水流量对热泵热水器性能影响的实验研究

针对空气源热泵热水器运行工况多变,制热效率不稳定的特点,设计了循环加热式热泵热水器实验装置,系统由制冷剂循环和水循环两部分构成,重点研究了水流量对系统性能的影响。实验结果表明:逐时能效比随水温的升高而下降,加热前期水流量越大能效比越低,加热后期刚好相反;水流量越小系统越容易吸气带液,吸气带液会使制热量降低,能效比下降速率增大,导致系统性能变差;吸气带液时,制冷剂流量减小,换热系数增大,与换热系数相比制冷剂流量对制热量的影响更大。该结果为系统实际运行和进一步研究提供参考。     

CO_2跨临界循环水源热泵系统的试验研究

为研究CO2在热泵领域的应用,设计并搭建了CO2跨临界循环水源热泵系统试验台,研究系统在不同工况下运行的性能参数.试验结果表明:在水源温度为30℃,初始水温度为25℃,蒸发温度为10℃,终止水温度为60℃和65℃,蒸发器侧的水热源流量为0.6 m3/h条件下,系统COPH随着高压侧压力的升高,呈现出先升高后降低的趋势,最大COPH为4.4,与其相对应的高压侧压力为最优高压侧压力.     

涤纶针织鞋材超临界CO2无水染色性能

为解决传统染色高污染、高能耗问题，实现鞋材无水清洁化染色，研究了涤纶针织鞋材在超临界CO₂体系中的染色性能，分析了染色温度、压力、时间以及CO₂流量对针织鞋材染色效果的影响。在实验条件范围内，染色鞋材的K/S值随温度、压力的升高而增大，并最终趋于稳定，获得最佳染色工艺条件为：染色温度120℃,染色压力24 MPa,染色时间60 min, CO₂流量400 kg/h。涤纶鞋材的耐摩擦和耐皂洗色牢度均达到4级以上。并进一步探究了染色温度、压力对针织鞋材力学性能的影响。结果显示：鞋材的抗弯刚度、最大抗弯力与断裂强力、顶破强力随温度、压力的上升而增大；断裂伸长率随温度、压力的上升而降低；收缩率随温度、压力的上升而增大；鞋材的表面摩擦因数无明显变化；其中温度对鞋材力学性能的影响大于压力的影响。     

循环加热式空气源热泵热水器运行性能的试验研究

以套管式换热器作为热回收元件对循环加热式空气源热泵热水器的运行性能进行试验研究,指出:水箱水温从15℃升高到55℃时,系统参数如吸、排气压力,进、出水温度等随着水箱水温的变化而升高,同时系统的能耗也增大,而系统性能系数有所降低,在3.69左右,但与传统热水器相比系统还是节能的,是可行的.     

清酒罐CO2平衡系统的运用

本文主要针对清酒罐CO₂平衡系统的使用进行交流与探讨。1 CO₂使用分析CO₂在啤酒生产过程中用途很广,主要用于酒液容器备压、脱氧水制备等。啤酒中CO₂含量和罐压、温度的关系为:CO₂（%,m/m）=0.298+4p-0.008t,其中:p—罐压（表压MPa）;t—啤酒温度（℃）当罐体压力达到0.05MPa、酒液温度为-1℃时,酒液中的CO₂含量达到0.50%（m/m）,因此发     

跨临界CO2热泵热水器的实验研究

为了提高热泵热水器的效率,搭建了CO2热泵热水器实验台.实验结果表明:在冷却水出水温度为65 ℃时,CO2热泵热水器的COP随着蒸发温度的升高而升高;在某一蒸发温度下,气体冷却器放热量随着高压压力的升高先升高而后降低,系统的COP存在一个最优值.     

跨临界CO_2热泵热水器的实验研究

为了提高热泵热水器的效率,搭建了CO2热泵热水器实验台.实验结果表明:在冷却水出水温度为65℃时,CO2热泵热水器的COP随着蒸发温度的升高而升高;在某一蒸发温度下,气体冷却器放热量随着高压压力的升高先升高而后降低,系统的COP存在一个最优值.     

