A theoretical model describing the heat and moisture transfer which takes place when a mattress of particles is hol pressed is prescnted.This simulates conduction, the phase change of water from the adsorbed state to the vapour state, and convection.The model predicts the flow of vapour and the conduction of heat between the press platens and the central layer of the mattress, and also between the centre of the mattress and the edge of the press. 1t can thus be termed thrce dimensional.The theoretical assumptions made in the model are discussed, and typical predictions presentcd.Brought to you by | University of Queensland -UQ Library Authenticated Download Date | 6/14/15 2:43 PM Brought to you by |

KeywordsWood-bascd compositcs Particlcboard Hot prcssing Modclling Tcmpcrature Vapour prcssurc Hcat and moisturc transfcr Sitka sprucc Ptcea sitchensis SummaryUsing a thcorctical modcl, thc Variation of tcmpcraturc and vapour prcssurc within a particlcboard mattrcss during thc hot prcssing Operation is prcdictcd. Changc in thcsc variables with timc at a givcn Position in thc mattrcss, or with position in cithcr a vcrtical or a horizontal plane at a givcn timc, can rcadily bc studicd.Thc cffcct of a numbcr of proccssing variables on tcmpcraturc and vapour prcssurc Variation is analyscd, with the prcdictions of thc modcl bcing comparcd with cxpcrimcntal data. Thc prcdictcd data agrce well in trcnd, if not in absolute magnitudc, with thosc obscrvcd cxpcrimcntalty.

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