Research On The Performance Of Deep Space Radiant Refrigeration Heat Exchanger

As a new energy material,radiant refrigeration materials have received widespread attention as soon as they were proposed,and have gradually developed from the traditional nighttime radiant refrigeration to a level that can be used under the sun during the day.However,the heat transfer problems that need to be solved in the engineering application of radiant refrigeration materials,especially the heat transfer model under the sun during the day,need to be further explored and improved.This article mainly studies the engineering application of a deep space radiant cooling heat exchanger with a certain tilt angle to the north under the sun during the day.For this kind of engineering application,the heat transfer model of the radiant heat exchanger coated with radiant refrigeration material when tilted to the north was proposed;the experimental device with different tilt angles to the north was built,and the continuous operation was carried out day and night in an outdoor environment.Experimental Study.The heat exchange performance of the radiant refrigeration heat exchanger in the outdoor environment under 7 working conditions is analyzed experimentally.Comparing the solar radiation heat gain,surface radiation heat exchange,outdoor air convection heat exchange,deep space radiation heat exchange in the universe,sky Changes in radiant heat transfer,as well as changes in the value of heat gain and loss of radiant refrigeration heat exchanger and the proportion of the value at a typical time.Secondly,the working performance of radiation refrigeration heat exchanger coated with radiation refrigeration materials,uncoated radiation refrigeration heat exchanger and radiation refrigeration heat exchanger with changed internal structure is compared when the parameters such as solar radiation heat gain,surface radiation heat transfer,outdoor air convection heat transfer,cosmic deep space radiation heat transfer and sky radiation heat transfer change.This paper also studies the combination of radiant refrigeration heat exchanger and photovoltaic cells to form a photovoltaic radiation system,and conducts comparative experiments with ordinary photovoltaic systems.Through the analysis of the above experimental data,the main conclusions of this paper are as follows:（1）The energy balance heat transfer model of the outdoor radiant cooling heat exchanger inclined to the north is proposed.In this experiment,the error between the experimental test results of the radiant refrigeration heat exchanger inclined to the north at different angles and the model prediction result is less than 8%.The heat transfer model can be used for the heat transfer research of the radiant refrigeration heat exchanger inclined to the north..（2）Under the experimental conditions,（1）As the intensity of solar radiation gradually decreases,the overall solar radiant heat absorbed by the radiant refrigeration heat exchanger shows a gradual decrease,and as the angle of the radiant refrigeration heat exchanger tilts toward the north gradually Increase,the heat absorbed by the heat exchanger also shows a gradual decrease;（2）The radiant heat transfer from the surface to the surface of the radiant cooling heat exchanger gradually increases with the increase of the inclination angle,because the surface temperature is always higher than the plate surface temperature,So it has been transferring heat to the surface of the heat exchanger.This has the same regularity as the angle between the radiant refrigeration heat exchanger and the ground;（3）Due to the uncertainty of outdoor air flow under different working conditions,the different angles of the radiant refrigeration heat exchanger to the north have no obvious effect on the amount of convective heat transfer.（4）With the increase of the angle of the radiant refrigeration heat exchanger to the north,the radiative heat exchange between the radiant refrigeration heat exchanger and the deep space and sky of the universe gradually decreases,and both are dissipating heat outward.In addition,the heat exchange between the radiant refrigeration heat exchanger and the deep space in the daytime fluctuates more than at night.The effective sky temperature has a significant effect on the radiant heat exchange between the surface of the radiant cooling heat exchanger and the sky.（5）For the radiant heat exchanger coated with radiant refrigeration material used in this experiment,the radiant refrigeration heat exchanger inclined at 30° to the north is the optimal angle under the experimental conditions.（3）Compared with changing the internal structure of the radiant cooling heat exchanger,the surface material of the radiant cooling heat exchanger affects the heat exchanger’s acceptance of solar radiation heat,surface radiation heat exchange,outdoor air convection heat exchange,deep space radiation heat exchange,The more important factor of sky radiation heat transfer.（4）Designed and built a photovoltaic radiation system composed of radiation heat exchangers and photovoltaic panels.Under the working conditions of this experiment,the surface temperature of the photovoltaic panel of the photovoltaic radiation system showed an overall downward trend,and the temperature difference between the panel surface temperature of the ordinary photovoltaic system was gradually increased,and the maximum temperature difference reached 2.06℃.In one hour,the average photoelectric conversion efficiency of the photovoltaic radiation system is 14.52%,which is 0.65% higher than the average photoelectric conversion efficiency of the ordinary radiation system of 13.87%.