A design procedure for solar air heating systems

A natural extension of the design procedure for liquid-based solar space and water heating systems is a similar analysis for solar heating systems using air as the heat transfer fluid. In this paper, a solar air heating system incorporating a flat-plate air heater and packed bed thermal storage is described and a simulation model for the system is developed. The results of many simulations of the air heating system are used to establish the relationship between system performance and the system design and meteorological variables. The results are presented in analytic and graphical form, referred to as an f-chart for solar air heating systems. The results of simulations in several widely different climates suggest that the information presented in the f-chart is location independent. Methods of estimating the performance of air heating systems having a collector air capacitance rate and a storage capacity other than those used to generate the f-chart are included. A comparison of the performance of air and liquid based systems is afforded by a comparison of their respective f-charts. The air system is shown to perform better at high load fractions supplied by solar energy than a liquid-based system with the same collector thermal performance parameters.