Table of Contents
- 1 Why do you think it is impossible to produce a 100\% efficient engine?
- 2 What engine violates the second law of thermodynamics?
- 3 Is irreversible engines have maximum efficiency?
- 4 How does the second law of thermodynamics apply to heat engines?
- 5 How does a Carnot engine work?
- 6 What is the difference between input energy and output energy?
Why do you think it is impossible to produce a 100\% efficient engine?
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.
Is it possible to construct a heat engine that does not transfer energy to its surroundings?
Because the hot reservoir is heated externally, which is energy intensive, it is important that the work is done as efficiently as possible. In fact, we would like W to equal Qh, and for there to be no heat transfer to the environment (Qc=0). Unfortunately, this is impossible.
What engine violates the second law of thermodynamics?
If a heat engine is purported to have a thermal efficiency greater than the Carnot efficiency, the heat engine is in violation of the second law of thermodynamics. The first and second laws of thermodynamics are the quintessential governing principles on which all energy processes are based.
Can a Carnot heat engine attain 100\% efficiency?
In order to achieve 100\% efficiency (η=1), Q2 must be equal to 0 which means that all the heat form the source is converted to work. Hence negative temperature of absolute scale is impossible and we cannot reach absolute 0 temperature. …
Is irreversible engines have maximum efficiency?
All the reversible and irreversible engines have the same efficiency. Irreversible engines have maximum efficiency. All engines are designed as reversible in order to obtain maximum efficiency.
Is it possible to create an engine that does not produce thermal exhaust?
It is not possible to construct a heat engine which is free from thermal pollution.
How does the second law of thermodynamics apply to heat engines?
15.3 Introduction to the Second Law of Thermodynamics: Heat Engines and Their Efficiency. The second law of thermodynamics deals with the direction taken by spontaneous processes. A cold object in contact with a hot one never gets colder, transferring heat to the hot object and making it hotter.
How heat engine is an example of second law of thermodynamics?
(a) Heat transfer occurs spontaneously from a hot object to a cold one, consistent with the second law of thermodynamics. (b) A heat engine, represented here by a circle, uses part of the heat transfer to do work. The hot and cold objects are called the hot and cold reservoirs.
How does a Carnot engine work?
A Carnot engine takes in heat from a reservoir at 720°C and releases heat to a lower-temperature reservoir at 180°C. What is its efficiency? The efficiency of the Carnot engine is
What is the work done by the engine on the environment?
The engine is assumed to do work, δW0, on the environment. In addition, a second device that also operates in a cycle absorbs heat, δQ, at temperature, T, that is rejected from the reversible engine. The work done by the latter equals δW, and is equal to the heat transfer δQ. Figure 2.33. System for Clausius inequality explanation
What is the difference between input energy and output energy?
Input, Output, and Efficiency Input refers to the amount of energy put into a device, and output refers to the amount of energy that comes out. A device may change the type of energy but not the amount. For example, a light bulb’s input energy is the form of
What is the relationship between temperature and heat input in engines?
Consider now a system that encloses both engines, and operates in a cycle. The temperature, T, changes from cycle to cycle, and so does the work, δW, that is done on the environment by the cyclic engine. Over a cycle, this work, δW, is exactly equal to the heat input, δQ, to the cyclic engine, i.e.