ME-THER
THERMODYNAMICS
Learning Plan – Module 1
Week 1 – 6 ( 18 hrs Sept 1 – October 9)
Week 1 – 2 (6 hrs Sept 2 and Sept 9) - Grading policies, course
syllabus, expectations.
• 1 - Basic Principles, Concepts and Definitions
Week 3 – 4 (6 hrs Sept 16 and 23)
• 2 - First Law of Thermodynamics – Conservation of Energy
Week 5 – 6 (6 hrs Sept 30 and October 7)
• 3 - Ideal Gas
Week 5 Oct 7 W– Preliminary Examination
Learning Plan – Module 1
Week 1 – 2 (6 hrs Sept 2 – Sept 9)
Lesson 1 - Basic Principles, Concepts and Definitions
Thermodynamics is a branch of physical sciences that treats various
phenomena of energy and related properties of matter, especially
the laws of transformation of heat into other forms of energy and
vice versa.
Systems of units
Newton’s law states that acceleration of a body is directly
proportional to force acting on it and inversely proportional to mass.
a = k F/m F = ma / k k = ma / F
where k is a proportional constant
Learning Plan – Module 1
cgs system: 1 dyne accelerates 1 gram mass at 1cm/sec2
mks system: 1 newton accelerates 1 kilogram mass at 1 m/sec2
fps system: 1 pound-force accelerates 1 slug mass at 1 ft/sec2
1g 1 dyne 1kg 1 newton 1 slug 1 lbf
a a a
1 cm/sec2 1 m/sec2 1 ft/sec2
k = 1 g-cm / dyne-sec2 k = 1 kg-m/N-sec2 k = 1 slug-ft/lbf-sec2
Question: How many dynes in 1 newton, where 1N = 1 kg-m / sec2
Answer : 1 x 105 dynes
Learning Plan – Module 1
Acceleration values
1 gram force accelerates a 1 gram mass at 980.66 cm/sec2
1 kg force accelerates a 1 kg mass at 9.8066 m/sec2
1 lb force accelerates a 1 lb mass at 32.174 ft/sec2
1gm 1 gf 1kgm 1 kgf 1 lbm 1 lbf
a a a
980.66 cm/sec2 9.8066 m/sec2 32.174 ft/sec2
k= 980.66 gm-cm/gf -s2 k= 9.8066 kgm-m/ kgf -s2 k= 32.174 lbm-ft/lbf-s2
Question: If 1 N = 1 kg-m/sec2 and 1 kgf = 9.8066 kgm-m/sec2, how
many Newtons in 1 kgf ? Answer : 1 kgf = 9.8066 N
Learning Plan – Module 1
Solution: Relation between Kilogram force (Kgf) and Newton (N)
k = 1 kg-m/N-sec2
k = 9.8066 kg-m/ kgf - s2
Equating k’s: 1 kg-m/N-sec2 = 9.8066 kg-m/ Kgf - s2
Therefore, 1 Kgf = 9.8066 N
Or, 1 Kgf = 9.8066 kg-m/ s2 x 1 N / 1 kg-m/ s2 = 9.8066 N
Question: How many Pound mass (lbm) is 1 slug? Ans: 32.174 lbm
k = 32.174 lbm-ft/lbf - s2
k = 1 slug-ft/lbf - s2
Equating k’s: 1 slug -ft/lbf - s2 = 32.174 lbm- ft/lbf - s2
Learning Plan – Module 1
Acceleration
A unit of force is one that produces 1 unit acceleration in a body of
1 unit of mass. F = mass x acceleration
1g 1 dyne 1kg 1 newton 1 slug 1 lbf
a = 1 cm/sec2 a = 1 m/sec2 a = 1 ft/sec2
1 dyne = 1 g x 1 cm/sec2 1 lbm 1 poundal
1 Newton = 1 kg x 1 m/sec2
1 lbf = 1 slug x 1 ft/sec2 a = 1 ft/sec2
1 poundal = 1 lbm x 1 ft/sec2
Learning Plan – Module 1
Mass and Weight
The mass of a body is the absolute quantity of matter in it.
The weight of a body means the force of gravity on the body.
F = ma / k or
m / k = F / a = Fg / g
where g = acceleration due to gravity produced by force Fg
a = acceleration produced by another force F
At or near the surface of the surface of the earth, k and g are
numerically equal, so are mass and Fg
End of lesson 1 / week 1 – next Activity #1 / week 1 in
Asynchronous period
Learning Plan – Module 1
Activity #1 – Lesson 1 / Week 1 Due: Sept 9, 2020 (week 2)
Problems:
1. What is the weight ( Kgf ) of a 66 kg-mass man at standard
condition? m = 66 kgm g = 9.8066 m/s2
2. What is the mass ( lbm ) of an object at standard condition which
weighs 50 lb ? Fg = 50 lbf g = 32.174 ft/s2
3. Five masses where the acceleration due to gravity is 30.5 ft/s2
are as follows: m1 = 500 gram mass, m2 = weighs 800 gram
force, m3 = 15 poundals, m4 = 3 lbf and m5 = 0.01 slug mass.
What is the total mass expressed in a) grams b) pounds c) slugs
30% presentation = 30
70% content / solution – accuracy = 70
Learning Plan – Module 1
Week 2 (3 hrs Sept 9 )
Lesson 1 - Basic Principles, Concepts and Definitions
Specific Volume, Density and Specific Weight
The density, ρ of a substance is its mass (not weight) per unit volume
ρ = m / V (rho)
The specific volume, ν is the volume per unit mass.
