Heat Transfer and Energy Efficiency in Infrared Paper Dryers

Magnus Pettersson

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Infrared (IR) dryers are widely used in the paper industry, mainly in the production of coated paper grades. The thesis deals with various aspects of heat transfer and energy use in infrared heaters and dryers as employed in the paper industry. Both gas-fired and electric IR dryers are considered and compared. The thesis also provides an introduction to infrared heaters and infrared drying, including a review of recent literature in the field.

The transport of thermal radiation inside a paper sheet was investigated and different IR dryers were compared in terms of their ability to transfer energy to the internal parts of a paper sheet. Although there were evident differences in the absorption of radiation between gas-fired and electric IR dryers, the distinction was found to not be as important as has generally been believed. The main differences appeared to be due to the choice of a one- or a two-sided dryer solution, rather than the spectral distributions emitted by the dryers.

A method for evaluating the radiation efficiency of IR heaters was proposed. An electric IR heater was evaluated in the laboratory. The radiation efficiency of the heater was shown to be strongly dependent on the power level. The maximum efficiency, found at high power level, was close to 60 %. A procedure for evaluation of the total energy transfer efficiency of an infrared paper dryer was proposed and used in the evaluation of an electric IR dryer operating in an industrial coating machine. The efficiency of the dryer was roughly 40 %.

A model for an electric IR heater was developed. The model includes non-grey radiative heat transfer between the different parts of the heater, as well as conduction in reflector material and convective cooling of the surfaces. Using IR module voltage as the only input, model predictions of temperatures and heat flux were found to agree well with experimental data both at steady state and under transient conditions. The model was also extended to include features typical of an industrial IR dryer and was used to predict trends in IR dryer efficiency in relation to changes in power level and in paper grade.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Department of Chemical Engineering
Supervisors/Advisors
  • [unknown], [unknown], Supervisor, External person
Award date1999 Dec 10
Publisher
ISBN (Print)91-628-3733-8
Publication statusPublished - 1999

Bibliographical note

Defence details

Date: 1999-12-10
Time: 10:15
Place: Lecture hall C, Chemical Center, Lund

External reviewer(s)

Name: Seyed-Yagoobi, Jamal
Title: Professor
Affiliation: Texas A&M University, College Station, Texas, USA

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Article: I. Pettersson, Magnus; Stenström, Stig; Absorption of Infrared Radiation and the Radiation Transfer Mechanism in Paper. Part I. Theoretical Model; Journal of Pulp and Paper Science, Vol. 24, No. 11, pp. 349-355, November 1998.

Article: II. Pettersson, Magnus; Stenström, Stig; Absorption of Infrared Radiation and the Radiation Transfer Mechanism in Paper. Part II. Application to Infrared Dryers; Journal of Pulp and Paper Science, Vol. 24, No. 11, pp. 356-363, November 1998.

Article: III. Pettersson, Magnus; Stenström, Stig; Experimental Evaluation of Electric Infrared Dryers; TAPPI Journal (Accepted).

Article: IV. Pettersson, Magnus; Stenström, Stig; Evaluation of gas-fired and electrically heated industrial infrared paper dryers; International Gas Research Conference 1998 (IGRC 98), Vol. 5, pp. 210-221, San Diego, November 8-11, 1998.

Article: V. Pettersson, Magnus; Stenström, Stig; Modelling of an Electric IR Heater at Transient and Steady State Conditions. Part I: Model and Validation; International Journal of Heat and Mass Transfer (in press).

Article: VI. Pettersson, Magnus; Stenström, Stig; Modelling of an Electric IR Heater at Transient and Steady State Conditions. Part II: Modelling a paper dryer; International Journal of Heat and Mass Transfer (in press).

Subject classification (UKÄ)

  • Chemical Engineering

Keywords

  • experimental
  • modelling
  • electricity
  • gas
  • efficiency
  • energy
  • drying
  • dryer
  • heat transfer
  • radiation
  • paper
  • infrared
  • IR
  • coating
  • Chemical technology and engineering
  • Kemiteknik och kemisk teknologi

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