UPGRADATION OF HVAC SYSTEMS IN EXISTING COMMERCIAL GREEN HOUSE USING EVAPORATIVE COOLERS IN MIDDLE EAST CLIMATIC CONDITIONS

摘要

Commercial green houses are the back bone of farming industry in world where the climatic conditions are not stable especially in Middle East, Europe and United states. The commercial greenhouses are often high tech production facilities for vegetables or flowers. The glass greenhouses are filled with equipment like screening installations, heating, cooling, and lighting and also may be automatically controlled by a computer to maximize potential growth. Greenhouse concept will provide the stable indoor plant growth environment throughout the year irrespective of the outside climate variance. The indoor climate conditions can be maintained using the properly designed HAVC systems. The conventional commercial green houses are equipped with axial fans and the cooling pads to control the indoor climate conditions without central control of the equipment's. Financial conditions of the commercial green houses are very important since the cost per plant will be determined by the overall contribution of the capital and operational expenses. In the present scenario the almost 30% of the net profit is eating by the HVAC systems operational cost. The major operation cost is due to the cooling pads work force and the electricity operational cost for the axial fans equipped with metal blade. The up gradation involves mainly the involvement of individual evaporative air-conditioned system instead of conventional systems. The green houses are equipped with individual evaporative cooling units, circulating fans, top mounted air louvers and the control systems to control the entire set up .The initial heat load calculations will give us an idea about the total heat load required to maintain the ambient conditions for indoor plant cultivation. CFD analysis will provide the exact equipment orientation and the load requirement. In conventional greenhouses the conventional equipment's are equipped to get the results but the same will consume more electrical power and which is not effective in all weather conditions. Heat load calculations will provide us the system demand in a conditioned space based on the available material properties .Based on the heat load results we can do the proper equipment selection and set the airflow based on the demand.CFD analysis will help the modeling of the system in the actual condition. The aim of the study was to analysis the performance study of the individual evaporative cooling units in the greenhouse conditioned space. The results obtained from the heat loads and CFD analysis can be compared. The objective of the present work is to examine the designed Air conditioning system effectiveness in peak summer heat load conditions to check the design parameters (25 °C temperature and 50%RH) inside the greenhouse using Computational Fluid Dynamics (CFD) Analysis.