单螺旋吹风式速冻装置料口改进的实验研究

从理论上分析了影响单螺旋吹风式速冻装置料口热质交换的主要因素是料口内外的热压压差和风压压差.在实验的典型工况下,热压和风压压差引起的冷量损失分别是3.90KW和1.48KW,均大于围护结构的热负荷(1KW).实验研究发现料口处风压和热压压差同时存在并相互叠加,提出了在进、出料口之间加装隔板的改进方案可以减小热压压差,料口平面与动压方向平行可以减小风压压差,料口处的热压与风压方向相反可以起到减小料口热质交换并减少冷量损失的作用.对比实验结果表明,料口处的冷量损失与料口处的风速成正比,风速度减小1/3左右,料口处的冷量损失减小为原来的1/3左右.

Modification of Entrance and Exit of Single Spiral Quick-freezing Installation

The pressure-difference caused by heat and wind are the main factors affecting mass and heat transfer of single spiral quick-freezing installation. At the experimental condition, the cooling loss caused by heat pressure-difference and wind pressure-difference was 3.90kW and 1.48kW respectively, which was larger than the heat load of fender structure (1kW). The results show that heat pressure-difference and wind pressure-difference exist simultaneously and superpose each other. Installing a baffle plate between the entrance and exit can decrease heat pressure-difference. It can reduce wind pressure-difference to make the entrance and exit face paralleling the position of dynamic pressure. The converse interaction of heat pressure and wind pressure is used to modify mass and heat transfer of the entrance and exit and cooling losses. The compared results show that the cooling loss is directly proportional to velocity. When the velocity is reduced 1/3 than the original, the cooling loss is reduced the same ratio.