This document describes a case study of an innovative solar heating and cooling system at the F-92 building of the ENEA CASACCIA Research Centre in Rome, Italy. The system uses evacuated tube solar collectors to provide 56% of winter heating needs, with the remaining 44% supplemented by a gas boiler. A phase change material (PCM) storage tank is able to reduce energy dissipation compared to a traditional water tank. The system is also able to provide summer cooling through an absorption chiller. Monitoring shows the PCM tank improves utilization of solar energy from 64% to 76% compared to a traditional tank.

1. XV EUROPEAN CONFERENCE MILANO 7th-8th JUNE 2013 CSG
Latest Technology in Refrigeration and Air Conditioning
Under the Auspices of the PRESIDENCY OF THE COUNCIL OF MINISTERS
“SOLAR HEATING AND COOLING SYSTEMS:
A POSITIVE CONTRIBUTE TO ENERGY AND ENVIRONMENTAL ISSUES”
CASE STUDY: Innovative Solar heating and cooling system with PCM tank at service of F-92 Building of
ENEA CASACCIA Research Centre (ROMA)
XV EUROPEAN CONFERENCE Milan, June 7th 2013
Scientific referents:
Ing. Nicolandrea Calabrese
Ing. Francesco D’Annibale
Ing. Carla Menale
Ing. Paola Rovella
For info: andrea.calabrese@enea.it
www.climatizzazioneconfontirinnovabili.enea.it

2. “Use of solar and environmental heat to air conditioning”
Consumption2

3. F-92 BUILDING FEATURES
Latitude 42°03’N
Longitude 12°18’Est
Climatic
Zone (Italy)
D
Area 381 m2 mq
CASE STUDY: Solar heating and cooling system at service of F-92 Building of ENEA CASACCIA
Research Centre (ROMA)
“Use of solar and environmental heat to air conditioning”
https://maps.google.it/maps/ms?gl=it&ie=UTF8&oe=UTF8&msa=0&msid=103631601450429953584.00047466407d1fa933f1a

4. CASE STUDY: Innovative Solar heating and cooling system at service of F-92 building of ENEA
CASACCIA Research Centre (ROMA)
A NETWORK OF UNDERGROUND PIPING CONNECTS THE HEATING
AND REFRIGERATION STATION TO THE BUILDING
“Use of solar and environmental heat to air conditioning”

5. Heating with Sun…
A) Solar heating:
WINTER TIME: room heating is realized with radiant heating system, powered with low temperature to maximize the
use of thermal solar energy.
Evacuated tubes collectors type all glass
(WINTER: 40-50°C)
(SUMMER: 80 – 110°C)
“Use of solar and environmental heat to air conditioning”

6. Heating with the Sun…using radiant heating system
A) Solar heating:
The highest paviment
temperature depends on
enviroment kind:
Range Tmandata panels: 40 – 50 °C
Dtmaximum panels’s track: 20°C
“Use of solar and environmental heat to air conditioning”

7. Main system’s Components:
A) Solar heating:
Evacuated tube solar collectors:
Technical Data:
-Single collector gross area = 3,75 [m2];
-Solar field gross area = 56 [m2];
-Thermal Power ≈ 25 [kWth].
“Use of solar and environmental heat to air conditioning”

8. A) Solar heating: SYSTEM LAYOUT, during the research activity we analyze the different energy cotributions
FE01
FE07
FE03
FE02
Solar field
Hot tank
Gas boiler
Request of Energy
from building
WINTER WORKING
IN BUILDING
THERMAL CENTRAL
“Use of solar and environmental heat to air conditioning”

9. Winter Monitoring Data: 09 FEBRUARY – 15 APRIL 2012
A) Solar heating:
GAS BOILER
SOLAR FIELD
Energy contribution
Energy contribution of Integration Gas Boiler and Solar Field
09-29 February 2012 01-31 March 2012 01-15 April 2012
kWh Integration
Gas Boiler
kWh Useful
Solar Field
“Use of solar and environmental heat to air conditioning”

10. Winter Monitoring Data: 09 FEBRUARY – 15 APRIL 2012
A) Solar heating:
09 FEBRUARY – 15 APRIL 2012
SOLAR FRACTION
INTEGRATION GAS BOILER: 3.628,0 kWh
SOLAR FIELD: 4.532,0 kWh
09-29 February 2012 01-31 March 2012 01-15 April 2012
Monitoring Thermal Solar Collectors
Solar radiation incident on the solar field [kWh]
Energy Produced by Solar field and used (FE01) [kWh]
Energy produced by the solar field and dissipated by Dry cooler
“Use of solar and environmental heat to air conditioning”
Energy dissipated…

