蒸发冷却式冷凝器用于房间空调器的性能研究

针对采用蒸发冷却式冷凝器的房间空调器性能进行理论分析和对比实验研究。研究结果表明:蒸发冷却可有效提高翅片管式冷凝器的冷却效果和空调器的性能;采用厚度为70mm的CELDEK5090型纸质填料且淋水量为0.053kg/s,当环境温度为35℃时,空调器的能效比EER值提高了15.3%;当环境温度为39℃时,空调器的能效比EER值提高了11.5%。     

一种新型直接蒸发冷却空调机的性能测试

阐述新型直接蒸发冷却空调机的结构和原理，并详细讨论复合纤维填料的性能。用焓湿图分析空气处理过程，同时给出相应于不同空气条件的试验数据，介绍其工程应用及应用前景，并对现存问题进行讨论。     

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.     

Heating performance enhancement of a CO2 heat pump system recovering stack exhaust thermal energy in fuel cell vehicles

A CO₂ heat pump system using recovered heat from the stack coolant was provided for use in fuel cell vehicles, where the high temperature heat source like in internal combustion engine vehicles is not available. The refrigerant loop consists of an electric drive compressor, a cabin heater, an outdoor evaporator, an internal heat exchanger, an expansion valve and an accumulator. The performance characteristics of the heat pump system were investigated and analyzed by experiments. The results of heating experiments were discussed for the purpose of the development and efficiency improvement of a CO₂ heat pump system, when recovering stack exhaust heat in fuel cell vehicles. A heater core using stack coolant was placed upstream of a cabin heater to preheat incoming air to the cabin heater. The performance of the heat pump system with heater core was compared with that of the conventional heating system with heater core and that of the heat pump system without heater core, and the heat pump system with heater core showed the best performance of the selected heating systems. Furthermore, the coolant to air heat pump system with heater core showed a significantly better performance than the air to air heat pump system with heater core.     

PEM fuel cell stack sealing using silicone elastomers

The economic viabilty of proton-exchange membrane (PEM) fuel cells requires significant reductions in the cost of assembling and sealing the PEM stack. In addition, the stack sealing system or method must last the life of the stack, and is often used to enhance the structural strength of the stack and provide performance-enhancing functionality. This article discusses the findings and results of studies that are part of Dow Corning's PEM fuel cell stack sealing programme.     

两种不同形式蒸发冷却房间空调器的性能测试

分别选择直接式和间接式蒸发冷却房间空调器进行性能测试，并进行比较，指出直接式和间接式各自特点。在此基础上提出并论证将直接式和间接式结合起来的二级蒸发冷却用于房间空调器的可行性和优越性。     

Performance evaluation of a two-stage CO2 cycle with gas injection in the cooling mode operation

The cooling performance and reliability of a transcritical CO₂ cycle can be significantly improved by using a multi-stage compressor with gas injection because the CO₂ cycle has a large pressure difference across a compressor. The objective of this study is to investigate the performance and operating characteristics of a two-stage CO₂ cycle with gas injection. In this study, the performances of a two-stage CO₂ cycle with gas injection (called as “two-stage gas injection cycle”) were measured as the amount of refrigerant charge, first- and second-stage compressor frequencies, and first- and second-stage EEV openings were varied in the cooling mode operation. The cooling COP of the two-stage gas injection cycle was maximally enhanced by 16.5% over that of the two-stage non-injection cycle in the experiments. In addition, when the first- and second-stage EEV openings were increased, the compression ratio decreased and this in turn, improved the cooling COP of the two-stage gas injection cycle. However, when the first-stage EEV opening was increased, the mass flow rate through the evaporator decreased, and this in turn, decreased the cooling capacity of the two-stage gas injection cycle. Therefore, in the two-stage gas injection cycle, an optimum control of both EEV openings is required.     

单元式空调机冷却除湿技术分析

系统地介绍广泛应用于单元式空调机的冷却除湿技术。根据冷凝盘管再热技术在单元式空调机应用方式的不同,归纳4种代表性的方案,并分析每种方案的性能和成本。最后针对这几种不同的设计方案及应用,分别提出不同的技术设计要点和注意事项。     

Performance characteristics of a combined air conditioner and refrigerator system interconnected via an intercooler

Convenience stores and supermarkets are equipped with air conditioner and refrigeration/freezer systems that are independently operated; these systems consume approximately 50%–60% of the total electric power used by the convenience store or supermarket. In this study, a combined system that can recover the condensation heat of the refrigeration system into the air conditioner using an intercooler is developed. Experimental investigations are conducted in order to investigate the performance characteristics of the combined system. Then, the proposed combined system is installed in a convenience store and operated for one year in order to measure the annual power consumption in a real environment. The proposed combined system exhibits an increase in the operation ratio, a reduction in defrosting operations, and a 32% reduction in the annual electric power consumption. The intercooler contributes to the reduction in power consumption, as does the use of a variable speed compressor. It is also found that the flow rate of the intercooler should be optimized when the air conditioning system is operated in the cooling mode.     

采用微通道换热器的热泵型空调器性能研究

基于对采用自行研制的微通道换热器的热泵型空调器的实测结果,计算分析采用微通道换热器的热泵型空调器的能效提升效果。结果表明,在保持换热面积一定的情况下,采用微通道换热器可以使热泵型空调器的制冷和制热的能效提高20％以上。     

Performance optimization of a transcritical CO2 refrigeration system using a controlled ejector

An on-line optimal quasi cascade controller for an ejector with variable nozzle throat area is proposed to improve the operating performance of the transcritical CO₂ ejector refrigeration system. The optimal gas cooler pressure is tracked in real time by the controller including a tracker and a predictor. Using the system dynamic model, the dynamic responses of the system performance and ejector efficiency under variable nozzle throat area are first analyzed. Then the parameters of the tracker and predictor are determined by simulation respectively which exhibits a good dynamic characteristic with an acceptable settling time. Besides, the controller presents a good robustness under variable compressor speeds and mass flow rate of cooling water. Furthermore, the system performance is actually increased to the maximal value by the controller even at the variable operating conditions. Finally, the optimal controller is verified by experiments to be an effective way to improve the system performance automatically.     

