Transcript PE Exam Review

Environmental Systems
and Facilities Planning
Dr. Doug Overhults, PE
University of Kentucky
Biosystems & Agricultural Engineering
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Topic Outline
Psychrometrics Review
Energy Balances/Loads
Latent heat
Sensible heat
Insulation Requirements
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Topic Outline
Ventilation Systems
Rate requirements
System requirements
Moisture Control Standards
Air Quality Standards
Humans
Animals
Plants and Produce
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Psychrometrics
Variables
Using the Psychrometric Chart
Psychrometric Processes
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Psychrometric Chart
“Humidity”
Scale
or axis
State Point
Dry Bulb Temperature Scale (axis)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Psychrometric Chart
(temperatures + relative humidity)
Example:
relative
humidity
70 oF dry bulb
55 oF dew-point
61 oF wet-bulb
“Humidity”
Scale
dew-point
60 % rh
wet bulb
dry bulb
Dry Bulb Temperature Scale
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Psychrometric Processes
Heating, cooling, humidifying,
dehumidifying air-water vapor
mixtures
Five basic processes to know
Heat or Cool (horizontal line)
Humidify or De-humidify (vertical line)
Evaporation (constant wet-bulb line)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Heating: dry bulb increase
“Humidity”
Scale
Horizontal line means no
change in dew-point or
humidity ratio
ending state
point
starting state point
Dry Bulb Temperature Scale
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Humidification: dew-point increase
Vertical line means no
change in dry bulb
temperature
end state
“Humidity”
Scale
RH goes up!
start state
Dry Bulb Temperature Scale
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Evaporation: wet bulb increase
Increase in vertical
scale: humidified
end state
“Humidity”
Scale
Decrease in horizontal
scale: cooled
Constant wet bulb line
start state
Dry Bulb Temperature Scale
Adiabatic process – no heat gained or lost (evaporative cooling)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Air Density
“Humidity”
Scale
Wet bulb line
Humid Volume, 1/
ft3/lb da
Dry Bulb Temperature Scale
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Review
Name three temperature variables
Name three measures of humidity
Name the two main axes of the
psychrometric chart
What is the line between fog and moist air?
Heating/Cooling follows line of constant _?
Humidify/Dehumidify follows line of
constant _____?
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
ENERGY AND MASS
BALANCES
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Energy and Mass Balances
Heat Gain and Loss
Latent and Sensible Heat Production
Mechanical Energy Loads
Solar Load
Moisture Balance
Contaminants (gas/dust) Balance
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Heat Gain and Loss
Occupants
Lighting
Equipment
Ventilation
Building Envelope
Roof, walls, floor, windows
Infiltration (consider under ventilation)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Heat Loads
Occupant (animals, people)
Sensible load (e.g. Btuh/person)
Latent load (lb moisture/occupant)
Lighting, W/m2
Appliance W/m2
Ventilation air (cfm/person or animal)
Equipment (e.g. Btuh for given items)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Building Ventilation Rate
Temperature control
Moisture control
Contaminants (CO2, dust, NH3) control
Need data for heat, moisture, or
contaminant production in building
Energy use – VR is a major variable
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Latent and Sensible Heat
Production
Example from ASAE Standard
EP270.5:
Table 1. Moisture Production, Sensible Heat Loss,
and Total Heat Loss
Cattle
500 kg
Bldg. T
21C
MP
1.3 g(H2O)/kg-h
University of Kentucky
College of Agriculture, Food, & Environment
SHL
THL
1.1 W/kg 2.0 W/kg
Biosystems & Agricultural Engineering
Sensible Energy Balance
Leads to Ventilation for Temperature
Control:
qs + qso + qm + qh = ΣUA(ti-to) + FP(ti-to) + cpρV (ti-to)
Heat inputs
=
envelope + floor + ventilation
qs – sensible heat
qso – solar heat gain
qm – mechanical heat sources
qh – supplemental heat
U – building heat transfer coeff.
