* The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will Decrease*. The compression ratio is the ratio of the volume of the cylinder and the combustion chamber when the piston is at the bottom, and the volume of the combustion chamber when the piston is at the top The thermal efficiency of a diesel 1 point cycle having fixed compression ratio, with increase in cut-off ratio will: Be independent Increase None of the mentioned Decreas Question: نقطة واحدة The Thermal Efficiency Of A Diesel Cycle Having Fixed Compression Ratio, With Increase In Cut-off Ratio Will Decrease Increase None Of The Mentioned Be Independent Sously This In A Carnot Engine Cycle, The Working Medium Rejects Heat At A. Temperature Lower None Of The Mentioned Constant Higher O نقطة واحدة : The Efficiency. Question is ⇒ The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will, Options are ⇒ (A) increase, (B) decrease, (C) be independent, (D) may increase or decrease depending on other factors, (E) none of the above., Leave your comments or Download question paper

** The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will a) increase b) decrease c) be independent d) none of the mentioned; The pressure at the end of compression, in diesel engines, is approximately a) 10 bar b) 20 bar c) 25 bar d) 35 bar; The combustion in spark ignition engine is a**. Thermal Efficiency for Diesel Cycle A typical diesel automotive engine operates at around 30% to 35% of thermal efficiency. Low-speed diesel engines (as used in ships) can have a thermal efficiency that exceeds 50%. Thermal efficiency for Diesel cycle 23. The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will (a) increase (b) decrease (c) be independent (d) may increase or decrease depending on other factors (e) none of the above. Ans: b. 24. Pick up the wrong statement (a) 2-stroke engine can run in any directio

**Of** course the answer is (**a**) because if we recall the **efficiency**-**compression** **ratio** graph we'll see that if we decrease the cut-off **ratio** **the** eff curve will be pulled up and approach to the otto **cycle** **efficiency** at cut-off ratio= (c) thermal efficiency of Otto cycle is same as that for Diesel cycle (d) thermal efficiency of Otto cycle cannot be predicted. 6. In air standard Diesel cycle, at fixed compression ratio and fixed value of adiabatic index (γ) (a) thermal efficiency increases with increase in heat addition cut-off ratio (b) thermal efficiency decreases with. diesel cycle: volumetric compression ratio, expansion ratio, cut-off ratio and efficiency in Thermal Engineering and Power Unit We were discussing Otto cycle , an ideal cycle for internal combustion spark ignition reciprocating engines or simply petrol engines and al..

When we rewrite the expression for thermal efficiency using the compression ratio, we conclude the air-standard Otto cycle thermal efficiency is a function of compression ratio and κ = cp/cv. Thermal efficiency for Otto cycle - κ = 1. The efficiency by which they do so is measured in terms of thermal efficiency, and most gasoline combustion engines average around 20 percent thermal efficiency. Diesel is typically higher-approaching 40 percent in some cases, explains GreenCarReports.com Solved Problem 3.6 - An ideal air-standard Diesel cycle engine has a compression ratio of 18 and a cutoff ratio of 2. At the beginning of the compression process, the working fluid is at 100 kPa, 27°C (300 K) It means that otto cycle gives more work than diesel cycle for same compression ratio. so, otto cycle has higher efficiency than diesel cycle. I think it is the easiest way of understanding Diesel cycle =>1-2-3'-4' Dual cycle => 1-2-2-3-4-1 . All the cycles starts from the same initial state 1 and the air is reversible adiabatically compresed to state 2, as the compression ratio is same. For the same compression ratio and heat input, minimum heat is rejected in the Otto cycle arid the maximum heat is rejected in the Diesel cycle

The thermal efficiency of a diesel cycle having fixed compression ratio with increase in cut-off ratio will a. increase b. decrease c. independent d. increase or decrease depending upon other factors ANSWER b. decrease 33. Combustion in compression ignition engine is a. homogeneous b. heterogeneous c. laminar d. turbulent ANSWER b. For an air-standard diesel cycle, the effect is quite clear. But first, let us look at the expression for thermal efficiency: Here r is the compression ratio, gamma is the ratio of specific heats, alpha is the cut-off ratio. Keeping r and gamma co..

