risparmio energetico tramite raffrescamento ......risparmio energetico tramite raffrescamento...
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Titolo del meeting - Roma, 2010
RISPARMIO ENERGETICO TRAMITE RAFFRESCAMENTO ADIABATICO
Roma, 2010speaker: Stefano Ruzzon
Titolo del meeting - Roma, 2010
Energy Savings in direct evaporative cooling
Real application in the Madrid metroand simulated application for offices in Rome
Presented by Stefano RuzzonProduct Manager – Systems for Humidity Control, CAREL Industries S.r.l.
Written by Raul SimonettiApplication Manager – Systems for Humidity Control, CAREL Industries S.r.l.
Titolo del meeting - Roma, 2010
100 kg/h of water atomized into the air provide a cooling effect of 68 kW! (with a consumption <1 kW) by simply changing its status from liquid to gas
SP
EC
IFIC
HU
MID
ITY
[g/k
g]
SATURATION C
URVE (100
%rH
)
60%
rH
10%rH
B
17°°°°C
A30°C
This is a huge amount of energy that can be used to economize on mechanical cooling
Adiabatic cooling with high pressure sprayer
Titolo del meeting - Roma, 2010
Because the contact surface between water droplets and air is increased by atomization (high pressure pump and special nozzles)
For 1 litre of water atomised into droplets with an average diameter of 10 µm, the total surface area of the droplets in contact with air is 600 m².
How does water evaporate?
Titolo del meeting - Roma, 2010
The portion of water evaporated is proportional to the time it remains in contact with air: Time = evaporation length / air speedThe non-evaporated droplets are removed and drained by the drop separator (evaporation efficiency)Es 1.5m, 3m/s ->t=0.5s, eff. appx 95%
Air flow
How quickly does water evaporate?
Titolo del meeting - Roma, 2010
DECDirect Evaporative Cooling
IECIndirect Evaporative Cooling
DEC & IEC in air ducts
Titolo del meeting - Roma, 2010
The exhaust air is humidified/cooled before entering the heat recovery unit; IEC does not humidify the indoor ambient
(IEC: indirect evaporative cooling)
Titolo del meeting - Roma, 2010
Cooling by water evaporation: approx. 680 W/(L/h) of cooling capacity
Implies adiabatic humidification of ambient air (unlike in IEC, the ambient rH is increased)
10 20 30 40 50
60
70
80
90
100
ENTHALPY - KJ PER KILOGRAM OF DRY AIR
30
40
50
60
ENTHALPY -
KJ PER K
ILOGRAM
OF D
RY AIR
SATURATION T
EMPERATURE -
°C
5 10 15 20 25 30 35 40 45 50
DR
Y B
UL
B T
EM
PE
RA
TU
RE
- °C
,002
,004
,006
,008
,010
,012
,014
,016
,018
10% RELATIVE HUMIDITY
20%
30%
40%
50%
60%
70%
80%
90%
HU
MID
ITY
RA
TIO
- G
RA
MS
MO
IST
UR
E P
ER
KIL
OG
RA
M D
RY
AIR
A
B
HU does DEC
Direct Evaporative Cooling
Titolo del meeting - Roma, 2010
Increment ∆∆∆∆W = +1 gv/kgda ���� decrement ∆∆∆∆t ≅≅≅≅ -2.5 °C
Examples:DEC: ∆WHU = +4 gv/kgda � decrement ∆t ≅ -10 °C
IEC:∆WHE = +4 gv/kgda � decrement ∆tHE ≅ -10 ° x 0.50 = -5 °C
Based on the assumption that HE’s efficiency = 50%
But: humidity from DEC goes into the ambient ->must be at an acceptable rHhumidity from IEC goes to exhaust ->can be almost saturated, so usually you can
add more humidity increasing the cooling effect .
Some figures of adiabatic cooling
Titolo del meeting - Roma, 2010
The dryer the intake air, the greater the temperature decrease.