ν = V / m = 1/ ρ ( nu)
The specific weight , ɣ of a substance is the force due to gravity per
unit volume. ɣ = Fg / V (gamma)
Since the specific weight is to local acceleration of gravity , the
density is to standard acceleration. ɣ / g = ρ / k
Learning Plan – Module 1
ɣ / g = ρ / k
ρ = ɣ k /g
ɣ = ρ g / k
At or near the surface of the earth, k and g are numerically equal, so
are ρ and ɣ
Example: What is the specific weight of water at standard
condition.
g = 9.8066 m/s2 ρ = 1000 kg / m3
ɣ = ρ g / k
= 1000 kg / m3 x 9.8066 m /s2
9.8066 kg- m/ kgf - s2
= 1000 kgf /m3
Learning Plan – Module 1
Pressure
The standard reference atmospheric pressure is: Po
760 mm Hg or
29.92 inches Hg at 32 oF or
14.696 psi absolute (psia) or 14.7 psia
1 atmosphere (atm)
Measuring Pressure
1. By using manometers
2. By using pressure gages
By using manometers
Learning Plan – Module 1
By using pressure gages
Learning Plan – Module 1
Learning Plan – Module 1
Gage pressure
Learning Plan – Module 1
Solution
pg = ρ g hg / k P = F / A = N/m2
2
= 9.65 m/s2 ( 1878 kg / m3) (30 m)
1 kg-m/ N- s2
= 543,680 N/m2 = 543.68 KPa (gage)
NOTE : 1 PASCAL = 1 N / m2
1 KILO PASCAL (kPa) = 1000 N / m2
Pabs = Po + Pg = Po + 543.68 kPa = Po + 543.68 kPa (abs)
Learning Plan – Module 1
Atmospheric Pressure
Learning Plan – Module 1
Problem 1: A vertical column of water will be supported to what
height by standard atmospheric pressure?
P = ɣ h
Learning Plan – Module 1
Atmospheric Pressure
Problem
Sp gr of Hg = 13.6
P = ɣ h
ɣHg = sg ɣw
Learning Plan – Module 1
Absolute Pressure
Learning Plan – Module 1
Absolute Pressure
Ans : 54.5 psia = 375.78 kPa
Learning Plan – Module 1
Absolute Pressure
1 lbf = 1N / 0.2248
k = 1
1
Learning Plan – Module 1
Absolute Pressure
1 lbf = 1N / 0.2248
2
1
Learning Plan – Module 1
Temperature
Learning Plan – Module 1
Temperature
Learning Plan – Module 1
Temperature
Learning Plan – Module 1
Conservation of Mass
Learning Plan – Module 1
Conservation of Mass
where ρ = 1/ ν
m =
Learning Plan – Module 1
Conservation of Mass
Learning Plan – Module 1
Conservation of Mass
m = V ρ
m = A Ʋ ρ
Learning Plan – Module 1
Conservation of Mass
ρ = m / V
h = V / A
Learning Plan – Module 1
ACTIVITY 2
SOLVE THE FOLLOWING PROBLEMS 1 TO 11 AS YOUR
ASYNCHRONOUS ACTIVITY FOR WEEK 3 (SEPT 16) AND WEEK
4 (SEPT 23)
DUE ON SEPT 25, 2020 FRIDAY 5PM
Learning Plan – Module 1
Learning Plan – Module 1
Learning Plan – Module 1
Learning Plan – Module 1
DUE ON SEPT 25, 2020 FRI 5PM
Learning Plan – Module 1
Week 3 – 4 - Sept 16 and 23
• Lesson 2 - First Law of Thermodynamics
Thermodynamics
General Engineering
OCM
OCM
Thermodynamics
General Engineering
 States that the energy of an isolated system
remains constant.
 Energy cannot be created or destroyed in an
isolated system.
 It can only be transformed from one form to
another.
OCM
Thermodynamics
General Engineering
 Energy or stored capacity for performing work
possessed by a moving body, by virtue of its
momentum = F x d = N - m = Joule
KE = ½ mV2 kg – m2/s2 = kg-m/s2 - m
ΔKE = K2 – K1 = ½ m (V2
2 – V1
2)
Where ΔKE = change in Kinetic energy
V1
m m V2
OCM
Thermodynamics
General Engineering
 Energy due to its position or elevation
PE = mgh = kg-m/s2 – m
= N – m = Joule
ΔPE = P2 – P1 = mg (h2 – h1)
Where ΔPE = change in potential energy
h
Fg = mg
2
1
OCM
Thermodynamics
General Engineering
 Energy stored within a body or substance by
virtue of the activity and configuration of its
molecules and of the vibration of the atoms
within the molecules.
ΔU = U2 – U1 (m mass)
OCM
Thermodynamics
General Engineering
 Energy that is transferred between two
systems by a virtue of a temperature
difference
 Q is positive when heat is added to the body.
 Q is negative when heat is rejected by the
body.
OCM
Thermodynamics
General Engineering
 Three mechanisms:
1. Conduction – transfer of energy from the
more energetic particles of a substance to the
adjacent less energetic ones as a result of
interaction between particles
OCM
Thermodynamics
General Engineering
 Three mechanisms:
2. Convection – transfer of energy between a
solid surface and the adjacent fluid that is in
motion. It includes combined effects of
conduction and fluid motion
OCM
Thermodynamics
General Engineering
 Three mechanisms:
3. Radiation – transfer of energy due to the
emission of electromagnetic waves or
photons
OCM
Thermodynamics
General Engineering
 Three mechanisms:
OCM
Thermodynamics
General Engineering
 Energy transfer associated with a force acting
through a distance. W = F x d = Joules
 W is positive when work is done by the system.
 W is negative when work is done on the system.
W = ʃ1
2 p dV = F x d ( N-m)
Where p s pressure (N/m2) or Pascal and dV is
differential Volume (m3) = W (N-m) or Joule
OCM
Thermodynamics
General Engineering
 Flow work or flow energy is work done in
pushing a fluid across a boundary, usually into
or out of a system.
