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ASSESSING THE THERMAL PROPERTIES OF 3D PRINTED WALLS
paper recently published in the journal Energies has
A evaluated the thermal properties of three-dimensional ( 3D ) -printed walls .
Additive manufacturing or 3D printing , characterised by a low-cost and fast building process , is increasingly gaining prominence in the construction industry . Additive manufacturing has become a common technique to create entire devices or parts , as it allows for rapid prototyping and on-demand manufacturing .
The integration of 3D printed concrete ( 3DPC ) technology with a modular building system can provide sustainable solutions to current construction challenges . 3DPC technology can increase thermal comfort and decrease energy consumption in a room when integrated and hybridised with other energyefficient technologies .
Topology optimisation can be used to adjust the 3DPC thermal resistance characteristics . For instance , cavities can be introduced in areas requiring low thermal conductivity to improve the insulation properties . However , assessing the energy efficiency and topology optimisation of the enclosed structures is necessary using numerical modeling .
Mebner1 | Pixabay
In this study , researchers investigated the energy efficiency and suitability of 3D-printed enclosing structures and determined the optimal configuration to obtain enclosing structures with the most suitable thermal characteristics .
THE STUDY In this study , researchers investigated the energy efficiency and suitability of 3D-printed enclosing structures and determined the optimal configuration to obtain enclosing structures with the most suitable thermal characteristics . The thermal resistance coefficient of 3D printed structures was evaluated . A mathematical model was created to describe the mass and heat transfer process , and the proposed model was validated by comparing the model with experimental results .
Mathematical modeling can determine the heat transfer resistance as it can accurately estimate integral characteristics , such as average surface heat flux , compared to an experiment where these values are determined only at monitoring points .
Multiple enclosed structures were selected for the numerical study . The internal structure of cavities of these structures differed from each other . However , all structures were similar in terms of form factor . The linear dimensions were the same for all structures , excluding the structure depth .
The selection of the 3D-printed enclosed structure / additive wall panel for the physical experiment was based on the preliminary numerical studies . The test equipment used in the physical experiment set up to investigate the thermal properties of the additive wall panel included climatic chamber number one , climatic chamber number two , and a temperature and flux density meter .
Nemova , D et al .
In the climatic chamber number one , the supported temperature range was from −70 ° C to + 100 ° C , while in the climatic chamber number two , the temperature range was from −70 ° C to + 180 ° C .
The size of the 3D-printed wall panel was 390 mm × 680 mm × 310 mm , and the thickness of the structure was 35 mm . A dry mix was utilised for additive manufacturing of the panel . The maximum aggregate fraction size in the dry mix was 0.63 mm . Overall , 1800 kg of the dry mix was used to prepare the one m 3 structure , and 0.13 – 0.16 L of water was required to mix one kg of dry mix .
The mixture was used after hardening . The compressive strength and bending tensile strength of the hardened mixture after 24 hrs measured 18 MPa and 4 MPa , respectively , and after 28 days the readings were 40 MPa and 8 MPa , respectively . The elasticity modulus was 26 GPa . The prepared panel can be applied in all climatic zones .
The types of enclosing structures evaluated in the study .
www . refrigerationandaircon . co . za RACA Journal I November 2022 9