CO_2热泵热水器的系统设计及试验研究

设计搭建了蒸发器和气冷器均采用套管式换热器的跨临界CO2热泵热水器性能测试试验台,在制冷剂充注量1.23kg时,通过调节膨胀阀的开度和控制气冷器的水流量来研究系统性能。结果表明:该机组能在较高COP(3.2)下制得65℃的热水,并可以在COP不低于2.0情况下制取80℃的热水;气冷器水流量对系统的COP、出水温度以及系统的排气压力影响最大;高效的换热器可以在压缩机排气温度一样的情况下提高出水温度,使系统在制取高温水时有更高的COP。     

一种直热式冷暖空调热水三用机的研究

介绍了一种由四个分立循环构成的冷暖空调热水三用机的系统流程和工作原理,首次公开了一种热泵用的直热储热两用型热水换热器的基本结构,工作原理,用实验和数值模拟方法,研究了这种新型换热器在零出水量作储热式换热器和在有不同出水量以及定温出水时的换热性能,并比较了同传热面积的浸泡式盘管换热器的性能.研究表明,带导流套筒的新换热器与市场上的家用热泵热水器的浸泡式盘管换热器相比,在连续供热水时,换热能力高1倍多,在零流量静态加热时,换热能力高10%以上.     

Performance evaluation of a water-to-water heat pump with a floor panel heating system

The performance of heat pump is severely degraded as the temperature of the heat source is decreased. For air source heat pumps, this results in a serious mismatch of heat pump output and space heating demand. Although the outdoor temperature is below 0°C, the use of a water-to-water heat pump with a floor panel heating system can operate for extended periods of time without frost-defrost cycling and therefore at a high seasonal efficiency. This paper focuses on the performance of a water-to-water heat pump that uses well water as a heat source and a floor panel heating system as a sink.     

某医院住院楼地源热泵热水系统性能测试与研究

简单介绍了某医疗建筑的能耗情况和医院的工程概况,并对本医院的供热水系统——地源热泵系统的运行情况进行测试和性能研究,包括对机组冷冻水的进/出温度的测试、土壤换热器吸热效率的测试、机组的能效测试等,并分析冷冻水的进/出温度、流量及其他因素对系统能耗产生影响情况,并得出系统冷冻水流量在4.3～4.8kg/s范围内为最佳流量段,此时土壤换热器的吸热效率较高,土壤换热器单位管长换热量在35.5W/m左右,机组的能效比值达4.0及以上,系统的能效比达3.7及以上;最后对本系统进行了节能计算及效益分析,可看出此系统节能效益非常可观。     

热管废热回收蒸发器在浊水余热回收中的应用

针对污水的特性,为避免生活污水与热泵工质R22产生交叉污染,从而导致系统不能正常运行的可能性,提出在污水与热泵系统工质R22之间采用一个热管换热器,得出在系统增加了一个热管换热器的情况下,污水流量一定时,热泵制热量,性能系数COP值,热泵系统R22工质蒸发温度,污水废热回收热量随污水进口温度的增大而增大,其中热泵工质蒸发温度的增幅最大,达到65.79%,废热回收热量的增幅最小,为6.8%,污水入口温度一定时,热泵制热量,性能系数COP值,热泵工质蒸发温度,废水回收热量随着污水流量的升高而升高,但是热泵工质蒸发温度的和性能系数COP值的增幅减少,热泵制热量,热管工质蒸发温度以及废水回收热量的增幅缓慢增加.     

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...     

Convective heat transfer behaviour of water-ethylene glycol-mixture with silver nanoparticles under laminar flow conditions

In this work, we report the forced convective heat transfer performance and pressure drop of aqueous ethylene glycol seeded with silver nanoparticles for low temperature applications. Experiments were performed in a tube in tube counter-current heat exchanger using silver nanofluid as the hot fluid under laminar flow conditions. In this study, water-ethylene glycol mixture with 70:30 volume percent was used as the base medium. Silver nanofluid was allowed to flow through inner tube of the heat exchanger for varying nanofluid mass flow rates from 5 g/s to 30 g/s and three inlet temperatures of nanofluid viz. 2 °C, 5 °C and 10 °C. The increments in thermal diffusivity and viscosity are found to be ~37 % and ~69 % at 0.45 vol%, respectively. The enhancement in heat transfer coefficient at highest mass flow rate is found to be ~94 % for 0.45 vol%. The pressure drop in the silver nanofluid increases with respect to increase in volume percentage of nanoparticles due to increase in viscosity.

     

复合源水环热泵空调系统分析与研究

提出了一种采用空气源和电加热复合的辅助能源形式的复合源水环热泵空调系统,并对不同室外温度下建筑不同内外区冷热负荷比的情况下该复合源水环热泵空调系统的性能进行了分析与研究.将复合热泵循环系统能耗和使用锅炉的传统水环热泵空调系统的能耗进行了比较,体现出复合系统具有较高的能效比.分别计算了不同室外温度下建筑内外区冷热负荷比为2∶8和4∶6时,不同循环水温对复合热泵循环系统的能耗的影响,得出了最佳循环水温的范围.     

