太阳能驱动风冷喷射式绝热吸收制冷循环研究

为改善太阳能吸收制冷循环性能并解决太阳能吸收制冷机风冷化问题,提出一种太阳能驱动的风冷喷射式绝热吸收制冷循环,通过喷射式绝热吸收器实现吸收过程的传热传质分别强化,同时回收高压溶液节流损失和再循环溶液的余压,以进一步增强吸收效果.构建组成循环各部件热力学数学模型,探讨了环境温度、发生温度、蒸发温度以及喷射器对新循环的影响...     

渔船发动机废热驱动的两级复叠吸收制冷循环性能分析

针对传统吸收式制冷无法达到较低温度以及自复叠吸收制冷在制得较低温度时系统性能系数过小的缺点,提出发动机废热驱动的两级复叠式吸收制冷循环用于捕获海产品的速冻保鲜。首先采用SRK方程获得了该循环高、低温级工质对R134a/DMF和R23/DMF的热力学性质参数,进而对循环进行了建模分析。通过直接搜索法得到了在不同工况下的最优高温级发生温度。发现在当吸收温度为30℃,冷凝温度为35℃,制冷温度在-40℃以上时,循环最佳蒸发冷凝温度和高、低温级发生温度分别为-3℃、106℃和140℃,此时循环COPint 可达到0.143。但该循环性能受吸收、冷凝温度影响较大,因此不太适合在海水温度过高的海域使用。     

一个新的吸收-喷射复合制冷循环

提出了一个新的吸收-喷射复合制冷循环.在新循环中,部分冷凝器出口的饱和液态制冷剂被冷剂泵加压到制冷剂在发生温度下对应的饱和压力,这股高压制冷剂液体在一个沸腾器里被加热成饱和高压蒸气后将预热器出口的过热制冷剂蒸气引射到冷凝压力.由于在新循环中发生压力可以比冷凝压力低,因此该系统可以利用较低品位的热量制取低温下的冷量.研究结果表明:新循环可以利用比传统两级吸收式制冷循环温度更低的热源,制取同一温度下的冷量.此外,在蒸发温度或发生温度较低时,新循环的COP比单效循环高得多;当发生温度或蒸发温度较高时,新循环和传统单效循环的COP相同.     

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。     

CO2-[emim][Tf2N]喷射-吸收冷热电联供循环㶲效率分析

针对传统吸收式冷热电联供循环存在制冷量和制冷效率低等缺陷,提出了一种新型低品位热驱动CO2-[emim][Tf2N]喷射-吸收冷热电联供循环.通过构建新型喷射-吸收冷热电联供循环理论模型及理论模拟计算,分析新循环的关键性参数对其性能的影响.结果表明:提高循环冷却水进口温度及冷冻水进口温度均可有效提高循环性能,冷却水进口...     

一个高效的两级吸收式制冷新循环

根据两级吸收式制冷循环本身的特点提出了一种新的两级吸收式制冷循环。研究结果表明:新循环比传统循环具有更高的效率和更低的吸收器负荷,而且在相同的蒸发温度时,发生终了温度越低,新循环相对传统循环COP的提高幅度以及吸收器负荷的减少幅度越大;相同发生终了温度时,蒸发温度越低,新循环相对传统循环的COP提高幅度以及吸收器负荷的减少幅度越大。     

一个带喷射器的两级吸收式制冷循环

提出一种带喷射器的两级吸收式制冷循环,部分低压发生器出口的制冷剂蒸气被高压发生器出口的制冷剂蒸气直接引射到冷凝压力。相比传统的两级吸收式制冷循环,由于部分制冷剂无需被高压溶液循环吸收和发生,因此新循环拥有更高的性能系数。以水-溴化锂作为工质的模拟结果显示,在部分工况下,新循环相对传统两级吸收式制冷循环的COP可提高20%以上。     

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。     

以太阳能为动力的喷射吸收制冷循环研究

本文研究一种以太阳能为动力的溶液再吸收与稀溶液增压的喷射吸收制冷循环，建立了相应的物理模型，以ＮＨ３－ＬｉＮＯ３做工质对进行了热力计算。结果表明，相地于传统吸收式制冷循环，该循环具有明显的优点；（１）高压稀溶液引射低压制冷剂蒸气，使吸收过程处于较高的压力状态，从而提高了吸收效果和循环的制冷效率；（２）在经济合理利用电能的前提下，通过增加泵功输入，可以大幅度提高制冷量，为低品位不稳定热源－－太阳能的     

