ERICSSON CYCLE (1850) AND ITS PROCESS

The Ericsson cycle is made up of two reversible isotherms and two reversible isobars.

For 1 kg Of Ideal gas

Q1-2 = W1-2 = RT1 ln (P1 / P2)

Q2-3 = Cp (T2 - T1) ; W2-3 = P2 (V3-V2) = R ( T2 - T1 )

Q3-4 = W3-4 = - RT2 ln ( P1 / P2 )

Q4-1 = Cp (T1-T4) ; W4-1 = P1(V1 - V4) = R (T1 - T2)

Since part of the heat is transferred at constant pressure and part at constant Temperature, the efficiency of the Ericsson Cycle is less than that of the Carnot cycle. But with ideal regeneration Q2-3 = Q4-1 so that all the heat is added from external source at T1 and all the heat is rejected to an external sink at T2, the efficiency of the cycle becomes equal to the Carnot cycle efficiency, since

N = 1 - (Q2 / Q1) = 1 - (T2 / T1)

The regenerative, Stirling and Ericsson cycles have the same efficiency as the Carnot cycle, but much less back work. Both cycles utilize regeneration, a process during which heat is transferred to a thermal energy storage device called a regenerator during one part of the cycle and is transferred back to the working fluid during another part of the cycle. Hot air engines working on these cycles have been successfully operated. But it is difficult to transfer heat to a gas at high rates, since the gas film has a very low thermal conductivity. So there has not been much progress in the development of hot air engines. However, since the cost of internal combustion engine fuels is getting excessive, these may find a field of use in the near future.

Comments

Advantages And Disadvantages Of Air Refrigeration System :

Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.

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...

THROTTLE GOVERNING OF STEAM TURBINES

Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the turbine constant at part load and hence this method of governing is called "Throttle Governing". Construction : Throttle governing system consists of a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber. Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movemen...

Mechinopedia For Mechanical Engineers

Search This Blog