IDEC SYSTEMS SAVE ENERGY WHILE REDUCING DEMAND ON GRID
August 3, 2011 Tom Colvin, P.E., LEEDAP, DBIA Colvin Engineering Associates, Inc.
EVAPORATIVE COOLING BENEFITS
ENERGY CONSERVATION REDUCES DEMAND ON UTILITY PEAK DAYS HIGH INDOOR AIR QUALITY REDUCES BUILDING OPERATING COSTS
CONSIDER EVAPORATIVE COOLING FOR ALL PROJECTS LOCATED IN DRY CLIMATE
BETTER IAQ DURING COOLING HOURS REDUCED ENERGY COSTS SAME EQUIPMENT CAN BE USED FOR HUMIDIFICATION DURING WINTER WITH NO STEAM BOILER AND ASSOCIATED MAINTENANCE.
ECONOMIC COMPARISONS
PAYBACK PERIOD IN UTAH IS USUALLY 4 5 YEARS FOR BUILDINGS WITH TYPICAL OFFICE HOURS OPERATING SCHEDULE (55 hrs/wk) SAVES ABOUT 80% OF CHILLER TON-HOURS BASED ON $0.03/KWH + $12/KW DEMAND COST 12 MEDIA & 6R/10FPI COIL ADDS $0.55/CFM 30% LESS CHILLER SAVES $0.33/CFM NET FIRST COST PREMIUM = $0.22/CFM + PIPING BUILDINGS WITH LARGE OUTSIDE AIR REQUIREMENTS OR INCREASED HOURS OF OPERATION DECREASE PAYBACK PERIOD
DEMAND REDUCTION FOR UTILITY COMPANY
SINCE CHILLERS IN AN IDEC SYSTEM ARE TYPICALLY
SIZED AT 60-70% OF THE CALCULATED COOLING LOAD, THE MAXIMUM POWER DEMAND FOR THE BUILDING IS REDUCED; EVEN ON DAYS WITH CHILLERS AT FULL LOAD.
INDIRECT/DIRECT (IDEC) SYSTEMS PROVIDE MAXIMUM REDUCTION IN POWER DEMANDS WHEN OUTSIDE AIR TEMPERATURES ARE HOTTEST
CHILLERS IN SLC RARELY OPERATE WHEN OUTSIDE TEMPERATURE IS ABOVE 92F
CHILLERS NEVER OPERATE WHEN OUTSIDE TEMPERATURE IS ABOVE 95F (UTILITY PEAK DAYS)
THE EVAPORATIVE COOLING PROCESS
WHAT ARE THE STEPS?
WHAT IS WET-BULB DEPRESSION? WHY IS TWO-STAGE PROCESS BETTER THAN
TYPICAL SINGLE STAGE USED IN MOST RESIDENTIAL APPLICATIONS?
Process 1 Indirect Evaporative Cooling
Water in coil must be cooler
than entering air Air heat passes into water through a coil or other exchanger Enthalpy changes Wet-bulb temperature of airstream is depressed Humidity is constant Limited by both wet bulb temperature and heat exchanger 100% outside air is not required
Process 2: Direct Evaporation
Distribution Pipe Flow Meter Flow Balancing Valve Optional Filter Ball Valve Bleed Off Ball Valve
Ball Valve
Sump or trough Drain
Float valve
Process 2: Direct Evaporative Cooling
Rigid Media & sump systems
Water is absorbed by airstream
passing through media Air dry bulb temperature is lowered Enthalpy is unchanged Relative Humidity of airstream rises Leaving dry-bulb temperature is limited by the wet bulb temperature of the entering air
Typical IDEC Air Handler
Simple IDEC Piping System
IDEC AIR HANDLERS
3-stage cooling process.
Indirect cooling coil with low approach cooling tower. Provides wet-bulb depression of SA from 62F WB to 53F WB. Combination of 3F approach cooling tower selection and a 6 row pre-cooling coil provides a leaving DB air temperature of 6F above outdoor wet bulb. Chilled water coil (only used on high wet-bulb days) Evaporative media (12) - 90% saturation efficiency.
INDIRECT + DIRECT + REFRIGERATION
Health Issues for Evaporative Cooling
Legionella Pneumophila is unable to enter the airstream without aerosolizing the water Spray systems (NOT recommended) require high-efficiency mist
eliminators and sump water treatment to minimize Legionella risk. Rigid Media systems cannot aerosolize Legionella bacteria
The water is exposed to the air via the extended surface of the evaporative media. Only pure water is evaporated. Minerals and organisms remain in the re-circulating system and are removed by continuous bleed and draindown/flush cycle. Organisms can grow on the surface of the media and cause annoying odors if not properly flushed.
