# Why is the thermal efficiency of the auto cycle greater than that of the diesel engine? What is the reason for the increase? (2023)

Engineering Leisure

Respondent:

The thermal efficiency of the Otto cycle is greater than that of the diesel engine due to the larger area under the PV diagram.

The reason for increasing the use of diesel engine instead of Otto cycle is that the compression ratio of diesel engine is much higher than that of Otto cycle. Therefore, with the same compression ratio, the diesel engine is more efficient, making it more feasible to use it in most operating points. As a practical approach, diesel engines are more often used instead of the Otto cycle.

Explanation:

The thermal efficiency of the Otto cycle is greater than that of the diesel engine due to the fact that the area under the PV diagram is larger because the Otto cycle has heat addition at constant volume instead of constant pressure, which increases the amount of work the engine can do to produce during expansion increasing the mean effective pressure.

whereas in the diesel engine the heat addition takes place at constant pressure, which is proportional to the heat addition while the piston moves down the expansion stroke. Therefore, some of the potential thermal energy is not fully utilized in the expansion path of a diesel engine.

The reason for the increase in the use of the diesel engine in the Otto cycle has to do with the fact that, in the practical world, the compression ratios of the diesel engine are much higher than the Otto cycle. Therefore, with the same compression ratio, the Deisel engine is more efficient at most operating points, making it more viable to use even at low loads, especially as they operate both without throttle and without combustion. Diesel engines are also more efficient at near or equal to full load as they are still running at light load, while Otto engines are running at full load. Here's why. When we talk about real phenomenon, diesel engines are used more than Otto cycle.

## Related questions

For a 2 Vpp signal that fits the input range of the ADC, find the SQNR for: a) an 8-bit ADC with an input range of 1 V to 6 V b) a 9-bit ADC with an input range of 0 V to 4 V

Respondent:

Se Number of bits = n

Afterward,

SNR = 20 log x rms signal / rms noise

SNR = 6,02n + 1,75db

The SNR depends only on the No pf bit

Α) Number of bits (n) = 8

SNR = 6,02 × 8 + 1,75

SNR = 49,92db

THE

SNR = 50db

Β) Number of bits (n) = 9

SNR = 6,02 × 9 + 1,75

SNR = 55,94db

THE

SNR = 56db

If we increase one bit by one, the SNR will increase by 6db

If n(↑) to 1 bit the SNR increases by 6db

On a large lake without waves, how far from shore is a sailboat when the top of its 7-meter mast disappears from the view of a person whose eye level is 1.7 meters above the water's edge? Express your answer to three significant figures and include appropriate units.

Respondent:

D = 15,202 km

Explanation:

Given:

- The height of the sail of the sailboat under the wave h_1 = 7 m

- The viewing level above the water's edge h_2 = 1.7 m

Come across:

how far from shore is a sailboat

Solution:

- The distance from the shore (person) to the sailboat in a lake with waves is given by the following expression:

D = sqrt ( h_1 / 0,0675) + sqrt ( h_2 / 0,0675 )

Where, D is the curved distance along the Earth's surface:

- Enter prices and rate:

D = square(7/0.0675) + square(1.7/0.0675)

D = 10.18350 + 5.01848

D = 15,202 km

One type of lighting system consists of rows of fluorescent lamps and a ceiling that transmits the light. For this system to be effective, the surfaces above the skylight must be ____.

Respondent:

For this system to be effective, the surfaces above the light ceiling must be white so that all the emitted light is reflected.

Explanation:

White surfaces reflect light with almost 100% efficiency, which ensures that transmitted light is not absorbed.

So if one type of lighting system consists of rows of fluorescent lamps and a ceiling that will transmit the light. For this system to be effective, the surfaces above the light ceiling must be white so that all the emitted light is reflected.

Technician A says that solid state circuits can be damaged if the load voltage becomes too high. Technician B says that damage can occur if the vehicle is left running with the battery disconnected. Who is right?

Respondent:

Technicians A and B are both correct

Explanation:

A solid state circuit is usually made of semiconductor materials. When a higher-than-normal voltage is introduced into the circuit, it can cause overheating and damage to the various semiconductor materials that make up the solid-state circuit. So Technician A is right.

