Investigation on the Influence of Refrigerant Charge Amount on the Cooling Performance of Air Conditioning Heat Pump System for Electric Vehicles

The application of air conditioning heat pump(ACHP) in electric vehicles could lead to significant electrical power saving effect. As for an air conditioning heat pump system for electric vehicles, the influence of refrigerant charge amount should be investigated during the design phase. In this study, experimental method was employed to investigate the influence of the refrigerant charge amount on the performance of the ACHP system. The results showed that the refrigerant charge amount had different influence on the refrigerant properties at various locations within the system. The coefficient of performance and pressure-enthalpy diagram were calculated, and showed a close relationship with refrigerant charge amount under different compressor speeds. The degree of subcooling and the degree of superheating were recorded and the critical charge amount was determined by a typical practical test method. In addition, the critical refrigerant charge amount determined by the experimental method was also compared with two typical void fraction correlation models, and the model with consideration of two phase stream reaction of the refrigerant showed a good estimation accuracy on the critical charge amount.

Exergy Analysis of Electric Vehicle Heat Pump Air Conditioning System with Battery Thermal Management System

The exergy analysis of an electric vehicle heat pump air conditioning system(HPACS) with battery thermal management system was carried out by studying the exergy loss of each component. The results indicate that the compressor is the main source of system exergy loss in all operation conditions. The exergy loss distribution of HPACS is almost the same when the battery thermal management system integrated into the HPACS in cabin and battery mixed cooling mode and the system exergy loss was linearly related to the compressor speed in cooling modes. The performance of the HPACS is better than that of the positive temperature coefficient(PTC) heater in cabin heating mode. The degree of exergy efficiency improvement of the alternative mode was discussed at all operation conditions in cabin heating mode. The results indicate that the optimization effect using the electric vehicle HPACS to replace the PTC heater is obvious at lower compressor speed, surrounding temperature and internal condenser air flow rate.

Experiment Investigation and Control Strategies on Two-Phase Refrigerant Injection Heat Pump System for Electric Vehicle in Start-up Stage

Due to the poor heating performance and operating safety in low ambient temperature,traditional Air Source Heat Pump(ASHP)for Electric Vehicles(EVs)has many limits in cold region,which can be solved by the ASHP with refrigerant injection.During the start-up stage of EV in winter,the inlet air temperature of the in-car condenser is the same as the ambient temperature.At this situation,the performance and control strategy of the heat pump require special attention.In the present study,a series of experiments were carried out on the heating performance of the Refrigerant Injection Heat Pump(RIHP)system in start-up stage of EV,at the ambient temperature from–20℃ to–5℃.The effects of compressor speed and injected refrigerant state on the heating performance of the system were discussed in depth.According to the results,the control strategies during start-up stage have been discussed in the end of the article.The study provides a practical control strategy for the RIHP system during the start-up stage of electric vehicles,helping to efficiently operate electric vehicles in cold regions.

Simulation of Air Source Heat Pump with Refrigerant Injection for Heating Operation

An air source heat pump(ASHP)with refrigerant injection is proposed for the air conditioning system of electric vehicles(EVs),especially for efficient heating in cold winter,when there is no wasted heat of engines.The simulation model is built with the framework of two-phase fluid network,where the compressor is separated as two compressors and the economizer is treated as two heat exchangers in the injection path and the main refrigerant path.With the validated simulation model,the heating performance is analyzed,and the results show that the coefficient of performance(COP)of ASHP with refrigerant injection is higher than 1.4 and the discharge temperature is less than 100℃ when the outdoor temperature is-20℃.The above performance ensures that the air conditioning system and EVs can operate normally with high efficiency even in the cold winter,which is much helpful for the practicability of EVs.

基于蓄热装置辅助的燃料电池电动车供暖系统动态仿真

为了辅助燃料电池车辆预热,提升燃料电池在低温下的冷启动速率以及降低电动车能耗,该文提出了一种基于热泵和蓄热装置联合的燃料电池电动车供暖方案,并开展了燃料电池车辆系统动态仿真研究,对比了有无蓄热装置辅助的系统对车辆运行过程的影响。结果表明:在寒冷运行环境下,蓄热装置可确保驾驶循环工况下循环冷却液热量来源的连续性,相较于无蓄热装置的热管理系统,热泵和蓄热联合供暖方案可使空调系统能耗下降26%;利用蓄热装置辅助的供暖系统能够改善燃料电池电动车的冬季冷启动特性,优化车辆电池系统的热管理。