 Wf = FL = pAL
 Wf = pV
 ΔWf = Wf2 – Wf1 = p2V2 – p1V1
 Δ Wf = change in flow work
L
Area of surface
F V
system
Flow Work
Boundary
p
OCM
Thermodynamics
General Engineering
 Characteristics of steady flow system
◦ There is neither accumulation nor diminution of
mass within the system
◦ There is neither accumulation nor diminution of
energy within the system
◦ The state of the working substance at any point in
the system remains constant
OCM
Thermodynamics
General Engineering
 Energy entering System = Energy Leaving System
 P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W
 Q = (P2 - P1)+(K2 - K1)+ (Wf2 - Wf1)+(U2 - U1)+ W
 Q = ΔP+ ΔK + ΔWf + ΔU+ W
Where Q = Heat
P = Potential energy = mgh
K = Kinetic energy = ½ mV2
Wf = Flow work or Flow energy = pV = FL = pAL
U = Internal energy
W = Work = F d = pAL
OCM
Thermodynamics
General Engineering
P1
K1
Wf1
U1
Q
2
2
System
1
h1
h2
W
U2
Wf2
K2
P2
Datum level
1
OCM
Thermodynamics
General Engineering
 It is a thermodynamic quantity equivalent to the
total heat content of a system.
H = U + pV
Q = ΔU + W
Q = ΔH = H2 – H1
 The steady flow energy equation becomes
P1 + K1 + (Wf1+U1)+ Q = P2 + K2 + (Wf2+U2)+ W
P1 + K1 + H1 + Q = P2 + K2 + H2 + W
Q = ΔP+ ΔK + ΔH + W
OCM
Thermodynamics
General Engineering
1. During a steady flow process, the pressure of the working substance
drops from 200 to 20 psia. The speed increases from 200 to 1000 ft/sec.
The internal energy U of the open system decreases by 25 Btu/lb. the
specific volume increases from 1 to 8 ft3/lb. No heat is transferred.
a. Sketch an energy diagram.
b. Determine the Work per lb. Is it done on ( - ) or by (+) the substance?
c. Determine the Work in Hp for 10 lb per min. (1Hp = 42.4 Btu/min)
W
p1 = 200 psia p2 = 20 psia
v1 = 200 fps K1 K2 v2 = 1000 fps
ν1 = 1 ft 3 /lb Wf1 Wf2 ν2 = 8 ft 3 /lb
ΔU = -25 Btu/lb U1 U2 Q = 0
Energy System
P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W
+
_
OCM
Thermodynamics
General Engineering
Assume 1 lbm of substance
K1= ½ mV2/k = (200 ft/sec)2/ 2 (32.174 lbm-ft/lbf-sec2) (778 lbf-ft/Btu)
= 0.80 Btu/lbm
K2 = ½ mV2/k = ( 1000) 2 / 2 (32.174) (778) = 19.97 Btu/lbm
Wf1 = p V = (200 lbf/in2) ( 144 in2/ft2) (1 ft3/lbm) / 778 ft-lbf/Btu
= 37.02 Btu/lbm
Wf2 = p V = 20 (144) (8) / 778 = 29.61 Btu / lbm
No heat is transferred, thus, Q = 0, assume same elevation, no ΔP
P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W
K1 + Wf1 + U1 = K2 + Wf2 + U2 + W
0.8 + 37.02 = 19.97 + 29.61 + (U2 - U1 ) + W
0.8 + 37.02 = 19.97 + 29.61 + (- 25 ) + W
W = + 13.24 Btu / lbm (positive so W is done by the substance)
W = 13.24 Btu/lbm ( 10 lbm /min) / 42.4 Btu / min / Hp = 3.12 Hp
OCM
Thermodynamics
General Engineering
2. Steam is supplied to a fully loaded 100 hp turbine at 200 psia with U1 =
1163.3 Btu/lb, V1 = 2.65 ft3/lb and v1 = 400 ft/sec. Exhaust is at 1 psia with
U2 = 925 Btu/lb, V2 = 294 ft3/lb and v2 = 1100 ft/sec. The heat loss from
the steam in the turbine is 10 Btu/lb. Neglect Potential energy change,
determine ,
a. Work per lb of steam
b. Steam flow rate in lb/hour (1Hp = 2544 Btu/hr) = 42.4 x 60
P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W
K1 + Wf1 + U1 + Q = K2 + Wf2 + U2 + W
K1= ½ mV2/k = 400 2 /2 (32.174)(778) = 3.2 Btu/lbm
K2 = ½ mV2/k = 1100 2 / 2 (32.174) (778) = 24.17 Btu/lbm
Wf1 = p V = (200) ( 144) (2.65) / 778 = 98.10 Btu/lbm
Wf2 = p V = (1) (144) (294) / 778 = 54.42 Btu/lbm
3.2 + 98.10 + 1163.3 + (- 10) = 24.17 + 54.42 + 925 + W
W = 251.01 Btu / lbm
Steam Flow = 100 Hp (2544 Btu/hr /Hp) / 251.01 Btu/lbm = 1014 lbm/hr
OCM
Thermodynamics
General Engineering
1. Steam enters a turbine with an enthalpy of 1292 Btu/lb
and leaves with an enthalpy of 1098 Btu/lb. The
transferred heat is 13 Btu/lb. What is the Work in
Btu/min and in Hp for a flow of 2 lb/sec. Ans. 512.3
Hp
2. It could be (1292-1098)-13 *2 = 362 BTU/sec ->21720 BTU/min
2. A thermodynamic steady flow system receives 4.56
kg/min of fluid (mass flow rate) where p1 = 137.9 kPa, ν1
= 0.0388 m 3/kg, v1 = 122 m/sec and U1 = 17.16
kJoules/kg. The fluid leaves the system at a boundary
where p2 = 551.6 kPa, ν2 = 0.193 m 3/kg, v2 = 183 m/sec
and U2 = 52.8 kJoules/kg. During passage through the
system, the fluid leaves 3,000 Joules/sec of Heat.
Determine the Work.
Ans. W = - 486 kJoules / min
OCM
Thermodynamics
General Engineering
 It is the quantity of heat required to change
the temperature of unit mass through one
degree.
