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太阳能热水器智能控制系统的设计与仿真
Hu Runqing
Journal of Beijing university
Bei Jing 855000
摘 要：在能源日益紧张的今天，电热水器，饮水机和电饭煲之类的家用电器在保温时，由于其简单的温控系统，利用温敏电阻来实现温控，因而会造成很大的能源浪费。但是利用AT89C52单片机为核心，配合温度传感器，信号处理电路，显示电路，输出控制电路，故障报警电路等组成的控制系统却能解决这个问题。单片机可将温度传感器检测到的水温模拟量转换成数字量，并显示于LED数码管上。该系统具有灵活性强，易于操作，可靠性高等优点，将会有更广阔的开发前景。
关键词：传感器；A/D转换；DS18B20
1 在中国快速发展的太阳能热水器
1.1 发展阶段
中国的太阳能光热应用从20世纪70年代开始发展。在20世纪80年代后期，引进加拿大生产铜 - 铝复合材料的吸收体为平板TION线集电极和自行设计的生产线的发展阳极氧化选择性涂层，中国开始制造平板太阳能热水器。但由于成本和兼容性的问题，进展缓慢，如在冬季。重大突破是在20世纪90年代中得来的技术和生产全玻璃真空管，使中国自行设计的发展真空管生产线，并开始批量生产全玻璃真空管太阳能热水器。所有这些成就在科学和研究方面投入生产贡献的生产力的不断提高，太阳能集热器和全玻璃真空集热管和热水器热管和成本的减少。它提供了巨大的动力，使中国太阳能热利用产业的产业化。随着经济的发展，城市的需求，中国农村居民的生活和洗浴大幅增加。与电热水器和燃气热水器热水器，太阳能热水器成为供应热水供国内使用的主要产品之一。
1.2 稳定快速的增长市场
20世纪90年代以来，中国太阳能热水器市场的在十多年保持了较快的增长。中国太阳能的年产覆盖量从2000年的6.1万平方米发展的2009年的42万平方米，增长率为24%。王振滔琛（2010年）。累计安装太阳能热水器从2000年的26平方米增加到2009年的145万平方米，每年的增长速度为21％。特别是由于可再生能能源法“正式生效后，国家有关更新的发展能源的政策，政府的在新农村建设和地方的建筑上强制安装太阳能热水器。太阳能热水器应用已经大大的推广。从2006年到2009年间，平均每年增长太阳能热水器的销售率维持在33％，而总库存平均每年增长17％，这标志着太阳能热水器的应用已经达到了新的高度。图1代表了中国太阳能热水器年产量从1998年至2009年的增长速度，表1盘点中国的太阳能热水器，1998年至2009的速度增长。
figure 1
2 温度检测电路设计
温度检测部分是实现温度智能控制的重要环节，只有准确地检测出温度，才能通过软件实现辅助加热。其性能的好坏直接影响系统的性能，对于温度检测，本设计用的是温度传感器DS18B20。
DSl8B20数字温度计提供9位(二进制)温度读数,指示器件的温度信息经过单线接口送入DSl8B20或从DSl8B20送出.因此从主机CPU到DSl8B20仅需一条线(和地线)。DSl820的电源可以由数据线本身提供而不需要外部电源。因为每一个DSl8B20在出厂时已经给定了唯一的序号，因此任意多个DSl8B20可以存放在同一条单线总线上。这允许在许多不同的地方放置温度敏感器件。DSl820的测量范围从-55℃到+125℃增量值为0.5，可在ls(典型值)把温度变换成数字。
3 模拟/数字转换电路
A/D转换是将传感器输入的模拟量转换成数字量送入单片机内。本设计采用的是ADC0832。一般情况ADC0832与单片机的接口应为4条数据线，分别是CS、CLK、DO、DI。但由于DO端与DI端在通信时并未同时有效并与单片机的接口是双向的，所以电路设计时可以将DO和DI并联在一根数据线上使用。当ADC0832未工作时其CS输入端应为高电平，此时芯片禁用，CLK和DO/DI的电平可任意。当要进行A/D转换时，须先将CS端置于低电平并且保持低电平直到转换完全结束。此时芯片开始转换工作，同时由处理器向芯片时钟输入端CLK提供时钟脉冲，DO/DI端则使用DI端输入通道功能选择的数据信号。在第1个时钟脉冲到来之前DI端必须是高电平，表示启动位。
4 LED显示电路
在单片机系统中，常用的显示器有发光二极管显、荧光管显示器、数码管显示和液晶显示。近年来，也开始使用简易的CRT接口，显示一些汉字及图形。发光二极管显示分为固定段显示和可以拼装的大型字段显示，此外还有共阳极和共阴极之分等。
LED显示块是由无数发光数码管组成的显示器，数码管的每一个数码管段是一只发光二极管，当发光二极管导通时，相应的一个点或一个笔画发光，控制发光二极管发光组合，可以显示出所需字符，有7段和字段之分。这种显示块有共阳极和共阴极两种。共阴极LED显示块的发光二极管的阴极连接在一起，通常此公共阴极接地，当某个发光二极管的阳极为高电平时，发光二极管点亮，相应的段被显示。同样，共阳极LED显示块的发光二极管的阳极连接在一起，通常此公共阳极接正电压。当某个发光二极管的阴极接低电平时，发光二极管点亮，相应的段被显示。LED的显示方式有静态显方式和动态显示方式。
5 系统的工作原理
