Performance data
Increased performances with Hygroove
Sapa asked the Danish Technological Institute to measure the heat transfer
performances of three of its tubes for fin and tube heat exchangers. The heat
transfer coefficient of 9.52mm precision drawn tube, Hygroove tube with straight
grooves and Hygroove tube with helical grooves have been measured using a
special test set-up1. Based on the tube heat transfer coefficient values, Sapa
calculated with a mathematical model the heat transfer coefficient of the overall
heat exchanger.
Data show that both Hygroove tubes give higher performance results than
smooth bore tubes. In particular, compared to precision drawn tube, Hygroove
helical tube shows:
1. up to 108% higher heat transfer coefficient of the tube,
2. up to 8% higher heat transfer performances of the overall heat exchanger.
Sapa is the world leader in aluminium solutions - a new company that
has joined the aluminium extrusion businesses of Sapa and Hydro.
Together, we are shaping a lighter future through a global reach and
local presence within extrusions, building systems, and precision
tubing. We have 23,000 employees in more than 40 countries, and
our headquarters are located in Oslo, Norway.
ABOUT SAPA’S PRECISION TUBING BUSINESS AREA
Overall heat exchanger heat transfer
performance
Tube heat transfer performance
Tube heat transfer
coefficient (HTC) at
massflux of 200 kg/m2s
[W/m2s]
Relative
improvement
compared to PDT [%]
Calculated overall heat
exchanger heat transfer
coefficient [W/m2s]
Relative
improvement
compared to PDT [%]
PRECISION DRAWN
TUBES
5000
-
576
-
HYGROOVE - Straight
6800
+36%
597
+4%
HYGROOVE - Helical
10400
+108%
618
+8%
11000
Sapa Precision Tubing is the clear market leader in the field of
providing aluminium solutions for heat transfer applications. Our
company has 30 years of experience supplying the automotive and
the HVAC&R (heating, ventilation, air-conditioning and refrigeration)
industries.
Beside heat transfer applications, Sapa‘s Precision Tubing Business
Area supplies aluminium extruded tubes and welded tubes for gas/
fluid, structural and solar thermal applications. In addition, we also
supply niche markets (railway, heavy vehicles, geothermal and other
segments) where our technological competence and innovative
products can serve our customers.
Sapa Precision Tubing has about 2,000 employees at 17 plants and
product and process development centers, serving local and global
customers all around the world.
TEST CHARACTERISTICS
1
Aluminium Tube Solutions
Heat transfer coefficient [W/m2K]
10000
(3) Helical Hygroove
9000
•
Tubes: OD x WT = 9,52 x 0,6 mm, 6m straight
test tube length with refrigerant inside
8000
•
(4) Straight Hygroove
7000
6000
(1) Aluminium Smooth
5000
4000
Tube in tube (coaxial) test set up with counter
•
Refrigerant R410A
•
Evaporating temperature at 10 ° C
•
Mass flux between 125 -250 kg/m2s
•
Inlet vapour quality of 0.1 and outlet vapour
•
Esther oil: Oil Circulation Rate (OCR) approximately 1% of mass flow
2000
100
150
200
for Fin and Tube Heat Exchangers
flow. Water on outer side of test tube
quality of 0.9
3000
SALES CONTACT:
EUROPE
Bjørn Vestergaard
T +45 73 71 14 18
E bjorn.vestergaard@sapagroup.com
CHINA
Shen Yang
T +86 512 6283 6368
E yang.shen@sapagroup.com
INDIA
Sajith Jose
T +91 80988 60888
E jose.sajith@sapagroup.com
MIDDLE EAST
Adil Atiser
T +45 73 71 12 21
E adil.atiser@sapagroup.com
JAPAN AND KOREA
Akira Yamakawa
T +86 512 6283 5685
E akira.yamakawa@sapagroup.com
NORTH AMERICA
Anders Sorensen
T +1 321 638 1185
E anders.sorensen@sapagroup.com
SOUTH AMERICA
Rodolfo Bocato
T +55 11 4025 6768
E rodolfo.bocato@sapagroup.com
250
Massflux G [kg/m s]
2
www.sapatubing.com
© Sapa 2013 Version 1.1. December 2013
Drop-in solutions for copper replacement
why
When converting from copper to aluminium or
expanding the use of aluminium for additional
applications, there are several technical challenges
that have to be overcome.
Why all-aluminium fin and
tube heat exchangers?
The heating, ventilation, air conditioning and refrigeration HVAC&R
industry has been using mechanically assembled copper tubes and
aluminium fin solutions for years. Replacing the copper tubes with
aluminium tubes provides tangible benefits:
1. Price per meter
2. Weight per meter
The price of aluminium raw material is one-fourth the
price of copper1. This will definitely impact your bottom
line.
Aluminium tubes are 35% lighter than copper, for
equivalent burst pressure.2 This improves system
weight significantly.
3. Corrosion resistance
4. Performance
Corrosion can manifest itself in two ways. First, it
can lead to reduced performance of the system, due
to galvanic corrosion between tube and fin. In allaluminium heat exchangers, due to a closer galvanic
balance between fin and tube, this will occur far later
than in a mixed metal - copper tubes and aluminium
fins - unit. Of course, care has to be taken in aluminium
alloy selection, so that the tube will be more noble than
the fin material.
