Thermodynamics and Economic Analysis of a Two-Stage Desiccant Cooling (TSDC) System Based on Biomass Heating for a Greenhouse Application

Abstract

This paper proposes a novel scheme of biomass regenerated two-stage desiccant-supported greenhouse cooling in the tropical and sub-tropical countries. The system's goal is to provide the ideal thermal environment inside a greenhouse for the growth of different kinds of Orchid. The two-stage desiccant-based cooling is used in the proposed system to obtain a low humidity ratio inside the greenhouse. The desiccant is regenerated using a biomass-based heating system. The first law analysis and the exergy analysis of the system's individual components have been included in the study. The results of the thermal model (greenhouse temperature) have been compared with that of a reference model study available in the literature. With a mean absolute error for the humidity ratio and greenhouse air temperature of 4.3 percent and 4.5 percent, respectively. The model's predictions are in good agreement with the results of the reference model. The performance study of the proposed system reveals that the maximum temperature of the greenhouse air can be limited within the defined values even during July and September, when both the ambient humidity and the temperature are high. The proposed system COPth varies from a minimum of 0.54 to a maximum of 1.02 for a typical hot and humid day of July. The system can exhibit maximum exergy efficiency of 33% in the morning, while the ultimate exergy destruction occurs at the DW1 (39.25%) and regeneration heater (21.69%). The payback period of the proposed system is 8.2 years considering 15 years’ life span.