Inspired by the property diagrams in thermodynamics,which distinctly reflect the performance and characteristics of thermodynamic cycles,we establish a state equation for heat motion and introduce a two-dimension prop...Inspired by the property diagrams in thermodynamics,which distinctly reflect the performance and characteristics of thermodynamic cycles,we establish a state equation for heat motion and introduce a two-dimension property diagram,T-q diagram,in heat transfer to analyze and optimize the performance of heat exchangers,where heat flow is a state parameter for heat motion.According to the property diagram,it is convenient to obtain the influences of heat exchanger area,heat capacity rate and flow arrangement on the heat transfer performance during the analysis of heat exchangers and their networks.For instance,when analyzing the heat exchanger network in a district heating system,it is obvious to find that:if both the heat demand and the indoor air temperature in each branch of the network are the same,the total area of heat exchangers,the flow rate of water and the return water temperature in each branch are all the same;if the indoor air temperatures in different branches are different,the temperatures of the waters after flowing through different branches are different,which means that the mixing process of return waters with the same temperature is not an essential requirement to realize the best performance of district heating systems.展开更多
Cooling water is an important part in a Spallation Neutron Source target cooling system, but the unstable vortexes at the exits of the slits between every two tungsten target slices have a negative impact on the stabl...Cooling water is an important part in a Spallation Neutron Source target cooling system, but the unstable vortexes at the exits of the slits between every two tungsten target slices have a negative impact on the stable running of the target system. We apply the field synergy principle for fluid flow to obtain the optimal flow field, which has a uniform velocity distribution without eddy, and then, optimize the geometrical structure of the cooling water flow channel based on the optimal flow field. The results show that when the cooling water flows in the optimized channel, the eddy sizes decrease, the time fluctuations of velocity and pressure almost vanish, and the volume flow rates of the cooling water in each parallel slit are uniform. Therefore, it effectively improves the running stability of the target system with the premise of satisfying the target heat load.展开更多
基金supported by the National Natural Science Foundation of China(51006060 and 51036003)the Foundation for the Author of National Excellent Doctoral Dissertation of China
文摘Inspired by the property diagrams in thermodynamics,which distinctly reflect the performance and characteristics of thermodynamic cycles,we establish a state equation for heat motion and introduce a two-dimension property diagram,T-q diagram,in heat transfer to analyze and optimize the performance of heat exchangers,where heat flow is a state parameter for heat motion.According to the property diagram,it is convenient to obtain the influences of heat exchanger area,heat capacity rate and flow arrangement on the heat transfer performance during the analysis of heat exchangers and their networks.For instance,when analyzing the heat exchanger network in a district heating system,it is obvious to find that:if both the heat demand and the indoor air temperature in each branch of the network are the same,the total area of heat exchangers,the flow rate of water and the return water temperature in each branch are all the same;if the indoor air temperatures in different branches are different,the temperatures of the waters after flowing through different branches are different,which means that the mixing process of return waters with the same temperature is not an essential requirement to realize the best performance of district heating systems.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51006060, 51036003)the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No.201150)
文摘Cooling water is an important part in a Spallation Neutron Source target cooling system, but the unstable vortexes at the exits of the slits between every two tungsten target slices have a negative impact on the stable running of the target system. We apply the field synergy principle for fluid flow to obtain the optimal flow field, which has a uniform velocity distribution without eddy, and then, optimize the geometrical structure of the cooling water flow channel based on the optimal flow field. The results show that when the cooling water flows in the optimized channel, the eddy sizes decrease, the time fluctuations of velocity and pressure almost vanish, and the volume flow rates of the cooling water in each parallel slit are uniform. Therefore, it effectively improves the running stability of the target system with the premise of satisfying the target heat load.
