【作者】 韩晶；

【导师】 王宪恩；

【作者基本信息】 吉林大学 ， 环境工程， 2004， 硕士

【摘要】 太阳能作为一种能源和动力进行应用，已有300多年历史，但在上个世纪70年代以前，太阳能技术的发展比较缓慢，利用范围有限。而70年代初，世界上出现了开发利用太阳能的热潮，研究领域不断扩大，出现了真空集热管、非晶硅太阳电池、太阳能发电等等一批新成果，太阳能热水器、太阳电池等产品开始实现商业化，但规模比较小，经济效益不理想。太阳能开发利用经历的时间比较长，主要原因是因为太阳能的开发利用难度较大。由于大量燃烧不可再生能源，造成了全球性的环境污染和生态环境的破坏，对人类的生存和发展构成威胁。一九九二年联合国在巴西召开“世界环境与发展大会”，通过了《里约热内卢环境与发展宣言》等一系列重要文件，把环境和发展纳入一个统一的框架，确立了可持续发展的模式，世界各国加强了清洁能源技术的发展。太阳能作为一种取之不尽、用之不竭的新型清洁能源，它的开发利用越来越受到世界范围的广泛关注，太阳能与环境结合起来，使太阳能的利用迎来了一个新的发展阶段。我国也相应制定了《中国21世纪议程》，进一步明确了太阳能为重点发展项目。目前在太阳能的应用中，太阳能热水供应应用的最为普遍，其系统形<WP=49>式主要有：家用太阳能热水器、集中式太阳能热水供应、太阳能开水供应等。集中式太阳能热水供应系统在运行时需要补充热源，目前补充热源主要是以燃油炉或燃气炉为主，也有用电进行加热的。这几种补充热源，具有系统初投资大，设备闲置时间长等缺点。我国大部分地区冬季需要采暖，将采暖系统的回水作为太阳能系统的补充热源，接至太阳能系统的储热水箱中，这样两个系统可以联合运行，见图1。采暖热媒的设计温度一般为95~70℃。实际运行时，随着室外气温的变化，供水温度会发生改变，相应的回水温度也在发生变化，对于与外网直接连接的一般散热器热水采暖系统，进行质调节时，管网的回水温度可按下式计算 <WP=50> （1）式中th′为任一室外气温下，供热管网的供、回水温度，℃；tg、th为设计条件下的供、回水温度，℃；tn为冬季室内计算温度，℃；tw为冬季室外空气温度，℃；twj为采暖室外空气计算温度，℃；B——与散热器类型有关的实验系数。以长春市为例：采暖室外空气计算温度为－23℃，室内空气设计计算温度为18℃， 采用大60型散热器，可查得B=0.28，将参数代入式（1）计算，结果表明回水温度在40.3~70℃范围内变化（若有量调节时回水温度变化范围会增大几度），在此取35~70℃分析。由《建筑给水排水设计规范》可知，热水供应系统的设计温度一般为60~75℃，另外，当热水供应系统只供淋浴和盥洗用水，不供洗涤盆用水时，配水点最低水温可不低于40℃。 这为采暖系统和太阳能系统的有机结合提供了有利条件。在采暖期，图1中阀门1、3、4打开，阀门5关小，阀门2关闭，热水从水箱上部取用（储热水箱在实际运行时，在扰动较小的情况下，上部和下部的水温相差接近10℃）。在太阳能系统得热量越少的月份，采暖系统的回水温度越高，太阳能系统可获得的补充热量越多。对于水—水换热，其换热温差可取10℃，采暖系统在实际运行时，很少能达到设计工况，回<WP=51>水温度能达到60℃就算很高了，因而联合运行系统的热水供应最高温度应在70℃左右；另外当采暖系统回水温度在35℃时，基本在采暖的初期和末期，此时太阳能系统的得热量有节余，采暖系统起冷却作用，联合运行系统的热水供应温度应在45℃左右，即实际运行时，采暖期联合运行系统的热水供应温度在45~70℃的范围变化，能够满足热水供应的要求。在非采暖期，采暖系统停止运行，而此时太阳能系统的得热量有节余，储热水箱中的水温高于热水供应的设计温度，因此，图1中阀门2打开，阀门1关闭，取用水箱下部温度较低的热水。不同系统的经济效益可按照费用年值法进行分析比较，比较时都以系统每获得1GJ的热量所需费用为基准，计算公式如下：每平方米建筑面积的费用年值Z可按式（2）计算： （2）式中Z为费用年值，元/m2·年；C为热水供应系统的年运行费用，元/m2·年；K为热水供应系统的工程投资，元/m2；n为热水供应设施（设备）的种类数；x为投资效果系数，1/年。系统每获得1GJ的热量所需的费用Z1可按式（3）计算： <WP=52> （3）式中Z1`为系统每获得1GJ的热量所需的费用，元/GJ；Q为每平方米建筑面积每年从系统中获得的热量，GJ/ m2·年。在我国七个热能区中，除南方区和西南区之外，其余五个区均需采暖，在这五个区内分别取一个城市，即长春（东北区）、北京（华北区）、呼和浩特（黄土丘陵区）、乌鲁木齐（西北干旱区）和拉萨（青藏高原），按式（2）、（3）进行计算，结果表明：1)青藏高原区利用太阳能系统进行热水供应的费用是最少的，而且比其它地区低很多，比费用最高的东北地区（99.26元/GJ）低34.82%。2）在我国的主要采暖地区，热水供应的热负荷在采暖期与非采暖期相差不大，但采暖期所需集热器面积均比非采暖期大一倍以上。这样联合运行系统集热器面积若按采暖期平均负荷确定，在采暖期无需额更多还原