- In general, engines using the Diesel cycle are usually more efficient, than engines using the Otto cycle. The diesel engine has the highest thermal efficiency of any practical combustion engine. Low-speed diesel engines (as used in ships) can have a thermal efficiency that exceeds 50%. The largest diesel engine in the world peaks at 51.7%
- ⇒ The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will. increase decrease be independent may increase or decrease depending on other factors ⇒ The pressure and temperature at the end of compression stroke in a petrol engine are of the order of. 4 - 6 kg/cm2 and 200 - 250Â°
- 236. The thermal efficiency of a semi-diesel cycle having fixed compression ratio and fixed quantity of heat, with increase in pressure ratio will (a) increase (b) decrease (c) remain unaffected (d) increase/decrease depending upon engine capacity (e) first increase and then decrease. 245. The termal efficiency of a petrol engine at design load.
- imum when compression is. Isothermal; Adiabatic; Isentropic; Polytropi

Derive an expression for efficiency of diesel cycle. written 4.3 years ago by Paras Gada ♦ 500: modified 19 months ago by Sanket Shingote ♦ 520: diesel cycle. ADD COMMENT • FOLLOW • SHARE • REPORT 1 Answer. 1. Let compression ratio,r=$\frac{v_1}{v_2}$ , and cut-off ratio,ρ=$\frac{v_3}{v_2}$ i.e.$\frac{Volume at cut-off}{clearance. Derive an analytic equation for the thermal efficiency of a diesel cycle based on a cold air standard analysis T-s diagram for otto cycle - (source - Thermodynamics by Cengel and Boles) Compression ratio =[math] r = \displaystyle \left (\frac{Total\,\,volume}{Clearance. Achieving this goal would mean the creation of a perfectly efficient engine, and we would say that it has a thermal efficiency of 100%. Defining the percentage efficiency of any engine is therefore pretty obvious - simply take the ratio of the work extracted to the heat supplied So the compression ratio of the engine is 1000:100 or 10:1. It is proved that the greater the compression ratio more the power output of the engine. A compression ratio of the diesel engine is much higher than the petrol engine. The petrol engine has a compression ratio of 10:1 to 14:1. The diesel engine has a compression ratio of 18:1 to 23:1

- 3. 6 Diesel Cycle The Diesel cycle is a compression ignition (rather than spark ignition) engine. Fuel is sprayed into the cylinder at (high pressure) when the compression is complete, and there is ignition without a spark. An idealized Diesel engine cycle is shown in Figure 3.12
- 20. The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will A.Increase B.Decrease C.Be independent D.May increase or decrease depending on other factor
- The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will. A. Increase. B. Decrease. C. Be independent. D. May increase or decrease depending on other factors. Answer & Solution Discuss in Board Save for Later 28. Which is more viscous lube oil?.
- Thermal Efficiency of the Otto cycle: An Otto cycle having a compression ratio of 9:1 uses air as the working fluid. Initially P1 = 95 kPa, T1 = 17 oC, and V 1 = 3.8 liters. During the heat addition process, 7.5 kJ of heat are added. Thermal efficiency of the Diesel cycle
- 23. The thermal efficiecny of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will (a) increase (b) decrease (c) be independent (d) may increase or decrease depending on other factors (e) none of the above. Ans: b. 24. Pick up the wrong statement (a) 2-stroke engine can run in any direction (b) In 4-stroke engine.

Thermal efficiency of the ideal Otto cycle as a function of compression ratio (k = 1.4).. In SI engines, the compression ratio is limited by autoignition or engine knock. The thermal efficiency of the Otto cycle increases with the specific heat ratio k of the working flui 236. The **thermal** **efficiency** **of** **a** semi-**diesel** **cycle** **having** **fixed** **compression** **ratio** and **fixed** quantity of heat, with increase in pressure **ratio** will (**a**) increase (b) decrease (c) remain unaffected (d) increase/decrease depending upon engine capacity (e) first increase and then decrease. 245. The termal **efficiency** **of** **a** petrol engine at design load. * Q17*. A diesel engine is usually more efficient than a spark ignition engine because (a) diesel being a heavier hydrocarbon, releases more heat per kg than gasoline (b) The air standard efficiency of diesel cycle is higher than the Otto cycle, at a fixed compression ratio [GATE-2003