Examples:1)Intake air 30°C 50%rH
humidified to 70%rH -> 26°C
2)Intake air 30°C 20%rH, humidified to 70%rH
-> 19°C
DEC efficiency depends on initial rH
Titolo del meeting - Roma, 2010
Convenient where outdoor air is dry for most of the year (i.e. not in Northern Italy, where IEC is more suitable)IEC= Indirect Evaporative Cooling
Can be used where adiabatic humidification is suitableWhere machinery develop heat (printing factories, textile, data centers…)
Cooling effect: 680 W per L/h of evaporated water
It increases with the water evaporation:With the sprayed water flowAnd with the contact surface water-airSpraying water in minuscule drops increase the contact surface.Example: 1 L of water sprayed in 10-µm drops= 600 m²
DEC: Characteristics
Titolo del meeting - Roma, 2010
Adiabatic air conditioning system at the platforms of Peñagrande subway station, in Camino de Ganapanes street, Madrid.
The aim of this solution is to provide more comfort, cooling the environment using water as a “source of power”, because it’s considerably more economic than traditional cooling systems (direct expansion) as it consumes less power.
Adiabatic cooling tested in Madrid underground
Titolo del meeting - Roma, 2010
In summer time, ventilation cannot fully compensate for the indoor heat loadsdue to trains (electrical motors) and people waiting.
In August, the outdoor conditions reach 35 °C, up to 40 %rH
Solutions:Chiller + cooling coil, ORDEC
Chiller + cooling coil : more expensive than DECDEC: lower cost + savings from energy saving
DEC in Peñagrande: the idea
Titolo del meeting - Roma, 2010
For evaluating the benefits of the DEC solution, a comparative installation has been built in two subway stations along the same line, so that they have the same outdoor conditions, same number of trains, passengers, etc:
Penagrande station:equipped with DEC and monitored
Illustracion station:monitored only
2 station for comparative test
Titolo del meeting - Roma, 2010
2 platforms
2 AHUs to compensate the indoor heat loads:
• Each rated 90,000 m³/h (as per design), 100% outdoor air
• No cooling coil
DEC in Peñagrande station (Madrid subway)
Titolo del meeting - Roma, 2010
Spraying rack and drop eliminator
Titolo del meeting - Roma, 2010
Pump and control
Titolo del meeting - Roma, 2010
Cabinet with high press. pumpWith control system and VFD
(100 to 5.000 litres/hr)
Spraying nozzle(in rack) Rack to spray in duct/AHU with
double electrovalves& AISI304 drop separator
High-pressure water atomizercertified according to VDI6022
Titolo del meeting - Roma, 2010
Runs on demineralised water:
Up to 50 µS/cm0-25 ppm CaCO3
Sprayed water pressure: 20-80 bar
Water flow modulated by VFD upon demand
Specific power consumption: 5-10 W/(L/h) of water
External R.O. system included
Hygienic compliance for use in AHU also for
hospitals (local laws/norms apply):
Atomizer: characteristics
Titolo del meeting - Roma, 2010
High-pressure atomizer in each AHU
Water flow controlled by a humidity probe downstream in the duct
Brings outdoor air from 35 °C, 40 %rH to 27 °C, 70%rH
Real outdoor air flow: 71,818 m³/h per AHU
Evaporated water: 277 kg/h per AHU
The monitoring system acquires:
• Outdoor air: temperature and humidity
• Discharging air: temp. and hum. (end of duct)
• Ambient air: temperature and humidity
DEC in Peñagrande: structure
Titolo del meeting - Roma, 2010
COMPARATIVA ESTACIONES 4/09/06
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
90,00
12.3
0
13.0
0
13.3
0
14.0
0
14.3
0
15.0
0
15.3
0
16.0
0
16.3
0
17.0
0
17.3
0
18.0
0
18.3
0
19.0
0
19.3
0
20.0
0
20.3
0
21.0
0
21.3
0
22.0
0
22.3
0
23.0
0
23.3
0
HORA
ºC Y
%H
R
Tª EXT. PEÑAG. Tª EXT. ILUST. Tª AMB. PEÑAG. Tª AMB. ILUST. Tª IMP. PEÑAG. Tª IMP. ILUST.
