Experimental study of heat transfer enhancement in the evaporator of single-effect absorption chiller using new different tube insert

In this paper, the effect of the different tube inserts with various geometry parameters on turbulent flow in the evaporator of single-effect absorption chiller has been investigated experimentally. The experiments were performed with several tube inserts including of wire coils (S1, S2), modified wire coils (GS1, GS2, GS5), modified classic (TW) and butterfly (BT) for mass flow rate from 0.167 to 0.583 kg s-1. In all cases, the use of tube inserts leads to a considerable increase in heat transfer and pressure drop over the evaporator without tube insert. The highest performance factor of 1.78 was achieved for the butterfly tube inserts compared to others. In all cases and all Reynolds number, the performance factors are more than one and these techniques are favorable for heat transfer enhancement.