The influences of recycle effect on double-pass V-corrugated solar air heaters

The study of the heat transfer enhancement for the recycling double-pass V-corrugated solar air heaters, which implement the external recycle of flowing air, was investigated experimentally and theoretically. The comparison among different designs of V-corrugated, baffled and fins attached, and flat-plate collectors was made to show the device performance improvement with various operating parameters under the same working dimensions. The recycling double-pass V-corrugated device developed here was proposed in aiming to strengthen the convective heat-transfer coefficient and enlarge the heat transfer area. The error analysis of experimental results deviate by 0.85–2.46% from the theoretical predictions with the fairly good agreement, and both results show that the device performance of the recycling double-pass V-corrugated operation is better than those of the other configurations under various recycle ratios and mass flow rates. The suitable selections were obtained for operating recycling double-pass V-corrugated devices while considering with an economic viewpoint by both the collector efficiency enhancement and the power consumption increment.