P – floor perimeter
F – perimeter heat loss factor
cp – specific heat of air
V – ventilation rate
ρ – density of air
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Sensible Energy Balance
Leads to Ventilation for Temperature
Control. Rearranging:
V = [ qs - ( Σ UA+ FP)(ti-to)] / 0.24 ρ (ti-to)60
V – cfm
(equation for English units)
University of Kentucky
College of Agriculture, Food, & Environment
Assumed zero
qso – solar heat gain
qm – mechanical heat sources
qh – supplemental heat
Biosystems & Agricultural Engineering
Energy Balance
What is the ventilation rate for a swine finishing
barn that will limit the design temperature rise
inside the house to 4 degrees (F) above the
ambient temperature? The barn capacity is 1000
pigs at 220 pounds and the inside temperature is
approximately 85 F. The overall heat transfer
coefficient for the barn is 1200 Btu/hr F.
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
What is the ventilation rate for a swine finishing barn that will
limit the design temperature rise inside the house to 4 degrees (F)
above the ambient temperature? The barn capacity is 1000 pigs at
220 pounds and the inside temperature is approximately 85 F. The
overall heat transfer coefficient is 1200 Btu/hr F.
•
Find heat production data
• ASABE Standards (EP270.5)
• q = 0.49 W/kg (sensible heat)
•
Convert units & calculate total heat load
• q = 0.49 W/kg x 100 kg/pig x 1000 pigs
•
= 49,000 W x 3.412 Btu/hr W
•
= 167,188 Btu/hr
•
•
•
Density of Air = 0.075 lb/ft3
Specific heat of air = 0.24 Btu/lb F
ti – to = 4 F
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Continuation . . . ventilation rate for a swine finishing barn that
will limit the design temperature rise inside the house to 4 degrees
(F) above the ambient temperature
•
Basic equation
V = [ qs - ( Σ UA+ FP)(ti-to)] / 0.24 ρ (ti-to)60
•
Neglect floor heat loss or gain
•
•
•
Plug into equation & solve
V = [167,188 - (1200 x 4)] / [(0.24 x 0.075) x 4 x 60]
V = 37,590 cfm
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Mass Balance
Moisture, CO2, and other materials use balance equations.
mp
mvi
Material
produced
Material
input rate
generation rate
+
incoming rate
University of Kentucky
College of Agriculture, Food, & Environment
mvo
=
material output rate
removal or emission rate
Biosystems & Agricultural Engineering
Moisture Balance
Example mass balance for moisture control removal rate.
/
Mair
Mwater
Ventilation
rate
Moisture to
be removed
Humidity ratio
difference
(lb h2o/hr)
(lb h2o / lb da)
=
(lb da/hr)
Mair = Q*60/V
(Wi-Wo)
Q – ventilation rate, cfm
V – specific volume of air, ft3/lb da
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Moisture Balance
Example balance for moisture control removal rate.
/
mair
Mwater
Ventilation
rate
Moisture to
be removed
=
(Wi-Wo)
Humidity
ratio
difference
Q = (V / 60) x [ Wr / (Wi-Wo) ]
Q - cfm
V – ft3/lbda
University of Kentucky
College of Agriculture, Food, & Environment
Wr – lbm / hr
W – lbm / lbda
Biosystems & Agricultural Engineering
Moisture Balance
Find the minimum winter ventilation rate to maintain
60% relative humidity inside a swine nursery that has
a capacity of 800 pigs weighing 10 pounds. Inside
temperature is 85 degrees.
ASABE D270.5
Nursery
Pigs
4 - 6 kg
Bldg. T
MP
29C
1.7 gH2O/kg-h
University of Kentucky
College of Agriculture, Food, & Environment
SHL
THL
2.2 W/kg 3.3 W/kg
Biosystems & Agricultural Engineering
Find the minimum winter ventilation rate to maintain
60% relative humidity inside a swine nursery that has
a capacity of 800 pigs weighing 10 pounds. Inside
temperature is 85 degrees.
•
•
Find moisture production data
• ASABE Standards (EP270.5)
• Wr = 0.017 lb/hr/pig
Get psychrometric data from chart
• W0 = 0.0005
• Wi = 0.0154
• V = 14.1
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Moisture Balance
mair
Mwater
Ventilation
rate
Moisture to
be removed
=
/
(Wi-Wo)
Humidity
ratio
difference
Q = (V / 60) x [ Wr / (Wi-Wo) ]
•
•
•
Put data into equation & solve
Q = (14.1/60) x [(.017 x 800) / (.0154 - .0005)]
Q = 214 cfm
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
NH3 Balance
Find the ventilation rate required to prevent the
ammonia concentration inside a poultry layer barn
from rising above 20 ppm. Ammonia production
in the barn is estimated to be 21.6 cubic feet
per hour. Ammonia concentration in the
ambient air is 2 ppm.