低品位热驱动的混合工质喷射制冷循环研究

提出一种低品位热驱动的混合工质喷射制冷循环,将沸点相差较大的非共沸混合工质引入喷射制冷循环,采用两级分凝分离降低该新循环压比,实现在喷射制冷循环中获得较低的制冷温度和较高制冷效率。建立组成循环各部件热力学数学模型,在系统稳定运行的条件下,分析喷射器压比、冷凝温度和混合工质组分配比对新循环工作性能的影响。研究表明:采用混合工质R600/R290的喷射制冷循环可获得低于-20℃的制冷温度。     

Experimental study on an absorption refrigeration system at low temperatures

The heat-driven auto-cascade absorption refrigeration cycle can be used at low temperatures, and a novel auto-cascade absorption refrigeration system is proposed to gain better performances with a refrigerating temperature as low as −50 °C. The new system uses a mixture of R23 + R32 + R134a/DMF as its working pair and its characteristic study is carried out under different operational conditions. It has successfully obtained a refrigerating temperature of −47.2 °C under the generating temperature of 163 °C. This refrigerating temperature is far lower than that of a traditional absorption refrigeration system with the same working pair, and it is also lower than that of an auto-cascade absorption refrigeration system using R32 + R134a/DMF as its working pair. From the experimental results, it is clearly seen that this new system shows a rapider lowering rate of refrigerating temperature than that of an auto-cascade absorption refrigeration system using R23 + R134a/DMF as its working pair. The results of experimental analyses imply that this new absorption refrigeration system can be used in the deep-freezing as low as −50 °C by utilizing low-potential thermal power. Its potential of industrial application might be greater than that of an auto-cascade absorption refrigeration system using R23 + R134a/DMF as its working pair in the future.     

A new absorption refrigeration cycle using solar energy

A new type of absorption refrigeration cycle that is co-driven both by solar energy and electricity was evaluated. The principle of a heat transformer was applied to the absorption refrigeration system to increase its efficiency. In this paper, a thermodynamic model describing the performance of the new cycle was developed and a computer program was written to evaluate its performance. The COP, condenser heat load, the theoretical minimum evaporating temperature and refrigeration capacity for a typical daily load of the system were calculated and compared with those of traditional absorption refrigeration systems. The results show that the new cycle not only overcomes some shortcomings of the traditional absorption cycle with unsteady energy input from a variable source such as solar energy, but also increases the system’s coefficient of performance.     

太阳能固体吸收式制冰机的优化设计

对以ＣａＣｌ２／ＮＨ３为工质对的太阳能固体吸收式制冰机进行了优化设计。在维持系统总产氨量不变的前提下，尽可能地降低其工作温度，提高系统效率。模拟结果表明，采用新设计后制冰量有较大提高。     

Second law-based thermodynamic analysis of ammonia/sodium thiocyanate absorption system

In this study, the first and second law of thermodynamics are used to analyze the performance of a novel absorption system for cooling and heating applications. The active component of the sorbent used in this study is sodium thiocyanate (NaSCN). Ammonia (NH₃) is chosen as sorptive. A mathematic model based on exergy analysis is introduced to analyze the system performance. Enthalpy, entropy, temperature, mass flow rate and exergy loss of each component and the total exergy loss of the system are evaluated. Furthermore, the coefficient of performance (COP) and exergetic efficiency of the absorption system for cooling and heating processes are calculated from the thermodynamic properties of the working fluids under different operating conditions. The results show that the COP of cooling and heating increases with the heat source temperature and decreases with the cooling water inlet temperature, but the system exergetic efficiency does not show the same trends for both cooling and heating applications. The simulation results can be used for the thermodynamic optimization of the current system.     

