Energies, Vol. 19, Pages 875: Experimental Investigation of Wall Confluent Jets on Transparent Large-Space Building Envelopes: Part 2—Application in Cooling Greenhouses

Energies doi: 10.3390/en19040875

Authors:
Gasper Choonya
Alan Kabanshi
Bahram Moshfegh

This study experimentally evaluated the performance of a wall confluent jet (WCJ) cooling system in a greenhouse under real summer and autumn weather conditions. It examined the effects of indoor air temperature setpoint (Tspt), number of nozzle rows (n) on the WCJ diffuser, and external wall shading on WCJ’s cooling performance. Thermocouples and constant-current anemometers measured air and surface temperatures and air velocity, while pyranometers measured solar radiation. The WCJ system dynamically regulated inlet air temperature between 14 °C and 25 °C to counter solar and conductive heat gains, maintaining indoor air temperature within ±1.5 °C of the setpoint. Increasing Tspt by 4 °C reduced inlet cooling demand by 25% but increased indoor air temperature by 20–25% and raised ceiling, wall, and floor surface temperatures by 17%, 20%, and 16%, respectively. Increasing n reduced surface temperatures by up to 8% and indoor air temperature by 6%. External wall shading reduced solar heat gain, lowering interior surface temperatures by 10–30%, peak and mean indoor air temperatures by up to 35% and 15%, and net power peaks by 40%. Autumn conditions reduced cooling loads by 50% relative to summer. Overall, WCJ cooling demonstrates strong potential as an alternative or complementary system for greenhouse thermal regulation without increasing primary energy demand.

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Gasper Choonya www.mdpi.com