-30至50℃车辆工况下CO_(2)喷射器的适应性研究

为推动喷射器回收膨胀功技术的实车应用,本文开展了-30~50℃宽温区运行工况下车用压缩-引射式CO_(2)热泵系统制冷制热性能及喷射器膨胀功回收特性研究,重点分析了工作喷嘴对固定尺寸喷射器变工况适应性的影响。结果表明:制冷工况下随着环境温度升高,喷射系数递减,而升压比递增;制热工况下随着环境温度降低,喷射系数和升压比均先增大后减小;制冷工况下喷射器回收膨胀功占最大可回收膨胀功的16.7%~37.2%,制热工况下为9.9%~41.3%;以高温制冷工况设计的固定尺寸喷射器难以适应低温制热工况,偏离设计工况时,喷嘴出口过膨胀会造成激波能量损失,而低温制热工况下喷嘴出口因欠膨胀会导致喷射器无引射效果。

基于主动进气格栅的热泵空调系统能耗控制策略

为了降低热泵空调系统的能耗,针对车速、进气格栅开口面积等不同参数,以匹配主动进气格栅(AGS)电动汽车的热泵空调系统为研究对象,开发了一种热泵空调热管理系统及能耗控制策略,仿真计算高、低温环境和不同AGS开度条件下的系统能耗,并采用实车环境舱标定方法分析了-7℃低温和35℃高温环境不同AGS开度下空调系统及风阻能耗实测值差异。试验结果表明:高温和低温环境下,AGS开度越大,风阻能耗越高,但空调与风阻综合能耗越低;AGS开度增大相同数值时,高温条件下的能耗贡献量大于低温条件下的能耗贡献量。

某型纯电动汽车热泵空调系统探析——执行器篇

世界各国都在积极稳妥地推进“碳达峰“和”碳中和”进程,人们对选择绿色出行的认同感、获得感和幸福感日益增强,让新能源汽车行业发展的浪潮迅速席卷全球。搭载热泵空调的新能源汽车,以其能耗更低、高压蓄电池循环里程更长等优点已在汽车领域实现快速的推广。因此,本文以某型纯电动汽车热泵空调为例,结合汽车行业相关岗位需求,详细介绍热泵空调系统中相关执行器结构与工作原理。

某型纯电动汽车热泵空调系统探析-传感器篇

汽车空调能够调整和控制车内温度、湿度、空气清洁度及流向处于最佳状态,为驾乘人员提供舒适、清新的乘坐环境,有助于车内成员减少旅途疲劳和确保行车安全。在传统汽车空调基础上升级改进的热泵空调,还具备高环保、低价、高制热能效的特点,使其在新能源汽车领域的应用日益广泛,但在结构、工作模式等方面,与传统汽车空调系统有较大区别。因此,本文以某型纯电动汽车热泵空调为例,结合汽车行业相关岗位需求,详细介绍热泵空调系统的组成部件及基本工作原理。

热泵空调系统对纯电动汽车采暖性能影响的试验研究

采暖装置的能耗对纯电动汽车的续驶里程产生重要影响。为解决采暖高能耗问题,热效率较高的热泵空调系统逐渐代替正温度系数(PTC)材料作为纯电动汽车的采暖装置。文章通过基于整车层面的对比试验研究,测试二者在不同温度工况下的采暖效果和功耗,分析热泵空调系统的代替效果。试验结果表明,在温度较高的工况下,热泵空调系统采暖效果与PTC接近并且能耗显著降低;在温度较低的工况下,热泵空调系统的采暖效果弱于PTC,同时节能效果对比PTC优势缩小。试验结果为热泵空调的选配和改进研究提供一定的参考。

纯电动汽车热泵空调中热气与电热复合除霜方法的应用

纯电动汽车热泵空调在冬季制热时,室外换热器易结霜。为保障热泵空调在不影响车辆性能及舒适度的前提下正常运行,文章提出了复合除霜系统的设计:初期利用热气旁通法除霜,压缩机蓄热不足时,切换至电热除霜模式,同时考虑回收电动机废热用于电热除霜。确定系统参数后,使用AMESim软件进行了空调建模和分析,确定了旁通阀的最佳开度和除霜模式切换条件。

某纯电动车型的余热热源与空气源热泵控制策略研究

随着纯电动汽车市场的进一步拓展,为了满足北方客户在寒冷天气下的采暖需求,并缓解低温环境下纯电动汽车续驶里程的衰减,需要对纯电动汽车在低温下的整车热管理控制策略进行更加贴合使用场景的优化。通过针对某纯电动车型在低温环境下不同使用场景中余热热泵与空气源热泵热管理控制策略的研究与实车验证,将热泵热管理系统的有效使用环境温度下限从-15℃拓展到了-20℃,并且实现了该车型在-7℃低温环境下CLTC工况续驶里程衰减率达到31.2%的优秀水平。

