冷管型太阳能制冷系统

太阳能吸附式制冷作为一种绿色环保型的制冷技术具有良好的应用前景。本文分析了一种吸附床可直接吸收太阳能的、自身完成集热与制冷的玻璃管型太阳能吸附式制冷管,并介绍了以该冷管为基础的太阳能制冷系统。     

一种新颖的太阳能制冷管及其性能实验研究

一种新颖结构的太阳能吸附制冷管,其吸附床由一种具有高强度,高吸附性能和导热性能,并对太阳能具有高吸收率的复合吸附剂块组成,与已有的太阳能制冷系统相比,每根冷管生成一个制冷系统,结构简单,密封性好,同时吸附床可直接吸收太阳辐射,提高了对太阳能的有效利用。实验表明,在未采用专门的集热装置,吸附床向阳面温度仅为７５℃左右的情况下,冷管的性能,系数可达８％左右。     

太阳能冷管吸附制冷的数值模拟与实验研究

介绍了太阳能冷管应用吸附制冷的运行机理并建立了太阳能冷管运行周期的数学模型,求解得出吸附 床温度、中芯管壁温度、蒸发器壁面温度等参数随时间变化的关系。进行了太阳能冷管的实验研究,在环境温 度为:36-28℃,冷管周围风速:0．5m／s的条件下,太阳能冷管制冷持续时间为13h,冷管蒸发器温度最低可达 18℃,实验测量值与理论计算结果吻合的较好。     

太阳能吸附式制冷技术进展综述

介绍了太阳能吸附式制冷技术的原理与特点，从吸附剂一制冷剂工质对、系统循环方式以及吸附床三个方面详细说明了吸附式制冷技术的进展。通过综合分析指出，优化系统的设计，尤其是对系统关键部件，如吸附床、冷凝器、蒸发器的优化设计，对太阳能吸附式制冷系统的性能非常重要；其次，应加强对性能稳定、操作简便的无阀系统的研究，同时加大对太阳能吸附式制冷与建筑一体化的研究力度，使之符合建筑一体化的要求。最后分析了太阳能吸附式制冷技术的发展前景。     

翅片管整体传热传质强化的太阳能吸附式制冷系统性能研究

针对太阳能金属管式吸附床传热传质存在的不足,采用增加吸附管传热翅片及增大传质通道的方法,提出一种整体强化传热传质的新型翅片管设计方法,分别设计两种结构形式的太阳能吸附集热器,建立采用活性炭-甲醇为工质对的太阳能吸附式制冷系统。实验表明,采用吸附管横放、两端分别连接汇流导管形式的太阳能翅片管式吸附集热床可明显改善系统制冷性能,其吸附制冷效率是采用吸附管纵向放置、从翅片管上部通过导管连接到汇流导管的吸附床的太阳能吸附式制冷系统的3.56倍。采用性能较好的吸附床可构建太阳能吸附式制冷系统,并在晴朗无云、晴天有时有云、多云辐射强烈及多云辐射微弱4种典型天气情况下,进行吸附制冷系统运行特性和制冷性能实验研究,结果表明前三种天气条件下吸附床维持较高温度(≥80℃)超过4 h,制冷剂解吸较为充分,均产生制冰效果,制冷效率较高,COP最高达0.129;在多云太阳辐射微弱天气条件下,虽然吸附床维持在较高温度(≥80℃)时间不到2 h,但COP可达0.039,体现出该翅片管式吸附床良好的天气适应性。     

非跟踪聚焦型太阳能冷管及其性能研究

该文在提出了真空集热的太阳能冷管的基础上，引入非跟踪聚焦的复合抛物面聚光器(CPC)，以增强冷管吸附床对太阳辐射的吸收，提高单管制冷量与制冷系数。从理论上分析并设计了与太阳能冷管相配的CPC反光板，并对其半接受角、平均反射因子、光学效率和聚焦比等参数之间的关系进行了分析。理论与实验结果表明，CPC反光板与该太阳能冷管结合，可以提高吸附床温度，增加脱附量。与轧花铝的平板型相比，非跟踪聚焦型太阳能冷管的制冷量提高了60～67％，COP提高了16～21％。     

太阳能吸附式制冷系统的研究现状与发展前景

从工作原理、工质对的选择、吸附床的设计、经济性分析及应用几方面,对太阳能吸附式制冷系统进行了详细的综述性分析。由于太阳能转换率低和集热器价格昂贵,目前太阳能吸附式制冷系统存在的主要问题是制冷性能较低、初投资成本大,所以,提高制冷性能、降低成本是太阳能吸附式制冷系统实现商业化和产业化的关键所在。通过选取合适的工质对、强化吸附床的传热传质性能,可有效提高系统的制冷系数,推进其工业化应用。     

