升膜理论在氨水吸收式制冷循环中的应用

由于可以利用低品位热源制冷,氨水吸收式制冷系统得到了广泛的应用。氨水系统的精馏器要求很高的安装精度,限制了其应用范围。为了开发新型制冷器,将升膜理论应用到氨水吸收式制冷系统中,用一个冷凝发生器来实现精馏塔的作用。研究结果表明,本循环的热力系数比较高,这一成果可广泛应用于各种车、船等的制冷系统设计中。     

太阳能氨水吸收式家用制冷空调的开发与应用

介绍太阳能集热器和氨水吸收式制冷机的结构、原理和特点,对利用太阳能驱动氨-水吸收式制冷空调的可行性进行分析探讨,阐述研制开发太阳能氨水吸收式制冷空调对节能降耗保护环境的意义.     

氨水喷射-吸收式制冷循环的研究

对喷射增压的氨水吸收式制冷循环进行分析和热力计算，分别与一般的氨水吸收式循环相比，前在相同的热源温度下，获取的最低蒸发温度能够降低10℃左右，单级喷射-吸收系统的COP一直保持在O．3左右，双级喷射-吸收系统的COP在O．2左右。虽然在较高的蒸发温度段该制冷循环的性能系数略有降低，但是它能够利用现实中许多低品位的热源获取更低的蒸发温度。     

氨水吸收式制冷夹点分析法

氨水吸收式制冷需要消耗很大的公用工程,其性能系数(COP)不是很高,引入夹点分析法分析氨水吸收式制冷系统,该方法能够确定可回收的系统最大内部循环热,优化后的系统性能系数为0.623,比优化前的系统性能系数高11.58%。该方法对氨水吸收式制冷设计具有一定的指导意义。     

太阳能与地热结合利用的氨水吸收式循环

利用氨水吸收式循环将太阳能与地热两个热源结合，提出了一种新颖的制冷与供热系统。由于热源温差的协调配置，该系统具有更高的能量利用特性。还研究了热源温度以及重要内部操作条件对系统制冷、供热效率的影响规律，探讨了该系统的可行性。     

工业余热氨水吸收式制冷系统研究现状与发展趋势

由于我国节能减排政策的引导,工业余热氨水吸收式制冷系统以其节能减排、制冷效果好等优点越来越引起人们的关注。工业余热氨水吸收式制冷系统的研究主要集中在新型工质对的寻求、强化传热传质、优化制冷循环系统的研究等方面,特别是吸收器的吸收强化及活性剂的研究,成为工业余热氨水吸收式制冷系统的研究热点,通过对以上内容进行了详细分析,并指出今后的发展趋势。     

利用工业余热的溶液冷却吸收式双级氨水制冷循环研究

溶液冷却吸收式氨水制冷循环利用吸收器出口经泵升压后的浓溶液来冷却吸收过程的前段,回收了部分吸收热,从而可使浓溶液在逆流式溶液热交换器中部分发生,减少了对外界热源蒸汽的需求量.该循环流程同样也适用于利用工业余热等低品位能量作为发生器加热热源的双级氨水吸收式制冷循环,计算表明该改进型循环比传统循环的COP提高23%左右,同时换热器所需的总传热面积也有所减少.     

混合工质功冷联产循环与吸收式制冷循环的热力性能分析与比较

与传统单一吸收式制冷循环相比,混合工质功冷联产循环更有利于提高中温工业余热的利用效率,但能效提高的机理研究仍然不够深入。本研究构建了简化的氨水功冷联产循环系统和氨水吸收式制冷循环系统模型,提出了公平的比较基准,通过流程结构与热力学特性的分析和比较,揭示了混合工质功冷联产循环与吸收式制冷循环在能量转换与利用方面的差异,分析了功冷联产循环的性能提升机理。指出透平膨胀程度是影响热能在动力子循环与制冷子循环间分配比例和梯级利用程度的关键因素,并研究了其对系统性能的影响。     

