Air conditioning systems with gas absorption heat pumps Natural gas/LPG fired
Messaggerie del Garda S.p.A. Castiglione delle Stiviere (Mantua), Italy
Saving energy with gas
The former plant
A primary manifold, linked
A necessary change
absorption heat pumps:
The former system, installed
to both the electric chiller
The change from oil to
it’s now possible!
at the “Messaggerie del Garda
and the oil boiler, supplied
natural gas-fuelled boiler
Although certifications confirm
S.p.A.” (a company located
thermal energy with 4 pumps
was necessary.
high performance standards,
in the city of Castiglione delle
for different water circuits,
Taking into consideration
the quality and the
Stiviere, province of Mantua),
one for each floor and one
economic and performance
effectiveness of innovative
supplied heating and cooling
for the keeper’s house.
factors, the engineering “Studio
applications are not easily
to the glass walled 3-floor
Fan coils, provided with clock
Tecnico Associato Zanchi”
demonstrable, because of
building and to the keeper’s
controllers as well as room
has developed a highly efficient
difficulties in measuring overall
house included. For heating
thermostats for temperature
system, thus optimising energy
efficiency. In the following
an oil boiler with a capacity
control, were installed in each
consumption and integrating
case, a comparison between
of 90 kW was installed.
room and supplied heating and
heat pumps and chiller units
a former air-conditioning
For cooling a water-cooled
cooling according to room size.
with low impact on the previous
system and a new highly
electric chiller was installed
water system.
efficient plant was carried out,
in the boiler room, while the
The change from oil to natural
highlighting differences in
evaporative tower was placed
gas fuelled boiler turned out to
energy consumption.
on the flat roof.
be difficult, since the boiler
Messaggerie del Garda S.p.A., Italy
Robur Case History
room did not fulfil fire
Main advantages:
has been carried out,
An excellent choice
prevention requirements.
• hot water up to 60 °C with
since heat pump operating
After a year of complete
A solution ought to be found,
nominal thermal capacity
temperatures are typically
operation (winter and summer
since the air-conditioning
up to 105.9 kW;
lower than those of traditional
included), energy advantages
system was outdated and in need of considerable new investment.
• chilled water down to 3 °C
boilers (60 °C compared
have been proved by a
with nominal cooling capacity
to 70/80 °C).
practical test: electricity and
of 50.7 kW;
Fan coils size turned out
gas bills of different years have
to be adequate for the system
been compared.
• no additional boiler room The technology
is required, since the units
load, although thermal energy
The result confirms the
The research carried out leads
are designed for outdoor
would be provided at a lower
projections of reduction
to an innovative heating and
installation;
temperature.
in energy spending (see table).
Thus, no change to the whole
Electricity consumption is
indoor plant was required.
strongly reduced, while gas
Just a manifold linking the heat
consumption is increased,
cooling system: gas absorption heat pumps. These chiller-heater units are
• reduction in energy consumption and fixed charges; • a better energy management,
able to supply simultaneously
thanks to the use of modular
pumps on the roof top to the
because of the use of gas
heating as well as cooling
units.
boiler room has been installed.
absorption heat pumps
energy in form of hot and cool
Taking into consideration
in winter as well as in summer.
water, using natural gas or LPG
the addition of new units to
According to the profit and loss
as primary energy, with heating
an existing system, the
statement, energy cost savings
efficiency up to 140%.
feasibility of the project has
are estimated at 10,000 €,
Thus, 3 Robur gas absorption
been determined by Mr Zanchi,
a figure confirming the right
heat pumps, GAHP-AR type,
civil engineer. In particular,
choice. Making this decision,
(figure 1 and 2) have been
an evaluation of the capability
the company has been
installed.
of the heat exchange surface
rewarded for its efforts.
Fig.1 - Front view of Robur GAHP-AR gas absorption heat pumps.
Fig. 2 - Robur GAHP-AR gas absorption heat pumps installed on roof with no need of boiler room.
