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* First presented at the REHVA - Annual Meeting Seminar "HVAC sector challenges ahead" on 04.04.2017
3D-Printing
(additive manufacturing) has been a paradigm change for the manufacturing
industry especially on the last decade. It has basically been used as a hobby
tool and for the production of non-functional parts to aesthetically control
the design, it is also being used for manufacturing functional parts in the
prototyping phase in a very wide range of industrial fields. As the technology
has been developed, additive manufacturing has also been used for production of
fully functional parts, even in the aerospace industry. There are many
organizations and collaborations to study the technology and environmental
impact of additive manufacturing and build the industrial standards. It is
expected that additive manufacturing will take the place of today's industrial
production methods and affect value chains to a significant extent within the
next decades, along with the development of relevant design theory and tools.
Especially, the future of industry shaped upon “cloud manufacturing” and “mass
customization”, relies on additive manufacturing the most. The Hype Cycle of
Gartner on emerging Technologies reports that enterprise 3D printing is to be
used in the main stream industry in the following 2–5 years.
One of the
areas that additive manufacturing will have a significant impact will be the
Architecture, Engineering and Construction (AEC) industry. The hot topic about
building technology is integrated design that includes the overall design of a
building including all of its components in harmony. This was also a hot topic
in the old times. Two examples of integrated design solutions of the past are
Ondol and Hypocaust systems. Ondol system is an example from the eastern world
that was used in the traditional houses of Korea for cooking and underfloor
heating simultaneously. Hypocaust is an example of integrated design of
Greco-Roman World, which is a kind of central heating system in a building that
produces and circulates hot air below the floor of a room, and may also warm
the walls with a series of pipes through which the hot air passes. The hot air
carried by the pipes can warm the upper floors as well [1].
The
hypocaust system was built by bricks, which is a kind of additive manufacturing
process (Figure 1). Therefore the Hypocaust system
can be assumed as the ancestor of the near future’s buildings, which will be
constructed in a holistic approach. The buildings of the future will be
constructed at once by additive manufacturing with all of their architectural
elements, HVAC systems, and sanitary systems, as their ancestors were built.
Figure 1.
A Hypocaust system construction. [2]
An early
example on additive manufacturing of buildings is by the group of Khoshnevisk
[2] in 2004. They named the method as “Countour Crafting” which is an additive
manufacturing application for building construction. The method is said to be
most useful for emergency reconstruction by disaster and relief agencies
working in third world nations devastated by earthquakes, floods, other natural
disasters and war. However, they worked on developing technologies on this subject
including a project (together with NASA) on using the additive manufacturing
for building space colonies. They also mention about the integrated design
needs and the possibility of manufacturing HVAC equipment together with the
building itself.
More
recently, in 2015, World’s first 3D printed apartment building was constructed
in China. In 2016, world’s first 3D-Printed and fully functional office building
was constructed in Dubai. All of the furniture of the office were also printed.
There are many other examples of 3D printed houses and structures around the
world. Some are modest to utopian shelters and the other are fully functional
buildings for different purposes. There are also many interesting and/or
functional designs waiting to be built [3]. What is more, some of those are designed
to be constructed in a modular way which is a very efficient method of using
additive manufacturing. Factories having a number of 3D printers for this
purpose may be set up and manufacture the modules in the construction site. The
modules then will be used to build up the building. The integrated design of a
module will probably include some or all of the HVAC and sanitary components
and we can imagine that they will be produced during the additive manufacturing
phase.
There are
some signs of awareness on the topic, but not being discussed widely. Additive
manufacturing is being used in the prototyping phase of HVAC components and
equipment, especially by the fan manufacturers. Some researchers has focused on
the heat exchanger technology. A team from University of Maryland used direct
metal printing (DMP) to manufacture the miniaturized heat exchanger as a
single, continuous piece using titanium [4]. Another example is the design,
fabrication, and test of a plastic heat exchanger [5]. However, there is not
any information about these research and development studies that they have
resulted to mass production by additive manufacturing.
Two
important studies on the possible status of additive manufacturing and
integrated design are reported by Tibaut et al. [6] and Joplin [7]. Tibaut et
al. [6] introduced the concept “Digital Fabricated Buildings” and reports that
additive manufacturing has potential to be “the next big step forward” for the
AECO (Architecture, Engineering, Construction and Owner-operated) industry.
Although application of large-scale additive manufacturing systems in this
industry is in early research phase, it is expected that are further
parameterization of the interoperability demand function, BIM maturity, automation
of workflow models, and new approaches for engineering of embedded building
elements will be the important research and application topics of the near
future [6]. New approaches for engineering includes freeform constructions
inspired by the nature for the building construction elements and HVAC,
sanitary, electrical etc. components. Joplin [7] reported the Innovations That
Will Change HVAC Forever including 3-D Printed Air Conditioners as an expected
consumer product of the future.
We predict
that additive manufacturing will be the primary method for the production of;
firstly components such as heat exchangers (3D-CM), followed by the Equipment
Manufacturing (3D-EM), and finally the technology will be adopted to the
integrated design and 3D building construction (3D-BC).