Unplugging a car breaker while the vehicle is running can damage the car's electronics. In addition to supplying electricity to the car, the battery also causes short circuits, spikes and transients to ground. If you remove the battery while your vehicle is running, the spikes and transients will simply transfer to your vehicle's electronics and destroy them. So Technician B is also right.

A cylindrical specimen of this alloy, 12.7 mm in diameter and 250 mm long, is stretched in tension and elongated 7.6 mm. Based on the information provided, is it possible to calculate the magnitude of the load required to produce this change in length? If so, calculate the load. If not, explain why.

(Video) Why Diesel Engines Lose Power & Efficiency Over Time

Respondent:

Condition 2 is true.

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we are unable to calculate the charge with the information provided.

According to the above values, Condition 2 is satisfied, so we cannot find the load with the given information because the deformation of the material is in the plastic region.

Explanation:

To check whether we can find the charge or not, we need to check the following conditions:

Condition 1:

If this condition holds, we can calculate the load.

Condition 2:

\epsilon_{yield}" alt="\epsilon_{test}>\epsilon_{yield}" align="absmiddle" class="latex-formula">

If this condition is true, we cannot calculate the load with the information provided.

Calculator:

Calculator:

Here's why:

Condition 2 is true.

\epsilon_{yield}" alt="\epsilon_{test}>\epsilon_{yield}" align="absmiddle" class="latex-formula">

According to the above values, Condition 2 is satisfied, so we cannot find the load with the given information because the deformation of the material is in the plastic region.

Some designers suggest using speech recognition in a telephone menu system. This would allow users to interact with the system by speaking instead of pressing buttons on the dial pad. Give two arguments for and three arguments against the proposition.

Designers suggest that speech recognition enables spoken interaction or conversation and spoken prompts or commands.

Explanation:

Speech recognition is used when the user has physical disabilities and the hands are busy, the eyes are busy and the user cannot read.

We can save time by using speech recognition system. Users are notified based on available actions.

The problems the speech recognition system faces are in the noisy environment, with bad microphones and the commands have to be learned and remembered.

The other obstacle is that debugging is time-consuming. Speech output has slow space for speech output provides privacy in public places. The downside is that it contains a lot of information.

Explain why test-first development helps the developer better understand the system requirements. What are the potential difficulties with developing the first test?

Respondent:

Because test-first development provides a better and clearer relationship between developer code requirements and computer system requirements.

It gives the programmer a better understanding of the required writing patterns to write the test for the computer system.

possible difficulties

(1) some test developments are difficult to write step by step;

(2) some developers no longer care about testing;

(3) Requires additional time and cost for effective implementation.

Explanation: Test-first development is a method of software development where the developer is expected to test the program while it is being developed to ensure that all potential bugs or threats to the successful use of the system are addressed.

Test-first development gives the developer a better understanding of the software or language tests as they are tested as their development continues, but also presents some difficulty as some of them are difficult to write step by step. It also requires sufficient time and cost to be effective.

Smoke rises from a chimney on a windy day and produces a visible pattern. Does this pattern represent a path line or a stripe line? Under what conditions can the trajectory line and danger line be the same?

Respondent:

route line

Explanation:

- Smoke coming out of the chimney on a day with variable winds would be closer to a path line. Think of a "gray" smoke particle injected into the air at every moment and following a continuous "path" along the fluid flow.

- A line trace focuses on fluid particles that have passed a station or fixed point. At some point, the position of all these particles is marked and a line is drawn through them.

- The fairway line and track line may coincide under flow conditions to be steady, i.e. the rate of change of airflow is continuous and does not change with time in a day, i.e. changing winds or any discontinuity is removed.

C-clamp threaded axle cable is 0.05 in. and the average thread radius is r = 0.15 in. Assume that mus = 0.18. What torque must be applied to the shaft to exert a force of 30 lb on the trapped object?

The part of the question that was omitted is shown in bold

C-clamp threaded axle cable is 0.05 in. and the average thread radius is r = 0.15 in. Assume μs = 0.18 and μk = 0.16. What torque must be applied to the shaft to exert a force of 30 lb on the trapped object?

Respondent:

C = 0.967 pol. pound

Explanation:

Given the:

C-clamp threaded axle cable is 0.05 in.