Messaggerie del Garda S.p.A., Italy
Robur Case History
BUILDING DESCRIPTION Floors
nr. 3-floor building: basement, ground level and first floor
Surface
a 800 m2 building plus a 60 m2 keeper’s house
Former heating system
oil boiler, located in the boiler room in the basement
Former system heating capacity
90 kW water-cooled electric chiller unit
Former cooling system
evaporative tower on the roof Former system cooling capacity
30 kW nr. 4 circuits (3 floors building plus keeper’s house) with 4 different pumps
Type of heating and cooling energy distribution
in each room, fan coils provided with room thermostat New unit installed
nr.1 RTAR 180-360 (nr. 3 reversible gas absorption heat pumps GAHP-AR)
Heating capacity of the new system
105.9 kW
Cooling capacity of the new system
50.7 kW
ENERGY SPENDING - YEAR 2004 Electricity consumption per year
24,000 €
referred to the entire electricity consumption of the site
Oil consumption per year
10,000 €
for the supply of the 90 kW oil boiler
Total energy consumption per year
34,000 €
(electric chiller included)
ENERGY SPENDING - YEAR 2005 9,000 €
Electricity consumption per year Gas consumption per year
15,000 €
Total energy consumption per year
24,000 €
referred to the entire electricity consumption of the site (Robur RTAR gas absorption heat pump included) for the supply of the Robur RTAR gas absorption heat pump
SAVING PER YEAR 10,000 €
Saving per year
taking into consideration the variation in energy costs per year as well as variation in heating and cooling power demand per year
GAHP–AR preassembled unit Each module provided with independent circulators
GAS
LEGENDA 1- GAHP-AR unit hydronic kit provided with hydraulic pipes for primary circuit (inertial tank with 4 connections and a 300l capacity, anti-vibration flexible hoses, pressure gauge, flow regulating valve, water filter) 2 - Expansion tank 3 - Circulating water pump 4 - Direct Digital Controller (supplied with pre-assembled multiple unit) 5 - Shut-off valve
Distance max 2 m Ø 2”
Messaggerie del Garda S.p.A., Italy
Robur Case History
RTAR (1) 180-360 OPERATION IN HEATING MODE
(2)
(3)
Heating capacity
kW
G.U.E. heating efficiency based on gas consumption Water flow rate
1.40 3
nominal (ΔT = 10 °C)
m /h
maximum
m /h
minimum
m /h
3 3
Pressure drop at nominal flow rate Outside air temperature dry bulb Inlet water temperature
31
°C
35
minimum
°C
-20
maximum
°C
50
minimum
°C
2
°C
60
kW
50.70
(4)
(5)
G.U.E. cooling efficiency based on gas consumption
0.67 3
nominal (ΔT = 5 °C)
m /h
maximum
m /h
minimum
m /h
7.5
kPa
33
maximum
°C
45
minimum
°C
0
maximum
°C
45
3 3
Pressure drop at nominal flow rate Outside air temperature Inlet water temperature
15 4.2
kPa
OPERATION IN COOLING MODE
Water flow rate
9.12
maximum
Maximal outlet water temperature (ΔT = 10 °C)
Cooling capacity
105.90
minimum Minimum outlet water temperature
8.7 9.6
°C
6
°C
3
BURNER FEATURES Nominal heating input
kW natural gas G20
Gas consumption
natural gas G25 LPG G30/G31
(6)
3
m /h
(7)
3
(8)
73.6 8.01
m /h
9.05
kg/h
5.88
ELECTRICAL DATA Required voltages1 Nominal electrical power
400 V 3N - 50 HZ (9)
standard version
kW
3.21
low noise version
kW
3.3
kg
1.450
standard version
dB(A)
59
low noise version
dB(A)
54
width
mm
3610
depth
mm
1240
height - standard version
mm
1400
height - low noise version
mm
1650
INSTALLATION DATA Weight in operation Sound pressure at 10 meters
Dimensions
(10)
(1)
Values for CC version (with indipendent circulation).
(8)
(2)
Nominal conditions according to EN 12309-2 norm, table 12.
(9)
(3)
Features under nominal conditions: outside air temperature dry/wet bulb 7/6 °C - outlet water 50 °C. (4) Nominal conditions according to EN 12309-2 norm, table 5. (5)
Features under nominal conditions: outside air temperature 35 °C - outlet water 7 °C.
(6)
Lower heating value 34.02 MJ/m3 (9.45 kWh/m3) at 15 °C - 1013 mbar. Lower heating value 29.25 MJ/m3 (8.13 kWh/m3) at 15 °C - 1013 mbar.
(7)
Lower heating value 46.34 MJ/kg (12.87 kWh/kg) at 15 °C - 1013 mbar.
±10% tolerance to allow for different electrical voltage and power absorption of the electrical motors. (10) Free field, frontally, direction factor 2.
Due to continuous product innovation and development, Robur reserves the right to change product specifications without prior notice.
Robur S.p.A. advanced heating and cooling technologies www.robur.com
[email protected] Via Parigi 4/6 24040 Verdellino/Zingonia (Bg) Italy T +39 035 888111 F +39 035 884165