BREWING ENGINEERING part 1

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OBJECTIVES FOR PART 1:

• FLUIDS• FLUID PHYSICAL PROPERTIES• FLUID FLOW• PIPING• PUMPS- 1

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OBJECTIVES:

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FLUID

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Types of substances that can be

classified as fluids include• Liquids

• Gases

• Plasmas

FLUID

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LIQUID

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LIQUID

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GAS

Properties that are characteristic of gases include:

• Able to flow

• Assumes the shape of the container in which

stored

• Distributes pressure evenly within container

• Compressible

• Volume depends on temperature

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The most important fluids in brewing are liquids and gasses

The most important liquids are generally water based:

• Hot/cold liquor for mashing

• Wort

• Beer

• Cleaning solutions

The most important gases are

• Carbon dioxide

• Saturated steam (as a heating source)

• Compressed air (used to actuate valves, pumps, etc.)

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Fluids are physical things and they have

some physical properties that are common

to many substances:• Melting point

• Freezing point

• Boiling point

Other physical properties:• Density

• Specific Gravity

• Viscosity

• Heat Capacity

• Surface Tension

• Thermal Expansion coefficient

• Thermal conductivity

FLUID PHYSICAL PROPERTIES

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DENSITY

Density defined: the mass of a material that fills a

particular amount of space

= Mass per unit Volume

EX- pounds/gallons

or kg/liter

10kg/L 5kg/L

* The density of gasses is highly temperature

dependent.

* The density of liquids is less temperature

dependent.

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DENSITYLets work an example:

• Problem: If you have a completely filled 5

gallon bucket of water, and the mass of

the water contained in the bucket is

precisely measured to be 41.7 lbs, what

is the density of the water.

• Solution:

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SPECIFIC GRAVITY

Specific Gravity (SG) defined: the ratio of the density

of a substance relative to the density of PURE water.

SG (pure water) = 1.0

Can measure dissolved substances in water:

A solution of water + dissolved substance will

have a higher SG. Ex- 1.10

- Fermentable sugars in wort

- Alcohol in finished beer

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SPECIFIC GRAVITY

Hydrometers are tools used to measure the specific gravity of a

liquid

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SPECIFIC GRAVITY

Hydrometers

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SPECIFIC GRAVITY

Lets work an example:

• Problem: If the specific gravity of beer is 1.012, what is

the mass of beer contained in a completely filled beer

barrel (31 gallons)?

• Solution:

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VISCOSITY

The viscosity of a fluid is a measure of the resistance of

the fluid to deformation by an applied force or shear

stress

…or THICKNESS of a FLUID

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VISCOSITY

Viscosity is a strong function of temperature, so viscosity data

always includes some reference to the temperature.

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VISCOSITY

Viscosity is a strong function of temperature.

Water

T = cooler

Molecules closer together

Water

T = warmer

Molecules farther apart

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VISCOSITY

Viscosity is also a function of pressure.

Water

P = higher

Molecules (slightly) closer together

Water

P = Lower

Molecules (slightly) farther apart

Pressure Pressure

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VISCOSITY

- -+

+

++

+

Viscosity is also a function of intermolecular forces

Ex- hydrogen bonding

High Intermolecular Forces (e.g Water)

F = higher

Molecules more attracted

μ = higher

Lower Intermolecular Forces (e.g Methane)

F = Lower

Molecules less attracted

μ = lower (slightly)

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VISCOSITY Viscosity is also a function of intermolecular forces

Ex- size of molecules

Smaller Molecules (e.g Water)

SA = Smaller

Less total force between molecules

μ = lower

F

OHH

OHH

F

Larger Molecules (e.g Glucose)

SA = Higher

More total force between molecules

μ = higher

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VISCOSITY Viscosity is also a function of intermolecular forces

Ex- shape of molecules

Fluid Dynamics Lecture 1- P 23

“Sphere-Like” Molecules (e.g Water)

SA = Smaller, Entanglement = lower

Less total interaction during flow

μ = lower

Chain/Spider-Like Molecules (e.g sucrose)

SA = Higher, Entanglement = higher

More total interaction during flow

μ = higher

Flow Flow

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FLUID FLOW

In the brewery we are primarily concerned with “water-like”

fluids flowing through systems of pumps, pipes, hoses,

valves, and nozzles.

