家用变频热泵型空调器室外机换热器流路布局优化设计

对家用变频热泵型空调系统性能随Φ7 mm管室外换热器流路布局的变化进行试验研究,结果表明:热泵型空调用的室外换热器制冷工况和制热工况对应的最佳分路数不同,制冷工况时的最佳分路数少于制热工况,且分路数对制热工况性能影响更大。室外换热器流路布局设计应首选额定制热工况作为设计工况,且应优先考虑该工况下的最佳分路数对应的流路,再在此基础上适当减少制冷剂低干度区的分路数。对于用于3 500 W制冷量的二级能效R32家用变频热泵型空调器用的室外换热器,最佳分路数为3,单支路换热管长度不超过11.2 m,最佳流路布局为3进1出的"7U+7U+7U-3U"流路。     

基于气体旁通蒸发技术的变频房间空调器APF提升研究

对于空调器用翅片管换热器,制冷剂在蒸发/冷凝两种工况下的制冷剂侧压降特性差异较大,导致换热器蒸发模式下的最佳分路数远大于冷凝模式下的最佳分路数,而常规翅片管换热器无法实现制冷剂流路与运行工况之间的良好匹配.针对这一问题,本文通过实验研究了气体旁通蒸发技术对不同负荷下房间空调器性能及APF的影响.实验结果表明:制热模式下...     

风速对不同流程数CO2蒸发器性能的影响

为研究迎面风速对不同流路数CO₂翅片管蒸发器性能的影响,本文建立分布参数模型对蒸发温度为-25℃,风速为0.5～4 m/s条件下5种流路数CO₂翅片管蒸发器的制冷剂压降、换热量、温度分布及传热系数的变化进行分析,并通过实验验证了蒸发器模型的可靠性。蒸发器模型的换热量、制冷剂压降和风侧压降等参数模拟值与相同工况下实验值的误差均在±4%以内。结果表明:同一流路数蒸发器的换热量、制冷剂压降及传热系数均随风速的增大而增大,而其涨幅随风速增大而减小,综合考虑换热效果和能耗可得最佳风速范围为2.5～3.5 m/s;在一定风速条件下,蒸发器设计时在合理范围内选择较多流路数可有效提升蒸发器换热性能并增强换热均匀性,本次实验中24流路蒸发器为最佳设计方案。     

房间空调器采用3mm铜管的设计与性能分析

房间空调器采用更小管径的铜管可以使换热器更加紧凑、高效和环保,因而开发3 mm铜管换热器代替现有的5 mm管换热器是未来房间空调换热器的一个重要发展方向。本文提出了开发3 mm管换热器的技术思路,包括通过定量计算强化管和光管的换热与压降特性来确定管型;通过基于换热性能和压降的流路参数和管径的寻优算法来优化流路和管径。设计结果表明,某典型的3,500 W房间空调器从5 mm强化管改为3 mm光管后,其内、外机的换热性能在制冷工况下分别提升12.7%、5.7%,在制热工况下各提升10.1%、15.4%;压降均在50 k Pa以内;铜的用量下降57.2%、铝的用量增加2.1%。     

微通道换热器空调系统性能试验分析

本文通过对两套采用微通道换热器的KFR-72LW空调器样机（1号机：室内外换热器均采用微通道换热器;2号机：室外机为微通道换热器,室内机为管翅式换热器）,分别进行性能测试,对比分析采用微通道换热器与管翅式换热器的空调器性能差异。试验结果分析显示：微通道换热器空调器具有高效（强制冷性能）、减排（减少制冷剂充注量）、低成本（换热器小型化）等优点;但制热工况下,因室外机采用微通道换热器,换热面积大幅度减小,蒸发压力过低,导致制热效果不良、系统频繁除霜等问题,有待于进一步研究解决。     

分体式空调器长连接管制冷剂追加量的试验研究

基于制冷量为12 kW的风管送风式空调(热泵)机组进行试验研究,分析节流位置、工况等因素对长连接管制冷剂追加量的影响,得出9.52 mm液管和15.88 mm气管条件下R410A制冷剂追加量的参考值。研究发现,对于单冷型空调器,节流位置会对长连接管的制冷剂追加量产生较大影响,室内机节流时的追加量大于室外机节流;而对于热泵型空调器,节流位置对长连接管制冷剂追加量的影响较小。     