利用DS18B20传感器对水箱温度进行实时监控，当检测到水温信号后，反馈到单片机上，并用数码管动态扫描方式显示当前的水温和预设的水温。电极方式测量水位，当水没过各个档次的电极时，利用水的弱导电性，电压在3伏左右，经过斯密特触发器后变成了0V，水位指示灯两端有了电压差而被点亮；反之，没接触水电压在0伏左右，经过斯密特触发器后变成了5V，水位指示灯两端没有电压差，即没有电流通过，指示灯灭。当出现缺水状态（水位低于20％）时，蜂鸣报警，所有的水位指示灯熄灭。利用隔离电路来对系统进行自动加热和上水，具体的条件由软件程序来控制，从而实现智能性。
6 中国太阳能热水器行业中的经验和特点
6.1 没有激励政策已经形成商业运转
无论是市场还是厂家太阳能热水器在中国都没有享受奖励的财政和税收政策。与电热水器和燃气热水器相比，太阳能热水器有没有偏好。唯一的太阳能热水器企业由当地政府列为高新技术企业，可以享受高新技术企业的优惠政策。市场的需求是在中国太阳能热水器市场的发展背后的驱动力，所以它是，促进了市场的发展在中小城市和农村地区的居民对热水的需求，但没有激励政策的国家。满足居民太阳能热水器洗澡，高性价比的需求。这是其快速发展的动力。太阳能热水器成为人在一起电力和燃气热水器提供生活热水的主要产品之一，并逐渐成为主导产品，因为它的高性价比。初始投资的太阳能热水器比电热水器和燃气热水器相比，太阳能热水器不消耗燃料，其每年的运营成本低，所以在其生命周期内的平均成本只有其他两种类型的水加热器的1/3。由于声音的性价比，市场份额的太阳能在中国热水器不断增加，从2000年的15.2％至57.2％，太阳能热水器已成为中国市场上的主流产品。
6.2 真空集热管热虹吸系统
中国的主流产品是真空集热管热虹吸系统与先进的间接和加压的产品在世界上的比较，这种类型的结构简单，技术要求低，生产成本低的优势。此外，经过多年的努力，这种模式的生产和市场已经达到一定的规模，产品的质量保证经济效率高，产品符合目前中国市场的需求，非常好。然而，该产品型号患有等缺点舒适和卫生水平低，产品必须安装在屋顶上的整体，这不仅影响建筑物外观，但也带来了一个问题，与建筑的融合。目前，真空集热管热虹吸系统是在中小城市和农村地区流行，但它不能满足高端客户的需求，为生活在城市地区和高品质的热水。这也解释了为什么在北京和上海这样的大城市，太阳能热水器的市场是比较小的。此外，这一个事实，即中国的太阳能热水器市场的产品是在产品类别和同质化严重，不能满足用户的各种需要，尤其是高端客户的需求作出了贡献。在过去的几年中，分隔的，间接的，加压的产品的研究，开发和生产已成为主要的太阳能热水器企业的优先级和输出这些产品逐年增加。
7 结论
为太阳能热水器行业的发展提供了基础，如果要发展一个产业，其产品，以满足用户的需求，赢得市场的认可度。当时在中国的常规能源供应系统不完善太阳能热水器的发展提供了一个机会，而太阳能热水器产品从一开始的生活热水符合中国居民的需求。同时，太阳能热水器产业化，加快了降低成本，并极大地推进了性价比，使产品赢得了市场的广泛认可和满足市场需求。因此，产品满足市场的需求的太阳能热水器行业的快速发展提供了基础。
中国的主流产品是结构简单，成本低。这是非常好的热式电热水器的经济刚刚开始发展，以满足人们的需求。其他许多发展中国家都和中国的情况非常相似。
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Solar energy water heater intelligent control system design
Hu Runqing
Journal of Beijing university
Bei Jing 855000
Abstract: in today's increasingly tense energy, electric water heater, water dispenser, rice cooker and the like household electrical appliances in the heat preservation, due to its simple temperature control system, two-line hybrids resistance to achieve temperature control, thus could do a lot of energy waste.But using AT89C52 single chip microcomputer as the core, with temperature sensor, signal processing circuit, display circuit, the output control circuit, the control system composed of fault alarm circuit and so on can solve this problem.Single-chip temperature sensor can be detected by analog conversion to digital quantity, water temperature and displayed on the LED digital tube.The system has strong flexibility, easy operation, high reliability, etc.There more broad prospects for developmt.
