ENG 1102Design Project - Energy Budgets
Where is the energy going?
What resources am I using?
Agenda
● Review electrical, mechanical, and thermal energy calcs
● Introduce Energy Budgets and Applications● Show an energy budget examples● Begin planning and documenting an energy
budget for your project
Thermodynamics
● Energy may be converted from one type to another
- however -● Energy is conserved (i.e., it cannot be
created or destroyed)
Energy Sources/Resources Electrical – Power from GridChemical – Nat. Gas, Oil, SteamMechanical – Human, Potential
Sinks (Energy Consumers)Electrical – Pumps, Mill, Cooling, Gas CompressionThermal - HeatersMechanical - Drag, Rolling Resistance
Thermodynamics energy balance
BrewerySources SinksElectrical
Electrical
Thermal
Chemical
HPV
Sources
Sinks
HumanThermal
Potential
Potential
Mechanical
Electrical
● Flowing electrons– Metals are conductors because they contain few
loosely bound electrons in their outer shells– Electrons in the outer shells are free to jump
from one atom to the next● 1 Coulomb = 6.24150636 x 1018 electrons
(unit for counting electrons (C))
Reference: Eide, et.al, Engineering Fundamentals and Problem Solving, pg. 349 - 360
Electron Flow is Analogous to the Flow of Water in a pipe.
Flow (gpm)
Pump Valve
Pressure (psi)
Reservoir
Current(amp)
Battery Resistor
Voltage (volt)
Ground
Electron Flow is Analogous to the Flow of Water in a pipe.
No Flow
Pump Closed Valve (max resistance)
Max Pressure
Reservoir
No Current
Battery Open Switch (max resistance)
Max Voltage
Ground
Electron Flow is Analogous to the Flow of Water in a pipe.
Flow (gpm)
Pump Open Valve (full flow, min resistance)
Pressure (psi)
Reservoir
Current(amp)
Battery Closed Switch (min resistance, max flow, "short circuit")
Voltage (volt)
Ground
Terminology● Voltage (Volt, V) = potential difference,
difference in energy per unit charge, measured with a voltmeter
● Current (Amp, A) = flowrate of electrons, charge per unit time (C/s), measured with an ammeter
● Resistance (Ohm, ) = opposition to flow of charge
Electrical Power …(watts)
**
Power Voltage CurrentP V I
* *Energy Voltage Current Time
Batteries are specified in terms of Voltage and Amp-Hours.
How much Energy is in a Battery?
What are the units?
Motor Power
• Examples:– 3 Amps, 12 Volts
P = 36 W
– 50mA, 9.4VP = 470 mW
– What's the Power? What are the units?
• Watt [=] J/sec
(3 )*(12 )(3 / )*(12 / )36 /36
(50 )*(9.4 )470
P iVAmps VoltsC s J CJ sWatt
P iVmA V
P mW
As a Team
The electric motor on a table saw runs on 240V circuit and draws a current of 4.8 amps. How much power does it use?
– in watts (W)?
– in horsepower (hp)?● 1 hp = 746 W
As a Team
The electric motor on a table saw runs on 240V circuit and draws a current of 4.8 amps. How much power does it use?
– in watts (W)?
1152 W
– in horsepower (hp)?● 1 hp = 746 W
1.544hp
Electrical Power …(watts)
* *Energy Voltage Current Time
How is it sold?
Electrical Power …(watts)
* *Energy Voltage Current Time
Approx $.12 per kwatt-hour
Electrical Power
● What is Power (units?)– time rate of work or energy (V-amps, joules/sec
or watts)● How is it calculated
– P = V*I = I2*R = V2/R● How is Electrical Power (or Energy) bought
and sold (units?)– kWhr
Elevation Potential Energy …
* *Energy Mass Gravity Height
* *
EnergyAveragePowerTime
heightAveragePower mass gravityTime
If you are peddling up a hill …
What are the units?
