英文翻译毕业论文太阳能热水器

欢迎下载本文档参考使用，如果有疑问或者需要CAD图纸的请联系q1484406321The performances of the simulation ofthe solar water heater control systemAbstractThe present paper deals with a simulation based on the ISIS-PROTEUS software to design a solar heater of water control system by using the PIC 16F877 microcontroller based on the PROTON programming language. The reserves of oil in different countries were been illustrated. A short demonstration of the worldwide potentiality in solar water heater has been focused with the actual needs of alternative economical strategies to heat the water. A general principle of the solar water heater and its parts was presented to describe the real plant. The simulation was been realized by using ISIS-PROTEUS software and the results have been carried out using a digital LCD which displays the hot water temperature. This temperature varies between the minimal value 20oC and its maximal value 70oC. The results prove the competitiveness of the solar technology with the performances of the simulation of the solar water heater control system which can be tested soon in real time by developing the analyzed study as an electronic circuit connected to a solar water heater.Keywords：Control systems; Solar energy; Water heater; PIC 16F877; Renewable energy.I.INTRODUCTIONThe global demand for energy and more specifically clean energy is growing rapidly. There is a universal need for efficient technologies that will contribute to the sustainable development of the host countries and communities by providing employment, improving quality of life and protecting the environment 2. The renewable energies are clean, are used where they are and their decentralized character is well appropriate at the scattered state of the areas with low density of population. They can contribute to the environment protection and be regarded as a future alternative to conventional energies, particularly in the rural world which constitutes a potential market because of the prohibitive cost of the routing by cable of electricity 11.The renewable sources of energy are converted into useful energy while: Contributing to the reduction of the greenhouse gas emissions; Providing opportunities for poverty eradication; Limiting the risks and the pollution of the planet; The primary energies are distributed non-uniformly over the globe. Some countries depend on other nations for their energy supply. This implies economic and trade can play a major role in relations between states. These reserves are located, for the most part, outside areas of high consumption. This dependence of industrialized countries against exporters may generate serious crises that could threaten the fragile balance socio-economic world (oil shocks of the 70s, the Gulf Wars, .). Table (1) shows the statistics of oil reserves in 2000 9. As the demand for fossil fuel grows while reserves start to taper off, the idea of alternative energy sources are offered up. Alternative sources of energy can become a satisfactory substitute for fossil fuels. The most satisfactory single alternative would be solar energy. One may discover that wind, solar, biomass, etc., all piled on top of each other, may have to do, but their success may turn out to require an effort that started a generation ago.The most popularly suggested alternative energy is solar; his last suffers because it is intermittent sources of energy, and the end product is electricity. There is no way to store large amounts of electricity for use when wind and sunshine are not with us. Geothermal and tidal energy are insignificant energy sources in total but can be locally important.II.SOLAR ENERGYThe sun is a giant ball of hydrogen and helium gas. The enormous heat and pressure in the interior of the sun cause the nuclei of two hydrogen atoms to fuse, producing one helium atom in a process called fusion. During fusion, nuclear energy is converted into thermal (heat) and radiant energy. The adiant energy is emitted form the sun in all directions and some of its reaches Earth. Radiant energy is energy that travels in electromagnetic waves and rays. Radiant energy includes visible light, x rays, infrared rays, microwaves, gamma rays and others. These rays have different amounts of energy depending upon their wavelength. The shorter the wavelength, the more energy they contain 3.Only a small part of solar energy that the sun radiates into space ever reaches the earth, but that is more than enough to supply all our energy needs. Every day enough solar energy reaches the earth to supply our nations energy needs for a year.It takes the sun energy just a little over eight minutes to travel the 93 miles to the earth. Solar energy travels at a speed of 186,000 miles per second, the speed of light. Today people use solar energy to heat buildings and water and to generate electricity 7.III.SOLAR WATER HEATER IN POPULAR WORLWIDESolar hot water systems capture energy from the sun to heat water for homes and businesses, thereby displacing the use of natural gas, or in some cases electricity, with free and limitless solar energy. Solar hot water could save some billion thermos of natural gas a year. To prevent global warming pollution, reduce dependence on imported fuel, and ease the price of natural gas 5. An example of solar water heater is shown in figure (1).Those systems uses energy from the sun to heat water, reducing the amount of natural gas, or in some cases electricity, needed for residential or commercial water heating. Solar hot water systems are highly efficient; up to 87 percent of the suns energy that reaches a given section of roof can be absorbed by the systems collector. Liquid in the collector, heated by the sun, is pumped to one or more storage tanks, thereby reducing or eliminating the need for conventional water heater fuel. The benefits of using the solar water heater are the followings: Heating water with sunshine costs less. Once it is bought, the water heating costs will be zero; A solar water heater cannot give a shock or set fire to the house like electrical or flame based water heating systems; Solar water heaters do not make any smoke, so they dont make the home smell or get dirty; If one usually heats water with gas or electricity from fossil fuels, a solar water heater helps; reduce the carbon dioxide produced by the household, helping in the fight against global.Solar hot water heaters have been in use in various parts of the world since their inception. While conceptually simple, the systems continue to improve as newer technologies enhance performance. As environmental, political, and financial concerns with fossil fuels grow worldwide, solar hot water has become popular in many countries 10.Mediterranean climates are characterized by warm summers and mild winters, making them ideal for solar hot water systems. The small temperature range throughout the year allows the systems to cover most hot water demands in the winter without overheating in the summer, meaning a larger portion of the water heating needs can be provided by the sun. Figure (2) demonstrates the total world solar hot water capacity by country from which we can conclude that China used the maximum possible number of solar water heaters, In European Union, solar water heater