Performance Analysis of a Solar Continuous Adsorption Refrigeration System

A study is conducted on the performances of a solar powered continuous-adsorption refrigerator considering two particular days as references cases,namely,the summer solstice(June 21st)and the autumn equinox(September 21st).The cooling capacity,system performance coefficient and the daily rate of available cooling energy are assessed.The main goal is to compare the performances of a solar adsorption chiller equipped with a hot water tank(HWT)with an equivalent system relying on solar collectors with no heat storage module.The daily cooling rates for the solar refrigerator are found to be 102.4 kWh and 74.3 kWh,respectively,on June 21st and on September 21st,using a total collector’s area of 43.47 m2.The corresponding values for the adsorption chiller equipped with a hot water tank of 2 m3(and using a total collector’s area of 72.45 m2),are 127.1 kWh and 106.13 kWh,respectively.

Experimental Performance of Moderate and High Temperature Heat Pump Charged with Refrigerant Mixture BY-3

Theoretical and experimental analysis of a new refrigerant mixture BY-3 was conducted based on a single-stage vapor compression refrigeration system. The water-water heat pump system used BY-3 to produce hot water when the low temperature was 20 ℃. The following results were obtained: the highest temperature at the condenser outlet reached about 85 ℃; when the difference between the water temperatures at the condenser outlet and the evaporator inlet was less than 40 ℃, the coefficient of performance (COP) was larger than 4; when the difference reached 55 ℃, the COP still kept 3; the discharge temperature of BY-3 was lower than 100 ℃, and the refrigerant vapor pressure kept lower than 1.8 MPa. When the water temperature at the condenser outlet reached over 85 ℃, nearly a 5 ℃ superheating temperature was maintained.

热电制冷/热泵教学实验装置的研制

为了让学生掌握热电制冷的工作原理及研究应用,研制了热电制冷/热泵实验装置用于本科实验教学。该实验装置在能量利用方面可实现一系列能量的存储与转换;在制冷/供热形式方面可实现供冷(热)水及冷(热)风功能;在热端散热方式方面可实现自然对流散热、水冷散热及强制风冷散热或水冷加风冷组合散热模式。同时,该实验装置可进行现象演示及散热器端/散冷器端自然对流、强制对流热电性能、冷却水流量及输入电压对热电性能的影响和太阳能光伏发电系统对热电性能影响的研究。

采用非共沸制冷剂的双喷气增焓两级压缩热泵循环研究

提出一种采用非共沸制冷剂的双喷气增焓两级压缩热泵循环(DVIC),该循环在普通喷气增焓循环(VIC)的基础上采用分液冷凝技术,并增加一组闪蒸器,减少系统不可逆损失,改善热力性能。采用R290/R1336mzz(Z)非共沸制冷剂,对DVIC进行研究,并与VIC进行比较。结果表明:在设定工况下,DVIC比VIC拥有更优的循环性能,系统COP和(火用)效率分别提高5.82%和8.41%,压缩机功耗降低6.39%;在较低蒸发温度或较高冷凝温度的运行工况下,DVIC性能的改善效果更加明显。

Experimental research on the heating performance of a single cylinder refrigerant injection rotary compressor heat pump with flash tank

A single cylinder rotary compressor was applied in the refrigerant injection air-source heat pump to improve the heating performance in cold regions. In this study, the performance of an R410 A single cylinder rotary compressor vapor injection(SCRCVI) system was measured and analyzed by varying the compressor frequency f and injection pressure Pi njat the ambient temperature To d=–10°C.The experimental results indicated that an optimum injection pressure to gain the maximum COP_h (coefficient of performance) existed in the SCRCVI cycle. However, the maximum COP_h of the SCRCVI system decreased as the increase of the frequency, and the maximum COPhwas even lower than that of the CSVC system at high compressor frequency. Therefore, in view of the energy saving and emission reduction, the SCRCVI system should be switched to single stage compression system when the heating capacity demand could be satisfied at high compressor frequency f. Compared to the conventional single-stage vapor compression(CSVC) system, refrigerant injection could enhance the heating capacities and COP_h by 28.2% and 7.91%, respectively. The average total mass flow rate of the SCRCVI system was 24.68% higher than that of the CSVC system. As the SCRCVI system worked at the optimum injection pressure, the variation trends of the different system parameters were investigated in detail. These trends were reliably used to optimize the refrigerant injection system design and the control strategy. The parameter of(P_(inj)–P_s) could be adopted as the signals to control the opening of the upper stage electronic expansion valve EEV1.

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.

