立式水冷器冷却水均布技术研究

冷冻水冷器各传热管冷却水量分布不均匀使其冷却效率普遍很低。本文简要评述了目前常用分布结构所存在的问题及其原因 ,提出了池式均布筛板理论 ,并且进行了模拟试验和结构参数的优化研究。试验结果表明 ,均布技术的关键参数是筛板上的积水池深度 ,达到 12 5 mm以上时冷却水分布的整体均匀度可以达到 85 %以上 ,可以满意地解决现在普遍存在的不均布问题。这种均布技术结构简单 ,设计方法也十分简便 ,可以很方便的推广应用。     

水冷器流态化自动清洗防垢与节水节能技术研究

轻工部门冷冻系统中使用的立式水冷器较多,其流速很低,水垢比较严重,效率较差。为解决这一问题,研究了高可靠性内循环流态化水冷器结构,底室采用泡罩板加大孔均布板取代筛孔容易堵塞的筛板,水冷管出口安装挡粒调匀罩。通过优化试验,结果表明:采用直径120 mm的泡罩、流态化粒子层厚度150 mm以上、孔径8 mm的均布板、高度30 mm的挡粒调匀罩,能够有效地防止出口室跑失流态化清洗粒子,各水冷管内的流速分布的均匀性较好,可以满足稳定运行的可靠性要求。在一般水冷器流速范围内,冷却强化幅度60%以上,在线自动清洗效果好,节水节能的综合效益较高。     

大型降膜蒸发器液体分布器的设计

为使大型降膜蒸发器的液体分布器能够稳定均匀地布膜，必须对其进行合理的设计。通过对分布器的结构、分布盘筛板上的布孔方式、主要结构参数和工艺参数等方面进行分析探讨，确保了分布器的良好性能。实验和应用证明：据此设计的盘式分布器能满足均匀布膜的要求，适于大型降膜蒸发器。     

轴承旋流强化的管内污垢自动清洗扭带技术

冷饮与速冻工业的水冷器大多为列管式结构。实际运行的管内冷却水流速一般为0．5～1．0m／s，易结垢，效率低。通过强化理论分析和结构设计的优化试验，研究成功了旋流轴承强化塑料扭带自动清洗技术，能够使现有光滑扭带的清洗力矩成倍增加；可以使水冷管长度为2m、4m、6m的水冷器对管内冷却水的流速要求由原先的1m／s以上，分别下降至0．4m／s、0．5m／s、0．6m／s，从而使多数水冷器可以直接应用管内污垢自转塑料扭带自动清洗技术，并且流体的阻力不大，结构简单，便于推广应用。     

高效节水节能的内循环流态化水冷器技术

内循环流态化换热器的应用效益相当高，但是还不够完善，较长时期运行后可能发生流态化底室筛板部分筛孔堵塞和出口室沙子跑失的问题。中重点研讨了采用泡罩板取代筛板解决堵塞问题后出现的均匀性问题，多方案优化的结果是采用较大直径的泡罩，并且加装一块大孔均布板，以满足稳定运行的要求。研制成功的传热管管口档罩，不仅具有防止粒子跑失的功能，而且还具有一定的流速调匀作用和防止低流速管创新粒子倒流的稳定功能。     

机收油菜籽组合清理机设计与试验研究

刚收割的油菜籽中夹带较多碎禾叶、禾秆、荚角等纤维性杂质,进入烘干机之前必须进行清理。针对国内外对机收油菜籽清理技术研究很少和现有油菜籽清理设备不适合处理机收油菜籽的现状,设计了油菜籽组合清理机。采用生产试验和现场检测的方法,分析处理量与油菜籽水分、设备吸风量、筛孔尺寸及分布、筛板倾角及分布、振动频率等参数之间的联系与相互作用。试验表明,当油菜籽含水率高于16%时,组合清理机的筛孔尺寸按上层40×40、中层20×20、下层10×10分布,筛板倾角按上层21°、中层17°、下层13°布置,并且穿过筛孔的实际风速为油菜籽悬浮速度的1.1~1.2倍时,处理量较大,清理效果较好。     

冷冻机立式水冷器污垢的塑料螺旋齿管自动清洗技术研究

冷冻机组立式水冷器的水垢损失每年高达十多亿元。依据其特低流速的特点，研究成功具有在线、连续自动清洗功能的塑料螺旋齿管技术。其原理是由冷凝管与螺旋齿管形成螺旋流道，使冷却水作快速螺旋线流动，其反作用给螺旋齿管形成较强的自转力矩。通过理论分析和多种结构参数的试验研究表明：污垢清洗能力强；自转力矩与冷却水流量二次方正比，较大的内管直径、较小的螺旋角有利于力矩强化，其中力矩最优化的螺旋齿管的力矩强化能达到塑料扭带的241％，可以在0．4m／s以上的流速下可靠应用；传热系数平均提高50％；制造简单。虽然螺旋齿管的阻力大，但是立式水冷器的落差很大。位能充裕，因此，具有很好的工程应用价值．     

