# Can the thermal efficiency of heat engine be 100 %? Give reason for your answer?

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It is impossible for heat engines to achieve 100% thermal efficiency () according to the Second law of thermodynamics. This is impossible because some waste heat is always produced produced in a heat engine, shown in Figure 1 by the term.

## What do you understand thermal efficiency of heat engine can this be 100% give reasons?

The efficiency of a heat engine can be 100% only if all the heat energy gets converted into work (or mechanical energy). … Since heat energy can never be transformed completely into mechanical energy, so the efficiency of a heat engine can never be 100 per cent.

## Can efficiency of any heat engine be hundred percent right answer with reason?

A heat engine is considered to be 100% efficient if only all the heat is converted into useful work or mechanical energy. Since heat engines cannot convert all the heat energy into mechanical energy, their efficiency can never be 100%. … The modern heat engines built with further improved designs have 40% efficiency.

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## Can Carnot efficiency be 100%?

It can be 100℅ only if the sink temperature is zero or the source temperature is infinite (very large value). Carnot is an ideal cycle is provides benchmark to compare efficiency of other cycles. Carnot efficiency is the maximum efficiency that can be achieved in a cycle.

## Under what conditions would an ideal heat engine be 100% efficient?

For engine to be 100% efficient, all input energy would need to be converted into useful output energy. The output of a 100% efficient engine would be all work & no heat, no pollution, no emissions, no noise or vibration.

## Can 100% efficiency be achieved?

It is impossible for heat engines to achieve 100% thermal efficiency () according to the Second law of thermodynamics. This is impossible because some waste heat is always produced produced in a heat engine, shown in Figure 1 by the term.

## What are the factors to thermal efficiency?

In theory, the factors that affect thermal efficiency (the performance of an engine or the work it has done in relation to the value of heat supplied to it) are the heat input and the heat output. Additionally, temperature variations also come in play, the amount and the rate of losing or gaining heat.

## Why 100% efficiency is not possible?

Explanation: No machine is free from the effects of gravity, and even with wonderful lubrication, friction always exists. The energy a machine produces is always less than the energy put into it (energy input). … That is why 100% efficiency in machines shall not be possible.

## What is the most efficient heat engine?

The most efficient heat engine cycle is the Carnot cycle, consisting of two isothermal processes and two adiabatic processes. The Carnot cycle can be thought of as the most efficient heat engine cycle allowed by physical laws.

## What is the formula for thermal efficiency?

The thermal efficiency, ηth, represents the fraction of heat, QH, that is converted to work. The air-standard Otto cycle thermal efficiency is a function of compression ratio and κ = cp/cv. The thermal efficiency, ηth, represents the fraction of heat, QH, that is converted to work.

## What is the Carnot efficiency?

Carnot efficiency is the maximum efficiency that a heat engine may have operating between the two temperatures (Figure 2-7). … Carnot process efficiency. The Carnot efficiency has little practical value. It is a maximum theoretical efficiency of a hypothetical engine.

## How do we calculate efficiency?

The work efficiency formula is efficiency = output / input, and you can multiply the result by 100 to get work efficiency as a percentage. This is used across different methods of measuring energy and work, whether it’s energy production or machine efficiency.

## What is ideal efficiency?

From the first law of thermodynamics, the energy output cannot exceed the input, and by the second law of thermodynamics it cannot be equal in a non-ideal process, so. When expressed as a percentage, the thermal efficiency must be between 0% and 100%.

## How can you increase the efficiency of a heat engine?

Therefore, the efficiency of the heat engine can be increased by decreasing the temperature of the cold sink or increasing the temperature of the hot source.

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## Is Carnot engine reversible?

The Carnot heat-engine cycle described is a totally reversible cycle. That is all the processes that compose it can be reversed, in which case it becomes the Carnot refrigeration cycle.

## Is Carnot cycle reversible?

The Carnot cycle consists of the following four processes: A reversible isothermal gas expansion process. In this process, the ideal gas in the system absorbs qin amount heat from a heat source at a high temperature Thigh, expands and does work on surroundings.

T-S Diagram.

Process ΔT ΔS
Full Cycle 