Relative Efficiency Calculator

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Engine Performance Parameters

Air-Standard Cycles

Design of IC Engine Components

Fuel Injection in IC Engine

Fundamentals of IC Engine

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For 4 Stroke Engine

✖Indicated Thermal Efficiency is given by the ratio of indicated power generated by the engine to the power generated by the combustion of the fuel.ⓘ Indicated Thermal Efficiency [IDE]			+10% -10%
✖Air Standard Efficiency (in %) is the efficiency of the engine using air as the working medium. This efficiency is often called ideal efficiency.ⓘ Air Standard Efficiency [η_air]			+10% -10%

✖The Relative Efficiency of an I.C. engine is the ratio of indicated thermal efficiency to the thermal efficiency of a theoretically reversible cycle.ⓘ Relative Efficiency [η_rel]

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Formula

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Relative Efficiency

Formula

`"η"_{"rel"} = ("IDE"/"η"_{"air"})*100`

Example

`"84"=("42"/"50")*100`

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Relative Efficiency Solution

STEP 0: Pre-Calculation Summary

Formula Used

Relative Efficiency = (Indicated Thermal Efficiency/Air Standard Efficiency)*100
η_rel = (IDE/η_air)*100
This formula uses 3 Variables

Variables Used

Relative Efficiency - The Relative Efficiency of an I.C. engine is the ratio of indicated thermal efficiency to the thermal efficiency of a theoretically reversible cycle.
Indicated Thermal Efficiency - Indicated Thermal Efficiency is given by the ratio of indicated power generated by the engine to the power generated by the combustion of the fuel.
Air Standard Efficiency - Air Standard Efficiency (in %) is the efficiency of the engine using air as the working medium. This efficiency is often called ideal efficiency.

STEP 1: Convert Input(s) to Base Unit

Indicated Thermal Efficiency: 42 --> No Conversion Required
Air Standard Efficiency: 50 --> No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

η_rel = (IDE/η_air)*100 --> (42/50)*100

Evaluating ... ...

η_rel = 84

STEP 3: Convert Result to Output's Unit

84 --> No Conversion Required

FINAL ANSWER

84 <-- Relative Efficiency

(Calculation completed in 00.004 seconds)

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Credits

Created by Aditya Prakash Gautam

Indian Institute of Technology (IIT (ISM) ), Dhanbad, Jharkhand

Aditya Prakash Gautam has created this Calculator and 25+ more calculators!

Verified by Anshika Arya

National Institute Of Technology (NIT), Hamirpur

Anshika Arya has verified this Calculator and 2500+ more calculators!

< 13 Engine Performance Parameters Calculators

Inlet-Valve Mach Index

Go Mach Index = ((Cylinder Diameter/Inlet Valve Diameter)^2)*((Mean Piston Speed)/(Flow Coefficient*Sonic Velocity))

Brake Power given Mean Effective Pressure

Go Brake Power = (Brake Mean Effective Pressure*Stroke Length*Area of Cross Section*(Engine Speed))

Indicated Thermal Efficiency given Indicated Power

Go Indicated Thermal Efficiency = ((Indicated Power)/(Mass of fuel supplied per second*Calorific value of fuel))*100

Brake Thermal Efficiency given Brake Power

Go Brake Thermal Efficiency = (Brake Power/(Mass of fuel supplied per second*Calorific value of fuel))*100

Indicated specific fuel consumption

Go Indicated Specific Fuel Consumption = Fuel Consumption in IC engine/Indicated Power

Indicated Thermal Efficiency given Relative Efficiency

Go Indicated Thermal Efficiency = (Relative Efficiency*Air Standard Efficiency)/100

Relative Efficiency

Go Relative Efficiency = (Indicated Thermal Efficiency/Air Standard Efficiency)*100

Brake specific fuel consumption

Go Brake Specific Fuel Consumption = Fuel Consumption in IC engine/Brake Power

Indicated Power given Mechanical Efficiency

Go Indicated Power = Brake Power/(Mechanical Efficiency/100)

Brake Power given Mechanical Efficiency

Go Brake Power = (Mechanical Efficiency/100)*Indicated Power

Mechanical Efficiency of IC engine

Go Mechanical Efficiency = (Brake Power/Indicated Power)*100

Specific Power Output

Go Specific Power Output = Brake Power/Area of Cross Section

Friction Power

Go Friction Power = Indicated Power-Brake Power

Relative Efficiency Formula

Relative Efficiency = (Indicated Thermal Efficiency/Air Standard Efficiency)*100
η_rel = (IDE/η_air)*100

What is relative efficiency of an IC engine ?

Relative efficiency or 'Efficiency Ratio' is the ratio of indicated thermal efficiency and the air standard efficiency of an IC engine or the ratio of the actual efficiency obtained from an engine to the theoretical efficiency of the engine cycle.

How to Calculate Relative Efficiency?

Relative Efficiency calculator uses Relative Efficiency = (Indicated Thermal Efficiency/Air Standard Efficiency)*100 to calculate the Relative Efficiency, The Relative Efficiency formula is defined as the ratio of indicated thermal efficiency and the air standard efficiency of an IC engine. Relative Efficiency is denoted by η_rel symbol.

How to calculate Relative Efficiency using this online calculator? To use this online calculator for Relative Efficiency, enter Indicated Thermal Efficiency (IDE) & Air Standard Efficiency (η_air) and hit the calculate button. Here is how the Relative Efficiency calculation can be explained with given input values -> 84 = (42/50)*100.

FAQ

What is Relative Efficiency?

The Relative Efficiency formula is defined as the ratio of indicated thermal efficiency and the air standard efficiency of an IC engine and is represented as η_rel = (IDE/η_air)*100 or Relative Efficiency = (Indicated Thermal Efficiency/Air Standard Efficiency)*100. Indicated Thermal Efficiency is given by the ratio of indicated power generated by the engine to the power generated by the combustion of the fuel & Air Standard Efficiency (in %) is the efficiency of the engine using air as the working medium. This efficiency is often called ideal efficiency.

How to calculate Relative Efficiency?

The Relative Efficiency formula is defined as the ratio of indicated thermal efficiency and the air standard efficiency of an IC engine is calculated using Relative Efficiency = (Indicated Thermal Efficiency/Air Standard Efficiency)*100. To calculate Relative Efficiency, you need Indicated Thermal Efficiency (IDE) & Air Standard Efficiency (η_air). With our tool, you need to enter the respective value for Indicated Thermal Efficiency & Air Standard Efficiency and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

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