11. “Use of solar and environmental heat to air conditioning”
At the end of our research activity about solar heating and
cooling system for WINTER season we obtained that the energy
required to heat F-92 building was provided for:
- 56 % by solar energy
- 44 % by gas boiler (methane gas)
These results were obtained ensuring COMFORT conditions into
the building.
Winter Monitoring Data: 09 FEBRUARY – 15 APRIL 2012

12. A) Solar heating: obtained indoor environmental temperature
Winter Monitoring Data: 09 FEBRUARY – 15 APRIL 2012
SET POINT
9 - 17 February 2012:
Fixed environment
setpoint
Tmin = 19°C
Tmax = 21°C
19 February - 15 April
2012:
Fixed environment
setpoint
Tmin = 18°C
Tmax = 20°C
Note: set TA01
Tmin = 14°C
Tmax = 16°C
Environment Temperatures [⁰C]
9 - 17 February 2012 Working System CONTINUE
19 February 2012 - 15 April 2012: Working System DISCONTINUOUS (from 7.00 am to 17.00 pm)
“Use of solar and environmental heat to air conditioning”
[Monitoring’s Day]
Environment Temperatures [⁰C]

13. A) Solar heating: Comparision between February 2012 and February 2013
GAS BOILER
Energy contribution
9 - 17 February 2012 Working System CONTINUE
19 February 2012 – 29 February 2012: Working System
DISCONTINUOUS (from 7.00 am to 17.00 pm)
February 2012 February 2013
1975 kWh
(46,5%)
2275 kWh
(53,5%)
Energy contribution
01-28 February 2013 : Working System DISCONTINUOUS
(from 7.00 am to 17.00 pm)
GAS BOILER
SOLAR FIELDSOLAR FIELD
10 - 12 February 2013:
Solar collectors NOT
covered by snow
10 - 12 February 2012:
Solar collectors covered
by snow
“Use of solar and environmental heat to air conditioning”
SOLAR
FRACTION

14. Winter Monitoring Data: 09 FEBRUARY – 15 APRIL 2012
A) Solar heating:
There is Dissipated
Energy….BUT INTEGRATION
GAS BOILER IS USED!!
It would be necessary an
accumulation tank for thermal
energy, DURING WINTER
PERIOD, with a bigger
capacity (experimental
analisys 2012 year with
sensible Accumulation tank of
C=1.500 liters)
NEW GENERATION
ACCUMULATION SYSTEM:
PCM
“Use of solar and environmental heat to air conditioning”

15. PCM (Phase Change Material) Accumulation tank to reduce dissipated energy:
Sensible water accumulation of 3500 l
kJ730005187.43500
outinlwatersens TTcmE
kJ69000533130
,tubeslattubeslat cNE
Latent PCM Accumulation
(PCM S46 TubeICE) of 1000 l
HYDRATED SALTS OF
S89-S7 SERIES placed
in sealed tubes
Cold Water
Hot Water
Solar Field
Control
Unit
Gas
BoilerHot
Water
Tank
“Use of solar and environmental heat to air conditioning”

16. PCM (Phase Change Material) Accumulation tank
“Use of solar and environmental heat to air conditioning”
UNIVERSITA’ DI PADOVA
Dipartimento di Tecnica e
Gestione
dei sistemi industriali

17. PCM (Phase Change Material) Accumulation tank to reduce dissipated energy:
CHARGE PHASE DISCHARGE PHASE
Sensible
Sensible
Sensible
Latent
Temperature of
the phase change
Sensible
Sensible
Sensible
Latent
Temperature of
the phase change
“Use of solar and environmental heat to air conditioning”

18. TRADITIONAL TANK
“Use of solar and environmental heat to air conditioning”
TE07
TE08
TE07
TE08
C = 1500 litres C = 1000 litres
PCM TANK
Comparison Traditional Tank (ONLY WATER) - PCM Tank (HYDRATED SALTS)