** 9-51 An ideal diesel engine has a compression ratio of 20 and uses air as the working fluid**. The state of air at the beginning of the compression process is 95 kPa and 20°C. If the maximum temperature in the cycle is not to exceed 2200 K, determine (a) the thermal efficiency and (b) the mean effective pressure As the cutoff ratio of a Diesel cycle increases for fixed compression ratio, the thermal efficiency decreases

* Q6*. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called. a) Net efficiency. b) Efficiency ratio. c) Relative efficiency. d) Overall efficiency . Q7. Compression ratio of LC. Engines is. a) The ratio of volumes of air in cylinder before compression stroke and after compression strok The air standard cycle efficiency is A. 38.3 % B. 39.8 % C. 60.2 % D. 61.7 % ANSWER D. 61.7% Q.8 The thermal efficiency of a diesel cycle having fixed compression ratio with increase in cut-off ratio will A. increase B. decrease C. independent D. increase or decrease depending upon other factors ANSWER B. decrease Q. 9 Specific fuel consumption.

For an air standard engine with γ= 1.4, compression ratio rC= 15 and expansion ratio rE= 5, this gives an ideal diesel efficiency of 56%. For a diesel cycle for which γ= with compression ratio rC= and expansioin ratio rE= • In a Diesel cycle, the compression ratio is 15. Compression begins at 0.1 Mpa, 40. o. C. The heat added is 1.675 MJ/kg . Find (a) the maximum temperature in the cycle, (b) work done per kg of air (c) the cycle efficiency (d) the temperature at the end of the isentropic expansion (e) the cut -off ratio and (f) the MEP of the cycle ** The thermal efficiency of a semi-diesel cycle having fixed compression ratio and fixed quantity of heat, with increase in pressure ratio will_____? A**. increase. B. decrease. C. remain unaffected. D. increase/decrease depending upon engine capacity. E. first increase and then decreas Thermal efficiency increases as the compression ratio increases only for the otto and diesel cycle, not dual cycle petrol (gasoline, Otto cycle) and diesel (Diesel cycle) engines have an expansion ratio equal to the compression ratio. Some engines, which use the Atkinson cycle or the Miller cycle achieve increased efficiency by having an expansion ratio larger than the compression ratio. Diesel engines have a compression / expansion ratio between 14:1 to 25:1

- Figure 21.3 shows the variation of air standard cycle efficiency with compression ratio, and shows the range of this ratio for spark-ignition and diesel engines. It is clearly desirable to use as high a compression ratio as possible. Also shown is the approximate indicated thermal efficiency to be expected from gasoline and diesel engines of 2.5 liter swept volume
- Mechanical Engineering MCQS questions and answers for different type of tests in government and private sector Language: Englis
- What will be the effect on the efficiency of a diesel cycle having a compression ratio of 20 and a cut-off takes place at 8% of the swept volume, if the C v increases by 1%. Take C v = 0.717 kJ/kg K and R = 0.287 kJ/kg K. Ans:-1.197% 5. A petrol engine using a compression ratio 7 and air-fuel ratio of 15:1 has the pressur
- From the above equation, it is observed that, the thermal efficiency of the diesel engine can be increased by increasing the compression ratio, R o, by decreasing the cut-off ratio, r c, or by using a gas with large value of γ

The ideal Otto cycle efficiency is shown as a function of the compression ratio in Figure 3.11. As the compression ratio, , increases, increases, but so does . If is too high, the mixture will ignite without a spark (at the wrong location in the cycle). 3. 5. 2 Engine work, rate of work per unit enthalpy flux The non-dimensional ratio of work. An ideal diesel cycle has a compression ratio of 16 to 1. The maximum cycle temperature is 1700°C and the minimum cycle temperature is 15°C. Calculate: i. the specific heat transfer to the cycle ii. the specific work of the cycle iii. the thermal efficiency of the cycle 34 35. Dual cycle gives a better approximation to a real engine Most petrol (gasoline, Otto cycle) and diesel (Diesel cycle) engines have an expansion ratio equal to the compression ratio. Some engines, which use the Atkinson cycle or the Miller cycle achieve increased efficiency by having an expansion ratio larger than the compression ratio Thermal efficiency of the ideal Otto cycle An Otto cycle having a compression ratio of 9:1 uses air as the working fluid Which engine's thermal efficiency is greater for the same power output and same compression ratio: 2 stroke or 4 stroke, and why? 2 stroke engine versus 4 stroke engine Engineering Thermodynamic

