Simulation And Experiment Research Of Direct-Expansion Solar Assisted Heat Pump Experimental System

Direct-expansion solar assisted heat pump multi-function machine (DX-SAHPM) is to combine organically solar heat utilization technology with the conventional air source heat pump, which is a new type of green equipment with environmental protection and energy-saving. It centralizes the refrigeration, heating and supplying domestic hot water to a system, and furthest display the energy conservation superiority of solar and heat pump. As a new method that the renewable energy effectively uses in the construction energy conservation aspect, it also promotes the steady advancement of the sustainable development strategy.In November, 2005, the project group designed a set of mini-type experimental prototype of DX-SAHPM and developed a set of supervisory system based on PLC+ screen touching technology, which is used to test thermal performance parameter under possible conditions of operating mode, in order to carry on performance analysis and further optimize the design.In this dissertation, on the basis of the three law of conservation of mass, conservation of momentum and conservation of energy, the major components' the mathematical models of DX-SAHPM experimental system have been established. After the simulation for major parts, the steady state simulation of system was accomplished by coupling of the simulation of components. The state parameters and COP under different work condition can be calculated by the steady state simulation program with Visual Basic language, and the analysis and forecasting in theory can be carried on.The computer monitor and control system based on the PLC + touched screen which have been designed and developed specially for the experimental system can realize the real time monitor and memorize the data automatically. Every performance index for system running can be draw after the process of the experimental data , and the running characteristic of the system can be understand directly. The experimental test to DX-SAHPM experimental system lasted two months during the spring and winter under the heating model. Some conclusions can be draw. Both the COP and heating load have a large scale enhancement for adding solar collector and the system can simultaneously absorb solar radiation energy and air heat. The experimental system shows good operating characteristic under various operating mode, and achieve estimated effect of the experiment.The model for exergy analysis of experimental system has been established. According to the experimental data in spring, the exergy loss was calculated under heating mode. The results show that the exergy losses of compressor and solar collectors account for 45.8% and 21.4% respectively in the whole losses. The reasons were analyzed, and the results indicate the energy-saving potential and provide the credible basis for optimizing system further.On the basis of the integrated analysis to the first and the Second law of thermodynamics, the two evident problems were pointed out: 1.The area of solar collector can't match the capacity of compressor; 2.the conventional throttle-capillary can't satisfy the need of fluid regulating. The related solutions were also analyzed and discussed and the further study direction was indicated.The theory and experiment analysis of DX-SAHPM experimental system operation characteristic provide the necessary theory and technology supply for the popularization of direct-expansion solar assisted heat pump technology and accelerate the industrialization course.