太阳能固体吸附式制冷系统部件的实物设计

对太阳能固体吸附式制冰机系统的关键零部件吸附床、冷凝器、蒸发器加以分析,并进行了实物设计。实验结果表明,所设计的系统零部件在太阳能固体吸附式制冰机装置实际运行工况下具有较好的传热、传质特性,系统各子部件间运行时能够很好地匹配,为太阳能制冷空调的实用化奠定了良好的基础。     

平板式太阳能固体吸附式制冰机的设计

设计了一台以太阳能为驱动源的固体吸附式制冰机，并对该装置进行了性能实验，实验结果表明，该装置具有较好的传热传质特性，并有效地解决了系统的真空泄漏问题，系统各子部件之间匹配性能良好，多次重复运行得到相同的实验结果。     

太阳能固体吸附式制冰机热动力学性能分析模型及实验

分析了太阳能固体吸附式制冷装置中吸会床的传热传质计算过程,给出了求解模型的具体方法,运用数值传热学的方法,计算了在一定日照国徽能量条件下,系统装置的吸附床内的温度场分布,实验表明,所建立的模型能对太阳能固体吸附式制冷装置进行了性能动态模拟,为系统装置的优化设计提供了参考。     

国内可再生能源文献信息

生物质密致燃料层燃锅炉温度场的研究；太阳能制冷技术的研究概况;西藏能源利用现状及发展探讨；三种生物质气催化制甲醇的比较；小型固体吸附式太阳能空调装置的实验研究；槽型聚光集热系统加热真空管的特性及应用研究；大型太阳能空调／热泵系统；[编者按]     

太阳能固体吸附式制冷技术应用的一些探讨

总结了自行设计的太阳能固体吸附式制冷装置所取得的一些成果,对太阳 能固体吸附式制冰机系统的实际应用从工艺上、操作上、成本上作了分析与说明,并对 进一步开展太阳能固体吸附式制冷装置的研究作出了展望。     

太阳能固体吸附式制冰机间隙制冷现象的研究

对整体无阀结构太阳能固体吸附式制冰机在真实环境工况下进行实验研究，得出在外界云层影响下太阳能固体吸附式制冰机的性能特性。采用经实验验证后的传热传质模型，分析了太阳能制冰机受外界云层影响下所表现出的间隙制冷效果。实验与理论两方面的工作为太阳能固体吸附式制冰机的合理应用提供了区域气候选择的依据，为科学分析太阳能制冰机性能提供了客观的基础。     

太阳能固体吸附式制冰机系统内外特性分析

利用所建立并通过实验证的数学模型，从吸附床的内部特性参数及外部特性参数出发，对所设计制造的太阳能平板式制冰机系统进行分析，较为全面而系统地分析了内部参数及外部参数的改变对太阳能固体吸附式制冰机的性能系统COP及制冰特性的影响，为新一轮的太阳能固体吸附式制冷机装置的设计与制作提供了一个全方位的优化设计基础。     

固体吸附式太阳能空调系统中工质对性能的比较研究

利用重量法测量了几种可用于固体吸附式太阳能空调系统中工质对的性能，分析了压力、温度等因素对吸附量的影响，建立了吸附量回归公式，比较了不同工质对之间的优劣，指出了适合于太阳能空调系统的吸附工质对要求。     

太阳能固体吸附式制冷吸附床的设计

描述了固体吸附式制冷系统中吸附床的作用和功能,比较分析了现有太阳能固体吸附式制冷装置的吸附床。通过两种吸附床装置的具体分析,提出了合理设计太阳能吸附床装置的途径。     

太阳能固体吸附制冷系统的设计研究

本文在综合前人研究成果的基础上，分析了可为吸附式制冷系统装置供热的太阳能集热装置的类型和特性，探讨了集热装置的设计以及与固体吸附式系统的结合方式。并围绕着影响系统效率的各种因素，研究了系统各个部分的设计方法。在分析系统整体运行特性的基础上，提出了系统整体的设计方案。     

