Study Of The Energy Saving Optimization Control Strategy For Parallel Heat Pump–assisted Solar Hot Water System

With the improvement of people's living standard, the demand for hot water is increasing, As well as the quality of the hot water becoming higher and higher. the energy consumption of living hot water is an important part of building energy consumption, the traditional ways have a large consumption of fossil energy and make serious pollution to the environment, which cannot adapt to the Social theme of save energy and protect the environment. Therefore, it is urgent and important to find a new way of high efficiency for hot water supply. Solar energy has been widely used because of its renewable, clean, pollution-free and so on. However, due to its own shortcomings, it is still restricted in the application of large hot water projects. Firstly, the solar energy resources is Unstable, when the weather is fine, the amount of solar radiation is sufficient enough to hot water supply; when encountered rainy weather or night, it is not enough to hot water supply. Secondly, It take a long time to heating the water and the water temperature go up slowly, which are not suitable for the conditions need stable water supply. Therefore, the heat pump technology is gradually being concerned by people. The heat pump technology is a kind of energy saving system which can provide heating and cooling service for winter and summer. It is a device which use a small amount of high taste energy to transfer heat from the low temperature heat source to the high temperature heat source. Heat pump unit can meet the needs of the whole day hot water production, but if used alone, it ignores the effective use of solar energy, When combined with Solar energy, it can effectively use solar energy, with the heat pump as an auxiliary device of solar energy, it can also achieve stable water supply.parallel heat pump- assisted solar hot water system is developed on the basis of solar energy and heat pump technology, parallel heat pump- assisted solar hot water system is widely used in large-scale water projects with the advantages of energy-saving, environmental protection and reliable, At present, the control technology of the parallel system is mainly simple logic control and ensure water after fixed time, which does not apply to occasions that require stable water supply all the day. At the same time, some control strategies are on the base of human experience, which lack of theoretical support; and a part of the research focuses on establish the prediction model of solar energy and heat pump unit, which cannot adjustment control strategy according to the current water consumption.In summary, the significance of the research is put forward a new control strategy, which can make a stable water supply adapt to the current water consumption, At the same time, it can make an effective use of solar energy, reduce the turn-on time of heat pump and save energy effectively, to achieve this goal, the main tasks of this paper are:(1) According to the fundamental principles of heat pump –assisted solar hot water system and analyze the different operation modes in different weather conditions, In order to achieve the goal of provide stable water supply and use solar energy efficiently,the paper propose a new control strategy which can control the solar pump by temperature difference, and control the heat pump unit by heat difference.(2) Have a study on the temperature distribution of hot water tank, establish the model of the heating water tank, setting the boundary conditions by testing, Then, simulate the temperature change and proposed methods of optimizing the existing water tank, Which contribute to improve the efficiency of the system.(3) According to the requirements of the optimal control strategy, design and make the controller for parallel heat pump- assisted solar hot water system, which can realize multi parameter detection and multi object cooperative control by using the Single chip microcomputer control system. The optimal control strategy is fully realized.(4) Build the experiment platform of parallel heat pump–assisted solar hot water system and apply the control strategy to the experiment. when it is rainy day and the temperature is low, the outlet temperature of the solar collector is about eleven degrees, the heat pump start. when it is sunny day, the outlet temperature of the solar collector is about Seventy-one degrees, When the water temperature is getting lower,the solar unit starts firstly, the water temperature is always maintained at more than 55 degrees. The results show that the control strategy which control the solar pump by temperature difference and control the heat pump unit by heat difference and water consumption can make effective use of solar energy, as well as provide the stable water supply all the day. The intelligent controller has the advantages of simple, reliable and can be widely used in the actual parallel heat pump- assisted solar hot water system, which can not only meet the needs of dynamic water supply, but also reduce the energy consumption of the system.