Controlling the potential growth of Legionella
Temperature affects the survival of Legionellae as follows:
70 to 80 C (158 to 176 F): Disinfection range
Above 50 C (122 F): Survive but do not multiply 35 to 46 C (95 to 115 F): Ideal growth range
20 to 50 C (68 to 122 F): Legionellae growth range
Below 20 C (68 F): Legionellae can survive but are dormant
(EVAPORATIVE COOLING RANGE)
LOWER CONNECTED LOAD
SINCE MOST CHILLERS ARE SIZED AT ONLY 60% - 70% OF THE CALCULATED COOLING LOAD; THE MAXIMUM BUILDING DEMAND IS REDUCED EVEN AT FULL CHILLER LOAD.
CHILLERS NEVER RUN EXCEPT DURING JUNE, JULY, AND AUGUST. CHILLERS ARE RARELY REQUIRED FOR 9MONTH SCHOOLS (SEPT-MAY)
DESIGN GUIDELINES
DISCHARGE AIR
TEMPERATURE MUST ALWAYS BE < 55F TO MAINTAIN SPACE HUMIDITY < 50% RH
REMEMBER THIS! THE AIR LEAVING A
12 DEEP RIGID MEDIA IS EXACTLY THE SAME HUMIDITY AS AIR LEAVING A WET CHILLED WATER COIL IF BOTH AIRSTREAMS ARE SAME TEMPERATURE!
MECHANICAL REFRIGERATION
ONLY A FEW CLIMATES HAVE WETBULB TEMPERATURES LOW
ENOUGH TO PROVIDE 55 F DISCHARGE AIR DURING ALL HOURS USING ONLY THE EVAPORATIVE PROCESS.
MECHANICAL REFRIGERATION IS NECESSARY TO SUPPLEMENT
THE EVAP PROCESS DURING HOURS WITH HIGHER WETBULB TEMPERATURES. OBSERVED CHILLER OPERATION IN VARIOUS YEARS RANGES FROM 200-400 HOURS/YEAR IN UTAH
TYPICAL JULY IN SLC (WORST MONTH) HAS ABOUT 60% HOURS
WHEN HUMIDITY RATIO EXCEEDS 50 GR/LB (REQUIRES REFRIGERATION). JULY 2011 HAD 85% OF THE HOURS WITH hr > 50 GR/LB.
CHILLER OPERATION
MOST COST EFFECTIVE LARGE SYSTEM PIPES CHILLER CONDENSER IN SERIES WITH INDIRECT COOLING COILS LOW TEMPERATURE CONDENSER WATER REQUIRES SPECIAL ATTENTION TO HEAD PRESSURE CONTROL ON CHILLER REMOVING CONDENSER FROM CIRCUIT WHEN CHILLERIS NOT REQUIRED REDUCES PUMP ENERGY
INDIRECT STAGE
FIRST STAGE SHOULD BE INDIRECT VS. DIRECT
(WET-BULB DEPRESSION)
EASIER TO CONTROL DISCHARGE AIR
TEMPERATURE REDUCES WET-DRY CYCLING OF DIRECT EVAP MEDIA
REDUCES ODORS COMMON DURING FIRST FEW MINUTES OF WETTING MEDIA INCREASES LIFE SPAN OF MEDIA
INDIRECT STAGE (contd)
COOLING TOWER SIZED FOR <4F APPROACH AND
15F - 18F RANGE
PIPING THE CONDENSER IN SERIES WITH THE
INDIRECT COILS CAN REDUCE COST AND INCREASE PERFORMANCE WHEN RANGE IS LOWER VFD CONTROL OF COOLING TOWER FANS TO CONTROL THE DAT IS DESIRABLE AND COST EFFECTIVE
INDIRECT STAGE (contd)
FLOW RATE FOR COOLING TOWER DETERMINED BY
REQUIRED FLOW FOR INDIRECT COILS HIGHER FLOW THAN CHILLER REQUIREMENTS
USUALLY AN 8F DELTA T ON COIL WORKS WELL WITH
6R/10FPI COIL WITH 2.5F - 3.0F APPROACH ADDING A 10F - 12F DELTA T FOR CONDENSER YIELDS THE RECOMMENDED 18F - 20F RANGE FOR COOLING TOWER
REALITY IN UTAH
Spaces always <50% RH at 72F if the
DAT is maintained at 55F or lower. Chillers are rarely needed when OSA temperature is above 92F resulting in lower power demand and 80% reduction in annual energy use for refrigeration. Chillers generally operate when OSA DB is 80F-85F
SOME EXAMPLES
SCOWCROFT IRS BUILDING - OGDEN
DISPLACEMENT VENTILATION UFAD
ONE UTAH CENTER SLC VAV OFFICES MERIT MEDICAL PRODUCTION BUILDING LOTS
OF EXHAUST AIR INJECTION MOLDING
SCOWCROFT EXTERIOR
SCOWCROFT BUILDING
RENOVATION OF A HISTORIC FOUR STORY BRICK AND WOOD WAREHOUSE BUILDING INTO OFFICES FOR THE IRS.