∴ screw pitch = 0.05 in

Assuming:

(μs)= 0.18 which implies the coefficient of static friction

(μk) = 0.16 (coefficient of kinetic friction)

Force = 30 lbs

What torque must be applied to the shaft to exert a force of 30 lb on the trapped object?

Determine the pair (C) to be applied. we use the expression:

C = Fr tan (+ )

where; F = force

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= angle of kinetic friction

= tilt angle

NOW, let's take one after the other.

The coefficient of static friction and kinetic friction. we can solve for their corresponding angles, so we have:

angle of static friction ()

() =

() = 10.204°

Angle of kinetic friction ()

= 9,0903°

To determine the angle of inclination (); we apply the expression:

() =

() =

() =

() = 3,0368°

We have our parameters to solve for Pair (C). so we have:

C = Fr tan (+ )

replacing our values. We have:

C = (30 × 0.15) tan (9.0903 + 3.0368)

C = 4.5 × tan (12.1271)

C = 4,5 × 0,2148761968

C = 0,96669428854 pol.lb

C = 0.967 pol. pound

Therefore, a pair of 0.967 in. lb must be applied to the shaft to exert a force of 30 lb on the trapped object.

Technician A says that some multiplexing systems use a data bus consisting of a twisted pair of wires. Technician B says that some multiplexing systems use a single-wire data bus. Who is right?

Answer: Both Technician A and Technician B are correct.

Explanation:

The multiplexing system makes it possible to communicate within several separate units through the use of one (or two) cables. In this case, the data bus has a single wire. So technician B is right.

In addition, the data backbone of a multiplex system, called the twisted-pair backbone, consists of twisted-pair wires that are twisted together to reduce susceptibility to EMI. Therefore Technician B is also correct.

The compartments of these tanks are closed and filled with air. Gauge A shows 207 KPa. Gauge B registers a vacuum of 254 mm of mercury. What will the C-meter read if it is connected to compartment 1 but inside compartment 2? Barometric pressure is 101 kPa absolute. Hint: Changes manometer B from mm Hg to KPa.

254 mm of mercury is 33.86 kPa.

Respondent:

C meter=240.86 KPa

Explanation:

we are given:

254 mm of mercury is 33.86 kPa =.

Barometric pressure==101 KPa

Caliber A=207 KPa=

Now:

C= promise

Apartment 2:

calculated as:

=-

=101 KPa-33,86 KPa

=67,14 KPa.

Apartment 1:

calculated as:

=+

=101 KPa+207 KPa

=308 KPa

C= promise

Caliber C=308 KPa-67.14 KPa

C meter=240.86 KPa

Air is compressed adiabatically from p1 1 bar, T1 300 K to p2 15 bar, v2 0.1227 m3/kg. The air is then cooled at constant volume to T3 300 K. Assuming ideal gas behavior and neglecting kinetic and potential energy effects, calculate the work for the first process and the heat transfer for the second process, each in kJ per kg of air . Solve the problem in two ways:

Respondent:

Work done for the adiabatic process = -247873.6 J/kg = -247.9 KJ/kg

Heat transfer for constant volume process = - 244.91 KJ/kg

Explanation:

For the first state,

P1 = 1 bar = 105 Pa

T1 = 300 K

V1 = ?

second state

P2 = 15 bar = 15 × 105 Pa

T2 = ?

V2 = 0.1227 m3/kg

third estate

P3 = ?

T3 = 300K

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V3 = ?

We require the work for step 1-2 (which is adiabatic)

And heat transferred for steps 2-3 (which is isothermal/constant volume)

The work done for an adiabatic process is given by

W = K(V21-ʸ - V11-ʸ)/(1 - γ)

where γ = ratio of specific heats = 1.4 for air, since air is mainly diatomic

K = PVʸ

Using state 2 to calculate k

K = P2V2ʸ = (15 × 105) (0,1227)1•4 = 79519,5

We also need V1

P1V1ʸ = P2V2ʸ = K

P1V1ʸ = K

(105) (V11•4) = 79519,5

V1 = 0.849 m3/kg

W = K(V21-ʸ - V11-ʸ)/(1 - γ)

W = 79519,5 [(0,1227)-⁰•4 - (0,849)-0•4]/(1 - 1,4)

