In this paper, the standard k-ε two-equation model is adopted to numerically simulate fully developed fluid flow and heat transfer in a spiral finned tube within a cracking furnace for ethylene manufacturing. By vari...In this paper, the standard k-ε two-equation model is adopted to numerically simulate fully developed fluid flow and heat transfer in a spiral finned tube within a cracking furnace for ethylene manufacturing. By variable transformation, the original 3-D problem is converted into a 2-D problem in spiral coordinates. The algorithm of SIMPLEC is used to study the fully developed fluid flow and heat transfer in the spiral finned tube at constant periphery temperature and constant axial heat flux. The computed results agree pretty well with the experimental data obtained from the industry. Further studies on the fluid flows and temperature profiles at different Reynolds numbers within straight and spiral finned tubes are conducted and the mechanisms involved are explored. It is found that with the spiral finned tube, pressure drop increases to a great extent whereas heat transfer tends to be decreased.展开更多
This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crysta...This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crystallizer has been designed, the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature. The model is developed based on the basic heat transfer equation, and by considering the solution's and the coolant's convective heat transfer coefficient(h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model. Consequently, the study found that the model helps in enhancing the PFC system.展开更多
The pitch of the spiral finned tube influences seriously to the acoustic resonance in the heat exchanger.In this research,the flow characteristics in relating to the aeolian tone from the finned cylinder are studied b...The pitch of the spiral finned tube influences seriously to the acoustic resonance in the heat exchanger.In this research,the flow characteristics in relating to the aeolian tone from the finned cylinder are studied by the numerical simulation.It is observed that the tonal noise generated from the finned tube at two pitch spaces.The ratio of the fin pitch to the cylinder diameter is changed at 0.11 and 0.27.The tone level increases and the frequency decreases with the pitch shorter.The separation flow from the cylinder generates the span-wise vortices,Karman vortices,and the separation flow from the fin generates the stream-wise vortices.When the fin pitch ratio is small,the stream-wise vortices line up to span-wise and become weak rapidly.Only the Karman vortices are remained and integrate in span.So the Karman vortex became large.This causes the low frequency and the large aeolian tone.展开更多
文摘In this paper, the standard k-ε two-equation model is adopted to numerically simulate fully developed fluid flow and heat transfer in a spiral finned tube within a cracking furnace for ethylene manufacturing. By variable transformation, the original 3-D problem is converted into a 2-D problem in spiral coordinates. The algorithm of SIMPLEC is used to study the fully developed fluid flow and heat transfer in the spiral finned tube at constant periphery temperature and constant axial heat flux. The computed results agree pretty well with the experimental data obtained from the industry. Further studies on the fluid flows and temperature profiles at different Reynolds numbers within straight and spiral finned tubes are conducted and the mechanisms involved are explored. It is found that with the spiral finned tube, pressure drop increases to a great extent whereas heat transfer tends to be decreased.
基金the financial support through Research University Grant and Fundamental Research Grant Scheme(Vot nos.04H46 and 4F224)Chemical Engineering Department,Universiti Teknologi PETRONAS for its support
文摘This study presents a novel design for a spiral finned crystallizer which is the primary element of progressive freeze concentration(PFC) system, which simplifies the setup of the conventional system. After the crystallizer has been designed, the research experiments have been conducted and evaluated through a thorough analysis of its performance by developing a mathematical model that can be used to predict the productivity of ice crystal at a range of coolant temperature. The model is developed based on the basic heat transfer equation, and by considering the solution's and the coolant's convective heat transfer coefficient(h) under the forced flow condition.The model's accuracy is verified by making comparison between the ice crystal mass' experimental value and the values predicted by the model. Consequently, the study found that the model helps in enhancing the PFC system.
文摘The pitch of the spiral finned tube influences seriously to the acoustic resonance in the heat exchanger.In this research,the flow characteristics in relating to the aeolian tone from the finned cylinder are studied by the numerical simulation.It is observed that the tonal noise generated from the finned tube at two pitch spaces.The ratio of the fin pitch to the cylinder diameter is changed at 0.11 and 0.27.The tone level increases and the frequency decreases with the pitch shorter.The separation flow from the cylinder generates the span-wise vortices,Karman vortices,and the separation flow from the fin generates the stream-wise vortices.When the fin pitch ratio is small,the stream-wise vortices line up to span-wise and become weak rapidly.Only the Karman vortices are remained and integrate in span.So the Karman vortex became large.This causes the low frequency and the large aeolian tone.
