In this work an experimental study combined with an analytical investigation for cooling superheated Carbon Dioxide （CO2） gas were carried out. This work is intended to be part of the super critical Gustav Lorentzen...In this work an experimental study combined with an analytical investigation for cooling superheated Carbon Dioxide （CO2） gas were carried out. This work is intended to be part of the super critical Gustav Lorentzen refrigeration cycle of CO2. Experimental and analytical works concentrated on heat transfer and pressure drop for single phase flow during gas cooling inside tubes filled with porous media. Analytical empirical correlations were formulated for the coefficient of convectional heat transfer and for the pressure drop. A comparison between experimental results and that obtained by developed correlations were carried out, and a comparison between these results and literature published ones were carried out too. The results of this research showed that for cooling process the proposed correlations were proved to be acceptably accurate for pressure drop with difference from experimental results of 2%, while for convective heat transfer the difference from experimental results reached about 3%. More than 90% agreement with literature results was obtained. This work can enhance the calculations of heat flux and pressure drop of gases flow inside porous media filled tubes, and can help in the design procedure of heat exchangers and cooling processes.展开更多
In this work, the easy to use, simple and direct equations were formulated and tested. These equations can be used to calculate the mean values of the heat transfer coefficients of inside tube flow during phase change...In this work, the easy to use, simple and direct equations were formulated and tested. These equations can be used to calculate the mean values of the heat transfer coefficients of inside tube flow during phase change. Analytical and experimental methods were used to correlate these equations. Two different forms were used, one for evaporation case and the other for condensation case. Carbon dioxide, CO2, was used as case study. Correlated values of the mean heat transfer coefficients （hcor,.） were compared with the experimental results （he^e） and with other published result, a good agreement was noticed. The resulted correlations can be used to simplify the design and performance studies of both condensers and evaporators.展开更多
Evaporative cooling is a widely used air cooling technique. In this method, evaporation of a liquid in the surrounding air cools the air in contact with it. In the current investigation, numerical simulations are card...Evaporative cooling is a widely used air cooling technique. In this method, evaporation of a liquid in the surrounding air cools the air in contact with it. In the current investigation, numerical simulations are carded out to visualize the evaporation and dynamics of tiny water droplets of different diameters in a long air duct. The effect of initial droplet size on the temperature and relative humidity distribution of the air stream in the duct is investigated. Three different initial conditions of air are considered to verify the influence of ambient conditions. Droplet spray patterns are also analyzed to identify the suitable locations for the spray nozzles within the duct. The resuits obtained are displayed in a series of plots to provide a clear understanding of the evaporative cooling process as well as the droplet dynamics within the ducts.展开更多
文摘In this work an experimental study combined with an analytical investigation for cooling superheated Carbon Dioxide （CO2） gas were carried out. This work is intended to be part of the super critical Gustav Lorentzen refrigeration cycle of CO2. Experimental and analytical works concentrated on heat transfer and pressure drop for single phase flow during gas cooling inside tubes filled with porous media. Analytical empirical correlations were formulated for the coefficient of convectional heat transfer and for the pressure drop. A comparison between experimental results and that obtained by developed correlations were carried out, and a comparison between these results and literature published ones were carried out too. The results of this research showed that for cooling process the proposed correlations were proved to be acceptably accurate for pressure drop with difference from experimental results of 2%, while for convective heat transfer the difference from experimental results reached about 3%. More than 90% agreement with literature results was obtained. This work can enhance the calculations of heat flux and pressure drop of gases flow inside porous media filled tubes, and can help in the design procedure of heat exchangers and cooling processes.
文摘In this work, the easy to use, simple and direct equations were formulated and tested. These equations can be used to calculate the mean values of the heat transfer coefficients of inside tube flow during phase change. Analytical and experimental methods were used to correlate these equations. Two different forms were used, one for evaporation case and the other for condensation case. Carbon dioxide, CO2, was used as case study. Correlated values of the mean heat transfer coefficients （hcor,.） were compared with the experimental results （he^e） and with other published result, a good agreement was noticed. The resulted correlations can be used to simplify the design and performance studies of both condensers and evaporators.
基金supported by the Ministry of Education, Science Technology (MEST) and Korea Institute for Advancement of Technology (KIAT) through the Human Resource Training Project for Regional Innovation
文摘Evaporative cooling is a widely used air cooling technique. In this method, evaporation of a liquid in the surrounding air cools the air in contact with it. In the current investigation, numerical simulations are carded out to visualize the evaporation and dynamics of tiny water droplets of different diameters in a long air duct. The effect of initial droplet size on the temperature and relative humidity distribution of the air stream in the duct is investigated. Three different initial conditions of air are considered to verify the influence of ambient conditions. Droplet spray patterns are also analyzed to identify the suitable locations for the spray nozzles within the duct. The resuits obtained are displayed in a series of plots to provide a clear understanding of the evaporative cooling process as well as the droplet dynamics within the ducts.
