Termo Flashcards

1
Q

Common Phases of Substance

A

Solid, liquid & gas

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2
Q

Does not take on the shape or volume of its container

A

Solid

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3
Q

Absorb as much heat energy as it can without vaporizing

A

Saturated Liquid

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4
Q

Example of Saturated Liquid

A

Liquid Water at 100C & 1 atm

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5
Q

Liquid not saturated

A

Subcooled Liquid

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6
Q

Liquid and vapor of the same substance at the same temperature and pressure

A

Liquid-vapor mixture
two-phase

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7
Q

Ideal gas whose specific heats are constants

A

Perfect Gas

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8
Q

Vapor that is on the verge of condensing

A

Saturated Vapor

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9
Q

Example of Saturated Vapor

A

Steam at 100C & 1 atm

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10
Q

Absorb more energy than is needed merely to vaparize it. It wil not condense when small amounts of energy are removed

A

Superheated Vapor

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11
Q

Superheated vapor that behaves according to pV=mRT

A

Ideal Gas

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12
Q

Gas that does not behave according to ideal gas laws

A

Real Gas

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13
Q

Two or more pure gases together

A

Gas mixture

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14
Q

atmospheric gas

A

Vapor-gas mixture

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15
Q

Three dimensional surface that predicts a substance phase includes the following properties

A

Pressure
Temperature
Specific Volume
pvT diagram

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16
Q

Unique state at which solid, liquid and gaseouses phases can coexist

A

Triple point

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17
Q

(T/F) Thermodynamic properties of ideal gases do not depend on other thermodynamic properties

A

True. Changes in pressure do not affect changes in specific enthalpy when T constant. Changes un specific volume do not affect change in specific internal energy when T constant.

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18
Q

A process which no heat crosses the system boundary

A

Adiabatic process
Including isentropic and throttling process.

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19
Q

An adiabatic process which there is no entropy production. Is reversibec

A

Isentropic Process

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20
Q

An adiabatic process in which there is no change in enthalpy, but for which there a significant pressure drop

A

Throttling process

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21
Q

Isobaric Process

A

Constant Pressure Process

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22
Q

Isothermal Process

A

Constant Temperature Process

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23
Q

Isochoric Process

A

Constant volume process

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24
Q

A process that obeys the polytropic equation of state.

A

Polytropic process

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25
Q

Law: The net energy crossing the system boundary is the change in energy inside the system. Whether or not a process is reversible.
The work done in adiabatic process depends only on the systems endpoint conditions.

A

First Law of Thermodynimics

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26
Q

If no mass crosses the system boundaries, the system is

A

closed

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27
Q

If mass flows through the system across the system boundaries, the system is

A

open

28
Q

Example of Open Systems

A

Pumps, heat exchangers, jet engines, turbines, boilers

29
Q

Example of Closed System

A

Gas compressed by a piston

30
Q

System closed to both mass and energy, is an ____ system

A

isolated

31
Q

Qin, Qout, Win, Wout signs

A

Qin - heat entrando al sistema (+)
Qout - Heat saliendo del sistema (-)
Win - alrededores haciendo trabajo sobre el system (-)
Wout - system haciendo trabajo hacia los alrededores (+)

32
Q

Closed System - P constante

A

wb=p*deltaV

33
Q

Closed System - V constante

A

wb=0

34
Q

Closed system - T constante

A

wb = RTln(v2/v1) = RTln(p2/p1)

35
Q

Reversive work (Wrev) - Open systems

A

At the boundary, there is a pressure opposing fluid from entering the system. So the work required to cause the flow into the system against the Pexit is w_rev. It is work being done to the system (-)

36
Q

Substance Phase Determine Rules - Que es?
- T<Tsat @ P dada
- P > Psat @ T dada

A

Subcooled liquid

  1. Liquid Vapor Ragion
    - T = Tsat @ P dada
    - P = Psat @ T dada
  2. Superheated Vapor
    - T> Tsat @ P dada
    - P < Psat @ T dada
37
Q

