Lecture 1, Thermodynamic Properties BASIC THERMODYNAMIC Lecture 1, Thermodynamic Properties

Thermodynamic Properties of a system Intro… Thermodynamic Properties of a system Temperature Pressure Volume & specific volume Mass & Weight Density Specific gravity Humidity; Absolute & Relative humidity Intensive and Extensive Properties

Hold on a minute…! What is a thermodynamic system? System is whatever we want to study, subject of the analysis. Closed system Closed system always contains the same amount of matter. System Control volume Mass may cross the boundary of the control volume.

Temperature

TEMPERATURE Definition : The degree of hotness or coldness of a body or environment (corresponding to its molecular activity). Is a measure of the average heat or thermal energy of the particles in a substance

TEMPERATURE Temperature is a measure of… The total amount of (thermal) energy in an object How much heat an object gives off How fast the molecules in an object are moving

TEMPERATURE DEFINITION Is a measure of the average energy of motion, or Kinetic Energy , of particles in matter E = ½ . m. V2

for measuring temperature HOW DO WE MEASURE TEMPERATURE? THERMOMETER Instrument or device for measuring temperature

TEMPERATURE TYPES of THERMOMETER Liquid-in-glass thermometer The property measured is the length of the liquid column inside a glass tube. (Hg, alcohol ether) Thermocouple sense temperature by voltage difference generated by conductors subjected to thermal difference.

TEMPERATURE Platinum resistance thermometer The property measured is the electrical resistance of a piece of sensing' material. Pyrometer (radiation thermometer) non-contact device that estimate temperature based on material’s thermal radiation.

TEMPERATURE CELCIUS (centigrade)   C TEMPERATURE SCALE Boiling water temp.  100 C Melting ice temp.  0 C

FAHRENHEIT   F Boiling water temp.  212 F Melting ice temp.  32 F

Correlation between degree C & degree F 100 0 C or 32 F C or 212 F C  (100 – 0) /100 F  (212 - 32) /100

Correlation between degree C & degree F ℉= 𝟗 𝟓 ∙℃ +𝟑𝟐 ℃= 𝟓 𝟗 ∙ ℉−𝟑𝟐

ABSOLUTE TEMPERATURE SCALE THE CONCEPT OF ABSOLUTE TEMPERATURE ABSOLUTE ZERO Temperature where all molecular motion would cease and no additional heat could be extracted from the substance ABSOLUTE TEMPERATURE SCALE Kelvin  K Rankine  °R

TEMPERATURE Temperature Scale Absolute Temp. scale Celcius  C Kelvin  K Fahrenheit  F Rankine  R

K = C + 273.15 TEMPERATURE TEMPERATURE SCALE  C & K Kelvin Celcius 373 100  K = C + 273.15 273   0  0  - 273

TEMPERATURE TEMPERATURE SCALE  F & R Note: 459.67  460 Rankine Fahrenheit Note: 459.67  460 672 212    460  32  0  - 459.4

TEMPERATURE TEMPERATURE SCALE  K & R Note: 459.67  460 Kelvin Rankine Note: 459.67  460 373   672    273  460  0   0

? ? TEMPERATURE TEMPERATURE  exercised So, C  K & F K  C & F F  C & K R  F & K ? ? What temperature is that the C and F have the same value

? TEMPERATURE  exercised PLEASE CONVERT: 25 C  K & F & R 300 K  C & F & R 410 F  C & K & R 600 R  F & K & C ?

Pressure

What is Pressure? F P = A Pressure is the measurement of a force exerted on a given area F [lb] A [in2] P [psi] F [N] A [m2] Pascal (Pa) Units  Others Units  Atm; mbar; mmHg

Pabs Pgauge P unit in [psia] means P unit in [psig] means Pgauge Pvc Alt. Pgauge Pabs Sea Level, P = 14.7 psi Pvc Patm Patm Pabs Absolute Datum Pabs = 0

Pabs Pgauge P unit in [psia] means P unit in [psig] means Pgauge Pabs Alt. Pgauge Pabs Sea Level, P = 14.7 psi Patm Absolute Datum Pabs = 0

Volume & Specific volume

Volume & Specific Volume V  spaces takes up by a three-dimensional object The specific volume (v) of a substance is The total volume (V) of that substance divided by the total mass (m) of that substance V v = m v = specific volume (ft3/lbm), (m3/kg) V = volume (ft3), (m3) m = mass (lbm), (kg)  = ? ( dalam v) Try to Derive! So,

Mass & Weight

Mass & Weight Definition Mass (m), Defined as amount of matter in a body (regardless of its volume or of any forces acting on it). The unit of mass is [kg] or [lbs]. Weight (W)), The name given to the force on an object due to gravity. The unit of weight is [N] or [lbf].

In aircraft, the term mass and weight often mixed up..!!! Mass & Weight Relation: W = weight m = mass g = gravity accel. = 9.81 m/s2 be Careful.... In aircraft, the term mass and weight often mixed up..!!!

Density & Specific Gravity

Density & Specific Gravity  , is mass per unit volume Measure of how tightly matter is crammed together ρ =     m     V where ρ = density (kg/m3) m = mass (kg) V = volume (m3) Specific Gravity or Relative Density The ratio of the density of substance to the density of water at 4oC

Humidity

Humidity & Relative humidity The amount of water vapor in the air. The relative humidity The amount of water vapor in the air (at a specific temperature) compared to the maximum amount of water vapor air could hold at that temperature, and is given as a percentage value.

Humidity & Relative humidity As the temperature decreases, the amount of moisture in the air doesn't change, but the relative humidity goes up (since the maximum amount of moisture that cooler air can hold is smaller).

Humidity & Relative humidity Exercise: If the actual water vapor content of the air is 10 grams per cubic meter and the water vapor capacity (saturated) is 20 grams per cubic meter, what is the relative humidity of that air?

Other Properties

Intensive & extensive properties Intensive property Physical quantity whose value does not depend on the amount of the substance for which it is measured (mass, m) Extensive property Physical quantity whose value is proportional to the size of the system it describes