HR EXT. PEÑAG. HR EXT. ILUST. HR AMB. PEÑAG. HR. AMB. ILUST. HR IMP. PEÑAG. HR IMP. ILUST.
El ecpa S.L.Instalaciones y Control
Data from a typical day in the stations
Titolo del meeting - Roma, 2010
COMPARATIVA ESTACIONES 4/09/06
0,00
10,00
20,00
30,00
40,00
50,00
60,00
70,00
80,00
90,00
12.3
0
13.0
0
13.3
0
14.0
0
14.3
0
15.0
0
15.3
0
16.0
0
16.3
0
17.0
0
17.3
0
18.0
0
18.3
0
19.0
0
19.3
0
20.0
0
20.3
0
21.0
0
21.3
0
22.0
0
22.3
0
23.0
0
23.3
0
HORA
ºC Y
%H
R
Tª EXT. PEÑAG. Tª EXT. ILUST. Tª AMB. PEÑAG. Tª AMB. ILUST. Tª IMP. PEÑAG. Tª IMP. ILUST.
HR EXT. PEÑAG. HR EXT. ILUST. HR AMB. PEÑAG. HR. AMB. ILUST. HR IMP. PEÑAG. HR IMP. ILUST.
El ecpa S.L.Instalaciones y ControlrH in DUCT
rH after mix indoor
T in second station (no DEC)
T in station with DEC
Reading the data
Titolo del meeting - Roma, 2010
In the period 15/july/2006 to 15 sept/2006, the temperature in the Penagrande station
was 3.4°°°°C (=6,1°°°°F) colder than in the Illustration station, not equipped and used for
comparison
When compared to traditional systems using direct expansion, water coolers with
compressors, roof-tops etc, the fundamental advantage of the adiabatic cooling
system is its low power consumption.
The test in Madrid was considered positive:
today 13 subway stations of Metro are equipped with DEC and more will be
equipped as budget will allow for.
Average results during 2 months of test
Titolo del meeting - Roma, 2010
146,42 kW5,54 kWElectric power [b]
EURO 7116EURO 297Running cost [d + f]
Not applicableEURO 28Water cost [f = e x 0,95 EURO/m³]
Not applicable29850 litresSprayed water [e]
EURO 7116EURO 269Cost of electrical energy[d= c x 0,18 EURO/kWh]
39535 kWh1496 kWhElectric energy [c = a x b]
270 hrs270 hrsDuty (June 7-25, 2006) [a]
Equivalent chiller
(EER=2.5)
DEC
(based on real data)
Parameter
DEC in Peñagrande:savings
Titolo del meeting - Roma, 2010
London Underground – “Cooling the tube” projectDucted system with humiFog at Charring Cross stationHumiFog ventilated units at Colliers Wood station
The test is considered positive; a test with wet media was discarded as problematic
Another test in London…
Titolo del meeting - Roma, 2010
Cabinet with high press. pumpWith control system and VFD
(100 to 5.000 litres/hr)
Spraying nozzle(in rack) Rack to spray in duct/AHU with
double electrovalves& AISI304 drop separator
High-pressure water atomizercertified according to VDI6022
Titolo del meeting - Roma, 2010
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120 140 160 180 200
water flow kg/h
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120 140 160 180 200
water flow kg/h
High pressure pump:
combining variable speed (with VFD) and staging(electrovalves)to obtain acontinuous modulation in a wide range with:• no recirculation• no wetting • no waste• less wear out
This linear response diagram results from the combination of speed control AND staging
Precise modulation of water flow
Titolo del meeting - Roma, 2010
• no water recirculation (VFR)• demineralized water (no salts)• no chemical biocide that accumulates in the ambient• all stainless steel components including droplet separator• complete automatic water drains and flushing cycles obtained with inlet + outlet electrovalves
Hygienic safety is needed for this application
Titolo del meeting - Roma, 2010
Rome: a simulation of DEC in an office
A simulation of DEC with the same principle has been made for Rome, with its climatic situation represented in this chart
Titolo del meeting - Roma, 2010
Conditions considered:
Office for 40 persons
Set point: 21 °C, 50 %rH
Air quality: IDA 1 (pure, as per EN 13779:2004)
Supply temperature: 18 °C (point I of chart on slide 12)
Ventilation: 6-20 every day, all year long
1 kWh = 0.18 EURO
1 m³ of mains water= 1.28 EURO
Comparison between:
• DEC: high-pressure atomizer with saturation efficiency= 90%
• Chiller + cooling coil: EER= 2.5
Rome: DEC in AHU for an office (estimate)
Titolo del meeting - Roma, 2010
Main characteristics:High-pressure atomizer for DECFree cooling by Variable Air Volume to compensate the internal heat loads
Rome: DEC for office - AHU
Titolo del meeting - Roma, 2010
R R
ASHRAE PSYCHROMETRIC CHART NO.1NORMAL TEMPERATURE
BAROMETRIC PRESSURE: 101,325 kPa
Copyright 1992AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR- CONDITIONING ENGINEERS, INC.
