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 Dry Bulb Temperature Scale (axis) “Humidity” Scale or axis State Point

Psychrometric Chart (temperatures + relative humidity) Dry Bulb Temperature Scale “Humidity” Scale dew-point wet bulb dry bulb Example: 70 o F dry bulb 55 o F dew-point 61 o F wet-bulb 60 % rh relative humidity

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 Dry Bulb Temperature Scale “Humidity” Scale ending state point starting state point Horizontal line means no change in dew-point or humidity ratio

Humidification: dew-point increase Dry Bulb Temperature Scale “Humidity” Scale start state end stateVertical line means no change in dry bulb temperature RH goes up!

Evaporation: wet bulb increase Dry Bulb Temperature Scale “Humidity” Scale start state end state Increase in vertical scale: humidified Decrease in horizontal scale: cooled Constant wet bulb line Adiabatic process – no heat gained or lost (evaporative cooling)

Air Density Dry Bulb Temperature Scale “Humidity” Scale Wet bulb line Humid Volume, 1/  ft 3 /lb da

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)

Building Ventilation Rate  Temperature control  Moisture control  Contaminants (CO 2, dust, NH 3 ) control  Need data for heat, moisture, or contaminant production in building  Energy use – VR is a major variable

Latent and Sensible Heat Production  Example from ASAE Standard EP270.5: Table 1. Moisture Production, Sensible Heat Loss, and Total Heat Loss Cattle Bldg. T MPSHL THL 500 kg 21C 1.3 gH2O/kg-h 1.1 W/kg 2.0 W/kg

Sensible Energy Balance  Leads to Ventilation for Temperature Control: q s + q so + q m + q h = Σ UA(t i -t o ) + FP(t i -t o ) + c p ρ V (t i -t o ) Heat inputs = envelope + floor + ventilation q s – sensible heat q so – solar heat gain q m – mechanical heat sources q h – supplemental heat U – building heat transfer coeff. P – floor perimeter F – perimeter heat loss factor c p – specific heat of air V – ventilation rate ρ – density of air

Sensible Energy Balance  Leads to Ventilation for Temperature Control. Rearranging: V = [ q s - ( Σ UA+ FP)(t i -t o )] / 0.24 ρ (t i -t o )60 V – cfm (equation for English units)

Mass Balance =+ m p Material produced m vi Material input rate m vo material output rate Moisture, CO2, and other materials use balance equations.

Moisture Balance = m air Ventilation rate M water Moisture to be removed Example balance for moisture control removal rate. (W i -W o ) Humidity ratio difference / Q = (V / 60) x [ W r / (W i -W o ) ] Q - cfm V – ft 3 /lb da W r – lb m / hr W – lb m / lb da

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. Moisture Balance ASABE D270.5 Nursery Pigs Bldg. T MPSHL THL kg 29C 1.7 gH2O/kg-h 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) W r = lb/hr/pig Get psychrometric data from chart W 0 = Wi = V = 14.1

Moisture Balance = m air Ventilation rate M water Moisture to be removed (W i -W o ) Humidity ratio difference / Q = (V / 60) x [ W r / (W i -W o ) ] Put data into equation & solve Q = (14.1/60) x [(.017 x 800) / ( )] Q = 214 cfm

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. NH 3 Balance

NH 3 Solution Use volumetric form of mass balance equation V p + V i = V o V p + Q v [NH 3 ] i = Q v [NH 3 ] o Solve for Q v Q v = V p / { [NH 3 ] o - [NH 3 ] i } Volumetric NH 3 production rate per minute V p = (21.6 ft 3 /hr / 60 min/hr) = 0.36 ft 3 /min Plug into equation & solve Q = 0.36 / ( )] Q = 0.36 / Q = 20,000 cfm

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. 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 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 Btu/hr W = 167,188 Btu/hr Density of Air = lb/ft 3 Specific heat of air = 0.24 Btu/lb F t i – t o = 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 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 V = [ q s - ( Σ UA+ FP)(t i -t o )] / 0.24 ρ (t i -t o )60

 Building Heat Loss  Q b = (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. Insulation

Wall Section - Resitances in Series

Insulation & Heat Loss Need R-value for each component

 Q b = (A/R) T x ∆t (Btu/hr) Walls - Q w = (A w /R w ) x ∆t Doors - Q d = (A d /R d ) x ∆t Ceiling - Q c = (A c /R c ) 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  Q p = (L p /R p ) x ∆t Insulation & Heat Loss

 Q bldg = (A/R) w x ∆t + (A/R) d x ∆t + (A/R) c x ∆t  ∆t is the same for all components Q bldg =  (A i /R i ) x ∆t (A/R) Total =  (A i /R i ) sum of all (area/resistance) ratios for all components of the building i.e. walls, ceiling, doors, windows, etc.  Q bldg = (A/R) Total x ∆t Building Heat Loss

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 ft 2 F/Btu in). R-values for the top 1/3 and bottom 2/3 of the existing wall are 12 and 6 (hr ft 2 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? Insulated Wall Problem

R-value of added insulation (2 inches) R foam = 2 x 6 = 12 New R-values R upper = = 24 R lower = = 18 No area given – solve for a unit area (1/3 upper & 2/3 lower) Insulated Wall Solution

What is Q after /Q before 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= 0.33/ /6 = New – Wall A/R= 0.33/ /18 = Ratio New/Old= 0.051/0.139 = Insulated Wall Solution

Fan Operating Cost =÷ W Power input, Watts V Ventilation volumetric flow rate cfm / Watt Fan Test Efficiency Electrical Power Cost

Calculate Operating Costs  Design Ventilation Rate – 169,700 cfm  Fan Choices Brand A – 21, cfm/watt Brand B – 22, cfm/watt  Fans operate 4000 hours per year  Electricity cost - $0.10 per kWh  Calculate annual operating cost difference

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

Calculate Operating Costs  Use EP 566, Section 6.2  Annual cost is for all 8 fans Watts * hrs * $/kWh * kWh/Wh = $

References – Env. Systems  Albright, L.D Environment Control for Animals and Plants. ASAE  Hellickson, M.A. and J.N. Walker Ventilation of Agricultural Structures. ASAE  ASHRAE Handbook of Fundamentals

Reference MWPS - 32 Contains ASABE heat & moisture production data & example problems Midwest Plan Service Iowa State University Ames, IA

Reference MWPS - 1 Broad reference to cover agricultural facilities, structures, & environmental control Midwest Plan Service Iowa State University Ames, IA STRUCTURES and ENVIRONMENT HANDBOOK

Useful References – Env Sys  MidWest Plan Service MWPS-32, Mechanical Ventilation Systems for Livestock Housing.  Greenhouse Engineering (NRAES – 33) ISBN http://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 ft 3 /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

Size a Manure Storage  Manure Depth = 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 = 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, NRAES- 78  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