Theoretical And Experimental Simulations On Heat And Mass Transfer In A Marine Farming Pond

Mariculture is a production mode which using sea water to feed and breedeconomic marine organism, it is one of important ways for human being to use marineresources directly and develop marine aquaculture. In recent thirty years, mariculturehas developed fast in China, China producing almost two-thirds of maricultureproductions in world is a developed country in mariculture field. A lot of data showsthat energy cost takes the highest rate of total cost for a factory Marine aquaculture,and becomes the most important factor on restricting the development of factoryMarine aquaculture in China. With the trend of thoroughly implement of energysaving laws in recent years, it becomes necessary to do some research works on themechanisms of heat and mass transfer in a mariculture pond for achieving the goal ofreducing the energy consumption.The heat and mass transfer mechanisms in a marine farming pond arecomplicated. In the thesis, an experimental simulation was conducted, some factorssuch as the temperature of hot water supply, the ambient air temperature and humidity,brine concentration and so on on the temperature distribution in the pond wereinvestigated. The heat balance of the simulated mariculture pond was obtained. Inaddition, flow visualization has been done, and numerically simulation using LatticeBoltzmann Method (LBM) for modeling the heat and mass transfer in the pond wascarried out.In the experiment, a plexiglass pond with600mm in diameter and400mm inheight was made to simulate the mariculture pond. Firstly, the heat balanceexperiment was conducted acounting for the boundary heat loss and the latent heat ofvaporization from the pond water surface, of which relative portions at varioussituations are obtained. The pressure difference between surface vapor and air can becalculated by the measured temperature and air humidity. The influence relationshipbetween pressure difference and evaporation rate is analyzed, we also contrast ourexperiment result with former schol’ars, the contrast results show good consistency.The temperature distirbution in pond is measured under different temperature of watersupply conditions, the temperature of water supply mainly influence the absolutetemperature of water in pond while has a little influent on temperature difference of water in pond, the natural convection of water is intense as the uniformity of temperature distribution shows, we also use infrared thermometer to measure the temperature distribution of surface. Natural convection of fresh water is little stronger than saline water, it’s worth noting that the uniformity of concentration of saline water has great influence on the strength of natural convection, and heat transfer and mass transfer have close influence relationship with each other.As a theoretical investigation for LBM free surface method, a2D Dam-Break model is established and is validated in both reliability and accuracy by comparing the results with those of previous works. Then a2D water pond model is established and solved by using LBM method, the influences of different Ra numbers on temperature and concentration fields and velocity vector field are analyzed. Finally, some recommendations or suggestions for improvement in the follow-up study of this subject are proposed.