ME 414 FluidThermal System Design

1
ME 414 Fluid-Thermal System Design

• Project 1 Design of a Lawn Sprinkler System
• Jeremy Manning
• Kyle Powell
• Patrick Richardson
• Spring 2004

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Requirements/Penalty Functions

• Ground must be watered equally
• Minimum amount of water outside yard
• Minimum time to deliver an inch of water
• Minimum capital cost
• Minimum electric utility cost

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About Lawn Sprinkler Systems

• 100 overlap of watered areas is required
• Head to Head Coverage

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About Lawn Sprinkler Systems

• Professional irrigation system installers
• have to perform a balancing act between
• system performance and practicality
• A large number of small sprinklers can perform
  very well, but require more of the yard to be dug
  up, and homeowners do not like stepping on a
  multitude of sprinkler heads
• This design forfeits some cost savings in favor
  of practicality, especially in the large back
  yard area

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Sprinkler Layout Spray Pattern
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Sprinkler Layout Type of Rainbird Sprinklers
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Pipe Layout
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Fathom
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Fathom

• Software that models fluid systems
• Calculates pressure drops, fluid velocities,
• head, flow rates

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Discharge Coefficient

• A function of Reynolds number, diameter ratio and
  system geometry
• Facilitates loss calculation, making the design
  more realistic
• Corrects the theoretical flow equation for the
  effects of velocity profile
• Assumes constant water temp. and therefore
  constant viscosity

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Discharge Coefficient

• Coefficients were calculated by using flow rates
  and pipe areas to find velocities and Reynolds
  numbers
• Results are very close to previously determined
  experimental quantities

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Comparison

• International Organization
  Our Data
• of Standards Data (ISO 5167-1)

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Pump SelectionA pump was selected that
operates near its peak efficiency at our systems
operating level of 190 GPM and 320 ft. of
headThe pump is manufactured by American-Marsh
Pumps, Model 380_MultHSC 2.5x3
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Time to Deliver 1 of Water

• The front yard and side yard will get an inch of
  water in 37 minutes
• The back yard has larger sprinklers with lower
  flow rates
• It will take1 hour, 23 minutes, and 20 seconds to
  deliver an inch of water to the backyard

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Amount of Water Wasted

• Six of the large 17.5 foot radius sprinklers
  spray some water off property, area of over spray
  is shown in red
• 544.05 square feet outside the yard are
  watered
• 54.02 gallons of water fall outside the yard
  in the time it takes to deliver an inch or water

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Capital Cost

• Sprinkler cost 322.70
• Pipe cost 490.42
• Pump cost 600.00
• Valves and fittings 161.13
• Total 1574.25

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Electric Utility Cost

• At current electricity utility rates, it will
  cost 1.68 for every hour that the pump is run
• To run the pump for the amount of time required
  to deliver an inch of water to the entire yard
  will cost 2.32

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What Would We Do Differently

• Move the largest sprinkler heads toward the
  middle of the yard to reduce wasted water
• Determine a was decrease utility cost
• Change Pressure Drop
• Always a TRADE OFF

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Project 2 Design of a Large Automotive Heat
Exchanger
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Task

• Design a shell and tube heat exchanger that will
  provide cooling for four 600 HP diesel engines.
• The four engines are being tested by being run
  for 1000 hours continuously.
• The engines are stationary and in close proximity
  to one another

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Goal

• The goal of this project is find the best
  possible balance between the critical parameters
• Weight Minimize
• Shell side pressure drop - Minimize
• Tube side pressure drop - Minimize
• Total heat transfer 1.2 Megawatts
• There is Always a Tradeoff Between These
  Parameters!

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Known Quantities Tube Side

• The tube side of the heat exchanger will contain
  the flow of engine coolant from the four engines.
• The engine coolant is a 50/50 mixture of water
  and ethylene glycol.
• The flow rate is 80 gallons per minute.
• The inlet temperature is 235 Fahrenheit.
• The outlet temperature is 210 Fahrenheit.

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Known Quantities Shell Side

• The shell side fluid is treated water from a
  nearby lake.
• The inlet temperature is 65 Fahrenheit.

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Heat Distribution and Start-up

• Only one third of the heat generated by the four
  engines is delivered to the engine coolant.
• The rest of the heat is transformed into work or
  sent out of the exhaust system.
• The system needs to reach steady-state conditions
  quickly, so the heat exchanger needs to be
  slightly oversized.

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Design Tools

• MATLAB
• Facilitated calculations
• A Design of Experiments (D.O.E) was used to vary
  parameters and do multiple experimental runs
  simultaneously
• MINITAB
• Statistical Software
• Data is imported from Matlab
• A tool to define Critical Parameters
• Used to optimize the Critical Parameters

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Choosing Critical Variables

• The Matlab DOE script file allowed us to vary
  several system variables at a time, and run all
  possible combinations of these properties at the
  same time
• For example, we could choose five variables,
  assign each of them two possible values, and then
  run all 32 possible combinations of them

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Choosing Critical Variables

• Changing the value of many variables at the same
  time allowed us to find which variables had the
  greatest effect on the systems pressure drops,
  weight, and total heat exchange

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Funneling of Variables
There are 41 variables in the heat exchanger
system Funneling is the process of whittling
this number down and finding the variables that
have the largest effect on the system
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Choosing Critical Variables

• On the first set of variable changes, we found
  that of tube passes is not a critical variable.
• This variable only affected tube side pressure
  drop
• From there on, of tube passes was set at 1.

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Choosing Critical Variables

• In this manner, Minitab allowed us to eliminate
  many system variables, including
• tube layout angle, baffle spacing, baffle cut,
  tube pitch, and shell thickness

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Choosing Critical Variables

• An Interaction Plot was also used for each of
  the variables.
• An Interaction Plot shows the relationship
  between each variable and how it relates to each
  of the critical parameter
• These relationships helped tremendously when
  optimizing the design.

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Choosing Critical Variables

• This funneling process led us to choose
• the following as the most important
  variables
• Shell inside diameter
• Tube length
• Tube diameter
• Shell side mass flow rate

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Optimization

• Using the Response Optimization in Minitab, we
  could optimize our design.
• The two designs on the right used different
  variable ranges.
• Our optimized design is the top chart

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Final Design

• Optimized Values
• Tube OD 12.7mm
• Tube Thickness - .889mm
• Shell ID - .3048m
• Shell side mass flow rate 15 kg/s
• Tube Length 4m

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Critical Parameters of Final Design

• Shell Side Pressure Drop 165 KPa
• Tube Side Pressure Drop 1.8 KPa
• Weight 629 kg.
• Heat Transfer Rate 1.27 KW

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Critical Parameters of Final Design

• The most important consideration of this design
  was the heat transfer ratio
• This is the ratio between the desired and actual
  heat transfers
• Heat exchanger must be slightly oversized so it
  can reach operating temperature quickly
• Heat Transfer Ratio 0.94

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References

• www.sprinklerwarehouse.com
• www.rainbird.com
• www.irrigationtutorials.com
• www.mcmaster.com
• www.greatlakeslandscaping.net
• http//web.ask.com
• http//www.mathsdirect.co.uk/pure/purtuttrirad.htm
  
• http//www.lmnoeng.com/nozzles.htm
• www.pumpflo.com
• Grainger Catalog CD-ROM
• Fundamentals of Fluid Mechanics
• Schetz and Fuhs, John Wiley and Sons
  Publishing
• International Organization of Standards (ISO
  5167-1).
• http//www.cummins.com/na/pages/en/products/trucks
  /isx.cfm
•