直热式热泵热水器冷凝器结构优化试验研究

搭建了空气源热泵热水器试验台.在标准工况下,分别比较了普通套管式冷凝器,3套管式冷凝器和板式冷凝器对热泵系统运行性能的影响.结果表明,板式换热器在热泵热水器系统中换热性能大大优于另外两种常规换热器,使系统性能系数达到4.1,比使用其他两种冷凝器时系统的性能系数提高20％左右.试验结果为如何提高热泵热水器性能提供了依据.     

冷暖空调热水三用机的功能控制

介绍了一种多功能热泵热水机的工作原理及其在空调、供暖气和制热水多个模态运行时的控制逻辑要求;讨论了热泵的热水换热器三种加热形式:循环加热式、一次加热式和间歇加热式的特点,以及根据进水温度通过调节进水和中间循环水量来满足出水定温要求的方案.本文的研究工作对提升多功能热泵热水机技术具有重要的参考价值.     

几种新产品在民用建筑中的推广应用

本文主要介绍了比例式减压阀,浮动盘管换热器,电子水处理仪,远传水表这四种产品的工作原理,性能、应用方法及适应条件,兹例式减压阀既减静压又减动压,它在高层给水分区中的应用,可以取代分区水相,取消一组或数组加压水泵,节省建筑空高,降低结构负荷,减小电气设备装机负荷,经济效益明显,浮动盘管换热器采用自由浮动的螺旋铜盘管,可自动除垢,冷凝水过冷却,换热效率高,采用半即热式浮动盘管换热器,设备外形小,造价低;采用贮热式浮动盘管换热器,热水供应量、供水温度均比较稳定,电子水自理 与传统循环水、不系统防垢处理系统相比,系统简单、设备造价低,运行无需管理,几乎无运行费用。远传水表在近年的小康住宅设计中贯彻了建设部“表表出户”的方针,使水表可以在室外集中或分散设置,使于管理人员抄表,也可以结合计算机实行统一管理,随着我国经济的不     

海相沉积砂岩土壤源热泵供热性能的试验研究

根据海相沉积砂岩——设计了土壤源热泵热水系统.试验采用单因素法,在连续和间歇运行两种工况下研究不同热负荷下系统的运行情况及土壤换热能力(通过控制开启主机的数量和土壤换热井数量来改变热负荷大小);在主机停止工作后,让土壤换热器中的循环介质与大地进行充分换热,测试土壤换热器中循环介质的温度变化来判断埋管区土壤温度场的恢复能力,从而综合评价地源热泵热水系统的运行性能.     

微型电动汽车热泵空调系统设计与试验研究

为了提高某微型电动汽车有效续航里程,对其原有空调系统及换热器进行了改进设计与研究,新热泵空调系统采用4个电磁阀对其冷暖模式进行切换,通过焓差室对换热器和系统的性能进行了测试.首先比较了两种不同流程布置室外微通道换热器的换热能力;进而分别将原空调系统换热器和所设计换热器应用于该热泵空调系统,试验研究了压缩机转速和环境温度...     

地源热泵和毛细管吊顶辐射采暖系统启动过程联合供热特性试验研究

采用试验的方法,分析了3口90m井地埋管换热器换热性能、热泵机组供热性能、毛细管辐射板供热能力、辐射板加热层温度、地板表面温度以及室内温度的变化特性.经过研究,得出了上海松江区大学城区域的地质条件下,热泵机组供暖期间,最大单位井深换热量78W/m.地源热泵机组提供28~35℃的低温热水时的COP值与制取40～50℃热水相比大大提高,节能效果显著.室内采用毛细管吊顶辐射采暖时,当进水平均温度37.5℃时,最大换热量达到了3512W(171W/m2),与进水平均温度29℃相比,其最大换热量增加了66.7%;另外,室内竖向空气存在明显温度梯度.     

