Performance of R290 and R1270 for R22 applications with evaporator and condenser temperature variation

In this study, therma l performance of two hydrocarbon refrigerants of R290 and R1270 was measured in an attempt to substitute R22. They wer tested in a heat pump bench tester of 1 ton capacity with a hermetic rotary compressor. Water and water/glycol mixture were employed as the secondary heat transfer fluids in the test bench. All tests were conducted under the same external conditions simulating three different air-conditioning and heat pumping conditions. Test results show that the coefficient of performance of these hydrocarbon refrigerants is up to 11.5% higher than that of R22 under all conditions. Refrigeration capacity of R290 is up to 8.2% lower than that of R22 under normal air-conditioning and heat pumping conditions. Under extremely cold temperature conditions, however, the capacity of R290 is 5% higher than that of R22. On the other hand, the capacity of R1270 is similar to that of R22 under all conditions. Compressor discharge temperatures of these hydrocarbons are reduced by 14–31°C as compared to R22. The amount of charge is reduced up to 58% as compared to R22. Overall, these hydrocarbons provide good performance with reasonable energy savings without any environmental problems and thus can be used as long-term alternatives for residential air-conditioning and heat pumping applications.     

R410a和R22平行流冷凝器变工况特性的比较

对比研究了分别采用R22及其替代工质R410a的平行流冷凝器在室外变工况下性能的同异。通过建立平行流冷凝器的稳态分布参数模型,仿真研究了不同冷凝温度下R410a和R22的变工况特性,并引入质能比的概念对这两种工质的单位换热量所需制冷剂质量的多少进行了比较。仿真结果是R410a和R22的换热量、制冷剂侧压降和制冷剂质量随工况和冷凝温度的改变具有的相似的变化趋势,且R410a具有较高的换热量和较低的压降;两者的质能比随进风温度和进风量的升高均呈基本一致的向上抛物线的变化趋势,且R410的质能比低于R22。可以得出R410a与R22具有相似的变工况特性,适合替代R22应用于采用平行流冷凝器的汽车空调。并且R410a在传热、流动性能和降低制冷剂充注量方面均优于R22。     

Performance of R170/R1270 mixture under air-conditioning and heat pumping conditions

In this study, the performance of R170/R1270 mixture was measured on a heat pump bench tester to substitute for R22. The tester was equipped with a hermetic compressor providing a nominal capacity of 3.5 kW. All tests were conducted under typical summer and winter conditions of 7/45°C and ?7/41°C in the evaporator and condenser, respectively. During the tests, the composition of R170 varied from 0 to 10% with an interval of 2% for the R170/R1270 mixture. Test results showed that the capacities of the R1270 and R170/R1270 mixtures were 3.2–10.0% and 4.2–20.4% higher than those of R22, respectively. The coefficient of performance (COP) of R1270 was 2.7–3.6% higher than that of R22. On the other hand, the COP of R170/R1270 mixture decreased at a constant rate as R170 was added to R1270. The COP of R170/R1270 mixture was similar to that of R22 at 2% R170 and then became lower than those of R22 as R170 increased. For the mixture, the compressor discharge temperature was 8–20°C lower than that of R22. The amount of charge was reduced up to 55% compared with R22. Overall, pure propylene and R170/R1270 mixtures are good long-term candidates from the viewpoint of energy efficiency and greenhouse warming to replace R22 in residential air-conditioners and heat pumps.     

Condensation heat transfer coefficients of HCFC22, R410A,R407C and HFC134a at various temperatures on a plain horizontal tube

In this study, external condensation heat transfer coefficients (HTCs) of HCFC22, R410A, R407C, and HFC134a were measured on a smooth horizontal tube at 30, 39, and 50°C with the wall subcooling of 3–8°C. The results showed that condensation HTCs decreased for all fluids tested with an increase in temperature. This is due mainly to such properties as the saturated liquid density and liquid thermal conductivity. These properties decrease as the temperature increase and accordingly HTCs decrease. The condensation HTCs of R410A are 9.2–19.7% higher than those of HCFC22 while those of R134a are 2.5–10.2% lower than those of HCFC22. Condensation HTCs of R407C, non-azeotropic mixture, are 29.4–34.3% lower than those of HCFC22. Overall, the HTCs of R407C are much lower than those of HCFC22, HFC134a and R410A due to the mass transfer resistance in a diffusion vapor film. Condensation HTCs of HCFC22 and HFC134a are higher than those calculated by Nusselt’s equation by 7.7–11.8% and 4.0–11.1% respectively. On the other hand, HTCs of R407C measured on plain tube, however, are not well predicted by these well-known prediction correlations due to the introduction of mass transfer resistance associated with non-azeotropic mixtures.     

