为了降低冷藏陈列柜运行能耗,将自然冷源引入具有储能装置的冷藏陈列柜,对搭建的自然冷源食品冷藏陈列柜系统的5种工作模式(制冷机组单独供冷、制冷机组供冷+蓄冷、蓄冷罐供冷、自然冷源供冷和自然冷源供冷+蓄冷)进行了试验研究.研究结果表明:在5种工作模式下,均能使柜内温度维持在-1～7?℃之间,符合冷藏陈列柜食品冷藏要求.在制冷机组供冷+蓄冷模式下,以2.34?m3/h的乙二醇溶液对蓄冷罐蓄冷12?h后,蓄冷罐能够储存121400?kJ的冷量,该冷量可使柜内温度在9?h内维持在-1～7?℃之间.当室外温度低于-4.5?℃时,可运行自然冷源单独供冷模式.当室外温度小于?-8?℃时,利用自然冷源对陈列柜供冷的同时可以对蓄冷罐蓄冷.运行蓄冷罐单独供冷模式和自然冷源单独供冷模式,能够使系统的能耗分别降低68.45％和55.42％.

In this study, a simulation model of a natural cold source-based refrigerated display cabinet system is established by using the TRNSYS software. First, the air supply temperature of the display cabinet and the cooling temperature of the coolant are selected as variables, and the annual energy consumption is considered as the assessment index to optimize the operating conditions of the natural cold source-based refrigerated display cabinets for food storage. Second, the operating characteristics of the system are analyzed based on optimization and compared with the energy consumption of traditional food refrigerated display cabinets. The results show that the annual energy consumption of the optimal working condition system is the lowest（11 506 kW·h） when the air supply temperature of the display cabinet and the cooling temperature of the coolant is-1.5 ℃ is-3 ℃, respectively. Compared with the traditional food refrigerated display cabinets without a natural cold source, the energy consumption of this system is reduced by 40.8%. In the optimum working conditions, the total operating time of the natural cold source-based cold thermal energy storage cooling mode and the natural cold source-based separate cooling mode is 3 739 h, accounting for 42.7% of the total running time during the entire year; the COP（coefficient of performance） of the system is 3.9, and the COP of the refrigeration unit is 4.1.

为了优化立式敞开式冷藏陈列柜的风幕性能,在食品搁架前端加装翼型结构对风幕进行导流.研究翼型结构对冷藏陈列柜风幕性能的影响.结果发现:在测试环境温度为25℃,相对湿度为60％,柜内温度维持在-1-5 ℃的需求条件下,加装翼型结构后,送、回风平均温度波动范围由0.6--4.4 ℃,10.3-12.0℃变化至1.8-3.0 ℃、6.0-7.4 ℃,热负荷降低19.7％:进一步研究翼型结构加装位置对风幕的气流组织的影响.模拟结果表明:加装翼型结构使风幕的气流分布更加均匀和稳定,热卷吸系数降低17.9％-25％;当翼型结构安装在距搁架前端90 mm处风幕的热卷吸系数达到最低(为0.3),说明翼型结构加装在此处时,风幕效率最高.

This work focuses on the heat transfer and flow characteristics with the different placement of the multi-deck display cabinet and tries to optimize the placement position of refrigerated display cabinet. First, the temperature distribution in a refrigerated display cabinet was experimentally investigated. The result showed that the food temperature in front is 3.6–4.8°C higher than back row of the same layer, and temperature fluctuation of 0.3–0.7°C less than the back row. Then, a three-dimensional numerical model of the display cabinet was established, and the k–ε model is employed to compare and analyze the heat transfer and air curtain characteristics. The results show that the placement methods have great influence on the performance of the display cabinet. The face-to-back placement method can acquire a better food refrigeration performance, and the food temperature of the face-to-back placement method is 0.3–0.5°C lower than that of the face-to-face placement method.

In this study, an airfoil structure was added in front of the display cabinet shelf to optimize the performance of a vertical open-type refrigerated display cabinet. The influence of the airfoil structure on the performance of a vertical open refrigerated display cabinet was studied by testing the performance of the refrigerated display cabinet after addition of the airfoil structure. The test results show that under an ambient temperature of 25 ℃and relative humidity of 60 %, the evaporation temperature of the refrigeration system increased from ?6.3 ℃ to ?4.5 ℃ after installation of the airfoil structure. The average temperature fluctuation of supply and return air varied from 0.6?4.4 ℃, 10.3?12.0 ℃ to 1.8?3.0 ℃ and 6.0?7.4 ℃. The supply air velocity was essentially the same, and the return air velocity decreased by 10.2%–16.9%. The thermal permeability coefficient in the display cases decreased by 46%–48%. The maximum average temperature difference of food in different layers of the cabinet decreased by 31%, and the maximum average temperature difference of food inside and outside decreased by 46.2%. The total heat emission of the showcase decreased from 82.33 kW?h/24 h to 66.49 kW?h/24 h. The total energy consumption of the system decreased from 42.91 kW?h/24 h to 33.61 kW?h/24 h. The results show that the refrigerating system performance, air curtain performance, temperature uniformity, and energy utilization ratio of the open display cabinet can be improved by adding an airfoil structure at the front end of the shelf.