 Ration of specific heats
k = cp/cv > 1
OCM
Thermodynamics
General Engineering
 Based on Joule’s Law,
ΔU = mcv (T2 – T1)
whether the volume remains constant or not.
OCM
Thermodynamics
General Engineering
 Based on Joule’s Law,
ΔH = mcp (T2 – T1)
whether the pressure remains constant or
not.
OCM
Thermodynamics
General Engineering
 H = U + pV
 pV = RT
 cp dT = cv dT + R dT
 cp = cv + R
 cv = R/ k – 1
 cp =kR/ k - 1
Learning Plan – Module 1
Week 5 – 6 Sept 30 and Oct 7
• Preliminary Examination – Oct 7 W
• Lesson 3 - Ideal Gas
Thermodynamics
General Engineering
OCM
OCM
Thermodynamics
General Engineering
 Vapor phase of a
substance when it
is above the critical
temperature
 Has a single
defined
thermodynamic
state at room
temperature
 A gas that is not far
from the state of
condensation
 Mixture of two
phases at room
temperature
OCM
Thermodynamics
General Engineering
OCM
Thermodynamics
General Engineering
Simply because it conforms to
the simple perfect gas laws!
OCM
Thermodynamics
General Engineering
 Air
 Nitrogen
 Oxygen
 Hydrogen
 Helium
 Argon
 Neon
 Krypton
 Heavier gases (carbon dioxide)
OCM
Thermodynamics
General Engineering
 Any equation that relates the pressure,
temperature and specific volume of a
substance.
OCM
Thermodynamics
General Engineering
OCM
Thermodynamics
General Engineering
 It is different for each gas.
 R = Ru/M
where: Ru = Universal gas constant
M = Molar mass/mol. Weight
OCM
Thermodynamics
General Engineering
 Same for all substances
 Ru Values: 8.314 kJ/kMol.K
8.314 kPa.m3/kmol.K
0.08314 bar.m3/kmol.K
1.986 Btu/lbmol.R
10.73 psia.ft3/lbmol.R
1545 ft.lbf/lbmol.R
OCM
Thermodynamics
General Engineering
 Mass of one mole, also called as gram-mole
(gmol), of a substance in grams
 m = MN
where: m = mass of system
M = molar mass
N = mole number
OCM
Thermodynamics
General Engineering
1. Determine the mass of the air in a room
whose dimensions are 4m x 5m x 6m at 100
kPa and 25 degC. Gas constant of air is 0.287
kPa.m3/kg.K.
OCM
Thermodynamics
General Engineering
2. The volume of a 7 x 13 ft tank is 543.3 cu.ft.
It contains air at 180 psig and 75 degF. How
many 1 cu.ft. drums can be filled to 60 psig
and 70 degF if its assumed that the air
temperature in the tank remains at 75 degF.
The drums have been sitting around in the
atmosphere which is at 14.7 psia and 70
degF.
OCM
Thermodynamics
General Engineering
3. Two vessels X and Y of different sizes are
connected by a pipe with a valve. Vessel X
contains 164 L of air at 3246.87 kPa, 90
degC. Vessel Y, of unknown volume, contains
air at 70.5 kPa, 5.6 degC. The valve is opened
and when the properties have been
determined, it is found that pm = 1500 kPa,
tm = 40.5 degC. What is the volume of vessel
B?
OCM
Thermodynamics
General Engineering
 Degree of disorder or randomness in the
system.
 It is the property of a substance which
remains constant if no heat enters or leaves
the substance, while it does work or alters its
volume, but which increases or diminishes a
small amount of heat enter or leave.
ΔS = mc ln(T2/T1)
OCM
Thermodynamics
General Engineering
4. For a certain ideal gas R = 25.8 ft.lb/lb.R
and k = 1.09,
a) What are the values of cp and cv ?
b) What mass of this gas would occupy a
volume of 15 cu.ft at 75 psia and 80 F?
c) If 30 BTU are transferred to this gas at
constant volume in (b), what are the
resulting temperature and pressure?
OCM
Thermodynamics
General Engineering
5. The specific heat of superheated steam at
approximately 150 kPa can be determined by
the equation
What is the enthalpy change between 300 ºC
and 700 ºC for 3 kg of steam? Compare with
the steam table (2565 kJ).
OCM
Thermodynamics
General Engineering
6. A 10 ft3 tank contains gas at a pressure of
500 psia, temperature of 85 degF and a
weight of 25 pounds. A part of the gas was
discharged and the temperature and pressure
changed to 70 degF and 300 psia,
respectively. Heat was applied and the
temperature was back to 85 degF. Find the
final weight, volume and pressure of the gas.
OCM
Thermodynamics
General Engineering
7. A motorist equips his automobile tires with
a relief-type valve so that the pressure inside
the tire will never willexceed 240 kPa (gage). He
starts a trip with a pressure of 200 kPa (gage) and
a temperature of 23 degC in the tires.During the
long drive, the temperature of the air in the tires
reaches 83 degC. Each tire contains 0.11 kg of air.
Determine (a) the mass of air escaping each tire, (b)
the pressure of the tire when the temperature
returns to 23degree Celsius.
Use R = 287.08 N.m/kg.K
OCM
Thermodynamics
General Engineering
8. An automobile tire contains 3730 cu in. of air at
32 psig and 80 degF. R = 53.342 lb.ft/lb.R
(a) What mass of air is in the tire?
(b) In operation, the air temperature increases to 145
degF. If the tire is inflexible, what is the resulting
percentage increase in gage pressure?
(c) What mass of the 145 degF air must be bled off to
reduce the pressure back to its original value?
OCM
Thermodynamics
General Engineering
Guidelines:
 With Front Page
 Margin: 1x1x1x1 (Visible)
 Engineering Lettering
 Problem Statement and Solution
 Box your final answers and round off up to two (2)
decimal places.
 CHAPTER 3: REVIEW PROBLEM
No. 6 (A 6 m3 tank…) and
No. 8 (A spherical balloon..)