Solar-powered systems for cooling, dehumidification and air-conditioning

This paper describes current trends in solar-powered air conditioning, which has seen renewed interest in recent years due to the growing awareness of global warming and other environmental problems. Closed-cycle heat-powered cooling devices are based mainly on absorption chillers, a proven technology employing LiBr–water as the working fluid pair. Recent developments in gas-fired systems of this type make available double- and triple-effect chillers with considerably higher COP than their single-effect counterparts, which makes it possible to reduce the amount of solar heat required per kW of cooling. These systems require, however, high-temperature solar collectors. The principles of multi-staging absorption systems are described. An economic comparison is provided which shows the total system cost to be dominated by the solar part of the system. At current prices, the high COP, high temperature alternative is still more costly than the low temperature one. Open-cycle desiccant systems employing either solid or liquid sorbents are described. While the main thrust in research on novel closed-cycle absorption systems has been toward increasing the operating temperature in order to improve efficiency through multi-staging, open-cycle absorption and desiccant systems have been developed for use with low temperature heat sources such as flat plate solar collectors. A novel open-cycle (DER) system is described, which makes it possible to use the solar heat at relatively low temperatures, for producing both chilled water and cold, dehumidified air in variable quantities, as required by the load.     

Feasibility study of using agriculture waste as desiccant for air conditioning system

This research was aimed at investigating the feasibility of using dried agricultural waste as desiccant for an open cycle air conditioning system. The natural fibers are, therefore, intended to replace chemical desiccant such as silica gel, molecular sieves etc. The investigation was limited to Coconut coir (Cocos nucifera) and Durian peels (Durio zibethinus).Experimental results confirmed that dry coconut coir and durian peel can absorb 30 g and 17 g H₂O per 100 g dry product, respectively, from air at the average condition of 32°C and 75% relative humidity. The optimum airflow rate is about 84 and 98 m³/hr-100 g dry product, respectively. Therefore, the dry coconut coir is more suitable than the dry durian peel.Comparison between the dry coconut coir and silica gel showed that the average adsorption rate of coconut coir is less than that of silica gel by about 5 g/h-100 g dry product at an airflow rate of 84 m³/h and 60 min operating time. However, it is still an interesting option to replace silica gel in open cycle air conditioning system, as the decrease of average adsorption rate is rather small.The other extremely interesting advantage of coconut coir is that during moisture absorption the heat generated during the process is less important. That means the air leaves the coconut coir bed at a lower temperature compared to that with a silica gel. Therefore, the saving of cooling energy is much more important.     

Experimental investigation of the silica gel–water adsorption isotherm characteristics

In designing adsorption chillers that employs silica gel–water as adsorbent-adsorbate pair, the overriding objective is to exploit low temperature waste-heat sources from industry. This paper describes an experimental approach for the determination of thermodynamic characteristics of silica gel–water working pair that is essential for the sizing of adsorption chillers. The experiments incorporated the moisture balance technique, a control-volume-variable-pressure (CVVP) apparatus and three types of silica gel have been investigated, namely the Fuji Davison Type A, Type 3A and Type RD. As evidenced by the experimental results, the Henry-type equation is found to be suitable for describing the isotherm characteristics of silica gel–water working pair at the conditions of adsorption chiller. The regeneration of adsorbent depends on the correct allocation of temperature as well as the amount of regeneration time. From the experiments, the isotherm characteristics of silica gel–water in the low- to high-pressure regimes and hence, its isosteric heat of adsorption will be determined. Key parameters for optimizing the amount of heat recovery such as the cycle and switching time of chiller can also be implied from the measured results.     

Effect of internal cooling/heating coil on adsorption/regeneration of solid desiccant tray for controlling air humidity

Thermal performances of solid desiccant tray having internal cooling/heating coil for air humidity adsorption and desiccant regeneration are investigated. Three units of desiccant tray each of 48 cm × 48 cm cross‐sectional area and 2.5 cm thickness filled with silica gel are tested in a wind tunnel. For adsorption process, an air stream is flowing through the desiccant trays and the air humidity is captured by the silica gel. Approximately 10–40% of air humidity could be adsorbed more in case of the internal cooling. Besides, the outlet air temperature increases only slightly. In regeneration process, a hot air stream is used to repel the moisture in the silica gel. With the internal heating, the regeneration time is shorter compared with that without internal water heating. In addition, a correlation for calculating the adsorption/regeneration performance of the silica gel trays is developed and the results from the model agree well with the experimental data. Copyright © 2008 John Wiley & Sons, Ltd.     

Performance analysis of multistep sorption energy storage using compound adsorbents

The multistep sorption‐reaction cycle utilizes heat from several processes, such as absorption, dilution, crystallization reaction, and thermochemical reaction. So, it is very attractive to use multistep sorption technology to improve the performance of temperature transmitter, air conditioning, and heat pump. Different working pairs of silica gel/LiCl, activated carbon/LiCl multiwalled carbon nanotubes/LiCl, and multiwalled carbon nanotubes/CaCl₂ are tested and compared. The results show that the water uptake of these compound adsorbents varies with different salt mass fraction. The water uptake goes up dramatically at the crystallization and deliquescence point. Compared with the energy storage performance under the same working conditioning, the activated carbon/LiCl has the best performance, and the possible reason is that the activated carbon has the largest specific surface and the smallest average pore diameter.     

