The thermal performance and environmental impact of agricultural greenhouses (GH) connected to earth-to-air heat exchanger (EAHE) systems depend on the ambient temperature, soil temperature, EAHE system, and greenhouse specifications. The impact of an EAHE system on the temperature and humidity of a GH microclimate, as well as its effects on CO2 emissions and heating energy consumption, are determined experimentally. Two scaled-down models of agricultural GHs (2 × 1.4 × 1.4 m3) were developed. Each GH was equipped with a heater. A spiral EAHE system was integrated into only one of the GHs. The temperature differences in the microclimate range from 3.5 °C to 7.5 °C, with the microclimates of GH + EAHE and GH being quite similar. In summary, the EAHE system helped to reduce the hourly energy consumption of the heating system by more than 40%. It also reduced emissions to the environment by more than 100 g (CO2)/hour. The EAHE coefficient of performance (COP) for the cooling mode has a higher average value than that for the heating mode. The closed-loop performed better in cooling mode, while the open-loop performed better in heating mode. When the difference between the set temperature in the heater and the air outlet temperature of the EAHE system is smaller, the heater performs better in reducing energy consumption and CO2 emissions of the heater. The COPheating range is between 0 and 3.4 and the COPcooling range is between 0.5 and 7.3. The energy consumption ranges between 0 and 1.41 kWh and the CO2 emissions are between 0 and 359.55 g. Thus, using EAHE in agricultural greenhouses improves thermal performance and reduces environmental impact, providing an overall benefit in terms of energy consumption and environmental sustainability.
soil in shallow depths could be used as heat sink / heat source for cooling / heating devices. To predict its thermal behaviour during year, some authors use data from soil temperature records some else use data from average yearly air temperature measurements of meteorologic stations to avoid measure soil temperature in shallow depths for long time. In this research paper, we present a comparison study about the use of soil data and the use of air data for soil temperature prediction, where transient heat conduction in semi-infinite solids is utilised in the study. We measured the soil temperature of three sites for three years in Covilha-Portugal to support the current study. Later, we create reference years of soil temperature in the three sites.
Appropriate measures have been taken to reduce energy requirements for cold chain applications. Thermal energy storage is an accepted method to reduce the need for electrical energy after harvesting fresh horticultural produce. The use of phase change materials (PCM) in postharvest storage, outside of a temperature-controlled environment, extends shelf life and keeps food at the ideal temperature. This review focuses on the various trials using PCM to improve cold chain effectiveness. It also discusses the advantages and disadvantages of each type of storage using different PCM, as well as the likely and potentially promising applications of thermal energy storage in the cold chain.
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