First Partial

Question 1

The word thermodynamics

Answer 1

From Greek: therme (heat)🔥dynamics (force)💪🏼.

Question 2

Two definitions of Thermodynamics:

Answer 2

The science of energy, it studies the interconversions of heat into work.
~Cengel and Boles

Thermodynamics is a branch of the physics that studies the energy and work associated with a system. It began in XIX with the steam engines.
~NASA Glen Research Center

Question 3

What does the thermodynamics do in general words?

Answer 3

Q (heat)👉🏻W (work)

Question 4

Fundamental Laws:

Answer 4

• Law zero: thermal equilibrium: The heat goes to the warmer object to the coldest one.
• First law of thermodynamics: energy conservation: The energy is not created or destroyed but it can be transformed.
• Second law of thermodynamics: entropy: the direction of the processes, whether the process is possible or not.

1850, Rankine, Clausius, Kelvin.

Question 5

Molecules

Answer 5

A substance consists of a large number of particles called molecules.

Question 6

Microscopic level

Answer 6

(statistical thermodynamics, kinetic theory)

The properties of the substance naturally depend on the behavior of these particles.

Question 7

Macroscopic level

Answer 7

This approach does not study the behavior of individual particles, but considera the continuum model.

Question 8

Theory of continuum.

Answer 8

The description of a substance should consider the behavior of each molecule. The equations that describe the behavior should be developed for each equation.

Question 9

What does the continuum assume?

Answer 9

That it is possible to simplify the granular description of the substance by using averages, and considering adequate control volumes.

IMAGEN CON FORMULA

Question 10

Adequate control volumes?

Answer 10

IMAGEN

Question 11

Continuum

An example of the macroscopic approach

Answer 11

It is not possible to know the interactions between each of the different particles, to determine the pressure over a recipient.

Como en cálculo diferencial, para hacer una ecuación diferencial, tenemos que asegurar que el proceso sea continuo.

Question 12

Examples of thermodynamics applications:

Answer 12

Sumo wrestler.
A rock falling.
A house with solar panels.
Gas turbines.
Combined cycle plant.
Concentrated solar power plants.
Eolic turbines.

Question 13

Measurement units

Answer 13

• International system.

* English Systems.

Question 14

Force

SI: F = …

Answer 14

SI: F = ma = kg m / s2 = Newton

Question 15

Force

ES: 1 lbf = …

Answer 15

ES: 1 lbf = 32.174 lbm pies / s2

Question 16

Force

1 kgf = …

Answer 16

1 kgf = 9.81 N

The weight of 1kg at sea level.

Question 17

Work

SI: W = …

Answer 17

SI: W = F d = N m = 1 Joule

Question 18

Work

ES: 1 BTU = …

Answer 18

ES: 1 BTU = 1.0551 KJ

Energy necessary yo increase 1 F the temperature of 1 lbm at 68 F.

Question 19

Work

Calorie = …

Answer 19

Calorie = 4.1868 Joule

Energy required to increase in 1 C the temperature of 1 g of water at 14.5 C.

Question 20

Power

P = …

Answer 20

P = W / t

Question 21

What does power mean?

Answer 21

Capacity to do the job.

Question 22

Power

SI: 1 J / s = …

Answer 22

SI: 1 J / s = 1 watt

Question 23

Power

ES: 1 HP = …

Answer 23

ES: 1 HP = 746 w

Question 24

Basic concepts

Answer 24

Subtitle

Question 25

System and surroundings System: ...

Answer 25

A quantity of matter or a region in a space chosen for study. Está definido por quien va a realizar el estudio, hay que definirlo bien. Depende del objeto de estudio.

Question 26

System and surroundings Surroundings: ...

Answer 26

Mass or region outside the system.

Question 27

System and surroundings Boundary: ...

Answer 27

The real or imaginary surface that separates the system from its surroundings. The boundary could be fixed or movable. Ver dibujo.

Question 28

Different types of systems

Answer 28

Open: The matter and the energy go in and out. Ex, tobera and turbine. Closed: Ex, gas with a piston and internal combustion engine. Isolated: Everything occurs inside, neither the matter nor the energy go in or out. Ver dibujos.

Question 29

Properties of a system Property

Answer 29

Any characteristic of a system is called property.

Question 30

Familiar properties

Answer 30

Pressure (P), temperature (T), volume (V) and mass (M).

Question 31

Less familiar properties

Answer 31

``` Viscosity Thermal conductivity Modulus of elasticity Thermal expansion coefficient Electric resistivity ```

Question 32

Properties can be classified in

Answer 32

Intensive properties: temperature, pressure, density. Extensive (depend of the size of the system): total volume, total mass. Specific properties (extensive properties per unit mass): specific volume, specific energy.

Question 33

State and equilibrium What characterize a system in a certain moment?

Answer 33

The properties characterize a system in a certain moment. When the properties maintain fixed values, this describes an specific equilibrium state.

Question 34

State and equilibrium What does thermodynamics study?

Answer 34

Thermodynamics studies equilibrium states. There are no unbalanced potentials in the system (Thermal Eq, Mechanical Eq, Phase Eq, Chemical Eq).

Question 35

Process and cycle Proces: ...

Answer 35

Any change that a system undergoes from one state to another.

Question 36

Process and cycle Trayectory: ...

Answer 36

The serie of states that a system undergoes during a process.

Question 37

Process and cycle A system is said to have...

Answer 37

A system is said to have undergone cycle if it returns to its initial state at the end of the process.

Question 38

See the property diagram to help to visualize the processes.

Answer 38

...

Question 39

Different types of processes Quasi static.

Answer 39

When a process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times, it is called a quasi-static or quasi-equilibrium process.

Question 40

Different types of processes See drawings a) and b)

Answer 40

...

Question 41

Different types of processes See drawing of system properties and trajectory properties.

Answer 41

...

Question 42

Adicional types of processes

Answer 42

Isothermal Process: constant temperature. Isobaric Process: constant pressure. Adiabatic Process: there is no heat exchange. Isochoric Process: constant volume. Ver diagrama de esto.