制冷剂R32特性及其用于空气源热泵热水器的理论循环分析

介绍R32,R22和R407C以及R410A四种制冷剂的流动特性和热力学特性,并对采用这4种制冷剂的空气源热泵热水器进行理论循环分析。从计算结果可以看出,与采用其他3种制冷剂的系统对比,采用R32制冷剂的系统具有较低的压缩比,较高的理论COP以及容积制热量;在当前阶段,R32是用于空气源热泵热水器的一种较好的制冷剂。     

R32空气源热泵热水器的实验研究

为了解 R32 和 R410A 制冷剂应用于空气源热泵热水器时的性能优劣,采用同轴套管换热器与空调室外机组相匹配,使用电子膨胀阀作为节流装置,在国标GB/T 23137-2008 规定下实验测试 R32 和R410A 在同一套空气源一次加热式热泵热水器样机上的性能.实验结果表明,R32 的充注量仅为 R410A 充注量的74%左右;在各种实验条件下,R32 空气源热泵热水器的能效比不低于 R410A 系统;在3℃低温环境下,R32 样机的性能系数提高31.1%,但排气温度达到101.9℃.不利于 R32 制冷剂在低温条件下的应用;因容积制热量较大,在相同设计能力下 R32 压缩机的排气量可以比 R410A 系统降低4.5%.     

常规空调热泵系统的R32替代研究述评

R32由于具有ODP为零、GWP值小于R410A等优越的环境性能,逐渐被认识到可以用于替代R410A。这里对R410A和R32的循环性能、润滑油的选用、可燃性、充注量、换热器性能等相关问题进行了综述。大量研究表明,与R410A系统相比,R32系统的压缩机耗功略高,制冷量较高,同时排气温度也高出很多,具有极大的替代R410A的潜力。然而,相关研究也指出要使其能够在大范围推广使用,除了要有效解决排气温度过高的问题之外,还需要解决其微可燃性在设计应用中所受到的限制。通过解读国内外法规政策发现,国内外对R32的充注量限制有放宽的趋势,这对R32在常规空调热泵系统中替代R410A和R22的研究工作将是一个巨大的推动。     

地埋管换热器变热流工况下换热模型及其试验验证

在制冷空调产品及热泵热水机国家标准规定的名义工况下,比较CO2跨临界循环与R22,R410A和R404A单级蒸气压缩循环的理论循环效率。结果表明：在空调制冷名义工况下,R22理论循环效率最高,CO2的理论循环效率只有R22的50％～60％;在热泵热水机名义工况下,CO2的理论循环效率最高,可以达到R22的145％;CO2跨临界循环受冷却器压力及出口温度2个方面的影响,适当降低CO2冷却器出口温度可改善循环效率,应用CO2制冷剂需要通过改善循环和优化控制提高系统的能效。     

R32风冷冷（热）水机组低温制热性能探讨

普通热泵空调系统在超低温环境下制热衰量减大,难以满足中国北方冬季取暖需求,在一套普通R410A风冷冷（热）水机组上分别对喷液技术和EVI技术进行超低温环境测试对比。结果表明,喷液系统和EVI系统在低温和超低温下具有较好的制热量及制热能效的提升,并且可以解决普通热泵在超低温环境下的应用问题,同时R32的热物理性质与R410A基本相同,提出在低温风冷冷（热）水机组上使用R32替代R410A的设想。     

R32在家用空调器中的应用研究

对比R32与R410A的基本物性和热力循环性能,并在同一台家用定频热泵空调器上进行性能测试。相对于R410A,在给定工况下,R32的理论循环制冷量最大可提高15％,能效比最大提高6％,容积制冷量和容积制热量增加7％～8．9％。性能测试结果表明,R32系统的制冷剂充注量比R410A系统的减少24％,额定制冷能力和能效比比R410A系统分别提高8％和3．3％,额定制热能力和性能系数也高于R410A系统。理论热力循环分析及性能测试结果均表明,R32制冷性能相对R410A有较大幅度的提高,制热性能比R410A略高或相当,但R32系统的排气温度较高,比R410A系统高出11．5～25．7℃,恶劣工况下排气温度甚至能达到114．9℃。     