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
NH3 Solution
•
•
•
•
•
•
Use volumetric form of mass balance equation
• Vp + Vi = Vo
• Vp + Qv[NH3]i = Qv[NH3]o
• Solve for Qv
• Qv = Vp / { [NH3]o - [NH3]i }
Volumetric NH3 production rate per minute
• Vp = (21.6 ft3/hr / 60 min/hr) = 0.36 ft3/min
Plug into equation & solve
Q = 0.36 / (.000020 - .000002)]
Q = 0.36 / .000018
Q = 20,000 cfm
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulation
Building Heat Loss
Qb = (A/R)T x ∆t
(A/R)T = sum of all (area/resistance)
ratios for all components of the building
i.e. walls, ceiling, doors, windows, etc.
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulation
Wall Section Resitances in Series
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulation & Heat Loss
Need R-value for each component
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulation & Heat Loss
Qb = (A/R)T x ∆t
(Btu/hr)
Walls - Qw = (Aw/Rw) x ∆t
Doors - Qd = (Ad/Rd) x ∆t
Ceiling - Qc = (Ac/Rc) x ∆t
Proceed through all components
Perimeter is special case
 R-value is per unit of length - essentially
assumes a 1 ft width along perimeter
 Qp = (Lp/Rp) x ∆t
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Building Heat Loss
Qbldg = (A/R)w x ∆t + (A/R)d x ∆t
+ (A/R)c x ∆t + . . . . .
∆t is the same for all components
 Qbldg = (Ai/Ri) x ∆t
 (A/R)Total = (Ai/Ri) sum of all (area/resistance)
ratios for all components of the building i.e.
walls, ceiling, doors, windows, etc.
Qbldg = (A/R) Total x ∆t
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulated Wall Problem
The wall of a poultry house will be insulated on the inside by adding
2 inches of spray foam insulation. The R-value of the spray foam
insulation is 6 per inch of thickness (hr ft2 F/Btu in). R-values for
the top 1/3 and bottom 2/3 of the existing wall are 12 and 6 (hr ft2
F/Btu), respectively. No other changes are made. What is the heat
loss through the wall after the foam insulation is added as a fraction
of the heat loss through the existing wall?
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulated Wall Solution
R-value of added insulation (2 inches)
Rfoam = 2 x 6 = 12
New R-values
Rupper = 12 + 12 = 24
Rlower = 12 + 6 = 18
No area given – solve for a unit area (1/3 upper & 2/3 lower)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Insulated Wall Solution
What is Qafter/Qbefore
No ∆t given but no change between before & after
The end result is a ratio of heat losses, so ∆t will be
the same in numerator & denominator. All that remains
is a ratio of the new & old A/R values.
Existing –
Wall A/R
New –
Wall A/R
Ratio New/Old
= 0.33/12 + 0.67/6
= 0.139
= 0.33/24 + 0.67/18
= 0.051
= 0.051/0.139 = 0.367
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Fan Operating Cost
Electrical Power Cost
W
V
Power input,
Watts
Ventilation
volumetric
flow rate
=
University of Kentucky
College of Agriculture, Food, & Environment
÷
cfm / Watt
Fan Test Efficiency
Biosystems & Agricultural Engineering
Calculate Operating Costs
Design Ventilation Rate – 169,700 cfm
Fan Choices
Brand A – 21,300 cfm @ 19.8 cfm/watt
Brand B – 22, 100 cfm @ 16.2 cfm/watt
Fans operate 4000 hours per year
Electricity cost - $0.10 per kWh
Calculate annual operating cost
difference
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Calculate Operating Costs
Determine number of fans required
Brand A - 169,700/21,300 = 7.97
Brand B - 169,700/22,100 = 7.68
8 fans required for brand A or B
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Calculate Operating Costs
Use EP 566, Section 6.2
Annual cost is for all 8 fans
 176,800 170,400


 * 4,000* $0.10* 0.001 $923.01
19.8 
 16.2
Watts
* hrs
* $/kWh * kWh/Wh = $
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
References – Env. Systems
 Albright, L.D. 1990. Environment Control
for Animals and Plants. ASAE
 Hellickson, M.A. and J.N. Walker. 1983.
