冷饮厂制冷系统设计值得注意的几个问题

就制冷系统的设计,针对冷饮工厂的特点,提出了应该注意的几个问题。      

奶粉风力输送的几个问题

现代奶粉生产趋于自动化生产。粉从干燥塔出来到粉仓也采用了无污染的风力输送,以粉量为1000kg/h的输送量阐述奶粉风力输送过程中可能出现的一些问题。     

浅谈制冷空调的节能技术

节能减排是实现社会可持续发展的重要措施,而作为能耗大户的空调系统,其节能设计有着重要的现实意义。文章主要针对空调制冷系统的节能降低措施进行研究。     

浅谈制冷空调的节能技术

节能减排是实现社会可持续发展的重要措施,而作为能耗大户的空调系统,其节能设计有着重要的现实意义。文章主要针对空调制冷系统的节能降低措施进行研究。     

浅议当代住宅电气设计中几个值得注意的问题

随着经济和科技的不断发展,住宅电气设计早已不是过去的单一照明功能,而是朝着多功能方向发展。特别是当代家庭住宅中家用电器的增多,尤其是一些大功率家用电器走入千家万户,使得当代住宅建筑电气化程度越来越高,这也给住宅电气设计者提出了新的挑战。文章结合笔者的工作实践,就当代住宅电气设计中几个值得注意的问题谈几点个人看法,旨在抛砖引玉,期望与广大同行共同推动我国住宅电气设计又好又快的发展。     

罐装牛奶制冷的系统设计

<正> 牛奶场的罐装牛奶制冷由于其固有的性质是压缩机的一种恶劣应用场合。虽然其运行范围适应设计用于高温应用的压缩机的能力范围内,其设备的位置,安装和全年运行可能造成常规商用制冷应用所没有的潜在危险。 1.从进空罐的热牛奶到满罐时的4℃,负载变化极大。结果是蒸发器液体制冷剂的需要量变化很大,并且对压缩机电机可能有极端负载。 2.农村地区可能电力不足,且可能在最高需用电时电压降低。     

板式蒸发器设计应注意的几个问题

板式蒸发器的最大优点是体积较小,占用空间小;与管式降膜式蒸发器一样在负压下蒸发,属于低温蒸发,其主要形式有升膜式、升降膜式及降膜式三种,降膜式在国内还不多见。对升降膜板式蒸发器存在的问题及设计时应注意的事项进行了阐述。     

湿面压延机组设计中几个值得注意的问题

简述了在压延机组设计中，如何解决压辊数量、压面辊形状和齿轮参数等问题。     

微生物检测中几个值得注意的问题

本文就微生物检测好氧菌方面的取样、检测方法等几个易疏忽的问题进行探讨。     

远程控制系统在复烤厂中的应用

按照企业电控技改的原则 ,对烟叶复烤厂技改中生产线的电气控制方案进行综合分析和评价 ,以选择出最适合企业的控制形式。结合企业的实际情况 ,综合分析和评价后认为 :复烤厂电控系统适宜采用远程分站形式 ,配以标准化的编程 ,使设备控制层的程序规范化 ,便于现场设备和电控系统的维护与管理 ,提高和稳定产品的质量。     

智能在线设备监控系统在油脂工厂设备管理中的应用

阐述了智能在线设备监控系统在油脂工厂设备管理中的应用,并结合实际应用案例介绍了其在油厂维护中的具体应用方式。     

乳品厂新型CIP自动控制系统

为了顺应国内乳品厂原地清洗(CIP)工艺的不断发展，研制了新一代基于PLC控制器的CIP设备控制系统，本文介绍了该系统的原理、组成及应用。     

自行复叠式制冷系统毛细管的计算

在分析自行复叠式制冷系统热回路和力学回路的基础上,讨论了无回热毛细管液相段和两相段的计算方法,将微元长度方法拓展至非共沸混合制冷剂制冷系统无回热毛细管的长度计算.毛细管的计算长度与实验长度相比误差<5%,在工程可接受的范围内,因此,微元长度法可用于非共沸混合制冷系统毛细管的长度计算,减少自行复叠式制冷系统的实验工作量.     

用于食品冷冻温度控制的模糊控制系统设计

目的:提高食品进入冷冻隧道的速度控制回路和温度控制回路的设定值调整能力。方法:对传送带速度和温度控制回路进行了单独处理,设计用于食品冷冻温度控制的模糊控制系统。该控制系统包括用于食品传送带滚子转速的比例—积分—微分控制器、用于冷冻隧道温度调节的比例—积分控制器,并采用Takagi-Sugeno模糊控制器来设定温度调节比例—积分控制器的温度设定点。结果:待冷冻食品的质量流量从650 kg/h增加到700 kg/h、驱动辊的转速从1.62 r/min增加到1.75 r/min时,最终食品温度可快速恢复到约-18℃;食品入口发生+5℃的温度干扰时,模糊控制器动作,从而将食品的出口温度保持在预期值-18℃附近。结论:所设计的控制系统通过选择允许快速响应和相对较低超调的系统参数,可实现输出变量的值不会在设定值附近出现大幅波动。     

Farm and factory production of goat cheese whey results in distinct chemical composition

To analyze differences in fat and protein content in cheese whey (CW) manufactured in cheese-making factories and farms, goat CW samples were obtained from 60 cheese-making farms and 20 cheese factories. Gross composition of samples was analyzed by using an MIRIS device (MIRIS Inc., Uppsala, Sweden), whey protein composition was subjected to electrophoretic analysis, and fatty acid composition was analyzed via gas chromatography. Goat CW from farms contained higher dry matter content (70.6 vs. 50.8 g/L, farms vs. cheese factories, respectively) and a higher fat percentage (10.5 vs. 1.2% over dry matter, farms vs. cheese factories, respectively) than CW from cheese factories. Analysis of individual proteins showed that CW from farms contained higher concentrations of lactoferrin (0.4 vs. 0.2 mg/mL of CW, farms vs. cheese factories, respectively) and caprine serum albumin (0.6 vs. 0.4 mg/mL of whey, farms vs. cheese factories, respectively) than CW from cheese factories. No differences were observed in the fatty acid profile. The main fatty acids present in goat CW were C16:0, C18:1, C14:0, and C18:0. Thus, the origin of CW affects gross composition and the protein profile, but not the fatty acid profile.     

