Eco-Design of a Small Size Industrial Fan for Ceramic Tile Cooling

G3 - Fan Efficiency

Energy consumption and savings in domestic and industrial applications of fans have recently gained attention in Europe. In a recent European Directive (2009/125/EC), eco-design demands for products that can have a critical environmental impact and, at the same time, can present significant potential for improvement through innovative design, have been set.
Fan design must fulfil a number of requirements in order to ensure: (i) minimum energy consumption (also of installed auxiliary devices), (ii) proper fluid dynamic performances (air flow rate, pressure rise and efficiency) and (iii) minimun manufacturing and maintenance costs.
In most cases installation and process requirements (such as space constrains, electrical power limits, national and international directives in the field of health and safety) do not match with consolidated fluid dynamic design approaches. In this context, Computational Fluid Dynamics (CFD) is the key tool which can complement traditional one-dimensional and bi-dimensional design approaches.
In this paper, mono-dimensional design and three-dimensional optimization through CFD numerical simulations of an industrial fan are carried out. The fan under consideration provides the airflow used for controlling the thermal gradient of ceramic tiles before entering the digital printer stage. For this reason, the air velocity field at the blowing device outlet is also considered as a design constraint during the three-dimensional optimization.
In order to establish the specific application requirements, a simplified numerical model of the tile heat exchange is developed and used to fix the air velocity threshold value above which tile cooling is sufficiently efficient.
During the design process, the existing Sirocco runner, often used for heating and cooling applications for its capability to deliver more air volume than other centrifugal fans of the same size and rotational speed, is substituted by a backward-curved centrifugal fan in order to meet increased process and eco-design requirements.
Experimental campaing on a backward-curved fan prototype with optimized air blowing device demonstrates that fan performances (air volume and efficiency) meet the eco-design demands and the air velocity field at the blowing device outlet is suitable to obtain the expected heat exchange. The new design can also reduce acoustic emissions up to 3 dB(A).
The coupling of one-dimensional design and three-dimensional CFD simulations allow the fullfilment of different demands such as energy saving, process requirements and health legislation.