近共沸混合制冷剂R134a／R600a／R600的应用研究

对于制冷剂R134a／R600a／R600组成的混合制冷剂，当其成分满足一定的要求时，可以形成一种近共沸混合物。本文介绍了这种近共沸混合制冷剂的性质，理论分析并实验验证了它作为R12的替代制冷剂的循环性能，并对它采用烷基苯或者矿物油作为润滑油时的制冷系统回油性能进行了实验研究。     

R513A替代R134a应用于螺杆式冷水(热泵)机组的试验研究

为验证R513A替代R134a应用于螺杆式冷水(热泵)机组的可行性,结合R513A制冷剂特性进行机组设计及系统匹配,并对R513A机组和R134a机组性能进行对比试验研究。结果表明,在相同工况下,R513A螺杆式冷水机组制冷量比R134a机组高2.3%,性能系数COP比R134a机组约低3.2%,综合部分负荷性能系数(IPLV)下降3.52%;而对于R513A螺杆式地源热泵机组,制冷量及热泵制热量均略高于R134a机组,全年综合性能系数(ACOP)值近似相等。由此可见,R513A可以作为R134a的替代制冷剂应用于螺杆式冷水(热泵)机组。     

冰箱中制冷剂R134a和碳氢化合物替代R12的研究

本文主要进行了冰箱中制冷剂替代物R134_a、R290、R600a与R12的分析比较,指出了其优缺点,并进行了理论计算,为冰箱中制冷剂替代物的选择提供了理论依据。     

R134a和R417A应用于热泵热水器灌注式替代R22的实验分析

在空气源热泵热水器中,对R22、R417A和R134a进行了理论计算及实验分析.结果表明,R417A的制热量和COP更接近于R22,并且排气温度比R22低25℃左右,排气压力也比R22平均低0.17MPa;尽管R134a也具有较低的排气温度和排气压力,但其制热量远远小于R22,低温工况下,吸气压力过低,而且需更换压缩机润滑油,因此,R417A比R134a更适合在空气源热泵热水器中对R22进行直接灌注式替代.     

船用冷藏装置以R134a替代R12作为制冷剂的研究

本文对制冷装置中以R134a替代R12作为制冷剂的运行及需要解决的问题作了分析，通过计算，得出结论认为，在船用制冷装置中用R134a替代R12是可行的，并给出了替换过程中要采取的措施。     

R1234yf热泵技术综述与潜力分析

为了满足逐步严苛的环保法规要求,R1234yf成为车用热泵制冷剂R134a的热门替代制冷剂之一。本文对R1234yf热泵技术的研究进行了综述与分析,其GWP<1,各方面性质均符合车用热泵系统的工作需求。在传热效果上,R1234yf的沸腾传热性能略优于R134a,且冷凝过程压降比R134a低5%~10%,优于R134a系统。在诸多R1234yf和R134a系统的仿真和实验研究中,R1234yf热泵性能略低于R134a,但可以通过优化零部件、强化补气、改善工况等方式使其与R134a十分接近甚至超越。R1234yf低压饱和压力比R134a高约15%,可以适配更高的压缩机转速,低温下制热性能比R134a更好,且较低的压缩机排气温度使系统工作更为稳定,强化补气的效果也优于R134a。因此,R1234yf在车用热泵中具有较好的工作性能和发展前景,可以作为R134a的替代制冷剂。     

R744/R600及R744/R600a混合工质热泵循环性能研究

基于换热器中的传热窄点温差的限制,对R744/R600及R744/R600a在所研究的工况范围内分别替代传统制冷剂R22的亚临界热泵循环特性分别进行了计算分析.结果表明:R744/R600和R744/R600a具有不同的最优配比,可以使得制热性能系数(COPh)最大;R744/R600及R744/R600a在最优配比下的COPh分别比R22系统增大11.98％和8.24％,分别比纯质R600和R600a大36.43％和36.24％,比跨临界循环R744系统增加7.07％和4.71％.在最优配比下,R744/R600和R744/R600a的冷凝压力低于R22,分别为0.84MPa和1.18MPa;压缩机排气温度也低于R22,在90℃以下.     

基于HFO的混合制冷剂R513A在螺杆式冷水机组中直接替代R134a制冷剂的试验研究

R513A是一款低GWP、非易燃、基于R1234yf的新一代制冷剂,其物性参数与R134a接近。因此,本文选择R513A作为原R134a螺杆式冷水机组的替代制冷剂开展试验研究。依据GB/T 18430. 1中规定的各试验工况,针对直接充注R513A和R134a的机组性能开展试验测试。对比研究了R134a和R513A在螺杆式冷水机组中的性能系数COP、制冷量、压缩机耗功并计算了两种制冷剂实际运行的综合部分负荷性能系数(IPLV)值。结果表明:在对原机组不做任何改动,采用R513A制冷剂的机组与原R134a机组相比运行性能参数相近,机组运行COP略有下降,IPLV值略有降低;在大跨度制冷负荷范围内运行时,部分工况点运行时,需针对原冷水机组的部分相关运行设定或机组组件做出相应调整。     

混合制冷剂R1234yf/R134a PVTx性质的实验研究

为了获得混合制冷剂R1234yf/R134a的热物性数据,本文利用Burnett法为基础搭建的高精度PVTx实验台,在温度为268~323 K时,测定了质量分数为55%/45%,50%/50%和45%/55%混合制冷剂R1234yf/R134a的PVT性质,最终拟合了三种不同配比的混合工质的气态维里方程,方程和实验数据具有较高的重合度。     

