Abstract

A windcatcher is a wind-driven natural ventilation system that catches the prevailing wind to bring fresh airflow into the building and remove existing stale air. This technology recently regained attention and is increasingly being employed in buildings for passive ventilation and cooling. The combination of windcatchers and evaporative cooling has the potential to reduce the amount of energy required to ventilate and cool a greenhouse in warm and hot climates. This study examined a greenhouse incorporated with a passive downdraught evaporative cooling windcatcher (PDEC-WC) system using Computational Fluid Dynamics (CFD), validated with experimental data. Different hot ambient conditions of temperature (30–45 °C) and relative humidity (15–45%) were considered. The study explored the influence of different spray heights, layouts, cone angles and mass flow rates on indoor temperature and humidity. The average error between measurements and simulated results was 5.4% for the greenhouse model and 4.6% for the evaporative spray model. Based on the results and set conditions, the system was able to reduce the air temperature by up to 13.3 °C and to increase relative humidity by 54%. The study also assessed the influence of neighbouring structures or other greenhouses that influence the flow distribution at the ventilation openings. The study showed that the windcatcher ventilation system provided higher airflow rates as compared to cross-flow ventilation when other structures surrounded the greenhouse.

Highlights

  • The operations of greenhouses are a significant part of agriculture in many countries

  • The results showed that the proposed system was able to reduce the temperature by up to 14.6 ◦ C

  • The results showed that the windcatcher with cooling devices was able to provide an adequate supply of fresh airflow into the space

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Summary

Introduction

The operations of greenhouses are a significant part of agriculture in many countries. Four and different heights and six massand flow rate and nozzle cone angle on the airflow relative humidity configurations of the evaporative cooling water spray nozzles (three parallel and three staggered) distribution inside the greenhouse. The study assessed the influence of neighbouring structures or other greenhouses

Literature Review
Design Geometry and Configurations
Ambient Conditions and Spray Properties
Mesh and Sensitivity Analysis
Boundary Conditions
Validation of the Greenhouse Model
Validation of the Water Spray System
Impact of Crops on Airflow Characteristics
Impact of Outdoor Air Temperature
Impact
Impact of Outdoor Relative Humidity
Impact of Inlet Nozzle Gauge Pressure
Impact of the Height of Nozzles
Impact of the Layout of Nozzles
4.10. Figure
5.5.Conclusions

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