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Optimized Scroll Compressor
for Green Heat Pump Unit
in Retrofit Buildings
Grant Agreement No 308816
FP7-Energy-2012-308816 www.greenhp.eu
The GreenHP Partners
Austrian Institute of Technology,
Project Coordinator
Fraunhofer Insitute for Solar
Energy Systems, Germany
Royal Institute of Technology,
Sweden
European Heat Pump Association,
Belgium
Hesch Schröder GmbH, Germany
Emerson Climate Technologies
GmbH, Germany
AKG Group, Germany
Ziehl-Abegg, Germany
Gränges AB, Sweden
FP7-Energy-2012-308816
Project Info Description: The GreenHP project investigates a new highly efficient heating
system based on high-capacity air/water heat pumps for retrofitting multi-family
houses and commercial buildings in cities.
Targets: The project aims at developing a new system level (interaction with
electric grids, other energy systems and different system components) as well as a
new heat pump unit and component units (refrigerant, compressor, evaporator, fan
and air duct, condenser)
FP7-Energy-2012-308816
Application Heat Pump Unit for large retrofitting buildings in average climate
System: Air/water output up to 100 kW
High Efficiency Prototype Heating capacity 30kW at (A -10/W 55)
Capable of water heating up to 65°C
COP (A7/W55) ≥ 3.5
SCOP* ≥ 3.1
Low GWP refrigerant with Charge target 1 kg GWP < 150
High Efficiency
Reduced Oil charge in the compressor
Air/Water and Water/Water Heat Pump Radiators & Underfloor Heat Distribution
• A/C Scroll: ZR/ZP
• Heating Scroll: ZH**K4E
• Heating Scroll EVI: ZH**KVE
A/W Unit for retrofit require both:
High condensing temperature
Low evaporating temperature
Compressor Design Scroll Design
30 kW Maximum Heating Load at A-10/W55 (-18 °C Evap./58°C Cond.) determines a
Displacement of 96 cc
Optimization elaborated for average climate
0
2
4
6
8
10
12
0
500
1000
1500
2000
2500
3000
-10 -5 0 5 10 15 20
Wo
rkin
g P
res
su
re R
ati
o
En
erg
y (k
Wh
)
Ambient Temp. ( C)
Opt.
Vi Compression Start
Vf Compression End
Heating Energy weighted to operation hours according to EN14825
Compressor working pressure ratio varying with ambient Temperature:
Pressure ratio P.R. = 3.6 results in Optimized BIVR design for SCOP
Compressor Design DC motor Variable Speed
More efficient over a large speed range
Some efficiency decrease at full load
related to inverter losses
Requires special design consideration:
Inverter generates electro-magnetic
interference (EMI)
Necessitates piping circuits to
ensure Oil return
Requires special consideration to
avoid resonances
Oil delivery required for speeds
less than 2400 rpm
DC Motor with higher Efficiency over a wide range
Speed range 1800-7200rpm (30-120Hz)
h%
rpm
Permanent Magnet Motor
DC motor
AC standard motor
2.8
3.1
3.7
2
2.5
3
3.5
4
Fixed speed Fixed Speed EVI Variable Speed EVI
SC
OP
SCOP - Simulation (W55)
12%
17%
Compressor Design Variable Speed and EVI Benefits for SCOP
• EVI (Enhanced Vapour Injection)
Gives +12% SCOP
• with Variable Speed another +17%
SCOP
• (Variable Speed) + (EVI Scroll) give
an increase of +30% in SCOP
EVI Effect VS Effect
Simulation elaborated with R410A
Compressor Design Oil Charge Reduction
Oil charged inside the compressor depends:
Internal oil management inside compressor
Amount mixed with refrigerant and circulating inside the system
GHP compressor targeting 1.0 liter (Similar size standard Scroll have 2.5 liters)
ZHW0961U New design to decrease oil level:
Lower bearing designed to the lowest position inside the shell
Optimize Suction gas port position to decrease the oil pump out from the compressor
Minimum oil required is 1 liter, higher charge will be only for system management
Oil Charge Reduction Impact on Refrigerant Charge
The refrigerant diluted varies with the
operating conditions:
Higher the evaporating temp., higher
is the oil mass diluted
Lower the evaporating temp., lower is
the oil mass diluted
Lower is the gas return temperature
higher is the oil mass diluted
25/40°C 0/56°C -18/58°C Oil Reduction
(g) (g) (g) (%)
2.5 l 258 83 44 -
1.5 l 155 50 27 -40%
1.0 l 103 33 18 -60%
Oil Charge
Refrigerant Diluted in Oil
41
91
258
235
15147
3351
102
162
0
20
40
60
80
-35 -25 -15 -5 5 15 25 35
Co
nd
en
sin
g T
em
pe
ratu
re ( C
)
Evaporating Temperature ( C)
R290 Dilution in the Oil Sump (g)
1.5 liters oil sump
28 91
20
2454
141
155
2.5 liters oil sump
Refrigerant decreases from 83 g to 33 g at rating Conditions (0/56°C)
Maximum R290 diluted 155 g w/ 1.5 liters and 103 g w/ 1.0 liter
ZHW096 Performances
0.00
1.00
2.00
3.00
4.00
5.00
0
10
20
30
40
50
1000 3000 5000 7000 9000
He
at.
CO
P (
-)
He
ati
ng
Ca
pa
cit
y (
kW
)
Speed (rpm)
ZHW096 (GHP)
Comp. Cond. Target Achiev.
Max Heating Capacity (-18/58°C) 30 kW 28.2 kW
COP (A7/W55) (0/56°C) 3.50 3.50
SCOP (EN14825) Avg. Climate 3.1 3.3
Heating capacity and COP
calculated according to EN14825
average climate and based on
compressor performances
R290 allows to reach extreme conditions
10
20
30
40
50
60
70
80
-35 -25 -15 -5 5 15 25 35
Co
nd
. T
em
pe
ratu
re ( C
)
Evap. Temperature ( C)
Heating Range
R290
R410A
R407C
Heating
Variable Speed Scroll
• Range 1800 – 7200rpm
• BPM motor
• High Efficiency
• Drive 18.5kW
• Modbus comunication
R290 Solution
Scroll
EVI
Flow Controls
Scroll
Variable
Speed
Overview Package R290 Solution
Vapor injection Scroll
• Swept volume 96cc
• 30 kW Heating @ -18/58C
• HCOP (A7/W55) = 3.5
• Oil charge ≤ 1.5 liters
System Flow Controls
• Electronic Ref control module
• Refrigerant Circuit controller
• Electronic Alco Exp. Valve
Main Evap SH 4-way valve Actuator
RCC
Main System Control Hesch
Economizer SH
Conclusions
New compressor design developped for GHP Unit
Design Optimized to meet GHP Targets:
Optimized Scroll Design
Variable Speed Technology with BPM motor
Oil Charge Reduction
Results:
Combination R290 and Vapor Injection allow high water temperature at
extreme conditions (Retrofit heating system)
Compressor High Efficiency (SCOP =3.3, HCOP (A7/W55) = 3.50)
Oil charge Reduction by at least 40%
Thank you for your Attention !
Contact Project Coordination
ANDREAS ZOTTL
Engineer
Energy Department
Sustainable Thermal Energy Systems
AIT Austrian Institute of Technology GmbH
Giefinggasse 2 | 1210 Vienna | Austria
T +43(0) 50550-6309 | F +43(0) 50550-6679
[email protected] | http://www.ait.ac.at
FP7-Energy-2012-308816