Exergoeconomic analysis of recyclic packed bed solar air heater- sustained air heating system for buildings

In the present investigation, the energy and exergy efficiencies of double pass packed bed solar air heater under external recycle have been investigated, theoretically and experimentally. An analytical model capable of predicting the energy and exergy efficiencies is presented. The thermohydraulic efficiency criterion is also used to optimize the input parameters. It is observed that the energy efficiency of the heater increases with increasing mass flow rate and recycle ratio whereas, the exergy efficiency increases with an increase in the mass flow rate and the recycle ratio, but attains a maximum value and subsequently decreases with further increase in the mass flow rate and the recycle ratio. The optimum values of the mass flow rate to yield the maximum value of the energy and exergy efficiencies are found to be 0.025 kg/s and 0.006 kg/s, respectively, while the recycle ratio is found to be about 1.5 for both. In addition, the cost per unit energy delivered by the heater is also calculated. At the optimum value of input parameters; the heater's cost per unit energy delivery is 0.78 Rs/kWh and Rs. 0.58 Rs/kWh, respectively, on the basis of both energy and exergy gain.