带经济器的热泵系统用涡旋压缩机的理论研究

通过对带经济器的涡旋热泵系统进行分析,建立了带经济器热泵系统用涡旋压缩机的数学模型,并根据这一模型的仿真结果分析了补气口位置对经济器系统性能的影响和补气口大小的确定方法,并给出了补气口起始的角度和补气口面积的计算式。仿真结果表明：对于实际涡旋压缩机,为了保证热泵系统在冬季低温工况下的制热性能以及夏季高温工况下的制冷性能最佳,并防止泄露,最佳开设角度可在靠近吸气腔刚刚闭合处的角度附近;设计压缩机补气口时,应考虑经济器热泵的使用环境,同时兼顾涡旋压缩机的结构特点以及加工方法等因素的限制,故应选取尽可能大的补气口,并开成圆孔。     

带经济器的热泵系统用涡旋压缩机的理论研究

通过对带经济器的涡旋热泵系统进行分析,建立了带经济器热泵系统用涡旋压缩机的数学模型;根据模型的仿真结果分析了补气口位置对经济器系统性能的影响和补气口大小的确定方法,并给出了补气口起始的角度和补气口面积的计算式。仿真结果表明：对于实际涡旋压缩机,为了保证热泵系统在冬季低温工况下的制热性能以及夏季高温工况下的制冷性能最佳,并防止泄露,最佳开设角度可在靠近吸气腔刚刚闭合处的角度附近;设计压缩机补气口时,应考虑经济器热泵的使用环境,同时兼顾涡旋压缩机的结构特点以及加工方法等因素的限制,故应选取尽可能大的补气口,并开成圆孔。     

经济器补气压力对双螺杆制冷压缩机性能影响的试验研究

在制冷系统中使用经济器提高了系统制冷量，但由于中间补气使压缩机耗功增加，制冷系统的COP并不会随制冷量成正比增长，其增长幅度依赖于补气压力、补气孔口位置等参数。通过实测补气工况下双螺杆制冷压缩机的P—V图，分析了不同补气压力下压缩机的热力过程特征，研究了补气压力对双螺杆制冷压缩机性能及COP的影响。研究结果表明：压缩机工作腔内气体压力在开始补气时会大幅上升，随后上升幅度逐渐变缓甚至略有下降，压缩机效率和系统COP随补气压力的上升出现先升后降的趋势，结果，存在一个最佳补气压力使制冷系统的COP增加幅度最大。     

变频螺杆压缩机经济器的变工况实验研究

为提高带经济器的变频螺杆压缩机效率,本文实验研究了压缩机排气压力、电机频率、经济器补气压力、容积效率等参数对压缩机效率的影响,得出压缩机排气压力和电机频率对经济器补气压力的变化规律。当冷凝温度为40℃,蒸发温度为5℃时,电机频率从200 Hz降至50 Hz,经济器补气压力上升了88.3 k Pa;当排气压力提高30%,经济器补气压力仅上升了4.9 k Pa,压缩机的容积效率仅降低约2%。结果表明:与压缩机排气压力相比,电机频率对补气压力和容积效率的影响较大。     

带闪蒸型经济器的风冷螺杆热泵机组性能的实验研究

研究了带闪蒸型经济器风冷螺杆热泵机组对制热性能的影响,理论分析了补气压力的变化对机组制热性能的影响。研究表明,带闪蒸型经济器热泵螺杆机组制热量随经济器的补气压力的减小而增大,压缩机功率也随经济器的补气压力的减小而增大,压缩机的COP随着经济器的补气压力的升高先升高再降低,存在最佳效率的补气压力点。实验测试了比最佳补气压力点偏高的经济器补气压力对机组性能的影响,理论计算结果和实测数据吻合良好。     

两次中间补气涡旋压缩机的工作特性

建立了涡旋压缩机两次中间补气制冷系统的计算模型,通过编制软件对系统的性能进行模拟研究。确定出开设两对补气孔时最佳补气压力的范围,归纳出最适宜的两次中间补气压力范围经验公式;针对某一款涡旋压缩机给出了补气孔的设计方法。最后,对系统的循环性能进行研究,结果表明:与中间补气系统和单级系统相比,两次中间补气系统的制冷COP分别提高2.8%和12.4%。排气温度降低3~4℃。     