三种管壳式换热器传热与流阻性能对比实验研究

弓形折流板换热器壳程流体横向冲刷换热管时存在流动阻力大和传热死区大等缺点,折流杆换热器壳程流体纵向流动,但当壳程流体雷诺数Re较小时传热性能不佳。为克服上述缺点,研究开发了一种新型高效节能的斜向流管壳式换热器,该换热器壳程流体总体呈纵向流动,局部区域流体倾斜冲刷换热管束。对斜向流换热器与折流板换热器和折流杆换热器传热与流阻性能的对比实验研究表明,在同等壳程流体流量下,斜向流管壳式换热器的传热系数、压降和综合性能均介于折流板换热器与折流杆换热器之间。研究结果为管壳式换热器升级换代提供了一种新技术和新装备,也为热力系统中换热器选型和结构优化设计提供了重要依据。     

冷凝式燃气热水器的热工性能实验研究

介绍一种新型结构冷凝式换热器,换热管采用不锈钢材料的螺旋盘管结构,并对新研制的冷凝式燃气热水器样机热工性能进行实验。在不同的运行工况下测定了热水器的热效率、排烟温度、CO排放浓度。并分析其热效率与热负荷、热水流量、排烟温度的关系,CO排放浓度与热负荷的关系。研究表明,在额定热负荷下,样机热效率能达到96%以上,达到国家一级能效标准,且CO排放达标。该结构形式的热水器具有结构紧凑、耐腐蚀、热效率高等优点,具有较大的开发价值。     

二氧化碳热泵热水器水箱温度对系统性能的影响

对于二氧化碳热泵热水器性能的提升,大部分研究主要关注压缩机效率、换热器效率的提升、膨胀机和喷射器的应用以及控制方式的优化,但关于水箱结构对系统的性能影响研究较少.普通水箱的应用对系统性能影响很大,特别是制取高温热水时,性能影响更大.另外,水箱的设计和制造也相对压缩机、换热器等主要部件的优化容易,成本也较低.本文试验测量了不同水箱温度条件下,二氧化碳热泵热水器的性能变化,通过分析提出了改善性能的方法.     

几种新产品在民用建筑中的推广应用

本文主要介绍了比例式减压阀、浮动盘管换热器、电子水处理仪、远传水表四种产品的工作原理、性能、应用方法及适用条件。比例式减压阀既减静压又减动压，它在高层给不分区中的应用，可以取代分区水箱，取消一线或数组加压水泵，节省建筑空间，降低结构负荷，减小电气设备装机负荷，经济效益明显。浮动盘管换热器采用自由浮动的螺旋铜盘管，可自动除垢，冷凝水过冷却，换热效率高，采用半即热式浮动盘管换热器，设备外形小，造价低；采用贮热式浮动盘管换热器，热水供应量、供水温度均比较稳定。电子水处理仪与传统循环水、热水系统防垢处理系统相比，系统简单，设备造价低，运行无需管理，几乎无运行费用。远传水表在近年的小康住宅设计中贯彻了建设部“三表出户”的方针，使水表可以在室外集中或分散设置，便于管理人员抄表，也可以结合计算机实行统一管理。     

A study on method of reducing condensation for total heat exchanger under humid conditions

An experimental study was performed to reduce the condensation under very humid conditions for a total heat exchanger. The hydrochromic ink was used to detect the condensation within the total heat exchanger. Condensation in a total heat exchanger can be reduced by decreasing the flow rate of the supply air. The other method of decreasing the flow rate of the exhaust air can also be used to reduce condensation. However the flow rate of the exhaust air has to be less than half of the supply air flow rate for the tested total heat exchanger.     

Thermal performance of a spirally coiled finned tube heat exchanger under wet-Surface conditions

This paper is a continuation of the authors’ previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data.     

基于模糊数学的工业换热器除垢自适应注水系统设计

分析了工业换热器的服役工况条件,研究了流动-传热环境下的铵盐结垢机制,明确了换热器管束内结垢的影响因素,着重探究了注水对铵盐结晶的影响。基于铵盐结垢形成机制,设计了一种基于模糊数学的换热器除垢自适应注水系统。该系统对来自温度变送器、压力变送器和流量变送器的换热器进出口温度、压力和流速信号进行误差分析,以三类信号的平均相对误差及其变化率作为模糊控制系统的输入量。采用模糊数学控制调节阀的阀门开度,实时调节不同服役工况下清洗铵盐垢物所需要的注水量,并采用该方法计算了某一实际工况下所需的注水量。该文设计的系统解决了间歇性注水盲目性和滞后性的弊端,且符合节能环保的理念。     

Air to air fixed plate enthalpy heat exchanger, performance variation and energy analysis

The thermal performance of a Z shape enthalpy heat exchanger utilising 70 gsm Kraft paper as the heat and moisture transfer surface has been investigated. Effects of different inlet air humidity ratio conditions on the heat exchanger effectiveness and on the energy recovered by the heat exchanger have been the main focus of this investigation. A typical air conditioning cooling coil which incorporates an enthalpy heat exchanger has been modelled for tropical climate. Under test conditions, results have shown that latent effectiveness and the moisture resistance coefficient have strong dependency on the inlet air humidity ratio. Moreover, the latent effectiveness has been found to be strongly dependent on the moisture resistance coefficient rather than the convective mass transfer coefficient. Finally, annual energy analysis for Singapore weather conditions have also shown that energy recovered under variable inlet air conditions is 15% less than that recovered under constant inlet air conditions for the same heat exchanger.     

