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1.
建立多太阳能集热蒸发器并联热泵系统的实验装置,分析在正常和恶劣工况下,太阳能热泵集热蒸发器的热性能。结果表明,在相同太阳辐照量的条件下,各太阳能集热蒸发器出口处过热度与压缩机进口处过热度基本一致,且均能正常工作;不论在正常工况还是恶劣工况下,蒸发器阵列的整体性能均可满足要求;通过比较多太阳能集热蒸发器并联热泵热水系统与空气源热泵热水系统COP可知,多太阳能集热蒸发器并联热泵热水系统COP基本维持在5.0~6.0之间,相比于空气源热泵热水系统COP在2.0~3.0之间有明显优势;证明多太阳能集热蒸发器并联形成一个大的太阳能热泵系统是可靠的。  相似文献   

2.
该文建立直膨式多太阳能集热蒸发器并联热泵系统的实验装置,分析在极端工况下,单个太阳能集热蒸发器的热性能和蒸发器阵列的整体热性能及其对系统运行的影响。结果表明在极端工况下,虽然A、B组蒸发器的吸热量存在差异,甚至A组蒸发器出口处制冷剂的过热度接近零,但是系统性能系数COP达3.69,所以蒸发器阵列的整体热性能满足要求;吸热量较多的蒸发器组,其出口处制冷剂过热度大,进一步验证了直膨式多太阳能集热蒸发器并联热泵系统是可靠的。  相似文献   

3.
太阳能-空气复合热源热泵热水器的性能模拟与分析   总被引:2,自引:0,他引:2  
徐国英  张小松 《太阳能学报》2006,27(11):1148-1154
介绍了一种新型太阳能—空气复合热源热泵热水装置(SAS-HPWH)。该装置通过使用独特设计的螺旋翅片蒸发管的平板型集热/蒸发器,可以在不同的天气情况下切换运行太阳能热源热泵模式、太阳能与空气双热源热泵模式和空气源热泵模式,制取生活热水。论文主要针对自行设计的一台150L的SAS-HPWH,建立系统的数学模型,并以太阳能输入比例为准则研究系统的运行模式与特性。模拟结果显示该热水器在不同天气特征情况下可高效率地制造55℃热水。论文还分析了太阳辐射、环境温度以及压缩机的容量对系统特性的影响,提出使用变频压缩机,根据不同的天气情况调节制冷剂流量,进一步提高系统的整体性能。  相似文献   

4.
太阳能和空气源复合热泵在不同模式下具有不同性能,如何在实际应用中以最佳的工作模式运行,对提高系统综合性能至关重要,为此提出2种用于实现系统最优模式切换的判断方法:1)基于最优模式切换的太阳能辐射强度和环境温度的复合环境参数范围表;2)流经2个蒸发器(太阳能集热/蒸发器和风冷蒸发器)的制冷剂质量流量分配比。基于此,在工程方程求解器(EES)中建立太阳能/空气双源辅助热泵热水器的仿真模型。首先,基于上海松江地区的气候条件模拟比较不同模式下的系统性能,再分析和讨论将复合环境参数范围表和质量流量分配比作为系统最优模式切换的判断方法的可行性。结果表明,在相同环境温度下,随着太阳辐射强度的增加,系统最优运行模式将由太阳能-空气模式转变为太阳能模式。此外,将流经2个蒸发器的制冷剂质量流量分配比作为模式切换的准则是可行的,对于本系统其最优运行模式由太阳能-空气模式转变为太阳能模式时的质量流量分配比临界值约为2.02。  相似文献   

5.
新型平板热管式PV/T热泵系统的集热模块优化研究   总被引:1,自引:0,他引:1       下载免费PDF全文
建立了新型平板热管式PV/T热泵系统的数学模型,通过实验测量得到系统在各工况下运行时的实验数据,并验证了模型的准确性和可靠性。基于验证后的数学模型,对系统的热性能、电性能和热泵系统的性能进行模拟研究。结果表明,在冬季工况下,系统的日平均热功率、电功率和COP分别为274.5 W、93.5 W和2.7。由于冬季室外环境温度较低,在冬季运行时,集热系统会通过光伏板表面向周围环境散失大量的热,导致系统的集热量不能满足热泵侧的热需求,直观表现为蒸发侧集热水箱水温在全天呈现下降的趋势。因此通过增加集热器对系统的集热模块进行优化,优化后系统的日平均热功率提升至654.2 W,COP提升至6.9。  相似文献   

6.
新型平板热管式太阳能PV/T集热系统的性能研究   总被引:1,自引:0,他引:1  
文章搭建了新型平板热管式太阳能PV/T集热系统实验台,测试了该集热系统的热电性能。此外,建立了该集热系统的数学模型,并将该集热系统的测量结果和模拟结果进行对比分析,以验证该数学模型的准确性。最后,在相近的测试条件下,对新型平板热管式太阳能PV/T集热系统和传统圆形热管式太阳能PV/T集热系统的热电性能进行对比分析。分析结果表明,在相近的测试条件下,与传统圆形热管式太阳能PV/T集热系统相比,新型平板热管式太阳能PV/T集热系统的日平均热效率和日平均电效率分别提升了16.8%和3.5%,总集热量和总发电量分别提升了78.4%和35.5%。  相似文献   