W = (79519,5 × 1.247)/(-0,4) = - 247873,6 J/kg = - 247,9 KJ/kg

To calculate the heat transferred for the constant volume process

Heat transferred = Cᵥ (ΔT)

where Cᵥ = specific heat capacity at constant volume for air = 0.718 KJ/kgK

ΔT = T3 - T2

We need to calculate for T2

Since air is an ideal gas,

PV = mRT

T = PV/mR

no state 2,

V/m = 0,1227 m³/kg

P2 = 15 bar = 15 × 105 Pa

R = gas constant for air = 287.1 J/kgK

T2 = 15 × 105 × 0,1227/287,1 = 641,1 K

Q = 0,718 (300 - 641,1) = - 244,91 KJ/kg

10. Aluminum-Lithium (Al-Li) alloys were developed by the aircraft industry to reduce weight and improve the performance of this aircraft. A commercial aircraft skin material with a density of 2.47 g/cm3 is desired. Calculate the required Li concentration (% by weight).

Respondent:

C_Li=2.3%

Explanation:

solution:

We know that the average density of a two-component alloy is given by:

ρ_méd=100/(C_1/ρ_1+C_2/ρ_2)

2.47 g/cm^3 = 100/(C_Li/ρ_Li+(100-C_Li)/ρ_aL)

solving for C_Li we get,

C_Li=2.3%

Argon is compressed in a multimode process with n = 1.2 from 120 kPa and 10°C to 850 kPa in a piston-cylinder apparatus. Determine the work produced and the heat transferred

Respondent:

W=-109,12 kJ/kg

Q=-76,34 kJ/kg

Explanation:

The work required W will be calculated using the work equation for the multimodal process and the heat transfer Q will be calculated using the energy balance equation.

Before the calculations, we must first determine the final temperature T2. We will do this using the given initial temperature T1 = 10°C, the given initial pressure p_1 = 120 kPa and final pressure p_2 = 800 kPa, and the multimodal index n = 1.2. Before calculating, we need to express the temperature in units of K.

T1 = 10°C + 273 K = 283 K

T2 = ((p_2/p_1)^(n-1)/n)* T1

T2 = 388 K

Now we can use the heat capacity C_v, = 0.3122 kJ/kg K and the temperatures T1 and T2 to determine the internal energy change ΔU.

ΔU = C_v*(T2-T1)

ΔU = 32,78 kJ/kg

to specify the task we will also need the initial specific volume v1 and the final v2. The initial specific volume v1 can be determined from the ideal gas equation. For the calculation we will need the initial pressure p_1, the temperature T1 and the specific gas constant R = 0.2081 kJ /kg K.

v1=R*T1/p_1

v1=0,4908 m^3/kg

For the final specific volume, we must replace the initial temperature and pressure with the final ones.

v2=R*T2/p_2

v2=0,1009 m^3/kg

The work W is then:

W=p_2*v2-p_1*v1/n-1

W=-109,12 kJ/kg

The heat transfer Q can be calculated from the energy balance equation. For the calculation, we will need the calculated work W and the change in internal energy ΔU.

Q=W+ΔU

Q=-76,34 kJ/kg

An A-26C aircraft has 2 piston engines that drive propellers. Climbs at a flight path angle of 10 degrees. The aircraft weighs 32,000 pounds (142,343 Newtons). For a sustained climb, how much weight must EACH engine overcome in addition to the drag of the airplane?

Respondent:

320 pounds

(Video) Compression Ratio - Explained

Explanation:

Weight = T–D / % slope x 100

Where T = push and D = pull

In case of engine failure, thrust will be from 2 engine piston ie 32,000 x 2 = 64,000

Peso = (64,000-)/2x 100

Weight = 320 kg

In a balanced three-phase Y-Y circuit, 120 10 Van    V rms. The load impedance per phase is 20 15 ZZ j L Y    . Determine the load voltages and line currents. Assume a positive sequence for the three-phase circuit.

Information provided:

Balanced three-phase Y-Y circuit

Phase voltage = Van = 120 < 10° V

Load resistance = Zy = 20 +j15 Ω = 25 < 36.86° Ω

Required Information:

Load voltages = Vab, Vbc, Vca = ?

Line currents = Ia, Ib, Ic = ?