19. Comparison Traditional Tank C=1500 litres - PCM Tank C=1000 litres
“Use of solar and environmental heat to air conditioning”
Days of April 2012 and Aprile 2013 (more comparable than days of March because days of April 2012 and days of
April 2013 have medium temperatures more similar than March 2012 and March 2013) have an index FE07/GG
more similar than those of March, respectively 19 kWh/GG and 24 kWh/GG.
If we considere tank contribute to F–92 building heating (TANK_TO_LOAD) we obtain a higher value for 2013 equal
to 16 kWh / GG compared to 13 kWh / GG of 2012.
The contribution of the accumulation to the needs of the building (TANK_TO_LOAD/FE07) was the same: 69% for
2012 and 68% for 2013 (SAME SOLAR FRACTION).
The percentage of utilization of solar energy (TANK_TO_LOAD/FE02) with PCM accumulation amounted to 76%
compared with 64% of the accumulation standard.
where:
• n: days number of the conventional heating period
• T0: environment conventional temperature
• Te: medium extenal daily temperature
APRILE 2012 APRILE 2013
TEMPERATURA MEDIA
PERIODO
13.3 14.3 [°C]
VOLUME ACCUMULO 1500 900 [l]
TEMPERATURA INTERNA
EDIFICIO
20.0 22.0 [°C]
GG] FE07/GG 19 24 [kWh/GG]
GG] TANK_TO_LOAD/GG 13 16 [kWh/GG]
] FE07 1 070 1 556 [kWh]
] FE03 331 503 [kWh]
] FE02 1 159 1 394 [kWh]
] TANK_TO_LOAD 739 1 053 [kWh]
SOLAR FRACTION 69% 68% %
APRIL 2012
TANK VOLUME
INTERNAL BUILDING
TEMPERATURE
APRIL 2013

20. -20
0
20
40
60
80
100
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
00
01
02
03
04
05
06
07
°C
-30
-10
10
30
50
70
90
kWh
FE02
Tank_to_load
TE07
TE08
kW
“Use of solar and environmental heat to air conditioning”
Solid phase PCM
First phase charge during the day: the tank receives
from 8:00 to 12:40 an energy of 56 kWh
There aren’t heat fluxes in or
out from tank
Heat accumulation
due to PCM tubes
melting
20 kWh of thermal energy
are picked up from the
tank
the tank remains
well stratified
Light heat input of PCM
(discharge) which compensates
the heat loss of the tank
Latent heat Sensible heat

21. “Use of solar and environmental heat to air conditioning”
Experimental test of a single PCM Vessel (HYDRATED SALTS)
PCM vessel:
De = 50 mm
L = 1000 mm
HYDRATED SALTS

22. PCM Test Report: EXPERIMENTAL RIG
“Use of solar and environmental heat to air conditioning”

23. PCM Test Report: EXPERIMENTAL RIG
“Use of solar and environmental heat to air conditioning”
Typical test conditions:
• Water velocity in the anulus: 0.2 to 0.4 m/s
• Inlet temperature Ti : 20 to 85 °C
• Pressure P: 1.0 to 1.3 bar
• Temperature ramp gradient: 5 to 600 °C/h
Geometry equivalent to a
subchannel in the real vessel
PCM vessel:
De = 50 mm
L = 1000 mm
Test section:
Di = 60 mm
L = 1000 mm

24. FAST TEMPERATURE RAMP (10⁰C/min)
“Use of solar and environmental heat to air conditioning”
No visible effect on the output
temperature gradient around
the melting temperature
T=46°C
The melting energy is
absorbed and released in
hours and its effect can not be
distinguished from the
thermal capacity of the single
phase material
SLOW TEMPERATURE RAMP (10⁰C/h)
PCM Test Report: EXPERIMENTAL RESULTS

25. PCM: IMPROVEMENTS
“Use of solar and environmental heat to air conditioning”
INCREASE OF PCM CONDUCTIVITY WITH HIGH CONDUCTIVITY FOAMS:
CERAMICS, METALS OR GRAPHITE
AISI 316 SiC (Silicon Carbide)

26. Solar cooling System with Absorption Chiller
B) Solar cooling:
Vacuum Solar
Collector
250 m2
Cold Water
Accumulation
tank 15.000 l
Cold
Water
100 kW
Hot Water
150 kW
CHILLER
SOLAR COOLING system with integration gas boiler and accumulation system for hot and cold water. Idraulic scheme (doc. SYSTEMA S.p.A)
SUMMER PERIOD: coincidence between cool energy request peak and period of maximum availability of solar
energy.
“Use of solar and environmental heat to air conditioning”

27. “Use of solar and environmental heat to air conditioning”
Solar cooling System with Absorption Chiller
B) Solar cooling:

28. SUMMER MONITORING:
B) Solar cooling:
“Use of solar and environmental heat to air conditioning”

29. Main system Components:
B) Solar cooling:
Absorption Chiller
(water – lithium bromide):
Technical Data:
- Cooling Power =18 [kWf];
- Heating Power in =25 [kWt];
Accumulation tank for
cold water:
Technical Data:
- volume 1000 [ L];
Evaporative Tower:
Technical Data:
-Potentiality = 43 [kW]
(Tbu=25,6[°C]; TH2O in=35[°C];
TH2O out=30 [°C]);
-Air Flow = 7.500,0 [m3/h];
-Water Flow = 7.400,0 [l/h]
“Use of solar and environmental heat to air conditioning”