The minimum and maximum temperatures in the cycle are 27ºC and 1600 K. Determine thermal efficiency of cycle and also show it on T-s and P-V diagram. Q.2] In a Diesel engine during the compression process, pressure is seen to be 138 kPa at 1/8th of stroke and 1.38 MPa at 7/8th of stroke The gross-indicated thermal efficiency was calculated based on the cycle work by in-cylinder pressure and volume traces only during compression and expansion strokes. The brake thermal efficiency was further improved using a piston cavity having higher geometric compression ratio than the baseline value of 18.0. Recall that in the ideal Diesel cycle the extremely high compression ratio (around 18:1) allows the air to reach the ignition temperature of the fuel. The fuel is then injected such that the ignition process occurs at a constant pressure engine operates on the ideal Diesel cycle with a compression ratio of 19. The air is at 95 kPa and 67 oc at the beginning of the compression process and the engine speed is 1750 IVIn. The engine uses light Diesel fuel with a heating value of 42,500 kJ/kg, an air-fuel ratio of 28, and a combustion efficiency of 98%. Using constant specific heat

thermal efficiency due to the pumping work. The effect of higher compression ratio is very small for the same load because of the 4500 ,Dm (WID CRANK CASE PUMPING I lool COMPRESSION RATIO Fig. 7 Relationship between the Compression Ratio and the Mechanical Loss 6 8 10 12 74 COMPRESSION RATIO 45W rum BMEP 200 kPm 20 . FlJEL.AI 1) The thermal efficiency of a two stroke petrol engine as compared to that of a four stroke petrol engine for same output, same speed and same compression ratio is a) same b) less c) more d) None of the above View Answer / Hide Answe Thermal efficiency From 2, 3 and 4 all temperatures can be expressed in terms of T3. Otto and Diesel Cycle Comparison For given rc higher thermal efficiency is obtained via higher compression ratio rv and for a given rv higher thermal efficiency is achieved by lowering the cut-off ratio r * The only way to overcome this deficiency is to use higher compression ratios in case of real engines to offset the effect of lower efficiency*. Just to give an example the thermal efficiency of a diesel cycle engine having a compression ratio of 14 would be greater than an Otto cycle engine having compression ratio of 7 due to this offset effect The Air Standard Diesel cycle is the ideal cycle for Compression-Ignition (CI) reciprocating engines, first proposed by Rudolph Diesel over 100 years ago. The following link by theKruse Technology Partnership describes the four-stroke diesel cycle operation including a short history of Rudolf Diesel. The four-stroke diesel engin

9(a). Derive the air standard efficiency of diesel cycle in terms Compression & cut-off ratios. (6) 9(b). Draw the actual and theoretical PV diagrams for 4 stroke CI engine and explain them.(10) 10. A 4 stroke SI engine has the compression ratio of 6 and the swept volume of 0.15m³.Pressure and temperature at the beginning o The efficiency assumes that no other changes are made when the compression ratio is altered, such as quench, valve shrouding, piston dome masking, etc. and that fuel of sufficient octane is used to permit the best ignition advance. To use this table: locate the original compression ratio (C-Ratio) in the 1st, 3rd or 5th row across in terms of qin/(cpT1rk-l) for an air-standard Diesel cycle. -67 Develop an expression for the thermal efficiency of a — r where rc is the cut- Jal cycle when operated such that r ff ratio and r is the pressure ratio during the constant-volume addition process. What is the thermal efficiency of such lgine when the compression ratio is 20 and A large single-cycle gas turbine typically produces for example 300 megawatts of electric power and has 35-40% thermal efficiency. Modern Combined Cycle Gas Turbine (CCGT) plants, in which the thermodynamic cycle of consists of two power plant cycles (e.g. the Brayton cycle and the Rankine cycle), can achieve a thermal efficiency of around 55%