低温工况下空气源热泵热水器中R22与R417性能对比

在低温环境下,研究了R22与R417A对空气源热泵热水器的性能影响。得出了机组性能系数(COP)、制热量、排气压力、压缩机功率和水箱水温与加热时间的关系。     

R134a/R600a混合制冷剂应用于大型空气源热泵的性能研究

R134a作为当前主要的R22替代制冷剂,在应用于空气源冷水(热泵)机组,尤其是在热泵运行时会出现能效降低、容易结霜等问题。本研究尝试在R134a的大型螺杆式空气源热泵机组中混合少量R600a来改善机组性能。通过对混合制冷剂物性计算、理论循环性能计算和机组试验,表明添加R600a后的混合制冷剂能显著改善热泵机组的运行性能,并有效提高机组运行可靠性。同时,虽然R600a具有可燃性,但是对于运行时置于室外,介质为水且添加比例不高的空气源热泵机组,这是一个简单、安全、可行的改进方案。     

Two-stage heat pump system with vapor-injected scroll compressor using R410A as a refrigerant

Refrigerant vapor-injection technique has been well justified to improve the performance of systems in refrigeration applications. However, it has not received much attention for air conditioning applications, particularly for air conditioning in hot climates and for heat pumping in cold climates. In this study, the performance of an 11 kW R410A heat pump system with a two-stage vapor-injected scroll compressor was experimentally investigated. The vapor-injected scroll compressor was tested with the cycle options of both flash tank and internal heat exchanger configurations. A cooling capacity gain of around 14% with 4% COP improvement at the ambient temperature of 46.1 °C and about 30% heating capacity improvement with 20% COP gain at the ambient temperature of −17.8 °C were found for the vapor-injected R410A heat pump system as compared to the conventional system which has the same compressor displacement volume.     

采用R410A为制冷剂的小型风冷式冷水机组设计

以R410A为制冷剂设计的一套小型家用风冷冷水机组。标准工况下,该机组的设计制冷量和制热量分别为16.5kW和18.0kW。在系统热力计算的基础上,介绍了以R410A为制冷剂的小型家用风冷冷水机组设备选型过程,选用了制冷量和制热量分别为16.89kW和19kW的全封闭涡旋式压缩机、实际总管长144m和实际传热面积70.24m2的翅片管式换热器作风侧换热器,板间距为0.0032m、单片传热面积为0.12m2的板式换热器作水侧换热器,毛细管作节流装置等。     

Regenerated air cycle potentials in heat pump applications

Air (reversed Brayton) cycle has been utilized in the area of refrigeration and cryogenics for several decades, but its potentials in heat pump applications were longtime underestimated. In this paper, a thermodynamic model for the regenerated air heat pump cycle with practical compressor, expander and regenerated heat exchanger was developed. Based on the model, the relations between the system performance and the operating parameters were analyzed. The optimal heating COP (coefficient of performance) and the corresponding pressure ratio were derived. Then, air heat pump cycles (regenerated cycle and basic cycle) and vapor-compression heat pump cycles (CO₂ trans-critical cycle and R410A subcritical cycle) were numerically compared. The results indicated that the regenerated air heat pump cycle not only gets the heating capacity in line with the heating load under different operating conditions but also achieves higher COP over trans-critical CO₂ heat pump cycle in applications of large temperature difference.     

Water-side reversible CO2 heat pump for residential application

This paper presents the energy assessment of a water/water R744 chiller/heat pump, working according to a transcritical cycle, used for winter heating, summer cooling and tap water production. The different functions (heating, cooling, hot water) are managed water side. The analysis of the R744 chiller/heat pump is based on an original simplified method, which is able to predict the energy performance of the unit based only on its performance data at the nominal rating conditions. The method was validated against experimental data. A comparison with a state-of-the-art R410A unit is presented. The monthly analysis shows that the CO₂ unit is very efficient in hot water production, but penalised in heating and cooling service. The adoption of an ejector in place of the expansion valve makes the CO₂ system reach the same energy consumption as the R410A unit, despite the presence of the water loop only in the R744 lay-out.     

