| Freshwater fish production reached more than 40% in the yield of the fishery industry in China. But its aquatic products deep processing is less than 30%, compared with the developed countries, whose deep processing of aquatic products is up to 50%, the existence problem is lack of deep processing ability. Therefore, new technology research and development of the freshwater fish drying equipment is conductive to the development of the whole industry. In this paper, based on the radiation drying technology and combined the heat pump technology with the radiation drying technology, a preliminary study for the design, manufacture and drying process of the test equipment were carried out. The main contents and conclusions of this study were summarized below.1. According to the mechanism of radiation drying and the structural analysis of the related equipment, we obtained the radiation distance of 300-400mm. And get the basic dimensions of the oven body and radiant panel according to the radiation distance. The intensity static stress analysis of radiant panel by using the SolidWorks 3D modeling was conducted. The analysis result showed that using strong gluten layout design programs can meet the experimental facilities requirement. Ensure the connect scheme of the radiant panel was install in series. After calculating we obtained that the radiation heat transfer coefficient of radiant panel is 325, the area of radiation is 0.49m2, and hot water flow is 0.477t/h.2. The radiation temperature of the test device is 65℃, material temperature is 27℃ has been determined. We obtained that the heat radiation heat transfer power is 1114W. As for heat pump system, we select the environmentally friendly refrigerant R134a, which evaporation temperature is 70℃, the condensing temperature is 10℃. Using the CoolPack soft to analyze heat pump system of pressure enthalpy cycle, we obtained that:W=0.7kW,QE=1.352kW. According to the characteristic parameters of the heat pump cycle system, the selection and calculation of key components (a compressor, condenser and evaporator) were conducted, and debug the entire experimental device in the end.3. Using the above experimental device, the single factor experiment study on the drying characteristics of freshwater fish by combining radiation with the heat pump was carried out, we confirmed that the radiation temperature, fish slice thickness, drying chamber temperature have effect to freshwater fish drying rate, rehydration ratio and sensory evaluation. The results show that the radiation temperature has significant effect on the drying time, but has no significant effect on the rehydration ratio and sensual assessment. In the range of 2mm-4mm, the slice thickness have a significant effect on drying time and rehydration ratio, and the drying chamber temperature has no significant effect on the drying time, rehydration ratio and sensory evaluation, which verified the feasibility of the test device.4. Determine the orthogonal experiment level and factors based on single factor experiment, and select the drying time, rehydration ratio, sensory evaluation value and average energy consumption of dehydration as measure index. Using the comprehensive balance method to analysis, and obtain the best technological parameters which that radiation temperature is 70℃, slice thickness is 4 mm and drying room temperature is 22℃. Utilizing Minitab software for variance analysis of orthogonal experimental results, ensure that the thickness has significant influence on the drying time and rehydration ratio and other factors had no significant effect on the quality of analysis and energy consumption, the ANOVA results are consistent with the comprehensive balance analysis. Under the condition of optimum technological parameters, the experimental results are as follows:the drying time is 11.5 hours, the rehydration ratio is 49.72%, sensory evaluation value is 88.0, the average energy consumption of dehydration is 1.81kg/kW-h, which save 36.46% energy than the hot air drying. |
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