热泵型空调器运行特性的实验研究

用空气焓差实验法,在制冷工况下对一台热泵型空调器进行最佳充注量的实验研究,同时,分别在制冷工况和制热工况下测量冷凝器和蒸发器管壁的温度分布。实验结果表明,空调系统中存在一个最佳制冷剂充注量,使得空调系统的制冷量和能效比达到最大值。根据实验结果,分别给出在制冷工况和制热工况下进行冷凝器和蒸发器换热计算时,制冷剂与管壁之间的平均温差。     

机房空调用平行流冷凝器的设计及性能测试

针对数据中心全天候空气调节需求,采用平行流冷凝器设计空调样机,在标准焓差法试验室进行性能试验。结果表明:组合式平行流冷凝器采用两进一出流程的布置方式,并以3:1比例分配扁管,冷凝效率高;制冷冷凝器和热管冷凝器间隔3~5 mm进行叠加组合,节省机组空间,优化空气侧换热效率;不同工作模式下,冷凝器均具有较好制冷能力;平行流换热器的换热系数升高与压降增大是相辅相成的,适当增加系统制冷剂循环流量能够增强换热效果。     

全铝钎焊式平行流冷凝器性能对比试验

对6种全铝钎焊式平行流冷凝器进行冷凝换热性能对比试验,与双排9.52mm翅片管换热器进行对比,得到风阻、冷凝能力和综合冷凝能力对比试验曲线。对比结果表明：全铝钎焊式平行流冷凝器具有较高的综合冷凝性能和单位体积换热量,部分规格的平行流冷凝器的单位迎风面积的冷凝能力高于对比用翅片管换热器。     

铜管管径对翅片管式冷凝器性能和经济性的影响

针对大型风冷式制冷机组的应用,分析铜管管径变化时翅片管式换热器换热面积、管侧容积、换热量和压降变化情况,并进行材料成本和单位换热量材料成本的比较。研究结果表明,在合理选择管列间距和管排间距的前提下,7.94 mm和7 mm的换热器都可以达到9.52 mm换热器的换热量,并实现约10%的成本节约。     

扁平铜管翅片管冷凝器性能试验

对一种扁平铜管百叶窗翅片管换热器（FTHX）进行单体冷凝性能和整机制冷性能试验,并与现行铜圆管翅片管换热器（CTHX）在相同工况下进行对比。试验结果表明：FTHX具有风阻低、制冷剂流阻高和系统制冷剂充注量少的特性;FTHX综合冷凝性能高于φ7mm铜管换热器但略低于φ9.52mm铜管换热器;FTHX整机制冷能力和能效比均略低于单排φ9.52mm铜管换热器。     

过冷段翅片管换热器的试验研究

对过冷段翅片管换热器对空气源热泵冷热水机组系统性能的影响进行试验研究。过冷段翅片管换热器通过横向导热和强制对流换热可增大制冷剂液体过冷度，制热工况下，可使系统性能系数COP提高约19％，并有效降低翅片表面结霜。     

Performance evaluation of a CO2 heat pump system for fuel cell vehicles considering the heat exchanger arrangements

A novel CO₂ heat pump system was provided for use in fuel cell vehicles, when considering the heat exchanger arrangements. This cycle which had an inverter-controlled, electricity-driven compressor was applied to the automotive heat pump system for both cooling and heating. The cooling and heating loops consisted of a semi-hermetic compressor, supercritical pressure microchannel heat exchangers (a gas cooler and a cabin heater), a microchannel evaporator, an internal heat exchanger, an expansion valve and an accumulator. The performance characteristics of the CO₂ heat pump system for fuel cell vehicles were analyzed by experiments. Results for steady and transient state performance were provided for various operating conditions. Furthermore, experiments to examine the arrangements of a radiator and an outdoor heat exchanger were carried out by changing their positions for both cooling and heating conditions. The arrangements of the radiator and the outdoor heat exchanger were tested to quantify cooling/heating effectiveness and mutual interference. The improvement of heating capacity and coefficient of performance (COP) of the CO₂ heat pump system was up to 54% and 22%, respectively, when using preheated air through the radiator instead of cold ambient air. However, the cooling capacity quite decreased by 40–60% and the COP fairly decreased by 43–65%, for the new radiator-front arrangement.     