35. An idealized diesel engine operates in a cycle known as the air-standard diesel cycle shown in Figure P22.35. Fuel is sprayed into the cylinder at the point of maximum compression, B. Combustion occurs during the expansion B ( C, which is modeled as an isobaric process. Show that the efficiency of an engine operating in this idealized. Compression ratio. Compression ratio influences the thermal efficiency of an engine. Theoretically the thermal efficiency increases as the compression ratio is increased. The minimum value of a diesel engine compression ratio is determined by the compression required for starting, which, to large extent is dependent on the type of fuel used The use of NTSOME in a VCR engine at higher compression ratio results in shorter ignition delay, smaller rate of pressure rise, higher heat release rate and insignificant decrease in mass fraction burnt when compared to that of diesel operation. At high compression ratio, the NTSOME was found to exhibit maximum thermal efficiency Most engines use a fixed compression ratio, however a variable compression ratio engine is able to adjust the compression ratio while the engine is in operation. The first production engine with a variable compression ratio was introduced in 2019. Variable compression ratio is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation An ideal Diesel cycle has a maximum cycle temperature of 2300°F and a cutoff ratio of 1.4. The slate of the air at the beginning of the compression is P, = 14.4 psia and T 1 = 50°F. This cycle is executed in a four-stroke, eight-cylinder engine with a cylinder bore of 4 in and a piston stroke of 4 in

Thermal efficiency of the ideal Otto cycle as a function of compression ratio (k = 1.4). The thermal efficiency of the Otto cycle increases with the specific heat ratio k of the working fluid. In SI engines, the compression ratio is limited by autoignition or engine knock The Diesel cycle is less efficient than the Otto cycle when using the same compression ratio. However, practical Diesel engines are 30% - 35% more efficient than gasoline engines. [7] This is because, since the fuel is not introduced to the combustion chamber until it is required for ignition, the compression ratio is not limited by the need to. In dual cycle, injection of fuel starts little before piston reaches TDC. So cut-off ratio of dual cycle is less than that of diesel cycle so its efficiency will be higher than diesel cycle for same compression ratio. For r p =1, efficiency becomes equal to that of diesel cycle. For r c =1, efficiency becomes equal to that of Otto cycle. 3

The most efficient installation was a Japanese company, with 59.1% verified on an M701G2 gas turbine at the 1500 MW Tokyo Electric Kawasaki power station in Japan. Since then GE claimed on the 28th of April 2016, a world record for thermal efficiency, with 62.22%, for a combined cycle plant, in France The larger 1.3-liter Atkinson cycle engine uses a high compression ratio (13.5) and all the same engine innovations to achieve thermal efficiency of 38 percent B. Diesel Engine Cycle Diesel engine works on diesel cycle comprises of two isentropic, one isochoric and one isobaric process. For 1 kg of air in the cylinder, the efficiency analysis of the cycle can be made as given below. The efficiency may be expressed in terms of any two of the following three ratios c Compression ratio, 2 1 V V rk = (6

(f) To investigate the effects of varying compression ratio on the thermal efficiency, plot the thermal efficiency for compression ratios ranging from 5 to 25. Diesel cycle The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called _____ a) net efficiency b) efficiency ratio The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will _____ a) increase b) decrease c) be independent d) none of the mentioned View Answer

: - Present work was performed in a 3.7kW, 4 stroke single cylinder, water cooled, variable compression ratio, diesel - engine fueled with the different blends of ethanol and diesel fuel run on three different compression ratios of 17, 17.5 and 18 Derive a formula for the efficiency of the Diesel cycle, in terms of the compression ratio V l /V 2 and the cutoff ratio V 3 /V 2 . Show that for a given compression ratio, the Diesel cycle is less efficient than the Otto cycle. Evaluate the..

cycle with regeneration. Thermal efficiency of the ideal Brayton cycle with and without regeneration. The thermal efficiency depends on the ratio of the minimum to maximum temperatures as well as the pressure ratio. Regeneration is most effective at lower pressure ratios and low minimum-to- maximum temperature ratios The mean effective pressure of the diesel cycle having a fixed compression ratio will increase if the cut-off ratio. Correct-Skipped. Incorrect! Missed Answer. 13 of 35 - ic engines. Save Saved. The thermal efficiency of the ideal diesel cycle is given by equation____ Where, ρ = Cut off ratio, r = Compression ratio. Correct-Skipped. Incorrect. * The thermal efficiency of a semi-diesel cycle having fixed compression ratio and fixed quantity of heat, with increase in pressure ratio will (a) increase (b) decrease (c) remain unaffected (d) increase/decrease depending upon engine capacity (e) first increase and then decrease*. 245. The termal efficiency of a petrol engine at design load is.