Respondent:

Vab = 208 < 40°

Vbc = 208 < -80°

Vca = 208 < 160°

Ia = 4.8 < -26.86°

Ib = 4,8 < -146,86°

Ic = 4,8 < 93,14°

Explanation:

As it is a balanced three-phase system, all phases are of equal magnitude and 120° phase shift

Van = 120 < 10° V

Vbn = 120 < -110° V

Vcn = 120 < 130° V

In a Y-connected system, the phase voltage and line voltage are related as

Vab = (Exists)

If pure oxygen is fed in excess of 25%, what would be the fractional conversion of methane so that the final concentration of CO2 in the outlet stream, in mole percent, is 10%?

Answer: The fractional conversion of methane is 12.5%

Explanation: The reaction represents the combustion of methane to produce CO2 and steam.

CH4 +2O2_CO2 + 2H2O

By gay lussac law of proportionality

1 mol of CH4 requires 2 mol of oxygen to produce 1 mol of CO2 and 2 mol of H2O

Therefore, from the mixing ratio, 25% O2 will produce 25 × 1/2% CH4.

While 12.5% ​​CO2 and 25% steam are also produced, so essentially 2.5% CO2 was lost in the reaction.

Molybdenum (Mo) has a BCC crystal structure, an atomic radius of 0.1363 nm, and an atomic weight of 95.94 g/mol. Calculate and compare your theoretical density to the experimental value found on the cover of the book.

The density of the molybdenum crystal structure is 10.22 g/cm³.

What is density?

Density can be defined as a type of physical property that is significantly concerned with describing the space occupied by an object or substance relative to the amount of matter in that object or substance.

In a simpler sense, it is characterized as the measure of quantity or mass per unit volume in a given substance.

According to this question,

The atomic radius of molybdenum is = 0.1363 nm.

The atomic weight of molybdenum is = 95.94 g/mol.

The formula for calculating the density of the BCC crystal structure is as follows:

• Density ρ= (nA *Mo)/(Vc*Na). ---------------(1)

For BCC, n = 2 atoms/unit cell and realizing that Vc = a ³

a = 4R/√3, Vc =(4R/√3)³

Avagadro number, Na = 6.022*10^23 atoms/mol.

∴ Putting the value of Vc and Na into equation 1,

ρ = (n*A Mo)/((4R/√3)³ *Na)

Vc =(4R/√3)³ = (4*0,1363*10-7 cm)³ /(√3)³

ρ =10,22 g/cm³.

Therefore, the density of the molybdenum crystal structure is 10.22 g/cm³.

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A pipeline carrying 0.50 MGD of 35,000 mg/L saline solution (NaCl) crosses a stream. Stream flow is 2.80 MGD. If the salt concentration in the stream is 175 mg/L, what is the salt concentration in the stream after the pipeline discharge has completely mixed with the stream water?'

Respondent:

water and a aaaaaaaaaaa

What is the atomic percentage composition of an alloy containing 44.5 lbmof Ag, 83.7 lbmof Au, and 5.3 lbmof Cu? What is the percentage by weight recommendation?

Respondent:

rr

Explanation:

(Video) Thermodynamic Cycles - Diesel Cycle (Part 3 of 4)

## FAQs

### Why is the thermal efficiency of the auto cycle higher than diesel engine? ›

The reason for this is that the Otto cycle has a higher maximum temperature and lower heat rejection than the Diesel cycle. - Maximum Temperature: The maximum temperature is the highest temperature reached during combustion.

Why is the thermal efficiency of the auto cycle higher than diesel engine What is the reason for increasing use of Diesel cycle instead of Otto cycle? ›

The simple answer is ,In the otto the energy available is fully used to raise the pressure in the cylinder. Higher the pressure implies larger work done. But in diesel cycle, Part of the energy is added only during the expansion, So it does not contribute to the work. Hence Otto cycle is more efficient.

Is the thermal efficiency of a diesel engine higher than the gasoline engine? ›

Diesel engines are more efficient than gasoline engines for two reasons: (i) higher cylinder pressures and corresponding higher temperatures lead to improved thermal efficiency for the diesel engine; (ii) the air throttling required to control the gasoline engine power output reduces engine efficiency and is not used ...

How does the thermal efficiency of a diesel engine increase? ›

While petrol engines usually have higher peak performance and power output, the thermal efficiency of a diesel engine is about 15 to 25% greater than that of a petrol engine. While the maximum theoretical efficiency of a diesel engine is about 70%, their usual efficiency is between 30 and 50%.