平行流换热器在江水源热泵中的应用研究

基于已在汽车空调中广泛使用的平行流换热器,对其采用水冷方式以应用于长江上游地区热泵系统。结果表明,水冷对平行流换热器的传热特性影响很大,水冷比空冷的冷凝器出口过冷度提高了33℃,传热系数可达到1.9kW/(m2.K),使得整个空调系统的COP提高了18.4%,从而减少制冷剂充注量60%,换热器体积减小85%,在维护和安装方面具有很大优势。本试验研究是长江上游地区地表水水源热泵系列研究之一,可供平行流换热器在水冷式热泵空调上的进一步研究、设计和制造及应用作参考。     

Performance evaluation of a heat pump cycle using NARMs by a simulation with equations of heat transfer and pressure drop

Simulation analyses for a vapour compression heat pump cycle using nonazeotropic refrigerant mixtures (NARMs) of R22 and R114 are conducted under the condition that the heat pump thermal output and the flow rate and inlet temperatures of the heat sink and source water are given. The heat transfer coefficients of the condensation and evaporation are calculated with empirical correlations proposed by the authors. The validity of the evaluation method and the correlations is demonstrated by comparison with experimental data. The relations between the coefficient of performance (COP) and composition are shown under two conditions: (1) the constant heat transfer length of the condenser and evaporator; and (2) the constant temperature of refrigerant at the heat exchanger inlet. The COP of the NARMs is higher than that of pure refrigerant when the heat transfer lengths of the condenser and evaporator are sufficiently long.     

基于复合热源的热泵型空调器

提出将空气-水作为热泵型空调器的复合热源。根据当前的研究状况,初步设计空气-水复合热源热泵型空调器,利用热力学原理分析该空调器的工作循环和特点,结果表明该空调器的制冷性能高于空气源热泵空调器,制热和室外换热器结霜状况得到一定改善。     

System performance characteristics of an air conditioner over a range of charging conditions

A popular type of residential air conditioner in the USA is the split system. These systems have an outdoor unit which houses the condenser, condenser fan, compressor and controls. A separate indoor unit houses the evaporator, expansion device and evaporator blower. As the refrigerant charge of these systems is adjusted during field installation, the potential exists for not setting the charge exactly to the manufacturer's specifications. The objective of the work reported here was to quantify the influence of the refrigerant charge on the steady-state and cyclic operation of a residential split-system air conditioner. A 3 ton unit with capillary tube expansion was tested. The charge was systematically varied to determine its effect on system variables such as capacity, flow-rate, evaporator superheat, power consumption and seasonal energy efficiency ration (SEER). The results indicated a large degradation in capacity for undercharging than for overchar at a given temperature. However, the trends in capacity as a function of temperature for undercharging were different from those for overcharging. The difference in trends was found by close examination of the refrigerant flow control provided by the capillary tube. Other results indicated that small amounts (5%) of undercharging caused as much as a 6% drop in the SEER.     

室外换热器分液装置的实验研究

制冷剂分配不均现象是室外换热器研究的重点内容.本文设计了两种隔板形式,共制作7种样件放置于换热器集管中进行实验研究.通过实验分析了换热器用作蒸发器的6种工况与用作冷凝器的4种工况下的制冷剂分配情况及换热性能.结果表明:本文利用挡流板实现了良好的制冷剂分配效果,两种挡流隔板(A和B)的加入均有助于改善换热器制冷剂分配不均...     

R290微通道冷凝器性能优化及其充注量分析

采用仿真方法,以R290家用空调器用微通道冷凝器为研究对象,比较不同流路布置方案对冷凝器性能的影响,并对外形尺寸相同的微通道冷凝器与翅片管冷凝器充注比进行对比。结果表明：流程布置及各流程扁管分配对微通道冷凝器性能有较大影响,存在较优的流程数及流程扁管数;R290微通道冷凝器充注比与Ф5mm单排冷凝器充注比水平相当,经进一步结构优化后,微通道冷凝器将比小管径换热器在降低冷凝器充注比和材料成本方面具有更大的潜力和优势。