The load of the showcase is a nonlinear and unstable time series data, and the traditional forecasting method is not applicable. Deep learning algorithms are introduced to predict the load of the showcase. Based on the CEEMD–IPSO–LSTM combination algorithm, this paper builds a refrigerated display cabinet load forecasting model. Compared with the forecast results of other models, it finally proves that the CEEMD–IPSO–LSTM model has the highest load forecasting accuracy, and the model’s determination coefficient is 0.9105, which is obviously excellent. Compared with other models, the model constructed in this paper can predict the load of showcases, which can provide a reference for energy saving and consumption reduction of display cabinet.

为了挖掘冷藏陈列柜运行数据的有效信息,实现冷藏陈列柜制冷负荷的预测,针对运行数据存在时间序列性和非线性等特性,提出了基于深度学习的LSTM神经网络模型.将日期信息、蒸发器进出口温度、压力、焓值、流量数据按照时间步长划分为训练集与测试集,模型导入后经过训练证明最优方案:模型网络层数为4、训练次数为200,将预测负荷数据与实际负荷进行比对,发现预测模型绝对百分比误差仅为1.98％,具备较好的预测性能.

在M3工况下对敞开立式食品冷藏陈列柜安装导流格栅前后的冷藏性能进行试验研究,分析了开式食品冷藏陈列柜加装导流格栅前后陈列柜内温度及能耗的变化规律.试验结果表明:在搁架前端加装导流格栅能够显著改善风幕性能,达到节能的效果.在陈列柜搁架安装导流格栅后的后排食品包平均温度都在不同程度上高于安装之前的食品包平均温度.且搁架末端设置空气导流格栅比未设置导流格栅的陈列柜的电能消耗节省约23％.

为实现机械通风冷却塔高效节水消雾,通过对冷却塔水蒸气羽雾机理研究,设计了机械通风冷却塔冷凝收水消雾系统,提出了冷却塔节水消雾新方法;对有限空间型冷却塔(CSCT)和自由空间型冷却塔(FSCT)冷凝收水消雾装置进行了设计,采用间壁式换热器为冷凝装置设计形式,冷凝装置冷热通道采用换热板构建组装;通过实例设计计算,冷凝收水消雾装置节水消雾效益显著.研究结果可为节水消雾型冷却塔开发和在役冷却塔收水消雾技术升级改造提供参考.

以郑州地区某一太阳能热泵系统为对象,,研究了在冬季典型工况下太阳能集热面积、蓄热油箱容积的匹配关系.结果 表明:适当增大蓄热油箱容积或太阳能集热器集热面积都会引起太阳能保证率的增大,同时可有效降低热泵供热量减少系统能耗.在经济性考虑下最优解为太阳能集热面积300 m2和蓄热油箱10 m3的方案.同时太阳能集热器集热面积和蓄热油箱容积的增大对太阳能供能比例的提升作用呈现出先增大后逐渐放缓.

微通道平行流换热器以其造价低、重量轻、结构紧凑、换热效果好等诸多优点,在化学工程、石油、制冷等领域均有广阔的应用前景,但是制冷剂流量分配不均匀等问题严重影响了平行流换热器的性能.通过在平行流换热器的基础上设计了一种新的分流板结构,以水为模拟工质,运用数值模拟比较增加分流板前后的各管道流量和总流量分布不均匀度.结果 表明:增加分流板以后,各通道流量分布的均匀性能提高4％-20％,速度越大改善越明显,改善后其总流量分配不均匀度比改善前降低了36％～ 78％.

对完全利用自然冷源为冷藏陈列柜供冷进行试验研究,在室内温度为20℃,相对湿度为50％的标准工况下,分析自然冷源温度(-4～2℃)、相对湿度(45％～90％)、送风风速(0.8～1.2 m/s)对柜内温度的影响.结果表明:柜内各层温度随自然冷源温度的升高而升高,内侧受自然冷源温度影响大于外侧;各层食品包温度均随相对湿度的增加而下降,但是陈列柜不同位置温度受相对湿度影响程度不同;陈列柜内各层温度随送风风速的增加呈逐渐下降的趋势,外侧温度受送风风速影响程度较大.