heat, work and energy topic for thermodynamics

  • 1.
  • 2.
    Learning Plan –Module 1 Week 1 – 6 ( 18 hrs Sept 1 – October 9) Week 1 – 2 (6 hrs Sept 2 and Sept 9) - Grading policies, course syllabus, expectations. • 1 - Basic Principles, Concepts and Definitions Week 3 – 4 (6 hrs Sept 16 and 23) • 2 - First Law of Thermodynamics – Conservation of Energy Week 5 – 6 (6 hrs Sept 30 and October 7) • 3 - Ideal Gas Week 5 Oct 7 W– Preliminary Examination
  • 3.
    Learning Plan –Module 1 Week 1 – 2 (6 hrs Sept 2 – Sept 9) Lesson 1 - Basic Principles, Concepts and Definitions Thermodynamics is a branch of physical sciences that treats various phenomena of energy and related properties of matter, especially the laws of transformation of heat into other forms of energy and vice versa. Systems of units Newton’s law states that acceleration of a body is directly proportional to force acting on it and inversely proportional to mass. a = k F/m F = ma / k k = ma / F where k is a proportional constant
  • 4.
    Learning Plan –Module 1 cgs system: 1 dyne accelerates 1 gram mass at 1cm/sec2 mks system: 1 newton accelerates 1 kilogram mass at 1 m/sec2 fps system: 1 pound-force accelerates 1 slug mass at 1 ft/sec2 1g 1 dyne 1kg 1 newton 1 slug 1 lbf a a a 1 cm/sec2 1 m/sec2 1 ft/sec2 k = 1 g-cm / dyne-sec2 k = 1 kg-m/N-sec2 k = 1 slug-ft/lbf-sec2 Question: How many dynes in 1 newton, where 1N = 1 kg-m / sec2 Answer : 1 x 105 dynes
  • 5.
    Learning Plan –Module 1 Acceleration values 1 gram force accelerates a 1 gram mass at 980.66 cm/sec2 1 kg force accelerates a 1 kg mass at 9.8066 m/sec2 1 lb force accelerates a 1 lb mass at 32.174 ft/sec2 1gm 1 gf 1kgm 1 kgf 1 lbm 1 lbf a a a 980.66 cm/sec2 9.8066 m/sec2 32.174 ft/sec2 k= 980.66 gm-cm/gf -s2 k= 9.8066 kgm-m/ kgf -s2 k= 32.174 lbm-ft/lbf-s2 Question: If 1 N = 1 kg-m/sec2 and 1 kgf = 9.8066 kgm-m/sec2, how many Newtons in 1 kgf ? Answer : 1 kgf = 9.8066 N
  • 6.
    Learning Plan –Module 1 Solution: Relation between Kilogram force (Kgf) and Newton (N) k = 1 kg-m/N-sec2 k = 9.8066 kg-m/ kgf - s2 Equating k’s: 1 kg-m/N-sec2 = 9.8066 kg-m/ Kgf - s2 Therefore, 1 Kgf = 9.8066 N Or, 1 Kgf = 9.8066 kg-m/ s2 x 1 N / 1 kg-m/ s2 = 9.8066 N Question: How many Pound mass (lbm) is 1 slug? Ans: 32.174 lbm k = 32.174 lbm-ft/lbf - s2 k = 1 slug-ft/lbf - s2 Equating k’s: 1 slug -ft/lbf - s2 = 32.174 lbm- ft/lbf - s2
  • 7.
    Learning Plan –Module 1 Acceleration A unit of force is one that produces 1 unit acceleration in a body of 1 unit of mass. F = mass x acceleration 1g 1 dyne 1kg 1 newton 1 slug 1 lbf a = 1 cm/sec2 a = 1 m/sec2 a = 1 ft/sec2 1 dyne = 1 g x 1 cm/sec2 1 lbm 1 poundal 1 Newton = 1 kg x 1 m/sec2 1 lbf = 1 slug x 1 ft/sec2 a = 1 ft/sec2 1 poundal = 1 lbm x 1 ft/sec2
  • 8.
    Learning Plan –Module 1 Mass and Weight The mass of a body is the absolute quantity of matter in it. The weight of a body means the force of gravity on the body. F = ma / k or m / k = F / a = Fg / g where g = acceleration due to gravity produced by force Fg a = acceleration produced by another force F At or near the surface of the surface of the earth, k and g are numerically equal, so are mass and Fg End of lesson 1 / week 1 – next Activity #1 / week 1 in Asynchronous period
  • 9.
    Learning Plan –Module 1 Activity #1 – Lesson 1 / Week 1 Due: Sept 9, 2020 (week 2) Problems: 1. What is the weight ( Kgf ) of a 66 kg-mass man at standard condition? m = 66 kgm g = 9.8066 m/s2 2. What is the mass ( lbm ) of an object at standard condition which weighs 50 lb ? Fg = 50 lbf g = 32.174 ft/s2 3. Five masses where the acceleration due to gravity is 30.5 ft/s2 are as follows: m1 = 500 gram mass, m2 = weighs 800 gram force, m3 = 15 poundals, m4 = 3 lbf and m5 = 0.01 slug mass. What is the total mass expressed in a) grams b) pounds c) slugs 30% presentation = 30 70% content / solution – accuracy = 70
  • 10.
    Learning Plan –Module 1 Week 2 (3 hrs Sept 9 ) Lesson 1 - Basic Principles, Concepts and Definitions Specific Volume, Density and Specific Weight The density, ρ of a substance is its mass (not weight) per unit volume ρ = m / V (rho) The specific volume, ν is the volume per unit mass. ν = V / m = 1/ ρ ( nu) The specific weight , ɣ of a substance is the force due to gravity per unit volume. ɣ = Fg / V (gamma) Since the specific weight is to local acceleration of gravity , the density is to standard acceleration. ɣ / g = ρ / k
  • 11.
