You may have heard of the Carnot cycle and how it works. But have you ever wondered why energy transfers are so efficient? In fact, this concept explains the most effective way to transfer energy. You have to move a fluid from a high temperature to a low temperature. Then, you have to spread the energy throughout the entire system. This principle can be applied to all kinds of scientific questions, from how the universe began to why time flows forward.
Carnot cycle:
The Carnot efficiency of the universe, eC, is the ratio of the total heat and entropy of a system to the total heat and entropy of its surrounding system. Carnot first proposed the concept of a “heat engine” that involved alternating adiabatic and isothermal processes. Although Carnot did not have the benefit of modern definitions of entropy, he did manage to show that the entropy of the universe could be kept constant in the theoretical cycle.
Reversible heat engine:
A reversible heat engine is one that transfers the same amount of energy from one body to another. This engine is said to be more efficient when the entropy of the environment is the same as that of the vehicle. Similarly, a reversible heat engine is said to be less efficient when the temperature of the vehicle and the temperature of the working fluid are different. This property is known as the Carnot efficiency.
Maximum possible efficiency:
The most obvious way to calculate the maximum possible carnot efficiency of the universe is to apply a multiscale model to the question of energy. For example, the Carnot engine is an example of this. It operates between two temperature extremes, which translates into work. However, fuel cells extract chemical energy much more efficiently. Electrical energy, on the other hand, is not affected by the Carnot inefficiency. For example, the Toyota Prius uses regenerative braking, which converts the KE of stopping into electricity. The stored electricity can then be used to re-accelerate the car.
Processes involved:
The Carnot efficiency of the universe can be defined as a reversible heat engine operating between two thermal reservoirs. For this equation, x is the same in both the S and Carnot engines. Hence, the equation for the latter is Q2 = Q1 + W. The inverse of Q1 is W. Thus, x=q1 + q2 = q2 + q-W.
Relationship with second law of thermodynamics:
The first law of thermodynamics states that heat flows from a cold body to a warm one without a change in the surrounding temperature. The second law states that heat cannot flow from a hot body to a cold one without some other change. The laws of thermodynamics are commonly used in engineering practice and in environmental accounting. This law explains how heat is transferred from one body to another by converting mechanical energy to thermal energy.