1. Kenneth M. Klemow, Ph.D. Wilkes University Prepared for BIO/EES 105 Energy in our World II. Concepts relating to heat

2.  Property of all systems  Based on kinetic energy of molecules ◦ Heat is TOTAL energy of all molecules in a system  Typically measured in Calories or BTUs ◦ Temperature is AVERAGE energy of all molecules in a system  Typically measured in degrees  Property of all systems  Based on kinetic energy of molecules ◦ Heat is TOTAL energy of all molecules in a system  Typically measured in Calories or BTUs ◦ Temperature is AVERAGE energy of all molecules in a system  Typically measured in degrees FahrenheitCelsiusKelvin Water freezes320273 Water boils212100373 Human body98.637310

3.  Within a system ◦ Increase in heat causes increase in temperature ◦ Governed by equation  Within a system ◦ Increase in heat causes increase in temperature ◦ Governed by equation http://www.thekitchn.com/thursday-giveaway-instantread-56533 Q = mc(  T) Where: Q – heat (cal., BTU) M – mass C – specific heat  T – change in temp. Q = mc(  T) Where: Q – heat (cal., BTU) M – mass C – specific heat  T – change in temp.

4.  Between systems ◦ Not related ◦ One system can have higher heat yet lower temperature  Between systems ◦ Not related ◦ One system can have higher heat yet lower temperature

5.  Heat can move from one system to another ◦ Only when there is a temperature difference ◦ Move from higher temperature to lower temperature object.  Heat can move from one system to another ◦ Only when there is a temperature difference ◦ Move from higher temperature to lower temperature object. http://www.ces.fau.edu/nasa/

6. http://www.grc.nasa.gov/WWW/Wright/airplane/heat.html

7.  Measure of change in temperature as a result of heat absorbed. ◦ Metric system: # joules needed to raise 1 kg of material by 1 o C. ◦ English system: # BTUs needed to raise 1 lb of material by 1 o F.  Measure of change in temperature as a result of heat absorbed. ◦ Metric system: # joules needed to raise 1 kg of material by 1 o C. ◦ English system: # BTUs needed to raise 1 lb of material by 1 o F. http://addheat.wordpress.com/2011/03/24/

9. Vaporization liquid gas For water: 540 kcal / kg Vaporization liquid gas For water: 540 kcal / kg Fusion solid liquid For water: 80 kcal / kg Fusion solid liquid For water: 80 kcal / kg http://blogs.yis.ac.jp/19miyoshiay/ http://ww.abc6.com/story/

10.  Heat absorbed or released depending on direction  Important in heat balance at earth’s surface, regulating temperatures of organisms  Heat absorbed or released depending on direction  Important in heat balance at earth’s surface, regulating temperatures of organisms

13.  Energy of molecules directly transferred to adjoining molecules ◦ Causes them to gain heat  Energy of molecules directly transferred to adjoining molecules ◦ Causes them to gain heat http://www.physicstutorials.org/

14. High in metals High in metals Intermediate in brick Low in styrofoam These make good insulators

16.  Occurs in liquids and gases  Warm liquid / gas becomes less dense and rises through medium ◦ Creates eddy currents ◦ Carries much energy  Occurs in liquids and gases  Warm liquid / gas becomes less dense and rises through medium ◦ Creates eddy currents ◦ Carries much energy

17.  Involves electromagnetic waves  Produced by charged particles  Travel at speed of light  Wave components include: ◦ Amplitude ◦ Frequency ◦ Wavelength  Electric and magnetic waves are perpendicular to field of travel

18.  Velocity (m/s) = wavelength (m) x frequency (#/second)  As wavelength increases, frequency decreases  Velocity (m/s) = wavelength (m) x frequency (#/second)  As wavelength increases, frequency decreases

19. More energy Less energy

20.  When radiation strikes a body, it causes that body to start radiating, itself. ◦ Will the wavelengths of that energy likely to be longer or shorter than the energy striking it? ◦ When sunlight hits the earth, will the re-radiated energy be more likely to be in the form of:  Ultraviolet, Visible, Infrared energy ◦ When light strikes a chlorophyll solution, some of the energy is reradiated as visible light. What is the most likely color for that light?  Blue, Green, or Red  When radiation strikes a body, it causes that body to start radiating, itself. ◦ Will the wavelengths of that energy likely to be longer or shorter than the energy striking it? ◦ When sunlight hits the earth, will the re-radiated energy be more likely to be in the form of:  Ultraviolet, Visible, Infrared energy ◦ When light strikes a chlorophyll solution, some of the energy is reradiated as visible light. What is the most likely color for that light?  Blue, Green, or Red

