| Title |
Theoretical Analysis of the Flow and Thermal Performance of Solar Water Heaters with Natural Circulation |
| Authors |
Hee Won Lim ; Wang Je Lee ; U Cheul Shin |
| DOI |
https://doi.org/10.6110/KJACR.2021.33.5.209 |
| Keywords |
평판형 태양열집열기; 자연순환; 태양의존율; 태양열온수기; 열사이펀; 트랜시스 Flat-plate solar collector; Natural circulation; Solar fraction; Solar water heater; Thermosyphon; TRNSYS |
| Abstract |
This study presents a theoretical analysis of the dynamic behavior and thermal performance of a solar water heater with an internal exchanger using a thermosiphon system. The heat exchanger, made of a helical coil, is placed in the horizontally cylindrical storage tank so that the solar hot fluid crosses a significant mass of stored water. In order to analyze the dynamic natural circulation of solar water heaters by thermosiphon, a new TRNSYS component was developed using W-language, based on a detailed mathematical model. As a result of simulation, the solar heat yield and the average solar fraction were 2,001 kWh and 75.1%, respectively. The lowest solar fraction in January was 50.5%, and then gradually increased, reaching almost 100% from May to September. Here, when the system overheating lower limit temperature is set to 90℃, it was exposed to the overheating period for about 153 hours, which is 6.5% of the annual operating time (about 2,339 hours). Secondly, the instantaneous maximum efficiency of the collector was 42.3%, and the annual average system efficiency considering the heat loss of the solar storage tank was 36.2%. |