Abstract
Earth to air heat exchangers are widely utilized to cool or heat passive buildings for energy savings. They often need to deal with high humidity air conditions, especially in the greenhouse due to plant transpiration, and the condensation phenomenon is frequently observed during the cooling process. To evaluate the effect of humidity and condensation on thermal performance, a three dimensional computational fluid dynamic (3D-CFD) model was developed. The distribution of relative humidity in each pipe was investigated, and the impact of inlet air relative humidity on the integrated performance of the earth to air heat exchanger was discussed. The effects of inlet air temperature and volume flow rate were also analyzed. Moreover, the influence of the heat exchanger configurations on the performance of the air condensation was researched. The results indicated that condensation had few effects on the airflow distribution uniformity of the earth to air heat exchanger, while it acted observably on the thermal performance. In addition, humid air in a small diameter pipe tended to condense more easily. Humidity and condensation should be taken into consideration for the design of earth to air heat exchangers in greenhouses during engineering applications.
Highlights
Lekhal et al [8] optimized the parameters of the earth to air heat exchanger (EAHE) in the different climatic regions, and the results showed that there are no standard criteria for all climatic regions
The results showed that latent heat transfer acted significantly on EAHE cooling capacity when the earth to air heat exchanger operated under high temperature and humidity conditions
The relative humidity (RH) non-uniformity in the multi-pipe EAHE is discussed
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Guo et al [16] developed a 3D-CFD model to investigate the cooling performance of the water-sprinkling roof in the greenhouse. The results showed that latent heat transfer acted significantly on EAHE cooling capacity when the earth to air heat exchanger operated under high temperature and humidity conditions. Gao et al [24,25] proposed a new condensation model to simulate the cooling and dehumidification process of buried tunnels, which could obtain the unsaturated condensation process They found that the air humidity acted significantly on the thermo-hygrometric performance of EAHE system. Mongkon et al [29] evaluated the cooling performance and condensation phenomenon of EAHE in the greenhouse They obtained that a small amount of con-. Theimpact impactof structure on on airair condensation in in thethe was studied
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