多孔介质模型在板翅式换热器数值模拟中的应用

利用FLUENT软件中的多孔介质模型,对板翅式燃气热水器换热器芯体内流体的流动与传热进行三维数值模拟.计算分析了不同操作参数条件下,换热器芯体的流场分布特点,计算结果与热水器样机测试实验结果吻合,表明该模型的应用是切实可行的.     

Predicting yearly energy recovery and dehumidification enhancement with a heat pipe heat exchanger using typical meteorological year data in the tropics

An investigation was carried out to study the effect of an air-to-air heat pipe heat exchanger on the energy recovery and dehumidification enhancement of the air conditioning system in tropical climates. For this purpose, the performance of a heat pipe heat exchanger, which was experiencing tropical ambient air in its evaporator section and fan coil unit, was monitored during one week of operation (168 hours) to find out the relevant performance characteristic curves. Then, empirical equations, which were extracted from the performance characteristic curves, were employed for the hour-by-hour prediction of energy recovery by the heat pipe heat exchanger and dehumidification for the whole year using TRNSYS software. The investigation showed that the heat pipe heat exchanger can pay for itself in 1.9 years. Moreover, it was shown that the dehumidification capability of the cooling coil can enhance up to 6% with the added heat pipe heat exchanger.     

A study on energy saving of cooling/reheating system using compact heat exchanger

When circulated air passes through the cooling coil in an air-conditioning system, the air is over-cooled to eliminate the moisture and decrease the temperature. The cooled air is then reheated to recover the temperature. The purpose of the present study was to evaluate the performance of a cooling/reheating system with regard to both cooling and reheating energy savings affected by exchanging heat between the cooled air and the reheated air with a compact heat exchanger. The thermal and dehumidification behaviors of the system were evaluated experimentally and then compared with simulation data. The results show that the energy saving rate was as high as 50% under the present experimental conditions and was affected by the face velocity of the heat exchanger, the inlet temperature, the inlet humidity ratio, and the effectiveness of heat exchanger. Furthermore, the experimental data were found to be in fairly good agreement with the simulation data.     

Experimental study on heat transfer characteristics of water-spray-bed heat exchanger

An experimental study was conducted on a water-spray-bed heat exchanger to investigate the heat transfer characteristics. A laboratory-scale test rig was built and its heat transfer characteristics were investigated with respect to various design and operation parameters such as the water spray flow rate, exhaust gas flow rate and number of tube rows. It was found that the implementation of the water spray increased the heat transfer rate to about 1.3 - 2.2 times that of a heat exchanger without water spray, although with a slight increase in the pressure loss. It was thus confirmed that the water spray was effective for enhancing condensing heat recovery from an exhaust gas.

     

管板间隙对管壳式换热器流动与传热的影响研究

管壳式换热器中,由管板间隙引起的漏流不利于换热器的传热。通过一种新型网格生成方法,对所建立的三维实体模型进行网格划分,并利用CFD软件Fluent进行数值模拟,研究不同情况下壳程与管程的流动与传热特性。计算中采用标准k—ε模型,SIMPLE算法,压力方程为标准格式。将模拟结果引入换热器评价指标,全面分析管板间隙对管壳式换热器流动与传热的影响。     

基于圆柱源理论的热泵垂直U型地埋管模拟分析

基于圆柱源理论,建立了U型地埋管换热器传热模型,并进行了数值求解。计算结果表明,夏季U型地埋管换热器在给定进口温度和流量时,连续运行48h后,地埋管出口水温、壁面温度和单位延米换热量基本趋于稳定。单位延米换热量与热响应实验数据误差为3%,验证了模型的准确性。以某地区空调系统地埋管换热器设计为例,模拟分析了不同负荷特性下地埋管换热器的换热性能。模拟结果显示整个夏季运行中地埋管最大进口水温低于设定值37℃,满足机组运行温度要求,设计合理。可为实际的工程应用提供参考。