Modelling Polygeneration with Desiccant Cooling System for Tropical Climates
Maintaining comfortable indoor conditions in industrial environments incur high energy bills due to heavy dependency on electrically operated air conditioning systems. Recent research suggests that desiccant cooling concept could help maintain satisfactory indoor conditions at relatively lower energy consumptions. The desiccant cooling technique uses low temperature or low grade heat to drive the cooling cycle; it works without the use of refrigerants. As such, desiccant cooling appears a logical supplement for space cooling applications in tropical climates.
This research presented is conducted to evaluate the performances and applicability of desiccant cooling systems under the local climatic conditions. Particularly, two operating modes; ventilation and recirculation modes, of solid desiccants based open cycle air conditioning systems that use waste heat are analysed to understand their operating ranges, performances and applicability in the local context. The heat and mass transfer process of desiccant system is modelled using the first principles and a software tool developed based on this theoretical background, known as TRNSYS is used as the main tool of analysis.
Preliminary results obtained for weather data for Colombo shows 0.95 and 1.02 optimum coefficients of performance of the ventilation mode and for the recirculation modes respectively when heat is available at 85 ºC. Based on comparisons of the analysis it is seen that the recirculation mode show better performance than ventilation mode, hence a cooling system suitable in tropical weather is proposed on recirculation mode for a case study in Sri Lanka.