การศึกษาสมรรถนะของตัวเก็บรังสีอาทิตย์แบบใหม่ที่ใช้วัสดุเปลี่ยนเฟสในท่อไรเซอร์

Abstract

This research aims to study the performance of flat-plate solar collector without phase change material (PCM) and with RT42 PCM type with a melting point at 38-40 oC filled in the riser tube with a diameter of 10 mm and 16 mm that inserted into the absorber tube of 28 mm outside diameter. The experiment flat-plate solar collector has 220 mm of width, 1,000 mm of length, and 100 mm of height facing to the south at 18o of tilt angle at School of Renewable Energy, Maejo University, Chiang Mai, Thailand. The electrical pump is used to circulate water through the collector and measured the mass flow rate by flow rate meter. In the hot water storage tank the electric heater is installed the water temperature regulation. The test method is carried out following the ASHRAE standard 93-2003 in a condition of the solar radiation is equal or more than 790 W/m2, the wind speed is between 2.2-4.5 m/s, the ambient temperature is not more than 30 °C, the inlet water temperature of solar collector is varied from 35°C - 65 °C and has adjusted increment of 5 °C. The three conditions of mass flow rate 0.01 0.02 and 0.03 kg/s•m2 are adjusted. The obtained data would be analyzed the heat transfer and thermal performance of solar collector, respectively. From the experiment showed that the inlet water temperature and mass flow rate effected on the thermal performance of solar collector. When the inlet water temperature increased, the heat gain from solar collector and the thermal performance would be decreased because of the heat gain loss to the surrounding as same as in the case study of mass flow rate increasing. The thermal performance of solar collector integrated with PCM riser of 16 mm diameter at the mass flow rate of 0.03 kg/s·m2 was given the highest thermal performance presented of the and were 0.835 and 9.68 W/m2.K. The next was the solar collector integrated with PCM riser of 10 mm diameter and the last was the conventional solar collector at the mass flow rate of 0.02 kg/s.m2 which showed the are 0.828, 0.713 and were 11.304 W/m2⸱K, 10.642 W/m2⸱K, respectively. For the heat transfer characteristic of solar collector discussion. It was found that the observation of water mass flow rate was a laminar flow. When the mass flow rate and the riser tube increased, the convection heat transfer coefficient would be increased as same as the Prandtl Number. From the study could obtain the relation of Nusselt number (Nu) that relates to the Reynold number (Re) and Prandtl number (Pr) as following equation Nu = 0.143 Re 0.193 Pr 1.821 which 2 < Pr < 5.