温室冷却除湿用翅片管换热器空气侧的性能

为探究温室环境对冷却除湿系统中亲水翅片管换热器空气侧性能的影响机理,在风洞营造的温室环境下(温湿度分别为285～308 K和60%～90%),对带有厚度为0.8 μm亲水涂层的铝翅片管换热器进行了空气侧性能试验,与无亲水涂层翅片管换热器空气侧的性能对比;分析了进口条件对翅片管换热器热质传递及阻力特性的影响,并对现有无亲水涂层翅片的性能预测关联式进行了修正,确保修正后的关联式适用于温室及相似环境下带亲水涂层的翅片管换热器。试验结果表明,带亲水涂层翅片的传热因子、传质因子及摩擦因子均小于无亲水涂层翅片;带亲水涂层翅片的传热因子、传质因子及摩擦因子随空气侧雷诺数和制冷剂进口温度的增加而减小,随相对湿度的增加而增加;修正后传热因子、传质因子和摩擦因子的关联式能够在±10%的误差范围内涵盖92.9%、96.4%和96.4%的试验数据,3种因子的平均误差分别为5.1%、5.9%、4.7%。该研究可为温室及相似环境下冷却除湿系统中亲水翅片管换热器的设计与应用提供参考。     

日光温室墙体与地面吸放热量测定分析

为研究日光温室土质后墙与地面对室内的放热情况,测定了晴、阴天气条件下土质后墙和地面的表面温度及热通量。结果表明,单位面积墙体与地面各自的放热量与室内太阳辐射密切相关,晴天夜间单位面积墙体放热量为 1.90 MJ/m2,地面放热量为1.36 MJ/m2,而阴天夜间单位面积墙体放热量为0.76 MJ/m2,地面放热量为1.34 MJ/m2。对于单位面积墙体和地面而言晴天墙体放热量大于地面,阴天地面放热量大于墙体,无论晴天与阴天地面全天放热总量总是大于墙体释放总量,且地面对周期热量变化的缓冲大于墙体。     

Analysis of Sewage-water Heat Exchanger withthe Function of Auto-de-fouling

A sewage-water shell-tube heat exchanger with the function of de-fouling was proposed and designed for sewage-source heat pump. Its new simulation program which relies on a distribution parameter computational method was set up. Then the model was solved with the method of Matrix Control. Based on the model, the distribution of bilateral fluid temperature were studied, under the conditions of different flow rates and heat exchange area before and after the de-fouling. Results showed that there will be heat anti-transfer phenomenon if the heat exchanger area is bigger than need and the region of this phenomenon was point out. Setting the function of auto-de-fouling in shell-tube heat exchanger and reducing the equipment's volume accordingly can make the sewage-water heat exchanger run in the best conditions.     

畜舍热交换芯体-风机热回收通风系统的热回收效果

热回收通风作为一种节能的通风换气方式,可缓解畜舍保温能耗与通风的矛盾。然而民用一体式热回收通风系统在畜舍中直接应用时存在通风量小、单位通风量的设备造价高等问题。该研究设计了适用于畜舍的新型节能热回收通风系统,并研究该热回收通风系统在以下3种不同配置条件下的热回收效果,探究该系统在畜舍中的较佳运行条件:板翅式热交换芯体配置不同迎面风速的热回收效果;新风依次经过2个串联连接的板翅式热交换芯体后的热回收效果;优化了板式热交换芯体与噪声小、风量大的轴流风机的参数配比后的热回收效果。结果表明:在舍内外温差为12.08℃,芯体配置迎面风速分别为1.05和0.86 m/s时,新风温度经过板翅式热交换芯体后分别升高了1.93和2.79℃,显热回收效率、热回收负荷和能效比分别为35.88%和43.63%、0.16和0.19 kW,1.37和1.61,两者显热回收效率均未达到冬季65%的节能标准。在舍内外温差为10.49℃时,新风依次经过串联的2个板翅式热回收芯体,经过第1次热交换后新风温度升高2.59℃,显热回收效率为52.11%,热回收负荷及能效比分别为0.39 kW,3.26;新风经过第2次热交换芯体时热回收作用甚微。优化板式热交换芯体与风机配比后,在舍内外温差为12.12℃,迎面风速为4 m/s时,新风温度升高8.23℃,显热回收效率为69.9%,能效比为8.0,达到了冬季节能标准。从该研究热回收效果看,第3种配置参数条件平衡了热回收效率及通风需求的关系,可满足畜舍大通风量及节能的需求。     

Performance analysis and application of three fluid separate type heat pipe exchanger

The temperature transfer matrix equations for three fluid separate type heat pipe heat exchangers with the same and different heat transfer area in each heat pipe row are obtained by establishing an analytical heat transfer model in the co current or countercurrent flow mode. Using the temperature transfer matrix equations of exchanger with the each row heat transfer area is similar. The relationships of heat exchanger effectiveness θ1, θ2 with M, NTU, U, Δti are derived in the co current or countercurrent flow mode. For the designing and checking calculation of the heat recovery device for the large hot blast stove in steel plant, the theoretical results can be used and it is proved correct in practical application.     

