SIMULATION OF SOLAR AIR HEATING AT CONSTANT-TEMPERATURE

Solar space heating with warm air in typical air collectors and rock b ed storage systems involves constant air now rates and varying the tem perature of supply to roams and to storage. This practice results in u ndesirable fluctuations in comfort levels in the living space, excessi ve storage size, useful but inaccessible heat in storage, and unnecess arily high energy consumption for air circulation and auxiliary heat. These drawbacks can be avoided by use of a practical controller and va riable speed fan to provide heated air from the collector at constant temperature and a continually varying now rate. Collector manufacturer 's data, confirmed by seasonal tests on a solar air heating system in Solar House II at Colorado State University, have been used in simulat ions at constant hot air supply temperatures of 40 degrees, 50 degrees , and 60 degrees C, and at one typical constant flow rate of 49 kg/h p er m(2) through a 50 m(2) collector and rock bed storage unit, providi ng approximately half the seasonal heating requirements of a residenti al building. Auxiliary heat requirements and fan power use in the 40 d egrees C and 50 degrees C constant temperature operations were signifi cantly reduced from the levels prevailing under constant flow conditio ns. Collection efficiency and solar heat supply at constant now were s lightly higher than values at the 60 degrees C constant temperature le vel.