氯化钙/硅胶和氯化钙/凹凸棒土复合吸附剂的制备及性能对比

分别通过浸渍法和焙烧法制备了两种复合吸附剂氯化钙/硅胶和氯化钙/凹凸棒土。在温度40℃、相对湿度20%条件,氯化钙/硅胶复合吸附剂的吸水性能随样本中氯化钙含量的增加而增加。氯化钙/凹凸棒土的最佳焙烧条件为焙烧温度300℃,焙烧时间2 h。在相对湿度为20%,吸附时间分别为15,20 min时,氯化钙/凹凸棒土的SCP分别为140.26,128.92 W/kg,远大于同等条件下氯化钙/硅胶的SCP。两种吸附剂的吸附性能对比表明,氯化钙/凹凸棒土吸附剂由于其良好的吸水性能更加适用于低温驱动的吸附制冷机。     

Development and testing of a prototype of absorption heat pump system operated by solar energy

In this study, a prototype of an aqua–ammonia absorption heat pump system (AHP) using solar energy was investigated. The performance tests of the system were performed for the climate condition of Ankara in Turkey. The system has been designed operating with a parabolic slote type collector to obtain the required temperatures. In the experiments, high temperature water obtained from the collector was used as heat source needed for the generator. The system design configuration was analysed by using the experimental data. The effect of irreversibilities in thermal process on the system performance in AHP were determined. Thermodynamic analysis shows that both losses and irreversibility have an impact on absorption system performance. The study indicates which components in the system need to be improved thermally. This study will contribute the development of the system for the future use of solar-powered food preservation and commercial air conditioning.     

Optimized solar-powered liquid desiccant system to supply building fresh water and cooling needs

This paper studies the feasibility of using a solar-powered liquid desiccant system to meet both building cooling and fresh water needs in Beirut humid climate using parabolic solar concentrators as a heat source for regenerating the liquid desiccant. The water condensate is captured from the air leaving the regenerator. An integrated model of solar-powered calcium chloride liquid desiccant system for air dehumidification/humidification is developed. The LDS model predicted the amount of condensate obtained from the humid air leaving the regenerator bed when directed through a coil submerged in cold sea water. An optimization problem is formulated for selection and operation of a LDS to meet fresh water requirement and air conditioning load at minimal energy cost for a typical residential space in the Lebanon coastal climate with conditioned area of 80 m² with the objective of producing 15 l of fresh drinking water a day and meet air conditioning need of residence at minimum energy cost. The optimal regeneration temperature increases with decreased heat sink temperature with values of 50.5 °C and 52 °C corresponding to sink temperatures of 19 °C and 16 °C.     

An efficient solar-powered adsorption chiller and its application in low-temperature grain storage

A novel solar-powered adsorption cooling system for low-temperature grain storage has been built, which consists of a solar-powered water heating system, a silica gel–water adsorption chiller, a cooling tower and a fan coil unit. The adsorption chiller is composed of two identical adsorption units, each of them containing an adsorber, a condenser, and an evaporator/receiver. The two water evaporators have been incorporated into one methanol evaporator by the use of the concept of a gravity heat pipe. In order to improve the system efficiency and achieve continuous cooling production, the adsorbers are operated out-of-phase, and heat and mass recovery processes have been used. During the period from July to September of 2004, the system was put into experimental operation to cool the headspace (i.e., the air volume above the grain) of a grain bin. Three months of operation showed promising performance. The chiller had a cooling power between 66 and 90 W per m² of collector surface, with a daily solar cooling coefficient of performance (COP_solar) ranging from 0.096 to 0.13. The electric cooling COP was between 2.6 and 3.4.     

Heat-pump/energy-store using silica gel and water as a working pair

The possibilty of using silica gel and water as a reversible pair, in a thermochemical heat-pump/energy-store has been studied theoretically and experimentally during both heating and cooling modes. With silica gel absorbing water by 25±2% of the dry silica gel's weight, the heat of adsorption and the heat of wetting of 2712.43±30 kJ/kg SiO₂ and 94.43± 15 kJ/kg SiO₂ have been achieved respectively. The concentration rate for the two reaction pair was investigated and a general relationship that governed the adsorption rate with time has been deduced.