The effect of ambient air condition on heat transfer of hot steel plate cooled by an impinging water jet

It has been observed that the cooling capacity of an impinging water jet is affected by the seasonal conditions in large-scale steel manufacturing processes. To confirm this phenomenon, cooling experiments utilizing a hot steel plate cooled by a laminar jet were conducted for two initial ambient air temperatures (10°C and 40°C) in a closed chamber, performing an inverse heat conduction method for quantitative comparison. This study reveals that the cooling capacity at an air temperature of 10°C is lower than the heat extracted at 40°C. The amount of total extracted heat at 10°C is 15% less than at 40°C. These results indicate the quantity of water vapor, absorbed until saturation, affects the mechanism of boiling heat transfer.     

Experimental study on nanofludic heat pipe hot chuck plate in semiconductor wafer baking process

The temperature uniformity on a heat pipe hot chuck (HPHC) during semiconductor wafer processing has been an important factor to critical dimension (300 mm) uniformity as the feature size of semiconductors decreases and productivity density increases due to the new process of nano size special manufacturing technology. To design the present heat pipe hot chuck system, which has enhanced temperature uniformity for the wafer process, the heat distribution of the system was analyzed experimentally with various working fluids such as water, TiO₂, ATO, ITO, Al₂O₃, and Ag-nanofluids and 8 cell structures. Unlike the conventional solid state chuck, the present heat pipe hot chuck system consists of a heat pipe containing specially charged working fluid. Various working fluids have been tested to find best temperature uniformity feature on the top surface of hot chuck. TiO₂-nanofluid was used and tested as the working fluid of the heat pipe hot chuck system in this paper. The temperature uniformity of upper surface was sustained in the range of ±1°C. A nano-porous layer was observed on the surface with the good result of surface temperature uniformity compared with distilled water.     

集成管箱型管壳式换热器的设计分析

空调热泵系统中所用的CO2跨临界循环管壳式换热器，管侧流动的是CO2工质，换热管的内侧压力相对较高，高压大约为10MPa；壳侧流动的是水，基本是常压。采用高温高压换热器需要按照压力容器设计标准，会使整个换热器设备较为笨重，并会造成系统设备成本提高。针对CO2跨临界循环的特定要求，设计出了耐高压防泄漏的集成管箱型换热器，在确保安全性的同时，使系统结构紧凑，技术难度降低，从而使成本得到有效控制，可以促使CO2跨临界循环更快的走向实际应用。文中还对换热器管路的安全性进行了分析，并给出了准确度较高的可用关联式来计算CO2流体在气体冷却器和蒸发器管内的换热系数。     

Application of thermosyphon air-preheater for energy thrift from a furnace in a hot forging process

This research studied the heat transfer of the thermosyphon air-preheater. An empirical model was developed to predict heat transfer and applied to compute the thermosyphon air-preheater in a hot brass forging process. The thermosyphon air-preheater was designed, constructed and tested under medium temperature operating conditions with inlet hot gases, ranging between 390–440 °C in terms of using water as the working fluid with a 50 % fill by volume of the evaporator section. The experimental setup was comprised of a circular fin with 0.013 and 0.020 m internal diameter bare stainless steel tubes, with 0.015 m long evaporator and condenser sections. The thermosyphon air-preheater model had 6 rows, each composed of 4 columns. Experimental results found that the hot gas temperature was increased from 390 to 440 °C, the heat transfer rate increased. If the internal diameter changed from 0.013 to 0.020 m, the heat transfer rate slightly increased. The predicted results agreed well with the experimental data. This thermosyphon air-preheater has been designed, manufactured and tested for heat recovery in industry using medium temperatures ranging between 300-500 °C to recover flue gas energy from the furnace in a hot brass forging process.     

复合地源热泵系统土壤换热器预测模型研究

在复合式地源热泵系统中控制策略存在着极大的优化空间,本文提出以土壤换热器与冷却塔两者出口水温作为控制依据的运行策略,为实现此控制方法,需要建立准确的预测模型.本文运用人工神经网络(ANN)实现土壤换热器侧出口水温的预测,研究复合式地源热泵系统不同运行模式下预测的可行性与准确性,并与动态数值模拟结果比较.结果表明利用人工神经网络可以准确预测土壤换热器的出口水温,且模型具有较好的泛华能力,最大误差不超过0.25℃.     