电动汽车空调热泵型涡旋压缩机结构分析

为了解决电动汽车空调系统冬季采暖问题,针对冬季空调工况下压缩机单级压比增大的运行特性,以涡旋压缩机制热性能系数为热力学优化目标函数,确定了制冷剂循环系统中的最佳补气压力,优化了涡旋压缩机静涡旋盘上的中间补气口的几何位置和形状,使其具备了准双级压缩功能。将研发的热泵型电动涡旋压缩机安装于电动汽车空调系统,利用空气焓差法对系统进行了制热、制冷性能实验。实验结果表明,静涡旋盘结构优化后的热泵型电动涡旋压缩机,其制热和制冷能力可以满足5人座电动汽车司乘人员的冬季和夏季舒适性要求,并且具有较高的制热和制冷性能系数,从而提升了汽车空调系统热泵循环和制冷循环的热经济性,达到了节能的目的。     

R32经济器系统涡旋压缩机中间补气参数的分析与优化

为了优化带经济器的R32空气源热泵系统的制热性能,结合涡旋压缩机的结构以及实际运行特点,本文利用MATLAB建立了系统的数学模型,并通过实验数据验证了仿真结果,研究了在不同环境温度下系统的补气压力、准一级压缩内容积比对相对喷气量的影响。研究结果表明:经济器系统较普通热泵系统,更适宜在环境温度低于-10℃的工况下运行;R32经济器热泵系统制热模式的最佳结构和运行参数为:系统的准一级压缩内容积比为1.1时,压缩机的相对喷气量值最大;当环境温度低于-10℃时,最佳相对喷气量宜取为0.22~0.33;当环境温度为-10~-5℃时,最佳相对喷气量宜取0.20~0.22;当环境温度高于-5℃时,则宜为0.18~0.20。相应的最佳相对喷气压力在0.85~1.31之间,处在最佳补气参数范围内,经济器热泵系统的优势越明显。     

滚动转子式补气压缩机在热泵系统中的实验研究

介绍了滚动转子式补气压缩机的设计,并将其在热泵系统中进行了实验研究。分析了不同制热工况下滚动转子式补气压缩机的性能,对比了带闪发器与过冷器的经济器热泵系统、滚动转子式与涡旋式补气压缩机的性能。结果表明:随着室外环境温度的下降,滚动转子式补气压缩机补气后制热量提升比例逐步增大;滚动转子式补气压缩机制热实验中,带闪发器系统的制热量较高;在超低温制热工况下滚动转子式补气压缩机制热量提升18%左右,与涡旋式补气压缩机相比制热量相当,性能略高。     

带经济器涡旋压缩机系统的研究

涡旋压缩机在我国已经得到了广泛的应用,但其在冬季寒冷地区系统压缩机仍无法启动或制热量不足。本文对带经济器涡旋压缩机进行了实验研究,使问题得到了有效的解决。     

Investigation of R-744 Voorhees transcritical heat pump system

Using economizer in R-744 heat pump cycle is an effective way to improve the heating capacity in cold climates. In this paper, a modification construction of reciprocating compressor with economizer port, a Voorhees compressor was introduced and the heat pump cycle with Voorhees economizer was compared with the traditional screw or scroll economizer cycles. Both the R-744 transcritical heat pumps with and without Voorhees economizer were tested at the same conditions with different air mass flow rates and different evaporating temperatures. The results show that the heating capacity of the heat pump with Voorhees economizer can be two times higher than the transcritical heat pump without economizer at low evaporating temperature conditions. At the same capacity operation conditions, the efficiency of the heat pump with Voorhees economizer is higher at high refrigerant mass flow rate conditions. The optimum discharge pressure of the heat pump with Voorhees economizer is found to be higher than the heat pump without economizer at the same ambient conditions. For mobile heat pump application, CO₂ transcritical heat pump with Voorhees economizer demonstrates better performance comparing to the conventional transcritical CO₂ heat pump without economizer when the evaporating temperature is lower than −20 °C, or when the mobile is idling with low compressor RPM.     

