CAJ | 학술논문

为了研究槽式太阳能集热器的传热特性及为槽式太阳能集热器的设计提供理论依据，该文分析了槽式太阳能集热器的传热特点，建立了槽式太阳能集热器传热过程一维数学模型；利用该数学模型，计算分析了槽式太阳能集热器的传热特性。选取了2014年9月21日、10月25日的太阳直接辐照数据进行计算分析，10月25日太阳直接辐照数据均值比9月21日高37.5894 W/m2，9月21日集热器吸收的太阳辐射热能计算均值比10月25日高196.644 W/m；接受管内外壁导热量随内外壁面温差升高而增加，接受管外径与内径的比值大于1.05时导热热阻增加到0.0004679 K/(W·m)；接受管和玻璃管之间传热主要是辐射换热，辐射换热量随玻璃管内壁面温度升高而增加；对流换热量数值上可以忽略不计，且与接受管和玻璃管之间的环形空间残存气体类型有关，环形空间为氢气的对流换热量大于空气，空气大于氩气；玻璃管对外界的传热主要是辐射换热和对流换热，环境温度每下降10℃，玻璃管对环境的辐射放热量增加约105 W/m；玻璃外管壁温度为50℃时，风速为6 m/s比0.5 m/s时的对流换热量增加约116 W/m，玻璃外管壁温为80℃时，该值增加约为340 W/m；集热器的瞬时热效率随传热工质温度的升高而下降，随太阳直接辐照增加而升高；利用该文建立的数学模型计算的瞬时效率与美国可再生能源实验室的试验数据最大偏差约为3%。
위료연구조식태양능집열기적전열특성급위조식태양능집열기적설계제공이론의거，해문분석료조식태양능집열기적전열특점，건립료조식태양능집열기전열과정일유수학모형；이용해수학모형，계산분석료조식태양능집열기적전열특성。선취료2014년9월21일、10월25일적태양직접복조수거진행계산분석，10월25일태양직접복조수거균치비9월21일고37.5894 W/m2，9월21일집열기흡수적태양복사열능계산균치비10월25일고196.644 W/m；접수관내외벽도열량수내외벽면온차승고이증가，접수관외경여내경적비치대우1.05시도열열조증가도0.0004679 K/(W·m)；접수관화파리관지간전열주요시복사환열，복사환열량수파리관내벽면온도승고이증가；대류환열량수치상가이홀략불계，차여접수관화파리관지간적배형공간잔존기체류형유관，배형공간위경기적대류환열량대우공기，공기대우아기；파리관대외계적전열주요시복사환열화대류환열，배경온도매하강10℃，파리관대배경적복사방열량증가약105 W/m；파리외관벽온도위50℃시，풍속위6 m/s비0.5 m/s시적대류환열량증가약116 W/m，파리외관벽온위80℃시，해치증가약위340 W/m；집열기적순시열효솔수전열공질온도적승고이하강，수태양직접복조증가이승고；이용해문건립적수학모형계산적순시효솔여미국가재생능원실험실적시험수거최대편차약위3%。
Parabolic trough solar collector (PTC) is one of the most mature technologies in the medium and high temperature solar thermal utilization field, and PTC is the key component which transforms solar radiation into heat. PTC performance directly affects the performance of solar energy heat utilization system. In order to improve the thermal efficiency and provide the theoretical basis for PTC design, this paper analyzes the heat transfer characteristics of PTC. One-dimensional heat transfer mathematical model of PTC is established, and using this model, heat transfer characteristics for PTR70 2008 type PTC are analyzed. The result shows solar radiation heat absorbed by PTC is significantly affected by the solar incident angle. Heat absorbed by PTC is calculated by direct normal irradiance data in September 21st and October 25th, and the mean direct solar radiation data of October 25th is higher than the data in September 21st by 37.5894 W/m2, solar radiation heat absorbed by PTC in September 21st is higher than the data in October 25th by 196.644 W/m. The heat transferred from the outer absorber surface to the inner absorber surface increases with the increase of temperature difference of the outer and inner absorber surface, decreases with the increase of the ratio of outer absorber diameter to inner absorber diameter. When the ratio of outer absorber diameter to inner absorber diameter is greater than 1.05, the thermal resistance increases to 0.00046-0.00047 K/(W·m). Convection and radiation heat transfer occur between the absorber and the glass envelope. The heat transferred across the evacuated annulus from the outer absorber surface to the inner glass surface through radiation increases with the increase of the temperature of the outer absorber surface. The convection heat transfer between the absorber and glass envelope is very small and plays a negligible role. The heat is associated with annulus gas type, and heat transfer of annulus hydrogen is greater than annulus air and heat transfer of annulus air is greater than annulus argon. The heat transfers from the glass envelope to the atmosphere by convection and radiation. The convection will either be forced or natural, depending on whether there is wind. Radiation heat loss occurs due to the temperature difference between the glass envelope and the sky. Radiation heat loss increases by 105 W when ambient temperature drops by 10℃. The convection heat increases by 116 W when wind speed increases from 0.5 to 6 m/s under the glass envelope outer surface temperature of 50℃. The value reaches 340 W when the glass envelope outer surface temperature is 80℃. The transient thermal efficiency of PTC is significantly affected by heat transfer fluid (HTF) temperature. The transient thermal efficiency decreases with the increase of the temperature of HTF, and increases with the increase of the direct solar radiation. PTC thermal efficiency is calculated by using the mathematical model established in this paper, and compared with the experimental data of the national renewable energy laboratory (NREL) in America, and the results show that the maximum deviation is about 3%. It shows that the mathematical model can reflect the heat transfer law of PTC. The characteristics of heat transfer mathematical model can provide theoretical basis for PTC design and system operation.