Second Law Of Efficiency In Thermodynamics

A common measure of energy use efficiency is the first law efficiency , n1 . The first law efficiency is defined as the ratio of the output energy of the device to the input energy of the device. The first law is concerned only with the quantities of energy, and disregards in forms in which energy exists. It doesn't also discriminate between the energies available at different temperatures. It is the second law of thermodynamics which provides a means of assigning a quality index to energy. The concept of available energy or energy provides a useful measure of energy quality.

With this concept it is possible to analyze means of minimizing the consumption of energy to perform a given process, thereby ensuring the most efficient possible conversion of energy for the required task.

The Second law of efficiency n2 , of a process is defined as the ratio of the minimum available energy (or energy) which must be consumed to do a task divided by the actual amount of energy consumed in performing the same Task.

n2 = Min energy intake to perform the given task / actual energy intake to perform the same task.

n2 = Amin / A.

where A is the availability or energy.

A power plant converts a fraction of energy A or W max to useful work W. For the desired output of W,

Amin = W and A = W max.

Here,

I = Wmax - W and n2 = W / Wmax

Now,

n1 = W / Q1 = ( W / W max ) * ( Wmax / Q1)

n1 = n2 * n carnot

n2 = n1 / n carnot.

Since Wmax = Q1 ( 1- (To / T ))

n2 = W / Q(1-(To/T)) = n1 / n carnot

If work is involved, Amin = W ( desired ) and if heat is involved, Amin = Q (1- (To/T)).

If solar energy, Qr is available at a reservoir storage Temperature Tr and if Quantity of heat Qa is transferred by the solar collector at Temperature Ta, then

n1 = Qa / Qr

and n2 = energy output / energy input

n2 = Qa ( 1 - (To/Ta) ) / Qr (1 - (To/Tr))

n2 = n1 (((1-(To/Ta)) / (1- (To/Tr)))

Comments

ELECTRICAL COMPARATORS AND ITS WORKING

Electrical Comparators are used as a means of detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a roll. The objec...

SIMPLE CARBURETOR - CONSTRUCTION AND WORKING

CONSTRUCTION OF SIMPLE CARBURETOR : The main Components of Simple Carburetor are : Float Chamber, float, nozzle, venturi, throttle valve, inlet valve, and metering jet . In the float chamber, a constant level of petrol is maintained by the float and a needle valve. The float chamber is ventilated to atmosphere. This is used to maintain atmospheric pressure inside the chamber. The float which is normally a metallic hollow cylinder rises and closes the inlet valve as the fuel level in the float chamber increases to certain level. The mixing chamber contains venturi, nozzle and throttle valve. The venturi tube is fitted with the inlet manifold. This tube has a narrow opening called venturi. A nozzle is provided just below the centre of this venturi. The nozzle keeps the same level of petrol as that of the level in the float chamber. The mixing chamber has two butterfly valves. One is to allow air into the mixing chamber known as choke valve. The other is to al...

TOP POLLUTION RECORDED IN WORLD

CHERNOBYL NUCLEAR DISASTER (NUCLEAR POLLUTION) : In April 26,1986, the melt down of the Chernobyl nuclear reactor , in Russia, has leaked out the radioactive rays and radioactive materials. Effects : 1. In this Pollution nearly 2000 persons have been killed by the accident. 2. People suffered due to the illness such as, degeneration of the cells, severe bleeding, anemia, skin cancer. 3. Animals, Plants are also affected by nuclear radiation. MINAMATA EPIDEMIC (1953) : MARINE POLLUTION ( CASE STUDY ) Minamata is a small coastal village in Japan. The Chisso Chemical Company , which produces vinyl polymer plastics used organomercurial compound. The industry released its effluent into Minamata sea. The effluent containing mercury ions is converted into methyl mercury, which is highly toxic. The marine organisms like phytoplankton and zoo-planktons easily absorb the toxic methyl mercury compound. These organisms are consumed by small fishes and these are in ...

Mechinopedia For Mechanical Engineers

Search This Blog