تحليل وتقييم الأداء الحراري لنظام تثاقلي لتسخين المياه بالطاقة الشمسية في مدينة دمشق

Thermal Performance Analysis and Assessment of Thermosyphon Solar Water Heater in Damascus

Abstract

Natural circulation system (Thermosyphon) solar water heating systems are the most suitable option for securing domestic hot water. In thermosyphon systems, the tank is located above the solar collector, and the heat transfer medium circulates between the collector and the tank by thermal buoyancy, eliminating the need for the pump and problems associated with maintenance and securing the required electrical energy for its operation. The research aims to analyze and evaluate the performance of a thermosyphon solar heating system in Damascus. In order to achieve that, we adopted two methods. The first is a modified form of the computational F-chart method that is suitable for a thermosyphon solar heating system with variable flow, and this method allows calculating the optimal area of ​​the flat solar collectors for a specific hot water load. The second method is simulating the system in TRNSYS environment, which allows studying the thermal performance of system at hourly climate changes throughout the year. Results showed that the optimal area for the solar collectors securing a domestic hot water load of (300 L/day) with a temperature of 60 ˚C is (4 m²). The thermosyphon solar system can secure about (50-98%) of the required domestic heating load in Damascus according to the month studied, the annual solar fraction averaged (80%) and the thermal efficiency of the solar collector is about 50%. The results also showed that the thermosyphon system ensures the stability of temperatures in thermal storage tank for a long period of time, which increases the efficiency of system. We also made a comparison of the results of computational method with the results of simulation, and the percentage of error in the solar fraction was within acceptable limits for all months throughout the year.