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A multistate investigation of a solar dryer coupled with photovoltaic thermal collector and evacuated tube collector
摘要： In this study, an indirect solar dryer was designed and manufactured using a Photovoltaic Thermal (PV/T) collector and Evacuated Tube (ET) collector. The main objectives of this system were to supply the thermal load of the indirect solar dryer, to ?nd the best model for the drying process, to present a new model to predict the drying process of Tarkhineh (the drying material) and to perform its life-cycle cost analysis (LCCA). The manufactured system was tested under the weather conditions of Sanandaj city, Iran and was compared with open sun drying. When the auxiliary heater was not used, the new model 1 was the best model to describe the drying of Tarkhineh in the open sun mode and the new model 2 was the best model to describe the drying of Tarkhineh in the solar dryer designed and manufactured in this study. The new models 1 and 2 were found to be the best models for describing the drying process of Tarkhineh at set point temperatures 55 °C and 45 °C, supplied by the auxiliary heater, respectively. The payback period of the PV/T solar dryer and ET solar dryer, assuming 300 sunny days/year, were 2.3 and 2.5 years, respectively.
关键词： Evacuated tube collector,Photovoltaic thermal (PV/T) collector,Payback period,Tarkhineh,Models of drying,Solar dryer
更新于2025-09-23 15:21:01
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A new version of a low concentration evacuated tube solar collector: Optical and thermal investigation
摘要： This work is focused on investigating the performance of a new version of evacuated tube solar collector with and without solar tracking system. The evacuated tube solar collector is composed of an absorbing copper tube positioned eccentrically inside a transparent glass cover tube which has a reflective film insert on its inner surface and vacuum in eccentric annular space. Modeling of the proposed evacuated tube collector is based on the conservation equations of mass, momentum and energy and discretized by using the finite volumes method. A home-built numerical code is developed, tested and its grid size optimized. This code is validated against available experimental and numerical results. Effects of the tilt angle and tracking systems are also evaluated. The results showed maximum and minimum daily efficiencies of the collector of about 73% and 42%, respectively. The annual efficiency of this collector was evaluated as 61.5% for the city of S?o Luís, Brazil. The new contributions from the present work include the reflective film, the eccentricity of the absorber and the presence of vacuum in the annular space. The reflective film helps to keep the absorber at uniform temperature and reduce thermal induced stress. The eccentricity is introduced to create concentration effect which helps to increase the outlet temperature of the working fluid and reduce the mass of the collector system. The presence of vacuum in the eccentric annular space reduces effectively the thermal losses, improves the efficiency.
关键词： Solar energy,Eccentric evacuated tube collector,Evacuated tube solar collector,Solar tracking systems,Collector modeling
更新于2025-09-19 17:15:36