Energy Concepts • Terms, definitions, Units • Differentiate Energy vs. Power • Define ‘energy system’ and preview a ‘lifecycle assessment’ • First and Second laws of Thermodynamics • Calculate Efficiency
Energy Service = HOT WATER (NOTE: this is a BATCH system, NOT a FLOW THROUGH system) Question 3: How can we determine the ENERGY EFFICIENCY of this SYSTEM? - What do we know? - What do we need to know? - How to get the information? - What to do with the information? “Energy System” -- Hot Pot
energy absorbed by water (joule, J) m = mass of water (gram, g) Cp = specific heat, 4.186 j/g-˚C ΔT = change in temperature (˚C) Heat Energy Absorbed by Water (USABLE ENERGY OUT) ELECTRIC ENERGY IN = electricity used by hotpot appliance
MEASURE: Water Temperature, initial (T1 , t = 0 seconds) = ___ Water Temperature, final (T2 , t = ___ seconds) = ___ Energy in Usable Energy out “Energy System” -- Hot Pot Electricity Consumed = _________ watts x seconds
Energy in Usable Energy out Question 4: What unit would we use to describe the POWER consumed by the hotpot? (= POWER IN, at any given point in time) Question 5: What unit would we use to describe the ENERGY consumed by the hotpot? (=TOTAL ENERGY IN) “Energy System” -- Hot Pot
Water Large amount of heat (thermal energy) : T2 T1 = 24.2 T2 = 95.0 m = 800800g Watts = 1270 time = 196 seconds Efficiency = m * Cp * ΔT = = 91 % watts * time (s) “Energy System” – Hot Pot Final Calculations
signal to start (all teams will go at once). Your goal is to move all the packing peanuts as rapidly and efficiently as possible. ➢ When time is up, measure the mass of packing peanuts that makes it to your user. Note the amount of peanuts lost (e.g., on the floor) for each group.
Was any system 100% efficient? If yes, what was done to make it so? 2. Which were the least efficient systems? Why? 3. What contributed to greatest losses? Describe. 4. What happens to the “energy” (as represented by packing peanuts) that is “lost”?
efficiency’ of this energy system? Expands the System Boundary to include the primary resource Efficiency = energy gain in water potential energy in primary resource Efficiency ~ 35% Efficiency ~ 90% coal
Hot Pot, efficiency ~90% Extraction, processing, transportation Natural Gas Coal 91 MJ Extraction, transport, thermal power generation 35 MJ Use 100 MJ efficiency ~35% We know the efficiency of processes used to convert the energy from its original form to the form used by our appliance: 100 MJ Use efficiency ~91%
high Energy Efficiency Ratio(EER) • Shut the window and door tightly. • Each 1℃ you raise the temperature = 6% savings of power consumption. • Set room temperature to 26~28℃ (78.8oF-82.2oF) • Clean the heat exchanger or condenser regularly. • Apply heat-insulated material and sunshade to reduce indoor heat capacity. https://www.taipower.com.tw/en/page.aspx?mid=386 https://2qaayg3yvidcn9imquz625sg-wpengine.netdna- ssl.com/wp-content/uploads/2016/05/ductless-air- conditioner.jpg
cm away from walls. • Move refrigerators away from ovens and heaters. • Keep 20 % space empty inside to let the air circulate easily. • Reduce the number of times you open the refrigerator; each time you do, the compressor must operate 10 min to return to a low-temperature. https://www.taipower.com.tw/en/page.aspx?mid=386 https://www.lg.com/us/images/refrigerators/md05130240/gallery/medium01.jpg
Install high-efficiency LED bulbs with the HF electronic ballasts. • Paint the ceilings and walls in light colors to reflect natural sunlight https://www.taipower.com.tw/en/page.aspx?mid=386 https://target.scene7.com/is/image/Target/GUEST_2415de4b- abc2-4490-9f80-222f61348df9?wid=488&hei=488&fmt=pjpeg
their website: https://www.taipower.com.tw/en/page.aspx?mid=317 https://www.taipower.com.tw/upload/317/2018032816540459 885.pdf you find sections B1 and B2 which suggest how you can avoid using electricity during expensive times of day. This helps avoid over-use by everyone at the same time.