1. Status of Core Courses: Biothermodynamics
Christopher M. Saffron
Department of Biosystems and Agricultural Engineering
07/14/14 1 1

2. Introduction to Engineering Thermodynamics
Therme = heat
Dynamis = power
Science about the conversion and transfer of different forms of energy
Energy
Viewed as the ability of systems to cause changes
A system has energy if it has the capacity to do work
To understand energy, you need to understand energy transfer
Energy is in the form of heat if an energy transfer is caused by a temperature difference
Energy is in the form of work if its transfer is caused by a force acting through a distance 2 2

3. Thermodynamics in Engineering Curriculum
Course Description: …learn to apply the first and second laws of thermodynamics. Analysis of closed and open systems. Study of power cycles and refrigeration cycles. Study of gas-vapor mixtures and psychrometry. Analysis of reaction equilibria and phase equilibria.
Prerequisites at MSU:
BE 101. Introduction to Biosystems Engineering
MTH 235. Differential Equations (first-order linear equations, exact equations, introduction to PDEs)
BS Cells and Molecules (energy metabolism, macromolecules, genetics)
Prerequisites at other Universities:
Differential Equations, Multivariable Calculus, Introduction to Bio-engineering 3 3

4. Textbooks MSU Other Universities
Çengel and Boles, “Thermodynamics: An Engineering Approach.” 8th ed. (required)
Haynie, “Biological Thermodynamics.” 2nd ed. (optional)
Other Universities
2 used Çengel and Boles
1 created a custom text through McGraw Hill titled “Thermodynamics for Living Systems”; problems from Çengel and Boles
1 used Moran et al., “Fundamentals of Engineering Thermodynamics,” 7th ed.
1 used Borgnakke and Sonntag, “Fundamentals of Thermodynamics,” 7th ed.
1 used course notes 4 4

5. 5 5

6. Context in BE at MSU BE 351 Thermodynamics for Biological Engineering
BS 161 – Cells and Molecules
MTH Differential Equations
BE Intro to Biosystems Engineering
BE 477 – Food Engineering: Fluids
BE 478 – Food Engineering: Solids
BE 468 – Biomass Conversion Engineering
BE 485/487 – Senior Capstone Design 6 6

7. History and Evolution of the Course at MSU
Focus on power cycles (including jet engines)
Implies coverage of flow-through devices (open systems)
Second law
2000 to 2006
Course title: Environmental Thermodynamics
Syllabus includes closed systems, open systems, cycles and psychrometry
2007 to present
Course title changed to “Thermodynamics for Biological Engineering”
Engineering process focused with biological engineering applications 7 7

8. Other Engineering Thermodynamics Courses
ME 201 Thermodynamics (3 credit hours)
Basic concepts of thermodynamics. Property evaluation of ideal gases and compressible substances. Theory and application of the first and second laws of thermodynamics. Entropy and Carnot efficiency.
CHE 321 Thermodynamics for Chemical Engineering (4 credit hours)
First and second laws. Thermodynamics of flow and energy conversion processes. Properties of single and multi-component systems. Phase equilibria. Chemical equilibria in reacting systems.
ENE 481 Environmental Chemistry: Equilibrium Concepts (3 credit hours)
Chemistry of natural environmental systems and pollutants. Equilibrium concepts and calculations for acid-base, solubility, complexation, redox and phase partitioning reactions and processes. Applications to ecosystem analysis, pollutant fate and transport, and environmental protection. 8 8

9. Teaching Practices ABET Hybrid lecture and active learning
Problem solving identified as weakness
Thermo is critical for advancing problem solving skills
Hybrid lecture and active learning
31 lectures
36 problems solved in class
~50% of class time involves student problem solving
8 in-class quizzes
11 assigned homework problem sets, due about weekly
At least one FE-type problem per homework set
3 in-semester exams and a final exam 9 9

10. Laws of thermodynamics
First law
in any process, the total energy of the universe remains constant, i.e. energy cannot be created or destroyed
Second law
the entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium
energy has quality as well as quantity, a process occurs in the direction of decreasing energy quality
Third law
as temperature approaches absolute zero, the entropy of a system approaches a constant
Zeroth law
if two thermodynamic systems are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room. 10