Second, corrosion can lead to tube leakages. With
proper alloy selection, tube failures will not occur.
However for all-aluminium heat exchangers in outside
units, Sapa recommends zinc coating of the tubes
as extra protection against the possible effects of
aggressive environments.
In an all-aluminium fin and tube heat exchanger, the
tubes have the same thermal expansion coefficient
as aluminium fin stock. The bond between tube and
fin will be constant regardless of temperature, thus
ensuring better heat transfer. In addition, aluminium has
less spring-back effect than copper, meaning a better
bond between the tube and fin during expansion.
Precision drawn tubes
straight inner
grooved tubes
Hygroove
Sapa has 30 years of experience supplying the
automotive and the HVAC&R industries with
solutions and our Applications & Development
engineers will support you in every step of the
project. From selecting the right dimensions and
alloys for your application to providing in-depth
knowledge of metallurgy, joining methods and
brazing, Sapa has the experience and capability to
be your partner.
helical inner
grooved tubes
Hygroove
The standard drop-in solution for
copper replacement
Improved heat transfer with
inner grooves
The highest performance in heat
transfer
Precision drawn tubes are the light solution for
standard heat exchangers manufactured with
mechanically expanded round or oval tubes.
The manufacturing process, which includes
extrusion, drawing and annealing, guarantees
narrow tolerance and a superior surface finish of
the tubes. Precision drawn tubes represent an
economic alternative to copper.
Hygroove is an internally enhanced aluminium tube
for high-fin density condensers and evaporators.
The inner grooves improve heat transfer, offering
higher efficiency by more compact design.
Additional Zinc coating layers are available to
further increase corrosion resistance, which makes
this product a high performing tube. Different
grooves depth and geometry satisfy the specific
regional requirements and refrigerants in use.
The inner grooves are following a helical pattern
and have been optimized to improve heat transfer.
The improvement in heat transfer coefficient of
the tube is two times what can be achieved with
traditional smooth bore tubes3. This increased
efficiency can help achieve a more compact
design of the heat exchangers and a reduction
in refrigerant load. Different grooves depth and
geometry satisfy the specific regional requirements
and refrigerants in use.
3
Choosing aluminium solutions from Sapa is more
than choosing the price tag. Sapa provides more
than the metal: processability in the customers
process and performance in the field are also part
of what you get with Sapa as your supplier.
Additionally Sapa‘s Research and Development
department ensures you will remain at the forefront
of technology and continue having the most cost
efficient and effective solutions in the market.
Refer to the performance data on the backside of this brochure
Our tube range at a glance
5. Recyclability
Aluminium recycling is important for resource
preservation. There is no need to separate different
materials in an all-aluminium heat exchanger, thus
making recycling easier.
Based on avergae LME price from January 1 to November 29, 2013. Primary aluminium, 3-months buyer 1.854 $/kg.
Copper grade A, 3-months buyer 7.332 $/kg. Ratio copper/aluminium price=3.96.
4
BURST PRESSURE 4
[PSI]
GROOVES
DEPTH [mm]
NUMBER OF
GROOVES
GROOVES
ANGLE [°]
COATINGS
KEY FEATURES
AVAILABILITY
ALLOYS
Precision drawn
tube
Precision drawn tube with
smooth inner surface
• Easy to form and bend
• Low cost and weight
• Level wound coils
• Cut to length
HA3003,
HA9158,
HA9134M
Standard range:
5 to 22
Other OD upon
request
Standard range:
0.35 to 2
Other WT upon
request
-
-
-
-
-
Zinc coating
Hygroove straight grooves
Precision drawn tube with
inner grooved surface
• High heat transfer efficiency
• Easy to form and bend
• Low cost and weight
• Level wound coils
• Cut to length
HA9158,
HA9134M
7
7.1
7
9.52
9.52
0.47
0.50
0.50
0.70
0.50
130
145
147
152
106
1900
2000
2100
2150
1500
0.28
0.25
0.30
0.30
0.30
45
40
38
50
50
-
Zinc coating
HA9158,
HA9134M
7
7
7
9.52
9.525
10
0.47
0.50
0.45
0.68
0.50
0.70
130
147
131
147
106
144
1900
2100
1900
2100
1500
2000
0.16
0.16
0.23
0.30
0.18
0.25
48
55
48
40
40
40
18
25
20
20
18
20
NA
Hygroove helical grooves
For outside diameter of 9.52mm and burst pressure of 123 bar, aluminum tube weight is 46g/m (tube WT=0.6mm,
density=2.73g cm3). Copper tube weight is 72g/m (tube WT=0.28mm, density= 8.9g/cm3).
OUTER
DIAMETER [mm]
BURST PRESSURE 4
[bars]
PRODUCT
DESCRIPTION
1
2
Zinc coating and clad
layers for round tubes
WALL
THICKNESS
[mm]
Precision drawn tube with
inner grooved surface
Calculated values for alloy HA9158. Temper O
• Very high heat transfer
efficiency
• Easy to form and bend
• Low cost and weight
• Level wound coils
• Cut to length
For heat exchangers operating in aggressive
environments, Sapa strongly recommends the
addition of a zinc coating to the tubes. This
additional layer will provide the tubes with
increased corrosion protection and will improve
lifetime compared to the equivalent bare tube. This
zinc coating is available on smooth bore tubes, and
straight inner grooved tubes.