| Summary: | 博士 === 國立清華大學 === 工程與系統科學系 === 105 === The objected of this paper is propose using capillary pumped loop (CPL) and two-phase closed loop thermosyphon (TPCLT) applied to a solar water heater. Experimental investigation of performance of CPL and TPCLT in different condition. Due to those devices are high-efficiency heat transfer device capable of transporting thermal energy over long distances without the need for other mechanical forces, such as pumps. This makes CPL and TPCLT particularly suitable for applications involving solar water heaters and apply on the building integrated solar water heater.
First, we presents an experimental examination of a railing-type collector solar water heater, employing a CPL as a heat transfer device. The structure and characteristics of the CPL solar water heater are also outlined. We conducted various experiments to investigate the start-up behavior and thermal storage efficiency under various filling ratios with different heat loads and tilt angles. Experiment results revealed that 70% is the ideal filling ratio for a CPL and that the heat load presents critical limitations with regard to stable operations. The highest thermal storage efficiency obtained in this study was 77%. We also determined that when a railing-type collector has a non-zero tilt angle, loose limitations pertaining to heat load can be relaxed without sacrificing stable operations.
The first experiment results show that the fill ratio of the working fluid has a critical impact on the performance and start-up time of TPCLTs. Our objective in this work was to increase the performance of TPCLT solar water heaters by using an evaporator with a porous wick structure (PWS), especially in low heating power. Our results demonstrate that employing a PWS within the evaporator can enhance efficiency by 12.7% and decrease start-up time by 26.5% under low heating power.
The above experiment setup all use small scaler solar water heater and operating in laboratory environment. Therefore, we designed the larger scaler TPCLT solar water heater and operating in laboratory environment and outdoor environments. In laboratory environment, the results shows that the efficiency is 69% in filling ratio 70% with heating power 630W. The efficiency is 63% in filling ratio 60% with heating power 630W. When the system is in filling ratio 70%, the lowest start-up heating power is 270W. When the system is in filling ratio 60%, the lowest start-up heating power is 180W. In outdoor environment, the water temperature can reach 42 OC.
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