筛板塔塔盘排布软件

在筛板塔塔盘设计原理和研究方法基础上,利用结构化设计方法及程序模块化原理,以Visual Bade 6.0为平台,实现了筛板塔塔盘结构尺寸及塔盘排布的快速设计,能更好地实现塔盘结构和筛孔排布的最优化。软件界面友好,操作方便,参数可调,排布结果可复制可保存。     

新型压力筛的结构

从新型压力筛的筛板结构、旋翼结构、筛板的加工方法等方面论述了压力筛筛选技术近期的发展     

筛除斑点尘埃的新型缝筛

筛浆机与筛板研究设计的进展,开拓了筛选亚硫酸盐浆筛板选择的新前景。近转子侧的筛板表面设计成沟槽形(contour-groo-ving),以便能采用较小的孔缝筛板。这种沟槽面筛板与新型筛浆机结合一体,使缝型筛板具有实用价值,能高效率地筛除亚硫酸盐浆中的斑点、尘埃。本文考证采用沟槽面筛板去除亚硫酸盐浆料中的渣团、浆块及斑点、尘埃的情况,并分析了最佳筛选性能时的筛孔大小、筛缝尺寸以及筛板的沟槽面效果。本文所引用的数据是来自几家纸厂与研究部门合作试验的结果。经过大量试验,选定一种称为Turbo筛板进行各项测试,其筛选效果甚佳。Turbo筛板形状如图1所示。测试的筛孔孔径为     

降膜蒸发器筛板式液体分布装置的实验研究

介绍了适用于大型水平管降膜蒸发器的筛板式液体分布装置。以不同浓度、不同粘度、不同温度的水溶液进行了模拟实验。通过分析实验结果,找出了影响液体分布的因素并分析了其影响,给出了在一定操作条件下适合于该分布器的流量范围。     

新型饮用水桶内洗机的设计与研制

随着桶装饮用水屡陷质量危机,据可靠分析,在一定程度上是由于桶装饮用水空桶重复使用造成的。因此在新的形势下,设计并开发一种新型桶装饮用水空桶内洗机势在必行。本文介绍的设备采用了最新工艺流程,即采用处于国内领先水平的工艺方案(6.5~7MPa高压全方位、360°无死角冲洗),不但提高了桶装饮用水卫生等级,而且保证人们饮水健康问题。系统地介绍了该设备的整体方案、主要部件结构设计和控制系统。     

基于高温流化技术改良红小豆的蒸煮品质

以红小豆为原料,采用高温流化技术（流化温度215 ℃、流化处理时间55 s、进料速率62 kg/h）对其进行处理,通过分析红小豆籽粒结构、淀粉结构、糊化特性以及水分吸收、迁移和分布情况,探究高温流化技术改良红小豆蒸煮品质的机理。结果表明,红小豆经过高温流化处理后,籽粒致密结构变得疏松、子叶相邻细胞间毛细孔直径增大、部分淀粉颗粒结构破损。在98 ℃近沸水中蒸煮时,原料红小豆蒸煮60 min时的糊化度与高温流化红小豆蒸煮30 min时的糊化度相当;经过高温流化处理之后,红小豆的糊化黏度更低,回生趋势更小;蒸煮60 min时,高温流化红小豆吸水率为90.06%,比原料红小豆提高34.84%,吸水性能明显改善;高温流化红小豆颗粒内部的水分迁移速率明显加快且分布更均匀;高温流化红小豆煮饭的感官评分更高。综上,高温流化改良红小豆蒸煮品质的途径主要是通过拓宽籽粒水分进入的通道、破坏吸水屏障来提高吸水性能,从而使淀粉吸水更充分、糊化更彻底,同时也改善了其煮饭的口感风味。     

接触脱水膜干燥对南美白对虾干复水特性的影响

接触脱水膜（contact dehydrating sheet,CDS）是一种适用于鱼肉等富含蛋白质食品干燥的新型冷脱水技术。为研究低温脱水对南美白对虾干复水特性的改善作用及其内在原因,本实验研究了CDS脱水至不同水分质量分数虾干的蛋白质结构变化及复水过程中复原率、持水力和水分状态的分布情况,并和热风干燥（hot air drying,HAD）的虾干进行比较。结果表明：采用CDS脱水法制备的不同水分质量分数（60%、45%、30%,以湿基计）虾干复原率、持水力均高于相对应的HAD脱水虾干组,其中水分质量分数为30%时,CDS脱水虾干的复原率、持水力分别为85.22%、69.17%,明显高于HAD脱水虾干（62.55%、65.73%）。低场核磁共振分析表明CDS脱水处理的水分质量分数为30%的虾干复水后虾仁的结合水、不易流动水、自由水比例均比HAD处理组更接近鲜虾。表面疏水性和蛋白质结构分析表明CDS脱水虾干蛋白的表面疏水性变化程度比HAD脱水低,蛋白质二级结构变化比HAD脱水虾干小。因此,CDS脱水法能维持蛋白质结构的完整性,复水后的虾干有更好的复原率、持水力,使产品品质更接近鲜虾,可以作为对虾及其他高值水产品的脱水干燥新途径。     

