METHOD FOR CONTROLLING OF DRAIN DOWN-TYPE CLOSED LOOP SOLAR ENERGY SYSTEM HAVING WAITING CONDITION

摘要

PURPOSE: A drain down type closed solar system having a stand-by mode and a control method thereof are provided to reduce the driving power for a pump and improve the operation stability of the system. CONSTITUTION: A control method of a drain down type closed solar system having a stand-by mode is as follows. The difference between the temperature(T1) measured by a first temperature measuring unit of a solar heat collector and the temperature(T2) measured by a second temperature measuring unit of a heat storage tank is compared with a pre-set temperature difference(S101). When the measured difference is greater than the pre-set temperature difference, a thermal medium is normally circulated(S102,S103). When the measured difference is less than the pre-set temperature difference and the temperature measured by the first temperature measuring unit is over the pre-set maximum temperature, the circulation of the thermal medium is stopped and the thermal medium is collected through a drain down pipe to a thermal medium reservoir(S104). When the temperature measured by the first temperature measuring unit is less lower than the pre-set maximum temperature, a stand-by mode is activated so that only the circulation of the thermal medium is stopped and drain down is not performed.