Performance Research On Compound Parabolic Concentrator For Building Heating System

With the development of economic and the acceleration of industrialization process,the energy consumption of buildings,industries,and transportation has increased,which brings the problem of increasingly consumption of global fossil energy.Then the utilization of clean,non-polluting solar energy for building heating system is one of the effective ways to reduce the total energy consumption ofbuildings,especially in the northwest of china with sufficient solar energy.The traditional plate collectors,vacuum tube collectors and so forth have low collection temperatures in the operating of cold regions' winter.Apart from this,these collectors has other drawbacks,such as easily burst,have low thermal efficiency,and cover large area of land.However,the application of new type of solar concentrating and collection technology can improve the drawbacks of the solar concentrators which have mentioned above.In order to overcome the shortcomings,a Compound Parabolic Concentrator(CPC)for building heating system is proposed in present paper,which has a high collection temperature,low requirements for tracking accuracy,and can absorb some scattered lights.The device has a simple structure,is easy to maintain,and can be applied in the energy saving buildings during the cold winter.This paper introduces the structure and working principle of a trough Compound Parabolic Concentrator for building heating system.During the process of the study,optical simulation software was used to compute and analyze the concentrator's light-collecting characteristics with different incident angles and different installation angles.The results indicate that the light convergence rate of the concentrator is 66.99% when the incidence declination ? is 6°,and the convergence rate of the concentrator is still 85.71% when the installation deviation angle? of the panel receiver is 80°.Based on the lighting analysis results,a trough Compound Parabolic Concentrator for building heating system experimental platform was built in Hohhot,Inner Mongolia province.In order to test the photo-thermal performance of the Compound Parabolic Concentrator,the device was installed on the roof of an independent energy-saving building.The experiment results indicate that the maximum temperature difference between the concentrator's inlet and outlet oil is about 20? in the case of normal incidence under the sunny condition;under the cloudy condition,with the change of the solar irradiance,the temperature fluctuation of the concentrator's outlet oil is relatively flat,and in the case of incidence under the condition of different title angles,the maximum temperature difference between the concentrator's inlet and outlet oil is 20.72?.A trough Compound Parabolic Concentrator concentrating solar energy building heating system thermal performance test bench was built to analyzes the oil mass flow rate'sinfluence on the system's thermal efficiency and monitor the indoor and the each test point temperatureof the system under continuous operating condition.The results indicate that with the increase of the mass flow rate of the heat transfer oil in the circulating pipe,the thermal efficiency of the system decreases.In the case of the electrical auxiliary is off under the condition of the continuous operation of the system,the indoor atmosphere temperature can reach a maximum of 16.85 °C at night.At last,the paper developed a economic analysis of the system.The payback period of the experimental system is11 years.