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FLUID FLOW

3 TYPES OF FLOW:

1. Laminar Flow

2. Turbulent Flow

3. Transition Flow

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LAMINAR FLOW

Laminar flow: moving in a smooth, non-turbulent way

within the pipe

Characterized by smooth streamlines and highly-ordered

motion.

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TURBULENT FLOWTurbulent flow: more chaotic, and “violent” movement

within the pipe..

Turbulent flow: characterized by velocity fluctuations

and highly disordered motion

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TRANSITION FLOW

Transition flow: back-and-forth change between Laminar

and Turbulent flows

Transition flow is characterized by rapid, surging pressure

changes within the system, and generally chaotic,

unpredictable flow patterns

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FLUID FLOW

It is important to understand if a system is

experiencing Laminar, Turbulent or Transition

flow…

Because pumps and fluid transport systems and

control valves must be designed to work properly

under the real-world conditions that exist.

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FLUID FLOW

The transition from Laminar to Turbulent flow in pipes

depends on myriad physical parameters within the

fluid-flow system including:‒ Geometry or the system

‒ Roughness of the pipes

‒ Flow velocity

‒ Fluid density

‒ Fluid viscosity

‒ Fluid temperature (affects density & viscosity)

HOW DO WE PREDICT or QUANTIFY THESE

PARAMETERS?

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FLUID FLOW

Reynolds Number

Relationship to express this ratio for

particular physical situations using a single,

dimensionless number.

HOW DO WE PREDICT OF QUANTIFY THESE PARAMETERS?

Reynolds Number

Range

Observed Flow

Type

<2000 Laminar

2000-2300 Transition

>2300 Turbulent

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PIPING

Moving fluid through a piping SYSTEM = HEAD LOSS:1. Moving parallel to ground: against FRICTION of pipe material

2. Moving up/against GRAVITY.

Tank #1 Tank #2

1.

2.

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PIPINGMoving fluid through a piping SYSTEM:

1. Moving parallel to ground: against FRICTION of pipe material

The amount of friction and viscosity-induced resistance to flow within a

pipe is dependent upon many variables including:

• Velocity of fluid in the pipe

• Viscosity of the fluid

• Density of the fluid

• Geometry of the pipe (length & diameter)

• Relative smoothness of the pipe– piping material

• etc….

Fortunately, dedicated engineers and scientists have done the work to

develop equations and correlations that allow us to account for the

many factors that contribute to head loss due to pipe friction:

So, this data is included on pump specifications(Moody Diagrams and Churchill Equations).

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PIPING Moving fluid through a piping SYSTEM: HEAD LOSS

• Moving fluid against gravity/”up hill”

• Moves against PRESSURE

Water

P1

P2

P3

The pressure that is exerted by a COLUMN OF WATER

increases with increasing column height

Expressed in units of

“feet of water” (ftH2O)

or “inches of water” (inH2O)

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PIPING

GRAVITY HEAD LOSS

Tank #1 Tank #2hLelev = 20 ft

Height = 20 ft

Elevation head loss, hLelev, is easily calculated by determining the total height

differential between the pump discharge and the liquid discharge point within the

system to which the liquid is to be pumped.

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PIPING

Moving fluid through a piping SYSTEM = HEAD LOSS:1. FRICTION of pipe material

2. Moving up/against GRAVITY = MAJOR CONTRIBUTOR*

Tank #1 Tank #2

1.

2.

* Fluid has low-VISCOSITY (BEER)

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PUMPS Moving fluid through a piping SYSTEM = PUMPS

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PUMPS Moving fluid through a piping SYSTEM:

Pump Sizing

• Pumps are characterized by the liquid flow rate that can

be achieved when pumping against a certain amount of

pressure

Ex- a specification by a pump manufacturer might

state that a pump is “capable of 3.5 gpm flow at 14 feet

of head”

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PUMPS

• Pump requires energy.

