Diesel cycle otto cycle the only difference is in process 23. Comparison of otto, diesel and dual cycles notes edurev. Improved and modern form of old diesel engines cycles. Why is diesel cycle more thermally efficient than otto. I want to compare the ideal diesel, otto and dual cycles with constant specific heats. Dual cycle, or limited pressure cycle, is a thermodynamic cycle that combines the otto cycle and the diesel cycle. Fuel is sprayed into the cylinder at high pressure when the compression is complete, and there is ignition without a spark. The main difference between otto cycle and diesel cycle is that in otto cycle heat addition takes place at constant volume and in diesel cycle heat addition takes places at constant pressure. In the dual cycle, combustion occurs partly at constant volume and partly at constant pressure. Difference between spark ignition and compression ignition. Part 1, comparison between otto, diesel and dual cycle comparison of otto, diesel and dual cycle difference between otto, diesel and dual cycle difference of otto, diesel and dual cycle. Dual combustion cycle is a combination of otto cycle and diesel cycle. This lesson is important for all mechanical engineering competition exams and also gate, ies, ias, psu, ssc je, lmrc, dmrc, rrb, railway, rpsc aen, bpsc etc. This cycle is very similar to the diesel cycle, except that the otto cycle forms the basis of a sparkignition s.
Diesel cycle is a gas power cycle invented by rudolph diesel in the year 1897. For this reason, the pressure is kept moreorless constant because fuel is being added as the volume is increasing. So, the otto cycle is more suitable for the reciprocating type of field. It is sometimes called semi diesel cycle, because semi diesel engines work on this cycle. In otto cycle as well as in diesel cycle heat rejection takes place at constant volume. Dual combustion cycle also known as the limited pressure or mixed cycle, seiliger cycle or sabathe cycle.
The british engineer james atkinson 18461914 realized that the efficiency of the otto cycle could be improved if the combustion gases could be expanded to near atmospheric pressure before being exhausted from the engine. Area under 5 2 3 6 the heat rejected is different in each case and can be established from the ts diagram as follows. Diesel is used as fuel in this cycle as it can be compressed at higher compression ratio. What is the difference between spark ignition and compression ignition.
It can be used to describe internal combustion engines. As seen in the figure, the ideal diesel cycle consists of four thermal lines that represent. Setting some parameters to be defined 1 will reduce to either the otto or diesel cycle. It has high thermal efficiency and compression ratio 11. These processes can be easily understood if we understand pv pressurevolume and ts temperatureentropy. Calculate the air standard efficiency and mean effective pressure for the cycle. In otto cycle engines, the pressure in the cylinder at the end of the expansion power stroke is still 3 to 5 atm when the exhaust valve opens. The only difference between ideal otto cycle and ideal diesel cycle is the heat addition process. Diesel engines are used in aircraft, automobiles, power generation, diesel electric locomotives and both surface ships and submarines. The otto cycle is more commonly used in modest size engines single cylinders for lawn mowers, etc. The internal combustion engines piston makes a full cycle in the cylinder during the intake and exhaust cycles and thus generates wear, frictional losses, and consumes additional power the engine could supply to the crankshaft in moving internal mass back and forth in the cylinder.
In the diesel cycle, fuel begins to enter near the end of the compression stroke, and continues past top dead center, into the expansion stroke. This is in contrast to igniting the fuelair mixture with a spark plug as in the otto cycle fourstrokepetrol engine. An internal combustion engine is exposed to the highest temperature after combustion of fuel only for a short duration, and it gets time to become cool in the other processes of the thermodynamic cycle. Power cycles otto cycle spark ignition diesel cycle. Difference between otto cycle and diesel cycle with pdf. In it, fuel is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is then injected. It is also known as constant pressure cycle because heat is added in it at constant pressure. The otto cycle was developed by german engineer nikolaus otto in 1876. In the 1890s, a german inventor, rudolf diesel has patented his invention of an efficient, slow burning, compression ignition, internal combustion engine.
