FLUID MECHANICS | Gas Laws

The Ideal Gas Law relates pressure, volume, molecular quantity, and temperature of an ideal gas
together in one neat mathematical expression:
PV = nRT
Where,
P = Absolute pressure (atmospheres)
V = Volume (liters)
n = Gas quantity (moles)
R = Universal gas constant (0.0821 L · atm / mol · K)
T = Absolute temperature (K)
An alternative form of the Ideal Gas Law uses the number of actual gas molecules (N) instead
of the number of moles of molecules (n):
PV = NkT
Where,
P = Absolute pressure (atmospheres)
V = Volume (liters)
N = Gas quantity (moles)
k = Boltzmann’s constant (1.38 × 10−23 J / K)
T = Absolute temperature (K)
Although no gas in real life is ideal, the Ideal Gas Law is a close approximation for conditions of
modest gas density, and no phase changes (gas turning into liquid or visa-versa).
Since the molecular quantity of an enclosed gas is constant, and the universal gas constant must
be constant, the Ideal Gas Law may be written as a proportionality instead of an equation:
PV ∝ T
Several “gas laws” are derived from this Ideal Gas Law. They are as follows:
PV = Constant Boyle’s Law (assuming constant temperature T)
V ∝ T Charles’s Law (assuming constant pressure P)
P ∝ T Gay-Lussac’s Law (assuming constant volume V )
You will see these laws referenced in explanations where the specified quantity is constant (or
very nearly constant).

For non-ideal conditions, the “Real” Gas Law formula incorporates a corrected term for the
compressibility of the gas:
PV = ZnRT
Where,
P = Absolute pressure (atmospheres)
V = Volume (liters)
Z = Gas compressibility factor (unitless)
n = Gas quantity (moles)
R = Universal gas constant (0.0821 L · atm / mol · K)
T = Absolute temperature (K)
The compressibility factor for an ideal gas is unity (Z = 1), making the Ideal Gas Law a limiting
case of the Real Gas Law. Real gases have compressibility factors less than unity (< 1). What this
means is real gases tend to compress more than the Ideal Gas Law would predict (i.e. occupies less
volume for a given amount of pressure than predicted, and/or exerts less pressure for a given volume
than predicted).

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The Thermodynamic Laws

The laws of thermodynamics explain the effects of heat in an engine. The first law states that energy can be changed but it cannot be destroyed. In a gas turbine engine, heat energy is changed to mechanical energy. The second law of thermodynamics states that heat cannot be transferred from a cooler body to a hotter body. In a gas turbine engine, heat is transferred from the hotter engine to the cooler lube oil.

Newton's first law explains why a force is needed to make the gas turbine work. In the figure, a ball on a level table will not move until it is made to move by some force such as the wind or pushing it by hand. Similarly, until the fuel and air mixture is burned in the gas turbine, there is no force for the turbine to use to turn the rotor shaft.

Newton's Second Law explains why the air must be compressed and accelerated to create a force. In the figure, a hammer is used to drive a nail. The force of hitting the nail is proportional to the mass (weight) of the hammer multiplied by the velocity of the hammer when it hits the nail. If you also use a heavier hammer, it is even easier to drive the nail into the wood. Mass and acceleration directly affect the amount of force created. The more compressed air (mass) that enters the gas turbine, the more force created from the combustion process.

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Osmosis Power Generation

 The need for energy sources, especially electrical energy, encouraging the emergence of many variations of the source of power. Moreover the pressure to create environmentally friendly power source, be one motivating factor to find energy sources other than fossil fuels. One that is currently busy with the concept of renewable energy plants that are already developed in many countries - developed countries. One part of the renewable energy power plants use osmosis energy techniques will be discussed in this article.
In principle, the power generation process involves a change of kinetic energy into electrical energy (turning on the generator rotor). The kinetic energy is commonly the case. This is due to the generation of the conventional methods (such as fossil fuel) fuel will be burned to heat water, which in turn will generate the pressure to rotate the rotor. It is then seen and tried to be utilized in the process of osmosis.
Based on the understanding, Osmosis is one of the properties owned by the liquid (fluid) to move through the fluid layer between 2 semiperrmiabel that have different density. Semipermeable layer serves to separate the two layers and can only be penetrated by water, while other particles are retained. So that the direction of movement of fluid from the fluid with a low density to higher density of the fluid to achieve the same density.
This will result in the displacement of fluid volume changes that also result in pressure on the fluid side is more concentrated. This pressure would then cause the movement of fluid and pressure that can be used as a source of kinetic energy. The concept is then used in power plants with the concept of osmosis technique with the use of seawater. By utilizing the density of sea water and pure water, generating electricity by osmosis technique can be developed.
To better understand the process of osmosis, can be seen in the image below.

On the initial conditions

During the process of osmosis has reached the point of balance
Osmosis technique is used at power plants have two distinct types, namely the PLO SHEOPP Converter and Underground Plant.
SHEOPP Converter
SHEOP Converter is a power plant installed at the bottom of the sea surface. Principles used in these plants is to use sea water as the fluid is concentrated, and utilize the flow of a river or dam which serves as a less dense fluid. Laying the basis of this plant on account of the towing also content of different heights and density of sea water itself. This factor is affecting the electrical energy that can later be resurrected.