Performance evaluation of a vapor injection heat pump system for electric vehicles

Battery-powered electric vehicles (EV) need an efficient electric heating system for extending the driving mileage. An air-source heat pump system offers an economical alternative for EV because it consumes less energy than a heating system using Joule heat and it can use the same components as an air conditioning system for cooling. However, its performance degradation is inevitable at very low ambient temperatures. Although vapor refrigerant injection is known as a good technology to overcome this problem in residential heat pump systems, the number of vapor injection heat pump studies for EV applications is quite limited. In this paper, considering the characteristics of EV application, the configuration of a vapor injection heat pump system for EV is introduced, and it was modeled, using a scroll compressor geometry-based thermodynamic analysis. The performance was estimated for cold ambient regions under the EV operational conditions.     

冷热联合储能式电动汽车空调系统的设计与经济性分析

介绍冷热联合储能式电动汽车空调的概念,对其储能性能进行分析,提出2种系统设计方案并进行比较。以S公司的一款电动汽车为例进行经济性对比分析,得出采用冷热联合储能式可以节约汽车制造成本20%以上或者增加30%左右的行驶距离。最后对制冷和制热运行模式进行优化,提出最大化利用储存冷热量的运行方案。     

燃料电池车用超高速空压机临界转速分析与提高措施

针对空压机进气增压可提高大功率燃料电池发动机性能和功率密度,但空压机超高速电机转子-轴承系统存在共振失稳乃至断轴的实际工程问题.本文采用有限元法建立空压机高速电机轴承-转子系统动力学模型,基于ANSYS软件对某超高速永磁电机转子进行动力学仿真,分析某燃料电池空压机高速电机转子-轴承系统的临界转速,揭示轴承刚度、轴承位置以及转轴质量等因素对临界转速的影响规律,并提出改善措施.结果显示,增大轴承刚度、适当减小轴承跨距以及减轻转轴的质量可以有效地增加转子轴承系统的临界转速.     

Mechanical design and analysis of a proton exchange membrane fuel cell stack

This paper presents a methodology to design, analyze, and improve the mechanical responses of a practical proton exchange membrane fuel cell (PEMFC) stack. Parametrical modelling, finite element analysis (FEA), and numerical optimization are implemented to study the PEMFC stack. Parametrical models are developed according to the actual product, and then can be applied for a structural analysis. A practical assembly is analyzed with FEA, and design defects due to the stacked cell-units and the clamping method are studied. Through solving the defects, the design criterions are proposed to improve the PEMFC stack. A clamping method is proposed to generate a uniform distribution of the clamping pressure. A ribbed endplate designed with the clamping method is optimized to decrease its weight.     

热回收型空调器的性能分析与实验研究

利用空调器本身的风机从热回收器内引进新风，通过热交换回收排风的能量。采用空气焓差法对空调器引进新风前后进行制冷量、输入功率、能效比（EER）等的对比实验，并测量了换热器的热回收效率。用热回收装置引进新风后基本没有改变空调器的输入功率，相同环境条件下的制冷量增加，EER值增大，焓差热回收效率最高可达到34．12％。     

Performance of a metal hydride cooling system

The performance of a single-stage metal hydride cooling system working with the ZrMnFe/MmNi_4.5Al_0.5 pair has been evaluated based on heat transfer and reaction kinetics considerations. Results show that the initial and operating costs of the system have to be minimized by optimizing the bed thickness, effective thermal conductivity and overall heat transfer coefficients. Of the three operating temperatures (heat source, heat sink and refrigeration temperatures), refrigeration temperature has the greatest influence on system performance, as desorption during the refrigeration process normally controls the cycle time and specific alloy output. However, heat source and heat rejection temperatures assume importance at high refrigeration temperatures. The average COP of the above system lies between 0.45 and 0.50.     

Energy and exergy comparison of a cascade air conditioning system using different cooling strategies

A cascade air conditioning system consisting of a compression and an absorption chiller working in a parallel arrangement has been proposed. This system is powered up by a micro-gas turbine. Different cooling strategies are studied in order to recognize the best configuration. The system components have been modeled and analyzed through the energy and exergy approaches. The performance parameters of the systems and the second law efficiency have been calculated in different operating conditions. Water consumption of the systems has also been investigated, considering water as a source of exergy. The results revealed that a system with water-cooled chillers has the highest second law efficiency and water consumption. On the other hand, the water consumption of a system with an air-cooled absorption and a water-cooled compression chiller is about 50% less than that of the system with two water-cooled chillers while its second law efficiency is only about 10% less.     

智能型变频热泵空调在北京轨道交通车辆上的应用研究

为验证变频热泵空调在北京地区轨道交通车辆上的舒适性和节能性,在制冷和制热工况下对北京燕房线车辆上变频热泵空调与单冷电加热型定速空调分别进行静态和运营试验对比。通过试验数据分析表明,相比于定速空调,变频热泵空调具有客室温度控制精度高,波动范围小,客室舒适性好,节能效果明显等优势,在北京地区轨道车辆具有良好的经济效益和应用前景。