Heat Or Mass Transfering Mechanism And Temperature Field Simulation Of Sodium Silicate Sand Hardened By Microwave

The microwave heating sodium silicate sand process can exert adequately thebonding potential of sodium silicate binder, which makes the sodium silicate binderadding quantity decreased greatly, so that the collapsibility and reclaim-ability of theused sand are greatly improved.In addition, the process has a series of advantagesincluding short hardening time, high compression strength, good control performance.However, the basic research on the microwave hardening sodium silicate sand processis rare and many experimental studies lack of the oretical basis. Therefore, study ofthe mechanism of heat and mass transfer and characteristics of temperature field ofsodium silicate sand hardened by Microwave heating becomes very important, whichcan make great strides in the practical application of sodium silicate sand hardened bymicrowave heating.A kind of temperature measurement device which can be used in electromagneticfield to measure the fixed-point temperature was built with fiber optic temperaturesensor and the internal temperature of sodium silicate sand samples with different sizeand shape heated by microwave were measured. The results show that: there is apositive temperature gradient from inside to outside within the samples of sodiumsilicate sand samples hardened by microwave; the position of highest temperature isnot in the center of the samples; size and shape of the sample have no affect on itsinternal temperature gradient.Under the existing microwave theory and research data, and consider thecharacteristics of sodium silicate sand, heat or mass transfering mechanism of sodiumsilicate sand hardened by microwave was pre-hardened and the corresponding heat ormass transfering mathematical model was derived. The electromagnetic-heat transfermodel is a combination of this model and electromagnetic model.Simulated thetemperature field of different sizes of cylinder orcube sodium silicate sand sample,basing on this mathematical model and using the finite-difference time-domainmethod and the software “MATLB”. The simulation results were compared with experimental results and the correctness and rationality of the heat or mass transferingmechanism of sodium silicate sand hardened by microwave were validated.The influence of microwave heating sodium silicate sand process parameters onthe characteristics of temperature field and the performance of sodium silicate sandwas studied in this paper. The results show that: the temperature influence on themicrowave curing process parameters, including microwave heating time, microwaveheating power and water glass dosage; process parameters used in the internaltemperature did not affect the distribution of sand; microwave curing temperature andthe impact of sodium silicate is sodium silicate dosage sand performance of the mainfactors. And accordingly, the microwave hardening sodium silicate sand processproposed preliminary optimization.