Influence of heat storage mode of domestic hot water on the performance of ground heat exchanger in ground-source heat pump system

The vertical U-tube ground-coupled heat pump system provides cold and heat for the controlling of indoor environment. Under the air-conditioning condition, the vertical U-tube ground-coupled heat pump system with heat recovery can provide domestic hot water. The influence of supplying domestic hot water on the heat transfer performance of ground heat exchangers is different under different operating modes in summer and winter. Through a project design of ground-source heat pump system, the influence of supplying domestic hot water under heat storage mode on the heat transfer performance of ground heat exchangers in summer and winter is respectively analyzed. The dynamic performance of heat exchangers under different working conditions is analyzed, and through numerical calculation, the heat transfer performance parameters of ground heat exchangers under different operating modes are obtained. From the calculation results, the adjusting methods based on the load characteristics of this project represent.     

竖直埋管换热器热响应半径计算方法

随着能源压力的日益增大,世界各国都十分重视可再生能源的利用与开发,地源热泵技术作为一种清洁、高效的可再生能源,近年得到了较快的发展。该文利用无限长线热源传热计算模型,讨论了介质内过余温度场的分布特性。结果表明：介质内温度响应在孔壁处最大,随离孔壁距离的增加呈指数衰减,随时间的增加而增大;热传播区域随时间的增加而增大,随介质的热扩散系数的增加而增大。针对工程中群埋管换热器情况,利用叠加原理计算群埋管的孔壁温度,定义换热器的热响应半径为其他钻孔引起的过余温度影响系数≤5％时相邻钻孔中心线之间的垂直距离。在大量计算分析基础上,提出了竖直埋管换热器热响应半径计算方法。计算结果表明该文方法具有较好的计算精度,竖直埋管换热器的热响应半径随岩土热扩散系数增大而增大,随持续运行时间增加而增大,随钻孔排数增加而增大,随着钻孔孔径增大而增大;钻孔布置方式不同对钻孔热响应半径的影响较明显,相同布置方式下钻孔直径对其热响应半径的影响较小。针对工程中常见的115和135 mm 2种孔径,绘制了不同岩土介质下钻孔单排、双排和三排以上布置时热响应半径-运行时间的关系曲线。工程算例表明该文方法简单方便,为工程设计提供了便利。     

冰水混合间接换热系统中换热器参数试验

利用北方地区冬冷夏热的特点,冬季冻冰蓄冷,夏季利用。采用间接换热冷量交换系统,有利于低碳节能和保护环境。该文对系统中换热器的参数进行了优化试验。以热交换器中的风速、流量、迎风面积、热管长度为影响因素,以热交换器的换热效率为目标,得到换热效率84%以上的较佳参数组合为风速2.54～2.93 m/s,流量0.72～0.80 m3/h,迎风面积11.93～13.51 dm2,热管有效长度7.99～9.95 m。该研究为利用自然冷资源间接换热冷量交换系统中热交换器的设计和应用提供依据。     

基于毛细管换热器的日光温室低温供暖系统设计

为将毛细管换热器应用于日光温室中,该文试验测试了毛细管换热器的热工性能和流动阻力,得到毛细管换热器在0.0306、0.0222和0.0139 kg/s流量下散热量与过余温度（20～50℃范围内）的关系曲线以及相应阻力和流量的变化关系曲线。在低于40℃的低温热水供暖状态时,在25～30℃的过余温度下毛细管换热器垂直放置时可提供258～323 W/m2的散热量,而水平放置时散热量达到307～381 W/m2。在此基础上,设计了一套采用生物质固体成型燃料供热的基于毛细管换热器的日光温室低温供暖系统,试验温室和对照温室建筑面积均为518.5 m2。测试结果表明,采用合理的供暖方案,在每天燃烧秸秆固体成型燃料125 kg能保证试验温室夜间平均冠层气温10℃以上,-15 cm土壤温度15℃以上,与对照温室相比,夜间平均气温、最低气温和-15 cm土壤温度分别提高了9.0、6.5和5.7℃。     

Experiment and Simulation on Heat Transfer Efficiency of Double pipe Heat Exchanger for River Water source Heat Pump

The river water source heat pump system is an important technique to utilize renewable energy in Chongqing and heat exchanger can influence overall energy efficiency of system obviously. A test was carried out to study the heat transfer efficiency of double pipe heat exchanger with semicircular reentrant tube. It was found that the heat transfer efficiency would increase while curvature of semicircular reentrant tube rose. And when the ratio of R to r was five, heat transfer efficiency for semicircular reentrant tube would be increased 2.5% than that of straight double pipe heat exchanger. Flow, temperature field and heat transfer process of semicircular reentrant tube were simulated with computational fluid dynamics(CFD) tool to study the heat transfer mechanism. The modified RNG κ ε Turbulence Model was adopted to ensure the accuracy of simulation analysis under the situation of rotary flow and great curvature. Thus, it was indicated that there was obvious secondary flow vertex in reentrant tube. And disturbance of vertex on boundary layer was the main reason for which heat transfer efficiency of double pipe heat exchanger would increase as curvature of semi toroidal reentrant tube rose. Based on the experiment and simulation, the recommended curvature for reentrant tube was proposed with the consideration of sediment in river water and heat transfer efficiency of heat exchanger.