分散红11在超临界二氧化碳中的溶解度及其模型拟合

为实现超临界二氧化碳(CO₂)染色的工业化应用,采用自主研发的高压超临界流体实验装置,在温度为353.15~393.15 K、压力为16~24 MPa条件下,利用动态法测量了分散红11(1,4-二氨基-2-甲氧基蒽醌)在超临界二氧化碳中的溶解度,并采用Chrastil经验模型和MST方程对实验结果进行拟合,探讨影响分散染料在超临界CO₂中溶解度的因素。结果表明:压力越高,二氧化碳密度越大,分散红11在超临界CO₂中的溶解度越高;随温度升高,分散红11的溶解度先增加后降低;分散红11的最优溶解度工艺条件为温度383.15 K,压力24 MPa;Chrastil经验模型关联水平在0.90以上,MST方程关联水平为0.55,Chrastil经验模型关联结果优于MST方程。     

分散紫27与分散蓝72在超临界CO2中溶解度的测定

在温度343.15~383.15 K、压力14~22 MPa条件下,采用动态法测定分散紫27、分散蓝72在超临界CO₂中的溶解度。并采用Chrastil半经验模型和AdMST半经验方程对实验结果进行关联,探讨影响分散染料在超临界CO2中溶解度的因素。结果表明:分散紫27在超临界CO₂中的溶解度为2.69×10^-6~7.35×10^-6 mol/mol,压力越高,CO₂密度越大,分散紫27在超临界CO₂中的溶解度越高;随着温度的升高,分散紫27的溶解度先升高后降低;分散蓝72在超临界CO₂中的溶解度为7.17×10^-6~13.38×10^-6 mol/mol,且随着温度的升高而升高,随着压力的升高而升高。     

再生聚酯纱线的超临界CO2萃取除油工艺

再生聚酯在纺纱时需加入纺丝油剂,油剂会影响后续染色过程。为减少油剂对后续染色过程的影响,采用超临界CO₂流体萃取法,研究了再生聚酯纱线在超临界体系下的除油效果,选取除油温度、压力、时间、CO₂流量作为研究因素,利用响应面法对工艺条件进行优化,采用扫描电镜和红外光谱分析进一步对除油后纱线性能进行探究。结果表明：最佳工艺条件为除油温度64℃,除油压力21 MPa,除油时间60 min, CO₂流量415 kg/h,在此条件下再生聚酯纱的除油率可达到78%,超临界CO₂除油后的纱线表面油剂有一定减少,纱线物理结构未受到影响。     

Impact of intake water temperatures on reticular temperatures of lactating dairy cows

Automatic temperature recording may allow early detection of disease, estrus, heat stress, and the onset of calving. The phase IV Cattle Temperature Monitoring System (MaGiiX Inc., Post Falls, ID) utilizes a passive bolus equipped with a temperature sensor, a stationary panel reader to query the bolus, and software to collect, analyze, and display data. One potential limitation to collection of reticular temperatures is the effect of water temperature and consumption on recorded temperatures. Two replicated 3 × 3 Latin square experiments were conducted at the Purdue Dairy Research and Education Center to assess the impact of water intake on reticular temperatures using the Cattle Temperature Monitoring System. Nine high-producing, mid-lactation, second-parity cows with low somatic cell counts were selected. Before administering a water treatment, access to feed and water was restricted for at least 2 h. Baseline reticular temperatures were established from measurements before water intake. In experiment 1, treatments were 25.2 kg of hot water (34.3°C ± 1.0), warm water (18.2°C ± 0.4), or cold water (7.6°C ± 0.4). In experiment 2, treatments were 18.9 kg of body-temperature water (38.9°C ± 0.2), cold water (5.1°C ± 0.4), or control (no water). Following water intake, reticular temperatures were collected for 3 h. In experiment 1, an initial dramatic decrease in reticular temperature was observed followed by a gradual increase toward baseline. Least squares means for maximum drop in temperature were 8.5 ± 0.5, 6.9 ± 0.5, and 2.2 ± 0.5°C for cold, warm, and hot water treatments, respectively. Yet at 3 h, reticular temperatures did not return to the baseline. In experiment 2, control cows remained within the baseline confidence interval through the observation period, and cows receiving body temperature water experienced an initial decrease in temperature (0.4 ± 0.2°C) with a return to within the baseline confidence interval within 15 min. Cows receiving cold water did not return to within the baseline confidence interval after a large decrease of 9.2 ± 0.2°C during the 3-h observational period. Moreover, a regression analysis of continued ascent in temperatures predicted that temperatures would return to baseline within 3.5 h. These results demonstrate that, when cows consume large quantities of cold water, the effect of water intake is sizable and sustained. The value of reticular temperatures for daily monitoring in a production setting hinges largely on the implications of this impact.     