can save 13% from its resources and emissions, Turkey has 6% from the world exploitation in solar water heater, and the other countries disturb about 20% world capacity 5. IV.CONTROL OF SOLAR WATER HEATERS PRINCIPLEIts about solar water heaters, which use the suns energy to heat water for the home or for use in business. This is becoming more popular in many African countries, especially for people who have water piped to their homes. Larger systems are now being used in hospitals, schools and hotels. The costs of installing solar water heaters vary, but once for the system have been paid; it is a very cheap way to have hot water because sunshine is FREE! 8.A solar water heater is any system that uses the thermal energy of the sun to heat water. They are usually aimed at heating water to a temperature hot enough for washing clothes, washing dishes, and personal hygiene, but not hot enough to cook with straight away. However, as long as it is clean, the hot water can also be used in cooking to save time and fuel 1. This project relates to a control and protection system for a solar water heater apparatus, which incorporates a temperature controlled variable speed drive for the circulating pump, and a drain down valve which is responsive to low collector temperature, high tank temperature and also to power loss, to serve in combination as a device to optimize efficient energy collection. The solar water heater with a control system as shown in figure (3) is suitable for all different configurations. It is usually consists of three parts as follows:A.Solar collectors A flat solar collector is a very simple machine. It consists of an insulated rectangular box. It contains a metal plate (usually copper) that has been painted black, with a pipe at each end (called headers) that are connected to small tubes (called risers) also made from pipe. Water flows from the header into the risers. Water is first heated in the risers and then returns to the storage tank. The entire box is covered with a special glass that is hail resistant. The entire box is then installed, usually on the roof of a building, and tilted so it can capture as much sunlight as possible 2.B.Storage tanks Whether one uses a direct or indirect solar water heater, a large storage tank will be needed. The most commonly used size is 80 gallons. Solar water storage tanks look similar to standard water heater tanks. But they are very well insulated to save the heat gained by the collectors. Water is usually transferred from the solar water storage tank to a standard water heater tank. Solar water heaters can heat water to a temperature that is much higher than needed in the home. Therefore, special valves, called tempering or mixing valves, are recommended to control the water temperature. If the solar heated water is too hot, it mixes cold water with the hot water before it reaches the faucetC.Group of transfer and control It contains the water channels to carry the cold water from the tank cold storage to the collector, and the hot water from the collector to the tank heat storage. These channels can be metallic or isolating 4. V.PROTON PROGRAMFigure (4) shows the program of this project written in PROTON programming language which is the one of the most popular language for microcontrollers programming, the program and after its execution, it must be converted to Hexadecimal to be introduced to the PIC 16F877 automatically, it can be also written in other programming languages and introduced to the microcontroller by other methods. VI.ISIS SIMULATIONThis simulation is built in ISIS-PROTEUS efficient software for electronics engineers. The thermal sensor in this simulation can be represented by a voltage divider which sends an electrical signal to the analog port RA0/AN0 of the PIC. The ports RB0-RB6 and RD5-RD7 are the outputs which can be connected to four digital LDC, to display the temperature of the hot water. The output RD0 feeds in the DC motor. This last adjusts the valve that passes the hot water 6.The need to simulate the constructed program appears indispensable from which the use of ISIS software; help to well visualize the good operation of the system. One has to verify the operation of the program before transferring it to the microcontroller, which helps to economize the time and to increase the life duration of the PIC, for this we have used the Hexadecimal file of the program. Figure (5) shows the simulation of this project by using the ISIS-PROTEUS.VII.SIMULATION RESULTSOne changes the NTC (negative temperature coefficient thermistor) value between two specified values T-MIN=20oC, and T-MAX=70oC. Certain values of the measured temperature of the water are displayed in the LCD screen as shown in the figure (6), from which one can remark that the DC motor, which symbolizes the pump in real time, doesnt operate ever if the temperature exceeds T-MAX70oC, and then if one minimizes this temperature, the DC motor doesnt stop ever when the temperature is lower or equal to T-MIN20oC. Table (2) presents the results of the simulation of solar water heater system taken by selecting different cases of the NTC. The minimum temperature is T-MIN=20oC, and the maximum temperature is still set to a value of T-MAX70oC. We try to increase and then to decrease the temperature of the NTC, and note the state of the pump and then the movement of water depending on water temperature at the inside of the radiator 9.VIII.PIC 16F877APIC microcontroller signal pins B. Commonly used memoryPIC16F877 microcontroller memory architecture:l4-bit*8K FLASH program memory512*8-bit data memory RAM256*8-bit power-off protection data EEPROM memoryData register, Memory is a very important component of the microcontroller, specifically for the storage of instructions, data and computational results. Memory come from the use of function points, random access memory RAM (Random Access Memory) and read-only memory ROM (Read Only Memory) can be divided into two categories.Program memory, PIC16F87X microcontroller internal configuration of 8K * l4-bit Flash program memory (FLASH), you can easily erase online and programming, and life up to 1000 times or more.The PIC16F87X program memory 13-bit program counter (PC). PC pointer 13 of the program addresses the maximum addressable memory space is 8K, the corresponding address code range 0000H lFFFH.Select register (OPTION-REG) is a read / write 8-bit registers its function is for configuration TMR0/WDT prescaler, the external INT interrupt, TMR0, and Port B weak pull-up.CONCLUSIONThe world reserves will be decreased, which requires and encourages the use of solar energy and its exploitation as primary source. Solar water heater is an important device, which requires an efficient strategy to be well drove and controlled. The obtained results prove that the water can be heated and its temperature can attains the desired temperature degree depending on the two specified values limits of temperature. The actual simulation can be developed in real time to validate the constructed simulation with the corresponding program.REFERENCES1 M. Merzouk and N. K. Merzouk,Le Chauffe-eau Solaire Usage Domestique Analyse des Limites Technico-Economiques delExprience Algrienne, Revue des Energies Renouvel