| Under the national energy saving and emission reduction situation, the development of renewable energy is the effective way of releaseing national energy shortage, adjusting the un-reasonable national energy structure, environmental protection, and is the only way of society and environment sustainable development.Compared with the air temperature, the temperature of river water is more stable,higher than air temperature in winter and lower in summer, and is a better cold and heat source used in building. Basing on the detailed investigation of Yangtze River water source in Chongqing,P.R.China, the technical route and key technology of river water source heat pump are studied.Using turbulent flow, computational fluid dynamics, two-phase flow and convection heat exchange theory, the heat exchanger used by river water source heat pump is studied theoretically and experimentally, which is a key technical problem of the development of river water source heat pump technology. Research methods, contents and Achievements are as follows:Hourly, daily and monthly average water temperature of Yangtze River in Chongqing,P.R.China are investigated and analysed Detailedly. The results show that the water temperature fluctuation is below 0.5℃, river water is a better cold and heat source than air , whose temperature fluctuation is larger than 10℃.Yangtze River cross section water temperature is well distributed. The quality problem is that river water contains much sediment and suspended matter. Yangtze River suspended sediment is mainly silt and clay. The formation of Three Gorges Reservoir Region has little influence on Yangtze River water level in Chongqing, P.R.China. So the water qulity changes little.By analysis technical route, energy saving and environmental protection of river water source heat pump system, the open-direct system of reasonablely developing of river water source heat pump technology is presented. Open-direct river water source heat pump system could save 33% energy than chiller and gas-fired boiler system, and 40% than air source heat pump system. River water source heat pump system can release the urban heat island effect because of the river water fluidity.The motion law of river sediment particle is basis of the river water two-phase flow research. The particle motion differential equation is analysed detailedly and the three-dimensional direct numerical method of particle motion differential equation is established. the settlement regularity of particle under non-linear drag force, Basset force and virtual mass force is analysed. By analysing magnitude of resistance force and lift force, the results show that the inertial force, drag force, pressure gradient foree, gravity alse with Basset, virtual mass force should be considered in particle-liquid motion. The Saffman force and Magnus force is only significant near wall.Using the large eddy simulation and particle direct simulation, the diffusion of particle in sudden expansion pipe is modeled. The results show that the diffusion degree of particle decreases with increase of St P number. Because of turbulence effect,the small particle can be taken more easily .Using the first and the second laws of thermodynamic, the entropy generation analysis, the influence of fouling on performance of convection heat transfer process inside pipe is analysed. Entropy production increased with the formation of fouling and caused the irreversibility of convection heat transfer process increased.Based on the water quality characteristics of Yangtze River, the heat exchanger type used in river water source heat pump is analysed and discussed, heat exchanger type used in large unit(patent application number 200810069811.1) and double pipe heat exchanger used in middle and small unit is presented.The flow,heat exchange and two-phase flow inside semi-annulus reentry pipe, which affected the sediment separation in pipe double pipe heat exchanger, is simulated numerically. The results show that secondary flow phenomenon is significant in semi-annulus reentry pipe. The performance of convection heat transfer will increase because of secondary flow phenomenon. Using two-fluid continuum model,the flow of the river water with sediment in semi-annulus reentry pipe of various curvature is simulated. The results show that separation of sediment has minimum when R/r ranges from 10 to 40.Using smooth inner wall and spiral groove exine pipe, whose R/r is 12, the experimental double pipe heat exchanger is designed. With numerical method, the heat transfer performance, resistance and two-phase flow of heat exchanger are analysed.the heat transfer performance and resistance analysis show that the CFD technology could meet heat exchanger design engineering application and could be used as computer assistant design reference. The result of two-phase flow simulation shows that the heat exchanger is not blocked by sediment.To validate numerical simulation result, the separation and blocking of heat exchanger is studied experimentally. Experimental results show that there are not blocking phenomenon caused by the sediment separation.At last, using the designed heat exchanger, the heat pump unit is studied experimentally in winter and in summer. The heat exchanger is not blocked and the heat pump unit operated well, it can be applied and popularized practically.
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