新型太阳能喷射与电压缩式联合制冷系统的研究

提出一种新型的太阳能喷射与电压缩联合制冷系统,其既可以利用太阳能喷射式制冷又可以利用电能驱动压缩式制冷,可提高太阳能与辅助能源的综合利用率。对该系统中以R141b作为制冷工质,采用斜盘式压缩机的辅助电压缩制冷系统进行了理论循环计算与实验研究。实验表明,该辅助电压缩制冷系统的性能系数达到2.53。与传统的辅助能源应用方式相比,该辅助电压缩式制冷系统能更高效地利用常规能源,提高新型太阳能喷射制冷系统的综合节能效果。     

太阳能喷射式制冷与电压缩制冷的能耗的对比

太阳能喷射式制冷系统在满足供冷需求时,通常需要补充一定量的一次常规能源,其节能条件及应用范围是急需解决的问题.在系统能量平衡的基础上,引入太阳能倍率等参数,推导了太阳能喷射式制冷系统与电压缩制冷系统的一次能耗比计算公式,进而对太阳能喷射式制冷系统与电压缩制冷系统的一次能源消耗进行了对比分析.并以太原为例,确定了太阳能喷射式制冷系统的平衡太阳能倍率,给出了相对于电压缩制冷的太阳能喷射式制冷的节能条件.     

冷暖联供太阳能喷射制冷系统的一次能耗

太阳能喷射式制冷(热泵)系统在满足供冷、供热需求时，通常需要补充一定量的一次常规能源。该文在系统能量平衡的基础上，引入太阳能倍率、冬夏负荷比等参数，推导了太阳能制冷系统与电压缩制冷系统的一次能耗比计算公式。进而对太阳能双元混合工质喷射式制冷(热泵)系统、单元工质喷射式制冷系统、太阳能直接供热系统与电压缩制冷系统的一次能源消耗进行了对比分析。结果表明，太阳能喷射式热泵比太阳能直接供暖系统节约一次常规能源；太阳能喷射式制冷(热泵)系统，在其太阳能倍率位于节能区时，比电压缩制冷(热泵)系统节约一次常规能源。     

基于主动平衡的喷射式制冷系统实验研究

针对空调系统用电占比上升,喷射式制冷系统成为压缩式制冷系统有前景的替代方案。传统喷射式制冷系统由于泵的存在,降低了系统的COP和稳定性,还会带来汽蚀和密封失效等问题。针对传统系统的不足设计开发了以R245fa为工质的主动平衡喷射式制冷系统,进一步简化系统结构提升系统能效。实验研究了主动平衡系统发生压和、冷凝压力和蒸发压力的变化规律以及储液罐热容等参数对系统运行及能效的影响。结果表明：主动平衡系统发生压力、冷凝压力、蒸发压力随时间周期性波动;参数周期性骤变后能迅速恢复正常,喷射器在实验周期性波动工况下能维持稳定运行;冷凝储液罐热容对系统能效有不利影响;使用主动平衡系统能够节省泵功,系统COP有所提升,性能优于传统喷射式制冷系统。     

基于熵权-TOPSIS的光电光热制冷系统评价与分析

以三亚市某办公建筑为例，基于TRNSYS建立传统制冷系统、太阳能光电制冷系统和太阳能光热制冷系统，并对系统进行能耗模拟。然后以能源、经济和环境效益作为评价指标，使用熵权-TOPSIS法对传统制冷系统、光电制冷系统的两种不同方案、光热制冷系统进行综合评价，并对各方案进行比较。结果表明：太阳能光电制冷系统的两种不同方案的综合效益显著优于传统制冷系统；按耗电量匹配的光电制冷系统方案优于按最大安装面积匹配的系统方案；并且太阳能光电制冷系统比太阳能光热制冷系统具有更好的综合效益。     

太阳能喷射式制冷系统性能分析

叙述了太阳能增压喷射式制冷的原理和系统工作过程. 探讨了太阳能喷射式制冷系统研究的进展状况.通过计算研究了多种制冷剂对喷射器工作性能和系统制冷系数的影响.应用数学模拟的方法,分析了太阳能增压喷射式制冷系统在实际日照条件下的工作性能.结果表明,这种系统能够利用太阳能提供实际需要的制冷量.     

