A small simulation study of moisture content variations in furniture in different tropical climates

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1 A small simulatin study f misture ntent variatins in furniture in different trpial limates Wadsö, Lars 1994 Link t publiatin Citatin fr published versin (APA): Wadsö, L. (1994). A small simulatin study f misture ntent variatins in furniture in different trpial limates. (Reprt TVBM (Intern 7-rapprt); Vl. 781). Divisin f Building Materials, LTH, Lund University. General rights Cpyright and mral rights fr the publiatins made aessible in the publi prtal are retained by the authrs and/r ther pyright wners and it is a nditin f aessing publiatins that users regnise and abide by the legal requirements assiated with these rights. Users may dwnlad and print ne py f any publiatin frm the publi prtal fr the purpse f private study r researh. Yu may nt further distribute the material r use it fr any prfit-making ativity r mmerial gain Yu may freely distribute the URL identifying the publiatin in the publi prtal Take dwn pliy If yu believe that this dument breahes pyright please ntat us prviding details, and we will remve aess t the wrk immediately and investigate yur laim. L UNDUNI VRS I TY PO Bx L und

2 LUNDS TKNISKA HOGSKOLA Byggnadsmaterial UNIVRSITY OF LUND LUND INSTITUT OF TCHNOLOGY Divisin f Building Materials A small simulatin study f misture ntent variatins in furniture in different trpial limates Lars Wadsö Rapprt TVBM-781 Lund, augusti 1994

t thse fr wden parts with square r retangular rss setins with the smallest dimensins equal t the dimensins given abve. Material data The srptín istherm used was taken frm Avramidís (1989).

3 t thse fr wden parts with square r retangular rss setins with the smallest dimensins equal t the dimensins given abve. Material data The srptín istherm used was taken frm Avramidís (1989). lt is based n the well knwn USDA istherm, whíh is mean f an absrptin and a desrptin istherm. The istherm was taken at 2C frm the equatin given by Avramides fr an stherm arding t an equatin frm Zuritz et al. Figure 2 shws the istherm. The diffusivity used was taken frm Siau (1984). lt is a theretially alulated sftwd diffusivity whih is in the same range as reently measured diffusivities. lt was alulated at 2C. Figure 3 shws its variatins with misture ntent (the diffusivity has misture nentratin, kg/m3, in wd as ptential). The ply-urethane ating has a mass transfer resistane f 1 s/m (Nevander and lmarssn 1981, vapr ntent f air as ptential). A similar value was given by a majr atings manufaturer fr ne layer f their ply-urethane ating. Results Figures 4-7 gives the results f the simulatins fr the fur fumiture mpnents. Disussin It shuld be nted that the alulated amplitudes in misture ntent are prbably t large as there was n hysteresis in the used istherm. The hysteresis (and pssibly the anmalus srptin disussed by Wadsö 1994 and thers) will derease the misture ntent variatins. Daily RH variatins wuld ertaínly influene the misture ntent f furniture part A (the thin veneer). Figure 4 des, hwever, give a values lse t the daily mean misture ntent. A number f (mre r less trivial) nlusins may be drawn frm the results: - Thin veneers fllw the variatins in relatíve humidity lsefy. - Thiker wd piees have dampened mean misture ntent variatins. - Cated wd has dampened mean misture ntent variatins. The dampening resufting frm a ating is dependent n the vapr resistane f the ating. ln the present ase the value used was fr a ply-urethane ating whih has amng the highest vapr resistanes f wd atings. Still the dampening was nt mre than t abunt 6% f the unated wd. A ating des derease the misture ntent variatins, but an never eliminate the raise in misture ntent in a humid limate. Shrinkage/swellíng is apprximately prprtinalt the misture ntent shwn in Figs. 4-7 Referenes Arfuidssn, J. and Claessn, J. (1989), A PC-based methd t alulate misture transprt, Pr. Heat and Mass Transfer in Building Material and Struture, 4-8 September 1989, Dubrvnik, Yugslvía, d. Chadwik. Avramidis, S. (1989), valuatin f three-variable' mdels fr the preditin f equilibrium misture ntent in wd, Wd Si. Tehnl Nevander, L.. anl lmarssn, B. 1981, Fukthandbken, Svensk Byggtjänst, Stkhlm, Sweden

4 Siau, J.F. (1984), Transprt presses in wd, Springer-Verlag.t!adsö. L. (1994), Unsteady-state water vapr adsrptin in wd: an experimental study, Wd Fiber Si., 26(1) 36-

5 3 2 ñ 2 ( ) () (l) L = relative humidity, % Figure 1. Srptin istherrn frm Avramidis (1989).

6 -1 x U' (\ 3 = att J =u Pigure 2. diretin Diffusivity ( Siau L984). misture ntent, 7 f sftwd in the transversal 2 2 3

$1 9.\ 8 3 7 { =p = -.$

7 1 9.\ { =p = -.2 ((t ( ) / time, mnths Figure 3. The simulated limates (nte that their mean value at t=). they all start with

8 2 veneer (fig2) lhs 2 s = -art 1 1 \ \ time, mnths Figure 4. Simulatin fr the 1 mm veneer (A).

9 2 1mm*2 (fig3) lhs 2 { =.ut 1 \ \ I I 3 a time, mnths Figure. Simulatins fr the ZO mm sample (B).

10 2 mm'2 (fi94) lhs 2 1 s () (l) f _ut time, mnths Figure 6. Simulatins fr the 1 mm sample (C).

11 2 1mm'2+PU (fig) lhs 2 I àe Ê (t L J time, mnths Figure 7. Sinulatins fr the ated 2 mm sample ).

Content 1. Introduction 2. The Field s Configuration 3. The Lorentz Force 4. The Ampere Force 5. Discussion References

Content 1. Introduction 2. The Field s Configuration 3. The Lorentz Force 4. The Ampere Force 5. Discussion References Khmelnik S. I. Lrentz Fre, Ampere Fre and Mmentum Cnservatin Law Quantitative. Analysis and Crllaries. Abstrat It is knwn that Lrentz Fre and Ampere fre ntradits the Third Newtn Law, but it des nt ntradit