하이브리드 집열기 공기채널 내 전열촉진체 형상에 따른 열적성능에 관한 수치해석 연구

Abstract

As a part of the effort for increasing usage of solar thermal energy, the research about hybrid solar collector that can heating air and liquid simultaneously has been conducted. In the previous study, the performance like temperature difference, heat transfer rate, thermal efficiency was investigated when this collector was heating air and liquid respectively and simultaneously. From these previous studies, the necessity for enhancing the air heating performance was confirmed and it was considered to achieve the improvement of air heating performance by changing of obstacles for heat transfer enhancement like a fin can be achieve this improvement. So in this study, numerical analysis was conducted in air channel of hybrid solar collector with various obstacles for heat transfer enhancement from absorb to flow air. As obstacle, v-groove, protrusion, vertical fin was installed and heat transfer and pressure drop was investigated with these obstacles with various conditions of obstacle. As a result, v-groove type and vertical fin was shown higher Nusselt number than traditional fin type, but this increment of heat transfer performance also lead to higher pressure drop represented as friction factor. The performance factor(PF) consider both heat transfer performance and pressure drop was shown higher value with v-groove type. But the vertical fin was shown lower performance factor than traditional type and it means that increment of pressure drop is higher than increment of heat transfer performance compared with traditional fin type. In case of protrusion, it show higher performance factor than traditional fin type. But the heat transfer performance of protrusion is similar with traditional type, so the higher performance factor was come from decrement of pressure drop, not the increment of heat transfer. From these results, v-groove type was considered as appropriate type and it is expected that the improvement of air heating performance can be achieved by applying v-groove obstacle to hybrid solar collector.