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- Aacharya, Ananta, et al.
(författare)
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Development of a novel solar dryer with an incorporated heat exchanger
- 2024
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Ingår i: Solar Energy. - 0038-092X. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- This study analyzes the thermal performance of an indirect-type solar dryer incorporated with a heat exchanger to recover heat from the exhaust. Data were recorded for 8 h from 9:00 to 17:00 from November to January to determine the drying rate for varying airflows from 2 l/s to 12 l/s under the weather conditions of Nepal and Bhutan. The air temperatures in multiple locations in the dryer were recorded and logged for 30-second intervals. The results indicated that incorporating a simple heat exchanger can achieve 78 % and 81 % effectiveness for the lowest tested airflow of 2.5 l/s and 2 l/s in Nepal and Bhutan. The heat transfer effectiveness increases with decreasing flow, resulting in a higher cold side outlet temperature of the heat exchanger for lower airflows. The solar air collector demonstrated efficient performance, achieving 80 % and 90 % efficiencies for the highest tested airflows of 12 l/s and 10 l/s in Nepal and Bhutan, respectively. Due to an increased heat transfer coefficient, the incoming air can effectively remove the accumulated heat from the absorber plate for higher airflows. The drying rates were observed to be the highest for 12 l/s, with a value of 85 g/(h × m2) for apples and 10 l/s, with a value of 56 g/(h × m2) for gingers in Nepal and Bhutan, respectively. From both cases, it can be concluded that the highest tested airflows provide higher air circulation for effective heat and mass transfer from the product to the surrounding air for drying.
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| 2. |
- Chaulagain, Nischal, et al.
(författare)
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Airtightness of Nepalese Residential Buildings
- 2022
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Ingår i: Periodica Polytechnica Architecture. - 1789-3437. ; 53:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Experimental field measurements regarding airtightness following the fan pressurisation method were done on 25 typical residential buildings at different locations in Nepal. The field measurement data were classified according to building type and building age.The mean air permeability (Q50 ) for the studied buildings was 6.9 l/s·m2 and the mean air change rate was 55.5 air changes per hour at 50 Pa. The maximum air leakage rate (Q50 ) was 28.4 l/s·m2 for brick masonry in mud mortar type and the minimum recorded was 1.7 l/s·m2 for brick masonry in cement mortar type building. Brick masonry in mud mortar-type buildings was found to be leakier regardless of the building age, and brick masonry in cement mortar-type buildings was comparatively more airtight. Leakage locations identified through visual inspection included the spacing between the door frame and operable door area, horizontal window slider, joint areas of window frame and wall, wood plank-based wall structure, roof joint areas and holes in the wall. This research is the first of its kind in Nepal to assess the airtightness of buildings, and the outcome of this research is one of the key parameters to evaluate the thermal performance of Nepalese buildings scientifically.
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