The performance of Solar Air heaters can be enhanced by placing ribs of different geometries over the absorber plate which increases turbulence and thereby increasing its heat transfer and friction factor characteristics. It has been reported by various researchers that Double pass solar air heaters are more efficient than single pass solar air heaters in terms of its Thermal performance. It is also reported that using discrete ribs over the absorber plate in place of continuous ribs gives more heat transfer. The present paper gives us the details of various artificial roughness provided over the absorber plate to increase turbulence. This paper gives a brief overview of various researches done on Single as well as Double pass solar air heaters in terms of its Thermal and Thermohydraulic efficiencies along with Nusselt Number and Friction Factor enhancement.

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The current study aimed to measure the status of water quality of Chenab River, Neeru Stream and Bischleri Stream. Samples of water were collected from twenty different locations in the month of June, 2022. The focus of the study was to check pollution load and heavy metal contamination using various water quality indices. As per BIS and WHO standards, it was found that maximum parameters were within the permissible limit except pH, turbidity, Calcium (Ca) and Magnesium (Mg) at some sampling points. The results reveal that the quality of water in the studied area was good as seen from Water Quality Index (WQI) values which were found between 34.8 to 44.8. The Comprehensive Pollution Index (CPI) value ranges from medium to heavy pollution in maximum sampling points due to increased concentration of Chromium (Cr) in water samples. HPI index value found above the critical limit (>100) showed pollution load in the water. The river water was found to deteriorate due to the influence of wastewater discharge into the river directly or other anthropogenic activities.