Heat Recovery for a Textile Stenter: CFD Analysis of Air Curtain Benefits

Lorenzo Ciappi, Daniele Fiaschi, Giampaolo Manfrida, Simone Salvadori, Jacek Smolka and Lorenzo Talluri
Additional contact information
Lorenzo Ciappi: Department of Industrial Engineering, University of Florence, I50135 Florence, Italy
Daniele Fiaschi: Department of Industrial Engineering, University of Florence, I50135 Florence, Italy
Giampaolo Manfrida: Department of Industrial Engineering, University of Florence, I50135 Florence, Italy
Simone Salvadori: Department of Industrial Engineering, University of Florence, I50135 Florence, Italy
Jacek Smolka: Institute of Thermal Technology, Silesian University of Technology, 44100 Gliwice, Poland
Lorenzo Talluri: Department of Industrial Engineering, University of Florence, I50135 Florence, Italy

Energies, 2019, vol. 12, issue 3, 1-22

Abstract: Modern textile stenters are designed to reduce the inefficiency of the process and to recover the flow stream, which still contains a relatively high energetic value. In recent years, research has focused on the recovery of the energy content of the low-temperature exhaust flow; nonetheless, another important aspect that may increase the efficiency of the process is the reduction of the ambient air suction. In the present research, an innovative way to improve both machine insulation and energy savings, by using preheated air, was numerically evaluated. The proposed solution utilizes an air stream transverse to the fabric (generally called air curtain), either preheated or not, to create soft gates both at the inlet and at the outlet section of the drying machine. Several valuable advantages can be listed when using this solution: reduction of the dispersion of heat and humid polluted air to the work environment, limitation of air ingestion from outside, and effective heat recovery coupled to a uniform temperature profile around the textile fabric. To analyze the insulation capability of the air curtains in terms of mass and energy transfer, a two-dimensional CFD model of the machine was realized. A test matrix including three possible fabric speeds (20, 40 and 60 m/min), three tilt angles (−15°, 0° and 15°), four mass flow rates (0% with no air curtains and 3%, 5% and 7% of the total flow rate through the machine, where the 5% case is equivalent to the flow rate ingested from the ambient) and two temperatures (15 °C and 70 °C) of the plane jets exiting from the air curtains was considered, thus covering a wide range of possible practical applications. The obtained results demonstrate that warm air curtains at both the inlet and outlet are very effective in a fabric speed range up to 40 m/min; at higher fabric speed, entrainment of warm gases from inside the machine at the fabric outlet becomes relevant, and the adoption of a cold air curtain (capable of better insulation) can be recommended in this position.

Keywords: air curtain; textile dryer; stenter; energy saving; computational fluid dynamics (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
https://www.mdpi.com/1996-1073/12/3/482/pdf (application/pdf)
https://www.mdpi.com/1996-1073/12/3/482/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:12:y:2019:i:3:p:482-:d:203132

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().