What is the main difference between an auto cycle & a diesel cycle? ›

The explosion process in a diesel engine takes place at a steady pressure. In the Otto cycle, both intake and exhaust valves move up and down, while in the Diesel cycle, only one valve moves up and one moves down. The Otto cycle and diesel cycle are two main types of the cycle used for engines.

Does the diesel cycle have a higher thermal efficiency than the Otto cycle? ›

The main difference between Otto cycle and Diesel cycle is how the heat is supplied to initiate combustion. However, in practice, a compression ratio of 20 can be achieved in a Diesel engine. Therefore, the Diesel cycle efficiency rises up to 64.7%.

Which cycle has the greater thermal efficiency? ›

The Carnot cycle, due to its fully reversible nature, represents the highest cycle efficiency possible for the two temperature limits of TH and TL; where TH represents both the heat source temperature and the temperature of the working fluid, and TL is both the working fluid temperature and the temperature of the heat ...

Do diesel engines have more thermal efficiency and less fuel consumption? ›

Diesel is more combustible than petrol, therefore less fuel is required to generate the same amount of power. Secondly, petrol doesn't undergo complete combustion and hence there is a small wastage of fuel. This is why diesel engines are more efficient than petrol engines.

Which engine has better thermal efficiency? ›

The Stirling engine has the highest theoretical efficiency of any thermal engine but it has a low output power to weight ratio, therefore Stirling engines of practical output tend to be large.

Which type of engine has higher thermal efficiency Why? ›

Still, that means the thermal efficiency of a diesel engine is about 25% greater than that of a gasoline engine. According to Popular Mechanics, the reason diesel engines have a higher thermal efficiency than gasoline engines is that of two factors: compression ratios and lean-burn combustion.

### Why are diesel engines more powerful than gasoline engines? ›

Petrol vs Diesel: Power Production

As a consequence of a higher compression ratio (longer stroke and turbocharger), diesel engines produce more torque which means you get more acceleration off the line.

What is the difference between fuel efficiency and thermal efficiency? ›

Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work.

How does the thermal efficiency of a diesel engine compare to a steam engine? ›

​Firstly the diesel engine has an impressively high thermal efficiency - with modern diesel engines achieving 45% efficiency compared to a steam engines 10% giving them to achieve greater distances between refuelling stops.

What increases thermal efficiency? ›

The efficiency of a thermal power plant can be improved by either energy conservation within the system or expansion of differences between initial steam parameters and final steam parameters.

How does it affect the thermal efficiency of a diesel cycle? ›

From the above equation, it is observed that the thermal efficiency of the diesel engine can be increased by increasing the compression ratio r, by decreasing the cut - off ratio rc, or by using gas with a large value of γ.

What's the difference between diesel and auto diesel? ›

Automobile diesel is the same as truck diesel, but the pump nozzles are not as big. And, sometimes the “automobile diesel” is priced higher than truck diesel. But, remember – to use the “truck diesel” you may need a tax-exempt permit.

What's the difference between diesel and auto? ›

Diesel mechanics work with heavy vehicles, including buses and trucks, while auto mechanics work with light vehicles, such as cars and motorcycles. Each mechanic will carry out a wide range of repair work, specialised services and maintenance checks on the specific vehicles.

What is the difference between auto and diesel engine? ›

The main difference between the petrol engine and diesel engine is that in a petrol engine, fuel and air both are compressed with a spark, while in a diesel engine, only air is compressed, and fuel is injected in compressed air.

Which engine cycle is more efficient? ›

The cycle which has the least heat rejected will have the highest efficiency. Thus, the Otto cycle is the most efficient and the Diesel cycle is the least efficient of the three cycles.

Why is the ideal Diesel cycle more efficient than the Otto cycle? ›

The most significant difference between the ideal Otto cycle and the ideal Diesel cycle is the method of igniting the fuel-air mixture. 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.

### How does the efficiency of an Otto engine compared to that of a diesel engine for the same compression ratio? ›

For the given compression , the area of P-V diagram of Otto cycle is greater than diesel cycle . Which means Otto cycle gives more work than diesel cycle for same compression i.e. the air standard efficiency of an Otto cycle is more than a diesel cycle for given compression .