SEA LEVEL
5
10
15
20
25
30
10 15 20 25
DR
Y B
ULB
TE
MP
ER
AT
UR
E -
°C
,002
,004
,006
,008
10% RELATIVE HUMIDITY
20%
30%
40%
50%
60%
70%
80%
90%
HU
MID
ITY
RA
TIO
- G
RA
MS
MO
IST
UR
E P
ER
KIL
OG
RA
M D
RY
AIR
R R
ASHRAE PSYCHROMETRIC CHART NO.1NORMAL TEMPERATURE
BAROMETRIC PRESSURE: 101,325 kPa
Copyright 1992AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR- CONDITIONING ENGINEERS, INC.
SEA LEVELD1
No free cooling, NO energy saving;
mechanical cooling at Gvent (min G
E),
eventually de-humidification
D2D3
Region U4
Heating + evap.+
free cooling
U1U2
Partial free cooling +
evaporative cooling
U3Full free cooling +
evaporative cooling
hSET
hI
SET
hE,min
I
U1: No free cooling, NO energy saving; mechanical cooling at Gvent (min GE), then evaporative cooling
D2: partial free cooling + de-humidification
D3: full free cooling + de-humidification
G I: sup
ply flo
w
G E: ou
tdoo
r air flo
w
G vent: min G
E
D4 (not shown, left of D3):de-humidification +heating + free cooling
Rome: DEC + free cooling
Titolo del meeting - Roma, 2010
D2
D3
D4
D1
U1
U4U3 U2
Each dot represents a condition of the outdoor air
Rome: Climatic conditions
Titolo del meeting - Roma, 2010
The simulation has been performed thanks to a programme developed by the University of Padova, Department of Technics and Management, to estimate the energy savings with the usage of DEC or IEC techniques. The programme uses a climatic database with 1-hour resolution available for most cities in the world; the inputs are setpoint, number of people and other thermal loads, efficiency of evaporation and so on.
DIPARTIMENTO DI TECNICA E GESTIONE
DEI SISTEMI INDUSTRIALIFACOLTÀ DI INGEGNERIA - UNIVERSITÀ DI PADOVA
How the simulation has been made
Titolo del meeting - Roma, 2010
simulation program inputs
Ambient air temperature tA [°C] 22,0Ambient air relative humidity ϕΑϕΑϕΑϕΑ [%] 50
Ambient air humidity ratio xA [kgv/kga] 0,00822 8,22Ambient air enthalpy hA [kJ/kga] 43,0
City (TRY) Venice
Inlet air temperature tI [°C] 20,0Inlet air humidity ratio xI [kgv/kga] 0,00821 8,21
Inlet air enthalpy hI [kJ/kga] 41,0
Persons 10Persons Latent Load [W/pers] 50
Other Latent Load [kW] 0,0Total Latent Load Gv [kgv/s] 0,00020Total Latent Load Plat [kW] 0,5
Persons Sensible Load [W/pers] 75Other Sensible Load [kW] 30,00
Total Sensible Load Psens [kW] 30,8Ventilation (external) Air Flow Gvent [l/(s pers)] 7
Optimize External Air Flow GE ? 1,00Ventilation (external) Air Flow Gvent [m3/h] 252Ventilation (external) Air Flow Gvent [kga/s] 0,086
Specific Latent Load ∆xsp [kgv/kga] 0,00238Inlet Air Flow GI [m3/h] 44.914
Ventilation / Inlet Air Flow Ratio Gvent/GI 0,01Outlet / External Air Flow Ratioαααα = GO/GE 0,90