Keywords:policy/A/D conversion/DS18B20
1 Rapid development of solar water heater in China
1.1 Stages of development
The 1970s saw the beginning of solar thermal application in China. In late 1980s, with the introduction of Canadian produc-tion line of copperaluminum composite absorber for flat platecollector and the development of production line of self-designedanodic oxidation selective coating, China began to manufactureflat plate solar water heater. But the progress was slow due to theproblems like cost and compatibility in winter. Major break-throughs made in the 1990s in the technology and production of all-glass vacuum tubes enabled China to develop self-designed production line of vacuum tubes and start mass production of solar water heater with all-glass vacuum tube. All these achievements in science and research putting into production have contributed to the constant improvement of the productivity of solar collector and water heater with all-glass vacuum tube and heat-pipe and the reduction of cost. It gives great momentum to the industrialization of China’s solar thermal industry.With the development of economy, the demand of urban and rural residents in China for living and bathing has increased substantially. Together with electric water heater and gas water heater, solar water heater becomes one of the major products supplying hot water for domestic use.
figure 1
1.2 Stable and rapid growth of the market
Since the 1990s, the market of solar water heater in China has maintained a rapid growth in over ten years. The annual output of solar water heater increased from 6.1 million square meters in the year 2000 to 42 million square meters in 2009, with an annual growth rate of 24%. The accumulated installation of solar water heater increased from 26 million square meters in 2000 to 145 million square meters in 2009 with an annual growth rate of 21% Zhentao and Zhichen (2010). Especially since the Renewable Energy Law took effect, the application and extension of solar water heater has been greatly advanced thanks to the enforcement of national policies concerning the development of renewable energy, the construction of the new countryside and the local governments mandatory installation policy for solar water heater in new buildings. From 2006 to 2009, the average annual growth rate of the sales of solar water heater stood at 33% and the total inventory grow 17% annually on average, which marked that the application of solar water heater had reached new heights. Chart 1 represents the annual output of China’s solar water heater from 1998 to 2009 and its growth rate and Chart 1 represents the inventory of China’s solar water heater from 1998 to 2009 and its growth rate.
2 The temperature detection circuit design
Temperature detection part is the important link to realize intelligent temperature control, only accurately detect the temperature, can through the software to realize auxiliary heating. The stand or fall of its performance directly affects the performance of the system, the temperature detection, this design USES the temperature sensor
DSl8B20 digital thermometer with nine (binary) temperature readings, the temperature of the indicating device information through a single interface into DSl8B20 or from DSl8B20. Therefore only a line from the host CPU to DSl8B20 (and earth). DSl820 power can be provided by the cable itself without the need for external power supplies. Because every DSl8B20 has given the unique serial number in the factory, so any multiple DSl8B20 can be stored in the same single wire bus. This allows the temperature sensitive device is placed in many different places. DSl820 measurement range from 55 ℃ to + 125 ℃ increment value is 0.5, is available in ls (typical) the temperature transform into digital.
3 Analog/digital conversion circuit
A/D conversion is the sensor input analog conversion to digital quantity into single chip microcomputer. This design USES is ADC0832. Generally ADC0832 with single chip microcomputer interface should be four wires, CS, CLK, DO, DI. But as a result of the DO end with DI end when the communication is not effective and at the same time with single chip microcomputer interface is a two-way street, when circuit design so DO and DI may be connected in parallel on a cable to use. When ADC0832 did not work the CS input end shall be the high level, the chip disabled, CLK and DO/DI level can be arbitrary. When must carry on the A/D conversion, must first put CS side at low level and low level until the end of the transform. Chip began to work, at the same time provided by the processor to the chip clock input CLK clock pulse, the DO/DI end is using DI end data signal of input channel function selection. Ahead of the first clock pulse DI side must be a high level, said to start.
4 LED display circuit
In a single chip microcomputer system, commonly used display have leds show, fluorescent tube, digital tube display and liquid crystal display (LCD). In recent years, are also beginning to use simple CRT interface, showing some of the Chinese characters and graphics. Light emitting diode display is divided into fixed period and, according to a large field can be assembled and classification of common cathode and anode.
