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Diesel cycle

The Diesel cycle is a combustion process of a reciprocating internal combustion engine. In it, fuel is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is injected; this is in contrast to igniting the fuel-air mixture with a spark plug as in the Otto cycle engine. Diesel engines are used in aircraft, power generation, diesel-electric locomotives, both surface ships and submarines; the Diesel cycle is assumed to have constant pressure during the initial part of the combustion phase. This is an idealized mathematical model: real physical diesels do have an increase in pressure during this period, but it is less pronounced than in the Otto cycle. In contrast, the idealized Otto cycle of a gasoline engine approximates a constant volume process during that phase; the image shows a p-V diagram for the ideal Diesel cycle. The idealized Diesel cycle assumes an ideal gas and ignores combustion chemistry, exhaust- and recharge procedures and follows four distinct processes: 1→2: isentropic compression of the fluid 2→3: reversible constant pressure heating 3→4: isentropic expansion 4→1: reversible constant volume cooling The Diesel engine is a heat engine: it converts heat into work.

During the bottom isentropic processes, energy is transferred into the system in the form of work W i n, but by definition no energy is transferred into or out of the system in the form of heat. During the constant pressure process, energy enters the system as heat Q i n. During the top isentropic processes, energy is transferred out of the system in the form of W o u t, but by definition no energy is transferred into or out of the system in the form of heat. During the constant volume process, some of energy flows out of the system as heat through the right depressurizing process Q o u t; the work that leaves the system is equal to the work that enters the system plus the difference between the heat added to the system and the heat that leaves the system. Work in is done by the piston compressing the air Heat in is done by the combustion of the fuel Work out is done by the working fluid expanding and pushing a piston Heat out is done by venting the air Net work produced = Q i n - Q o u t The net work produced is represented by the area enclosed by the cycle on the P-V diagram.

The net work is produced per cycle and is called the useful work, as it can be turned to other useful types of energy and propel a vehicle or produce electrical energy. The summation of many such cycles per unit of time is called the developed power; the W o u t is called the gross work, some of, used in the next cycle of the engine to compress the next charge of air The maximum thermal efficiency of a Diesel cycle is dependent on the compression ratio and the cut-off ratio. It has the following formula under cold air standard analysis: η t h = 1 − 1 r γ − 1 where η t h is thermal efficiency α is the cut-off ratio V 3 V 2 r is the compression ratio V 1 V 2 γ is ratio of specific heats The cut-off ratio can be expressed in terms of temperature as shown below: T 2 T 1 = γ − 1 = r γ − 1 T 2 = T

Reid House (Atlanta, Georgia)

The Reid House at 1325-1327 Peachtree St. NE, in Atlanta, known as Garrison Apartments and as 1325 Apartments, was built as a luxury apartment building in 1924, it was the third luxury apartment building built in Atlanta. It received a $2 million renovation during 1974 and was converted to a luxury condominium building in 1975; the ten-story building was designed by architect Philip T. Shutze of architectural firm Hentz and Adler in Classical Revival architecture; the 1974 renovation was by architect Eugene I. Lowry, it was listed on the National Register of Historic Places in 1979. The NRHP nomination lists 24 units. Reid House, or at least some part of it, has been described as being designed by Neel Reid, it is located across Peachtree Street from the High Museum of Art. The Reid House, at an Atlanta condos website, with pictures

Central Calcutta Polytechnic

Central Calcutta Polytechnic is a government polytechnic college in the city of Kolkata, West Bengal in India. It is affiliated with the West Bengal State Council of Technical Education, approved by All India Council for Technical Education and provides diploma level technical education to its students. At the time of foundation in 1963, Central Calcutta Polytechnic was a sponsored institute with two other institutes: Institute of Hotel Management & Catering Technology, National Institute for Technical Teachers Training & Research; the government of West Bengal took over the Institute in 1974. The Polytechnic offers diploma courses in mechanical, electronics & telecommunication, computer science engineering, it conducts post-diploma course in medical electronics. These courses are recognised by AICTE and WBSCTE. Official website Central Calcutta Polytechnic On Facebook