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2 energy and heat Energy 101 fall 2015
This document provides an overview of the key concepts around energy that were covered in a lecture, including: 1. Energy is the ability to do work and is measured in Joules, while power is the rate at which work is done and is measured in Watts. 2. There are different units used to measure energy and power, including Joules, BTUs, Watt-hours, and Kilowatts. 3. Energy exists in different forms, including kinetic energy from motion and potential energy from position or chemical state, and energy is transformed between forms but not created or destroyed. 3. Heat is a special form of energy related to molecular motion, and temperature indicates the average kinetic
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2 energy and heat Energy 101 fall 2015
- 1. Discussion of whatis energy Energy not just oil. gas or solar – not just a commodity Basic phyisical parameter/characteristic Deep connections between energy order and the development of intelligence Physics definitions Work = making a change in the universe Energy = Ability to do work Power = rate at which work is done - speedometer/odometerr analogy Types of energy Units definitions for the above Converting from one unit to another (like distance measurments) No energy is “lost” – wasted energy , like a weed, is energy we have no use for Mention energy quality, more detailed lecture next day A few sample calculations Demos? Heat things to the same temperature and have people touch them – specific heat? Solar hot water Introduce concept of specific energy
- 2. Lecture 1 Concept ofEnergy E-101 - Energy and Sustainability Professor Lonnie Gamble Sustainable Living Department Maharishi University of Management This presentation was prepared on solar powered computers
- 3. “There is inall things … a hidden wholeness.” - Thomas Merton, trappist monk and mystic
- 5. Work, Energy, Power Work:Something that makes a change in the Universe Energy: The ability to do work = Joules Power: The rate at which the work is done = Joules per second (watt)
- 6. The Units ofEnergy and Power Energy: Joule BTU - 1 lb water up one degree F Calorie - 1 kg of water up one degree C Watt-hour = 3600 joules Kilowatt-hour = 1000 watt hours Power: Watts = joules/second Kilowatt = 1000 watts BTU/hour Horsepower - 746 watts
- 7. Energy Units: British ThermalUnit (BTU) BTU is commonly used as for measuring heat energy. A BTU is roughly amount of energy released in striking a match
- 8. Energy Units: Watt-hours Watt hoursare typically used to measure electrical energy. A watt-hour is a pretty small unit - it takes 50 of them to make your toast - a kilowatt-hour is 1000 watt-hours. A typical utility-connected family uses about 1000 kilowatt-hours per month of electrical energy. 1 watt-hour=3.41 btu 1 kilowatt-hour = 3410 btu
- 9. Main Point #1 Energy is the ability to do work, and is absorbed or released when change happens. Some examples: change in pressure, change in temperature, change in voltage, change in chemical concentration change in elevation in a gravitational field. Power is the rate that energy is being produced or consumed In order to do, one must think, in order think, one must be. Therefore, the source of action and change is ultimately being.
- 10. Power Units: Watt =Joule/second Awatt is a pretty small unit - it takes 1000 of them to run your toaster. A kilowatt is 1000 watts. 1 Kilowatt (kW) = 1000 Watts = 1000 joules/sec
- 11. Other Power Units Heat:BTU/Hour =.293 watts Engines, Motors: Horsepower = 746 watts
- 12. Main Point #2 Power is a measure of energy flow, the rate at which energy is produced or consumed. Consciousness flows effortlessly from being to form the universe.
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- 14. Main Point #3 There are two main forms of energy: Kinetic – energy related to movement example: flowing water, wind Potential - energy related to position or state example: ball at the top of a hill Being is pure potentiality. In contrast, the manifest universe is eternally in motion.
- 15. Energy is neithercreated nor destroyed – it eternally changes from one form to another. Curving back on myself I create again and again The unchanging unified field is neither created nor destroyed but gives rise to the cycles of creation, maintenance, and destruction at the surface of life.
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- 17. There is no“wasted”energy – energy doesn’t disappear But energy can loose it’s usefulness Car example
- 19. Enegry and powerananlogy w/car odometer or water tank
- 20. Example - SomeEnergy Transformation Calculations Google calculator and google units converter – Use the form “10.5 cm in inches” Solar hot water system – Krystofiak PV system design Energy Center web site PV watts
- 21. Heat Energy Heat isenergy that comes from molecular motion. Heat is the form of energy that flows from warm to cold objects. Heat flows spontaneously from hot to cold. It takes energy to move heat from cold to hot. Other forms of energy can be converted to heat at 100% efficiency
- 22. Temperature Temperature is whatincreases when energy flows into something and decreases when energy flows out of something Ex: What involves more energy -Heating water from 112 to 212 degrees F - Lowering the temperature of a swimming pool by 1 degree F
- 23. Heat Transfer Conduction -heat flow by direct contact between objects Convection - heat flow by fluid motion Radiation - heat flow by direct transfer through space
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- 25. Heat Loss ThroughWalls Heat Loss in BTU/HR= A* (Tin-Tout)/R Tin-Tout= delta T Outside Temp = 20 deg F Inside Temp = 70 deg F R value = 20
- 26. PSYCHROMETRICS The human sensationof heat and temperature
- 27. Heat Storage, SpecificHeat Specific Heat: energy required to raise 1 lb of material 1 degree F Water = 1 btu/lb per deg F Stone, concrete= .23 btu/lb per deg F Sand = .19 Pine = .6 Gypsum = .26 Copper = .09 Earth Block = .25 600 tons of earth block in the SL center
- 28. What involves moreheat flow: Heating 10 lbs of water from 55 degrees to the boiling point? OR Lowering a 70 degree swimming pool temp to 69 degrees?
