Modelling anti-icing of railway overhead catenary wires by resistive heatingShow others and affiliations
2019 (English)In: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 143, article id 118505Article in journal (Refereed) Published
Abstract [en]
Aggregation of ice on electrical cables and apparatus can cause severe equipment malfunction and is thus considered as a serious problem, especially in arctic climate zones. In particular, cable damage caused by ice accumulation on railway catenary wires is in wintertime a common origin for delayed trains in the northern parts of Europe. This study examines how resistive heating can be used for preventing formation of ice on metallic, non-insulated electrical cables. The heat equation and the Navier Stokes equations were solved simultaneously with FEM in 3D in order to predict the cable temperature as function of external temperature, applied voltage, wind speed, wind direction, and heating time. An analytical expression for the heat transfer coefficient was derived from the FEM simulations and it was concluded that the influence of wind direction can typically be neglected. Experimental validation measurements were performed on Kanthal cables in a climate chamber, giving temperature increase results in good agreement with the simulation predictions. The resistive heating efficiency, i.e. the ratio between applied electrical energy and resulting thermal energy, was found to be approximately 68% in this particular study.
Place, publisher, year, edition, pages
Elsevier Ltd , 2019. Vol. 143, article id 118505
Keywords [en]
FEM, Ice-prevention, Kanthal, Railway overhead lines, Resistive heating
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-39790DOI: 10.1016/j.ijheatmasstransfer.2019.118505Scopus ID: 2-s2.0-85070233997OAI: oai:DiVA.org:ri-39790DiVA, id: diva2:1343738
Note
Funding text 1: The SP Technical Institute of Sweden is gratefully acknowledged for financial support as part of the Eurostars-funded project IceControl. Appendix A Zsolt et al [40] developed a model for predicting the current I needed to prevent ice accretion of electrical overhead lines by resistive heating. In this case the factors in the heat-balance are q j (resistive joule heating), q c (heat loss due to convection), q f (heat flow rate due to stagnation and friction in the boundary layer), q e (heat loss due to evaporation) and q w (heat loss due to impinging droplets [63–66] : (A1) q j = q c - q f + q e + q w (A2) q j = R I 2 L (A3) q c = h ( T - T ref ) 2 π r ∼ L (A4) q f = 0.79 · 2 π r ∼ L · h v 2 / ( 2 c p ) (A5) q e = 0.622 h l e · π r ∼ L · ( p s - p a ) / c p p (A6) q w = κ 1 κ 2 W v E · 2 r L c w ( T - T 0 ) The parameters used in A1-A6 are: resistance (per meter) R , current I , cable length L , heat transfer coefficient h , cable surface temperature T , atmosphere temperature T 0 , effective cable radius r ∼ , wind speed v , specific heat c p , latent heat of evaporation l e , saturation vapour pressure at cable surface p s and in atmosphere p a , atmospheric pressure p , correction factors κ 1 and κ 2 , liquid water content W , collection efficiency E , cable radius r, and specific heat of liquid water c w . When Eqs. A1-A7 are combined, they can be used to calculate the current needed to prevent ice accretion: (A7) I = 2 π r ∼ R h ( T - T 0 ) - 0.79 h v 2 2 c p + 0.622 h l e ( p s - p a ) 2 c p p + r κ 1 κ 2 E W v c w ( T - T 0 ) r ∼ π 0.5
2019-08-192019-08-192023-05-25Bibliographically approved