Application of solar assisted heating and desiccant cooling systems for a domestic building

The performance of solar assisted heating and desiccant cooling systems for a domestic two story residence located in Baghdad was evaluated. A computer simulation was developed to assess the effects of various designs and operating conditions on the performance of the system and its components. The solar air heating system included a V corrugated solar air heater array, a rock bed storage unit and an auxiliary heat source. A rotary silica gel desiccant dehumidifier, a sensible cooler and an evaporative cooler were added to the above system to form an open cycle solar assisted desiccant cooling system. The variable base degree-day method was employed in order to incorporate the hourly variations of solar heat gain and internal heat gains of the space in the estimation of the heating load. The transfer function method was used to evaluate the hourly variation of the cooling load. Only two collector rows in series were employed to provide the required supply air temperature for the heating system and the required regeneration temperature for the desiccant cooling system. This array gave an air outlet temperature of approximately 62 degreesC at an air mass flux of 0.06 kg/s m(2) at midday in July, while a 36 degreesC outlet air temperature was achieved for the same array and mass flux in January. The results of simulation of the solar air heating system indicated that the major design parameter is the collector area. The effect of air mass flux through the collector array was not significant. Also, increasing the rock bed storage volume produces only slight improvements in the solar fraction. Simulation of the open cycle solar assisted desiccant cooling system showed that the ambient temperature, regeneration temperature, heat exchanger effectiveness and evaporative cooler effectiveness have major influences on the system performance, whereas the dehumidifier has a minor effect. Also, the simulated system was capable of providing a cool supply of air at acceptable comfort conditions for various summer days in Baghdad. (C) 2001 Elsevier Science Ltd. All rights reserved.