Abstract: The investigations on the semisphere cavity receiver of dish solar system are focused on its convection heat loss, the input of the model is unrealistic and the realization process is too complex, there is no outdoor experiment about this. So the optical analysis is obtained by TRACEPRO, a new model is presented combined with heat transfer theory, The accuracy of the model with high operating rate can meet the requirements of engineering. Outdoor experiments with dish solar collector are done to prove the new model. The heat transfer fluid is oil. Finally the investigations on some factors which have influence on the efficiency are done by the model, the conclusion are follows: the flow rate should be keeped higher than the minimum to avoid the laminar flow when decrease inlet temperature, it is similar when decrease the flow rate. The efficiency will decrease when the radiation intensity is too high, so the concentration ratio of solar thermal system should not be too high. The influence on efficiency is very small when flow rate is high, and exergy of the oil decrease with the increase of flow rate, the efficiency and outlet temperature both increase with the decrease of flow rate when radiation is low and temperature is high.

Key words: semisphere cavity receiver;dish solar system;solar energy;efficiency