• The rate at which work is done (work per

unit time) is the definition of power.

• Need More Power:

• Moving more liquid per unit time

• Moving liquid faster requires

• Moving liquid against a greater

resistance (pressure)

POWER UNIT = HORSE POWER (h.p.)

PUMP SIZING

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PUMPS PUMP EFFICIENCY

• Overall pump efficiency, h, is expressed as

the decimal form of a % (e.g. 85% = 0.85)

• Pump drive motor efficiencies vary

depending upon the size of the motor.

• Larger drive motors usually have

higher efficiency ratings

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PUMPS PUMP SIZING

Let’s look at our piping system example that we have been

using and try to estimate the size of the pump that we will

need to obtain our desired flow within the system.

Tank #1 Tank #2Pump

Valve

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PUMPS PUMP SIZINGHere’s a reminder of what we have, and what we

know so far that is relevant to sizing the pump:

• Liquid flow rate is 30 gpm

• hLtot = 31 ft

• Power requirements are given by:

• Efficiency can be estimated using vendor data:

𝑃𝑜𝑤𝑒𝑟 =𝑄 ∆𝑃𝑡𝑜𝑡𝑎𝑙1714 𝜂

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PUMPS PUMP SIZING

• There are two things we need to do:– Assume a value for pump drive efficiency

– Convert the value for total system head loss, hLtot, into units of psi

• Use vendor data, if available, to help you make assumptions about

a reasonable value for pump efficiency. Based on the data we

have, and my “engineering judgment” I will assume a value of h =

65% for pump drive efficiency (based on experience, I think it will

be a relatively small drive and therefore relatively inefficient….).

• Next, convert the units of hLtot = 31 ft into units of psi using the

conversion factor: 1 ftH2O = 0.4335 psi

31 𝑓𝑡𝐻2𝑂

1𝑥0.4335 𝑝𝑠𝑖

1 𝑓𝑡𝐻2𝑂= 13.4 𝑝𝑠𝑖 hLtot = 13.4 psi

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PUMPS PUMP SIZING

• We now have everything that we need in the

correct units:• Liquid flowrate = Q = 30 gpm

• DPtotal = hLtot = 13.4 psi

• Efficiency = 65% = 0.65

• Plugging these values into the equation:

• Gives:

𝑃𝑜𝑤𝑒𝑟 =𝑄 ∆𝑃𝑡𝑜𝑡𝑎𝑙1714 𝜂

𝑃𝑜𝑤𝑒𝑟 =(30 𝑔𝑝𝑚) (13.4 𝑝𝑠𝑖)

1714 (0.65)= 𝟎. 𝟑𝟔 𝒉. 𝒑.

To pump 30 gpm, we need at least a 0.36 h.p. pump.

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PUMPS PUMP SIZING

You are the head brewer at a large, regional brewery. The

brewery is expanding and installing 4 new lauter tuns. A piping

system with a single pump provides sparge water to the spray

nozzle headers in all 4 lauter tuns. The overall head loss

associated with the system, including all 4 lauter tuns, is 95 psi .

You need a pump that can provide at least 30 gpm to the spray

nozzle header in each lauter tun. It is possible that all four lauter

tuns might need to be sparging at the same time. What size pump

is required?

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PUMPS PUMP SIZING

𝑃𝑜𝑤𝑒𝑟 =𝑄 ∆𝑃𝑡𝑜𝑡𝑎𝑙1714 𝜂

𝑃𝑜𝑤𝑒𝑟 =(120𝑔𝑝𝑚) (95𝑝𝑠𝑖)

1714 (0.80)= 8.3 ℎ. 𝑝.

• Here’s what we know from the problem statement, and can assume:– We need to be able to deliver 4 x 30 gpm = 120 gpm sparge water

– Total system pressure is 95 psi

– This is likely a bigger system than in our previous example, so assume

efficiency of 80% (0.80)

• Use:

• Plug in the values:

To pump 120 gpm in this system, we need at least an 8.3 h.p. pump