LED display block is made up of countless luminous digital tube display, digital tube every digital section is a light emitting diode, when light emitting diode conduction, corresponding to a point or a stroke, control combination of light-emitting diodes (leds, can show the required character, there are seven sections and fields. The display block has a total of two kinds of common cathode and anode. Common cathode LED display light-emitting diode cathode connected together, the public usually grounded cathode, anode for high electricity at ordinary times when a light-emitting diodes (oleds), leds light up, and the corresponding period is displayed. Similarly, a total of anode LED display light-emitting diode piece of anode together, usually the public positive voltage anode. When a light emitting diode cathode low electricity at ordinary times, leds light up, and the corresponding period is displayed. LED display has a static method and dynamic display mode.
5 working principle of the system
Using DS18B20 sensor of water tank temperature real-time monitoring, when the water temperature signal is detected, feedback to the microcontroller, and digital tube dynamic scanning mode shows the current temperature and the preset temperature. Way of electrode measured water level, when the electrode of water before each class, using water weak electrical conductivity, the voltage at about 3 v, after schmidt triggers into 0 v, with the voltage difference on both ends of the water level indicator lights; On the contrary, no contact with water at 0 v voltage, after schmidt triggers into 5 v, no voltage difference on both ends of the water level indicator, namely no current through, light is out. When there is a lack of state (when water level is lower than 20%), buzzer alarm, all the water level indicator light go out. Isolating circuit is used to to automatic heating and water system, specific conditions by a software program to control, so as to realize intelligent.
6. Experiences and features of solar water heater in China
6.1 Commercialized operation has been realized with policies
Neither the market nor the manufacturers enjoy incentive fiscal and taxation policies for solar water heater in China. Compared with electric water heater and gas water heater, there is no preference for solar water heater. Only solar water heater companies classified as high-tech enterprises by local governments can enjoy preferential policies for high-tech enterprises. The demand of the market is the driving force behind the development of solar water heater market in China, so it is the demand of the residents for hot water in small and medium sized cities and rural area that has promoted the development of the market, but not the incentive policies of the country. Solar water heater meets the residents bathing needs with high performance-
price ratio. This is the motive power for its rapid development. Solar water heater becomes one of the major products supplying domestic hot water for people together with electric and gas water heater, and gradually becomes leading product because of
its high performance-price ratio. The initial investment of solar water heater is higher than that of electric water heater and gas H. Runqing et al. / Energy Policy 51 (2012) 46–51 49water heater, but the solar water heater does not consume fuel and its annual operation cost is low, so the average cost in its life cycle is only 1/3 of the other two types of water heater. Thanks to the sound performance-price ratio, the market share of solar water heater in China has increased constantly from 15.2% in 2000 to 57.2% in 2009 Zhentao and Zhichen (2010), indicating that solar water heater has become the mainstream product on the Chinese market. Chart 3 compares the economical efficiency of solar water heater with the other two types of water heater.
6.2 Vacuum tube-a thermal siphon system
The mainstream product in China is vacuum tube thermosiphon system compared with advanced indirect and pressurized product in the world, this type enjoys advantages like simple structure, low technical requirements and low production cost.
Also, through years of efforts, the production and market of this model has reached certain scale, the quality of the product is guaranteed with high economical efficiency and the product meets the demand of the current Chinese market very well.However, this product model suffers from disadvantages like low comfort and hygiene level, and the product must be installed on the roof integrally which not only influences the appearance of the building but also poses a problem for integration with the building. At present, the vacuum tube thermosiphon system is popular in small and medium sized cities and rural area, but it cannot meet the demand of high-end customers in urban areas for life and hot water of high quality. This also explains why the market of solar water heater in big cities like Beijing and Shanghai is relatively small. Also, this has contributed to the fact that products on China’s solar water heater market are small in product category and severely homogenized, which cannot cater to various needs of users, especially the needs of high-end customers. In the past few years, the research, development and production of separated, indirect and pressurized products has become the priority of major solar water heater enterprises and the output of theseproducts increases year by year.
7 Conclusion
Provides a foundation for the development of the solar water heater industry, if we want to grow an industry, its products, to meet the needs of users, win the market recognition. When conventional energy supply system is not perfect in China solar water heater provides an opportunity of development, and the solar water heater products from the beginning of living hot water can meet the demand of China's residents. At the same time, the industrialization of solar water heater, speeds up the cost reduction, and greatly promote the performance-to-price ratio, make the product won the broad market recognition and meet the demand of market. Products to meet the demand of the market, therefore, the rapid development of the solar water heater industry provides the basis.
China's mainstream products are simple structure, low cost. This is a very good water heater is just beginning to economic development, in order to satisfy people's needs. Many other developing countries and China are very similar.
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