通过试验方法对郑州地区文洛型玻璃温室在湿帘-风机机械通风和自然通风两种方式下室内热工参数的变化特性进行了研究.结果表明,在机械通风条件下,温室内沿垂直方向存在明显的温度梯度,水平面上靠近湿帘侧的温度低于靠近风机侧的温度;采用机械通风的方式可将温室内距地面高度1.2 m以下空气温度比室外降低3.5～9.0℃,垂直方向温度梯度较大,可考虑加入轴流风机加强温室内空气流动;而采用自然通风时,温室距地面高度1.2 m以下的平均温度比外界气温高3.8℃,在外界温度较低时自然通风的降温效果较好,适用于夏季初期.

为弥补太阳能间歇性的缺点,设计了管壳式蓄热装置并建立了一个三维的、非稳态的、液态石蜡包含自然对流的相变蓄热装置模型,在该模型中取一个蓄热单元进行模拟研究.蓄热单元为圆柱体,内部放置石蜡,中心位置为传热管,热水通过传热管和传热管上的翅片对石蜡进行加热.对蓄热单元的蓄热过程进行了三维数值模拟,分别分析比较了有无自然对流条件,不同蓄热单元放置,以及增加内外翅片情况下蓄热单元的蓄放热性能,研究结果可为蓄能装置及集成系统的开发提供理论依据.

以典型的多层搁架冷藏陈列柜为研究对象,在室内温度为25℃且相对湿度为60％的条件下,针对搁架长度和送风速度对冷藏陈列柜风幕效率的影响进行数值模拟,并进行试验验证.结果表明:在送风速度一定的条件下,搁架长度对冷藏陈列柜放置的周围环境温度影响较大,对周围空间区域的气流组织影响很小,φ=4°时冷藏陈列柜风幕能够更好地阻挡外部热空气的入侵;当进口风速为2 m/s且φ=4°时,风幕效率值最小.

通过试验研究的方法,将自然冷源引入冷藏陈列柜,在完全利用室外冷源对陈列柜柜内进行供冷的运行模式下,保持风幕送风速度为1.1 m/s,室外送风温、湿度分别为1.0℃、60%,室内湿度为60%不变,调节室内不同的温度,观察柜内食品包温度变化分布,研究陈列柜食品包冷藏特性.实验结果表明:与利用制冷系统供冷的传统陈列柜相比,自然冷源供冷使柜内温度分布均匀性得到很大提升,自然冷源陈列柜1~5层同侧食品包温差不超过1.5℃,但是每层内侧和外侧食品包温差在2.5~3.0℃.在此送风条件下,保证室内温度在22.0℃以下可以满足柜内食品贮藏温度0.0~7.0℃的要求.风幕参数变化规律:随着食品包前端距离的增加相对湿度呈现先增大后减小,最后稳定于和室内湿度相等的趋势.风速和温度呈逐渐减小的趋势,且变化速率不断减小.

运用数值模拟的方法,通过改变入口Re数分析U型和Z型两种不同进出口结构的梯形微通道换热器.研究表明:随着入口速度的增加,两种结构的总流量分配不均匀度变大,Z型结构梯形微通道换热器的不均匀度增加了约89.7％,U型结构梯形微通道换热器不均匀度增加了约87.7％,U型结构梯形微通道整体不均匀性比Z型结构梯形微通道不均匀性增加了12％-31％.入口速度较低时,两种结构梯形微通道的进出口压降比较接近,随着入口速度的增加,U型结构的进出口压降逐渐大于Z型.

Using water as the working fluid,the flowing situation of fluid in the micro parallel flow channel under different export-import structure and Re was studied by the experimental method,using high speed photography system,the flow of fluid in the Z-type and U type micro channels was obtained,the flow rate of each channel fluid was extracted by plus Image-pro software.The results show that under the test Re,the uniformity of flow distribution of Z-type and U-type heat exchanger with the decrease of Re is better,the overall flow distribution uniformity of the Z-type heat exchanger is increased by 80.4％,the overall flow distribution uniformity of the Utype heat exchanger is increased by 64.3 ％;the export-import structure has great influence on the flow distribution and pressure drop,compared with U-type,the overall uniformity of Z-type is increased by about 2％-44％,the pressure drop of Z-type is decreased by about 1.2％-19.9％,so the Z-type has better comprehensive performance.

Through the experimental study , the natural cool source is introduced into the refrigerated display cabinet .Under the case of air curtain velocity being 1.2 m/s, the outdoor humidity being 10% RH, the indoor temperature being 25 ℃, humidity being 60%RH, the variation law of the food package temperature under differ-ent temperature of natural cool source is studied .The experimental results show that the display cabinet of natural cool source can ensure the storage temperature of food .The temperature changes of shelf food package in each layer tend to be consistent , with the increase of the temperature of natural cool source .When the temperature of natural cool source is below 0 ℃, the natural cool source and return air combined cycle;when the temperature of natural cool source is in the range of 0~3 ℃, completely using outdoor cool source for cooling;when the temperature of natural cool source is above 3 ℃, making completely use of the display cabinet cooling system .