brewing engineering part 1 - beer brewing school ......density defined: the mass of a material that...
TRANSCRIPT
BREWING ENGINEERING part 1
BREWING ENGINEERING
OBJECTIVES FOR PART 1:
• FLUIDS• FLUID PHYSICAL PROPERTIES• FLUID FLOW• PIPING• PUMPS- 1
BREWING ENGINEERING
OBJECTIVES:
BREWING ENGINEERING
FLUID
BREWING ENGINEERING
Types of substances that can be
classified as fluids include• Liquids
• Gases
• Plasmas
FLUID
BREWING ENGINEERING
LIQUID
BREWING ENGINEERING
LIQUID
BREWING ENGINEERING
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
BREWING ENGINEERING
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.)
BREWING ENGINEERING
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
BREWING ENGINEERING
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.
BREWING ENGINEERING
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:
BREWING ENGINEERING
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
BREWING ENGINEERING
SPECIFIC GRAVITY
Hydrometers are tools used to measure the specific gravity of a
liquid
BREWING ENGINEERING
SPECIFIC GRAVITY
Hydrometers
BREWING ENGINEERING
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:
BREWING ENGINEERING
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
BREWING ENGINEERING
VISCOSITY
Viscosity is a strong function of temperature, so viscosity data
always includes some reference to the temperature.
BREWING ENGINEERING
VISCOSITY
Viscosity is a strong function of temperature.
Water
T = cooler
Molecules closer together
Water
T = warmer
Molecules farther apart
BREWING ENGINEERING
VISCOSITY
Viscosity is also a function of pressure.
Water
P = higher
Molecules (slightly) closer together
Water
P = Lower
Molecules (slightly) farther apart
Pressure Pressure
BREWING ENGINEERING
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)
BREWING ENGINEERING
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
BREWING ENGINEERING
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
BREWING ENGINEERING
FLUID FLOW
In the brewery we are primarily concerned with “water-like”
fluids flowing through systems of pumps, pipes, hoses,
valves, and nozzles.
BREWING ENGINEERING
FLUID FLOW
3 TYPES OF FLOW:
1. Laminar Flow
2. Turbulent Flow
3. Transition Flow
BREWING ENGINEERING
LAMINAR FLOW
Laminar flow: moving in a smooth, non-turbulent way
within the pipe
Characterized by smooth streamlines and highly-ordered
motion.
BREWING ENGINEERING
TURBULENT FLOWTurbulent flow: more chaotic, and “violent” movement
within the pipe..
Turbulent flow: characterized by velocity fluctuations
and highly disordered motion
BREWING ENGINEERING
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
BREWING ENGINEERING
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.
BREWING ENGINEERING
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?
BREWING ENGINEERING
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
BREWING ENGINEERING
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.
BREWING ENGINEERING
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).
BREWING ENGINEERING
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)
BREWING ENGINEERING
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.
BREWING ENGINEERING
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)
BREWING ENGINEERING
PUMPS Moving fluid through a piping SYSTEM = PUMPS
BREWING ENGINEERING
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”
BREWING ENGINEERING
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
BREWING ENGINEERING
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
BREWING ENGINEERING
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
BREWING ENGINEERING
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
BREWING ENGINEERING
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
BREWING ENGINEERING
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.
BREWING ENGINEERING
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?
BREWING ENGINEERING
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