卷烟厂空调与制冷系统联机运行节能策略

根据卷烟厂空调系统夏季空气露点温度偏高和空调负荷全年变化的特点 ,提出改变冷冻供水温度的控制策略 ,此控制策略有助于改善空调表冷盘管的换热、除湿效果 ,降低冷水机组的全年运行费用。预期每年节省冷水机组的运行费用 2 0 %以上。     

HACCP管理体系在北京奥运餐饮安全管理中的运用

HACCP管理体系是目前国际上广泛使用的一种对食品卫生安全监控的管理制度。HACCP管理体系的适应很广，几乎适合于所有的食品加工、饮料生产等行业。近年来，世界上的许多国家和地区将HACCP管理体系运用于餐饮安全的卫生管理中，收到了非常好的效果。事实证明，餐饮管理引入HACCP管理体系，是确保餐饮安全管理的有效手段之一。 2008年的北京奥林匹克运动会，对于餐饮食品安全的要求将是非常严格的，如何确保奥运会期间所有人员饮食安全，将是摆在我们面前的一项重要而又艰巨的任务。本人认为，将HACCP管理体系运用于北京奥运的餐饮安全管理中将是非常有越要的，其意义也是深远的。     

Monitoring of sensory attributes used in the quality payment system of Trentingrana cheese

Trentingrana is a Protected Designation of Origin (PDO) hard cheese manufactured in the valleys of Trento province (eastern Italian Alps) by several small cooperative dairies linked in a consortium. Nine months after production, wheels are delivered to a shared facility, ripened up to 18 mo, and assessed by a panel of 8 experts for 7 sensory attributes; namely, external aspect, rind thickness, paste color, texture, odor, taste, and aroma. The evaluation takes place every 2 mo on wheels sampled within each dairy. Based on the results of the assessment, dairies receive a price premium or penalty depending on a quality index, which is the weighted sum of the scores attributed to each sampled wheel. Sensory scores and quality index of 652 wheels representing 11 dairies and 10 yr of production were analyzed using a model that included fixed effects of dairy, year, and season of production, and first-order interactions between them. The coefficients of determination ranged from 0.50 (texture) to 0.66 (aroma). All factors significantly affected the studied traits, with the exception of interactions between dairy and season of production for texture and external aspect, and between year and season of production for odor. Dairy was the most important source of variation for visually assessed traits (external aspect, rind thickness, paste color, and texture) and for quality index, whereas year of production was the most important for flavor attributes (odor, taste, and aroma). The latter traits were always highly correlated among them and with the quality index, whereas correlations among visually assessed attributes, between them and flavor attributes, and between them and the quality index were more erratic. The sensory evaluation performed by the panel of experts has proven to be a useful tool to define the quality index and address the payment system of Trentingrana cheese, but it has some limitations in correctly describing the sensory profile of cheese and identifying specific defects and possible remedies.     

Effect of gellan,alone and in combination with high-methoxy pectin,on the structure and stability of doogh,a yogurt-based Iranian drink

Doogh is a traditional Iranian drink prepared by fragmentation and dilution of yogurt, with addition of salt and flavouring. In the present work, we have used viscometry, microscopy, particle-size analysis and measurements of serum separation to explore the effect of very low concentrations of gellan gum (0.01, 0.03 and 0.05 wt %), alone or in combination with 0.25 wt % high-methoxy pectin (HMP), on its structure and stability. HMP is known to prevent association of casein particles in acidic milk drinks by steric stabilisation, forming a protective layer bound electrostatically to the surface of the particles. Doogh incorporating 0.25 wt % HMP alone showed satisfactory stability on storage for ∼10 days at 5 °C, but after 15 days there was obvious separation into a dense sediment and a much clearer upper layer that occupied more than 80% of the total volume, which we attribute to progressive sedimentation of individual sterically-stabilised particles. Samples incorporating gellan (with or without HMP), by contrast, showed rapid development of a clear serum phase, with little further separation at longer times (up to ∼1 month), suggesting expression of fluid by contraction of a gel network (i.e. syneresis rather than sedimentation). Particle size increased dramatically (more than 10-fold) with increasing concentration of gellan, and at the highest concentration studied (0.05 wt %) a continuous network of casein-rich strands was observed by phase-contrast microscopy. The concentration of NaCl used in the doogh samples (0.5 wt % ≈ 85 mM) is known to be sufficient to maintain gellan in its ordered (double-helix) conformation, which has higher charge density than individual molecules of HMP. We suggest that network structure is formed by electrostatic attachment of gellan to fragments of acid-casein gel, thus increasing particle size and inhibiting surface-coverage by HMP, with weaker associations between gellan helices allowing the samples to flow. Observed decrease in serum volume with increasing concentration of gellan is attributed to formation of progressively stronger coupled networks with greater resistance to syneresis. Stabilisation of doogh with 0.05 wt % gellan in combination with 0.25 wt % HMP had no adverse effect on organoleptic acceptability, and reduced serum volume on protracted storage to ∼10% (in comparison with over 80% for the same concentration of HMP alone), suggesting that gellan could be of practical value in extending the shelf-life of doogh (and related acidic milk drinks).