Study Of The Opening Of The Electronic Expansion Valve To The Photovoltaic-Solar Assisted Heat Pump System

With the rising of population and energy consuming on earth, the fossil energy on earth is stepping into exhaustion and the issues of environment are facing grimness . The utilization and development of solar energy are improving greatly. The Photovoltaic Solar Assisted Heat Pump (PV/T-SAHP) system which integrated heat pump and solar energy collector can heighten the COP (coefficient of performance) and the utility efficiency of solar energy simutaneous is a main way of utilization of solar energy.Based on the photovoltaic and the technology of variable frequency and the DXSAHP (direct expansion solar assisted heat pump),we proposed the idea of the PV/T-VFSAHP (Photovoltaic-Variable Quency Solar Assisted Heat Pump) .Combined the mathematical mode of the PV/T-SAHP system , system performance and optimization under the affecting factor of solar radiation, condensing water temperature, surrounding temperature , and the superheat of evaporator were studied. Based on the results ,the optimal control strategy of the system was put forward.viz.the control of the EXV-the superheat degree of the collector.By this way, the system can maintain more COP and more the efficient of the collector at no matter what status of the system,such as the standard status , the variable status, the full load and the variable load.When the variable frequency compressor run at a constant frequency ,its performance worthiness a fix velocity compressor move with a sameness frequency.So the PV/T-VFSAHP can disperse to a lot of fixed velocity compressor corresponding different frequency. Therefor the key of the study of the PV/T-VFSAHP is to probe the effecting of the opening of the EXV to the system.Basing on the test rig and mathematical mode of the PV/T-SAHP system ,we developed the controller of the openning the EXV (Electronic Expansion Valve).At the same frequency of compressor, under different opening of EXV, outdoor tests were conducted on the PV/T-SAHP system. The dynamic behavior of PV/T-SAHP was analyzed . The COP of the system reduced along with the raising of temperature of the condensing water .The peak value of the efficiency of the photovoltaic is occurred while the balance between the cooling influence of the vaporizing working material to the PV/T module and the heating influence of the air to the collector/evaporator, not the vertex of the solar radiation. The vibration of the power of the compressor appeared when the raising of the solar radiation at a fixing opening of EXV. when at the maximum opening of the EXV, the vibration is especially evident. The vibration is harmful to the economical and security of the system .Increasing and decreasing the superheat degree of the evaporator ex parte are all mistake.The only way to utilize the availity area of the evaporator and to gain the maximum economocal of PV/T-SAHP is to find the MSS of the system.So we brings forward the principal of the stability of the PV/T-SAHP system .At the same time point out the key of the study of the PV/T/T-SAHP is to discover the relation of the solar radiation and the superheat degree of collector/evaporator.At last , we simulation and analyzing the performance of the PV/T-SAHP system based on the mathetical mode of the PV/T-SAHP system under different frequency of compressor ,and carry through the experiment when the frequency is 30hz,50hz,70hz...