11. Energy Transfer 88% Heat Work
The form of energy that is transferred between two systems, or a system and its surroundings, by virtue of a temperature difference
An energy interaction is heat only if it takes place because of a temperature difference
Heat is energy in transition, it is recognized only as it crosses the boundary of a system
Work
Energy transfer associated with a force acting through a distance
An energy interaction not caused by a temperature difference between a system and its surroundings
Work per time is power
Whether energy is transferred as heat or work can depend on how the system boundary is selected, e.g.:
Electric oven
Heating element
Electric oven
Heating element
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room. 11

12. Properties of pure substancesv
sat’d liquid
sat’d vapor
sat’d liquid-vapor region
subcooled liquid
superheated vapor
critical point
Properties of pure substances
P, v, T, U, H, S, G, A, Cp, Cv, etc.
Internal energy U
Enthalpy -- conveniently defined combination property H = U + PV
88%
Nuclear energy
Chemical energy * T v
critical point
Latent energy
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.
Atom
subcooled liquid
superheated vapor
Sensible energy
sat’d liquid
sat’d vapor
Molecule
Atom
sat’d liquid-vapor region
Molecule 12
*Adapted from Cengel and Boles 7th ed. Thermodynamics: An Engineering Approach

13. Closed System Energy Balances
Analysis of the human body as a closed system
Humans are really open systems
Chemical reactions occur in cells
Metabolism—sum total of all chemical reactions in cells
Result of burning foods
carbohydrates, proteins, fats
The rate of metabolism in the resting state is called the basal metabolic rate
for an average adult the basal metabolic rate is 72 W
the body dissipates energy to the environment at a rate of 72 W
chemical energy from food is converted to thermal energy at a rate of 72 W
function of activity, e.g. exercise can increase metabolic rate more than 10x
100% P A F ds
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room. 13

14. Open System Energy Balances
88%
Open systems involve mass flow across the system boundaries
Work is required to push the mass into or out of the control volume— this work is flow work CV V P m F
Imaginary piston
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room. 14

15. Open System Energy Balances for Engineering Devices
Nozzles:
Turbines:
Typically involve no work:
Typically no potential energy change:
Large changes in velocity:
Energy balance for nozzles:
Heat transfer is usually negligible:
Potential energy is negligible:
High velocities, but velocity change is low, therefore ΔKE is small compared to ΔH:
Energy balance for turbines:
Compressors and pumps:
Throttling devices:
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.
No change in potential energy:
Outlet velocity is greater than inlet velocity, but kinetic energy change is negligible:
The energy balance reduces to:
Valves are isenthalpic devices
Heat transfer is usually negligible:
Potential energy is negligible:
Velocities are typically low:
Energy balance: 15

16. Open System Energy Balances—Unsteady State
Mass balance:
Energy balance:
Wsh Wb We Q
min
mout
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room. 16

17. Entropy and the Second Law
88%
Energy has quality as well as quantity, and actual processes occur in the direction of decreasing quality
The entropy of an isolated system not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium
Heat cannot spontaneously flow from a material at lower temperature to a material at higher temperature
It is impossible to convert heat completely into work
Clausius Inequality:
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.
Gibbs Equations:

18. Heat Engines, Carnot Cycles, Reversibility
100%
100%
88%
High-temperature source
The Carnot heat engine P 1 QH QH
Heat
engine 2
Wnet,out
Wnet,out
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room. 4 QL 3
Low-temperature sink QL v 18

19. Reciprocating Piston Power Cycles
25%
Isentropic compression
V=const. Heat addition
Isentropic expansion
V=const. Heat rejection 1 2
2-3
air
qin 3 4
qout
4-1
Isentropic compression
P=const. Heat addition
Isentropic expansion
V=const. Heat rejection 1 2
air
qin 3 4
qout
4-1
Otto Cycle:
Diesel Cycle: V P
qout
Isentropic 1 2 3 4
qin P 3
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.
qin
Isentropic 4
qout 2
Isentropic 1 V
TDC
BDC