7.
传统空气源热泵在较低环境温度下存在制热量不足和制热效率偏低问题,该文提出一种太阳能辅助的双源双压缩耦合热泵系统,通过集热器将太阳能转化为低温热水以构建太阳能水源热泵单元,利用2台压缩机和1台冷凝器实现太阳能水源热泵单元和空气源热泵单元并联耦合工作。太阳能水源热泵单元和空气源热泵单元既能各自独立运行又能同时运行以满足用户全天候热负荷需求。基于DeST软件评估一个供热期(120 d)郑州某建筑逐时热负荷特性。在建立热力学数学模型基础上编写程序进行新系统循环特性计算和能耗分析,结果表明:双源耦合热泵系统COP_h较传统空气源热泵明显升高;前者日节能率介于1.01%~14.75%之间,在整个供热期总能耗较后者减少8.72%。双源(空气源蒸发器和水源蒸发器)双压缩机并联流程耦合热泵比双源单压缩机串联流程耦合热泵更具有节能优势。  相似文献   

8.
以直膨式太阳能热泵系统的集热/蒸发器为研究对象,设计一种新型优化集热/蒸发器,通过实验对比测试其在换热能力、温度均匀性、流动压力损失方面与原型集热/蒸发器的差异。研究结果表明:在环境温度为4.7℃,平均辐照度为454.8 W/m2的工况条件下,采用新型优化集热/蒸发器的系统COP可达到4.3,得热因子为1.752,无量纲压强损失系数为0.05,均优于原型集热/蒸发器,为集热/蒸发器的设计优化理论提供了实验验证。  相似文献   

9.
对直膨式太阳能热泵系统的集热/蒸发器结构进行优化,设计由六边形与四边形单元组合的流道结构,并进行仿真与实验研究。在上海地区,冬季工况下,将水温从10℃加热到50℃,系统COP可达到4.5;夏季工况下,将水温从30℃加热到55℃,系统COP可达到6.60。在此基础上,针对严寒地区冬季运行,研究了与喷气增焓循环耦合的低温型直膨式太阳能热泵系统。在环境温度为-10℃时,系统COP可达到3.79;环境温度为-20℃时,系统COP可达到3.69。依据实验与仿真数据,运用全生命周期经济性分析方法,以当量热价(LCoH)为评价指标,为太阳能热泵采暖经济性分析提供计算方法和理论依据。  相似文献   

10.
季杰  赵方亮  黄文竹 《太阳能学报》2016,37(10):2578-2584
直膨式太阳能热泵(direct expansion solar assisted heat pump,DX-SAHP)可直接吸收利用太阳能,进而提高热泵的蒸发温度和性能系数(COP),有利于改善热泵的热性能和结霜。本文在带有太阳模拟发射器的焓差实验室中建立直膨式太阳能热泵和常规直彭热泵的对比实验,对不同条件下的热泵系统参数进行测量并进行性能对比和分析。实验结果显示,直膨式太阳能热泵能够吸收太阳能,在辐照度分别为100和200 W/m~2的工况下,系统制热功率比无辐照时的制热功率分别提高9.8%和21.8%,COP分别提高11.7%和23.7%,且除霜启动延迟23 min;辐照度为200 W/m~2时,直膨式太阳能热泵在环境温度5℃下的制热功率比1℃下的制热功率提高16.92%;在室外温度为1℃,相对湿度为95%的工况下,提高太阳辐照度,可有效减小涂层蒸发器进出口温度的波动,提高蒸发器运行的稳定性。此外,直膨式太阳能热泵在运行过程中吸收的太阳辐射被用来蒸发液态制冷剂工质,导致压缩机进气量增加,系统的制热功率和COP提高。  相似文献   

11.
对直接膨胀式太阳能热泵热水系统进行了实验研究,实验期间,太阳能辐照度变化范围为143.12~664.6 W/m2,分别采用三种不同结构的集热器和蒸发器,得出系统COP为2.49~3.47,表明该系统在各种天气情况下均能够可靠地生产45℃的生活热水,热性能稳定,可以全天候地提供生活热水且具有节能效果;同时选取双集热器的两组数据,分析了太阳辐照度对热泵系统运行的影响。  相似文献   

12.
Thermal performance of a direct expansion solar-assisted heat pump   总被引:2,自引:0,他引:2  
A direct expansion solar assisted heat pump, in which a bare flat plate collector also acts as the evaporator for the refrigerant, Freon-12, is designed and operated. The system components, e.g. the collector and the compressor, are properly matched so as to result in system operating conditions wherein the collector/evaporator temperature ranges from 0 to 10°C above ambient temperature under favorable solar conditions. This operating temperature range is particularly favorable to improved heat pump and solar collector performance. The system thermal performance is determined by measuring refrigerant flow rate, temperature and pressure at various points in the system. The heat pump COPH and the solar collector efficiency ranged from 2.0 to 3.0 and from 40 to 70 per cent, respectively, for widely ranging ambient and operating conditions. Experimental results indicate that the proposed system offers significant advantage in terms of superior thermal performance when compared with results gotten by replacing the solar evaporator with a standard outdoor fan-coil unit.  相似文献   

