Three Years Experimental Comparative Analysis of a Desiccant-Based Air Conditioning System for a Flower Greenhouse

摘要

This paper presents an experimental comparative analysis of a desiccant-based and a traditional air conditioning system for a flower greenhouse in winter season. Two identical flower greenhouses operating near Bergamo (Italy) have been equipped with a traditional and an innovative air conditioning system respectively. The innovative air conditioning system, which is added to the conventional equipment in one of the greenhouses, is based on the Ventilated Latent Heat Converter (VLHC) AGAM 1020 basically working with H_2O-LiCl desiccant. The VLHC system consists of an integrated dehumidification and regeneration unit. In the dehumidification part the strong solution absorbs the ambient air humidity. Heat recovery is performed on the desiccant regeneration process enabling to perform sensible heating of the ambient air previously dehumidified. Auxiliary unit heaters complete the sensible heat needs of the greenhouse. The same unit heaters are used to perform sensible heating in the traditional greenhouse. Natural ventilation through roof opening is the only method to control the humidity in the traditional greenhouse but it is also used in the innovative one to integrate the desiccant system. The comparative analysis has been carried out for three years from 2010 to 2012 in the winter season, from October the 20th to December the 10th, when the greenhouses are filled with Christmas flowers (Euphorbia Pulcherrima). Three different desiccant solutions have been used in the VLHC system: H_2O-LiCl in 2010, H_2O-KCOOH in 2011 and H_2O-LiBr in 2012. The experimental comparison shows a primary energy saving for the desiccant-based system with respect to the traditional one of 9.6% in 2010, 11.7 % in 2011 and 15.1 % in 2012. In addition, because of the sanitising effect of the desiccant and of a more effective control of the humidity inside the greenhouse, the innovative system ensures a consistent reduction in the use of pesticides with relevant economical and environmental advantages.