Thermodynamics and Heat Transfer

 

Thermodynamics and Heat Transfer:-

Both thermodynamics and warmth transfer is a part of thermal engineering, each with its own meaning and importance. Both affect heat and energy, so what is the real difference between the 2 subjects? that's, thermodynamics and warmth transfer

"Thermodynamics" deals with the quantity of energy within the sort of heat or work during the method and considers only the ultimate state in equilibrium. No information is provided about the time it takes to succeed in the ultimate state of equilibrium. In the meantime,

Since "heat transfer" deals with the speed of energy transfer, can we all know how long the warmth transfer will occur? Heat transfer deals with time & non-equilibrium working. Heat can only be transferred if there's a gradient within the body and it exhibits a non-equilibrium phenomenon.

In short, thermodynamics shows the "reason" for a process to occur, and warmth transfer shows the "way" for a process to occur when heat transfer may be a concern.

To support these arguments, thermodynamics uses the subsequent law:

• Zero law of thermodynamics

• First law of thermodynamics

• Second law of thermodynamics

• Third law of thermodynamics

On the opposite hand, heat transfer

• Fourier's law (heat conduction)

• Newton's law of motion of cooling (heat convection)

• Planck's law (heat radiation)

• Stefan-Boltzmann's law (heat radiation)

• Vienna's Law (Heat Radiation)

• Kirchhoff's Law (heat radiation)

• Lambert's Law (heat radiation)

When covering thermodynamics, it is a phenomenon to study the spontaneity of thermodynamic processes, process parameters at specific state points, etc., but heat transfer is a phenomenon that studies many other parameters such as flow behavior, material properties, temperature gradients, etc. Handles.

In thermodynamics, reaction time plays no role, but heat transfer helps determine the exact time and quantity-based parameters involved in the process. How heat flows from the body to body, where uniformity is lost, and so on.

Looking at the laws related to thermodynamic calculations, we can list them as follows:

• Zero Law of Thermodynamics (Defines Temperature)

• First law of thermodynamics (defining internal energy)

• Second law of thermodynamics (defining entropy)

• Third law of thermodynamics (limits the minimum achievable temperature)

Observe the process parameters that are important in this type of process. Heat transfer, on the other hand, has the following rules regarding the calculation of process variables:

• Fourier's law (heat conduction)

• Newton's law of cooling (heat convection)

• Planck's law (heat radiation)

• Stefan-Boltzmann's law (heat radiation)

• Vienna's Law (Heat Radiation)

• Kirchhoff's Law (heat radiation)

• Lambert's Law (heat radiation)

Heat transfer is slightly broader than thermodynamics and is a bit more specific throughout the process. Obtain or analyze variables related to actual heat transfer issues, taking into account material type, shape, fluid flow, temperature gradients, and many other parameters.

However, heat transfer does not take into account the calculation of process endpoints, but there is no mistake if you formalize the following equation:

Heat transfer = thermodynamics + materials science + fluid mechanics

However, unlike explaining the 100% depth of these topics related to the calculation of actual heat transfer problems, some of all these subjects are concerned with the calculation of heat transfer problems. The segment has something to do with it.

In conclusion, we can say that:

Thermodynamics is a process descriptor that shows the total amount of heat, energy, work, dissipation, etc., and does not include individual states (unless properly defined in the process parameters), but heat transfer is non-equilibrium. It is a study of thermodynamics. Equilibrium and the entire process at various steps. Look for uniformity, material properties, strain, thermal stress, etc. Heat transfer is actually a study of the transfer coefficient of these physical variables such as energy and material properties.

Both topics are about thermal energy, but each has its own differences, so let's pick a few that you remember at this point.

Thermodynamics mainly deals with the equilibrium process. Thermodynamics allows you to know how much heat needs to be added or removed in your system to move from one equilibrium to another. As I said, the amount of heat transfer of any system going through any process can be calculated using only thermodynamic analysis. The reason is that thermodynamics is related to the amount of heat transfer as the system goes through a particular process, but does not indicate how long the process is. Therefore, the thermodynamic analysis here simply shows how much heat needs to be transferred to achieve a particular state change in order to satisfy the law of conservation of energy.

One real example. Suppose you heat 5 kg of water to 30-100 ° C. Thermodynamics gives you the amount of heat you need. Let's say you need 1470kJ. Well, can you wait a day to heat that amount of water? Alternatively, you can wait 5 hours and heat that amount of water to 100 ° C. Or, if you don't have a job, you can think of it that way. However, if you are a busy person and want to get the heat out within a few minutes, you need to get the help of heat transfer here to fix the time. Therefore, the speed is fixed by the knowledge of heat transfer. Only quantity is fixed by knowledge of thermodynamics. Therefore, if you want to heat within 15 minutes, you have to supply heat to the water at a rate of 1.63kW. If you want to heat within 30 minutes, you can supply heat at a rate of 0.81kW. This is where heat transfer makes a difference in thermodynamics.

Another example. When you reach the real world, most applications are interested in heat transfer coefficient. The best example is a thermos. The amount of heat transferred from a thermos when the hot coffee cools from 90 ° C to 80 ° C can be determined only by thermodynamic analysis, but the general designer of a thermos mainly says until the hot coffee inside is filled. I'm interested in time. Cooled to 80 ° C, thermodynamic analysis cannot answer the question. Determining the heat transfer coefficient to and from the system is handled by heat transfer to meet a certain amount.