线性唯象传热定律下不可逆四热源制冷循环最优性能

在恒温热源内可逆四热源吸收式制冷循环的基础上，考虑环境热源到制冷空间的热漏、工质的内部耗散以及工质与外部热源问的热阻损失，建立传热服从线性唯象定律的不可逆吸收式制冷循环的模型，导出循环的制冷率和制冷系数的基本优化关系、最大制冷系数及相应的制冷率和最大制冷率及相应的制冷系数，给出了最佳换热面积，并通过数值计算分析了设计参数对循环的制冷率、制冷系数的影响。所得结果对实际吸收式制冷机的设计和运行有一定的指导意义。     

无分凝器的氨水吸收式制冷循环系统研究

在常规单级氨水吸收式制冷循环的基础上,本研究提出了一种无分凝器的氨水吸收式制冷循环系统。应用能量和质量守恒方程对循环中不同部件分别建立热力学模型,通过运用C++软件编程,对两种循环的循环特性进行了模拟计算。结果表明:在发生温度为150℃,冷却水进口温度32℃工况下,随蒸发温度的升高无分凝器循环的性能系数越来越接近常规循环,在空调工况下最为接近;反之,越来越偏离常规循环。     

Performance improvement of absorption refrigeration system using triple-pressure-level

In the absorption refrigeration system (ARS) working with aqua–ammonia, the ejector is commonly located at the condenser inlet. In this study, the ejector was located at the absorber inlet. Therefore, the absorber pressure becomes higher than the evaporator pressure and the system works with triple-pressure-level. The ejector has two main functions: (i) aiding pressure recovery from the evaporator, (ii) upgrading the mixing process and the pre-absorption by the weak solution of the ammonia coming from the evaporator. In addition to these functions, it can also act to lower the refrigeration and heat-source temperatures. Energy analyses show that the system’s coefficient of performance (COP) and exergetic coefficient of performance (ECOP) were improved by 49% and 56%, respectively and the circulation ratio (f) was reduced by 57% when ARS is initiated at lower generator temperatures. Due to the reduced circulation ratio, the system dimensions can be reduced; consequently, this decreases overall cost. The heat source and refrigeration temperatures decreased in the range of 5–15 °C and 1–3 °C, respectively. Exergy analyses show that the exergy loss of the absorber of ARS with ejector had a higher exergy loss than those of the other components. Therefore, a multiple compartment absorber can be proposed to reduce the exergy loss of the absorber of ARS with ejector.     

Integration of a heat pump into the heat supply system of a cheese production plant

The food processing industry in Ukraine is widely developed and continues to develop. The majority of the enterprises of the food processing industry use the technological process with refrigerating cycles. Basically it uses ammonia refrigeration units. In existing ammonia refrigeration units waste energy from ammonia overheat after compression is not used. This waste energy can be used for heating of other technological streams. It can be achieved by detailed inspection of the technological streams system and further heat integration of the ammonia unit into a heating system of the enterprise. In this study an inspection of a cheese production plant has been conducted and the opportunity to heat integration of an existing ammonia refrigeration unit into technological process is considered. At present energy from ammonia superheating and condensation is not used and is expelled into the atmosphere through the cooling tower. There are two options for use of this heat: first without additional compression of ammonia and second with additional compression of ammonia stream. Both cases are considered.     

Numerical analysis of falling film absorption with ammonia–water in magnetic field

Absorption strengthen is an effective way to improve the coefficient of performance (COP) of ammonia–water absorption refrigeration system. A mathematical absorption model for ammonia–water falling film absorption in magnetic field was built in this paper to study the influence of magnetic field on the absorption process. Macroscopic magnetic field force was introduced to the mathematical model. Changes in physical properties of ammonia–water solution while absorbing, the variation of falling film thickness along falling and the convection in the direction of thickness of liquid film have been considered in modeling. Numerical results showed that magnetic field have positive effect on the ammonia–water falling film absorption to some degree. When the magnetic induction intensity at the solution’s inlet is 3 Tesla (T), the increment in concentration of ammonia–water solution at outlet is 1.3% and the absorbability increased by 5.9%. The COP of a simple ammonia–water absorption refrigeration system increased by 4.73% and the decrement in circulation ratio is 8.3%.     