30. Electric Power Absorbed: 48 [W]
Temperature [°C]
T Heat Medium Inlet 88
T Heat Medium Outlet 83
Chilled Water Inlet 12,5
Chilled Water Outlet 7
Cooling Water Inlet 31
Cooling Water Outlet 35
http://www.yazaki-airconditioning.com/fileadmin/templates/img_airconditioning/swf/080925_chiller_absorption_ani.html
B) Solar cooling:
Layout of Absorption chiller water-lithium bromide
“Use of solar and environmental heat to air conditioning”

31. B) Solar cooling:
SYSTEM LAYOUT: during the research activity we analyze the different energy contributions
FE01
FE07
FE03
FE02
FE04 FE05
FE06
Required building
Cold rated output
Heat rate input
SUMMER WORKING
Water/Lithium-bromide Chiller
“Use of solar and environmental heat to air conditioning”

32. B) Solar cooling:
Summer Monitoring Data: 01 June - 15 September 2012
01 JUNE 2012 - 15 SEPTEMBER 2012: Working System DISCONTINUOUS (from 9.00 am to 19.00 pm)
GAS BOILER
SOLAR FIELD
Energy contribution
Energy Contributution of Integration Gas Boiler and Solar Field
01-30 June 2012
kWh Integration Gas Boiler
kWh Useful Solar Field
01-31 July 2012 01-31 August 2012 01-15 September 2012
“Use of solar and environmental heat to air conditioning”

33. B) Solar cooling:
Summer Monitoring Data: 01 June - 15 September 2012
01-30 June 2012
Monitoring Thermal Solar Collectors
01 JUNE – 15 SEPTEMBER 2012
SOLAR FRACTION
INTEGRATION GAS BOILER: 4.657,0 kWh
SOLAR FIELD: 8.909,0 kWh
Solar radiation incident on the solar field [kWh]
Energy Produced by Solar field and used (FE01) [kWh]
Energy produced by the solar field and dissipated by Dry cooler
01-31 July 2012 01-15 September 201201-31 August 2012
“Use of solar and environmental heat to air conditioning”

34. “Use of solar and environmental heat to air conditioning”
At the end of our research activity about solar heating and cooling
system for SUMMER season we obtained that the thermal energy
required by CHILLER to conditionig F-92 building was provided for:
- 66 % by solar energy
- 34 % by gas boiler (methane gas)
These results were obtained ensuring COMFORT conditions into the
building.
Summer Monitoring Data: 01 JUNE – 15 SEPTEMBER 2012

35. B) Solar cooling: obtained indoor environmental temperature
Summer Monitoring Data: 01 June - 15 September 2012
SET POINT
01 June - 15
September 2012:
Fixed
environment
setpoint
Tmin = 22°C e
Tmax = 24°C
Note: TA01
no controlled
01 JUNE 2012 - 15
SEPTEMBER 2012:
Working System
DISCONTINUOUS
(from 9.00 am to
19.00 pm)
T external medium
(09:00 – 19:00)
03/09/2012: 24°C
04/09/2012: 19°C
05/09/2012: 24°C
06/09/2012: 28°C
07/09/2012: 29°C
08/09/2012: 29°C
09/09/2012: 28°C
10/09/2012: 28°C
T external medium
(09:00 – 19:00)
21/07/2012: 31°C
22/07/2012: 29°C
23/07/2012: 25°C
24/07/2012: 27°C
25/07/2012: 30°C
26/07/2012: 32°C
STOP OF SYSTEM
FOR
MAINTENANCE:
21/08/2012
22/08/2012
23/08/2012
26/08/2012
Environment Temperatures [⁰C]
[Monitoring’s Day]
“Use of solar and environmental heat to air conditioning”

36. CONTROL AND MANAGEMENT SYSTEM: BX EINSTEIN
Operative Data and
weather conditions
Management, Control and
Back up PC
Servo motors electric valves
regulation Variable flow pumps
Energy counters
“Use of solar and environmental heat to air conditioning”

37. HIGHLIGHTS OF PRESENTED CASE STUDY
“Use of solar and environmental heat to air conditioning”
ONE OF THE FIVE
BETTER CASE STUDY

38. “Use of solar and environmental heat to air conditioning”
WITHOUT BONUS
Solar heating and cooling: PAYBACK PERIOD
PAYBACK PERIOD RELATIVE DIFFERENT PLACES AND SYSTEM POWER

39. “Use of solar and environmental heat to air conditioning”
WITH BONUS
INTRODUCED BY
D.M. del 28/12/2012
Solar heating and cooling: PAYBACK PERIOD
PAYBACK PERIOD RELATIVE DIFFERENT PLACES AND SYSTEM POWER

40. Our research and development activities:
Thanks for your attention
“Use of solar and environmental heat to air conditioning”