Ventilation of Agricultural Structures.
ASAE
ASHRAE Handbook of Fundamentals. 2009.
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Reference
MWPS - 32
Contains ASABE heat & moisture
production data & example problems
Midwest Plan Service
Iowa State University
Ames, IA
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Reference
MWPS - 1
STRUCTURES and
ENVIRONMENT
HANDBOOK
Broad reference to cover agricultural
facilities, structures, & environmental control
Midwest Plan Service
Iowa State University
Ames, IA
www.mwps.org
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Useful References – Env Sys
MidWest Plan Service. 1990. MWPS-32,
Mechanical Ventilation Systems for
Livestock Housing.
Greenhouse Engineering (NRAES – 33)
ISBN 0-935817-573http://palspublishing.cals.cornell.edu/nra
_order.taf
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
References – ASAE Standards
 EP270.5 – Ventilation systems for poultry and
livestock
 EP282.2 – Emergency ventilation and care of animals
 EP406.4 – Heating, ventilating cooling greenhouses
 EP460 – Commercial Greenhouse Design and Layout
 EP475.1 – Storages for bulk, fall-crop, irish potatoes
 EP566 – Selection of energy efficient ventilation fans
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
FACILITIES
Manure Management Example
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Manure Management Facilities
Animal Manure Production
Nutrient Production
Design Storage Volumes
Lagoon – Minimum Design Volume
References
ASAE – EP 384.2, 393.3, 403.3, 470
NRCS – Ag. Waste Field Handbook
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Size a Manure Storage
1 year storage
Above ground 90’ dia. tank – uncovered
2500 hd capacity – grow/finish pigs
Building turns over 2.7 times/yr
Manure production 20 ft3/finished animal
(ASABE D384.2)
Wastewater – 50 gal/yr/pig space
Net annual rainfall = 14 inches
25 yr. – 24 hr storm = 5.8 inches
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Size a Manure Storage
Use EP 393, sections 5.1 & 5.3
Total volume has 6 components
Manure, Wastewater, Net rainfall,
25 yr-24 hr storm, Incomplete removal,
Freeboard for agitation
ManureVol  20 * 2500 * 2.7  135,000 ft 3
WastewaterVol  50 * 2500 / 7.5  16,667 ft 3
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Size a Manure Storage
Manure Depth = 23.84 ft.
Net rain = 1.17 ft
25 yr-24 hr storm = 0.48 ft
Incomplete removal = 0.67 ft
Freeboard/agitation = 1 ft
Total Tank Depth = 27.16 ft.
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
References - Facilties
 Agricultural Wiring Handbook, 16th edition (2011
Code) Rural Electricity Resource Council
 Farm Buildings Wiring Handbook, MWPS-28 (2013 ed.)
 Equipotential Plane in Livestock Containment Areas
ASAE, EP473.2
 Designing Facilities for Pesticide and Fertilizer
Containment, MWPS-37
 On-Farm Agrichemical Handling Facilities, NRAES-78
 Farm and Home Concrete Handbook, MWPS-35
 Farmstead Planning Handbook, MWPS-2 (download)
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
References – ASAE Standards
 D384.2 – Manure Production and Characteristics
 EP393.3 – Manure Storages
 EP403.4 – Design of Anaerobic Lagoons for Animal
Waste Management
 EP470.1 – Manure Storage Safety
 S607 – Ventilating Manure Storages to Reduce
Entry Risks
University of Kentucky
College of Agriculture, Food, & Environment
Biosystems & Agricultural Engineering
Thank You
and
Best Wishes for Success
on Your PE Exam ! !
University
UniversityofofKentucky
Kentucky
College
CollegeofofAgriculture,
AgricultureFood, & Environment
Biosystems
& Agricultural
Engineering
Biosystems
& Agricultural
Engineering