HU Saturator Efficiency (nominal) ηηηηHU 90%EER chiller 2,9
ηηηη electric plant 40%
Initial month Final monthWorking period March October
Start TimeStop TimeWorking time 6,00 20,00
AMBIENT AIR CONDITIONS
EXTERNAL AIR CONDITIONS
INLET AIR CONDITIONS
OTHER INPUTS
Titolo del meeting - Roma, 2010
110,4Electric energy used for DEC [e]
1590Annual saving [g – h]
14Sprayed water: 11039 litres/yr @ 1.28 EURO/m³ [h](*)
1604Saved energy [g = f x 0.18 EURO/kWh]
EURO/yearCost saving
8914 kWh
ca. 8.9 t of CO2
Saved electric energy [f = d - e]
9024Electric energy saved by the chiller [d = c / EER]
22561Free cooling + DEC net [c = a – b]
3667Energy for de-humidifying the outdoor air [b]
26228Of which by free cooling + DEC [a]
38407Total load (heat gains + ventilation)
kWh/yearLoads
(*) approx. 30 liters/day, like a shower …
Rome: DEC for office - savings
Titolo del meeting - Roma, 2010
DEC is convenient, because it cools the air by exploiting the latent heat of water evaporation (680 W/[L/h])
DEC by high-pressure water sprayer uses 5-10 W/(L/h), approx. equal to 4% the power of an equivalent chiller + cooling coil
Less pollution: each kWh saved corresponds to 1 t of CO2 not introduced into the atmosphere (average value)
DEC is convenient where adiabatic humidification is suitable and where outdoor air is warm and dry for most of the year not in Northern Italy, where IEC is more suitableIEC= Indirect Evaporative Cooling
DEC - conclusions
Titolo del meeting - Roma, 2010
Sprayer for
• Winter humidification in AHU
• Direct Evaporative Colling (DEC) in summer
Can e save more energy?Can e save more energy?
Evaporative cooling summary: DEC
Titolo del meeting - Roma, 2010
25°C
50%rH
25°C,
50%rH
35°C, 40%rH
31°C, 36%rH
29°C, 56%rH
30’000m3/h
Power saving: 58kW
Heat exchanger: ∆P = 400Pa
Di=1.7x1.7x1.5m; spacing 8,5mm
Efficiency = 58%
Heat recovery to save energy, but…
Can e save more energy?Can e save more energy?
Titolo del meeting - Roma, 2010
25°C
50%rH
18°C, 100%rH
100kg/h
35°C, 40%rH
28°C, 55%rH
25°C, 70%rH
30’000m3/h
Power saving: 100kW
Heat exchanger: ∆P = 400Pa
Di=1.7x1.7x1.5m;spacing 8,5mm
Efficiency = 58%
Energy saving = 100 – 58 = 42 kW
by
spraying 100kg/h water
0,95 kW electric power ONLY!
Cooling coil is 42kW smaller
Chiller has 42kW less capacity!
Indirect Evaporative Cooling (IEC)
Titolo del meeting - Roma, 2010
Thanks to the use of demineralised water, maintenance on the high-pressure water sprayer is limited to its pump:
change the oil every 2,000 hours of dutychange the gaskets and valves every 4,000 hrs of duty
Dedicated warnings are generated every 2,000 hours
Why using a high pressure sprayer instead of an air washer or wet media?(1) Capacity modulation and (2) maintenance costs !!!
