This paper presents the effects of saturation temperature and inclination angle on convective heat transfer during condensation of R134a in an inclined smooth tube of inner diameter of 8.38 mm.Experiments were conducted for inclination angles ranging from -90° (vertical downwards) to

An experimental study of the pressure drops during the condensation of R134a in a smooth copper tube of inner diameter of 8.38 mm was carried out for vapour qualities ranging between 0.1 and 0.9, mass fluxes between 100 kg/m 2 s and 400 kg/m 2 s, and saturation temperatures between 30°C and 50°C. Inclination angles ranging from-90° (downward flow) to +90° (upward flow) were considered. The pressure drop was measured directly by means of calibrated differential pressure transducers connected to the inlet and the outlet of the test condenser. It was found that the pressure drop is significantly influenced by the inclination angle and saturation temperature. The void fraction and frictional pressure drop results also show that they are largely influenced by these parameters. While the highest and lowest measured pressure drops were obtained during the upward flow and downward flow respectively, the results obtained for the void fraction and the frictional pressure drop showed that the highest values were obtained during the downward flow while the lowest values were obtained during the horizontal and upward flows.

solar collectors, evaporators, condensers and relevant energy storage schemes during thermal charging and discharging. A brief overview of some energy storage options are also presented to motivate the inclusion of thermal energy storage into direct steam generation systems.

Solar dryers are imperative for the tropical and sub-Saharan African countries, which are faced with the duo challenges of inadequate electrical energy supply, which has severely limited the application of conventional refrigeration as a means of preservation of agricultural produce, and the need to make produce competitive in the international market. In this study, a cost-effective natural convection solar dryer was developed; the thermal and drying analyses were done and tested to obtain some performance evaluation parameters for the system in order to examine its efficiency and effectiveness by drying some plantain fillets. The collector and system efficiencies are found to be 46.4% and 78.73%, respectively, while a percentage moisture removal of 77.5% was achieved at the 20th hour in order to give final moisture contents of 15.75% in the product, which still maintained its integrity. With a cost of about $195.00, it has been affordable for the small- and medium-scale enterprises as well as for private use in domestic applications.

In this study, the heat transfer characteristics of a new class of nanofluids made from mango bark was numerically simulated and studied during turbulent flow through a double pipe heat exchanger. A range of volume fractions was considered for a particle size of 100 nm. A two-phase flow was considered using the mixture model. The mixture model governing equations of continuity, momentum, energy and volume fraction were solved using the finite-volume method. The results showed an increase of the Nusselt number by 68% for a Reynolds number of 5,000 and 45% for a Reynolds number of 13 000, and the heat transfer coefficient of the nanofluid was about twice that of the base fluid. In addition, the Nusselt number decreased by an average value of 0.76 with an increase of volume fraction by 1%. It was also found that there was a range of Reynolds numbers in which the trend of the average heat transfer coefficient of the nanofluid was completely reversed, and several plots showing zones of higher heat transfer which if taken advantage of in design will lead to higher heat transfer while avoiding other zones that have low heat transfer. It is hoped that these results will influence the thermal design of new heat exchangers.