23 September 2011


An advanced solar air conditioning system for commercial use was developed and the system has been demonstrated in one of branch offices of Tokyo Gas. Features of the system are (1) a single/double effect combined absorption chiller utilizes solar hot water by priority in single effect cycle and the consumption of natural gas that is for double effect cycle is minimized, (2) to reduce heat capacity and heat loss, the system has no buffer tank, and (3) a
developed controller minimizes the electric consumption of the solar hot water pump and enhances the collector efficiency by measuring the condition of the absorption chiller and the hot water temperature. Through the demonstration, (1) the absorption chiller was driven only by the solar hot water when the air conditioning demand was low, (2) the temperature of the
chilled water was stable by the control of the back-up gas burner of the absorption chiller, and (3) the pump was operated only when the solar hot water temperature reaches high enough
but as low as possible to drive the absorption chiller. The volume of CO2 emission was reduced by about 18% from April to December 2010, compared with the conventional system.