A task force
has been established to work on a project about implementation of additive
manufacturing technology to HRV (Heat Recovery Ventilation) systems including
all three phases of the progress as 3D component manufacturing, equipment
manufacturing, and building construction in İzmir (Turkey). The first step
is component manufacturing and we have started with the heat exchangers. Cellulose,
pet, or aluminum heat exchangers are mostly used in HRV systems. A wide range
of materials are available for additive manufacturing but ABS (Acrylonitrile
Butadiene Styrene) was used to produce the air-to-air cross-flow plate heat
exchanger material. As this is a conceptual study the material is not the
primary matter of interest, instead producibility is the main concern.
The main
parameter that effect the producibility is geometry. A new approach to
geometric design needed. Different than the conventional manufacturing methods,
adding material in a discrete manner totally changes the dimensioning and
tolerancing strategies during design. The critical geometric parameters are
layer thickness, single wall thickness, and nozzle diameter while using the
additive manufacturing method. There are a wide range of 3D printers in the
market and the technology is in a very fast progress. Therefore, supply and
demand balance will be ruled by the demand side in the near future.
In our
case, heat exchangers always have gaps. Another question is question is how can
we build gaps by adding material? Support materials or supporting structures
are used during manufacturing. After the manufacturing process, cleaning starts
either mechanically or chemically. However in tiny gaps mechanical cleaning is
very hard. More time, material and money is used when supports are used. A more
logical solution is constructing a self-supported geometry that can be manufactured
without using any supports. Topology optimization is the keyword while
determining the most efficient way of manufacturing process, and also having an
optimized performance of heat exchanger by means of heat transfer and pressure
drop. There many other problems waiting ahead. But the opportunities of the
additive manufacturing by means of free form or non-linear geometric designs
will certainly produce more efficient components. Same examples of the heat
exchangers produced by additive manufacturing are given in Figure 2.
Figure 2. Same
examples of the heat exchangers produced by additive manufacturing
The next
level is equipment manufacturing. An ordinary commercial HRV unit which is
manufactured and designed for conventional production. Many processes exist
during manufacturing of this unit. A hybrid approach is to produce the casing
by additive manufacturing, which can be manufactured as a single continuous
piece, and other components (heat exchanger, fans, filters, and electronic
equipment) are assembled afterwards (Figure 3-a). A more additiveapproach would be to produce the body and the
heat exchanger as a single continuous piece and assemble the other components
afterwards (Figure 3-b). When you are free about the
production method and supply procedures, you can free your mind and focus on
the main problem, engineering. The second design (Figure 3-b) has a heat exchanger volume of
almost twice the first one (Figure 3-a), when the outer dimensions are
kept constant. Engineering and integrated design will be more important than
ever when the method is fully available for the industry. We are on our way.
Figure 3. Samples of HRV
units produced by additive manufacturing. |
Figure 4.
Integrated design of an apartment for additive manufacturing.
The last
level of our future perspective is the building construction. By conventional
methods we can calculate the loads and select a system from any manufacturer. Latest
technology enables us to embed (immerse) the ducts into the building, while we
are constructing the building. But when we go a step forward, together with the
ducts embedded into the building elements, we will be able to embed units also
into the walls or facade of the building. Figure 4 shows the integrated design of an apartment
for which we have calculated the loads, prepared a CAM model for additive
manufacturing and the HRV unit embedded into a wall together with the ducts. It
is ready for construction.
1. Additive manufacturing will be an alternative tool for manufacturing firstly the HVAC
components, then the units (HRVU, AHU, etc.) in the near future.
2. The days that additive manufacturing will be
used for production
of all of the components (walls, roof, ducts) of a building on site in a holistic approach is not so far.
3. Additive manufacturing will change the World
from Cartesian design to non-Cartesian (freeform, nonlinear). This will enable more compact unit designs
with higher performance while keeping the capacity the same.
4. Additive manufacturing will enforce designers of different disciplines to cooperate for integrated design.
5. Integrated building design for additive
manufacturing will arise a new sector that will be developing software for 3D printed components designed for both Cartesian and
non-Cartesian geometries.
[1] Tomlinson, Charles (1850-01-01). A
rudimentary treatise on warming and ventilation: being a concise exposition of
the general principles of the art of warming and ventilating domestic and
public buildings, mines, lighthouses, ships, etc. J. Weale. p. 53.
[2] http://stephenjressler.com/portfolio/hypocaust/.
[3] Khoshnevis, Behrokh. Houses of the Future:
Construction by Contour Crafting Building Houses for Everyone. University of
Southern California, 2004.
[3] https://all3dp.com/1/3d-printed-house-homes-buildings-3d-printing-construction/,
24.04.2017.
[4] http://www.ceee.umd.edu/news/news_story.php?id=9709,
24.04.2017.
[5] http://eng.umd.edu/release/new-3dprinted-plastic-heat-exchanger-shows-complex-geometries-are-possible-from-additive-manufacturing,
24.04.2017.
[6] Tibaut, Andrej, Nenad Čuš Babič,
and Matjaž Nekrep Perc. "Integrated Design in Case of Digital Fabricated
Buildings." Energy Procedia 96 (2016): 212–217.
[7] http://www.joplins.net/articles/11-innovations-that-will-change-hvac-forever
24.04.2017.
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