A Study On Collector And System Of Organic Rankine Cycye Driven By Solar Thermal Energy

The overall trend in the world of energy requires people to use more green renewable energy, such solar energy as an important renewable energy has broad prospects. Solar Organic Rankine Cycle (ORC) system which can take advantage of the low-medium solar thermal energy has a unique superiority. Current research on solar ORC is mainly about ORC performance, with little attention paid to solar collectors for ORC system.This thesis chooses trough solar collectors for heat collection of solar ORC system according to the characteristics of ORC. Optical and thermal properties of trough solar collectors are researched. And combined with ORC, trough solar ORC system is researched. The main research content and the corresponding results could be concluded into five aspects as follows.1. A computational model of direct normal irradiance (DNI) and trough solar collector optical efficiency are established. DNI and trough solar collector optical efficiency are calculated through the VB programming language based on the models. A thermal performance model of trough solar collectors is established.2. A set of 1 OOkW trough solar collectors is calculated and designed.3. A solar concentrating model of trough solar collectors is established. Research on the concentrating characteristics and surface heat flux of trough solar collectors is made through the SOLTRACE software.4. Considering the non-uniform surface heat flux of the trough receiver, a mathematical model of trough solar collectors is established. The performance of trough solar collectors is simulated using the FLUENT software. The simulations indicate that collector efficiency improves with the increase of DNI, air temperature and fluid inlet velocity, degrades with the increase of wind speed and fluid inlet temperature. Heat-transfer fluid temperature rise increases with the increase of DNI and decreases with the increase of fluid inlet velocity. Pressure loss increases with the increase of fluid inlet velocity, decreases with the increase of DNI, inlet temperature. The maximum temperature difference of absorber tube rises with the increase of DNI, reduces with the increase of fluid inlet velocity. And with the increase of fluid inlet temperature, the maximum temperature difference reduces firstly and then rises. The maximum temperature difference of glass cover rises with the increase of DNI and inlet temperature, reduces with the increase of wind speed, air temperature and inlet velocity.As temperature difference of absorber tube is too big under low fluid inlet velocity, three kinds of trough solar collector’s structure optimization method are proposed.5. A parabolic trough ORC solar thermal power generation system is designed. And the mathematical model of ORC is established. Research of the solar ORC system is carried out with the model. The results show that overall efficiency and expander output power improve with the increase of DNI and fluid inlet temperature, degrade with the increase of fluid inlet velocity. When the temperature of receiver’s inlet and outlet is fixed, there is an optimum inlet velocity which is concerned with inlet temperature and DNI. When the system’s operating conditions are changed from DNI=450W/m2, Tin=100℃ to DNI=900W/m2, Tin=150℃, the optimum inlet velocity changes from 1m/s to 1.2～1.4m/s.