What innovation drove the industrial revolution in the 1800’s?

1. What innovation drove the industrial revolution in the 1800’s?

2. THE STEAM ENGINE

3. A steam engine is an example of a heat engine. In goes heat Qin And the difference is work Out goes less heat Qout Wout

4. Heat engines have been harnessed to do all kinds of work for us.

5. They come in all kinds of designs but basically do the same thing. RX-7 Rotary Engine

6. Ever since they were invented, it was desired to improve their efficiency. To use less coal to do the same job saves $$. Enter Sadi Carnot, a French Engineer early 1800’s

7. Most engineers at the time were looking for ways to tweak designs for better efficiency. Carnot wanted to find the maximum efficiency nature would allow. In the process, he founded the field of THERMODYNAMICS As an engineer he was lousy and never built anything of note, but as a scientist his contributions have long outlasted any designs because developed the fundamental understanding.

8. heat motion Thermodynamics: The study of heat and its transformation into mechanical energy. Most of modern thermodynamics can be understood with a little common sense and an understanding of conservation of energy.

9. 1st off, heat flows from high temperature objects to low temperature objects, until they are at the same temperature. They are now at the same temperature or THERMAL EQUILIBRIUM

10. The 0th law of thermodynamics. If both A and C are in thermal equilibrium with B, then A and C are in thermal equilibrium with each other. B C A This is the common sense bit….

11. Q The 1st law of thermodynamics: (in laymen's terms) When energy is added to a system, it has to be somewhere! Now remember a hot cup of coffee is not going to suddenly shoot up a hill. Even though the atoms have a lot of kinetic energy. This is because the atoms are bouncing around randomly

12. Q The 1st law of thermodynamics: (in laymen's terms) When energy is added to a system, it has to be somewhere! U In this case heat was added and the internal energy of the system increased. The atoms move faster. But the cup of coffee doesn’t take off. Why?

13. Since this is not A ChE class, DU ONLY if there is a change in TEMPERTURE Change in internal energy means change in temperature. DT =0  DU =0

14. What causes the transfer of energy??? Hint: W__ __ __ = D E

15. An expanding piston of gas can do work on a wheel or something. In doing so energy has left the gas. W = F d How does the gas exert a force on the piston? d

16. W = F d F = P A d d W = P (A d) A DV

17. But was work done ON the gas, or did the gas DO work in this case? Did the gas gain or lose energy? W = PDV Let’s not worry about signs just yet.

18. A gas is compressed at a constant pressure (I guess it is was cooled) How much work is done on the gas? W = PDV

19. The work done is equal to the AREA UNDER THE CURVE in a P vs V graph!!!! W = PDV

20. W = PDV If no heat is added to the gas while the piston expands is the pressure of the gas constant?

21. How much work did the gas do on the piston here?

22. The 1st law of thermodynamics can be summed up two ways. The change in energy of a system is equal to how much it gains minus how much it loses! AKA Conservation of Energy OR…… PDV DU = Q + W The equation sheet has Q – W. BUT let’s just use common sense and take the perspective of the gas. Remember Fs = -kx

23. DU = Q + W Find DU, does the temperature increase or decrease? A system gains 50 J of heat and 20 J of work is done on it by compressing it. A system gains 50 J of heat and does 20 J of work while expanding. A system loses 50 J of heat and does 20 J of work while expanding. A system loses 50 J of heat and 20 J of work is done on it by compressing it.

24. Leave some space to add notes Some terms for processes: Isothermal: ___________ doesn’t change Isobaric:_____________ doesn’t change Isochoric:____________ doesn’t change Adiabatic: ___________ does not flow in or out. Q= 0 Temperature Pressure Volume Heat

25. In an adiabatic process, let’s say a piston of air is compressed. What is zero? 0 Is work positive or negative? Adiabatic, Q=0 What does this tell us? PDV + + DU = Q + W It gets hotter, remember the fire syringe?? It happened too quickly for the heat to escape…

26. 1.) Fuel and air in 2.) Compression 3.) Ignition and expansion 4.) Exhaust Diesel engines don’t have spark plugs, how does the fuel ignite?