UNDERFLOOR AIR DISTRIBUTION SYSTEM ALLOWS EACH OCCUPANT TO ADJUST TEMPERATURE IN THEIR OWN CUBICLE. 100% OUTSIDE AIR DURING ALL HOURS ABOVE 55F AMBIENT, DISCHARGES INTO BREATHING ZONE.
SCOWCROFT ATRIUM
SCOWCROFT BUILDING
BUILDING OPERATING SINCE 2004 AND CHILLER
HAS RUN A TOTAL OF 4424 HOURS (632/yr) BUILDING ACHIEVED A LEED SILVER RATING FROM THE USGBC. BUILDING RECEIVED AN ENERGY STAR RATING IN 2008 WITH A SCORE OF 75. (88 BTU/SF-YR) UFAD SYSTEM ALLOWS THE BUILDING TO OPERATE WITH DISCHARGE AIR TEMPERATURES ABOVE 60 F WHEN OUTSIDE HUMIDITY IS LOW
SCOWCROFT BUILDING
DIRECT EVAPORATIVE MEDIA IS ARRANGED WITH ONE 4 DEEP PAD AND ONE 8 DEEP PAD TO ALLOW LOWER SATURATION EFFICIENCY DURING HOURS WHEN OUTSIDE WET-BULB IS LOW AND DAT TEMPERATURE IS ABOVE 55F WITHOUT RAISING INDOOR HUMIDITY TOO HIGH.
AIRHANDLERS HAVE REHEAT COILS AVAILABLE TO
CONTROL HUMIDITY ON HUMID DAYS.
SCOWCROFT BUILDING
PER BUILDING ENGINEER, SYSTEM WORKS VERY WELL. COMFORT COMPLAINTS ARE MINOR EVEN THOUGH 95% OF OCCUPANTS ARE FEMALE WORKING FOR THE IRS IN SMALL CUBICLES. EVEN THOUGH BUILDING SYSTEMS OPERATE 132 HRS/WEEK, ENERGY USE IS 25.4 KWH/SF-YR. ANNUAL ELECTRICAL COST IS $1.30/SF ANNUAL GAS HEATING COST IS $0.15/SF WORK HOURS ARE 125 HRS/WEEK, 22 HRS/DAY, 6 DAYS/WEEK
WHAT ABOUT SMALLER PACKAGED EQUIPMENT?
SOME IDEC PRODUCTS THAT ARE PREMANUFACTURED VS. FIELD BUILT
SPEAKMAN 5 TON MODULES 2. COOLERADO 3-10 TON MODULES 3. MUNTERS CUSTOM ANY SIZE UP TO 75,000 CFM IN A SINGLE UNIT
1.
How it Works
FEATURES & BENEFITS
Nominal 5 tons of cooling with 1750 w peak power consumption Reduce Peak Demand 65% versus 13 SEER AC system Built in economizer function (Requires Outdoor Thermostat) Single point electric, water and drain connections 24-volt control panel works with any Thermostat with O terminal Water limit switches protection for pumps Removable panels for ease of servicing All stainless steel sump Automatic water quality purge system
FEATURES & BENEFITS
100% Fresh filtered air throughout your building No recirculation of stale air Better indoor air quality Less respiratory CO2 build-up Environmental Friendly No harmful gases are used in our IDEC process. Significantly less energy use versus traditional air conditioning. Humidifies Air Health benefits- Good for Skin and Respiratory System
Advanced Evaporative Cooler Performance Comparison
USA, UT Salt Lake City
ASHRAE 1.0% Design Conditions Dry Bulb (F) Wet Bulb (F) Indoor Room Set (F) Elevation (Feet) 94.8 62.6 75 4226
Cooling Technology
Adiabatic Supply Effectiveness Air F 122% 86% 90% 56 67 66
CFM 2,500 4,500 1,200
BTU's 45,300 33,028 10,245
Equivalent Tons of Cooling
AIR2O IDEC CRS-2500
Breezair Coolerado C-60
5.0
3.6 1.1
HYBRID SYSTEMS
ECONOMIZER, INDIRECT/DIRECT EC AND HEAT PUMP The most complete system for maximum comfort and maximum energy savings The system monitors outdoor conditions and chooses the most economical cooling mode while maintaining indoor comfort Our energy savings increase as a buildings fresh air requirement increases
HYBRID Components
COOLERADO
Executive Summary
Save Green
Our patented cooling technology provides:
50% to 90% more efficiency Only 100 watts of power per ton of cooling Rapid investment payback
48
How Efficient Are We? Western Cooling Challenge
12 HVAC manufactures entered
Challenge -
Beat 2010 DOE standards Coolerado beat the aggressive mark by
an additional 40% First Certified Winner
49
How Coolerado Efficiently Cools
Technology Demonstration
4 1 2 4 3
HOW IT WORKS
1 2 3 5 1
100% FRESH AIR enters the system
2
The AIR IS FILTERED of dust/allergens
3 4
WORKING AIR REMOVES HEAT and is exhausted from the system
5
COOL PRODUCT AIR enters the building with no added humidity
51
Displacement Cooling How To Cool Efficiently
Hot, dirty air, exhausted through the ceiling
Fresh, cool air from Coolerado
52
Energy Efficiency
Coolerado vs. Conventional AC
EER
TEMPERATURE
53
Coolerado Product Line-up
M30
M50 C60
H80
Our solar compatible products provide between 3 to 8 tons and 1,500-3,000 SF of cooling
54
Pre-Cooling Applications
Primary cooling as able
(shoulder seasons or primary season in dry climate)
Pre-cooler in humid
climates No need to remove existing HVAC Substantial energy savings Increase life of existing equipment
55
Las Vegas Summer Design Performance
210
50
55
60
85
45
PSYCHROMETRIC CHART
Normal Temperature
I-P Units
80
85 200 Prepared By: 1.2 Name: Keith Dunnavant 190 Company: Munters/Des Champs Products 85 Tel: 540-291-1111 x4101 W ET 1.1 Fax: 540-291-3333 180 BU LB email: kdunnavant@des-champs.com TE MP Date: 9/23/2007 ER 170
16.0 16.5
AT U
40
HUMIDITY RATIO - GRAINS OF MOISTURE PER POUND OF DRY AIR
75
35
BAROMETRIC PRESSURE: 27.640 in. HG Exhaust Air
30
75
70
130 120
15.5
.8
70 .7
DR
70
25
110 100 90 80
VAPOR PRESSURE - INCHES OF MERCURY
2178 FEET
Supply and Exhaust Airflows are Equal
80
RE
80
- F
1 160 150 140
.9 75
AI R
PO UN
65
65
.6
PE R
-B TU
60
20
65
EN TH AL PY
57.9F
After 90% DEC
55 50 45
50
60
90
.5
60
15.0 VOL
80
70 60 50 40 30 20 10
55 .4 50 45 40 35 30 25 20 .1 .3
- CU UME
15
% 50 75
60 %
.FT. LB PER
10
45
40
35 30 25
5
40
After IEC
35
30%
15
20
30 25
15%
R 8%
EL
IT UMID EH ATIV
DEW POINT TEMPERATURE - F
40
% 50
O/A
% 25
100F DB/65F WB
.2 10 0
1 4 .5
. DR IR YA
1 4 .0
20%
TIVE H 10% RELA UMIDITY
10
10
15
13.0
20
New Wet bulb of 56.1F
4%
6%
13.5
2%
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com
DRY BULB TEMPERATURE - F
1 1 2 2 3
74F/125.2gr
Polymer Tube HX
74F/44.4gr
Dry, Cool Supply Air (Air is Indirect Evaporative Cooled since no water is Added to supply air)
100F/44.4gr Hot outside air (or building exhaust)
Hot outside air 100F/44.4 gr
Water in Stainless Steel Welded Sump
Pump
EPX Indirect Evaporative Cooler (IEC) Cooling Tower Analogy
Heat Out
Air Tunnel
Heat Out
Air In 75 F 85 F
100/65 100/65
Heat In Cooling Coil
Heat In
74/56
80/58
Cooling Tower to Cooling Coil IEC
Air In
EPX Indirect Evaporative Cooler
Heat Load enters water and air directly within CT
Heat Load enters water loop and is rejected at CT
Polymer Tube HX Installed in Packaged AHU Air enters HX Tubes
Mist Eliminator Media installed above HX
Polymer Tube Heat Exchanger
Mills College EPX Units Oakland, California
Sprayed Heat Pipe Indirect Cooler
EVAPORATIVE COOLING
QUESTIONS?
Colvin Engineering Associates, Inc.
HIGH PERFORMANCE DESIGN
