The laboratory received 4 samples, composed of a substrate board of 4 mm, finished with Hot Pipe Coating. Characteristics:

Transcription

1 FACULTEIT INGENIEURSWETENSCHAPPEN DEPARTEMENT BURGERLIJKE BOUWKUNDE LABORATORIUM BOUWFYSICA KASTEELPARK ARENBERG 40 B-3001 LEUVEN RAPPORT KATHOLIEKE UNIVERSITEIT LEUVEN Superior products NV Kmpweg, Wuustwezel Hot Pipe Coting Therml conductivity 1. Introduction Report 006/0 (1) On November 8, 006, the Superior Products NV compny demnded the Lbortory of Building Physics t the K.U.Leuven to mesure the therml conductivity of Hot Pipe Coting. This report describes the mesuring method, gives the results of the mesurements nd contins short discussion on ccurcy nd vlues to use.. Therml conductivity of Hot Pipe Coting.1 Smples The lbortory received 4 smples, composed of substrte bord of 4 mm, finished with Hot Pipe Coting. Chrcteristics:. Mesurements..1 Method Smple Thickness M Weight G Therml resistnce of the 4 smples ws mesured with the het flow meter pprtus for smples 30x30 cm, s described in the stndrd ISO 830 (figure 1). The pprtus consists of centrl hot plte with cold plte bove nd below. Tht wy, two smples cn be tested t the sme time. Round het flow meters with dimeter of 10 cm re positioned centrlly t the underside of the top plte, t both sides of the centrl plte nd t the upside of the lower TEL. (016) FAX (016)

2 plte. These het flow meters re embedded in neoprene lyer with the sme thickness s the meters nd s lrge s the re of the pltes. In the centre of ech plte side, extremely thin Cu/Co thermocouples re glued ginst the het flow meters. The smples re then mounted between the top plte nd the centrl plte nd between the lower plte nd the centrl plte. The whole is finlly pcked in thermlly isolting box s to crete close to dibtic conditions round the set-up. Before the mesurements strted, the het flow meters were reclibrted using the reference smples of the EU s BCR. Figure 1 The experimentl set-up. The centrl Figuur plte 1: Opbouw is coloured vn de in opstelling. red, the top De nd centrle bottom plt plte is in rood blue. gekleurd, The thick de onderste en bovenste plt bluw. blck line round the set-up coincides De zwrte lijn rondom de opstelling with the borders of the insulted box, wijst op isoltie rondom de which should crete ner dibtic cm opstelling. Die is nodig om het border between the set-up nd the geheel ±dibtisch te mken. De environment. The thinner blck lines zwrte lijnen tegen de drie plten ginst the pltes represent the stellen de neopreenlgen voor, neoprene lyers with embedded het wrin de wrmtestroommeters flow ingebed meters zitten. Temperture difference between the thermosttic bth tht keeps the top nd lower cold plte on temperture nd the thermosttic bth tht keeps the centrl wrm plte on temperture is set t 10. As soon s the tempertures nd the het fluxes t both surfces of the smples turn constnt, ll dt re logged t time intervl of 10 nd stored on hrd disk. All further clcultions re done in Excel: trnsforming the 10 vlues in verges spnning three hours nd clculting therml resistnce with the following eqution: with: C 1, C E 1, E R = (m².k/w) [1] C 1E1 + C E Clibrtion constnts of the het flow meters in W/(m².mV)) Mesured electricl voltge difference over the het flow meters in mv Temperture difference over the smples in K (mesured with the Cu/Co thermocouples)

3 .. Mesured results Smple Thickness m Vol. moisture rtio %m 3 /m (1) The lst number in superscript is unsure Men temperture Temp. Difference Therml resistnce (1) m².k/w Mesuring ccurcy The mximum uncertinty on the mesured dt is given by: R R q + q qrn + with q het flux in W/m². The term qrn [] represents systemtic filure, the consequence of kind of zero thickness therml resistnce between the pltes nd the smples in between (in m².k/w). In the cse being, its vlue does not pss m².k/w. As most probble uncertinty, one hs: R R ± q q + ± qrn [3] Results: 3

4 Smple..4 Discussion q q qrn Mximum uncertinty Most probble uncertinty % % % % % Therml permence versus men temperture The mesured dt llow constructing the reltionship between therml permence of the smples nd the men temperture in the smples. A lest squre nlysis gives: In generl 1 P = = + b R with P therml permence in W/(m².K) (is the inverse of therml resistnce) nd verge temperture in Smples 1 nd Smples 3 nd 4 = b σ = σ r² = vlues b = = F = 366 See lso the figures nd = 3.69 b σ = σ r² = vlues b = = F = 1.3 [4][5] Therml permence (W/(m².K)) Men temperture () Figure Smples 1 nd, reltionship between therml permence nd men temperture in the mteril 4

5 4.000 Therml permence (W/(m².K)) Men temperture () Figure 3 Smples 3 nd 4, reltionship between therml permence nd men temperture in the mteril..4. Therml conductivity of Hot Pipe Coting The smples 1, 3 en 4 re composed of 4 mm thick substrte bord finished with Hot Pipe Coting. With other words, the smples 1 nd contin mm, respectively mm of cermic pste, while the smples 3 nd 4 contin mm, respectively mm of cermic pste. If we cll the therml resistnce of the substrte bord R o, then t ech men temperture, we my write: d hpc R = + R λ hpc o Tht gives four equtions per temperture step with two unknown: λ hpc en R o. These equtions hve been solved sttisticlly, resulting in therml resistnce R o for the substrte bord of m².k/w, while the therml conductivity of the cermic pste becme: In formul: λ = = r² = vlues b =.5 10 F = 6. Men temperture Therml conductivity W/(m.K)

6 Also see figure 4. Uncertinty: mximum of ±6.3% nd most probble vlue of ±3.5%. Therml conductivity t men temperture of 10: λ=0.061 ±0.00 i.e. rther high vlue. The reson is the quite high density of Hot Pipe Coting: not less thn 99 ±3.3 kg/m Therml conductivity (W/(m.K)) Men temperture () Figure 4 Reltion between the therml conductivity of Hot Pipe Coting nd its verge temperture..4.3 Therml conductivity t different men tempertures These re given in the following tble: Men temperture Therml conductivity W/(m.K) As ll insulting mterils, Hot Pipe Coting performs the best t low tempertures. Above men temperture of 350, its therml conductivity psses 0.1 W/(m.K). The effect on the surfce temperture nd the het loss of 1 meter run steel pipe thus depends on the temperture of the fluid in the pipe, de insultion thickness pplied, the dimeter of the pipe 6

7 nd the fct of the pipe hngs inside or outside. Only to illustrte the effect of Hot Pipe Coting, we clculted the reduction in het loss per meter run for steel pipe with n exterior dimeter of 10 cm, hung in n environment with n effective temperture of 0. The pipe trnsports 350 hot fluid nd is insulted with 1 cm thick lyer of Hot Pipe Coting. Without coting, the het loss touches 3409 W/m. With Hot Pipe Coting it diminishes to 776 W/m, i.e. decrese with 77.3%. The verge therml conductivity in the coting then reches W/(m.K). Leuven, 4/7/007 H. Hens Professor 7