Development of flat plate collector with plastic transparent insulation and low-cost overheating protection system

In this work a flat plate collector (FPC) with plastic transparent insulation materials (TIM) and a low-cost overheating protection system destined for heat supply from 80 to 120°C is presented. A ventilation channel with a thermally actuated door is inserted below the absorber allowing to protect the collector from stagnation conditions, while preserving good performance during normal operation. This collector is intended to have not only a comparable efficiency with the available commercial collectors but also low cost. For this objective, a prototype has been constructed and experimentally tested and in parallel, a numerical model has been implemented. The proposed numerical model is based on the resolution of the different components of the solar collector by means of a modular object-oriented platform. Indoor and outdoor tests have been performed in order to check the effectiveness of the designed overheating protection system and to validate the model. The comparison of the numerical results with experiments has shown a good agreement. Finally, an extended parametric study is performed in order to optimize the collector design: 3125 different configurations of FPC with TIM and ventilation channel were evaluated by means of virtual prototyping. The results allowed to propose the most promising design of a stagnation proof FPC with plastic TIM able to work at an operating temperature of 100 °C with good efficiency. The design presented in this paper can be considered promising for increasing the thermal performance of FPC and could be used in industrial applications that need heat at low-to-medium temperature level.