基于PIV技术的水中气泡的拍摄与用光技巧

水中气泡的拍摄和用光技巧是流体可视化PIV（particle image vdocimetry）技术中一个较难的问题．用自制装置，分别以自然光、弱激光（3mW，He-Ne 632．8nm）和连续脉冲固体强激光（200mw，DPSS 532nm）为光源，用凤凰303K胶片相机，像素420万的CASIOEX-Z40 OCD相机和像素600万的Nikon D100 CCD相机拍摄了水中气泡，通过计算合理控制了水中气泡的景深．用激光扩束方法实现了均匀片光、对称式布光并得出一系列边缘较为清晰的水中气泡照片．所拍摄的水中气泡图片为PIV提供了技术支撑．     

Spatial distribution of lipids modulated by phase separation in emulsified films and the effects on structure-function relationships

The aim of this work was to develop a novel strategy to modulate the spatial distribution of paraffin in emulsified films via tuning phase separation behaviors among zein/gelatin (ZG) matrix, and to elucidate their structure-function relationships. Three phase separation behaviors within ZG matrix, namely, the zein-dominated, gelatin-dominated and ZG-macro phase separation, were developed. When the ZG matrix was tuned to ZG-macro or gelatin-dominated phase separation, the successive or partial bilayer films can be developed due to the spatial distribution of paraffin as the floating layer. While, when zein-dominated phase separation was created, paraffin uniformly distributed as dispersed phase, forming films with monolayer structure. Surface distribution of paraffin, detected by AFM, revealed that distinct interactions between paraffin and zein or gelatin drove the distribution pattern. The bilayer structure more effectively enhanced water barrier properties of films and performed preferable mechanical properties but at the expense of optical properties, whereas the release property of oregano essential oil and tea polyphenol was dominated by the chemistry nature of film matrixes rather than the spatial distribution. This study adds new knowledges to the rational design of emulsified films by tuning the spatial distribution of lipids.     

Characterization of water distribution in xanthan-curdlan hydrogel complex using magnetic resonance imaging, nuclear magnetic resonance relaxometry, rheology, and scanning electron microscopy

Abstract: Xanthan‐curdlan hydrogel complex (XCHC) has been shown capable of retaining moisture up to 5 freeze‐thaw cycles (FTCs); however, moisture distribution in the complex in relation to the hydrogel composition and structure remains uncharacterized. In the present study, magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) relaxometry, rheology, and scanning electron microscopy (SEM) were used to examine the effect of water distribution and interaction with 2.0% aqueous solutions of xanthan, curdlan, and XCHC consisting of equal amounts of both polysaccharides. A gel structure with an indication of syneresis was clearly seen in the MR image of curdlan alone, whereas the distribution of protons throughout xanthan and XCHC samples remained homogeneous and showed no detectable syneresis. The three‐dimensional network, indicated by frequency sweeps, of curdlan was responsible for curdlan's gel structure. The frequency sweep and slope of the storage modulus (G′) of XCHC was significantly closer to curdlan with higher elasticity and less dependency upon angular frequency than xanthan alone. The reduction in XCHC dynamic moduli (G′ and G″) compared to curdlan could be attributed to the formation of wavy layers instead of a fully cured three‐dimensional structure. Addition of xanthan to curdlan restricted XCHC spin–spin relaxation time (T₂) to intermediate and slower exchange regimes, namely approximately 110 and 342 ms, respectively, promoting the polymer's interaction with water while inhibiting interpolymer interactions found in curdlan. A 3rd proton pool with the slowest T₂ seen in curdlan was not found in XCHC, correlating to the absence of syneresis. Practical Application: The combination of texture measurements and discrete noninvasive techniques was found capable of providing insightful understanding of water distribution in a gel system. These techniques may be applied to other hydrogel complexes. The XCHC system investigated has the potential to enhance freeze‐thaw stability in frozen food products by minimizing syneresis due to undesirable temperature fluctuations during distribution and consumer application.     

Changes in liquid‐holding capacity,water distribution and microstructure during chill storage of smoked salmon

BACKGROUND: During recent years, increases in liquid loss and soft texture in cold smoked salmon have been reported, possibly due to increased lipid content and a change in muscle structure. These problems can lead to downgrading of the product. This study aimed to investigate the influence of raw material composition and chill storage on quality parameters of cold smoked salmon. RESULTS: Initial smoked fish had a higher liquid‐holding capacity (LHC) than samples stored for 20 days. Large fish lost more liquid than small fish. The difference in LHC was consistent with a change in water distribution, which could indicate denaturation of muscle protein. Studies of the microstructure showed the influence of both processing and chill storage. An indication of lipid released from the cells was seen after 20 days of chill storage, which could be related to the reduced LHC at that time. CONCLUSION: Both raw material composition and chill storage affected the quality parameters of smoked salmon. This study has improved knowledge about the relationships between muscle structure, liquid‐holding properties and water distribution in smoked salmon. Copyright © 2007 Society of Chemical Industry