Modelling and control optimization of a solar desiccant and evaporative cooling system using an electrical heat pump

The aim of this work is the control optimization of a new solar assisted air-conditioning concept which combines a desiccant and evaporative cooling (DEC) system with an electrical heat pump. The DEC air handling unit configuration had to prevent return air from mixing with supply air. Therefore, a flat plate sensible heat exchanger is used instead of a rotary. Moreover an additional stream of outdoor air is used for the desiccant wheel regeneration. A reversible water/water heat pump is also included in the system. In summer, the heat pump cools the supply air stream and pre-heats the regeneration air when dehumidification is needed; in winter, the heat pump provides auxiliary heat if a minimum temperature is available in the heat storage, otherwise a backup boiler is used. The depicted system has been modelled and an extensive simulation work has been carried out in order to verify the control capability during the different operation modes. As a result an optimal control strategy has been identified. According to simulations, the system can deliver primary air at the requested temperature and humidity while holding the overall electricity consumption at significant low levels compared to reference system solutions.