Operational performance of a novel fast-responsive heat storage/exchanging unit (HSEU) for solar heating systems

RENEWABLE ENERGY

卷:151

Article

Fan, Yi¹  Zhao, Xudong¹  Li, Jing¹  Cheng, Yuanda²  Badiei, Ali¹  Zhou, Jinzhi¹  Yu, Min¹  Li, Guiqiang¹  Du, Zhenyu²  Ji, Jie³  Zhu, Zishang¹  Ma, Xiaoli¹  Bai, Huifeng⁴  Myers, Steve¹ 

[1] Univ Hull, Sch Engn & Comp Sci, Kingston Upon Hull HU6 7RX, N Humberside, England

[2] Taiyuan Univ Technol, Coll Environm Sci & Engn, Yingze West St 79, Taiyuan 030024, Shanxi, Peoples R China

[3] Univ Sci & Technol China, Dept Thermal Sci & Energy Engn, Hefei 230026, Anhui, Peoples R China

[4] Shanxi Zhonglv Environm Protect Grp Co LTD, Taiyuan, Shanxi, Peoples R China

关键词: Fast response;    Heat storage/exchanging unit;    Response time;    Space heating;    Solar thermal efficiency;    Heat transfer coefficient;   

DOI  :  10.1016/j.renene.2019.11.007

来源: Elsevier

【 摘 要 】

In order for a solar heating system to provide heat immediately after sunrise, a fast response is needed to the heat demand of a serviced space. The majority of existing solar heating systems have a slow response time due to the large volume of water stored in the heat storage/exchanger unit (HSEU). This leads to a slow heat delivery cycle, which results in discomfort for the occupants and thus creates a huge barrier to the wide deployment of solar heating systems. To overcome this critical issue, a novel interactive heat storage/exchanging unit (HSEU) employing a double-tank configuration was developed. Unlike conventional HSEUs, which have a single tank acting as the heat storage and exchanging unit, the new HSEU is comprised of a small tank for heat exchange combined with a large tank for heat storage. The small tank enables fast transfer of solar heat to the heating loop fluid without having to heat up the large volume of water in the entire HSEU tank, whilst the large tank is used to store and exchange heat between itself and the small tank using a temperature-oriented control mechanism. To test the proposed design, the heat transfer between the first (solar loop) and second (heating loop) fluids, the heat and mass transfer between the small and large tank and the associated operational strategy were investigated experimentally and theoretically for comparison. A conventional single tank HSEU requires around 120 min to deliver heat to a served space, whilst the new interactive double-tank HSEU can provide heat to the served space in around 20 min, thus creating a heating system which can respond significantly faster than traditional systems. The investigation of the heat exchange effect between the solar and heating loop fluids showed that the new HSEU achieved a convective heat transfer coefficient of as high as 391 W/m(2).K, which is 551% higher than that of a conventional tank. As a result, the solar thermal efficiency of the solar panel-array in the new HSEU based system was increased by 7.5% compared to conventional HSEU based systems. (C) 2019 Elsevier Ltd. All rights reserved.

【 授权许可】

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