Which engine typically has a higher practical efficiency an engine operating on a Diesel cycle or one operating on an Otto cycle? ›

Real diesel engines are of course considered to be more efficient that Otto cycle engines; one reason being that diesel engines typically operate at higher compression ratio and the expansion ratio from even the later stages of heat release can still be considerably higher than that of most real Otto cycle engines.

What is the difference between diesel and diesel efficient fuel? ›

Synergy Diesel Efficient™ is pre-additized to help you go up to 2% further without hassle, as compared to diesel without detergent additive. Not only does it help you cut costs on your biggest expense - fuel, but helps provide a cleaner engine, better fuel economy, and helps keep your moneymaker on the road.

Do diesel engines produce more heat? ›

Because diesel engines have higher compression ratios, they generate more heat. Because diesel engines generate more heat than other combustion engines, they have higher thermal efficiencies.

What is the thermal efficiency of diesel engines on weak? ›

The thermal efficiency of diesel engines on weak mixtures is higher. Compression-ignition engines are more fuel efficient (upto 30%) than their gasoline counterparts. Diesel has more long chain hydrocarbons, which is 15 percent more energy dense than gasoline. Weak mixture gets complete combustion.

What are the factors affecting thermal efficiency of engine? ›

The two factors of thermal efficiency are: Input heat energy. Output heat energy.

What fuel has the highest heat efficiency? ›

Among the given options, hydrogen is the fuel with highest calorific value of 150000 kJ/kg. Therefore, hydrogen is considered as the most efficient fuel.

Which engine has the highest efficiency? ›

The electric engine is most efficient. Electric motors are very efficient at converting electricity into work. Physicists throw around abstract numbers like 90%, whereas when discussing combustion engines, they use numbers less than 40%.

Why are fuel cells more efficient than heat engines? ›

Fuel cells are more efficient than combustion engines as they operate at a higher thermodynamic efficiency. Combustion engines must first convert their fuel into heat, then into mechanical energy, and finally into electricity. Fuel cells skip those intermediary steps.

Which engine exists as the engine with the highest thermal efficiency either with the internal or external combustion engine? ›

Diesel engine exists as the engine with the highest thermal efficiency either with the internal or external combustion engine.

### Which of the two types of engines is more efficient? ›

There are two main types of piston engine: the spark-ignition engine and the diesel engine. The diesel engine is more efficient but it also generates more pollution.

What is the thermal efficiency of gas turbine as compared to diesel plant? ›

Assertion (A): The thermal efficiency of gas turbine plants is higher compared todiesel plants. Reason (R): The mechanical efficiency of gas turbines is higher compared to dieselengines. Correct answer is option 'D'.

What is the thermal efficiency of a gas turbine as compared to diesel engine plant? ›

Gas Turbine Generator:

The thermal efficiency at 20%–26% is, however, generally lower than comparable steam turbine plant and much lower than equivalent diesel plant.

What is the thermal efficiency of gasoline? ›

The thermal efficiency must be between 0% and 100% when expressed as a percentage. Due to factors including friction, heat loss, etc., thermal efficiencies typically are much less than 100%. A typical automotive gasoline ICE operates at around 25%.

What is the thermal efficiency of petrol engine as compared to diesel engine is at same compression ratio? ›

Explanation: The compression ratio in I.C. engine is directly proportional to the thermal efficiency, so as it increases, then its thermal efficiency will increase. Explanation: The thermal efficiency of petrol and gas engines is about 30% and the thermal efficiency of diesel engines is about 70%.

What is the thermal efficiency of a petrol engine in comparison with diesel engine for same compression ratio? ›

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.

How much greater is the thermal efficiency of diesel engine whereas that of petrol engine varies from per cent? ›

The thermal efficiency of diesel engine varies from 32 to 38 per cent whereas that of petrol engine varies from 25 to 32 per cent. In modern days, almost all the tractors and power tillers are operated by diesel engines.

What makes thermal energy greater? ›

When the temperature of an object increases, the average kinetic energy of its particles increases. When the average kinetic energy of its particles increases, the object's thermal energy increases. Therefore, the thermal energy of an object increases as its temperature increases.