喷射式氨-水吸收制冷系统的研究

在传统吸收制冷系统中引入喷射器,根据喷射器理论和吸收制冷循环理论,对新制冷系统的工作性能进行了模拟。分别探讨了冷凝温度、喷射器压缩比等参数对系统性能系数和发生温度的影响。结果表明,在原有吸收制冷系统结构变化不大的情况下,尽管系统性能系数有所下降,但系统发生温度却显著降低,因此,低品位的热源将有可能成为氨吸收制冷的加热热源,对于节能减排具有重要的意义。     

采用氨水溶液的先进蓄能系统工作特性研究(1)——工作原理及过程动态模型

对采用氨水溶液的变质量能量转换及储存系统的工作原理、工作循环和流程进行介绍。由于蓄能系统的能量转换过程是一个与时间有关的动态过程,常规的稳态制冷/热泵循环热力计算方法已不再适用,需给出一种新的动态热力计算方法。通过数值模拟来了解先进蓄能系统的工作特性,为进一步研究、开发该蓄能系统奠定理论基础。     

Proposal and analysis of a novel ammonia–water cycle for power and refrigeration cogeneration

Cogeneration has improved sustainability as it can improve the energy utilization efficiency significantly. In this paper, a novel ammonia-water cycle is proposed for the cogeneration of power and refrigeration. In order to meet the different concentration requirements in the cycle heat addition process and the condensation process, a splitting /absorption unit is introduced and integrated with an ammonia–water Rankine cycle and an ammonia refrigeration cycle. This system can be driven by industrial waste heat or a gas turbine flue gas. The cycle performance was evaluated by the exergy efficiency, which is 58% for the base case system (with the turbine inlet parameters of 450 °C/11.1 MPa and the refrigeration temperature below −15 °C). It is found that there are certain split fractions which maximize the exergy efficiency for given basic working fluid concentration. Compared with the conventional separate generation system of power and refrigeration, the cogeneration system has an 18.2% reduction in energy consumption.     

吸附制冷中回质过程的新模型及循环性能的研究

吸附式制冷在余热回收方面具有很好的前景，设计了用于大客车发动机余热回收的吸附式制冷系统，进行了分布参数的模拟计算，结果显示吸附床设计是比较合理的。同时建立了一种新的回质计算模型，提出了新的回质操作方法。模拟计算显示，回质是改善吸附循环性能的重要手段，回质过程提高了循环SCP和COP达一倍以上，回质过程非常迅速，5s即已完成，可以有效地缩短循环时间，提高循环性能。     

Exergy analysis of industrial ammonia synthesis

Exergy consumption of ammonia production plants depends strongly on the ammonia synthesis loop design. Due to the thermodynamically limited low degree of conversion of hydrogen–nitrogen mixture to ammonia, industrial ammonia synthesis is implemented as recycle process (so-called “ammonia synthesis loop”). Significant quantities of reactants are recycled back to reactor, after the removal of ammonia at low temperatures. Modern ammonia synthesis plants use well-developed heat- and cold recovery to improve the reaction heat utilisation and to reduce the refrigeration costs. In this work, the exergy method is applied to estimate the effect of the most important process parameters on the exergy efficiency of industrial ammonia synthesis. A specific approach, including suitable definitions of the system boundaries and process parameters, is proposed. Exergy efficiency indexes are discussed in order to make the results applicable to ammonia synthesis loops of various designs. The dependence of the exergy losses on properly selected independent process parameters is studied. Some results from detailed exergy analysis of the most commonly used ammonia synthesis loop design configurations at a wide range of selected parameters values are shown.     

氯化锶-氨吸附制冷性能的实验研究

建立了化学吸附式制冷实验单元，对氯化锶－氨工质对的制冷性能进行实验研究，得出不同热源温度下的制冷量，吸附速率、解吸速率等数据，并与活性炭－甲醇工质对进行了比较。