What are the four thermodynamic process?
What are the different types of thermodynamic processes?
What is thermodynamic process Class 11?
A system goes through a thermodynamic process when there is some kind of energetic change within the system, usually associated with differences in volume, pressure, temperature, internal energy, or any kind of heat transfer.
Main Types of Thermodynamic Process
There are several specific types of thermodynamic processes that occur frequently enough (and in practical situations) and are widely covered in thermodynamic studies. Each has a unique feature that defines itself, and this is useful in analyzing the energy and job changes associated with the process.
• Adiabatic process: A process that does not transfer heat to or from the system.
• Isochoric process: It is a process with no change in volume, in this case the system does not work.
Isobaric process: a process with no change in pressure
Isothermal process: a process with no change in temperature
It is possible to have more than one process in a single process. The most obvious example would be a situation where a change in pressure and volume does not cause any change in heat transfer or temperature. Here such a process will be both isothermal and adiabatic.
The First Law of Thermodynamics
In mathematical terms, the first law of thermodynamics can be written as:
delta- U = Q – W veya Q = delta- U + W
• delta- U = change in internal energy of the system
• Q = heat transferred into or out of the system.
• W = work done by or on the system.
When analyzing one of the special thermodynamic processes described above, a very lucky result is often (though not always) obtained, one of these quantities drops to zero!
For example, there is no heat transfer in an adiabatic process Q delta: obtained in a very simple relationship between internal energy and work = 0, S – = W. Separate descriptions of these processes should be consulted for more specific details on their unique properties.
Most thermodynamic processes naturally proceed from one direction to the other. In other words, they have a preferred aspect. Heat flows from a warmer object to a cooler one. Gases expand to fill a room but will not spontaneously contract to fill a smaller space. All mechanical energy can be converted into heat, but it is almost impossible to completely convert heat into mechanical energy.
However, some systems go through a reversible process. Generally, this happens when the system is always close to thermal equilibrium, both inside the system and in any environment. In this case, infinitesimal changes in the conditions of the system can cause the process to go the other way. Therefore, a reversible process is also known as an equilibrium process.
Example 1: The two metals (A and B) are in thermal contact and thermal equilibrium. Metal A is heated in an infinitely small amount so that heat flows from it to metal B. This process can be reversed by cooling A by an infinitesimal amount, at which point the heat will begin to flow from B to A until it reaches thermal equilibrium once again.
Example 2: For example, a gas expands adiabatically and slowly in a reversible process. By increasing the pressure by an infinitesimal amount, the same gas can slowly and adiabatically return to its initial state.
It should be noted that these are somewhat idealized examples. For practical purposes, a system that is in thermal equilibrium ceases to be in thermal equilibrium when one of these changes is applied, so the process is actually not completely reversible. When this is one, a fully reversible state that is extremely close to reality can be obtained with the idealized model experimental conditions and a carefully controlled process.
Irreversible Processes and the Second Law of Thermodynamics
Of course, most processes are irreversible processes (or unstable processes). Using the friction of the brakes working in the vehicle is an irreversible process. Allowing air to be released into the room from a balloon is an irreversible process. Placing a block of ice on a hot cement walkway is an irreversible process.
In general, these irreversible processes are the result of the second law of thermodynamics, often defined as the entropy or disorder of a system. There are several ways to express the second law of thermodynamics, but it basically places a limitation on how efficient any heat transfer can be. According to the second law of thermodynamics, some heat will always be lost in the process, so it is not possible to have a completely reversible process in the real world.
Heat Engines, Heat Pumps and Other Devices
Any device that partially converts heat into work or mechanical energy is called a heat engine. A heat engine does this by transferring heat from one place to another and doing some work along the way. Using thermodynamics, it is possible to analyze the thermal efficiency of a heat engine, and this is a topic covered in most introductory physics courses. Here are some heat engines that are frequently analyzed in physics lessons:
• Internal Combustion Engine: An engine that runs on fuel such as those used in automobiles. The “Otto cycle” describes the thermodynamic process of a normal gasoline engine. “Diesel cycle” refers to Diesel engines.
• Refrigerator: A reverse heat engine takes heat from a cold place (inside the refrigerator) and transfers it to a warm place (outside the refrigerator).
• Heat Pump: A heat pump is a refrigerator-like heat engine used to heat buildings by cooling the outside air.
French engineer Sadi Carnot created a hypothetical engine in 1924, which is an idealized shape with the highest possible efficiency consistent with the second law of thermodynamics. For its efficiency, it reached the following equation:
e Carnot = ( T H – T C ) / T H
TH and TC are the temperatures of hot and cold reservoirs, respectively. High efficiency is obtained with a very large temperature difference. If the temperature difference is low, there is a low efficiency. Efficiency of 1 (100% efficiency) can only be achieved if the impossible TC = 0 (ie absolute value).