20. Gas and Vapor Power Cycles
Brayton Cycle:
38%
Rankine Cycle:
38%
Compressor
Turbine
Heat exchanger
Wnet, out 1 3 2 4
qin
qout
qin
Turbine
Boiler
Wturb,out 1 3 2 4
Condenser
qout
Wpump,in
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.
Working fluid = Water
Working fluid = Air
Power plant tour at 2/3 semester

21. Ideal Vapor Compression Refrigeration Cycle
Working fluid = Refrigerant
Warm environment at TH > TL
Cold refrigerated space at TL QH QL
Wnet,in
Condenser
Evaporator
Expansion valve 1 2 3 4
38% T s 1 2 3 4’ QH QL 4
Win
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.

22. Differential Property Relations
25%
Gibbs Equations:
Maxwell Relations:
Property Relations:

23. Air-water Psychrometrics
Saturation line, Φ = 100%
Φ = constant
Absolute humidity, ω
Twb = constant
h = constant
v = constant
Dry-bulb temperature
Human comfort:
75%
Human body can be viewed as a heat engine with food as the energy input
Heat transfer is proportional to the temperature difference between the body and the environment
In cold environments, the body will lose more heat because of a larger T difference
In response to cold T, the body reduces blood flow near the surface of the skin
In hot environments, improving heat dissipation is necessary
During light exercise, about half of the rejected body heat is dissipated through perspiration as latent heat, and half is dissipated through convection or radiation as sensible heat
When resting, ~70% of heat is dissipated as sensible heat
When vigorously exercising ~60% of heat is dissipated as latent heat
Human comfort primarily depends upon the dry-bulb temperature, the relative humidity, and the air motion
Most people feel comfortable between 22 and 27°C
Relative humidity between 40 and 60% (higher relative humidity impedes heat rejection by evaporation)
Air velocities of about 15 m/min (high air velocities displace the moist air immediately surrounding the body, and therefore increase heat rejection)
Absolute humidity, ω
humidifying
De-
Dry-bulb temperature
Humidifying
Heating and humidifying
Cooling and dehumidifying
Heating
Cooling
Second law example. A hot cup of coffee cools to ambient temperature, the high temperature energy is transferred to the environment as energy that is not as useful, and of therefore lower quality. Conversely, a cool cup of coffee will not heat itself in the same the same room.

24. Chemical Reactions 75% Combustion Chamber Fuel CO2 HOH N2 Air
hc = Hprod – Hreact
Sensible energy 24 24

25. Chemical and Phase Equilibrium1
vapor
vapor and liquid
liquid
Criteria for chemical equilibria at a fixed T and P
100% reactants
Equilibrium composition
Violation of the 2nd law
50%
63%
Henry’s Law:
Raoult’s Law:
100% products 25 25

26. Other topics Non-ideal gas behavior 25% Exergy analysis 25%
Energy flow in ecosystems 38%
Thermodynamics of cell metabolism 25%
Atmospheric thermodynamics and climate change
Hydrogen, solid oxide and microbial fuel cells
Acid-base chemistry, thermochemistry (esp. combustion)
Osmosis
Chemical kinetics
Fluid mechanics
Human systems
Mass balances 26 26

27. Survey Slide 27 27

28. Student Feedback
Generally, BE Thermodynamics courses are well received
MSU feedback states “…don’t go any faster”
More biological applications desired by students
More biomedical engineering thermodynamics
Metabolic engineering
Pharmacodynamics
Thermodynamics of cell metabolism 28 28

29. In summary, the need for Biological Engineering Thermo…
Traditional ME and CHE thermodynamics don’t cover biological applications
Limited to no refrigeration
Limited to no psychrometry
Focus on industrial chemicals in CHE thermo
Non-ideal aqueous solutions is standard in biology
Discipline relevant topics to consider
Energy capture by plants
Microbial metabolism
Humans as heat engines
Energy flow in ecosystems 29 29

30. Thank you! 30 30