13.
针对液化天然气(liquefied natural gas,LNG)空温式气化器(ambient air vaporizer,AAV)在运行中表面堆霜结冰降低换热效率的问题,提出并设计一种基于太阳能热泵的LNG气化系统(DX-SAHPNV),建立系统各主要部件的动态仿真数学模型。通过数值模拟,对DX-SAHPNV改善AAV气化能力的效果和系统全年动态运行性能进行研究,并对比分析集热/蒸发器内引入LNG前后系统性能的变化。结果表明:同常规AAV相比,应用DX-SAHPNV系统后,冬、夏典型日AAV液相区和两相区长度明显缩短,结霜量减少,出口天然气平均温度分别升高3.31和7.46 K;同不引入LNG相比,DX-SAHPNV系统引入LNG时,冬、夏典型日COP分别提高9.25%和16.49%,集热效率分别提高11.07%和14.95%,DX-SAHPNV系统全年COP均值和集热效率均值分别提高13.64%和12.84%。DX-SAHPNV系统可有效提高AAV气化效果。  相似文献   

14.
The thermal performance of two different schemes of solar‐assisted heat‐pump systems has been theoretically studied. In first scheme, the evaporator of the heat pump is taken directly as the solar collecting plate and always maintained at the ambient temperature. As there is no heat loss from the collecting plate, the thermal efficiency of the collector is high and equals the solar absorptivity of the collecting plate. As suggested, the heat‐pump evaporator of the second scheme is placed in a novel fresh water solar pond/tank with high efficiency. Since the evaporator operates at a relatively high temperature, the COP of the heat pump can be increased. The calculated results show that the COP of a solar‐assisted heat pump using the second scheme is considerably higher than that of the first scheme. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

15.
Analytical and experimental studies were performed on a direct‐expansion solar‐assisted heat pump (DX‐SAHP) water heating system, in which a 2 m2 bare flat collector acts as a source as well as an evaporator for the refrigerant. A simulation model was developed to predict the long‐term thermal performance of the system approximately. The monthly averaged COP was found to vary between 4 and 6, while the collector efficiency ranged from 40 to 60%. The simulated results were used to obtain an optimum design of the system and to determinate a proper strategy for system operating control. The effect of various parameters, including solar insolation, ambient temperature, collector area, storage volume and speed of compressor, had been investigated on the thermal performance of the DX‐SAHP system, and the results had indicated that the system performance is governed strongly by the change of solar insolation, collector area and speed of compressor. The experimental results obtained under winter climate conditions were shown to agree reasonably with the computer simulation. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

16.
The performance of a photovoltaic solar assisted heat pump (PV-SAHP) with variable-frequency compressor is reported in this paper. The system is a direct integration of photovoltaic/thermal solar collectors and heat pump. The solar collectors extract the required thermal energy from the heat pump and at the same time, the cooling effect of the refrigerant lowers the working temperature of the solar cells. So this combined system has a relatively high thermal performance with an improved photovoltaic efficiency. To adapt to the continuously changing solar radiation and ambient temperature conditions, the refrigerant mass flow rate should match the heat gain at the evaporator accordingly. A variable-frequency compressor and an electricity-operated expansion valve were used in the proposed system. Mathematical models were developed to evaluate the energy performance of the combined system based on the weather conditions of Tibet. The simulation results indicated that on a typical sunny winter day with light breeze, the average COP could reach 6.01, and the average electricity efficiency, thermal efficiency and overall efficiency were 0.135, 0.479 and 0.625 respectively.  相似文献   

17.
《Applied Thermal Engineering》2001,21(10):1049-1065
Analytical and experimental studies were performed on a solar assisted heat pump water heating system, where unglazed, flat plate solar collectors acted as an evaporator for the refrigerant R-134a. The system was designed and fabricated locally, and operated under meteorological conditions of Singapore. The results obtained from simulation are used for the optimum design of the system and enable determination of compressor work, solar fraction and auxiliary energy required for a particular application. To ensure proper matching between the collector/evaporator load and compressor capacity, a variable speed compressor was used. Due to high ambient temperature in Singapore, evaporator can be operated at a higher temperature, without exceeding the desired design pressure limit of the compressor, resulting in an improved thermal performance of the system. Results show that, when water temperature in the condenser tank increases with time, the condensing temperature, also, increases, and the corresponding COP and collector efficiency values decline. Average values of COP ranged from about 4 to 9 and solar collector efficiency was found to vary between 40% and 75% for water temperatures in the condenser tank varying between 30°C and 50°C. A simulation model has been developed to analyse the thermal performance of the system. A series of numerical experiments have been performed to identify important variables. These results are compared with experimental values and a good agreement between predicted and experimental results has been found. Results indicate that the performance of the system is influenced significantly by collector area, speed of the compressor, and solar irradiation. An economic analysis indicates a minimum payback period of about two years for the system.  相似文献   

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