Study On The Performance Of Seawater Heat Exchanger In Low Latitude Lsland Reef Area

Low-latitude areas generally distribute in the regions with the latitude range of 30degrees to 40 degrees,including the tropical and subtropical.Due to the unique geographical location,it is an area with rich solar radiation,a uniform climate change and a great deal of biological resource.Low-latitude islands and reefs are surrounded by oceans and have abundant seawater resource.Low-latitude area is located in the south of china with a large number of islands.The sea water resource is widely distributed.Sea water temperature in a certain depth is stable because of small impact of air temperature.It is an obvious advantage to act as ideal heat sink of condenser.Spiral pipe heat exchangers have been widely used as a key component of the heat pump system,for its high heat transfer efficiency,compact structure and convenient processing.Therefore,simulation of the heat transfer performance of spiral heat exchanger in low-latitude and its experimental test are done in this paper.Moreover,this paper focuses on the influence of the coupling between the structure of the tube and the flow inside/outside the tube on its transfer performance,based on the stability and lower seawater temperature than the air temperature in summer.Firstly,the mathematical model of the spiral heat exchanger in the seawater heat exchanger was set up in the summer condition,and the seawater hydrology condition is tested in a certain coastal city in southern China.In summer conditions,the temperature distribution and velocity distribution of seawater along the vertical direction were measured,and the same with the temperature and humidity above the sea surface.The test results are sequentially substituted into the corresponding CFD numerical model,the numerical simulation of the convective heat transfer process in the tube inside and out.Secondly,the impact of the diameter of the pipe,length of the pipe,the velocity of the inlet,the thermal conductivity of the heat exchanger,the curvature ratioδand the dimensionless pitch H_o on the heat transfer characteristics of the heat exchanger were studied by means of numerical simulation.And the variation law of the surface heat transfer coefficient inside and outside the cast pipe in summer condition was simulated.When the outside flow velocity range is 0.1~0.2 m/s and the flow velocity range is0.2~0.6 m/s under simulating conditions,the heat transfer coefficient of the outer surface of the tube is smaller than that of the tube,indicating that the thermal resistance is mainly concentrated outside the tube.The main influencing factors of the heat exchanger is outside the tube.At last,the correlation formula of the heat transfer inside and outside the tube of spiral heat exchanger was given and the influencing factors were analyzed,taking the seawater heat exchanger in the low latitude island reef in southern China as an example.The structural parameters of seawater heat exchangers were analyzed according to the optimization theory,and evaluate was evaluated.Combined with the field test data and the simulation data analysis.An optimal structural of the spiral heat exchanger which can be used in the practical engineering was proposed.