不同制冷剂在空调冷凝器内换热性能的比较

通过建立空调换热器分布参数模型,并对模型进行了验证,进而对R22替代制冷剂R32、R410A、R407C和R290在翅片管冷凝器进行了研究,分析了不同迎面风温和风速下冷凝器的流动和传热规律。研究表明:在一定的条件下,无论增加迎面风温或风速,R407C单位面积换热量,压降和质量流量最大;R290和R32压降和循环质量流量均小于R22;R410A虽然压降较小,但循环流量大;R290循环质量流量较R22小40%左右,且R290换热温差较小,换热系数较高。     

部分负荷工况下螺杆制冷压缩机特性试验研究

研究了采用不同工质时螺杆制冷压缩机在部分负荷工况下的性能特性。通过录取半封闭螺杆压缩机工作过程指示图(p-V图),获得了部分负荷下螺杆制冷压缩机的效率及其变化规律,并根据部分负荷下压缩机内容积比的变化,对这种变化规律进行了解释。随后对螺杆压缩机采用R22、R134a、R404A、R407C四种不同工质时,在部分负荷工况下的性能变化规律进行了分析比较。研究结果表明：随着负荷的降低,压缩机的绝热效率和绝热指示效率都会有明显的下降,但机组系统的性能系数PCO会有明显的上升;使用R22工质时机组的使用部分负荷值VAPL为最佳。     

R407C房间空调器系统性能模拟与换热部件

对替代房间空调器用制冷剂R22的R407C工质的应用进行了研究,分别建立了空调器主要部件(蒸发器、冷凝器、压缩机、毛细管和连接管道)的分布参数模型(除压缩机模型外), 并对空调器进行了模拟.且就换热器的结构参数编制了优化模块,获得了一些有参考价值的研究结果.     

风冷冷热水机组R290替代R22的试验研究

分析了R290替代R22存在的优势,采用某企业生产的R22家用空调外机与套管换热器作为原型机,分别灌注R22和R290,灌注R290的同时更换大排量压缩机,调整节流装置最佳,优化灌注量,试验参照GB/T 18430.2—2008名义工况进行。结果表明:R290系统灌注量仅为R22的44.7%,制冷及制热名义工况下R290能力及能效比均不低于R22,但R290系统排气温度及压缩比明显低于R22。R290可以替代R22用于风冷冷热水机组,相应的压缩机排量应增加19%左右。     

非共沸混合制冷剂R407C替代技术的研究进展

介绍了制冷剂R22的替代工质R407C的研究现状，指出新工质的替代应以实验研究为主，并从安全性、热力学性能、传热性能及应用等方面进行综合考虑，使新工质能最大限度地适应现有的制冷空调系统。     

冬季工况下R32热泵性能的试验研究

以一台变转速热泵空调器为研究对象,测试其在冬季用R32做制冷剂时机组的能效及换热器的传热性能,以研究制热工况下空调系统中用R32作为替代制冷剂的可行性。试验测量参数包括蒸发器(室外机)和冷凝器(室内机)的传热系数、换热量、总压力降以及整机制热工况下的COP。通过结构匹配的室内、外侧两换热器在系统运行中同步测量,结果表明:冬季名义制热工况下,R32空调系统的制热能力比用R410A高出约3.0%,蒸发器、冷凝器的传热系数也有所提高,其中蒸发器的传热性能提高约6.0%,冷凝器传热性能提高约6.7%,而压降对比则变化不大。     

R290替换R22应用于家用空调的试验研究

分析了R290应用于家用空调的优势及可行性,采用某企业生产的R22家用冷风型分体机,直接充注R290制冷剂,在焓差实验室内调整毛细管规格及制冷剂灌注量,使性能达到最佳状态,结果表明:R22系统直接灌注R290制冷剂,灌注量仅为原来的44.7%,但制冷量下降13.64%,能效比稍有提高。为进一步减小灌注量、提高制冷量,采用了平行流换热器作为冷凝器,重新调整灌注量及毛细管规格,结果显示R290灌注量大幅减少,制冷量及能效比显著提高,R290灌注量的减少有利于制冷系统的安全性。     

R290家用空调的替代与应用研究

通过对R290与其它几种家用空调制冷剂的热力性能分析与比较，得出R290具有良好的热力性能，其物理性质与R22极其相近，属于直接替代物。开发R290家用空调，对环境保护、节约能源有着很好的应用前景。     

R404A在螺杆冷水机组中替代R22的性能试验研究

为研究HFCs非共沸混合制冷剂R404A(R125／R143a／R134a，44／52／4Wt％)替代R22的可行性和适用性，将：R404A充入LSLG16开启式螺杆冷水机组(原为R22)，并在不同工况下进行性能试验。试验结果表明，与R22螺杆冷水机组相比R404A机组的制冷量、消耗功率、冷凝器和蒸发器的传热系数均在不同程度上有所增加，COO略有下降。     