Performance improvement of air source heat pump using gas-injected rotary compressor through port on blade

Gas injection has been a crucial technology to avoid the serious degradation of air source heat pumps in low ambient temperature. A novel injection structure on the blade for rotary compressors has been put forward in previous research to overcome the drawback of traditional injection structures. Based on a verified numerical model, the thermodynamic performance of an air source heat pump with the new gas-injected rotary compressor is investigated. The results indicate that, compared to the air source heat pump with the regular single-stage rotary compressor, the proposed injection structure can enhance heating capacity and COP of the air source heat pump by 23.1–28.2% and 4.5–8.1%, respectively.     

翅片管换热器最佳回路长度的仿真计算

针对采用R410A的空气源热泵的室外侧换热器，采用稳态分布参数法，对其作为冷凝器和蒸发器使用时回路的最佳长度进行了计算机模拟，为采用新型环保制冷剂的换热器优化设计提供一定的参考。     

一种用于低温环境下新型空气源热泵循环研究

提出了一种在低温环境下能扩大制热能力空气源热泵装置,既可按传统单级空气源热泵方式运行,又可按复叠循环方式运行.在低温环境下对两种空气源热泵循环特性进行模拟比较.模拟结果表明,在环境温度很低条件下,该热泵仍可获得较大制热量和较高COP值,并具有较小压缩比和较低压缩机排气温度.热泵制热应在最佳节能控制条件下运行以实现最大限度节能.它为解决热泵的低温适用范围和低温条件下节能等问题提供了一条可取的途径.     

Drop-in replacement of R22 in heat pumps used for district heating — influence of equipment and property limitations

In Swedish district heating systems several large (25 MW) turbo-compressor driven heat pumps using R22 are installed. The only commercially available alternative is R134a, but its use could decrease the heating capacity by 35%. In this paper a method for finding the best working fluid for a specific heat pump plant is presented, and applied to a district heating plant. First, a screening is made among almost 2000 mixtures, using criteria such as condenser pressure, Mach number and temperature glide. Simulations of the plant are then made to investigate the change in heating capacity and COP when using a mixture instead of R134a. The results show that there are mixtures that can offer a substantially higher heating capacity than R134a, but there is a decrease in COP. The importance of considering the limiting parameters of the heat pump, such as maximum volume flow to each compressor stage and minimum evaporator pressure, is shown.     

R417A和R22用于空气源热泵热水器的试验研究

对R417A和R22用于空气源热泵热水器进行试验,并在不同进水温度下对吸排气压力、吸排气温度、消耗功率、制热功率、热效率等方面进行对比分析。结果表明,混合工质R417A用于热泵热水器时,排气压力、输入功率低于R22的,制热功率易受水温影响,制热量低于R22的,性能系数下降迅速,但平均性能系数比R22的略高。     

开式地表水源热泵在湖南某人工湖的应用研究

我国南方地区的地表水资源丰富,其中蕴藏着丰富的低位热能,适合于发展地表水源热泵。2004年,在湖南省湘潭市建成了利用湖水的开式地表水源热泵系统用于区域供冷供热。建造该系统前,采用简化模型对运行时的水温分布情况进行了模拟分析。对系统投入运行以来每日的进水温度进行了监测,对地表水源热泵和风冷热泵的COP进行了测试。测试结果表明,在相同的热汇／热源温度和供水温度下,地表水源热泵的COP比风冷热泵高0．4-0．9,该系统的COP值和运行稳定性均优于风冷热泵。     

R32用于单元式空调机的性能实验研究

对比分析R32,R410A和R22的基本物性参数,并在R410A单元式空调机上开展直接充注R32的替代试验,测试不同充注量下的制冷量、功率和COP变化趋势.结果表明,充注R32的机组存在性能最优点,在相对R41 OA充注量为60%时,机组的制冷量和COP达到最大,并均高于R410A机组的.     

Field test investigation of a double-stage coupled heat pumps heating system for cold regions

This paper reports a double-stage coupled heat pumps (DSCHP) heating system, which couples air source heat pump (ASHP) and water source heat pump (WSHP) together. The system is presented for the first time in open literature with the objective to improve the working condition and heating performance of the ASHP under cold environment. A practical project in Beijing firstly installed this system and field test has been performed for one month. The test results indicate that the DSCHP system can be smoothly and efficiently used for heating in cold regions. Compared with the traditional ASHP heating system, the operating characteristics of the DSCHP heating system are greatly improved, demonstrating that the system can offer considerable application potential in cold regions.