太阳能驱动喷射复合压缩式制冷空调系统设计

为北京市某综合楼设计了一种喷射复合压缩式制冷空调系统,阐述其运行原理、负荷计算、R245fa为工质的喷射式制冷设计计算、空调系统设计计算及选型等,通过对比新复合式空调系统和传统压缩制冷系统的能耗,得出新复合式空调系统可节电23.18%,系统性能提升超过30%,认为其具有一定的发展前景。     

中国首个太阳能空调系统现身江苏盱眙

7月11日下午，中国首个利用太阳能制冷技术储存国家储备粮的空调系统，由南航专家在江苏盱眙县调试成功。据该项目专家组成员、南京航空航天大学能源与动力学院副教授韩东介绍，太阳能制冷系统主要由太阳能热水系统、压缩式制冷系统等两部分组成。其太阳能热水系统与普通家用太阳能热水器原理一样，只是数量更多、功率更大，可使水温升至90℃左右。     

太阳能喷射式制冷系统性能的实验研究

对太阳能喷射式制冷系统进行了实验研究,采用电加热模拟太阳能辐射的方法,研究了冷凝器、发生器和蒸发器温度对制冷系统COP的影响,给出了太阳能喷射式制冷系统制冷能力与COP随时刻的变化关系。系统在80℃热源条件下,全天提供16℃的冷水,系统最大制冷量为0.43 kW。     

两级喷射式太阳能制冷系统的压缩比研究

提出了一种新型的太阳能喷射制冷系统--两级喷射式太阳能制冷系统,该系统的最大特点是以喷射器两级串联的方式来实现系统冷凝端的风冷冷凝.建立了该系统的物理模型和数学模型,分析了系统的性能和工作特性;在给定的系统蒸发、冷凝和发生器温度下,计算了R141b、R134a、R123和R22四种制冷剂的COP与两级间压缩比的分配度i的变化关系;得到了该四种制冷剂的压缩比变化对喷射系数的不同影响程度;提出了系统总压缩比在5.8以下和5.8以上的两级压缩比分配原则.     

太阳能喷射/压缩复合制冷循环性能研究

研究了一种太阳能喷射/压缩复合制冷循环,由太阳能集热子系统、喷射制冷子系统及压缩制冷子系统组成,系统充分利用热电两种能源以及两种制冷方法各自的优点,优化喷射制冷子系统工作性能的同时,改善压缩式子系统的工作条件,从而提高复合制冷循环性能的同时节约高品位电能。采用性能较好的高蒸发温度式喷射制冷带走压缩机排气余热具有实际意义。通过数值模拟的手段分析系统性能及其主要影响因素,并优化工作条件。研究表明,与相同工作条件下的单压缩制冷循环相比,复合制冷循环工作日全天候运行时电力性能系数提升约为31.5%,节电优势显著。存在一个最佳的喷射子系统蒸发温度使得复合制冷循环性能系数达到运行工况的最大值。     

A novel solar bi-ejector refrigeration system and the performance of the added injector with different structures and operation parameters

A novel solar bi-ejector refrigeration system was investigated, whose difference compared to the traditional system is that the circulation pump is replaced by a thermal injector. The new system works more stably and needs less maintenance work than the old one, and the whole system can more fully utilize the solar energy. The mathematical models for calculating the performance of the injector and the whole solar refrigeration system were established. The pressure rise performance of injector under different structure and operation parameters and the performance of solar bi-ejector refrigeration system were studied with R123. The results show that the discharged pressure of injector is affected by structure dimensions of injector and operation conditions. With increasing generation temperature, the entrainment ratio of ejector becomes better while that of injector becomes worse and the overall thermal efficiency of the solar bi-ejector refrigeration system first increases and then decreases with an optimum value of 0.132 at generation temperature of 105 °C, condensation temperature of 35 °C and evaporation temperature of 10 °C.     

A new combined adsorption–ejector refrigeration and heating hybrid system powered by solar energy

In this paper the design scheme of a new continuous combined solid adsorption–ejector refrigeration and heating hybrid system driven by solar energy was proposed, the thermodynamic theory of this system was constructed, and the performance simulation and analysis were made under normal working conditions. In the combined hybrid system, zeolite–water working pair was chosen in view of environment protection and solar energy utilization. From simulation the combined hybrid system had a cooling capacity of 0.15 MJ per kg zeolite in the day-time and a cooling capacity of 0.34 MJ per kg zeolite in the evening, and could furnish 290 kg hot water at 45 °C for family use. Furthermore, under the same working conditions, compared with an adsorption system without an ejector with a COP of 0.3, the combined system's COP was improved by 10% totally and reached 0.33.     