近共沸混合制冷剂R410A的研究进展

介绍了目前国内外对制冷空调系统替代制冷剂的有关研究，制冷剂R22的替代物R410A的安全环保性、热力学性能、蒸发冷凝换热特性、在节流元件中的性能以及对现用压缩机及润滑油的适应性等方面的研究现状。该工作对新工质R410A如何更好地适应现有的制冷空调系统很有意义。     

Cooling performance of R510A in domestic water purifiers

In this study, the performance of R170/R1270 mixture was measured on a heat pump bench tester to substitute for R22. The tester was equipped with a hermetic compressor providing a nominal capacity of 3.5 kW. All tests were conducted under typical summer and winter conditions of 7/45°C and −7/41°C in the evaporator and condenser, respectively. During the tests, the composition of R170 varied from 0 to 10% with an interval of 2% for the R170/R1270 mixture. Test results showed that the capacities of the R1270 and R170/R1270 mixtures were 3.2–10.0% and 4.2–20.4% higher than those of R22, respectively. The coefficient of performance (COP) of R1270 was 2.7–3.6% higher than that of R22. On the other hand, the COP of R170/R1270 mixture decreased at a constant rate as R170 was added to R1270. The COP of R170/R1270 mixture was similar to that of R22 at 2% R170 and then became lower than those of R22 as R170 increased. For the mixture, the compressor discharge temperature was 8–20°C lower than that of R22. The amount of charge was reduced up to 55% compared with R22. Overall, pure propylene and R170/R1270 mixtures are good long-term candidates from the viewpoint of energy efficiency and greenhouse warming to replace R22 in residential air-conditioners and heat pumps.     

R407C空调器系统及换热器的研究进展

随着R22替代期限的接近，替代制冷剂的研究更加紧迫,混合工质R407C各项性能与R22相当．可在系统稍做改变的前提下用于直接替代，这使得R407C的应用前景非常广泛，但R407C的COP略低于R22．这就需要加快对其换热器及系统的研究以提高其性能。     

替代工质R32和R290的对比研究

依据GB/T7725—2004规定的试验工况,分别对应用R32和R290的空调系统进行性能测试。在理论分析的基础上,依据试验数据,对比分析两种替代制冷剂的优缺点及其系统的改进方法。结果表明:R32单位容积制冷量高出R290约87%左右,相同制冷量下R290系统应使用更大排量的压缩机。R32具有较高的排气温度,并且R32系统相比R290系统,压比高出约7%,系统整体的能效比低约3.7%。R290系统换热器的压降要小于R32,有助于提高系统性能。但其可燃性远远大于R32,在安全设计方面有着更高的花费,系统初期改造投入比较高。     

培尔顿式膨胀-辅助压缩机在制冷系统中的研究

研究了一种具有简单结构的培尔顿式膨胀-辅压一体的能量回收装置,可用于小型制冷系统中取代节流阀,回收膨胀过程的压力损失,并将其直接转化为机械功作用于系统中,达到能量回收利用的目的.通过理论分析和模拟计算,比较了辅助压缩机在系统中的布置方式对回收功、制热量、COP等参数的影响,并对常用氟利昂工质R410A、R134a、R22的运行参数进行了比较.设计并制作了能量回收装置的样机,搭建了可供系统试验比较的测试台,讨论了部分试验结果及改进方向.     

R427a应用于空气源热泵热水器的性能研究

对制冷剂R427a在空气源热泵热水器上的应用做了研究,并与常用制冷剂R22和R134a在典型工况下做了对比分析,分析了3种制冷剂的吸排气压力、吸排气温度、压缩机功率、制热量、性能系数随环境工况变化的关系,得出了各特性参数的变化规律;另外在5℃进出水温差条件下,热水进水温度每上升5℃(如50℃进水,55℃进水,60℃进水)时,制热量下降2%～3%;COP下降10%～11%;功率上升11%～13%;吸排气压力分别上升3%～4%、10%～15%;吸排气温度分别上升5%、10%左右;这些为热泵热水器的设计使用及工质选用提供了参考。     

煤矿井下空调蒸发器对流传热特性试验

对恒定控制制冷剂R407C工作温度为9℃、额定制冷量为45k W条件下的蒸发器进行了模拟矿井条件湿空气的对流传热试验。研究结果表明:蒸发器的制冷量随进口空气温度的升高而增加,随进口空气相对湿度的增加而增加;出口空气温降随进口空气温度的升高而增加,随进口空气相对湿度的增加而缓慢降低;对流传热的Nu数随Re数的增加而增加,随进口空气相对湿度的增加而降低。