3 research outputs found
Properties of Earth-to-Air Heat Exchangers (EAHE): Insights and Perspectives Based on System Performance
No full textEarth–Air Heat Exchange (EAHE) systems are an eco-friendly and energy-efficient technology as pre-heating or pre-cooling systems in civil buildings. Technically, the performance of the EAHE system is influenced by properties associated with the technology. In this paper, the focus is placed on the properties covered by the published literature to understand how they impact the efficiency of these systems. The review scrutinizes the implication of pipe properties such as the material type (steel, Polyvinyl Chloride [PVC], concrete, or high-density polyethylene), diameter and length, and depth in the context of modern building design and energy conservation. Other properties considered in this work are air velocity and the bonding of pipes with the soil. The EAHE systems’ performance is not significantly influenced by the pipe material, unlike the pipe length and diameter. It is reported that longer pipes enhance the cooling output in the EAHE system. The pipe length positively correlates with the in-pipe air temperature. An increment in the pipe diameter led to a drop in the in-pipe air temperature. An indicative report states that an increasing air flow velocity can lead to thermal losses from pipes to their surrounding soil. The addition of sand below and above the pipe enhances the thermal conductivity, just as an increase in the moisture content of the soil will contribute. There are attempts to use additives, construction waste, graphite, and fly ash as a backfill material, but with opposing economic feasibility. Construction waste could help the EAHE system to improve by 80%. A combination of graphite and fly ash as a backfill material is cost-effective. Research on the pipe material type and standards development are limited. Overall, the pipe material type and length to adopt for an EAHE system are based on the funds’ availability for the construction
Characterization of Chemically Synthesized Transition Metal Sulfides (MnS) Thin Films via Pneumatic Spray Technique.
No full textThis work studies the structure of manganese sulfide thin film on a glass substrate at 250°C using the pneumatic spray technique with a concentration of 0.15 mol. X-ray analysis showed that the MnS thin film has a hexagonal phase of γ-MnS and a cubic phase of α-MnS. The average crystallite size was found using the Debye-Scherrer equation and the Williamson-Hall plot to be 12.88 nm and 10.01 nm, respectively. Structural characterization using SEM revealed that the surface of the MnS thin film is regular and homogeneous, containing small spherical grains approximately 135.3 nm in size. EDAX analysis confirmed that the film contains manganese (Mn) and sulfur (S) without any impurities. The 2D and 3D AFM images of the MnS thin film revealed intergranular interactions, and the surface roughness was calculated to be 46.7 nm. Optical measurements showed high transmittance of up to 67%, and the optical band gap and Urbach energy were calculated to be 2.87 eV and 0.38 eV, respectivelyThe presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
