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Summary: Li‐ion batteries (LIBs) are being used extensively in a wide range of applications owing to the facile preparation technology as well as a high energy density, which exceeds those of other commercial batteries. However, LIBs alone cannot satisfy the burgeoning energy demand due to Li‐resource constraints. Recently, K‐ion batteries (KIBs) have garnered the interest of the scientific community as promising alternatives for LIBs due to the abundance of K resources, the affordability of K, and its superior electrochemical properties. However, the development of KIBs is hindered by the slow development of appropriate anode materials that can accommodate the repeated intercalation/deintercalation of large K ions without sustaining significant structural damage. Thus, the development of appropriate anode materials is crucial for the realization of practically viable KIBs. Carbon nanomaterials are promising anode materials due to their remarkable potassiation/depotassiation ability, structural stability, and structural evolution from zero to three dimensions. It is anticipated that an evaluation of the recent advances in carbon and their composites anode materials for KIBs can facilitate the development of practically viable KIBs. This review comprehensively discusses recent developments in carbonaceous and their composites as anode materials for KIBs and provides a prospective for the next research step. [ABSTRACT FROM AUTHOR]

A widely used hydrochlorofluorocarbon (HCFC) refrigerant HCFC‐22 in the split air conditioner (AC) is being phased out in all countries under the Montreal Protocol. Propane (HC‐290) is a favorable substitute for HCFC‐22. The performance, environment impact and cost‐benefit analysis of a split AC unit operated with HCFC‐22 and HC‐290 has been carried out experimentally under different test conditions prescribed by IS 1391. The results showed that the variation in system performance was more significant for HCFC‐22 than for that of HC‐290 while varying the refrigerant charge. The experienced optimum charges that represent the maximum coefficient of performance (COP) was varied with the working environment and it was realized that, generally the optimum charge for HC‐290 was 50% lesser than that of HCFC‐22. The COP of the AC unit with HC‐290 was observed to be 5% more than that of HCFC‐22. However, the system capacity diminished by 7.8%. The operation of a split AC unit with HC‐290 produced up to 15.9% lesser CO2 emission than that of HCFC‐22 under all the test conditions. The use of HC‐290 in an existing HCFC‐22 split AC system can save up to 12.22% of the life time total cost. Finally, it was inferred that the replacement of HCFC‐22 with HC‐290 in the split AC unit showed dominance in all aspects such as performance, emission, and life time total cost. [ABSTRACT FROM AUTHOR]