Transcript Physical Principles of Respiratory Care

Physical Principles of
Respiratory Care
Egan Chapter 6
Physical Principles of Respiratory Care
I.
II.
III.
IV.
States of Matter
Change of State
Gas Behavior Under Changing Conditions
Fluid Dynamics
I. States of Matter
Internal Energy of Matter
B. Heat and the First Law of Thermodynamics
C. Heat Transfer
1.
Conduction
2.
Convection
3.
Radiation
4.
Evaporation and Condensation
D. Laws of Thermodynamics
1.
Internal Energy and Temperature
2.
Absolute Zero
3.
Temperature Scales
A.
I. States of Matter
Three primary states of matter:
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http://www.youtube.com/watch?v=j2KZmRIKea8
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I. States of Matter
Solids
 Have high degree of internal order
 Fixed volume and shape
 Strong mutual attractive force between atoms
 Molecules have the shortest distance to travel
before collision
 This motion referred to as a “jiggle”
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I. States of Matter
Liquids
 Have fixed volume, but adapt to shape of their
container
 Atoms exhibit less degree of mutual attraction
compared w/ solids
 Shape is determined by numerous internal &
external forces
Gases
 No fixed volume or shape; weak attractive forces
 Gas molecules exhibit rapid, random motion w/
frequent collisions
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A. Internal Energy of Matter
Energy matter possesses = internal energy
 Atoms of all matter at ordinary temperatures are in constant
motion
 Two major types of internal energy:
 Potential energy
 Energy of position (attractive forces between molecules)
 Weak in gas state
 Makes up most of internal energy in solids & liquids
 Kinetic energy
 Energy of motion
 Makes up most of gases internal energy
 All matter has some kinetic energy
 http://www.youtube.com/watch?v=0ASLLiuejAo&list=PLB7616
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B. Heat & the
First Law of Thermodynamics
Thermodynamics can refer to 2 subjects:
 Science studying the properties of matter at various
temperatures
 Kinetics, (speed) of reactions of matter at various
temperatures
Energy can be neither created nor destroyed
Energy gain by substance = energy lost by
surroundings
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C. Heat Transfer
When two objects of different temperature coexist,
heat will move from hotter to cooler object until
both are equal
 First Law of Thermodynamics
Heat Transfer can Occur by
 Conduction
 Convection
 Radiation
 Evaporation and Condensation
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C. Heat Transfer
1.
Conduction
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The transfer of heat by
direct contact between
hot and cold molecules
Heat transfer in solids
occurs mainly via
conduction
Thermal
ConductivityMeasure to
quantify heat transfer
between objects
 Metals have high level
C. Heat Transfer
• Solids,
particularly
metals have a
high level of
thermal
conductivity.
• The high
thermal
conductivity of
metal quickly
draws heat
away from the
skin, creating a
feeling of “cold.”
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C. Heat Transfer
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Convection currents
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2. Convection is heat
transfer through the
mixing of fluid
molecules at different
temperatures
(movement of the fluid)
 Heat transfer in both
liquids and gasses occurs
mainly by convection
C. Heat Transfer
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Radiant Warmer
3. Radiation
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Radiant heat transfer
occurs without direct
physical contact
C. Heat Transfer
4. Evaporation: The change
of state from liquid to
gas below boiling point
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Condensation: The
opposite of evaporation
D. Laws of Thermodynamics
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Three physical principles describe how energy is
handled & transferred:
1. Conservation of EnergyEnergy cannot be
created or destroyed
2. Thermodynamic EquilibriumGiven time all
systems will achieve lowest possible energy state
(entropy)
3. Impossibility of Achieving Absolute ZeroAt
absolute zero all processes cease & entropy is at
minimum
D. Laws of Thermodynamics
1.
Internal Energy and Temperature
 The temperature of an object is a measurement of
its internal kinetic energy
 The higher the temperature, the faster the
molecules that comprise the object are moving
The molecules of boiling water
move faster than molecules of
water at room temperature
because they have more kinetic
energy!
D. Laws of Thermodynamics
2.
Absolute Zero
 ConceptLowest possible temperature that can
be achieved
 Temperature = no kinetic energy
 Molecules cease to vibrate; object has no
measurable heat
 Scientists have not actually achieved it
D. Laws of Thermodynamics
3.
Temperature Scales
 Fahrenheit (F) & Celsius (C) scales based on
property of water
 0° C is freezing point of water
 - 273° C = kinetic molecular activity stops = 0 K
 Kelvin scale (K ) based on molecular motion
 Used by SI (Systeme Internationale) units
 Zero point = absolute zero
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D. Laws of Thermodynamics
3.
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Temperature Scales
D. Laws of Thermodynamics
3.
Temperature Scales
 Conversions:
 ° K = ° C + 273
 ° C = 5/9 (° F – 32)
 ° F = 9/5 °C + 32
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Internal Energy and Temperature
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1.
2.
3.
4.
5.
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8.
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Practice!
Convert 25°C to K
Convert 0°C to K
Convert 100 K to °C
Convert 54 K to °C
Convert 37°C to °F
Convert 20°C to °F
Convert 75° F to °C
Convert 100° F to °C
Equipment Required
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Vent with heated wire circuit attached.
Circuit with water traps