- 29. Heat Flow TimeLag Stone, Concrete: 1 inch per hour Desert buildings heating example (Sunspace) Passive cooling example – masonry building
- 30. Heat and PhaseChanges Latent Heat Water as ice at 32 degrees to water as liquid at 32 degrees requires 143 btu/lb Liquid water at 32 degrees to liquid water at 212 requires 180 btu/lb Water as liquid at 212 degrees to water as gas at 212 degrees requires 1040 btu/lb
- 31. Main Point #5 Heatis a special form of energy related to molecular motion that flows from warm to cold objects. Temperature drops when heat flows out of an object, temperature rises when heat flows in to an object. During meditation, the mind naturally flows from greater to lesser activity to the field of least action, being
- 33. End Energy andHeat • Energy Calculation Exercise
- 35. • SAI willbring increasingly cost-competitive systems to market between now and 2015, with benefits accruing from the early SAI years. SAI Cost Reductions
- 36. Most frequently identifiednon-technical barriers to solar energy implementation, listed in order of frequency. High cost (addressed by all SAI activities, including R&D effort) Lack of trained technical personnel, reliable installers, and maintenance services Lack of communication, information dissemination, and consumer awareness Inadequate financing options Lack of appropriate, consistent interconnection standards Inadequate government incentives Lack of equitable and effective net-metering guidelines Inadequate codes and standards Liability issues / insurance requirements Poor public perception of solar system aesthetics Non-Technical Barriers to Solar Commercialization
- 37. “Someday, after wehave mastered the winds, the waves, the tide and gravity, we shall harness for God the energies of love. Then for the second time in the history of the world, man will have discovered fire.” - Teilhard de Chardin
- 38. Specific Heat Demo •Demo 008 • Specific Heat of Lead • This is not for the faint of heart or for those who religiously adhere to OSHA guidelines. Lead has a very low specific heat; this demonstration uses this fact in a dramatic way when the demonstrator dumps hot lead pellets (100°C) onto his or her open hand. • MATERIALS • 25 g of lead shot One large test tube (8 in) Ringstand and clamp Hot plate 500 mL beaker with 300 mL of distilled water. Paper towels for cleanup Tongs for holding hot test tube Insulated gloves to handle the hot hotplate and water • PREPARATION • Place the beaker containing the water on the hot plate and heat to boiling. Place the lead shot in the test tube, clamp the tube in place so that the lead-containing portion dips well into the hot water. • PRESENTATION • This demonstration should follow a discussion of specific heat, the calculation of amounts of heat required to bring about given temperature changes, and a discussion of the magnitudes of the specific heat of various substances. The point to make is that water has an exceptionally high specific heat and that lead metal has a very low specific heat. This demonstration exploits these facts. • Compute the temperature change when 25 g of lead at 100°C as added to 25 g of water at 25°; it should be only 2-3 degrees. Ask the class if they believe the result of these calculations; more specifically, ask if they would be willing to have 25 g of lead at 100°C poured into their open hand (which is mostly water). • With as much drama and flourish as you wish, remove the test tube from the boiling water and pour the hot lead shot into your hand. It will feel quite warm, but not painful. Ask whether anybody would want to repeat this with 25 g of boiling water. Be sure to demand an explanation for the expected negative response. • DISCUSSION • Since the specific heats of water and lead are 4.184 J/g°C and 0.16 J/g°C, respectively, the quantity of heat transfered from the lead to its surroundings will be only around 4% of the amount released by an equal weight of water. • HAZARDS • This works very well with 25 g of lead. Don't try to scale up the demonstration! There is no disposal to speak of. The lead can be recycled for the next class, and the water can be poured down the drain after it cools a bit. • REFERENCES • None for this demonstration that I know of...maybe a book on magic tricks.
- 39. Energy and Sustainability SLE-101 The Concept of Energy and Heat
- 40. Thermal output ofthe sun in a quarter of a second is enough to raise the temperature of all of the water on earth up 100 degrees C https://en.wikipedia.org/wiki/Joule