Heating performance characteristics of stack coolant source heat pump using R744 for fuel cell electric vehicles

The objective of this study is to investigate the performance characteristics of a stack coolant source heat pump using R744 with a stack coolant heat source for fuel cell electric vehicles under cold weather conditions. Electric heaters are currently used in fuel cell electric vehicles, and the high levels of energy consumption involved lead to lower fuel efficiency and a reduction in the vehicle??s driving range. In order to improve the efficiency of the fuel cell electric vehicles in this study, a heat pump using R744 as a refrigerant and making use of wasted heat from the stacks is developed to cover the heating capacity. This heat pump is tested and performance optimized for stack coolant heat recovery under the compressor speeds, air temperatures, and flow rates of the interior heat exchanger, as well as the coolant flow rates of the CO₂-coolant heat exchanger. In addition, the heating capacity of the tested system was sufficiently attained over 5.0 kW at the coolant flow rate of 5.0 l/min under extremely cold weather conditions of ?20°C.     

房间空调与供热水耦合的CO2跨临界循环系统

房间空调与供热水耦合的CO2跨临界循环系统，充分利用CO2作为自然工质的独特性能，利用气体冷却器放出的热量提供所需生活热水。该系统结构紧凑，而且能够满足制冷、制冷 热水、热水、制热、制热 热水五种工况需求：通过对其进行技术可行性、全年能耗和综合性能系数进行分析，结果表明房间空调 热水的CO2耦合系统在能源利用、环境安全和经济运行等方面都具有优势和潜力。     

空气源热泵室外换热器翅片管的融霜过程分析

空气源热泵因其供热效率高而得到广泛应用,但是室外换热器的结霜问题导致了其供热效率的下降。针对空气源热泵室外换热器单管的融霜过程,搭建了单翅片管融霜实验台,使该单根翅片管分别以结霜和融霜2种模式运行。融霜过程分别选择40,30,20,10,5℃的循环溶液,同时对融霜过程进行理论分析。试验以及理论分析结果表明:在不同的循环溶液温度下,随着循环溶液温度的升高,融霜速率逐渐增加且变化趋势加快;循环溶液温度的高低对融霜过程产生程度不同的影响,存在最佳循环溶液温度,可以使得除霜效率达到最高。     

富水土壤源热泵供冷采暖机组运行特性研究

介绍了作者自主设计实施的土壤换热器与冷却塔并联的耦合型地源热泵空调系统,运用单因素方法,研究了冬夏两季热泵机组的运行特性;研究结果表明:夏热冬暖地区,本实验系统夏季采用热泵机组匹配土壤源释热的制冷效果一般,制冷工况热泵机组能效比约3.66,系统能效比约2.7;冬季采用热泵机组向建筑物供暖效果较佳,系统能效比达3.4以上.     

即热式空气源变频热泵热水系统性能的试验研究

介绍了一种即热空气源变频热泵热水系统,分析了水路模块与热泵模块的理论耦合,得到冷凝器出水流量和温度与热泵系统制热量的关系,以及承压水箱流量和温度与热泵系统制热量的关系。测试了机组在变工况下给用户提供42℃、6L/min热水的的运行特性,结果表明:运行时压缩机排气比循环加热式热泵热水器的排气温度和压力低并且稳定;运行的环境工况范围大,即在高温43℃和低温-7℃均可运行;制热COP随环境变化呈抛物线状变化,且在43℃、20℃和-7℃时,制热COP分别为12.6、4.5和3.8。     

Thermal characteristics of louvered fins with a low-reynolds number flow

A heat recovery system is crucial for the effective use of energy where heat rejection from production processes is unavoidable and must be reused. The response of the louvered fins to the low-Reynolds number hot gas is yet to be reported in the literature for the application of a heat exchanger on low-speed hot plume arising from heat sources in production processes. This study focuses on the effects of the louvered fin heat exchanger’s design parameters, which include the louver pitch and louver angle, on the convective heat transfer, which defines the thermal interaction between the hot, buoyant, naturally-induced air and the louvered fins. The resulting Colburn factors (j) are compared with those derived under forced convection with a similar range of low Reynolds number (233 to 1024). All experiments are done on a 15:1 scaled-up model. The fin aspect ratios between the fin spacing and louver pitch are set at 0.75, 1, and 1.5, while the louver angles are set at 18°, 23°, 30°, 35°, and 40°. The Colburn factor strongly depends on the louver angle, especially at the lower range of the Reynolds number. The decreasing aspect ratio induces more hot buoyant air into the louver-formed channels, increasing the heat transfer rate. When the fin angle increases towards 30°, a larger Colburn factor is produced. However, the heat transfer characteristic drops as the angle goes beyond 30°. The highest j for the low speed flow is attained when the louver angle is 30° and the fin aspect ratio is 1.     

混合式地源热泵夏季运行的试验研究

分析了混合式地源热泵的控制方法和控制参数。通过试验对比了在相同运行方式下冷却塔与地埋管串、并联时混合式地源热泵的运行结果,得出了基于系统综合效率与热平衡条件下的南京地区较合理的混合式地源热泵连接与运行方式。