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Week 1 – Engineering Agenda Introductions Why should I care about engineering? Motivation Dimensions and Unit Conversion Examples Ideal Gas Law Conservation of Mass Examples Newtonian Fluids and Viscosity Laminar and Turbulent Flow Friction/Pressure Loss in Pipe Flow. - PowerPoint PPT Presentation

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Week 1 Engineering Agenda Introductions Why should I care about engineering? Motivation Dimensions and Unit Conversion Examples Ideal Gas Law Conservation of Mass Examples Newtonian Fluids and Viscosity Laminar and Turbulent Flow Friction/Pressure Loss in Pipe Flow

Why is engineering important in brewing?1. 2.3.

What Engineering Decisions/Designs are Needed in the Brewing Process?

Some Steps in the Brewing Process Malting Mashing In Mashing Lautering Wort Clarification and Cooling Fermentation Carbonization Pasteurization Packaging

Our Approach Learn the fundamentals, then apply them to brewing

First 8 Weeks Slightly more fundamentalsSecond 6 Weeks Slightly more applicationAlso, plenty of practice for the exam!

A Typical DayMorning Lecture new material, work example problems, discussionsAfternoon Practice, practice, get a beer, practice some more!

General Problem Solving MethodologyIdentify the Type of ProblemPrinciples and EquationsSimplify and Identify Properties NeededGet Properties (Tables, Equations, etc.)Solve for Unknown, CalculationsInterpret ResultsAre the Results Reasonable?What Do they Mean?

Dimension Quantifiable physical entity Primary - Name them Secondary - Calculated from primaryUnit Metric used to measure dimension Base m, kg, s, K, A, mole Derived From base units (J, N, W)Dimensions or Units? The temperature is 37 outside. Increase the psis. This light bulb will save you 2 kW per day.

Unit Conversion Just Multiply by 1.0

Units Example 1What is the power consumed by a 100 Watt light bulb, in horsepower(1 horsepower = 0.746 kW)?

Units Example 2A pressure gauge indicates that the absolute pressure inside of a vessel is 350 psig (or psi gauge). The vessel is rated to 50 bar. Should we run for cover?

Units Example 3A cylindrical tank has a 10 foot diameter and 15 foot height. What volume of fluid will the tank hold in gallons and in hectoliters.

The Ideal Gas Equation

PV = mRTPV = NRuT

R = Ru / M

For a closed system (no mass in or out)

Ideal Gas ExampleA 2 m3 tank is filled to an absolute pressure of 50 bar using an air compressor. After the tank has been filled, its temperature is 75C. After 24 hours, the tank cools to 15C.

a) Determine the mass of air in the tank.b) Determine the pressure in the tank after it has cooled.

Conservation of MassMass entering system - Mass leaving systemMass accumulation in system

Conservation of Mass Example 1500 gallons of beer is initially held in a tank. Beer flows into the tank at a rate of 2.0 gallons per minute (gpm) an it flows out of the tank at 5.0 gallons per minute. Determine:The volume of beer after 45 minutesThe rate of change of the beer volumeThe time elapsed when the tank is empty The total amount of beer that left the tank

13

Can write separate conservation equations for different components of a mixture

Conservation of Mass Example 2Beer with 19% alcohol by weight is mixed with water to create beer with 4.5% alcohol by weight. If the flow rate of 19% alcohol beer is 40 kg/min, what are the flow rates of 4.5% alcohol beer and water, in kg/min and gal/sec? Assume that the density of the beer is 1000 kg/m3

Fluid StaticsP = gh Pressure vs. HeadFluid Statics Example 1Determine the gauge pressure at the bottom of a 5 m deep tank of liquid water when the top is vented to the atmosphere.Fluid Statics Example 2Determine the pressure at the bottom of a 5 m deep tank of air when the top is vented to the atmosphere.

Newtonian Fluids and ViscositySolid

Elastic Returns to original shapePlastic Partially returns to original Fluid Linear velocity profile while force is appliedForceForceySurface Fixedv

How are Fluids Characterized

A substance that continually deforms under an applied shear stress, no matter how small

Density Mass per unit volumeSpecific Gravity Fluid density / water densitySpecific Weight Fluid weight per unit volume

ViscosityCommon language ThicknessScience/Eng language Ability of fluid to resist a force

Newtonian Fluids and Viscosity

Shear - one fluid element sliding faster than another, like deck of cards Newtons Law for viscosityShear stress = dynamic viscosity x shear rateExample Boat airboat moving through water, air, honey

Forceyv

Newtonian Fluids and ViscosityDynamic viscosity (order of magnitude, STP) Air 0.00001 Pa.sWater 0.001 Pa.sOlive Oil 0.1 Pa.sHoney 10 Pa.s

Handling Newtonian FluidsConservation of Mass (Continuity)inout

Handling Newtonian Fluids Example 1

Water (density = 1000 kg/m3) enters a 2.0 diameter pipe at 10 m/s. The pipe then expands to a 6.0 diameter.a. Determine the water velocity at the outlet of the pipe. b. Determine the mass flow rate.c. Determine the volumetric flow rate.

Handling Newtonian Fluids Example 2

At a hop drying facility, air enters a heater through a 1 m2 duct at 10 m/s, 10oC and atmospheric pressure (101 kPa). The air is heated to 60oC at constant pressure before leaving the heater. To ensure that the hops are not damaged during drying, the air must be slowed to 5 m/s before entering the drying bed. R for air = 0.287 kJ/kg.K. Determine:The inlet mass and volume flowrates of airThe cross sectional area of the drying bed

Reynolds NumberLaminar flow - low flow rates, viscous forces most significantTurbulent flow - high flow rates, inertial forces most significant

Re < 2300Laminar2300 < Re < 5000TransitionalRe > 5000Fully Turbulent

Reynolds NumberExampleRecall the previous example:

Water enters a 2.0 diameter pipe at 10 m/s and it exits through a 6 pipe.

Determine if the flow is laminar, transitional or turbulent in the 2.0 and 6.0 pipes. The dynamic viscosity of the water is 0.001 Pa.s.

Entrance Region and Fully Developed Flow

Laminar Flow:

Turbulent Flow:Le

Entrance Region and Fully Developed FlowExampleRecall the previous example:

Water enters a 2.0 diameter pipe at 10 m/s and it exits through a 6 pipe.

Determine the entrance length of the inlet (2.0 diameter) pipe.

Fully Developed Velocity ProfilesIntegrating to get the volumetric flow rate and average velocity, we getLaminar Flow:Turbulent Flow:Determine the maximum velocities of fully developed flow through the 2.0 and 6.0 pipes in our ongoing example.

Friction Losses in Pipes

found on Moody Chart handout

Determine the pressure drops over 20 meters of pipe for the 2.0 and 6.0 pipes in our ongoing example (in in H2O, psi, and kPa).

Reading

IntroductionSingh 1.1, 2, 5, 6, 8, 9, 11, 14, 17, 22

Fluid FlowFrom Week 1, Singh 2.2, 3, 4, 5Week 2, Singh 2.1, 6, 7, 9