二甲醚作为中高温热泵工质的性能分析

对二甲醚（DME）作为中高温热泵工质的热工性能进行计算与分析,与传统热泵工质R22,R134a及自然工质R600a进行对比,并对变工况（冷凝温度75～95℃,固定循环温升45℃）进行理论计算。计算结果表明,DME制热性能参数与R134a接近,但COP值高于R134a,单位容积制热量在高温工况下具有更出色的性能。而且DME的GWP与ODP值均接近零,可作为绿色环保替代工质直接充注至R134a热泵系统,并可应用于中高温环境。     

R32/R134a和R407C用于变浓度热泵系统的实验

为了解决R32/R134a应用于变浓度热泵系统存在的排气温度过高问题,提出使用三元混合工质R407C用于该系统中.以R32/R134a和R407C作为工质在变浓度容量调节热泵系统中进行了吸气压力不变时的变浓度实验.实验结果表明,R407C在本系统中变浓度范围低于R32/R134a,但R407C的排气温度和耗功均低于R32/R134a,具有良好的变浓度调节潜力.     

R22替代工质回热循环的性能分析

R22的替代工质的制冷性能通常比R22差，采用回热循环是改善循环性能的一种方法，但是增加回热器会带来成本的增加，而且不同的制冷剂在回热循环中的COP及容积制冷量的变化也是不同的。针对上述问题，分析回热循环的特性和6种制冷剂（R290，R1270，R134a／R1270（0．45／0．55），R134a／R290（0．6／0．4），R407C和R410A）在回热循环中的容积制冷量和COP的变化特点。研究结果表明，R134a,／R1270，R290和R134a／R290系统使用回热器后，性能改善较大，R410A系统只有在高冷凝温度、高过热度时才有必要使用回热器，其余替代工质系统使用回热器，其系统性能改善不明显。     

Investigation of the heat pump water heater using economizer vapor injection system and mixture of R22/R600a

This paper presents the experimental study of a heat pump water heater (HPWH) using economizer vapor injection system and mixture of R22/R600a. Performances of HPWH using economizer vapor injection system are compared with that at different mixed mass ratios of R22/R600a. Study demonstrates that the heating capacity and energy efficiency ratio (EER) of the unit increased, and the discharge temperature of compressor decreased when using vapor injection and mixing refrigerant of R22/R600a. It is also found that the HPWH unit with economizer vapor injection system has a better performance for the high outlet water temperature under lower temperature conditions at 15% mass ratio of R600a for the mixing refrigerant. In addition, fundamental and practical influence of vapor injection pressure on the HPWH performance has been investigated experimentally. The simplified model is proposed for predicting the optimal vapor injection pressure of compressor using the mixing refrigerant R22/R600a.     

冷藏车层叠式蒸发器应用R404A与R22和R134a的比较

采用分布参数法对层叠式蒸发器建立数学模型，并对蒸发器采用R404A，R22和R134a时的换热和流动性能进行模拟比较。结果表明，在空调工况范围内，新型中低温混合制冷剂R404A具有R134a换热性能好和R22压降小的特点，能够很好地适用于冷藏车系统空调侧层叠式蒸发器。     

风冷螺杆热泵机组制冷剂替换试验研究

对R22、R407c、R134a三种制冷剂的基本物性及热力性能进行了分析比较，并在风冷螺杆热泵机组基础上进行了替换试验研究。结果表明：R407c为最佳替换R22的制冷剂；R134a替换后能效比较高，但制冷（热）量衰减过多，同时R134a的运行压力过低不太适合热泵工况。     

Performance comparison between a single-stage and a cascade multi-functional heat pump for both air heating and hot water supply

Multi heat pumps have been widely used in buildings due to their higher energy efficiency. Recently, demands for multi-functional heat pumps, which can provide heating, cooling, and water heating in a building, have been increased. In this study, a cascade multi-functional heat pump, combining a multi heat pump using R410A for air heating with a water heating unit using R134a for hot water supply, was investigated experimentally. The performance of the cascade multi-functional heat pump was measured by varying the refrigerant charge amount, EEV opening, water flow rate, and water inlet temperature. Test results were compared with those of a single-stage multi-functional heat pump using R410A for air and water heating. The cascade multi-functional heat pump adopting the water heating unit showed more stable air and water heating operations and higher water outlet temperatures than the single-stage multi-functional heat pump.     

Performance characteristics of a small-capacity directly cooled refrigerator using R290/R600a (55/45)

In this study, the performance of a small-capacity directly cooled refrigerator was evaluated by using the mixture of R290 and R600a with mass fraction of 55:45 as an alternative to R134a. The compressor displacement volume of the alternative system with R290/R600a (55/45) was modified from that of the original system with R134a to match the refrigeration capacity. Both systems with R290/R600a (55/45) and R134a were tested, and then optimized by varying the refrigerant charge and capillary tube length under experimental conditions for both the pull-down test and the power consumption test. The refrigerant charge of the optimized R290/R600a system was approximately 50% of that of the optimized R134a system. The capillary tube lengths for each evaporator in the optimized R290/R600a system were 500 mm longer than those in the optimized R134a system. The power consumption of the optimized R134a system was 12.3% higher than that of the optimized R290/R600a system. The cooling speed of the optimized R290/R600a (55/45) system at the in-case setting temperature of −15 °C was improved by 28.8% over that of the optimized R134a system.