水-溴化锂-硝酸锂与水-溴化锂吸收式制冷循环的比较

比较了水-溴化锂-硝酸锂三元工质与传统的水-溴化锂工质的单、双效吸收式制冷循环，分析了发生温度、冷凝温度和蒸发温度对系统性能的影响；同时也分析了直燃型双效制冷系统。结果表明：采用新工质后，系统的热力系数COP有了明显的提高，其它表征系统热力性能的经济指标也均有不同程度的改善，尤其在直燃型双效冷热水机组中有明显的优势，热力系数COP提高约30％，溶液循环倍率f降低12％。因此，该新工质与传统的水-溴化锂工质相比，具有较好的热力性能。     

溴化锂吸收式热泵的动态建模及运行特性分析

为充分挖掘吸收式热泵的动态运行特性,考虑各部件存量工质的储热特性建立考虑传质和分布参数的溴化锂吸收式热泵动态仿真模型。在机组各设备存量工质质量不同的情况下,分析了热源工质进口温度的提升对冷却水和冷媒水出口温度的动态影响及系统的热惯性特征,同时在热源工质进口、冷却水进口和冷媒水进口温度变化的情况下,分析了系统的性能系数(Coefficient of Performance, COP)变化特性及结晶风险变化特性。结果表明：该模型能准确地模拟吸收式热泵的稳态特性和动态特性;机组的热惯性主要与机组内各设备中的存量溶液质量有关;热源工质入口温度的上限受到系统COP及结晶风险的双重影响;冷却水入口温度的下降可增大系统COP,其下限受到结晶风险的限制;冷媒水入口温度的上限不受结晶特性限制;主要受用户侧的用能需求限制。     

A numerical investigation of a diffusion-absorption refrigeration cycle based on R124-DMAC mixture for solar cooling

Research on new working fluid for uses in absorption systems has been continued. The feasibility of a solar driven DAR using the mixture R124/DMAC as working fluid is investigated by numerical simulation. The cycle is simulated for two cooling medium temperatures, 27 °C and 35 °C, and four driving heat temperatures in the range [90 °C–180 °C]. The performance characteristics of this system is analyzed parametrically by computer simulation for a design cooling capacity of 1 kW. The results show that the system performance and the lowest (minimum) evaporation temperature reached are largely dependent upon the absorber efficiency and the driving temperature. It is shown that for solar applications this fluid mixture has a higher COP and may constitute an alternative to the conventional ammonia–water system.     

水工质波浪能装置液压系统及其监测系统的设计

针对波浪能发电装置的液压系统存在环境污染、安全性差和工作可靠性差等问题,设计一种以水为工质的波浪能发电装置液压系统,对系统组成和液压元件设计进行分析,有效解决传统油压传动存在的问题,为海洋环境中液压系统的优化设计提供一种新思路.同时设计一种基于STM32单片机的液压参数监测系统,可实现对压力、温度、流量、转速的实时监测...     

Performance analysis of dehumidification rotating wheel using liquid desiccant

In the present work, theoretical and experimental evaluation of the effect of bed configuration and operating conditions on the performance of desiccant dehumidification system has been carried out. A new rotating absorption disk has been designed and constructed to be tested in the experimental work. The desiccant wheel has a cylindrical shape of 50-cm diameter and 10 cm thickness. The flow area of this bed is consisted of 350 narrow slots, which are uniformly distributed over the cross section of the cylindrical bed. Each slot has a cylindrical shape and constructed from a steel spring of 100 mm length and 20 mm inside diameter. To form the absorbing surface in the bed, each spring is coated with a thick cloth layer impregnated with lithium chloride solution, which is used as the working desiccant in these experiments.In the theoretical part of this study, a mathematical model has been developed where its output results are compared with the experimental data. The effect of different design parameters and operating conditions on the absorption and regeneration processes is discussed. The effect of regeneration air temperature, the process air and regeneration air inlet humidity, the rotational speed, the process and regeneration air velocity (or flow rates), the bed length, etc. on the amount of water absorbed/desorbed in a cycle is investigated.For the specific bed design parameters, actual recorded data show that an amount of 95 g of water can be absorbed in the absorption cycle per hour. This value changes with varying the operating conditions. From the theoretical investigation, it is found that at regeneration temperature of 85 °C, the amount of water absorbed is nearly equal to the amount of water desorbed (i.e. equilibrium condition) for a complete cycle. It is seen also that for moderate operating conditions (50% RH, 30 °C) and lower regeneration temperature which is suitable for solar energy application, the reduction in the humidity ratio of the process air reaches about 13% of its initial value. Finally, comparisons between theoretical and experimental results show good agreement.