The Research And Development Of Heat Exchanger For Cold Energy Recovery In The Thawing Of Aquatic Product

For the current seawater heat exchanger is expensive,easy corrision and fouling.Compare to it,the exchanger in thaw water has not report,it is important to recovery the thaw water energy.It has 3.87×105KJ cold energy per ton can be used to industry to save 107.5electrical degrees.Thaw water has salt,protein and microbial.So it has the problem of how to solve the microbial of peotein,the fouling and water mixed.There are more demanding than sea water heat exchanger.So we should develop a heat exchanger according to the characteristic of thaw water,By comparision,the plate heat exchanger is fittable,using CFD to design the structure and analysis the fluid,and choose the corrugated plate.By numerical simulation to find the preferable design parameter.Through the experimental test the plate heat exchanger has a high heat tranfer efficiency.To observe the corrosion and fouling conditions of the PHE.It indicated that the plate has no serious corrosion,but some dirt microorganisms attached.This paper adopts join pharmacy or inoculation the steel microbial to reduce the corrosion rate.The experimental show that the structure can prevent the mixed of thaw water.It also verification the consistent between the numericial simulation and the experiment. Overall,achieved the desired effectThe main work as follows:1) By comparing various types of heat exchanger,comprehensive survey from aspects of applications,advantages and disadvantages,the heat tranfer efficiency and economic benifits.Eventually selected the PHE.Introduces the principle of the PHE for the corrosion,dirt principles and conditions for microbial growth.Proposed solution to the corrosion,dirt and microbial growth.2) A preliminary design for specific condition of PHE,innovate the local structure of the plate,select components, check its strength and stiffness of the structure.3) Through simulaion,establish a link between corrugated inclination β、ripple height h, ripple spacing γ and the pressure drop Ap and the Nusselt number Nu,which has good effect of heat tranfer and small resistance.At this time,the PHE has a better heat tranfer performance.The parameter is the corrugated inclinationβ≈60°,ripple height h=4mm or h=5mm,ripple spacing γ=10mm or γ=11mm.4) Through the experiment,compared the experimental results with the simulation results in two ways.First,compared to the inlet flow and outlet temperature of the cold and hot fluids.Second,compared to the inlet flow and pressure drop of cold and hot fluids.By comparing the two groups,it shows both the outlet temperature and pressure drop increases with increasing volumetric flow rate. The experimental results are consistent with the simulation results.By processing the experimental data,the heat tranfer efficiency is 83.7%,the heat tranfer coefficient is 2494.5W/(m2·K),indicating that it is indeed a highly efficient heat exchanger.5) Through the corrosion and fouling experiment.Get the fouling resistance with the time changing.The fouling resistance is 5.5×10-5W/(m2·K).By macroscopic observation that there is no more serious corrosion,after sixty days,the amount of corrsion is 0.04mm.The corrsion rate is 0.00133mm per day.the some microbes dirt adhesion to the plate.Measure the thaw water the microbial content islOcfu/ml.About ten percent of the before.Achieved good results by add chemical agent.By considering the structure,cost,efficiency to determine the plate heat exchanger,which have some anti-corrosion and anti-fouling ability. On the whole,has reached the expected goal.