Closed Greenhouse Heating in an Arid Egyptian Winter Using Earth-Air Heat Exchangers

Abstract

In cold climate regions, closed greenhouses with minimal ventilation minimize the energy requirement for heating compared to open-ventilated greenhouses. In this paper, a model of a closed greenhouse with Earth-Air Heat Exchanger (EAHE) heating is presented and simulations are performed using climate data of a representative day of the coldest month of the year (i.e. January) at the case study location, Hurghada, Egypt. A comparison is made between a closed greenhouse with and without EAHE heating. The simulations show that without heating the greenhouse interior temperature drops below the minimum temperature for cultivation (20°C) during the early and late hours of the day. Furthermore, at midday the temperature inside the greenhouse exceeded the maximum temperature for cultivation (30°C). The results showed that EAHE enabled the greenhouse interior to be maintained at a temperature suitable for plant cultivation, cooling during the day and warming at night. Further, the variability in relative humidity was reduced from 35% to 15%, simplifying the control of the humidity within the greenhouse. Additional simulations that cover the winter period (November to February), demonstrated that the EAHE is a viable sustainable method for temperature regulation without any requirement for additional heating.

Impact of Environmental Factors on Indoor Air Temperature in Gas-Fired Radiant Heated Cultivated Structures

“…Practical horticulture is only feasible when creating favourable temperature and humidity conditions within cultivation structures throughout the entire cold period of the year. To achieve this, various heating systems are employed in winter greenhouses and conservatories, including water (or steam), air, combined water or steam and gas-air systems [9][10][11][12][13][14][15]. The heating of cultivation structures can also be accomplished through the use of electrical energy.…”

“…The heating of cultivation structures can also be accomplished through the use of electrical energy. In addition to the mentioned traditional heating systems, alternative methods for providing thermal comfort to cultivation structures are organized, such as through heat pumps [1,15] or solar collectors (solar greenhouses) [2,6,[10][11][12][13][14]. Currently, for several reasons [3]: artificial source of infrared radiation; the absence of the need for a boiler installation, thermal networks, and related engineering equipment; automation of the technological process; even distribution of thermal energy on the soil surface; possible application of carbon dioxide (CO2) for plant fertilization, obtained from fuel combustion products when using gas infrared emitters -gas radiant heating systems are of significant interest in agriculture [16][17][18][19][20][21][22][23][24][25].…”