Articles written in Sadhana
Volume 40 Issue 7 October 2015 pp 2177-2196
This study simulated active photovoltaic thermal solar collectors (PV/T) for hot water production using TRNSYS. The PV/T collectors consist of the amorphous, monocrystalline and polycrystalline. The long-term performances for the glazed and unglazed PV/T collectors were also evaluated. In this simulation, the design parameters used were collector area of 4 m2, collector slope angle of 15 degree and mass flow rate to the collector area ratio of 8–20 kg/hm2. In addition the tank height between 0.9 m to 1.1 m for unglazed PV/T collectors and 0.9 m to 1 m for glazed collectors, as well as the storage tank volume between 200 and 300 L has been used. The climate parameters used were solar radiation levels range of 4–4.9 kWh/m2, the mean ambient temperature in the range of 25–28°C. The results of the simulation indicated that there was an increase in solar fraction and electrical power output of the active PV/T hot water system.
Volume 41 Issue 8 August 2016 pp 877-886
In this paper, an integrated solar heat pipe wall space heating system, employing double glazed heat pipe evacuated tube solar collector and forced convective heat transfer condenser, is introduced. Thermal performance of the heat pipe solar collector is studied and a numerical model is developed to investigate thethermal efficiency of the system, the inlet and outlet air temperatures and heat pipe temperature. Furthermore, the system performance is evaluated based on exergy efficiency. In order to verify the precision of the developed model, the numerical results are compared with experimental data. Parametric sensitivity for design features and material associated with the heat pipe, collector cover and insulation is evaluated to provide a combination with higher thermal performance. Simulation results show that applying a solar collector with more than 30 heat pipes is not efficient. The rate of increasing in temperature of air becomes negligible after 30 heat pipes and the trend of the thermal efficiency is descending with increasing heat pipes. The results also indicate that at a cold winter day of January, the proposed system with a 20 heat pipe collector shows maximum energy and exergy efficiency of 56.8% and 7.2%, which can afford warm air up to 30°C. At the end, the capability of the proposed system tomeet the heating demand of a building is investigated. It is concluded that the best method to reach a higher thermal covered area is to apply parallel collectors