SHEOPP Conversion Plant

PLO Underground Plant
In principle, this type of power plant Undergorund PLO has the same working prinsio SHEOPP Converter. The difference lies in the placement of plants. If the SHEOPP Converter, generator placed on the seabed to make sure the pressure and amount of fluid is right, then at power generating plant type Undergorund PLO laid under the ground. It is based to bring the pressure differential, with water from rivers or dams and sea water to the lower pressure level. For more details, can be seen in the figure below:

PLO Underground Plant
However, like many other renewable energy generation, the concept of osmosis plant with a technique still got a lot of challenges. This corresponds to a factor - a factor of quality, quantity, and economically unfavorable. The problems mainly focused on the ability of semipermeable layer as an important part of this technique, and also the cost factor needed to produce electrical energy per Watt-nya.Oleh because it's still a little power plant that was developed with this technique.
Development of plants with this technique until now, there are only a few places, such as the company Starkraft in Tofte, Norway and Eddy Potash Mine in New Mexico. Even when it was first built, the power plant in Norway is only able to produce several kilo-Watt that if converted to heat water for only 1-2 kettle.
Attention on this plant was finally draw some parties to examine and explore further. One is concern for increased work on the side semipermiabelnya layer. However, as time went on, not something that is not possible if the future generation with this technique can be one part of the basic system of power plants with renewable energy.

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Power Systems

On Power Systems are the use of an electronic component which is generally used in a series of electric motors settings. Electronic components used in electrical power systems, in principle, be capable of producing large power or be able to withstand large power dissipation.

Includes switching power electronics, control and modifier (conversion) large blocks of electric power by means of semiconductor devices. Thus the power electronics broadly divided into 2 (two) parts:
A. Power circuit2. The control circuit
In the following figure shows the relationship between the two sets above are integrated into one, where they are making use of semiconductor devices.

Power circuit components consist of diodes, thyristors and power transistors. While the control circuit consisting of diodes, transistors and integrated circuits (Integrated Circuit / IC).
By using similar equipment reliability and compatibility of the equipment (system) will be repaired. Power electronics is an important part of industries, namely in the power control systems, processes and other electronics.
I. DIODE
Diode is a union of P and N layers as images and symbols layer structure.


Terms of diodes in the ON state is positive Vak Vak while OFF is negative.


These characteristics describe the relationship between current diode (IR and IF) to Vak in the current conditions hold (OFF) or in a state of flow (ON). In the OFF state, Vak = Vr = negative, the diode current holding but there is a small leakage current Ir.
In the ON state, Vak = Vf = positive, but there is a current of the diode voltage drop across the diode Vf = Δ, and if Δ Vf is the greater for the higher diode currents, meaning * If the conduction loss Δ Vf up. Seen also on the characteristics of the diode above that when Vr is too high diode will be damaged.
Switching characteristics
These characteristics describe the nature of the work shift diodes in the ON state to OFF and vice versa.


Diode current will soon pass if Vr has reached more than the minimum diode Vf conducive and OFF at a delay of having to re-diode reverse voltage blocking capability. From the picture above tgerlihat of instantaneous reverse flow in the diode, where the reverse flow occurs at the transition state of the diode from ON state to the reverse voltage blocking conditions.
Given the nature of the reverse flow, the obtained two types of classification of the diode is:A. Fast diodes, ie diodes with Traffic immediately capable of blockingrapid reverse voltage, the order of 200 ns starting from the diode forward currentequal to 0 (zero).
2. Slow diodes, ie for the same diode requires a longer time,Q32> Qs1.
Terminology diode characteristics
Trr Reverse Recovery Time, the time it takes to be blocking diode forward voltage.Tjr: The time required by a PN junction to be blocked.TBR: The time required to form a border zone blocking Junction.Qs: The amount of charge that flows in the reverse direction during the movement of the diode ON to OFF status.
Diode type is used on a much slower converters with commutation slow / natural, such as the rectifier circuit. While Fast Diode type static converter used in the commutation itself, such as the DC Chopper, the converter commutation own dll.
The voltage capability
Reverse voltage blocking diode is, was able to withstand voltage depends on the characteristics of the voltage itself.


VRWM = normal peak working voltage.VRRM = peak overvoltage that occurs periodically.VRSM = Peak voltage is not periodic.
Diode current capability
The existence of Δ conduction voltage drop Vf diode causes power loss at the exit in the form of heat. The maximum junction temperature lies between 110 ° C - 125 ° C. Heat in excess of this temperature will cause diode damage. This maximum temperature can be achieved by a variety of load currents of the diodes.


If (AV): The current average of the maximum allowable each average current price would result in a price of final temperature on the junction diode. If the limit (AV) is also dependent on ambient temperature and type of cooling system (heat-sink).
If (RMS): maximum diode current effective price. Average price is below If (ΔV) maximum, not to guarantee the security operation, especially diode load current diode with a high form factor. (Rate Mean Square)
If (RM): peak flow over periodic price allowed.
If (BC): The price of non periodic peak flows over the allowable
Q: Boundary integral diode current loading which is still able to experience it.
This scale applies to ½ cycles or 1 ms and a guide in the selection of surge protector.
Examples of data Fast Diode Type MF 70Maximum repetitive peak reverse voltage, Vdrm = 1200 Volt.Mean forward current, If (AV) = 70 ARMS forward current, IRMS max = 110 ANon repetitive forward current, If (ms) = 700 AForward V-Drop, VFM = V, the IFM = 210 APeak reverse current, IRM = 5 mAReverse recovery time, trr = 200 nsStored, charger, Qrr = T μc (Qs)Thermal resistance, Rth-jc = 0.37 ° C / w
At follow-up article will discuss: SCR (Silicon Controlled Rectifier), TRIAC (triode Alternating Current Switch), DIAC (Bilateral Trigger Diodes) and UJT (Uni-Transistor Juntion).
May be useful,

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