What is the efficiency of a Carnot engine?
The Carnot Efficiency is the theoretical maximum efficiency one can get when the heat engine is operating between two temperatures: The temperature at which the high temperature reservoir operates ( THot ). The temperature at which the low temperature reservoir operates ( TCold ).
What are the corollaries of Carnot theorem?
Corollary 1 of Carnot’s Theorem: The first Corollary of Carnot’s theorem can be stated as follows: All reversible heat engines operating between the same two heat reservoirs must have the same efficiency.
What was the original unit for measuring heat?
BTU
What are the two statements known as the Carnot principles?
Carnot principles can be expressed as the following two statements: 1. The efficiencies of all reversible heat engines operating between a constant temperature source (TH) and a constant temperature sink (TL) are the same. They only depend on the high temperature TH=const and the low temperature TL=const.
What is COP in mechanical engineering?
COP stands for Coefficient Of Performance and indicates the efficiency of heating and cooling machines. The COP is defined by the ratio heat dissipation and electrical power intake.
What is Carnot ideal engine?
Carnot engine is a theoretical thermodynamic cycle proposed by Leonard Carnot. It gives the estimate of the maximum possible efficiency that a heat engine during the conversion process of heat into work and conversely, working between two reservoirs, can possess.
Why is Carnot engine ideal?
The Carnot cycle can be thought of as the most efficient heat engine cycle allowed by physical laws. When the second law of thermodynamics states that not all the supplied heat in a heat engine can be used to do work, the Carnot efficiency sets the limiting value on the fraction of the heat which can be so used.
Is Carnot engine real?
Any engine using the Carnot cycle, which uses only reversible processes (adiabatic and isothermal), is known as a Carnot engine. Any engine that uses the Carnot cycle enjoys the maximum theoretical efficiency.
Why is efficiency of heat engine less than 1?
Answer. Because according to Second law of thermodynamics ( KELVIN- PLANK STATEMENT ) some part of input energy always goes into the sink i.e low temperature reservoir and gets wasted. ….. The efficiency of a real engine is always less than that of a Carnot engine.
What are the essential requirements of heat engine?
1. They receive heat from a high-temperature source (solar energy, furnace etc.). 2. They convert part of this heat to work.
What are two essential features of Carnot’s ideal heat engine?
Answer. 1-It should have a source of infinite thermal capacity. 2-It should have a sink of infinite thermal capacity.
What are the advantages and disadvantages of a heat engine?
The main disadvantage of a heat engine is the limitation of efficiency. Heat engine has the advantage that any forms of energy can be easily converted to heat energy by the process of combustion, absorption of light, friction or resistance.
How can we increase the efficiency of 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.
Why can a machine never have 100% efficiency?
A machine cannot be 100 percent efficient because output of a machine is always less than input. A certain amount of work done on a machine is lost to overcome friction and to lift some moving parts of the machine.
How do you increase Carnot efficiency?
The efficiency of the carnot engine can be increased by either increasing the sink temperature or by decreasing the reservoir temperature.
What is the formula of efficiency of Carnot engine?
It is well known that the Carnot cycle efficiency ( η thermal = 1 − T L T H ) is maximized with the highest possible heat source temperature TH and the lowest possible heat sink temperature TL.
What is the formula for thermal efficiency?
The thermal efficiency is a dimensionless unit. If you take formulas in thermodynamics, you can get that η= 1- (T COLD/THOT). TCOLD usually represents the ambient temperature where the engine is located. This may just be the temperature outside in whatever environment the engine is at.
What is the unit of thermal efficiency?
The heating value of a fuel is the amount of heat released during an exothermic reaction (e.g., combustion) and is a characteristic of each substance. It is measured in units of energy per unit of the substance, usually mass, such as: kJ/kg, J/mol.
What are the factors of thermal efficiency?
The thermal efficiency of a heat engine is expressed as a product of the Carnot efficiency, the external irreversibility factor and the internal irreversibility factor, by which the three factors that affect the thermal efficiency can be clearly distinguished, and the influences of the external and internal …
Which engine has more thermal efficiency?
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 are the two factors affecting the thermal efficiency of cycle?
What is thermal efficiency of gas turbine?
When the gas turbine is used solely for shaft power, its thermal efficiency is about 30%. However, it may be cheaper to buy electricity than to generate it. Therefore, many engines are used in CHP (Combined Heat and Power) configurations that can be small enough to be integrated into portable container configurations.
What is thermal efficiency of petrol engine?
Gasoline (petrol) engines Modern gasoline engines have a maximum thermal efficiency of more than 50%, but road legal cars are only about 20% to 35% when used to power a car.