直接热泵的出风温度裂隙和优化研究

采用直接热泵技术可以提升电动汽车的电能利用效能和综合热管理水平。但在春秋季等需要采暖、除湿的工况下,由于直接热泵的蒸发器和内置冷凝器的热量耦合在理论上可能会出现出风温度不连续的问题,即“出风温度裂隙”。文章研究了一种典型的直接热泵系统,在焓差实验室测试了10~30℃春秋季工况下出风温度的上下边界,确认了出风温度裂隙的存在。通过分析环境温度、压缩机性能、前端进风风量、空调箱进风温度等因素,提出了一系列优化对策,并进行了有效性验证,为解决直接热泵的出风温度裂隙提供了可能的解决方案。

采用水冷冷凝器的电动汽车热泵系统制热和抗结霜性能试验研究

热泵技术由于具有比电加热显著提升的制热效率,近年来逐渐应用于电动汽车以期提高冬季续航里程。文章设计了一套电动汽车热泵系统,该系统取消了传统热泵的车外冷凝器,而以低温散热器作为主要的散热和吸热部件。根据实车的零部件部件要求搭建了该热泵系统的测试台架,台架试验结果表明该热泵系统在-7℃环境下,纯热泵工况下的制热能力可以达到5.4kW,COP可以达到2.4。通过模拟电机电控的余热回收效果,试验发现低于30%的余热可以被该系统吸收用于制热。试验也表明这种类型的热泵系统在湿度较高的情况下同样存在结霜的问题,且结霜开始的时间与环境湿度和压缩机转速关系紧密。

热管理系统多通电子水阀的密封研究

为了降低新能源汽车热管理系统多通电子水阀内部泄漏量,分析泄漏产生原因,通过模拟仿真分析和实物样件试验测量,研究密封结构对泄漏量的影响。结果表明,通过优化阀芯、阀体、密封垫的结构设计,增加密封垫的压缩量,提高零件尺寸精度减小变形可以大幅降低阀的内部泄漏量,减少各通道之间串液和热交换,从而减少能量损失,对于提高热管理系统的能量利用率降低新能源汽车能耗有非常大的贡献。

Policies and Initiatives for Carbon Neutrality in Nordic Heating and Transport Systems

Policies and initiatives promoting carbon neutrality in the Nordic heating and transport systems are presented. The focus within heating systems is the promotion of HPs （heat pumps） while the focus within transport systems is initiatives regarding EVs （electric vehicles）. It is found that the conversion to HPs in the Nordic region relies on both private economic and national economic incentives. Initiatives toward carbon neutrality in the transport system are mostly concentrated on research, development and demonstration for deployment of a large number of EVs. All Nordic countries have plans for the future heating and transport systems with the ambition of realizing carbon neutrality.

流程布置对电动汽车热泵车外换热器性能的影响

针对电动汽车热泵用平行流车外换热器,通过建立基于制冷剂不均匀分配的分布参数模型,发现单流程和四流程结构的冬夏总体性能较差。单流程布置与二流程布置相比,夏季工况和冬季湿工况的换热能力分别下降25.3%和23.3%,四流程、三流程和二流程布置的换热能力差别不大。四流程布置和三流程布置的制冷剂侧压降分别是二流程布置的2.5~2.8和1.8~2.5倍。系统试验结果表明:在冬夏各工况下,二流程换热器系统的性能系数COP均高于三流程换热器系统,其中在冬季湿工况下,二流程换热器系统的制热量和COP较三流程换热器系统分别提高6.4%和9.4%。与三流程结构相比,二流程结构更适合电动汽车热泵的车外换热器。

电动汽车热泵空调系统冬季运行策略研究

随着气候变化等环境问题日益严峻,电动汽车替代传统燃油汽车正逐渐成为汽车行业的重要发展方向。针对电动汽车热泵空调系统冬季运行能耗高导致的续航里程大幅衰减问题,本文建立了电动汽车热泵空调系统数学模型,定量分析了不同舱外环境工况下采用不同空气循环模式时热泵系统的运行特性,结果表明:在寒冷地区典型冬季工况下,采用舱外空气循环的运行能耗较舱内空气循环高34.4%,而在夏热冬暖地区典型冬季工况下,采用舱外空气循环比舱内空气循环节能17.1%。在满足轿舱温、湿度需求的前提下,根据舱外环境工况合理选择空气循环模式可有效降低热泵系统的运行能耗,据此提出了基于舱外空气焓湿图分区的电动汽车热泵空调系统冬季运行策略,并给出不同气候区、不同乘员数条件下的节能运行模式。

电动汽车CO_(2)热泵空调制热性能分析

为提升电动汽车CO_(2)热泵空调的系统性能及扩宽热泵空调的使用温区,构建了回热器+补气增焓的跨临界CO_(2)系统,通过建立数值模型对该系统的制热性能进行了仿真分析。研究结果表明,气体冷却器压力对制冷系数(Coefficient of Performance,COP)影响较大,且存在最优气体冷却器压力和中间补气压力使COP达到最大值;中间补气过程能有效提升COP和制热量,且能有效降低压缩机排气温度;回热器过热度对COP和制热量影响较小,但会导致压缩机排气温度上升。