Experimental performance of LPG refrigerant charges with varied concentration of TiO2 nano-lubricants in a domestic refrigerator

This article present an experimental investigation of varied mass charges of Liquefied Petroleum Gas (40 g, 50 g, 60 g and 70 g) enhanced with varied TiO2 nanoparticle/mineral oil concentrations (0.2 g/L, 0.4 g/L and 0.6 g/L nanolubricants) in a R134a compressor of a domestic refrigerator. Performance tests investigated at steady state included: pull down time, power consumption, compressor power input, cooling capacity and coefficient of performance (COP). Analysis was based on temperature and pressure readings obtained from appropriate gauges attached to the test rig. Refrigerant property characteristics were obtained using Ref-Prop NIST 9.0 software. Results obtained showed almost equal evaporator air temperatures and reduction in power consumption for all tested nano-lubricant concentrations except at 70 g charge of LPG using 0.6 g/L nano-lubricant. Furthermore, the lowest compressor power input was found to be 21 W and obtained using 70 g of LPG with either of 0.2 g/L or 0.4 g/L nano-lubricants. At 70 g of LPG using 0.6 g/L concentration of nano-lubricant, highest cooling capacity index of 65 W was obtained while the highest COP of 2.8 was obtained with 40 g charge of LPG using 0.4 g/L concentration of nanolubricant. In conclusion, LPG-TiO2 nano-lubricant mixture works safely and efficiently in domestic refrigerators without modification of capillary tube length, but requires adequate optimization

A framework for selecting the location of very large photovoltaic solar power plants on a global/supergrid

One of the important optimization applications (minimization and maximization) is the power grid systems. National electricity grids should be interconnected to develop larger regional grids (supergrids), and further integrated to build up a worldwide grid (global grid) for minimizing consumption of natural resources and maximizing economical useful life, recycling rate, and effective usage of natural resources. These supergrids and global grid concepts can only be developed through detailed and organized supportive research studies. This research study aims to find, define, identify, describe and select location selection factors of very large photovoltaic solar power plant investments on a global grid and supergrid concepts. Grey systems theory, fuzzy (Type-1 and 2) theories, Mamdani’s type fuzzy rule-based system, Interpretive Structural Modelling (ISM), Impact Matrix Cross-Reference Multiplication Applied to a Classification (MICMAC) tool, and Political, Economic, Social and Technological (PEST) framework and its extensions (SLEPT, PESTEL, PESTLE, STEEPLE, STEEPLED, DESTEP, STEER) are concurrently used in this study. Eleven (11) criteria are presented for preliminary screening (i.e. C1: global horizontal irradiation (GHI), C2: governments supergrid integration policy, C3: supergrid business climate and conditions, C4: High Voltage Direct Current (HVDC) and High Voltage Alternating Current (HVAC) electrification grid infrastructure, C5: land use, allocation and availability, C6: geological conditions, C7: political, war, terror & security, C8: topographical conditions, C9: climatic conditions, C10: water availability conditions, C11: natural disaster/hazard conditions), and 191 factors are presented for pre-feasibility investment stages. Findings can directly be used or taken as a basis for further analysis by researchers and practitioners. Keywords: Fuzzy logic, Global grid, Interpretive structural modelling, MICMAC, PEST, Photovoltaic, Supergri

Experimental performance of LPG refrigerant charges with varied concentration of TiO2 nano-lubricants in a domestic refrigerator

This article present an experimental investigation of varied mass charges of Liquefied Petroleum Gas (40 g, 50 g, 60 g and 70 g) enhanced with varied TiO2 nanoparticle/mineral oil concentrations (0.2 g/L, 0.4 g/L and 0.6 g/L nano-lubricants) in a R134a compressor of a domestic refrigerator. Performance tests investigated at steady state included: pull down time, power consumption, compressor power input, cooling capacity and coefficient of performance (COP). Analysis was based on temperature and pressure readings obtained from appropriate gauges attached to the test rig. Refrigerant property characteristics were obtained using Ref-Prop NIST 9.0 software. Results obtained showed almost equal evaporator air temperatures and reduction in power consumption for all tested nano-lubricant concentrations except at 70 g charge of LPG using 0.6 g/L nano-lubricant. Furthermore, the lowest compressor power input was found to be 21 W and obtained using 70 g of LPG with either of 0.2 g/L or 0.4 g/L nano-lubricants. At 70 g of LPG using 0.6 g/L concentration of nano-lubricant, highest cooling capacity index of 65 W was obtained while the highest COP of 2.8 was obtained with 40 g charge of LPG using 0.4 g/L concentration of nanolubricant. In conclusion, LPG-TiO2 nano-lubricant mixture works safely and efficiently in domestic refrigerators without modification of capillary tube length, but requires adequate optimization

Effect of Oil Bean Stalk Filler on the Thermo-Mechanical Properties of Developed Aluminium Dross Composites for Building Ceilings

Standard quality building material is the demand of this present age. It is a good attempt to draw some ideas about the use of composites in modern building materials. This study experimentally investigates the effect of varying oil beanstalk (OBS) filler and Portland cement (Cmt) additives on thermo-mechanical properties of aluminium dross (Aldr)-Portland cement oil bean-reinforced composites. The specific heat capacity, thermal conductivity, thermal resistivity, thermal diffusivity, thermal effusivity, and compressive strength were determined at a different variation of filler content to investigate its effects on the developed composites' behaviour building ceilings application. Result shows that the physical and mechanical properties of triad 0.6Aldr0.3Cmt0.05G0.05OBS, 0.6Aldr0.32Cmt0.05G0.03OBS composites are better than 0.6Aldr0.34Cmt0.05G0.01OBS composites. Developed samples with Portland cement binders were observed not supporting combustion in the combustion calorimeter, confirming their flame-retardant characteristics. Thermal analysis indicates that reduced additive results in poor thermal performance despite an increment in Portland cement content. The least thermal conductivity value (0.0195 W/m2K) was obtained for sample 2 produced with 60% aluminium dross, 32% Portland cement and 3% oil bean stalk. The developed ceiling materials specific heat capacities increased by 10.33–386.83% compared to asbestos. Compared to Polyvynylchloride (PVC) ceiling material gave a 40.81% reduction in sample 2. The calorific value of oil bean stalk obtained using the combustion calorimeter is 17.80 MJ/kg, lower compared to pulverized coconut shells. It is observed that the best performance of the composite is achieved at moderate Portland cement and filler ratios. A new method of curbing fire spread and providing thermal comfort is essential in this new age of building composite, sustainable cities, and communities; this will come to the fore when inbred exceptional thermal, combustion, and mechanical properties are found in developed building ceilings. The percentage variation of filler on the matrix material necessitates improvement in their behaviour in performance