Experimental and numerical investigation of driving potential of biomass-pellet hot air generator for coupling with absorption heat pump

Abstract

This paper presents a numerical and experimental study of a heating system that consists of hot air generator driven by biomass pellet burner to drive the NH3-water absorption heat pump made by Robur. The aim of this work is to fully test the system of hot air generator for thermal potential, by developing a thermal field, while driving the absorption heat pump of medium capacities for residential purposes, and to make model of predicting the efficiencies of heating comparing to conveyed heat in desorber of absorption heat pump. Numerical simulations of the hot air generator were performed in the commercial software ANSYS FLUENT and CFX. The experimental part was carried out in the laboratory of the Faculty of Mechanical Engineering in Nis, where the temperature and velocity measurements were obtained and compared to numerical results. Results were obtained for mass air-flow through the hot air generator and desorber of 0.17 and 0.2552 kg/s, pellet burner power of 15 kW, 18 kW, 21 kW, 24 kW, 27 kW, and 30 kW, with air inlet temperature in desorber of around 89-140?C. The heating efficiency of the absorption heat pump goes from 1.01 to 1.37. The heat loss over the surfaces of hot air generator goes from 0.6-0.9 kW depending on ambient air and surface temperatures. The system has the potential to be applied in low temperature heating and the spare heat from combustion products and residual hot air can be used for different purposes.