有机郎肯循环复合系统中喷射器能量分析

有机郎肯循环利用太阳能、地热能和余热驱动,是回收余热、实现能源可持续发展的一个很好途径。有机郎肯循环可与喷射制冷循环结合,可同时提供电能和冷量。喷射器内部流体的不可逆混合引起的能量损失,是该系统最大部分的能量损失。着眼喷射器内部流场分布和机理,分析工作参数和几何参数对其性能的影响,以优化喷射器设计,减小系统能量损失,提高带有喷射器的有机郎肯循环复合系统的效率和节能潜力。结果显示,提高引射压力和出口压力会导致喷射器内部更多能量损失,制约整体系统的性能;在给定工况下,可通过钝化喷嘴内壁面、喷嘴处于最佳位置使喷射器达到最大喷射系数、最优性能,和最小的能量损失。     

Energy and exergy analysis of novel solar bi‐ejector refrigeration system with injector

Energy and exergy balances were done on a novel solar bi‐ejector refrigeration system with R123, whose circulation pump is replaced by an injector. The analysis result of the novel system was compared with that of the original one. The effect of operation condition on system energy efficiency, exergy efficiency and exergy loss was analyzed, and the dynamic performance of a designed solar bi‐ejector refrigeration system was also studied. The comparative results indicate that under the same operating condition, the novel system and the original system have equal energy efficiency, exergy efficiency and exergy loss, and the only difference between them is the exergy losses of the generators and the added injector. The other conclusions mainly include: the solar collector has the largest exergy loss rate of over 90% and for the bi‐ejector refrigeration subcycle, the ejector has the largest exergy loss rate of about 5%; the total exergy loss changes inversely proportional to the evaporation temperature and positively proportional to the condensation temperature; when the other parameters are fixed, there exists an optimum generation temperature, at which the overall energy and exergy efficiencies are both the maximum and the total exergy loss is the minimum. The study points out the direction for optimizing the novel solar bi‐ejector refrigeration system. Copyright © 2009 John Wiley & Sons, Ltd.     

A novel approach to improve the performance of solar-driven Stirling engine using solar-driven ejector cooling cycle

In this paper, a novel system to enhance the performance of a solar-driven finite speed alpha-type Stirling engine is proposed and evaluated. Part of the concentrated solar energy is used to drive an ejector refrigeration system. The cooling produced in the ejector cooling cycle is used to cool the Stirling engine to enhance its efficiency. Model equations to describe the systems are proposed and solved numerically. The results indicate that the new system produces averagely 3.3 times electrical power more than the conventional one. Moreover, the proposed system improves the Stirling engine efficiency by up to 46% in comparison with 19.15% for the conventional Stirling engine under solar radiation intensity of (1 kW/m²). Also, the results showed that the solar radiation intensity and wind speed are the most influential parameters that affect the proposed system efficiency. The new system is recommended to use in desert climates where high average daily solar radiation intensity, low wind speeds, and water shortage exist. Economic analysis is carried out to determine the feasibility of the proposed system under different economic parameters. It is found that, for instance, the simple payback period is 4.64 years for the new system when the selling price of electricity is 0.35 $/kWh.     

Numerical Simulation of the Performance of a Capillary Thermal Driven Ejector Refrigerator

A capillary driven ejector refrigerator is a new refrigeration system that can use solar energy and other low-grade heat sources. In this paper, the performance of the refrigeration system is simulated numerically by use of an iteration algorithm and block exchanging technology for all unit models. The flow and heat transfer characteristics in a solar collector, generator, ejector, condenser, and evaporator are analyzed and calculated. The results show that when the generating temperature is higher than 75–80°C and the environmental temperature is lower than 35°C, the system can work normally; the coefficient of performance of this refrigeration system is in the range of 0.05–0.15 by use of water as a refrigerant. The cooling capacity and COP increase with an increasing generative temperature and decreasing condensing pressure.