In a recent contribution[1]to this journal,Guo and co‐workers reported on the design of a dual beam FT‐IR spectrometer system aiming,among others,at totally removing the contribution of gas‐phase species during ope...In a recent contribution[1]to this journal,Guo and co‐workers reported on the design of a dual beam FT‐IR spectrometer system aiming,among others,at totally removing the contribution of gas‐phase species during operando studies of heterogeneous catalytic reactions.The system consists of two identical cells located in two separate FT‐IR spectrometers,one being loaded with a catalyst wafer and the other one being empty and used as a reference signal.The exhaust gas of the sample cell is sent to the reference cell,both being heated up at the same temperature.Any indication on cell volume or the nature of the flow regime(e.g.,plug flow or continuously stirred tank reactor(CSTR))is not mentioned.展开更多
A mathematical model for one-dimensional heat transfer in pipelines undergoing freezing induced by liquid nitrogen is elaborated.The basic premise of this technology is that the content within a pipeline is frozen to ...A mathematical model for one-dimensional heat transfer in pipelines undergoing freezing induced by liquid nitrogen is elaborated.The basic premise of this technology is that the content within a pipeline is frozen to form a plug or two plugs at a position upstream and downstream from a location where work a modification or a repair must be executed.Based on the variable separation method,the present model aims to solve the related coupled heat conduction and moving-boundary phase change problem.An experiment with a 219 mm long pipe,where water was taken as the plugging agent,is presented to demonstrate the relevance and reliability of the proposed model(results show that the error is within 18%).Thereafter,the model is applied to predict the cooling and freezing process of pipelines with different inner diameters at different liquid nitrogen refrigeration temperatures when water is used as the plugging agent.展开更多
文摘In a recent contribution[1]to this journal,Guo and co‐workers reported on the design of a dual beam FT‐IR spectrometer system aiming,among others,at totally removing the contribution of gas‐phase species during operando studies of heterogeneous catalytic reactions.The system consists of two identical cells located in two separate FT‐IR spectrometers,one being loaded with a catalyst wafer and the other one being empty and used as a reference signal.The exhaust gas of the sample cell is sent to the reference cell,both being heated up at the same temperature.Any indication on cell volume or the nature of the flow regime(e.g.,plug flow or continuously stirred tank reactor(CSTR))is not mentioned.
文摘A mathematical model for one-dimensional heat transfer in pipelines undergoing freezing induced by liquid nitrogen is elaborated.The basic premise of this technology is that the content within a pipeline is frozen to form a plug or two plugs at a position upstream and downstream from a location where work a modification or a repair must be executed.Based on the variable separation method,the present model aims to solve the related coupled heat conduction and moving-boundary phase change problem.An experiment with a 219 mm long pipe,where water was taken as the plugging agent,is presented to demonstrate the relevance and reliability of the proposed model(results show that the error is within 18%).Thereafter,the model is applied to predict the cooling and freezing process of pipelines with different inner diameters at different liquid nitrogen refrigeration temperatures when water is used as the plugging agent.