Water status and quality improvement in high-CO2 treated table grapes

Unfreezable water (UFW) content in berry tissues (pulp, skin, seed) and rachis of table grape clusters stored at 0 °C has been studied using differential scanning calorimetry. The effect of short exposure to high CO₂ (20% CO₂ for 3 days) and the transfer to air were also studied. Water status of pulp tissues was related to the thawing behaviour and the structural characteristics, using low-temperature scanning electron microscopy (LT-SEM). The UFW content in all tissues increased rapidly in response to high CO₂ while it remained stable or decreased in untreated clusters. The strong potential of this beneficial gaseous treatment for increasing the UFW content was also evident after transfer to air. The metabolic adjustment caused by exposure to high CO₂, which reduced the amount of water available to be frozen, improved stored fruit quality, thus minimising structural damage and reducing water leakage associated with the freezing–thawing process.     

Effect of ambient temperature and sodium bicarbonate supplementation on water and electrolyte balances in dry and lactating Holstein cows

The aim of this study was to quantify the effect of the interaction between 2 constant ambient temperatures [thermoneutrality (TN; 15°C) and high temperature (HT; 28°C)] and 2 levels of Na bicarbonate supplementation [calculated to provide diet Na contents of 0.20%DM (Na−) and 0.50%DM (Na+)] on water partitioning in dairy cows. Treatments were compared on 4 dry and 4 mid-lactation Holstein cows according to 2 Latin squares (1 for each physiological stage) over the course of 4 periods of 15 d. Diets consisted of a total mixed ration based on maize silage. Dry cows were restricted to their protein and energy requirements, whereas lactating cows were fed ad libitum. The daily average temperature-humidity index was 59.4 for TN and 73.2 for HT. Lactating and dry cows had higher vaginal temperatures at HT than at TN, but the increase was more pronounced in lactating cows (+1.05 vs. +0.12°C for vaginal temperature, respectively). Dry matter intake (DMI) of lactating cows decreased by 2.3 kg/d at HT. Free water intake (FWI) and estimated volume of water lost to evaporation increased at HT in both lactating and dry cows; no interactions were observed between temperature and physiological stage. When expressed as a proportion of DMI, the increase in evaporation that occurred with increasing temperature was completely compensated for by an increase in FWI for both physiological stages. The urinary water excretion increased slightly at HT in lactating cows but not in dry cows, which may be related to the low chloride content of the offered diet. High Na supplementation increased DMI slightly in lactating cows, but milk yield was not affected. Sodium supplementation did not limit the decrease in DMI observed in lactating cows at HT; this observation is likely due to the high diet electrolyte balance of the offered diets. Sodium supplementation increased FWI in lactating cows and urinary flow in both physiological states. The interaction between ambient temperature and Na supplementation did not affect either water intake or water evaporation. This study demonstrates that the development of predictive models for water intake that include environmental variables could be based on mechanistic models of evaporation.     

新型精密收缩温度仪的研究

通过对皮革传统收缩温度仪的分析 ,提出了以水蒸气作为加热介质的设想 ,设计出了全自动新型精密收缩温度仪。试验表明 :用水蒸气代替水和甘油作加热介质 ,所测得的皮革试样的收缩温度更准确     

