammable explosive under certain conditions, it has low specific volume¸ high refrigerating effect, low piston displacement in case of reciprocating compressors make it an ideal refrigerant for cold storage’s, ice plants, packing plants, skating rinks breweries etc.

4. Freon-11:

Freon-11 (Trichloro fluoromethane) is used under low operating pressures; it is non-toxic, non-corrosive and non-flammable. Due to low operating pressure and high displacement, it is used in systems employing centrifugal compressors. It is used for air-conditioning applications.

5. Freon-12:

Freon-12 (Dichloro difluoromethane) is non-flammable, non-toxic and non-explosive. It is highly chemically stable. If it is brought in contact with open flame or heater elements, it decomposes into highly toxic constituents. It has not only excellent safe properties but also condenses at moderate pressure under normal atmospheric conditions.

6. Cryogenic refrigerants:

Cryogenic refrigerants are those refrigerants which produce minus temperature in between range -157°C to -273°C in the refrigerated space. The cryogenic refrigerants have exceptionally low boiling point at atmospheric pressure. Some of the widely used cryogenic refrigerants are Helium, Nitrogen, Oxygen, Hydrogen.

Mechanical properties

Mechanical properties:

Mechanical properties consist of tensile strength, toughness, malleability, hardness, Ductility, stiffness, brittle ness, Elasticity, plasticity etc.

Tensile strength

Tensile strength is the ability of the material to withstand the tensile loads without breaking.

Strength:

Strength is the ability of a material to attack the applied forces without fracturing.

Toughness:

Toughness is the ability of the material to withstand bending, or it is an application of shear stresses without fracture. The rubber or many plastic materials do not scatter so they are tough.

Malleability:

It is the capacity of the substance to tolerate deformation under compression without separation or the malleable materials, to allow a useful amount of plastic deformation. This is it undergoes compressive loading before fracture occurs. Such a material is required for manipulation by the process and rolling, forging and rivet heading.

Hardness:

Hardness is the ability of the material to withstand scratching or depression by another hard body; it is an indication of the wear resistance of the material.

Ductility:

Ductility is the capacity of the substances to undergo deformation, under tension without rupture as in wire drawing.

Stiffness:

Stiffness is used to measure the ability of the material, and not to deflect under an applied load.

Brittleness

Brittleness is the property of a material that demonstrates little or no plastic deformation before break when a force is applied. Also it is typically said in the opposite manner to ductility and malleability.

Elasticity:

Elasticity is the ability of a material to deform under load and return to its original shape and size when the load is removed. If it is made from elastic material it will be the same length before and after the load is applied. All materials possess elasticity to some degree and each one of it has its own elastic limits.

Plasticity

Plasticity is the property which is strictly opposite to elasticity; the ductility and malleability are actual cases of plasticity. Plasticity is the state of a material which has been fully loaded beyond its elastic limit so as to cause the material to deform permanently. Under such conditions the material takes a permanent set and will not return to its original size and shape when the load is removed.

• What is the thing(s) that only Mechanical Engineers know?

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• We know that AC isn't just about making coldness, it can be used to make a room hot too because it is a Air conditioning. You can also use an AC as an improvised heater by turning it backwards, so it blows colder air out and hot air in but that would be far from efficient. Also, it adjusts the air velocity and the humidity.
• We know the reason behind the air conditioning system in ICU room is not just for luxury hospital but to cool the machinery also. Overheating the machinery can cause malfunctions.
• We know the reason behind why airplane windows always have round edges instead of square because sharp corner of square window is weakened by stress concentration.

• We know “why are tyres in black color ?” because of chemical compound carbon black is added in rubber which increases the strength and durability of tyres and carbon maintains the quality of tyres by protecting them from UV lights and ozone.

• We know “why are there stones alongside railway tracks ?” - The crushed stones are what are known as ballast. Their purpose is to hold the wooden cross ties in place, which in turn hold the rail in place. It is used to bear load from the rail road ties, to facilitate drainage of water & also to keep down vegetation that might interfere with the track.

• We know “why do some tuned car have very inclined tires ?” - The tilt of the wheel is know as camber angle. Tilting the wheel in that manner ( as shown in pic) is called negative camber. Mounting the wheel with a negative camber improves grip under hard cornering as it counteracts rolling.

• We also know “what does the green zone in speedometer indicate ?” - It is the zone where you will have more efficient speed where the fuel consumption is low.

• We know “why are roller bearings present in the bridge ?” - They are there to release any strain induced due to shrinkage and expansion of the bridge girder.( due to temperature, creep and shrinkage of concrete )

• We know that “It's more efficient to drive with Air conditioning on than window open above the speeds of about 55–60 kmph” because opening the window increase the air drag, and slows the car down so it needs more fuel to run.