The Greenhouse Air Source Heat Pump Heating System Research

Greenhouse is the important symbol of modern agriculture. In order to ensure the normal growth of the greenhouse crops in the whole year, the staff must heat the greenhouse in colder seasons. On the basis of analyzing and summing up the greenhouse heating situation at home and abroad, this article design and build a greenhouse air-source heat pump heating system, and developed a greenhouse heating monitoring device based on single chip microcomputer. At last, it makes experimental study on the performance of greenhouse systems and the heating effect of the system.Firstly, this article makes a detailed analysis of the theory of greenhouse heating, including the design and calculation of heating load in greenhouse. It also makes the analysis and comparison of greenhouse warming and heating equipment. Based on this, it makes studies on greenhouse heating equipment and system layout.Heat pump is highly efficient energy-saving heating equipment and no pollution to the environment during the heating process. On the basis of a detailed analysis of work principle, composition and structure to the heat pump system, author makes a design that combined with the theory of greenhouse heating for greenhouse air source heat pump heating system. It completed the structure of system, and made a detailed description for the various parts of the system and parameters.Secondly, for the system to achieve the functions, author use STC89C52 microcontroller as the core to design hardware and software of the control device, including that user can optionally set greenhouse temperature values through the keyboard and use temperature sensors to make multipoint collection of temperature inside the greenhouse. It can be displayed by LCD and makes the realization of temperature automatic control of equipment and so on. Then, author use VB language to design a human machine interface for greenhouse heating system. By this interface, staff can do real-time monitor to parameters of greenhouse temperature, environment temperature and water temperature. It also completes records of test data.Finally, the author make study on greenhouse heating system that was built, including the air-source heat pump efficiency, the ability of keeping warm of the water tank, and the effect of greenhouse warming. By the study we found that under the climatic conditions in Kunming, the average COP of air-source heat pump is 3.32 during the test; in the absence of solar radiation case, average temperature drop rate of tanks is 0.29℃/h within 12 hours; whether in cloudy or sunny days, greenhouse temperature can above the set temperature 15℃, air-source heat pump heating system can meet heating requirements of greenhouse.At the end of this article, author summarizes the contents of the study and makes a prospect of research. Heat pumps, as greenhouse heating equipment, have the advantages of energy-saving and environmental protection. It can be applied to agricultural greenhouse warming system and has broad application prospects.