    Learning Plan –Module 1 ɣ / g = ρ / k ρ = ɣ k /g ɣ = ρ g / k At or near the surface of the earth, k and g are numerically equal, so are ρ and ɣ Example: What is the specific weight of water at standard condition. g = 9.8066 m/s2 ρ = 1000 kg / m3 ɣ = ρ g / k = 1000 kg / m3 x 9.8066 m /s2 9.8066 kg- m/ kgf - s2 = 1000 kgf /m3
  • 12.
    Learning Plan –Module 1 Pressure The standard reference atmospheric pressure is: Po 760 mm Hg or 29.92 inches Hg at 32 oF or 14.696 psi absolute (psia) or 14.7 psia 1 atmosphere (atm) Measuring Pressure 1. By using manometers 2. By using pressure gages
  • 13.
  • 14.
    Learning Plan –Module 1 By using pressure gages
  • 15.
  • 16.
    Learning Plan –Module 1 Gage pressure
  • 17.
    Learning Plan –Module 1 Solution pg = ρ g hg / k P = F / A = N/m2 2 = 9.65 m/s2 ( 1878 kg / m3) (30 m) 1 kg-m/ N- s2 = 543,680 N/m2 = 543.68 KPa (gage) NOTE : 1 PASCAL = 1 N / m2 1 KILO PASCAL (kPa) = 1000 N / m2 Pabs = Po + Pg = Po + 543.68 kPa = Po + 543.68 kPa (abs)
  • 18.
    Learning Plan –Module 1 Atmospheric Pressure
  • 19.
    Learning Plan –Module 1 Problem 1: A vertical column of water will be supported to what height by standard atmospheric pressure? P = ɣ h
  • 20.
    Learning Plan –Module 1 Atmospheric Pressure Problem Sp gr of Hg = 13.6 P = ɣ h ɣHg = sg ɣw
  • 21.
    Learning Plan –Module 1 Absolute Pressure
  • 22.
    Learning Plan –Module 1 Absolute Pressure Ans : 54.5 psia = 375.78 kPa
  • 23.
    Learning Plan –Module 1 Absolute Pressure 1 lbf = 1N / 0.2248 k = 1 1
  • 24.
    Learning Plan –Module 1 Absolute Pressure 1 lbf = 1N / 0.2248 2 1
  • 25.
    Learning Plan –Module 1 Temperature
  • 26.
    Learning Plan –Module 1 Temperature
  • 27.
    Learning Plan –Module 1 Temperature
  • 28.
    Learning Plan –Module 1 Conservation of Mass
  • 29.
    Learning Plan –Module 1 Conservation of Mass where ρ = 1/ ν m =
  • 30.
    Learning Plan –Module 1 Conservation of Mass
  • 31.
    Learning Plan –Module 1 Conservation of Mass m = V ρ m = A Ʋ ρ
  • 32.
    Learning Plan –Module 1 Conservation of Mass ρ = m / V h = V / A
  • 33.
    Learning Plan –Module 1 ACTIVITY 2 SOLVE THE FOLLOWING PROBLEMS 1 TO 11 AS YOUR ASYNCHRONOUS ACTIVITY FOR WEEK 3 (SEPT 16) AND WEEK 4 (SEPT 23) DUE ON SEPT 25, 2020 FRIDAY 5PM
  • 34.
  • 35.
  • 36.
  • 37.
    Learning Plan –Module 1 DUE ON SEPT 25, 2020 FRI 5PM
  • 38.
    Learning Plan –Module 1 Week 3 – 4 - Sept 16 and 23 • Lesson 2 - First Law of Thermodynamics
  • 39.
  • 40.
    OCM Thermodynamics General Engineering  Statesthat the energy of an isolated system remains constant.  Energy cannot be created or destroyed in an isolated system.  It can only be transformed from one form to another.
  • 41.
    OCM Thermodynamics General Engineering  Energyor stored capacity for performing work possessed by a moving body, by virtue of its momentum = F x d = N - m = Joule KE = ½ mV2 kg – m2/s2 = kg-m/s2 - m ΔKE = K2 – K1 = ½ m (V2 2 – V1 2) Where ΔKE = change in Kinetic energy V1 m m V2
  • 42.
    OCM Thermodynamics General Engineering  Energydue to its position or elevation PE = mgh = kg-m/s2 – m = N – m = Joule ΔPE = P2 – P1 = mg (h2 – h1) Where ΔPE = change in potential energy h Fg = mg 2 1
  • 43.
    OCM Thermodynamics General Engineering  Energystored within a body or substance by virtue of the activity and configuration of its molecules and of the vibration of the atoms within the molecules. ΔU = U2 – U1 (m mass)
  • 44.
    OCM Thermodynamics General Engineering  Energythat is transferred between two systems by a virtue of a temperature difference  Q is positive when heat is added to the body.  Q is negative when heat is rejected by the body.
  • 45.
    OCM Thermodynamics General Engineering  Threemechanisms: 1. Conduction – transfer of energy from the more energetic particles of a substance to the adjacent less energetic ones as a result of interaction between particles
  • 46.
    OCM Thermodynamics General Engineering  Threemechanisms: 2. Convection – transfer of energy between a solid surface and the adjacent fluid that is in motion. It includes combined effects of conduction and fluid motion
  • 47.
    OCM Thermodynamics General Engineering  Threemechanisms: 3. Radiation – transfer of energy due to the emission of electromagnetic waves or photons
  • 48.
  • 49.
    OCM Thermodynamics General Engineering  Energytransfer associated with a force acting through a distance. W = F x d = Joules  W is positive when work is done by the system.  W is negative when work is done on the system. W = ʃ1 2 p dV = F x d ( N-m) Where p s pressure (N/m2) or Pascal and dV is differential Volume (m3) = W (N-m) or Joule
  • 50.
    OCM Thermodynamics General Engineering  Flowwork or flow energy is work done in pushing a fluid across a boundary, usually into or out of a system.  Wf = FL = pAL  Wf = pV  ΔWf = Wf2 – Wf1 = p2V2 – p1V1  Δ Wf = change in flow work L Area of surface F V system Flow Work Boundary p
  • 51.