电动汽车CO_(2)热泵系统性能实验研究

本文以天然工质CO_(2)为制冷剂,提出了适用于跨临界区域的CO_(2)热泵系统,并对车辆进行道路测试,验证了CO_(2)热泵系统在不同低温环境(-15℃、-23℃)下空调的脚部出风温度、脚部温度均满足整车技术规范参考标准,且温差波动较小。当环境温度较低时,最大制热性能也相对较好,脚部出风温度平均增加了约2.96%。之后与传统制冷剂R134a热泵系统进行对比,发现CO_(2)热泵系统制热能力相对较强也更加节能,平均能耗降低了约35.4%。同时,CO_(2)热泵系统压缩机平均功率与R134a热泵系统的压缩机与正温度系加热器平均功率之和相比降低了约28.6%。

太阳能空气源热泵联合运行测试与分析

【目的】为了研究太阳能空气源热泵相结合的采暖系统实际运行状况,对实际运行的太阳能空气源热泵联合运行系统进行了测试。【方法】对呼和浩特市使用太阳能空气源热泵系统的2座加油站进行现场测试数据采集和分析,测试数据包括在不同的环境下的耗电量、供热量、温度等。【结果】根据实际的测量结果可知,当环境温度相差不大时,不同年份对应月份的耗电量也相差不大;当环境温度为-20℃时,系统性能系数COP依然能达到2.4以上。随着环境温度的升高,性能系数COP逐渐增大。当环境温度为5℃时,系统性能系数COP达4.0以上。【结论】太阳能辅助加热有助于提高热泵系统整体性能,是一种适合低温环境下运行的空气源热泵采暖系统。

Heating performance of a ground source heat pump system installed in a school building

The heating performance of a water-to-refrigerant type ground source heat pump system is represented in this paper under the actual working conditions of the GSHP(ground source heat pump) system during the winter season of 2008.Ten heat pump equipments with the capacity of 10 HP each and a closed vertical typed-ground heat exchanger with 24 boreholes of 175 m in depth were constructed.We investigated a variety of working conditions,including the outdoor temperature,the ground temperature,and the water temperature of inlet and outlet of the ground heat exchanger in order to examine the heating performance of the GSHP system.Subsequently,the heating capacity and the input power were investigated to determine the heating performance of the GSHP system.The average heating coefficient of performance(COP) of the heat pump was noted to be 5.1 at partial load of 47%,while the overall system COP was found to be 4.2.Also,performance of the GSHP system was compared with that of air source heat pump.

Simulation study on performance of a dual-source hybrid heat pump unit with alternative refrigerants

To solve the problems of single heat source heat pump systems in severe cold regions,a dual-source hybrid heat pump unit(DSHHPU)is proposed.The mathematical models of the DSHHPU when charging R134a or its alternative refrigerants R32,R290 and R600a were established respectively,and the performance was simulated and analysed.The results showed that the four refrigerants have different performance characteristics in different aspects.In heat pipe mode,the heating capacity and evaporating pressure of R32 are 36.94%and 59.94%higher than those of R134a.The heating capacity and evaporating pressure of R290 are 5.73%and 22.99%lower than those of R134a.The heating capacity and evaporating pressure of R600a are 43.29%and 68.08%lower than those of R134a.In vapour compression heating mode,the discharge temperature of R32,R290 and R600a are 184.88,72.98 and 66.44%of that of R134a.The coefficient of performance(COP)of R32,R290 and R600a are 72.65,111.59 and 117.94%of that of R134a.Finally,the effects of radiation intensity and ambient temperature on key performance parameters of the different refrigerants were analysed.The research results provide a reference for research on refrigerant replacements for multi-heat source composite heat pump systems.

跨临界CO_(2)水-水热泵系统的实验与仿真研究

为提高跨临界CO_(2)水-水热泵系统的效率,根据已有实验台建立系统仿真模型,分别进行实验测试和数值模拟,通过实验数据验证仿真模型的准确性。基于制取热水的目的,模拟分析运行参数对系统性能的影响,结果表明:增大过热度可提高性能系数(COP),用户侧供水温度平均提高11.3℃;随着高压压力的增大,用户侧供水温度升高,存在最优高压压力使COP最大;增大冷冻水的流量和升高进口温度,系统的制热效率可提高约40%,但用户侧供水温度变化不大。根据实验及仿真结果,设计太阳能辅助跨临界CO_(2)热泵双蒸发器系统,可实现3种不同运行模式,能够升高冷冻水进口温度、增大系统效率。与电加热锅炉和燃气锅炉进行经济性比较,太阳能热泵分别在第5年和第7年与上述两种加热方式的总投资持平,其运行20 a的总投资分别比燃气锅炉和电加热锅炉节约39%和49%,具有明显的经济优势和实用推广价值。

压缩机转速对空气源热泵机组制冷性能影响的试验研究

【目的】研究压缩机转速对空气源热泵系统制冷性能的影响。【方法】搭建以R410A为制冷工质的空气源热泵机组系统试验台,在标准焓差实验室进行试验。【结果】在标准制冷工况下,压缩机转速从2500 r/min增加到5500 r/min时,系统的制冷量增长了122.65%,压缩机功率增长了65.08%,系统的COP和EER分别增长了34.87%、46.99%,系统的排气温度及排气压力均上升,压比由3.04上升到4.26,而吸气压力呈下降趋势。【结论】压缩机转速为2500~4500 r/min时,系统的匹配性较好;压缩机转速在4500 r/min后,系统的匹配性较差。研究成果为后续进一步优化变频压缩机对空调或热泵系统的性能提供试验数据参考。

