Study On Technology Of Solar Drying For Crystal Copper Sulphate

Drying is one of the most important working procedures in the production process. But at the same time, it requires large quantities of energy and causes serious pollution to the environment. And the solar energy, as a kind of the clean, green renewable energy is the substitute of the conventional energy. It was utilized to heat the drying medium. This technology can solve the problem of high energy consumption and pollution in the drying process. It has obvious advantage in environmental protection and energy saving. Concerned with the problem of high energy consumption and serious pollution existing in the process of drying for inorganic salts, and combining the projects of enterprise, this paper put forward the technology of solar drying for crystal copper sulphate. In addition, the process of heat and mass transfer in copper sulphate under heating condition of solar radiation were analyzed at the angle of experiment and theory.According to the requirements of characteristic and drying condition of the crystal copper sulphate, a series tests were conducted with a self-designed solar drying device to study the technological condition of it. The results proved that using solar energy to drying crystal copper sulphate is feasible. The test data also showed that the intensity of solar radiation, environmental temperature, humidity and the stack thickness affected the drying process. Among them, the drying rate was obviously affected by environmental relative humidity. The intensity of solar radiation had significant influence on the temperature changes. By regression of the experimental data, the thin layer drying model of crystal copper sulphate was built. The results showed that the Page equation gave the best fit to experimental data.Based on the analysis of the heat and mass transfer in copper sulphate under heating condition, one dimension and transient model of heat and moisture transfer was established. And some parameters involved such as thermal conductivity, thermal diffusivity, density, specific heat, heat transfer coefficient, radiative heat-transfer coefficient were determined by the empirical formula and test.By the aid of the PDE tool box in MATLAB and ANSYS software, the numerical simulation on the transient temperature and humidity field of copper sulphate under heating condition was carried out according to the given boundary. And the comparison between experimental and numerical results showed a good coherence, which proved the model coincide with the drying mechanism. In addition, the influencing factors on heat and mass transfer in copper sulphate were analyzed quantitatively by numerical simulation.In addition, comparing with the mechanical dehydration, the energy-saving benefit and environmental efficiency of the solar house (200m2) with an output of 2 tons per day are evaluated. The results of comparison showed that the solar house system resolved the problem of noise and dust, and saved 12.85 tons coal and 35200 kW·h electricity consumption every year. At the same time, it created 80.02 tons less of total CO2 emission amount. In short, the environmental effect of this system is significantly great.This study provided theory evidences and technical supports for the optimization of process parameters during drying. This is also the significance of this paper.