Numerical Simulation On Cavity Type Of Trough Solar Collector

The solar energy is an abundant resource which is without transportation costs ofthe renewable energy. The current major international utilization of solar energy technologies are the solar photo-voltaic utilization, the solar photo-voltaic utilization, the solar photo-thermal utilization and the solar photo-chemical utilization. The solar condensing technologies include the trough solar condensing technology, the tower solar condensing technology and the dish solar condensing technology. The utilization of light and heat of trough solar is a kind of technology which has been put into the commercial operation at present.According to the numerical simulation for the optical properties of the cavity type of trough solar collector by the software of TracePro, the following conclusions can be got: With the increase of the directing solar irradiance, the total luminous flux increases and the optical efficiency remains unchanged. With the increase of the reflectivity of the paraboloid and the absorptivity of the receiver, the total luminous flux and optical efficiency both increase. The optical efficiency and the total flux of the distance from the paraboloid to the receiver change by approximately normal distribution. With the increase of the area of the cavity shadow area, the total luminous flux decreases and the optical efficiency increases. With the increase of the opening width, the total luminous flux increases and the optical efficiency decreases. The optical efficiency for different cavity shapes descending highest five tube layouts were: vertical display, along the top row display, insert the top row display, placed at the top of dispersion and focus placed on the top. Take the y-z axis as the center plane, with the incident angle along the z axis increasing both to the left and to the right, the total luminous flux decreases and the optical efficiency decreases until holding steady. Take the x-y axis as the center plane, with the incident angle along the x axis increasing both to the left and to the right, the total luminous flux and optical efficiency both decrease.According to the numerical simulation for the thermal properties of the cavity type of trough solar collector by the software of Fluent, the following conclusions can be got: With the increase of the directing solar irradiance, the reflectivity of the paraboloid and the absorptivity of the receiver, the thermal power and the thermal efficiency both increase. With the increase of the reflectivity of the paraboloid and the absorptivity of the receiver, the thermal power and the thermal efficiency both decrease. With the increase of the cavity shadow length, the thermal power and the thermal efficiency show a downward trend after first increase. The thermal efficiency for different cavity displays descending highest five tube layouts were: focus placed at the bottom, surround cavity placed, placed at the bottom of the dispersion, placed along the bottom row and bottom row insert placed. With the increase of the inlet velocity of the working fluid, the thermal power and the thermal efficiency show a downward trend slowly after first decrease rapidly. With the increase of the length of the tube, and the thermal efficiency and the thermal power are proportional to the linear increase and then remain unchanged. The thermal power and the thermal efficiency of the nano-fluids is significantly higher than water and HTF. With the increase of the volumetric ratio of the nano-fluids, the thermal efficiency and the thermal power are proportional to the linear increase. With the increase of the particle size of the nano-fluids, the thermal power and the thermal efficiency both increase. The thermal power and the thermal efficiency of the nano-fluids of Cu-HTF are higher than those of the nano-fluids of Cu-water. Take the y-z axis as the center plane, with the incident angle along the z axis increasing both to the left and to the right, the thermal power and the thermal efficiency show a downward trend after first increase. Take the x-y axis as the center plane, with the incident angle along the y axis increasing both to the left and to the right, the thermal power and the thermal efficiency both decrease.Besides, according to the orthogonal analysis for the optical efficiency and the thermal efficiency of the cavity type of trough solar collector, the following conclusions can be got: The eight factors’ decreasing order which affect the optical efficiency are the angle of incidence of light along the z axis, the angle of incidence of light along the x axis, the reflectivity of the paraboloid, the distance from the paraboloid to the receiver, the absorptivity of the receiver, the opening width, the diameter of the circle and the directing solar irradiance. The six factors’ decreasing order which affect the thermal efficiency are the angle of incidence of light along the z axis, the reflectivity of the paraboloid, the angle of incidence of light along the x axis, the directing solar irradiance,the absorptivity of the receiver,the distance from the paraboloid to the receiver.