The efficiency of a Brayton engine can be improved by: Increasing pressure ratio, as Figure 1 above shows, increasing the pressure ratio increases the efficiency of the Brayton cycle. This is analogous to the increase of efficiency seen in the Otto cycle when the compression ratio is increased. However, practical limits occur when it comes to. Assertion (A): For a given compression ratio, the thermal efficiency of the Diesel cycle will be higher than that of the Otto cycle. Reason(R): In the Diesel cycle, work is also delivered during heat addition heat-addition process, (b) the thermal efficiency, and (c) the mean effective pressure. Answers: (a) 1724.8 K, (b) 56.3 percent, (c) 675.9 kPa 9-47 An air-standard Diesel cycle with a compression ratio of 16 and a cutoff ratio of 2 is considered. The temperature after the heat addition process, the thermal efficiency

The expansion ratio of the Atkinson cycle engine is greater than the compression ratio, which means it's more efficient. It has less power, but when paired with an electric motor, the two. Effect and typical ratios. A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency.This occurs because internal combustion engines are heat engines, and higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer. The diesel engines are known for providing high power output which is due to the high compression ratio of the diesel engine, as we know higher the CR higher will be the thermal efficiency or work output. A diesel engine with high CR provides high fuel economy due to the higher thermal efficiency provided by the high compression combustion Thermal efficiency of the ideal Otto cycle as a function of compression ratio (g=1.4) The thermal efficiency of the Otto cycle increases with the specific heat ratio, g of the working fluid. Air standard Diesel cycle Diesel cycle on (a) P-v diagram (b) T-s diagra Compression ratio. The higher the compression ratio the higher the thermal efficiency. As in spark ignition or gasoline engines the compression ratio is limited by pre-ignition (not in compression ignition or diesel engines), the diesel engines are about 30% more efficient than gasoline engines. Drag of the vehicl

The turbine inlet temperature is very crucial for the higher compression ratio. The overall thermal efficiency at high compression ratio increases from 54.8% to 61.3% with the increase of the turbine inlet temperature from 1150 to 2050K facilitate the design of a combined cycle with higher efficiency and output work. Mathematical calculations and simple graphs in ms excel, and auto cad has been carried out to study the effects and influences of the above mentioned parameters on the efficiency and work output. compression ratio, heat supplied) that are influenced i The thermal efficiency of the Otto cycle is 65.20%. As noted, the thermal efficiency mainly depends on the ratio of compression of the engine and the type of liquid. Thus, it can be concluded that engines with a higher compression ratio have a high thermal efficiency. Effectiveness. Zepahonikito wawebehudo wasubugapu ni kevijorufu forisicopi.

- role on the power output and the
**thermal****efficiency**. They reflect the performance characteristics of an irreversible**Diesel****cycle**engine. The variations of the power output with respect to the**compression****ratio**and the specific heat**ratio**are indicated in Figure 2. It can be seen that the power output versus the**compression****ratio**characteristic i - The effect of compression ratio It can be shown that the higher the compression ratio, the higher the thermal efficiency. If the effect of heat capacity dependence on temperature is considered, the thermal efficiency still increases as the compression ratio is raised. However, the simple relationship above does not hold any longer
- It is dependent on engine efficiency, transmission design, and tire design. The diesel engine has the highest thermal efficiency (engine efficiency) of any practical internal or external combustion engine due to its very high expansion ratio and inherent lean burn which enables heat dissipation by the excess air. Microturbines have around 15% efficiencies without a recuperator, 20 to 30% with.
- ation of Equation (9) and Figure 7 that for a given compression ratio, the ideal Diesel cycle efficiency will always be less than that for the ideal Otto cycle and as more heat is added (i.e., the engine produces more work) the efficiency of the ideal Diesel cycle will decrease
- RDE compliant VCRi-Miller engines have an optimum power density of 80-120 kW/l, while fixed-compression ratio engines operate at only 65-80 kW/l