What is the thermal efficiency of a diesel engine varies between? ›

Diesel engine:

While petrol engines usually have higher peak performance and power output, the thermal efficiency of a diesel engine is about 15 to 25% greater than that of a petrol engine. While the maximum theoretical efficiency of a diesel engine is about 70%, their usual efficiency is between 30 and 50%.

How can I increase the efficiency of my diesel engine? ›

Behavioral Ways to Increase Diesel Engine Fuel Mileage
1. Avoid Idling. ...
2. Use Synthetic Oil. ...
3. Accelerate Evenly. ...
4. Use the Cruise. ...
5. Lower Your Highway Speed. ...

### Why is thermal efficiency high in diesel engines? ›

Because diesel has a higher compression resistance — because it is denser than light distillate fuels — engineers can design and develop diesel engines with higher compression ratios than gasoline engines. The higher the compression ratio of an engine, the greater the thermal efficiency.

Is thermal efficiency higher in a diesel engine than in a gasoline engine? ›

A diesel engine is about 20% more thermal efficient than a gas engine. This directly relates to a 20% increase in fuel economy. Diesel engines are used in a wide variety of equipment and vehicles, anywhere from medium duty trucks to overseas cruise ships and power generators.

Which cycle has the highest thermal efficiency? ›

The Carnot cycle, due to its fully reversible nature, represents the highest cycle efficiency possible for the two temperature limits of TH and TL; where TH represents both the heat source temperature and the temperature of the working fluid, and TL is both the working fluid temperature and the temperature of the heat ...

How does it affect the thermal efficiency of a Diesel cycle? ›

From the above equation, it is observed that the thermal efficiency of the diesel engine can be increased by increasing the compression ratio r, by decreasing the cut - off ratio rc, or by using gas with a large value of γ.

Which engine has the highest thermal efficiency? ›

The Stirling engine has the highest theoretical efficiency of any thermal engine but it has a low output power to weight ratio, therefore Stirling engines of practical output tend to be large.

How is the efficiency of thermal cycle increased? ›

By increasing the temperature and pressure, the Tm of the cycle increases so efficiency will increase.

What is the maximum thermal efficiency of a diesel engine? ›

What is the maximum efficiency an engine can achieve? The diesel engine has a theoretical system efficiency of between 55-60%. For reference, the best power stations operate at 50-55% efficiency, and fuel cells are also around 50%+ efficient – so diesel engines can be incredible efficient.

Why are diesel engines better than steam engines? ›

Diesels replaced steam locomotives because that's what they did - they are more efficient because they cost less money to run. This article, written by US locomotive engineer Al Krug in a series of newsgroup posts, tries to explain the power questions that show how diesels are more efficient than steam locomotives.

Is the Diesel cycle known to be the most efficient cycle? ›

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%.

What is the thermal efficiency of a car engine? ›

Most modern gasoline engines have a thermal efficiency of around 40%. That means that 40% of the energy created when its fuel is burned gets turned into motion. According to a report published Friday by Reuters, Nissan thinks it's found a way to increase that number to 50%.

### Which thermodynamic cycle engine is more efficient? ›

Classical thermodynamics indicates that the most efficient thermodynamic cycle operating between two heat reservoirs is the Carnot engine  , and a basic theorem expresses that any reversible cycle working between two constant temperature levels should have the same efficiency as a Carnot cycle .

What are some factors that affect the efficiency of automobile engines? ›

These include the chemical energy loss in emissions, heat losses from the engine and through the exhaust gas, and gas pumping and friction losses in the engine. Accordingly, the overall brake thermal efficiency of the engine is a product of the combustion, thermodynamic, gas exchange, and mechanical efficiency.

## Videos

1. A 50% More Efficient Internal Combustion Engine
(Voice of America)
2. The Diesel Cycle
(Thermofluids)
3. Lecture 12a Internal Combustion Engine Otto and Diesel Cycle
(DrKhan)
4. Mechanical Engineering Thermodynamics - Lec 16, pt 3 of 6: Ideal Diesel Cycle
(Ron Hugo)
5. OTTO CYCLE | DIESEL CYCLE | PROBLEM
(Kim Benzon)
6. SHELL OIL CO. "THE DIESEL STORY" RUDOLF DIESEL & DEVELOPMENT OF DIESEL ENGINE 48124
(PeriscopeFilm)
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