循环流化床锅炉过热器安全运行

锅炉过热器的安全运行,是保障盐业企业正常稳定运行的前提,本文从锅炉本体、煤质、水质、管理等方面对影响过热器安全运行的因素进行了分析。提出了改进措施和努力方向。     

影响打浆度测定准确性的因素

初步探索影响测浆准确性的几个因素,包括水温、测浆浓度、仪器校准等,并介绍了一种简单易行的浓度检测方法。     

培养箱内部热流场的数值模拟及开关门过程的影响

基于CFD软件Fluent,对某种新型二氧化碳培养箱及其工艺参数,建立气体流动、传热的数学模型。对其内部的流动、传热进行非稳态数值模拟,并对开关门过程的影响进行分析。结果表明:培养箱打开外门5s内,外界空气对箱内温度影响不大;打开玻璃门25s内,外界空气对箱内温度影响区域顺序分别为从门框附近到箱体内部,从箱内下部到上部,从开门位置的左壁面到已开启的外门一侧的右壁面附近区域;关闭外门后,箱内靠近背壁面以及右壁面附近区域温度的恢复效果较好,靠近门附近区域的温度较难恢复。     

加水温度对莜麦面团水分分布状态和质构特性的影响

烫熟是莜麦传统特色食品制作的重要步骤,对产品品质影响显著。利用低场核磁共振技术得到莜麦面团的水分分布状态,采用食品物性仪测得莜麦面团的质构特性参数,研究了加水温度对莜麦面团水分分布状态和质构特性的影响。结果表明：当加水温度由70℃升高至90℃时,莜麦面团中弱结合水和自由水与底物的结合程度增加,弱结合水向自由水方向迁移并使面团中水分的主要存在形式发生改变,当加水温度由70℃升高到75℃时,莜麦面团中水分的主要存在形式即由弱结合水变为自由水;加水温度升高,对莜麦面团的弹性影响不显著,能显著增加莜麦面团的硬度、胶着性和咀嚼度,显著减小黏聚性,使黏着性先增加后减小,且水温为75℃时,莜麦面团的黏着性最强。     

Methods for measuring water activity (aw) of foods and its applications to moisture sorption isotherm studies

Moisture sorption isotherm is commonly determined by saturated salt slurry method, which has defects of long time cost, cumbersome labor, and microbial deterioration of samples. Thus, a novel method, a_w measurement (AWM) method, has been developed to overcome these drawbacks. Fundamentals and applications of this fast method have been introduced with respects to its typical operational steps, a variety of equipment set-ups and applied samples. The resultant rapidness and reliability have been evaluated by comparing with conventional methods. This review also discussed factors impairing measurement precision and accuracy, including inappropriate choice of predryingwetting techniques and unachieved moisture uniformity in samples due to inadequate time. This analysis and corresponding suggestions can facilitate improved AWM method with more satisfying accuracy and time cost.     

气象、样品属性等因素与花生油中黄曲霉毒素B1污染水平关联性分析

目的 以2017—2018年广东省市售花生油中黄曲霉毒素B₁（AFB₁）的污染状况为例,分析特定因素对AFB₁污染的影响。方法 采集2017—2018年广东省21个地市637份花生油样品,记录其样品标签属性,并根据GB 5009.22—2016《食品中黄曲霉毒素B族和G族的测定》中的高效液相色谱-柱后衍生法测定样品中AFB₁含量。结合第五代欧洲中期天气预报中心全球气候大气再分析数据库（ERA5）获得的样品产地气象数据计算样品生产前1个月的平均数据,并分析其与AFB₁含量关联性。结果 广东省2017—2018年市售花生油中AFB₁总检出率为65.3%,超标率为24.6%。其中,定型包装花生油样品无超标,而散装花生油样品有较高的超标率,且AFB₁含量中位数显著高于定型包装样品。在多个气候因素中“花生油生产前1个月的平均气温水平”与散装包装样品AFB₁的超标率和含量有较强的关联,其中生产前平均气温超过25 ℃的散装包装样品AFB₁含量中位数约为气温低于22 ℃样品的3.5倍。然而其他气候因素并未展现出与AFB₁含量的相关性。结论 2017—2018年广东地区散装花生油样品AFB₁具有较高的超标率,而花生油生产前1个月平均气温是影响其AFB₁含量的重要因素。建议对广东省散装花生油的生产环境、生产方式进行重点关注并提高花生油质量,以减少居民AFB₁等危险因素的暴露风险。