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Abstract
Considerable effort has been expended in the past two decades in constructing mathematical models of cellular foams used in insulation for buildings and applicances. This work is important because of realistic model with good predictive capabilities would facilitate the improvement if this type of insulation which is commonly closed cell polyurethane (PUR) or polyisocyanurate (PIR) blown with CFC-11. Foam technology is quite complex because it spans many diverse disciplines from organic chemistry to reaction kinetics, heat and mass transport, strength of materials, and surface chemistry on the more theoretical side to large scale conveyor machine laimination, mix formulation and statistical quality control on the practical end. In large part, for this reason there is much art involved in successful foam manufacture. This has made for difficulties in optimization because so much information is proprietary that developments in the broad sense are hampered by the lack of a good data base. Mathematical models which incorporate the key features of real systems thus assume a special status in being able to accelerate development of improved insulation with savings in time and money. For this reason, it seems worthwhile to review some of the underpinnings of current models in order to stimulate work in areas where useful information is lacking and where improvements are needed. In this paper several aspects of key features of current foam models are examined and the framework for a new type of model is developed in which open cells are taken into account. Other aspects such as radiation heat transfer, and blowing agent condensation are also worthy of further study, but they are not discussed.
Considerable effort has been expended in the past two decades in constructing mathematical models of cellular foams used in insulation for buildings and applicances. This work is important because of realistic model with good predictive capabilities would facilitate the improvement if this type of insulation which is commonly closed cell polyurethane (PUR) or polyisocyanurate (PIR) blown with CFC-11. Foam technology is quite complex because it spans many diverse disciplines from organic chemistry to reaction kinetics, heat and mass transport, strength of materials, and surface chemistry on the more theoretical side to large scale conveyor machine laimination, mix formulation and statistical quality control on the practical end. In large part, for this reason there is much art involved in successful foam manufacture. This has made for difficulties in optimization because so much information is proprietary that developments in the broad sense are hampered by the lack of a good data base. Mathematical models which incorporate the key features of real systems thus assume a special status in being able to accelerate development of improved insulation with savings in time and money. For this reason, it seems worthwhile to review some of the underpinnings of current models in order to stimulate work in areas where useful information is lacking and where improvements are needed. In this paper several aspects of key features of current foam models are examined and the framework for a new type of model is developed in which open cells are taken into account. Other aspects such as radiation heat transfer, and blowing agent condensation are also worthy of further study, but they are not discussed.
Date
9/1989
9/1989
Author(s)
Dale Bandreth
Dale Bandreth
Page(s)
20
20
Keyword(s)
cellular foam; polyisocyanurate; CFC-11; trichlorofluoromethane; ozone depletion; HCFC
cellular foam; polyisocyanurate; CFC-11; trichlorofluoromethane; ozone depletion; HCFC