固体吸附式冷管循环工作过程的动态模拟与分析

针对余热驱动吸附式冷管单元(直径16mm,总长1020mm)制冷循环过程的变压吸/脱附特性,采用线性驱动力(LDF)模型,建立了动态的传热传质数学模型。对吸附式冷管的主要部件——吸附器和冷凝/蒸发器在加热解吸和冷却吸附不同阶段的工作过程,分别建立了耦合的动态方程。对所提出的模型进行分析和合理简化后,利用数值方法对模型进行了求解,获得了冷管单元吸附器、冷凝/蒸发器的循环工作参数的动态变化规律,计算结果与实验结果较好地吻合。为吸附式冷管单元及其组合式制冷系统进一步的优化设计和实用化的改进研究提供了重要参考。     

太阳能驱动实现制冷的研究及其应用

本文提出了利用太阳能驱动实现制冷是一门节能环保技术，重点分析和论述了太阳能驱动实现制冷的几种主要方法．即利用太阳能光一电转换实现制冷、太阳能吸收式制冷、太阳能吸附式制冷和太阳能喷射式制冷。指出太阳能驱动实现制冷的研究具有广阔的应用前景。     

聚光连续型高效智能吸附式空调及其强化传热设计浅析

基于双床吸附连续制冷的理论,提出了一种聚光连续型高效智能吸附式空调系统,将聚光光伏技术和吸附式制冷技术相结合,形成冷、热、电联产一体化的新思路。系统设计围绕连续回热型的吸附制冷循环、太阳能聚光器、光伏电池板3个重要方面,提出太阳能3个层次优化利用,进一步强化传热和提高能源利用率,为丰富发展吸附式空调系统理论、低成本高效利用太阳能提供技术支持。     

Performance of a dual-purpose solar continuous adsorption system

A conceptual design and performance of a dual-purpose solar continuous adsorption system for domestic refrigeration and water heating is described. Malaysian activated carbon and methanol are used as the adsorbent–adsorbate pair. The heat rejected by the adsorber beds and condensers during the cooling process of the refrigeration part is recovered and used to heat water for the purpose of domestic consumption. In a continuous 24-h cycle, 16.9 MJ/day of heat can be recovered for heating of water in the storage tanks. In the single-purpose intermittent solar adsorption system, this heat is wasted. The total energy input to the dual-purpose system during a 24-h operation is 61.2 MJ/day and the total energy output is 50 MJ/day. The latter is made up of 44.7 MJ/day for water heating and 5.3 MJ/day for ice making. The amount of ice that can be produced is 12 kg/day. Using typical value for the efficiency of evacuated tube collector of water heating system of 65%, the following coefficient of performances (COP's) are obtained: 44% for adsorption refrigeration cycle, 73% for dual-purpose solar water heater, 9.1% for dual-purpose solar adsorption refrigeration and 82.1% for dual-purpose of both solar water heater and refrigerator.     

Performance study of a high efficient multifunction heat pipe type adsorption ice making system with novel mass and heat recovery processes

The purpose of this paper is to present the performance analysis of a multifunction heat pipe type adsorption ice maker with activated carbon–CaCl₂ as compound adsorbent and ammonia as refrigerant. For this test unit, the heating, cooling and heat recovery processes between two adsorbent beds are performed by multifunction heat pipes. A novel mass and heat recovery adsorption refrigeration cycle is developed. When mass recovery process is implemented before heat recovery process, the performance of the cycle with novel mass and heat recovery processes is much better than that for the cycle with the conventional mass and heat recovery processes. The experimental results show that the former cycle can increase the coefficient of performance (COP) and specific cooling power (SCP) by more than 17% compared with the latter cycle. In comparison with the basic adsorption cycle, the mass and heat recovery cycle can enlarge the cycled refrigerant mass and reduce the power consumption of boiler; the COP and SCP were improved by more than 11% when the mass recovery time was 20 s, while at the optimal mass recovery time of 40 s, the COP improvements for conventional and novel mass and heat recovery cycles are 43.8% and 68.7%, respectively. It was concluded that the novel mass and heat recovery processes are more beneficial to improve the performance of adsorption refrigeration system in comparison with the conventional mass and heat recovery processes.     

Study of a solar powered solid adsorption–desiccant cooling system used for grain storage

A hybrid solar cooling system, which combines the technologies of rotary desiccant dehumidification and solid adsorption refrigeration, has been proposed for cooling grain. The key components of the system are a rotary desiccant wheel and a solar adsorption collector. The former is used for dehumidification and the later acts as both an adsorption unit and a solar collector. The heating load from sunshine can thus be reduced to a greater extent since the solar adsorption collector is placed on the roof of the grain depot. Compared with the solid adsorption refrigeration system alone, the new hybrid system performs better. Under typical conditions, the coefficient of performance of the system is >0.4 and the outlet temperature is <20°C. It is believed that the system can be used widely in the regions with abundant solar resources due to such advantages as environmental protection, energy saving and low operation costs. Additionally, some parameters, for example, ambient conditions, the effectiveness of the heat exchanger and evaporative cooler, mass air-flow rate, etc., which affect system performance, are also analyzed.     

