Performance assessment of Brine-based Liquid-Desiccant System for greenhouse air conditioning

Abstract

This paper investigates the application of a Brine-based Liquid Desiccant Air-conditioning System (LDAS) for use in greenhouses in Tunisia, aiming to address the energy-intensive nature of conventional climate control methods. Seawater brines from Tunisian Salinas are chosen as cost-effective and environmentally sustainable desiccants, despite challenges associated with brine complexity.

The primary goal of the research is to evaluate the LDAS performance in creating and maintaining a balanced and controlled climate for optimal plant growth while minimizing energy consumption. The experimental setup involves a closed greenhouse, and the study comprehensively assesses the system performance through measurements and calculations of the Equilibrium Relative Humidity (ERH) of the liquid desiccant, heat exchange rates of the LDAS components, and the overall Coefficient of Performance (COP). The methodology integrates both experimental and numerical approaches, utilizing Python programming for thermodynamic parameter analysis. Initial results indicate the promising potential of brine-based LDAS as a sustainable solution for greenhouse agriculture in Tunisia. Hygroscopicity assessments reveal a significant dehumidification capacity of the system, with an ERH range of 33 % to 39.1 %. Greenhouse trials demonstrate the system effectiveness in temperature modulation, humidity control, and the maintenance of an optimal Vapor Pressure Deficit (VPD) conducive to plant growth. The LDAS demonstrates substantial cooling effects in the greenhouse, reducing air temperatures by 5.5 to 23.8 °C with efficient humidity control, thereby achieving a noteworthy COP of 5.81, which exceeds benchmarks set by conventional systems. Despite these achievements, the paper acknowledges nuanced challenges and emphasizes the need for further optimization for consistent climate control in demanding scenarios.