In order to utilize solar energy effectively and to achieve a higher electrical efficiency by limiting the operating temperature of the photovoltaic(PV) panel,a novel photovoltaic/thermal solar-assisted heat pump(PV/T-SAHP) system was proposed and constructed. The hybrid solar system generates electricity and thermal energy simultaneously. A distributed pa-rameters model of the PV/T-SAHP system was developed and applied to analyze the system dynamic performance in terms of PV action,photothermal action and Rankine cycle processes. The simulation results indicated that the coefficient of performance(COP) of the proposed PV/T-SAHP can be much better than that of the conventional heat pump. Both PV-efficiency and photo-thermic efficiency have been improved considerably. The results also showed that the performance of this PV/T-SAHP system was strongly influenced by the evaporator area,tube pitch and tilt angle of the PV/T evaporator,which are the key factors in PV/T-SAHP system optimization and PV/T evaporator design.
Gang PEI Jie JI Ke-liang LIU Han-feng HE Ai-guo JIANG
A micro turbo-expander capable of high working speed was specially manufactured for use in an organic Rankine cycle (ORC).A series of tests were executed to examine the performance of the machine.In the experiment,the machine was tested under different inlet pressure conditions (0.2-0.5 MPa).Data such as the compressed air pressure,temperatures of the inlet and the outlet,rotational speed,and electric power generation were analyzed to discover underlying relationships.During the test,the rotational speed of the machine reached as high as 54 000 r/min,the peak value of the temperature drop between the inlet and the outlet reached 42 ℃,the maximum electric power generated by the motor-generator attached to the machine reached 630 W,and the efficiency of the machine reached 0.43.