Water sprayer: maintenance
Titolo del meeting - Roma, 2010
ADIABATIC WITH RECIRCULATION ADIABATIC WITHOUT RECIRCULATION VDI 6022-2006: OPERATIONS
14 days
1 month
3 months
6 months
12 months
24 months
14 days
1 month
3 months
6 months
12 months
24 months
Complete hygienic inspection by a specialist
� �
Control of contamination, damage, microbial proliferation and corrosion: cleaning and repairs
� �
Check for condensate in the humidification section
�
Bacterial count on the water: if > 1,000 CFU/ml (1 CFU/ml for Legionella pneumophila), wash with disinfectants, rinse, dry; analysis of supply water quality
� Recirculated
water
� Supply water
Exception: isothermal
Check the condensate drain circuit from the droplet collector tank or the cylinder in isothermal appliances
�
VDI 6022: maintenance of humidification sectionsystems with vs. without recirculation
Titolo del meeting - Roma, 2010
ADIABATIC WITH RECIRCULATION ADIABATIC WITHOUT RECIRCULATION VDI 6022-2006: OPERATIONS
14 days
1 month
3 months
6 months
12 months
24 months
14 days
1 month
3 months
6 months
12 months
24 months
Check the recirculating pump for contamination and fouling in the water lines and check the condition of the filters: clean the pump water circuit.
�
Inspect the atomiser nozzles for fouling: clean or replace the nozzles
� �
Check the limit probe � Functional test on the conductivity meter: calibration
�
Functional test on the sterilisation device: repair
�
Check the automatic shutdown mechanisms
�
Clean the humidifier if shut down for more than 48 hours: wash with detergents/disinfectants, rinse and dry
When necessary
VDI 6022: maintenance of humidification sectionsystems with vs. without recirculation
Titolo del meeting - Roma, 2010
ADIABATIC WITH RECIRCULATION ADIABATIC WITHOUT RECIRCULATION
VDI 6022-2006: OPERATIONS
14 days
1 month
3 months
6 months
12 months
24 months
14 days
1 month
3 months
6 months
12 months
24 months
Droplet separator and flow rectifier: check for contamination, damage, fouling and corrosion. If fouled, remove and clean the separator and check the condition of the duct downstream of the separator.
�
� (not required
by the standard but
recommended)
NUMBER OF MONTHLY
OPERATIONS 2 4 1 1 1 1 0 2 2 3 0 1
TOTAL NO. OF MONTHLY
OPERATIONS1 2 6=4+2 7=6+1 8 9 10 0 2 4 7 7 8
1 This is the number of preventive maintenance operations that must be completed in the month in question: this is the total of the operations
indicated with the “�” in the corresponding column + the operations indicated in the columns to the left of this (more frequent) . Example for recirculating adiabatic humidifiers: every 6 months the operation of the sterilisation device must be checked (“6 months”) + the operation in the “3 months” column + the 4 monthly operations + the 2 monthly bacteriological analyses, giving a total of 8 operations every 6 months.
VDI 6022: maintenance of humidification sectionsystems with vs. without recirculation
Titolo del meeting - Roma, 2010
VDI 6022 “Hygiene requirements for ventilation and air-conditioning systems and -units”ASHRAE, “ASHRAE 12-2000 Guidelines – Minimizing the Risk of Legionellosis Associated
with Building Water Systems”AS/NZS 3666.1:2002, “Air-handling and water systems of buildings—Microbial control”Subdirección General de Sanidad Ambiental y Salud Laboral, “GUIA TÉCNICA PARA LA
PREVENCIÓN Y CONTROL DE LA LEGIONELOSIS EN INSTALACIONES”Renato Lazzarin, Luigi Nalini, “Air humidification - Technical, health and energy aspects”,
CAREL SpAEN 13779:2004 “Ventilation for non-residential buildings – Performance requirements for
ventilation and room-conditioning systems”Vattenfall AB, “LIFE-CYCLE ASSESSMENT”
(http://www.vattenfall.com/www/vf_com/vf_com/Gemeinsame_Inhalte/DOCUMENT/360168vatt/386246envi/2005-LifeCycleAssessment.pdf#search="life%20cycle%20emissions%20-vfcom")
Bibliography
Titolo del meeting - Roma, 2010
Thank you
Stefano Ruzzon
Product ManagerSystems for Humidity Control, CAREL Industries S.r.l.