Transcript PE Exam Review

Environmental Systems
and Facilities Planning
Doug Overhults
University of Kentucky
Biosystems & Agricultural Engineering
University of Kentucky
College of Agriculture
Topic Outline
Psychrometrics Review
Energy Balances/Loads
Latent heat
Sensible heat
Solar loads
Insulation Requirements
Topic Outline
Ventilation Systems
Rate requirements
System requirements
Moisture Control Standards
Air Quality Standards
Humans
Animals
Plants and Produce
Psychrometrics
Variables
Using the Psychrometric Chart
Psychrometric Processes
Psychrometric Chart
“Humidity”
Scale
or axis
State Point
Dry Bulb Temperature Scale (axis)
Psychrometric Chart
(temperatures + relative humidity)
Example:
relative
humidity
70 oF dry bulb
55 oF dew-point
61 oF wet-bulb
dew-point
60 % rh
wet bulb
dry bulb
Dry Bulb Temperature Scale
“Humidity”
Scale
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)
Evaporative cooling (constant wet-bulb
line)
Heating: dry bulb increase
Horizontal line means no
change in dew-point or
humidity ratio
starting state point
Dry Bulb Temperature Scale
“Humidity”
Scale
ending state
point
Humidification: dew-point increase
Vertical line means no
change in dry bulb
temperature
end state
RH goes up!
start state
Dry Bulb Temperature Scale
“Humidity”
Scale
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)
Air Density
“Humidity”
Scale
Wet bulb line
Humid Volume, 1/
ft3/lb da
Dry Bulb Temperature Scale
Review
Name three temperature variables
Name three measures of humidity
Name the two main axes of the
psychrometric chart
Name the line between fog and moist air
Heating or Cooling follow constant line of ?
Humidify/Dehumidify follow constant line
of ?
ENERGY AND MASS
BALANCES
Energy and Mass Balances
Heat Gain and Loss
Latent and Sensible Heat Production
Mechanical Energy Loads
Solar Load
Moisture Balance
Heat Gain and Loss
Occupants
Lighting
Equipment
Ventilation
Building Envelope
Roof, walls, floor, windows
Infiltration (consider under ventilation)
Heat Loads
Occupant (animals, people)
Sensible load (e.g. Btuh/person)
Latent load (“)
Lighting, W/m2
Appliance W/m2
Ventilation air (cfm/person or animal)
Equipment (e.g. Btuh for given items)
Ventilation
Temperature control
Moisture control
Contaminants (CO2, dust, NH3) control
Energy use
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 gH2O/kg-h
SHL
THL
1.1 W/kg 2.0 W/kg
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
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)
Mass Balance
Moisture, CO2, and other materials use balance equations.
mp
mvi
Material
produced
Material
input rate
+
mvo
=
material output rate
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
Wr – lbm / hr
W – lbm / lbda
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
SHL
THL
2.2 W/kg 3.3 W/kg
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
Plug into equation & solve
Q = (14.1/60) x [(.017 x 800) / (.0154 - .0005)]
Q = 214 cfm
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.
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 }
Get quantities in consistent units
• 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
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.
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
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
Fan Operating Cost
Electrical Power Cost
W
V
Power input,
Watts
Ventilation
volumetric
flow rate
=
÷
cfm / Watt
Fan Test Efficiency
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
Calculate Operating Costs
8 fans required for brand A or B
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 = $
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.
Reference
MWPS - 32
Contains ASABE heat & moisture
production data & example problems
Midwest Plan Service
Iowa State University
Ames, IA
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
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
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
FACILITIES
Manure Management Example
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
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
Net annual rainfall = 14 inches
25 yr. – 24 hr storm = 5.8 inches
Size a Manure Storage
Use EP 393, sections 5.1 & 5.3
Total volume has 5 components
Manure, Net rainfall, 25 yr-24 hr storm
Incomplete removal, Freeboard for
agitation
ManureVol 20* 2500* 2.7  135,000 ft
3
Size a Manure Storage
Manure Depth = 21.22 ft.
Net rain = 1.17 ft
25 yr-24 hr storm = 0.48 ft
Incomplete removal = 0.67 ft
Freeboard = 1 ft
Total Tank Depth = 24.54 ft.
References - Facilties
 Agricultural Wiring Handbook, 15th edition, Rural
Electricity Resource Council
 Farm Buildings Wiring Handbook, MWPS-28 (now
updated to 2005 code)
 Equipotential Plane in Livestock Containment Areas
ASAE, EP473.2
 Designing Facilities for Pesticide and Fertilizer
Containment, MWPS-37
 On-Farm Agrichemical Handling Facilities, NRAES78
 Farm and Home Concrete Handbook, MWPS-35
 Farmstead Planning Handbook, MWPS-2
(download only)
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
Thank You
and
Best Wishes for Success
on Your PE Exam ! !
University of Kentucky
College of Agriculture
Biosystems & Agricultural Engineering