新型平板式太阳能冷热联供装置

在积累了太阳固体吸附式制冷循环研究的基础上，与现有的平板式太阳热水器制造技术紧密结合，提出了平板式太阳冷热联供循环方式，并在实验室内成功地制作了实物样机。该装置能有效地回收太阳固体吸附式制冷不中吸附床的显热及吸附热，且操作简便。实验结果有效地支持了所提出的设想，为太阳固体吸附式制冷的实用化应用打下了良好基础。     

Comparative study of different solar cooling systems for buildings in subtropical city

In recent years, more and more attention has been paid on the application potential of solar cooling for buildings. Due to the fact that the efficiency of solar collectors is generally low at the time being, the effectiveness of solar cooling would be closely related to the availability of solar irradiation, climatic conditions and geographical location of a place. In this paper, five types of solar cooling systems were involved in a comparative study for subtropical city, which is commonly featured with long hot and humid summer. The solar cooling systems included the solar electric compression refrigeration, solar mechanical compression refrigeration, solar absorption refrigeration, solar adsorption refrigeration and solar solid desiccant cooling. Component-based simulation models of these systems were developed, and their performances were evaluated throughout a year. The key performance indicators are solar fraction, coefficient of performance, solar thermal gain, and primary energy consumption. In addition, different installation strategies and types of solar collectors were compared for each kind of solar cooling system. Through this comparative study, it was found that solar electric compression refrigeration and solar absorption refrigeration had the highest energy saving potential in the subtropical Hong Kong. The former is to make use of the solar electric gain, while the latter is to adopt the solar thermal gain. These two solar cooling systems would have even better performances through the continual advancement of the solar collectors. It will provide a promising application potential of solar cooling for buildings in the subtropical region.     

The effects of operation parameter on the performance of a solar-powered adsorption chiller

A solar-powered adsorption chiller with heat and mass recovery cycle was designed and constructed. It consists of a solar water heating unit, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. The adsorption chiller includes two identical adsorption units and a second stage evaporator with methanol working fluid. The effects of operation parameter on system performance were tested successfully. Test results indicated that the COP (coefficient of performance) and cooling power of the solar-powered adsorption chiller could be improved greatly by optimizing the key operation parameters, such as solar hot water temperature, heating/cooling time, mass recovery time, and chilled water temperature. Under the climatic conditions of daily solar radiation being about 16–21 MJ/m², this solar-powered adsorption chiller can produce a cooling capacity about 66–90 W per m² collector area, its daily solar cooling COP is about 0.1–0.13.     

真空集热型太阳能固体吸附式制冷的理论研究

为提高太阳能吸附制冷系统的集热性能。提出了采用真空集热管式吸附床的太阳能固体吸附制冷系统，并对选择吸收式和直接吸热式的真空集热制冷系统分别进行了理论分析与计算模拟。这两种系统均具有较高的制冷性能，前者宜以沸石-水为制冷工质对，而后者则宜采用活性碳-甲醇工质对。分析了工作参数对这两种真空集热型制冷系统的影响，并对系统结构进行了优化研究。     

A three-dimensional non-equilibrium model for an intermittent adsorption cooling system

Intermittent adsorption cycles, driven by low temperature heat, like solar heat, instead of electricity or natural gas, can achieve substantial fossil energy savings. In this paper, the mathematical model for the coupled heat and mass transfer in the adsorber of an intermittent adsorption cooling system is set up. The model includes four submodels: heat transfer in heating/cooling fluids, heat transfer in the metal tube, heat transfer in the fins, and heat and mass transfer in the adsorbent. The model for the heat and mass transfer in the adsorbent is a three-dimensional non-equilibrium model which takes into account both the internal and the external mass transfer resistance in the adsorbent. An experiment has been done to validate the model. With some modifications, the model can be used in system optimization and design of adsorption cycles driven by solar energy or waste heat.     

基于平行流铝扁管吸附床传热性能的模拟研究

吸附床是吸附式制冷系统的关键部件。吸附床的换热能力对吸附式制冷系统的各项性能有显著影响。文章针对应用于吸附床的传统换热器和扁管换热器的不足之处,设计出一种新型平行流铝扁管吸附床,并建立了该吸附床的二维传热模型,以温度随时间的变化情况为分析指标,分析翅片的间距、高度、厚度,以及吸附剂体积分数等因素对吸附床传热性能的影响,从而优化调整吸附床的结构,提高其换热性能。分析结果表明:当翅片高度约为70 mm时,吸附床的换热能力达到峰值;当翅片厚度大于1.5 mm时,翅片厚度的增加对吸附床传热性能的影响比较微弱;当吸附剂体积分数由0.25逐渐增大至0.45时,吸附剂的等效传热系数约增加了50%。