21.  Conduction, convection and radiation all occur in windless environment. ◦ Convection sets up eddies of moving air  Adding wind can rapidly remove energy by mass transfer.  Objects often covered by boundary layer of still air ◦ Conduction and convection predominate  Increasing wind speed causes boundary layer to become thinner. ◦ Transfer of energy greater when wind increases  Conduction, convection and radiation all occur in windless environment. ◦ Convection sets up eddies of moving air  Adding wind can rapidly remove energy by mass transfer.  Objects often covered by boundary layer of still air ◦ Conduction and convection predominate  Increasing wind speed causes boundary layer to become thinner. ◦ Transfer of energy greater when wind increases

22.  Indoor environments often more comfortable than outdoor. ◦ Stay dry ◦ Regulate light ◦ Regulate temperature  People prefer temperatures between 65-75 o F ◦ When T<65, we heat ◦ When T>75, we cool  Indoor environments often more comfortable than outdoor. ◦ Stay dry ◦ Regulate light ◦ Regulate temperature  People prefer temperatures between 65-75 o F ◦ When T<65, we heat ◦ When T>75, we cool

23.  When cold we add heat via radiators, fireplaces, space heaters  Heat generators warm the air via radiant energy  If air carried away, need to warm the new air. ◦ Energy needed = 0.018 BTU / ft 3 / o F  When cold we add heat via radiators, fireplaces, space heaters  Heat generators warm the air via radiant energy  If air carried away, need to warm the new air. ◦ Energy needed = 0.018 BTU / ft 3 / o F

24.  Imagine you come upon a small, uninhabited, single-roomed cabin in the winter ◦ Height = 10’ ◦ Width = 20’ ◦ Length = 20’  It’s 15 o F outside, you want to heat it to 65 o F.  How many BTUs will it take?  Imagine you come upon a small, uninhabited, single-roomed cabin in the winter ◦ Height = 10’ ◦ Width = 20’ ◦ Length = 20’  It’s 15 o F outside, you want to heat it to 65 o F.  How many BTUs will it take?

25.  If energy costs $30.00 / million BTUs, how much will initially heating the cabin cost?

26.  Heat losses due to conduction through the walls.  Heat losses due to infiltration of cold air.  Heat losses due to conduction through the walls.  Heat losses due to infiltration of cold air.

27.  Building has four walls, a ceiling, and a floor ◦ Heat will be lost through each ◦ Go back to formula Q/t = (k x A x  T)   k = thermal conductivity of wall / floor / ceiling   = thickness  For building material, we don’t consider thermal conductivity, per se.  Instead we express as thermal resistance (R value), where R =  /k. ◦ Units = ft 2 -hr- o F/Btu  Building has four walls, a ceiling, and a floor ◦ Heat will be lost through each ◦ Go back to formula Q/t = (k x A x  T)   k = thermal conductivity of wall / floor / ceiling   = thickness  For building material, we don’t consider thermal conductivity, per se.  Instead we express as thermal resistance (R value), where R =  /k. ◦ Units = ft 2 -hr- o F/Btu

28. MaterialThicknessR value Plywood0.5”0.62 Fiberglass insulation 3.5”10.9 Hardwood floor 0.75”0.68 Asphalt shingle ----0.21 Wood siding0.50.81

29.  Remember R =  /k ◦ So 1/R = k/   Remember Q/t = (k x A x  T)  ◦ So Q/t = k/  (A x  T) ◦ And then 1/R (A x  T) ◦ And then Q = 1/R (A x  T x t)  Remember R =  /k ◦ So 1/R = k/   Remember Q/t = (k x A x  T)  ◦ So Q/t = k/  (A x  T) ◦ And then 1/R (A x  T) ◦ And then Q = 1/R (A x  T x t) Q = 1/R (A x  T x t) http://www.kfiam640.com/

30.  How much energy (in BTU) is lost through a wall measuring 20’ x 10’ in an hour.  Assume: ◦ Wall covered by 0.5” plywood ◦ It’s 65 o F inside and 15 o F outside  How much energy is lost over the course of 24 hours?  How much energy (in BTU) is lost through a wall measuring 20’ x 10’ in an hour.  Assume: ◦ Wall covered by 0.5” plywood ◦ It’s 65 o F inside and 15 o F outside  How much energy is lost over the course of 24 hours?