循环加热式热泵热水机试验装置用水泵对测试结果准确性的影响

在循环加热式热泵热水机(不带水泵)制热量测试系统中,水泵的补热会影响测试结果的准确性。本文分析闭式系统中的水经水泵做功后温度升高的原理,测试装置的标定试验结果表明,水泵功率的变化对标定结果影响的偏差为0%~7.3%,水泵功率的变化使得机组的制热量和能效测试结果均出现3.1%的偏差,指出重新标定试验装置可以使测试结果准确度控制在±0.5%以内。

电动汽车低温热泵系统台架及整车实验研究

热泵空调可明显改善电动汽车冬季制热工况下的能耗,提升整车续航里程。但由于其系统架构相对复杂,应用的零部件数量较多,较高昂的成本成为热泵技术广泛推广应用的制约因素。文章设计了一套结构相对简化,同时可满足整车冬季采暖需求的热泵系统。通过系统台架的搭建及测试,进行了该系统的充注量试验,分析了其在-7℃工况下的制热性能;并将该系统安装到整车上进行风洞测试,研究其冬季工况的制热特性,充分验证了该热泵空调系统在实际工程应用中的可行性。

吸附式制冷机及空调/热泵的运行实验和性能改进

研制了一台采用螺旋板式吸附器的连续回热型吸附式制冰机和一台采用板翅式吸附器的空调／热泵，给出了实验数据。吸附式制冷系统采用活性炭－甲醇吸附工质对，以９０—１００℃热水作为热源，实验得到单位质量活性炭的制冷能量密度为：制冰机每ｋｇ 吸附剂日制冰２．６ｋｇ，空调／热泵机组在空调工况下每ｋｇ 吸附剂制冷功率为１５０Ｗ。吸附空调系统经改进后ＣＯＰ达到０．３ 以上。实验结果表明，余热驱动的吸附式制冷具有实际应用价值。

充注量对小型热泵热水器性能影响的实验及分析

为了研究制冷剂充注量对小型空气源热泵热水器性能的影响,进行了不同充注量实验.根据实验数据分析了充注量的变化对加热时间、系统运行最大功率以及对蒸发压力、冷凝压力和系统性能系数(COP)等的影响.同时结合热力膨胀阀与蒸发器特性,分析充注量对系统稳定性的影响,提出了一个判断系统最佳充注量依据.比较了充注量变化对系统性能参数影响的敏感程度.研究结果可为小型热泵热水器的优化运行提供指导.

CO_2车用热泵空调系统技术研发及性能提升

本文研发了一套CO_2跨临界车用热泵空调系统,该系统采用CO_2车用电动压缩机、微通道换热器、电子膨胀阀等关键部件,克服了CO_2车用热泵空调系统高压和高排气温度的技术挑战。实验研究了系统充注量对CO_2车用热泵空调系统性能、循环特征及膨胀阀开度的影响。提出在热泵模式下将室内换热器串联来提高高压侧的换热能力,并实验验证了该方法对车用热泵空调系统性能的提升作用。结果表明:相比于单一气冷器,采用串联气冷器的车用热泵空调系统的制热量和COP_h分别提升了17%～31%和20%～33%;该系统在-20℃全新风环境下,出风温度可达40.4℃,COP_h为1.8。因此该系统能够满足电动汽车在低温环境下的乘客舒适性和整车负荷需求,且在制热能效方面优势显著。

对吸附式制冷/热泵循环理论的分析

以Ｄ－Ｒ方程为依据，在热力分析的基础上对吸附－解吸过程作了比较准确的描述。给出的模型中，重新考虑了Ｄ－Ｒ方程中各参数的物理意义，并充分考虑了工质对热物性如比热容、潜热等随温度变化的影响。基于该模型分析了几种重要因素如工质对的性质、循环工况、循环特性，尤其是吸附器的热容对吸附式制冷／热泵系统性能的影响，为系统的优化设计和优化运行提供了理论上的参考。

地源热泵桩基埋管传热性能测试与数值模拟研究

阐述了地源热泵地埋管传热性能的测试原理,并与热响应测试原理相对比。依据传热性能测试法,搭建实验台测试了4种桩基埋管在额定进口水温下的传热性能,并考查了不同进口水温对W型埋管传热性能的影响。进而采用数值模拟方法研究了不同埋管类型的传热性能,与测试结果相比有较好的吻合性。该文提出的传热性能测试方法和数值模拟方法可准确确定单位井深放热量,为地源热泵系统的优化设计提供参考。

固体吸附式冷管的制冷性能

提出了一种沸石 水工质对余热驱动的固体吸附式冷管 实验测试了冷管的制冷功率 ,研究了其在不同制冷功率时制冷温度的变化情况 实验研究了热源温度、环境温度、风速等参数对冷管制冷性能的影响 ,分析了其机理原因 研究结果为系统优化设计及吸附式冷管性能的进一步改进提供了重要参考 .提出了吸附式冷管型空调系统的工程化设计方案 .