Analyswas On Flow Field Of Ice Tank And Optimization Design Of Ice Tank Structure

Ice block machine was a kind of ice making equipment which used salt water as secondary refrigerant, the block ice it produced was dense, uneasy to melt, storage and transport conveniently. Ice block machine was the main ice making mean on fisheries, but exist some disadvantages, such as low efficiency and large energy consumption. In this paper, ice block machine of 10t/d products as research object was sampled from an equipment company. The arrangement modes, cross section forms of ice cans of ice tank, water chamber structure forms of ice tank and structure forms of evaporator impacts on flow field of ice tank was simulated with CFD software. The velocity, temperature and pressure field of salt water in ice tank was analysed and compared to optimize the structure of ice tank. The conclusions were as follows:The arrangement modes of ice cans impacted flow field of ice tank a lot. Rectangular, approximate elliptic and diamond ice cans with in-line arrangement, velocity of salt water in longitudinal separation of ice cans was uniform and respectively 0.25~0.4m/s, 0.2~0.35m/s and 0.15~0.25m/s, salt water in lateral separation of ice cans was almost stationary, velocity of salt water in which was respectively 0~0.05m/s, 0.05~0.1m/s and 0~0.1m/s. While arrangement mode of ice cans changed to staggered arrangement, salt water flow around ice cans, disturbance resistance of salt water was enhanced, flow velocity of salt water in lateral and longitudinal separation of ice cans was relatively more homogeneous and respectively 0.1~0.35m/s, 0.05~0.2m/s and 0.02~0.25m/s, and temperature rise of salt water was relatively more higher, it rised respectively from 0.3~0.35℃, 0.2~0.25℃ and 0.25~0.3℃ to 0.4~0.45℃, 0.25~0.3℃ and 0.3~0.35℃, but resistance of salt water was relatively increased respectively from 400~600Pa, 400~600Pa and 800~1000Pa to 2000~2200Pa, 600~800Pa and 1000~1200Pa. Staggered arrangement was beneficial to heat transfer enhancement of salt water and ice cans, improve heat exchange efficiency of ice tank, even icing rate of ice cans, shorten icing time, save power consumption of system and improve economic benefit of system.The cross section forms of ice cans impacted flow field of ice tank a lot. While section type of ice cans was changed from rectangular to approximate elliptic, whether ice cans with in-line arrangement or staggered arrangement, disturbance resistance of salt water was the most strongest, while ice cans with in-line arrangement, velocity of salt water in lateral separation of ice cans was relatively higher and was about 0.05~0.1m/s, resistance of salt water was relatively lower. While ice cans with staggered arrangement, flow velocity of salt water in lateral and longitudinal separation of ice cans was relatively more homogeneous. Icing rate was more uniform, which was beneficial to shorten icing time and improve heat exchange efficiency of ice tank.The water chamber structure forms of ice tank impacted flow field of ice tank in some condition. In case of ice tank with rectangular water chamber exist speed stagnation region in score water chamber and collecting water chamber, while water chamber was changed to triangle, speed stagnation region was decreased, velocity distribution of salt water in ice tank was more uniform.The structure forms of evaporator impacted flow field of ice tank a lot. In case of existing evaporator without baffle plate, salt water transversal flow over evaporator pipe, velocity of salt water was about 0.4m/s, velocity distribution of salt water was more uniform. Drop of temperature of salt water was about 0.3~0.4℃, and resistance of salt water was relatively smaller and was about 300 Pa. In case of evaporator equipped with baffle plate, salt water longitudinal flow over evaporator pipe, drop of temperature of salt water was relatively higher and was about 0.9℃, disturbance of salt water was enhanced and was about 7000 Pa. Baffle plate was good for heat transfer enhancement between salt water and evaporator, shorten icing time, save power consumption of system, improve economic benefit of system.Resistance of refrigeration of evaporator changed from 10 tube passes to 2 tube passes was analysed and compared by calculation method in this paper. In case of existing evaporator changed from 10 tube passes to 2 tube passes, diameter of evaporator pipe was 0.75 times of original, resistance of refrigerant in evaporator was about 8.94% of original, the heat transfer area density of evaporator was increased about 40%, compressor power was decreased about 28.5%, refrigeration coefficient was rise from 2.958 to 4.135. 2 tube passes structure of evaporator was beneficial to higher heat transfer effect, save cooper pipe materials, lower compressor power, higher refrigeration coefficient of system and improve economic benefit of system.