    OCM Thermodynamics General Engineering  Characteristicsof steady flow system ◦ There is neither accumulation nor diminution of mass within the system ◦ There is neither accumulation nor diminution of energy within the system ◦ The state of the working substance at any point in the system remains constant
  • 52.
    OCM Thermodynamics General Engineering  Energyentering System = Energy Leaving System  P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W  Q = (P2 - P1)+(K2 - K1)+ (Wf2 - Wf1)+(U2 - U1)+ W  Q = ΔP+ ΔK + ΔWf + ΔU+ W Where Q = Heat P = Potential energy = mgh K = Kinetic energy = ½ mV2 Wf = Flow work or Flow energy = pV = FL = pAL U = Internal energy W = Work = F d = pAL
  • 53.
  • 54.
    OCM Thermodynamics General Engineering  Itis a thermodynamic quantity equivalent to the total heat content of a system. H = U + pV Q = ΔU + W Q = ΔH = H2 – H1  The steady flow energy equation becomes P1 + K1 + (Wf1+U1)+ Q = P2 + K2 + (Wf2+U2)+ W P1 + K1 + H1 + Q = P2 + K2 + H2 + W Q = ΔP+ ΔK + ΔH + W
  • 55.
    OCM Thermodynamics General Engineering 1. Duringa steady flow process, the pressure of the working substance drops from 200 to 20 psia. The speed increases from 200 to 1000 ft/sec. The internal energy U of the open system decreases by 25 Btu/lb. the specific volume increases from 1 to 8 ft3/lb. No heat is transferred. a. Sketch an energy diagram. b. Determine the Work per lb. Is it done on ( - ) or by (+) the substance? c. Determine the Work in Hp for 10 lb per min. (1Hp = 42.4 Btu/min) W p1 = 200 psia p2 = 20 psia v1 = 200 fps K1 K2 v2 = 1000 fps ν1 = 1 ft 3 /lb Wf1 Wf2 ν2 = 8 ft 3 /lb ΔU = -25 Btu/lb U1 U2 Q = 0 Energy System P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W + _
  • 56.
    OCM Thermodynamics General Engineering Assume 1lbm of substance K1= ½ mV2/k = (200 ft/sec)2/ 2 (32.174 lbm-ft/lbf-sec2) (778 lbf-ft/Btu) = 0.80 Btu/lbm K2 = ½ mV2/k = ( 1000) 2 / 2 (32.174) (778) = 19.97 Btu/lbm Wf1 = p V = (200 lbf/in2) ( 144 in2/ft2) (1 ft3/lbm) / 778 ft-lbf/Btu = 37.02 Btu/lbm Wf2 = p V = 20 (144) (8) / 778 = 29.61 Btu / lbm No heat is transferred, thus, Q = 0, assume same elevation, no ΔP P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W K1 + Wf1 + U1 = K2 + Wf2 + U2 + W 0.8 + 37.02 = 19.97 + 29.61 + (U2 - U1 ) + W 0.8 + 37.02 = 19.97 + 29.61 + (- 25 ) + W W = + 13.24 Btu / lbm (positive so W is done by the substance) W = 13.24 Btu/lbm ( 10 lbm /min) / 42.4 Btu / min / Hp = 3.12 Hp
  • 57.
    OCM Thermodynamics General Engineering 2. Steamis supplied to a fully loaded 100 hp turbine at 200 psia with U1 = 1163.3 Btu/lb, V1 = 2.65 ft3/lb and v1 = 400 ft/sec. Exhaust is at 1 psia with U2 = 925 Btu/lb, V2 = 294 ft3/lb and v2 = 1100 ft/sec. The heat loss from the steam in the turbine is 10 Btu/lb. Neglect Potential energy change, determine , a. Work per lb of steam b. Steam flow rate in lb/hour (1Hp = 2544 Btu/hr) = 42.4 x 60 P1 + K1 + Wf1 + U1 + Q = P2 + K2 + Wf2 + U2 + W K1 + Wf1 + U1 + Q = K2 + Wf2 + U2 + W K1= ½ mV2/k = 400 2 /2 (32.174)(778) = 3.2 Btu/lbm K2 = ½ mV2/k = 1100 2 / 2 (32.174) (778) = 24.17 Btu/lbm Wf1 = p V = (200) ( 144) (2.65) / 778 = 98.10 Btu/lbm Wf2 = p V = (1) (144) (294) / 778 = 54.42 Btu/lbm 3.2 + 98.10 + 1163.3 + (- 10) = 24.17 + 54.42 + 925 + W W = 251.01 Btu / lbm Steam Flow = 100 Hp (2544 Btu/hr /Hp) / 251.01 Btu/lbm = 1014 lbm/hr
  • 58.
    OCM Thermodynamics General Engineering 1. Steamenters a turbine with an enthalpy of 1292 Btu/lb and leaves with an enthalpy of 1098 Btu/lb. The transferred heat is 13 Btu/lb. What is the Work in Btu/min and in Hp for a flow of 2 lb/sec. Ans. 512.3 Hp 2. It could be (1292-1098)-13 *2 = 362 BTU/sec ->21720 BTU/min 2. A thermodynamic steady flow system receives 4.56 kg/min of fluid (mass flow rate) where p1 = 137.9 kPa, ν1 = 0.0388 m 3/kg, v1 = 122 m/sec and U1 = 17.16 kJoules/kg. The fluid leaves the system at a boundary where p2 = 551.6 kPa, ν2 = 0.193 m 3/kg, v2 = 183 m/sec and U2 = 52.8 kJoules/kg. During passage through the system, the fluid leaves 3,000 Joules/sec of Heat. Determine the Work. Ans. W = - 486 kJoules / min
  • 60.