An idealized diesel engine cycle is shown in figure 3. Comparison between otto, diesel and dual cycles for gate. I am unable to determine the common inputs to all three which can give me the efficiency for all the cycles. An otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. Practically, otto cycle is less efficient because of the problem of knocking. It is the thermodynamic cycle most commonly found in automobile engines. Thermal cycle that is a combination of the otto cycle and the diesel cycle. How does the ideal diesel cycle differ from the ideal otto c. It is widely used in diesel engines diesel cycle is similar to otto cycle except in the fact that it has one constant pressure process instead of a constant volume process in otto cycle diesel cycle can be understood well if you refer its pv and ts diagrams. Mallikarjuna indian institute of technology madras 4.
The original cycle proposed by rudolf diesel was a constant temperature cycle. For the same compression ratio the efficiency of otto cycle is more than the diesel cycle. In this article we will take a collective look at these three cycles in order to compare and contrast them, so that we can come to know the relative advantages and disadvantages of these cycles. The otto cycle is a description of what happens to a mass of gas as it is subjected to changes of pressure, temperature, volume, addition of heat, and removal of heat. Otto cycle engine an overview sciencedirect topics. Another difference between both cycles lies in the values of the compression ratio, which varies from 12 to 22 for the diesel engine, while it oscillates only between 6 and 10 for the otto engine or gasoline engines.
This is the major difference between otto cycle and diesel cycle. Comparison of diesel cycle and otto in fourstroke motor. If the compression ratio of an otto cycle and a diesel. In later years diesel realized his original cycle would not work and he adopted the constant pressure cycle, which is known as the. What is the relation between an otto cycle, diesel cycle. In this lesson we study about the comparison between otto cycle, diesel cycle and dual cycle efficiencies in different cases. The important variable factors which are used as the basis for comparison of the cycles are compression ratio, peak pressure, heat addition, heat rejection and the net work. The main and basic difference between otto cycle and diesel cycle is that of the way the way they supply heat to the engine to initiate combustion. On the other hand, gas turbine plant, a steady flow device, is. Spark ignition uses petrol as the fuel, but compression ignition uses diesel. I am interested in knowing the relationship between r compression and nth efficiency.
Today, we are going to learn about the differences between these two cycles i. We can make all sorts of arguments about thermal efficiency, and related engineering concepts, but the interesting thing is this. Comparison of brayton cycle with otto cycle me mechanical. At the end of the articles, you will find the pdf which you can easily download. First, i will start by explaining the way an otto cycle works. There are many other differences which are described below. Our vehicles engines operate on either one of these cycles and the main difference between both is the way each one supplies heat to the engine to initiate combustion.
Comparison between otto, diesel and dual cycle 1 4 v s 1 4 for the same compression ratio and same heat input 1234 otto cycle, 1234 diesel cycle and 12234 dual cycle. In this cycle, heat is absorbed partly at a constant volume and partly at a constant pressure. During the working stroke in otto cycle pressure of the gas rises at constant volume, in diesel cycle volume rises at constant pressure, and in duel cycle engine some portion of working stroke is at constant volume and rest is at constant pressure. Diesel cycle vs otto cycle otto and diesel cycles are present in our everyday lives. Today we will be studying the differences between otto and diesel cycle is very detail. Interactive comparison which shows the relationship between the various systems of an internal combustion engine with fuel injection ignition which develops the diesel cycle and the relationship between systems of an internal combustion engine with spark ignition that develops the otto cycle and plots synchronously in two diagrams pressure x volume approximations of the idealized theoretical. O tto cycle is a gas power cycle that is used in sparkignition internal combustion engines modern petrol engines. The main difference between otto and diesel cycle is that the otto cycle has low thermal efficiency and the diesel cycle has high thermal efficiency. Gas movement takes place through holes called ports in the cylinder. The efficiency of otto cycle is less as compared with the diesel cycle. Consider process 23 this is the step where heat is transferred into the system we model it as constant pressure instead of constant volume. Diesel engine cycle comparison otto cycle vs other. Two stroke cycle engine petrol engine in two stroke cycle engines, the whole sequence of events i.