研究目的
To present a new method for calculating the nominal operating cell temperature (NOCT) of photovoltaic thermal (PVT) modules with water as the working fluid, which depends on the mass flow rate and inlet temperature of the working fluid in the module.
研究成果
The study developed a new method for evaluating the NOCT of PVT modules, which depends on the incident solar irradiance, ambient temperature, fluid mass flow rate, and inlet temperature. The method is practical and only requires the module heat removal factor, optical efficiency, and overall heat loss coefficient of the PVT module, which can be determined in the same manner as those of solar thermal collectors. The calculated PVT module temperature and electrical output agree well with the experimental data, with over 96% of the calculated results having deviations within ±10% from the experimental data.
研究不足
The study was conducted under specific conditions (clear-sky days in Chiang Mai, Thailand) and may not be applicable under all weather conditions. The method requires knowledge of the module heat removal factor, optical efficiency, and overall heat loss coefficient, which may not be readily available for all PVT modules.
1：Experimental Design and Method Selection:
The study involved testing four unglazed identical PVT modules in series outdoors with various mass flow rates. The tests were similar to solar collector tests and were conducted from 8:30 to 16:30 on clear-sky days in Chiang Mai, Thailand. The water inlet temperature of the first PVT module of the system was varied from 27 to 60 ?C.
2：Sample Selection and Data Sources:
The tests were performed on four identical unglazed 200 Wp PVT modules installed in series on a roof facing south with an 18? inclination angle toward the latitude of Chiang Mai.
3：List of Experimental Equipment and Materials:
The experimental equipment consisted of a closed-loop system connected to a 220 L water storage tank with water circulation based on a water pump. A flow meter was installed to measure the water flow rate, and a ball valve was used to adjust the flow rate. A set of K-type thermocouples were installed at the inlet, outlet, and surface of each PVT module, and the temperature values were recorded by an 8-channel data-logger S220-T8. An MS-602 pyranometer aligned with the inclined plane of the PVT module was connected to a Hukseflux LI19 data logger to measure the solar radiation intensity on the PVT plane.
4：An MS-602 pyranometer aligned with the inclined plane of the PVT module was connected to a Hukseflux LI19 data logger to measure the solar radiation intensity on the PVT plane.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The NOCT test was performed in the open-circuit mode, meaning the PVTs were not connected to an external load. The first PVT module was connected to a solar analyzer Prova 210 with a maximum current of 12 A. The solar analyzer scanned the operating current of the PVT module from zero to the short-circuit current every 5 min.
5：Data Analysis Methods:
The correlation between the NOCT of the unglazed PVT module, based on (Tfi ? Ta)/IT, and the water mass flow rate, ˙m, was determined. The calculated PVT module temperature was compared with the experimental data.
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