Vacuum enclosures for solar thermal panels Part 2: Transient testing with an uncooled absorber plate
Vacuum enclosures for solar thermal panels Part 2: Transient testing with an uncooled absorber plate
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DOI：
10.1016/j.solener.2018.10.063
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发表时间：
2018-11
期刊：
影响因子：
6.7
通讯作者：
Farid Arya;Roger Moss;Trevor J. Hyde;Stan Shire;P. Henshall;P. Eames
中科院分区：
文献类型：
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作者：
Farid Arya;Roger Moss;Trevor J. Hyde;Stan Shire;P. Henshall;P. Eames
在平板太阳能集热器中的太阳能吸收器周围产生真空（<1Pa）可以通过最小化吸收器板和玻璃盖之间的气体传导和对流来提高效率。高性能和建筑上有吸引力的平板太阳能集热器是吸引建筑业主和设计师提供清洁和可再生能源的成本有效地生产通过建筑物的立面。这两部分的文件介绍了建筑技术和热性能的两个真空外壳，制造在阿尔斯特大学，作为原型组件的真空平板太阳能集热器。在0.0033 Pa、17 Pa和大气压三种条件下对外壳进行了测试。第一个外壳由两块玻璃板组成，密封到边缘间隔物上，并由一排支撑柱在规则的正方形网格上隔开，形成一个狭窄的真空空间。第二个外壳，包含一个未冷却的铜板，代表太阳能热吸收器。本文第一部分描述了第一个外壳的制造技术，并将热箱量热计和红外热成像测试的结果与数值和分析预测进行了比较，第二部分描述了第二个外壳的太阳模拟器测试，该外壳包含一个未冷却的铜板。在太阳模拟器下进行的测试表明，与低真空（17 Pa）和大气压测试相比，高真空测试（0.0033 Pa）的停滞温度更高。瞬态响应数据的热传递模型的曲线拟合表明，辐射和气体传导接近预测。模拟结果与瞬态响应和稳态渐近板温度非常吻合。
Creating a vacuum (<1 Pa) around a solar absorber in a flat plate solar thermal collector can increase efficiency by minimising gaseous conduction and convection between the absorber plate and the glass cover. High performance and architecturally attractive flat plate solar thermal collectors are appealing to building owners and designers for supplying clean and renewable energy cost effectively produced via the façade of the building.This two part paper describes the construction techniques and thermal performance of two vacuum enclosures, fabricated at Ulster University, as prototype components for evacuated flat plate solar collectors. The enclosures were tested at three conditions: 0.0033 Pa, 17 Pa and atmospheric pressure. The first enclosure consisted of two glass panes, sealed to an edge spacer and separated by an array of support pillars on a regular square grid to form a narrow evacuated space. The second enclosure, incorporated an uncooled copper plate to represent a solar thermal absorber. Part 1 of this paper has described the fabrication techniques and compared results from hot-box calorimeter and IR thermography testing of the first enclosure with numerical and analytical predictions.Part 2 describes solar simulator testing of the second enclosure which incorporated an uncooled copper plate. Testing under a solar simulator showed a higher stagnation temperature in the high vacuum test (0.0033 Pa) in comparison with the low vacuum (17 Pa) and atmospheric pressure tests. Curve fitting of a heat transfer model to the transient response data demonstrated that radiation and gas conduction were close to predictions. Simulated results were in close agreement with both the transient response and the steady-state asymptotic plate temperatures.