Articles
Greenhouse dehumidification by an air-air heat pump under Mediterranean conditions
Article number
1296_25
Pages
193 – 202
Language
English
Abstract
The greenhouse dehumidification by an air-to-air heat pump and heat pump efficiency under middle weather conditions were evaluated in this study.
Dehumidification in a closed tunnel greenhouse was achieved by the aforementioned pump when the air relative humidity was above 80% as cucumber plants were cultivated in the soil (a second tunnel greenhouse was used as a control). Greenhouse air was dehumidifying as it was forced to pass firstly through the heat pump evaporator by a fan, where it was being cooled and left some of its moisture on the evaporator, and then through the condenser, where it was being heated and eventually returned to the greenhouse.
Water vapour losses were estimated for both greenhouses.
Heat pump operating parameters such as dehumidified coefficient of performance (COPdeh), thermal coefficient of performance (COPheat), specific energy consumption (SEC), depending on operating conditions and operating frequency were determined.
COPdeh was increased accordingly to greenhouse air temperature.
Based on Athens’ climatic conditions, to maintain the relative humidity of the greenhouse air at 80%, the maximum required heat pump power was estimated at 12.3 W m‑2, while the specific energy consumption ranged from 0.4 to 0.8 kWh kg‑1. Greenhouse dehumidification by the heat pump increased the air temperature up to 2°C and the crop evapotranspiration (up to 73%) compared to the control greenhouse as well as caused a severe reduction in water vapour condensation in the internal surface of the greenhouse cover.
Consequently, greenhouse dehumidification by an air-air heat pump is an effective method especially under middle weather conditions where water vapour losses through condensation on the cover and through infiltration are relatively low.
Dehumidification in a closed tunnel greenhouse was achieved by the aforementioned pump when the air relative humidity was above 80% as cucumber plants were cultivated in the soil (a second tunnel greenhouse was used as a control). Greenhouse air was dehumidifying as it was forced to pass firstly through the heat pump evaporator by a fan, where it was being cooled and left some of its moisture on the evaporator, and then through the condenser, where it was being heated and eventually returned to the greenhouse.
Water vapour losses were estimated for both greenhouses.
Heat pump operating parameters such as dehumidified coefficient of performance (COPdeh), thermal coefficient of performance (COPheat), specific energy consumption (SEC), depending on operating conditions and operating frequency were determined.
COPdeh was increased accordingly to greenhouse air temperature.
Based on Athens’ climatic conditions, to maintain the relative humidity of the greenhouse air at 80%, the maximum required heat pump power was estimated at 12.3 W m‑2, while the specific energy consumption ranged from 0.4 to 0.8 kWh kg‑1. Greenhouse dehumidification by the heat pump increased the air temperature up to 2°C and the crop evapotranspiration (up to 73%) compared to the control greenhouse as well as caused a severe reduction in water vapour condensation in the internal surface of the greenhouse cover.
Consequently, greenhouse dehumidification by an air-air heat pump is an effective method especially under middle weather conditions where water vapour losses through condensation on the cover and through infiltration are relatively low.
Publication
Authors
I. Lycoskoufis, G. Lambrinos, G. Mavrogianopoulos
Keywords
moisture, condensation, evapotranspiration, infiltration, relative humidity
Groups involved
- Division Precision Horticulture and Engineering
- Division Greenhouse and Indoor Production Horticulture
- Working Group Organic Greenhouse Horticulture
- Working Group Protected Cultivation, Nettings and Screens for Mild Climates
- Working Group Light in Horticulture
- Working Group Vegetable Grafting
- Working Group Computational Fluid Dynamics in Agriculture
- Working Group Mechanization, Digitization, Sensing and Robotics
- Working Group Modelling Plant Growth, Environmental Control, Greenhouse Environment
- Working Group Greenhouse Environment and Climate Control
- Working Group Design and Automation in Integrated Indoor Production Systems
- Commission Agroecology and Organic Farming Systems
- Division Landscape and Urban Horticulture
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