Solar/Gas Water Heater Characterization and Development

摘要

An experimental and analytical study was completed which comparatively characterized current options for solar/gas water heaters and which identified and evaluated avenues to improvement. Both solar and conventional water heaters were tested in order to understand the unique qualities which differentiate generic designs. Results of testing were used to modify and validate computer simulations describing their performance. With little exception, modeling was accomplished using the TRNSYS computer program with modifications. The program ultimately relied upon life-cycle cost analysis to evaluate the systems. Energy usage was derived from annual system performance simulations using TRNSYS and costs for equipment and energy as well as predictions of future trends such as escalation rates were derived from other sources. The major performance obstacle to efficient gas backup for solar was identified as standby losses in the center-flue design. The major economic obstacle to combined system success was identified as the installed cost of the solar system. Thermosyphon preheat systems, where viable, and direct preheat systems with freeze protection are closest to economic viability.