硬质聚氨酯泡沫低温比热容的试验

Experiment of specific heat capacity of rigid polyurethane foam at low temperature

为了研究过渡型和环境友好型聚氨酯泡沫的低温比热容对低温绝热机构设计的影响,建立了一套绝热量热装置,通过各种措施最大限度地降低了漏热损失,对传统的CFC-11泡沫、过渡型HCFC-141b泡沫及环境友好型HFC-245fa泡沫,在温度为60 K至常温范围内的比热容进行了试验.研究结果表明:不同泡沫的比热容随着温度的上升而上升;同种泡沫,密度增大时,泡沫比热容也随之增加,但在低温区密度的影响程度变小;相同密度下,3种泡沫的比热容由大到小的顺序为HFC-245fa,HCFC-141b,CFC-11;在低温区发泡剂对比热容的影响很小.

To investigate the influence of heat capacity under low temperatures of transitional and envi- ronmental friendly polyurethane foam on thermal insulating equipment design, an adiabatic calorimeter was set up. A series of measures were adopted to decrease the heat leakage to maximum extent. With the calorimeter, the specific heat capacities of PU foams blown with CFC -11, HCFC -141b and HFC - 245fa were measured respectively in the temperature range from 60 K to ambient condition. The results show that the specific heat capacities increase with the increasing of temperature. For the same blowing a- gent, the specific heat capacity increases when the density increases, but the influence extent gets sligh- ter at low temperatures. For the same density, the descending sequence of specific heat capacity of three PU foams is HFC -245fa, HCFC - 141b and CFC - 11, while the influence of blowing agent is negli- gible in low temperature range.