Thermal Power
● Heat to raise temperature of water ● Heat to evaporate water as it is held at high
temps● Other thermal power needed???
• Heat capacity (Cp) of water = 1 Btu/(lbm-deg F)• Latent Heat of evap (Hv) = 1000 Btu/lbm
– When shifting phase (liquid to gas) H = Hv
• Natural gas: – 1000 std ft^3 (scf) = 10^6 Btu– Typical unit of measure: therm=100,000 Btu– Approx cost = $1.05/therm
Reference: Holtsapple, et.al, Foundations of Engineering, pg. 71Felder & Rousseau, Elementary Principles in Chemical Processes pg. 365
Thermal Power H Cp T
Thermal Power Example
• You wish to heat a tank containing 100 lbm of water from 25°F to 50°F.
• How much energy is required (in BTU)? • How many scf of Natural Gas will you need
to purchase?
• - Cp-H2O = 1 Btu/(lbm-°F)
• - 1000 std ft^3 (scf) = 10^6 Btu
H Cp T
25
25 *100
2500 2.5
1( ) * (25 )
BtuH
lbmBtu
E lbmlbm
E Btu scf
H Cp T
BtuH F
lbmF
Thermal Power Example• Mass of Water = 100 lbm of
water• T = 25°F to 50°F = 25°F• How much energy is required
(in BTU)? • How many scf of Natural Gas
will you need to purchase?
• - Cp-H2O = 1 Btu/(lbm-°F)
• - 1000 std ft^3 (scf) = 10^6 Btu
● Lance Armstrong: approx 500W over 1 hr– Approx. 1kW over 1 minute
● Bike Rider Guy/Gal: approx 100-200W over 1 hr– Approx. 400W over 1 minute
Power = Energy/TimeReference: Wilson, et.al, Bicycle Science, pg. 44
Human Power
Resource Budget: Accounting for Materials
● Tracks all inputs and outputs to your process (energy, raw materials, byproducts, products, etc.)
● Estimates energy and materials consumed in process
● Used to estimate annual costs/profits of company
● Used to identify opportunities for process improvement
What is an Energy Budget?
● ????
What is an Energy Budget?
● A means of planning the energy usage of a system
● A means of cost predictions and control● An engineering tool to optimize the efficiency
of any energy using system● A “balance sheet” of energy sources and
sinks
What are the major energy consumers? (Sinks)
Where does the energy come from? (Sources)
Residential Homes and Commercial Buildings
Configuration Diagram Brewery
Where are…
Sources?
Sinks?
Energy Budget - BrewingPurpose(s):
– To estimate the energy cost for one batch of beer● In a spreadsheet, list unit operations and estimate
power requirement for the line and annual cost to operate line.
● Cite references and state your assumptions in your spreadsheet
Energy Budget – Flood Control
Purpose(s): - To estimate the energy cost for pumping station at
“rest,” at full operation and expected annual use- Document assumptions in a spreadsheet that
clearly shows units and calculations● Cite references
Example Energy Budget – Brewery(Flood will be similar, electrical)
Energy Budget – HPV
Purpose(s): - To estimate the HPV speed for a given set of
conditions- Document assumptions in a spreadsheet that
clearly shows units and calculations● Cite references
Material Budget● Purpose(s):
– (Brew) To complete a mass balance on a typical brewing line and calculate the input/output quantities
– (Flood) To determine the amount (and type) of material used in constructing flood control system
– AND…To determine the amount of time necessary to construct your flood control system (will it be ready for next hurricane season?)
● Can be completed in spreadsheet format.● Cite references and state your assumptions
Brewery Mass Balance
16 barrels
?
?
???
??
??
?
?
?
General Process Info – What changes are you planning?
Deliverable 6 - Resource BudgetDue Week 10, Day 1
Summarize your Energy and Material Budgets / Mass Balance findings in a memo
●Discuss … how does this estimate compare with your design criteria?
●Suggest a way to significantly reduce energy usage.
Refer to RFP for your project.