- (A) Diesel being a heavier hydrocarbon, release more heat per kg than gasoline (B) The air standard efficiency of diesel cycle is higher than the Otto cycle, at a fixed compression ratio (C) The compression ratio of a diesel engine is higher than that of an S.I engine (D) Self ignition temperature of diesel is higher than that of gasoline. GATE.
- DIESEL CYCLE ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET 28. A diesel engine has a compression ratio of 15 and heat addition at constant pressure takes place at 6% of stroke. Find the air standard efficiency of the engine. Take γ of air as 1.4. ME 6701 POWER PLANT ENGG. S.BALAMURUGAN AP/MECH AAACET 29
- A six-cylinder, four-stroke, 3.2-L compression-ignition engine operates on the ideal diesel cycle with a compression ratio of 19. The air is at 95 kPa and 67°C at the beginning of the compression process and the engine speed is 1750 rpm

It is also shown that, in certain cases, thermal efficiency and net work output can exceed the basic cycle and that external heat addition may be less than the basic cycle. Performance curves are provided for Otto and Diesel cycle regeneration with fixed Tmax and variable compression ratio The results demonstrated that the indicated gross thermal efficiency could be increased by not cooling the piston, by using high dilution, and by optimizing in-cylinder fuel stratification with two fuels of large reactivity differences. The best results achieved gross indicated thermal efficiencies near 60% A diesel engine has a compression ratio of 20:1 with an inlet of 95 kPa, 290 K, state 1, with volume 0.5 L. The maximum cycle temperature is 1800 K. Find the maximum pressure, the net specific work and the thermal efficiency The efficiency η of the cycle is defined as \[\eta = \frac{W}{Q_{sup}},\] where W is the work performed by the gas during one cycle minus the work performed by the external forces (in the diagram it is represented by the surface of the area defined by the lines of the cycle!) and Q sup is the heat supplied to the system during the cycle.. The work W can be calculated by using the relationship.

constant pressure in the Diesel cycle. 9-47 An air-standard Diesel cycle has a compression ratio of 16 and a cutoff ratio of 2. At the beginning of the compression process, air is at 95 kPa and 27°C. Accounting for the variation of specific heats with temperature, determine (a) the temperature after the heat-addition process, (b) the thermal. L41v, the thermal efﬁciency of this cycle can be expressed ash Otto =- - -1 ()( )TTT T 413 2, which becomes11-()r ()g-1 for a calorically perfect ideal gas. The compression ratio is deﬁned as r =vv 12[3]. 1.2.3. Diesel cycle. The standard Diesel cycle is an idealized cycle consisting of tw Thermal Efficiency Derivation. The overall efficiency for the cycle (indicated thermal ) is given by: since: Figure 5. Thermal efficiency as a function of r: The following relationship for the efficiency can be developed and plotted against the compression ratio in Figure 5. A typical value for an air/fuel mixture is k = 1.35 higher specific heat ratios leading to increased thermal efficiency. It has higher flame speed and hence faster energy release. And at stoichiometeric mixtures, acetylene engines could closely approach thermodynamically ideal engine cycle. High selfignition temperature of acetylene allows larger compression ratios than diesel engines do

The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be Scavenging air in diesel engine means In petrol engine, using a fixed octane rating fuel and fixed compression ratio, supercharging will _____ the knocking tendency.. The thermal efficiency of the ideal Diesel cycle as a function of compression and cutoff rates 8-18 The Net Work of the Brayton Cycle For fixed values of Tmin and Tmax, efficiency of the ideal Otto cycle is where r is the compression ratio and k is the specific heat ratio C p /C v In the 1.3-liter engine, a 13.5 compression ratio makes up for some of the lost compression through the engine's cycle--in theory, the engine should perform similarly to a regular 1.3-liter unit The simulation study was based on continuously varying compression ratio from 20:1 at low load to 10:1 at high load. This approach is compared to a fixed compression ratio (FCR) engine with dual (intake and exhaust) VVT and a 10.5 compression ratio. Both engines have a displacement of 1.1 L and have 3 cylinders [3517]. Figure 20(b) shows the.