共查询到16条相似文献,搜索用时 109 毫秒
1.
2.
本文着重介绍了真空气化冷却原理,真空气化冷却装置及其操作技术,影响真空冷却装置及其操作技术,影响真空冷却效果的主要因素等问题。 相似文献
3.
利用圆柱型的熟肉为实验材料,通过实验验证了真空冷却过程中水分迁移的数学模型。结果发现:产品在70min内从70℃被冷却到5℃。当真空冷却结束时,产品中心和表面的实验温度分别是7.01。c和3.98℃,对应的产品的中心和表面的模拟温度分别是6.97℃和3.78℃。真空冷却实验过程中,产品的平均水分含量从72.60%降到61.03%。模拟过程中,产品的平均水分含量从71.00%降低到62.37%。模拟结果显示真空冷却的质量损失为8.63%,然而实验过程中真空冷却的质量损失为11.57%,其偏差在3%左右。模拟结果与实验结果基本一致,建立的数学模型能够正确地预测真空冷却过程中温度、压力和水分含量的变化过程。 相似文献
4.
真空冷却技术及其在食品工业的研究和应用 总被引:12,自引:0,他引:12
本文对真空冷却原理和系统作了简要介绍,分析了真空冷却技术存在的优缺点.论述了国内外真空冷却技术的研究进展,举例介绍其在食品工业的应用情况,最后指出真空冷却技术今后的研究趋势. 相似文献
5.
本文提出了采用”加压浸液冷却技术”,“喷液—浸被冷却技术”、“加压气—液(雾)混合喷射冷却技术”实现扩大真空淬火冷却速度控制范围的新观点及具体措施。本文还认为解决真空渗碳中“碳黑污染”、“尖角过渗’现象的根本方法是:在工艺方面引入平衡渗碳工艺;在设备方面要研制非碳质元件真空渗碳炉。 相似文献
6.
7.
食品真空冷却的机制、特性与实验装置 总被引:12,自引:0,他引:12
本文分析了食品中水蒸汽压、比热容及单位质量失水1%获得温降的计算方法;建立了食品真空冷却过程的传热、传质微分方程与积分方程;分析了真空冷却技术的优点及适用性,并简要介绍了真空冷却实验装置及可深入研究的几个方向 相似文献
8.
9.
真空冷却技术具有降温速度快、运行能耗低等优点,在食品冷链中得到了应用并迅速发展。本文以蒸煮肉制品为研究对象,开展蒸煮肉制品真空冷却效果实验,分析不同冷阱温度对冷却速率、质量变化和真空室内压力对冷却效果的影响。结果表明:不同的冷阱温度对蒸煮肉制品冷却速率、冷却前后的质量变化,以及对冷却过程中真空室内的压力产生不同的影响。另外,并非冷阱温度越低冷却效果越好,实验对比了冷阱温度为-15℃、-25℃和-35℃下的真空冷却过程,冷阱温度的最佳值为-25℃,冷却时间最少为320s。 相似文献
10.
11.
Cooling rate and heat transfer characteristics of cooked meats using four different cooling systems of vacuum cooling, air blast cooling, water immersion cooling and slow air cooling were investigated. The experimental results show that only the vacuum cooling can achieve the requirement of cooling the cooked meats from about 74 to 10°C within 2.5 h. The vacuum cooling shows different heat transfer characteristics during the cooling process, as compared with other cooling methods. Vacuum cooling rate is controlled by the evaporation rate of water from the cooked meats, while the cooling rates of the other three cooling methods are governed by the thermal conductivity of the cooked meats. Therefore, it is impossible for air blast, water immersion and slow air cooling to obtain high cooling rates since these three methods are different only in the convective heat transfer from the surface of the cooked meat to the cooling medium. 相似文献
12.
13.
A mathematical model is developed to analyse the performance of a vacuum cooler. The model is based on the mass conservation of air and vapour in the vacuum chamber. In the chamber, the vapour evaporated from foods under the vacuum and the vapour removed by the vapour-condenser and vacuum pump contribute to the variation in the vapour partial pressure, and the ingress air and the air released by the pump cause the change of air partial pressure. Experiments were carried out on vacuum cooling of water to validate the model. The predicted vacuum pressure and temperature histories are compared with the measured values. The maximum deviation between the predicted and measured vacuum pressure is within 110 Pa (for the chamber pressure between 12,000 and 2200 Pa), while the maximum deviation between the predicted and measured temperature of water is less than 2 °C. The model can, therefore, be used to predict the transient vacuum pressure profiles for analysing the vacuum cooling process of foods such as cooked meat. 相似文献
14.
2010年上海世博会期间,上海食品的质量与安全是关系到广大来宾和游客健康的大问题,该文主要阐述了食品从"源头"到"餐桌"全过程的安全检测与以真空冷却为主的食品保鲜技术,分析真空冷却工作原理、特点,以及在果蔬、生鲜食品和熟制调理食品的具体试验应用,还介绍了清洁蛋的生产和保鲜。 相似文献
15.
16.
The finite element method is used to analyse the two-dimensional transient heat transfer problem for cooling cooked meats with an ellipsoid shape under different environments offered by slow air, air blast and water immersion cooling units. The variations in physical properties of the cooked meat and in operating conditions during the cooling processes are included in the model. The models are solved by a user-friendly computer program developed by the authors. The numerical solutions are compared with the experimental results. The comparison shows that the maximum deviation between the predicted and experimental core temperatures for all the cooling processes is within 2.9°C. 相似文献