    OCM Thermodynamics General Engineering  Itis the quantity of heat required to change the temperature of unit mass through one degree.  Ration of specific heats k = cp/cv > 1
  • 61.
    OCM Thermodynamics General Engineering  Basedon Joule’s Law, ΔU = mcv (T2 – T1) whether the volume remains constant or not.
  • 62.
    OCM Thermodynamics General Engineering  Basedon Joule’s Law, ΔH = mcp (T2 – T1) whether the pressure remains constant or not.
  • 63.
    OCM Thermodynamics General Engineering  H= U + pV  pV = RT  cp dT = cv dT + R dT  cp = cv + R  cv = R/ k – 1  cp =kR/ k - 1
  • 64.
    Learning Plan –Module 1 Week 5 – 6 Sept 30 and Oct 7 • Preliminary Examination – Oct 7 W • Lesson 3 - Ideal Gas
  • 65.
  • 66.
    OCM Thermodynamics General Engineering  Vaporphase of a substance when it is above the critical temperature  Has a single defined thermodynamic state at room temperature  A gas that is not far from the state of condensation  Mixture of two phases at room temperature
  • 67.
  • 68.
    OCM Thermodynamics General Engineering Simply becauseit conforms to the simple perfect gas laws!
  • 69.
    OCM Thermodynamics General Engineering  Air Nitrogen  Oxygen  Hydrogen  Helium  Argon  Neon  Krypton  Heavier gases (carbon dioxide)
  • 70.
    OCM Thermodynamics General Engineering  Anyequation that relates the pressure, temperature and specific volume of a substance.
  • 71.
  • 72.
    OCM Thermodynamics General Engineering  Itis different for each gas.  R = Ru/M where: Ru = Universal gas constant M = Molar mass/mol. Weight
  • 73.
    OCM Thermodynamics General Engineering  Samefor all substances  Ru Values: 8.314 kJ/kMol.K 8.314 kPa.m3/kmol.K 0.08314 bar.m3/kmol.K 1.986 Btu/lbmol.R 10.73 psia.ft3/lbmol.R 1545 ft.lbf/lbmol.R
  • 74.
    OCM Thermodynamics General Engineering  Massof one mole, also called as gram-mole (gmol), of a substance in grams  m = MN where: m = mass of system M = molar mass N = mole number
  • 75.
    OCM Thermodynamics General Engineering 1. Determinethe mass of the air in a room whose dimensions are 4m x 5m x 6m at 100 kPa and 25 degC. Gas constant of air is 0.287 kPa.m3/kg.K.
  • 76.
    OCM Thermodynamics General Engineering 2. Thevolume of a 7 x 13 ft tank is 543.3 cu.ft. It contains air at 180 psig and 75 degF. How many 1 cu.ft. drums can be filled to 60 psig and 70 degF if its assumed that the air temperature in the tank remains at 75 degF. The drums have been sitting around in the atmosphere which is at 14.7 psia and 70 degF.
  • 77.
    OCM Thermodynamics General Engineering 3. Twovessels X and Y of different sizes are connected by a pipe with a valve. Vessel X contains 164 L of air at 3246.87 kPa, 90 degC. Vessel Y, of unknown volume, contains air at 70.5 kPa, 5.6 degC. The valve is opened and when the properties have been determined, it is found that pm = 1500 kPa, tm = 40.5 degC. What is the volume of vessel B?
  • 78.
    OCM Thermodynamics General Engineering  Degreeof disorder or randomness in the system.  It is the property of a substance which remains constant if no heat enters or leaves the substance, while it does work or alters its volume, but which increases or diminishes a small amount of heat enter or leave. ΔS = mc ln(T2/T1)
  • 79.
    OCM Thermodynamics General Engineering 4. Fora certain ideal gas R = 25.8 ft.lb/lb.R and k = 1.09, a) What are the values of cp and cv ? b) What mass of this gas would occupy a volume of 15 cu.ft at 75 psia and 80 F? c) If 30 BTU are transferred to this gas at constant volume in (b), what are the resulting temperature and pressure?
  • 80.
    OCM Thermodynamics General Engineering 5. Thespecific heat of superheated steam at approximately 150 kPa can be determined by the equation What is the enthalpy change between 300 ºC and 700 ºC for 3 kg of steam? Compare with the steam table (2565 kJ).
  • 81.
    OCM Thermodynamics General Engineering 6. A10 ft3 tank contains gas at a pressure of 500 psia, temperature of 85 degF and a weight of 25 pounds. A part of the gas was discharged and the temperature and pressure changed to 70 degF and 300 psia, respectively. Heat was applied and the temperature was back to 85 degF. Find the final weight, volume and pressure of the gas.
  • 82.
    OCM Thermodynamics General Engineering 7. Amotorist equips his automobile tires with a relief-type valve so that the pressure inside the tire will never willexceed 240 kPa (gage). He starts a trip with a pressure of 200 kPa (gage) and a temperature of 23 degC in the tires.During the long drive, the temperature of the air in the tires reaches 83 degC. Each tire contains 0.11 kg of air. Determine (a) the mass of air escaping each tire, (b) the pressure of the tire when the temperature returns to 23degree Celsius. Use R = 287.08 N.m/kg.K
  • 83.
    OCM Thermodynamics General Engineering 8. Anautomobile tire contains 3730 cu in. of air at 32 psig and 80 degF. R = 53.342 lb.ft/lb.R (a) What mass of air is in the tire? (b) In operation, the air temperature increases to 145 degF. If the tire is inflexible, what is the resulting percentage increase in gage pressure? (c) What mass of the 145 degF air must be bled off to reduce the pressure back to its original value?
  • 84.
    OCM Thermodynamics General Engineering Guidelines:  WithFront Page  Margin: 1x1x1x1 (Visible)  Engineering Lettering  Problem Statement and Solution  Box your final answers and round off up to two (2) decimal places.  CHAPTER 3: REVIEW PROBLEM No. 6 (A 6 m3 tank…) and No. 8 (A spherical balloon..)