【Abstract】 It has been more than 300 years since solar energy was first used as a source of energy and power. However, the development of solar energy technique had been slow and the range of its application rather limited before the 1970s. Since the early 1970s, there has been a continuing global effort in the development of solar energy. The solar energy related research area has been constantly expanding with many new technologies as the result during the progress, such as vacuum heat collecting pipe, amorphous silicon solar battery, solar electricity generation and etc. Some products, such as solar water heater and solar battery, have been commercialized, but with limited application scale and less ideal economical benefit. The development of a utilization of solar energy usually takes rather long to mature, primarily because of the difficulty involved in the development process. The mass consumption of non-renewable energy resources results in worldwide environmental pollutions and damages to the ecological environment, which has become the threat to the life and well being of human beings. In 1992 the United Nations held the Conference on the International Environment and Development in Brazil, and a number of important documents, including “Declaration of Rio de Janeiro Environment and Development” have been produced by the conference, which have brought environment and development into a united frame, and set up a sustainable developing model. Countries all over the world strengthen the technologies in the development of green energy. As an inexhaustible clean energy source, solar energy is gaining more and more attentions worldwide. Concerted development of solar energy utilization and environment protection has led to a new stage of solar energy technologies. Our country has also <WP=55>established correspondingly the “Agenda of the 21st Century China”, where solar energy source is considered as a key development area. Currently, the most popular application of solar energy is in hot water supply. This mainly includes home solar energy hot water heater, centralized solar energy hot water supply, solar energy boiling water supply system and etc.. Centralized solar energy hot water supply system needs supplementary heat input during operation. At present, oil burner or gas burner are the main supplementary heat supplies, though electricity is used in some cases as well. All the above supplementary heating systems have the drawbacks of large infrastructure investment, long idle period and etc.. In our country house-warming heat supply is needed in most regions during the winter backwater. If the returning water in the heating system is connected to the hot water storage tank in the solar energy system as the supplementary heat source, the two systems can be run in a combined fashion (as shown in Fig 1). The designed temperature for heating media is typically around 95~70℃. However, in <WP=56>practice, the temperature of the supply water varies with outdoor temperature, and thus the temperature of the return water varies accordingly. As to a common radiator of the heating system, which is directly connected to the outside network, during the regulation, the temperature of the return water in the pipe network can be calculated as following: （1）where th′(in unit of ℃) is the temperature of supply water or return water under any outdoor temperature; tg、th (in unit of ℃) are the temperatures of supply water and return water respectively under designed conditions; tn is the calculated indoor temperature during winter time; twj is the calculated outdoor air temperature; B is a radiator-related empirical parameter. Here Changchun city is used as an example. The calculated air temperature outside of the heating room is －23℃，and the calculated indoor air temperature is 18℃， and if the L-60 type of radiator is used，from tabulated data it can be found that B=0.28. Applying all the above parameters to Formula 1, the result shows that the return water temperature varies in the更多还原