Fluid circulation and thermal exchange properties via integrated natural and artificial convection within a container have attracted considerable interest due to its many industrial uses. This present work concentrates on determining the effect of the Richardson number on flow and heat transfer in a cylinder filled with Cu-Water nanofluid at different nanoparticle concentrations. The governing equations: continuity and Navier Stoke fields were discretized using the finite difference approach and simulated in C++ programming language. In this work, the Richardson parameter ranged from 2.6*104 to 2.8*104, while the concentration of Cu nanoparticles ranged from 1% to 10%, and the results are presented as Nusselt number, vorticity, and stream function profiles. The results reveal that the maximum Richardson value is 2.76 x 104 at the nanoparticle volume of 0.04, resulting in a considerable increase in the convective heat transfer rate. Furthermore, as the Richardson parameters increase, the Nusselt number in the nanofluid increases exponentially while the local drag coefficient decreases. The stream function, longitudinal velocity and circulation increase as the Richardson parameters grow. The technical design for air turbulence prediction involves an understanding of the Richardson-driven connection as a mix of wind speed and convective stability variables.

The design of a flat-plate solar collector (FPSC) is accomplished by multiple input multiple output (MIMO) design technique. The design variables (absorber, fluid and glass temperatures; length, width, height of the FPSC) were the unknown variables in the commensurate thermal balance equations based on; component, overall and yardstick thermal balance on the FPSC. Then, simulator matrices were setup comprising of coefficient and column matrices of design functions. The elements of the coefficient matrix were the partial derivatives of the design functions with respect to the design variables. Besides the convective and radiative heat transfer coefficients were function of the design variables. The initial values of the design variables (307K, 334.5K, 368K, 2 m, 1 m, and 0.045m, respectively) were set, at the seventh iteration, the output variables (306.9K, 339.15K, 368.1K, 2.01m, 1.005m, 0.04m, respectively) merged as the design functions → 0 with insignificant change in the design variables. The output results were used to simulate FPSC, to track its responses to changes in the physical conditions, the stimulation revealed some constraints in the design of the FPSC, which is vital information for the overall optimization of the FPSC. The design yardsticks; the thermal efficiency (0.76) and the effectiveness (0.4) are quite pragmatic. This shows that MIMO technique to thermal system design is effective as convergence among the design variables was sought. Moreover, MIMO considered all thermal losses instead of basing the yardsticks on top loss overall transfer coefficient alone; thus, neglecting sidewalls and base losses. Moreover, the advent of connecting box prepares the preheating unit for high temperature drying (> 150 o C) on integration with a reheating unit.

Heat exchange mechanisms involved in the conversion of solar energy to heat were determined using a parabolic trough collector. This study's goal is to examine the impact of operational and environmental factors on the energetic, performance of three different Parabolic Trough Collector receivers used to generate hot water. The collectors used uncoated, grey, and black receiver tubes. The parabolic trough concentrator is built of mild steel as the mainframe support with a segmented mirror reflector. Reflectivity is 0.85, rim angle is 90, an aperture area is 2.42 m2, and concentration ratio is 11.7. The parabolic trough concentrator's focal point has galvanized iron receiving tubes. The receiver tubes were fitted individually via the parabolic reflector's focal point. The thermal exergy of each absorber tube was determined while water flowed at 0.003 kg/s. During the investigation, solar radiation, and water temperatures at the absorber tube's input and outflow were all measured. The results show that both the temperature of the heat transfer fluid and the amount of solar radiation have a substantial effect on thermal energetic performance. This concentrator reduces dependency on electric power while minimizing fossil-fuel emissions, reducing pollution.

Energy demand, global warming from the fossil fuels and attempt to reduce greenhouse gas emission have placed the centre of attention on how to utilize an alternative sources of energy such as renewable energy technology This work presents the design, fabrication, and evaluation of the performance of Parabolic Trough Solar Concentrator (PTSC) as a source of heat energy. The PTSC is built, having the Supporting stand made of mild steel and reflector is made of the segmented mirror having a reflectivity of 0.85, a rim angle of 90 o and aperture area of 2.5 m 2 and with a concentration ratio of 11.7. The receiver pipes are made of three different materials; copper, aluminum, and stainless steel. The effects of shifts in focal lengths on the performance of the PTSC with three different receivers were investigated. The results reveal copper as a receiver tube conducts heat to the heat transfer fluid better than aluminum and stainless steel receivers. The focal length of 30 cm gave the best results compared to other values of 27 and 35 cm with a maximum temperature of 114.4 o C. The experimental results revealed that useful heat gained, overall heat loss coefficient, collector efficiency factor, heat removal factor, collector and thermal efficiency were 147.8 J, 5.04 W/m 2 K, 0.05, 15.05, 0.032% and 15.5% respectively. The study shows that the Parabolic Trough Solar Concentrator as a source of heat energy gives a promising performance. This concentrator will reduce the dependence on the electric power supply, and it controls pollution emanating from fossil fuel, thereby reducing environmental problems. IntroductionThe solar thermal collector is an economical application of solar energy, a clean and environmentally friendly renewable resource. Instead of using electricity, oil, or gas as a source of heat, is an attractive alternative, mainly in places where electric power is not available. Parabolic cylindrical trough collector is one of the solar concentrator technologies for the transformation of solar energy into thermal drive. Blackened metal tube receiver is fitted on the focal plane of the cylinder, and the channel is rotated about its axis to monitor the motion of the sun. The metal tube transporting heat transfer fluid receives heat energy and gets heated. The hot heat transfer fluid is used for other applications. The performance of the trough collector is affected by different parameters such as aperture diameter, rim angle, the reflectivity of the reflector, absorber size, and shape. To enhance the performance of the cylindrical trough collector, researchers all over the world made sincere efforts to optimize the parameters affecting the performance of the system.A tubular cavity receiver with air as heat transfer fluid in a parabolic trough solar concentrator system was analyzed (Bader et al., 2015) and found that the collector efficiency varies between 60 to 65%. Kumaresan et al. (2012) investigated the performance of a solar parabolic trough collector with a thermal energy storage system. The instantaneous...

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