31.  How much energy (in BTU) is lost from the entire house by conduction in an hour? ◦ Hint 1: Calculate loss through the four walls ◦ Hint 2: Calculate loss through the ceiling ◦ Hint 3: Calculate loss through the floor ◦ Hint 4: Add together  Then calculate loss from the house in a 24 hour day.  How much energy (in BTU) is lost from the entire house by conduction in an hour? ◦ Hint 1: Calculate loss through the four walls ◦ Hint 2: Calculate loss through the ceiling ◦ Hint 3: Calculate loss through the floor ◦ Hint 4: Add together  Then calculate loss from the house in a 24 hour day.

32.  What is daily cost to heat house if energy = $30.00 / million BTUs?  What would be the monthly cost?  What is daily cost to heat house if energy = $30.00 / million BTUs?  What would be the monthly cost?

33.  Go back to case of wall. How much heat was lost in an hour when wall was 0.5” plywood?  Now suppose that your wall was composed of 3.5” of fiberglass insulation. ◦ Hint 1: Find R value for 3.5” of fiberglass ◦ Hint 2: Recalculate based on that value. ◦ Express the difference here____________  If wall was 0.5” plywood AND 3.5” insulation, add the two R values together. ◦ Then recalculate  Go back to case of wall. How much heat was lost in an hour when wall was 0.5” plywood?  Now suppose that your wall was composed of 3.5” of fiberglass insulation. ◦ Hint 1: Find R value for 3.5” of fiberglass ◦ Hint 2: Recalculate based on that value. ◦ Express the difference here____________  If wall was 0.5” plywood AND 3.5” insulation, add the two R values together. ◦ Then recalculate

34.  What would be hourly loss if all four walls were covered by 3.5” insulation?  What would be hourly loss if ceiling was covered by asphalt shingle above plywood?  What would be hourly loss if floor covered by 0.75” hardwood floor?  Next calculate over course of a day  Next calculate over course of a month  What would be hourly loss if all four walls were covered by 3.5” insulation?  What would be hourly loss if ceiling was covered by asphalt shingle above plywood?  What would be hourly loss if floor covered by 0.75” hardwood floor?  Next calculate over course of a day  Next calculate over course of a month

35.  Premise ◦ Houses leak warm air, and allow cold air to enter ◦ That air needs to be warmed up. ◦ Formula for calculating this:  Premise ◦ Houses leak warm air, and allow cold air to enter ◦ That air needs to be warmed up. ◦ Formula for calculating this: Q infil = 0.018 x V x K  T x t

36.  What would be energy loss in an hour, if all of the air is exchanged over the course of an hour?  How much energy would be lost over the course of 24 hours?  How much energy would be lost if the house leaked air at 1/10 the rate?  What would be energy loss in an hour, if all of the air is exchanged over the course of an hour?  How much energy would be lost over the course of 24 hours?  How much energy would be lost if the house leaked air at 1/10 the rate?

37.  Basis for home energy audit!

38.  Renewable vs nonrenewable  Traditional vs new energy  Commercialized vs non-commercialized  Centralized vs distributed generation  On-grid vs off-grid  Renewable vs nonrenewable  Traditional vs new energy  Commercialized vs non-commercialized  Centralized vs distributed generation  On-grid vs off-grid

39.  Primary energy is the energy as it is available in the natural environment, i.e. the primary source of energy.  Secondary energy is the energy ready for transport or transmission.  Final energy is the energy which the consumer buys or receives.  Useful energy is the energy which is an input in an end-use application.  Primary energy is the energy as it is available in the natural environment, i.e. the primary source of energy.  Secondary energy is the energy ready for transport or transmission.  Final energy is the energy which the consumer buys or receives.  Useful energy is the energy which is an input in an end-use application.

40. energytechnologyexamples Primary coal, wood, hydro, dung, oil Conversion power plant, kiln, refinery, digester Secondary refined oil, electricity, biogas Transport/ transmission trucks, pipes, wires Final diesel oil, charcoal, electricity, biogas Conversion motors, heaters, stoves Useful shaft power, heat

41. CO 2 H2OH2O C 6 H 12 O 6 Carbon reduction Energy Carbon oxidation

42. Energy Stored Energy consumed Energy Respired

44. Energy lost at each step (usually 90%)