27. A sample of gas contained in a piston is very well insulated. It is allowed to expand adiabatically. Must lose Internal Energy. (-, Cools) DU = Q + W No heat can come in or out. 0 J Gas does work on surroundings. (-) Try breathing slowly on your hand and the blowing through pursed lips

28. How does doing work on a piston reduce the temperature of an expanding gas? Consider the elastic collision below Gas atom Piston

29. Compressing a gas and doing work on it increases its temperature..

30. Fire syringe demo

31. Air expands and cools forming rain. Dry air forms desert. Warm humid air Pacific Ocean Mojave Desert

32. In an isothermal process, 50 J of heat is added to a gas, what is zero 0 Isothermal, DU=0 Is work positive or negative? What does this tell us? PDV ? + DU = Q + W Heat is added so it must do work (negative work to lose energy)

33. A piston of gas is packed with ice to maintain a temperature of 0oC. As the cylinder is compressed. What happens 0 + - DU = Q + W Q Q

34. In an isochoric process, 50 J of heat is added to a gas, what is zero 0 Isochoric, DV=0 Is work positive or negative? What does this tell us? PDV + + DU = Q + W Heat is added, it can’t do work, so the energy just goes to increasing temperature

35. In an isobaric process, what is zero Isobaric, DP=0 What does this tell us? PDV DU = Q + W Just crunch the numbers. You know P

36. What type of process is this Isochoric, DV=0

37. What type of process is this Isobaric, DP=0

38. In an isothermal change we know that what 2 things about a gas are constant? DU = Q + W Temperature & Internal Energy

39. If the temperature of a gas is constant, then we know based on the ideal gas law…. P V = n R T Constant Ideal Gas Constant Constant assuming that ….

40. In an isothermal change P V = constant The value of a the constant depends on the starting conditions of the gas: Temperature, moles, pressure etc…. Let’s pick a constant and see what a P vs V looks like for it.

41. P V = constant I like easy numbers, Let’s make the starting conditions for everything 1. Here we assume temperature is constant. What direction is heat flow? Pressure Volume

42. Heat is absorbed and more work is done. A gas is allowed to expand isothermally and adiabatically. In which case does it do more work on its surroundings? Isothermal Adiabatic

43. A gas is put through a process that starts and ends at point A. Determine the following for the completed cycle. a.) The change in internal energy. b.) The net work on the gas. c.) The heat flow A

44. Note that for a cyclical process Q = W watch signs Or in the case of a heat engine the net work out is equal to the net heat in. A

45. A gas can be brought from point A to B two ways. AD – gas is compressed near a heat sink to remove heat DB- gas is heated but volume is held constant. Or the gas can be heated isothermally, allowed to expand to cool doing work on it surroundings to keep the temperature down B How much work is done on the gas going from ADB? & Heat flow? Isothermal Isochoric A D Isobaric

46. The 2nd law of thermodynamics. It has to do with things that tend to occur spontaneously, that is naturally without some guided help. Things naturally go from “ordered” states to disordered states unless some WORK is put in. ENTROPY

47. If the cards start sorted by suit, and you shuffle them or throw them in the air. What are the odds they will remain sorted to your liking? It is not a true law that can’t be broken. It is just statistically VERY unlikely for things with a lot of possible states like a container of atoms

48. If an egg is dropped and hits the ground, energy is converted to heat. If that heat energy spontaneously put the egg back together it would not violate the law of conservation of energy. How long would you need to wait for that to happen?

49. The 2nd law of thermodynamics. Heat flows naturally from a hot object to a cold object. Heat will not flow spontaneously from a cold object to a hot one. And it is impossible to have a heat engine with 100% efficiency.

50. How hard is it to convert work to heat with 100% efficiency? Easy rub your hands together. Now do the reverse, get the heat to move your hands back and forth? The randomness of heat makes it hard to corral.