低温空气源热泵技术的应用

介绍带经济器的低温空气源热泵技术,通过对低温空气源热泵机组与普通空气源热泵机组的制冷量、制热量和能效比等参数进行测试及对比,探讨低温空气源热泵技术的应用优势。试验结果表明:与普通机组相比,低温机组在名义制冷和名义制热工况下冷热量和能效均有所提升;在-10~-15℃的环境中,普通机组制热量严重衰减使其不适用于此温度区间,低温机组制热量虽然也在减少,但其COP仍可达2.0,且排气温度相对较低;在-15~-20℃超低温环境中,低温机组仍可稳定运行,且能效比在2.0左右。     

中间补气量对经济器热泵系统性能的影响

对带经济器的热泵系统进行了理论分析,建立了整个系统的数学模型,进行了实验研究,研究分析了低温工况下中间补气量对各系统性能的影响。结果表明：在低温环境下,系统的制热量、压缩机功率都会随中间补气量的增加而增加,排气温度随中间补气量的增加而显著减小,系统COP先增加后减小,根据实验结果可知最优的中间补气量,约占环境温度下系统总质量流量的10-14%。     

热管在热泵干燥器中应用的研究

依据质量平衡和能量平衡规律,建立了带热管回热器的热泵干燥器数学模型,该模型由热管,干燥室,蒸发器,压缩机和冷凝器五大模块组成,利用此模型对系统的性能参数及运行规律进行了模拟研究。同时,对模拟所得到的部分结果做了实验验证。     

火电厂烟气余热利用现状与展望

火电厂烟气余热深度利用可有效提高电厂的热经济性。对国内外几种余热利用方式进行了综述,包括常规余热利用方式和几种新型余热利用方案如换热器分级布置、旁路烟道技术和热泵技术等。对不同余热利用方式的节能效果进行了详尽对比分析,认为常规低温省煤器烟气余热利用方案回收的热量较为有限,分级余热利用可实现能量的梯级利用,旁路烟道技术排挤了更高级别抽汽而更具经济性,而热泵技术能进一步利用废热提升能量品质。     

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.     

A study on the performance of multi-stage heat pumps using mixturesEtude sur la performance de pompes à chaleur multi-étagées utilisant des mélanges

Multi-stage heat pumps composed of a condenser, evaporator, compressor, suction line heat exchanger, and low and/or high stage economizers are studied by computer simulation. Their thermodynamic performance and design options are examined for various working fluids. In the simulation, HCFC22/HCFC142b and HFC134a are studied as an interim and long term alternatives for CFC12 while HFC32/HFC134a and HFC125/HFC134a are studied as long term alternatives for HCFC22. The results indicate that the three-stage super heat pump with appropriate mixtures is up to 27.3% more energy efficient than the conventional single-stage system with pure fluids. While many factors contribute to the performance increase of a super heat pump, the most important factor is found to be the temperature matching between the secondary heat transfer fluid and refrigerant mixture, which is followed by the use of a low stage economizer and suction line heat exchanger. The contribution resulting from the use of a high stage economizer, however, is not significant. With the suction line heat exchanger, the system efficiency increases more with the fluids of larger molar liquid specific heats. From the view point of volumetric capacity and energy efficiency, a 40%HCFC22/60%HCFC142b mixture is proposed as an interim alternative for CFC12 while a 25%HFC32/75%HFC134a mixture is proposed as a long term alternative for HCFC22.     

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.     

Using an air cycle heat pump system with a turbocharger to supply heating for full electric vehicles

Air cycle heat pump has large potentials in heating applications. However, a key challenge faced nowadays is the matching problem between its expander and compressor. This paper presents the performance evaluation of an air cycle heat pump system integrated with a turbocharger, a blower and a regenerated heat exchanger. A thermodynamic model for this system is first developed and the relationships between the system performance and the operating parameters are investigated. Then, the performance of three different air cycle heat pumps with a blower installed before the compressor, and a blower installed before the turbine, and with an expander, are numerically simulated. The results indicated that the blower installed before the compressor can achieve a higher heating capacity and thus a higher COP. Finally, the heating power consumption of air cycle heat pump was compared with the PTC and the vapor compression heat pump of the full electric vehicle.