Substance Phase Determine Rules - Que es?
- T = Tsat @ P dada
- P = Psat @ T dada

A

Liquid Vapor Region
- T = Tsat @ P dada
- P = Psat @ T dada

38
Q

Substance Phase Determine Rules - Que es?
- T> Tsat @ P dada
- P < Psat @ T dada

A

Superheated Vapor

39
Q

T-s diagram Rankine System

A

Boiler - P aumenta - T no cambia (no delta h)
Condenser (T no cambia P disminuye, no delta h)
Pump - T aumenta ( no delta s idealmente)
Turbnine - T disminuye ( no delta s idealmente)

40
Q

Law:
Environment: Entropia del ambiente siempre va a aumentar en un proceso real
Working fluid: Una sustancia puede ser devuelta a su estado original sin aumentar la entropia del sistema, solo en un sistema reversible
Equipment: A machine taht returns the working fluid to its original state require a heat sink. A machine that rejets more energy than the useful work it performs

A

2nd Law of Thermodynamics

41
Q

Cycle that takes heat and uses it to do work on the surroundings

A

Power Cycle

42
Q

Most efficient power cycle possible

A

Carnot Cycle

43
Q

Similar to Carnot Cycle except the compression process occurs in the liquid region

A

Rankine Cycle

44
Q

Four stroke cycle (Power Cycle)

A

Otto Cycle

45
Q

Dry-bulb Temperature (Tdb)

A

Temperature that a regular thermometer measure if exposed to air

46
Q

Wet-bulb Temperature Twb

A

Temperature of air that has gone through an adiabatic saturation process. It is measured with a thermometer that is covered with a water saturated cotton wick.

47
Q

Dew-point Temperature (Tdp)

A

This is the dry bulb temperature at which water starts to condense when moist air is cooled in a constant pressure process. Tdp = Tsat for the partial pressure vapor

48
Q

Tdb = Twb = Tdp

A

Saturated air

49
Q

Tdp< Twb < Tdb

A

Unsaturated air

50
Q

dQ=Tds

A

Proceso Reversible

51
Q

(T/F) 2nd Law of thermodynamics: It is impossible for a system working in a complete cycle to accomplish, as it sole effect, the transfer of ehat from a body at a given temperature to a body at a higher temperature

A

True - Calsius statement of 2nd Law of thermodynamics

52
Q

What are the processes in an ideal Otto Combustion cycle?

A

Two constant volume processes and two constant isentropic processes

53
Q

In which process is the maximum work output obtained?

A

In a reversible process. The difference between the maximum and the actual work output is the process irreversibility.

54
Q

Dalton Law of Partial Pressure

A

The total pressure of gas mixture is teh sum od the individual gases partial pressure.

55
Q

Energy that is given off when the fuel is burned

A

Heating Value

56
Q

Heating Value Units

A

Coal - KJ/kg
Oil - KJ/L
Gases - KJ/m3

57
Q

Heat Value Derived from enthalpy of formation is known as

A

Enthalpy of reaction / Heat of Reaction / Heat of combustion - deltaHr

58
Q

Exothermic Reaction

A

Chemical reactions that give off energy (negative enthalpy)

59
Q

Endothermic Reaction

A

Absorb energy (positive enthalpy)

60
Q

Hess Law

A

Enthalpy of reaction = sum of the enthalpies of formation of the products - sume of enthalpies of formation of the reactants.

61
Q

Molar weight of air

A

28.84 g/mol

62
Q

Volume of 1 mole of ideal gas at standard temperature and pressure is

A

22.4 L

63
Q

The complete combustion of hydrocarbon fuel are

A

carbon dioxided and water vapor

64
Q

When sulfure is present in the fuel, the normal product is

A

sulfur dioxide SO2

65
Q

When there is insufficient oxygen for complete combustion, ___ wil be formed

A

Carbon Monoxide (CO)

66
Q

Cuando se habla de una combustion de air es

A

O2 + 3.76N2