Sun drying of cocoa with firebrick thermal storage materials

The thin-layer drying process of N38 cocoa beans using open-sun and a solar drying (SD) system with firebrick heat storage materials (FTSM) has been modeled. The 10 kg capacity force convective SD system was developed and used to carry out the experiments. The choice of the best model was based on a comparison of statistical indicators including determination coefficient (R²), reduced chi-square (χ²), root mean square error (RMSE), sum of square error (SSE), and normalized root mean square error (NRMSE) after fitting the experimental results to 11 common thin layer models in the literature. The results revealed that under open-sun drying and SD processes, the Midilli et al model provided the best drying characteristics of cocoa beans. Therefore, in the experimental context, this model can be assumed to reflect the solar/sun drying behavior of cocoa. The effective diffusivity values for the open-sun and SD of cocoa with FTSMA and FTSMB were 4.25× 10⁻¹¹, 6.64× 10⁻¹¹, and 5. 95 × 10⁻¹¹ m²/s respectively. The predicted pre-exponential factor and activation energy were 5.81 × 10⁻¹¹ m²/s and 22.79 kJ/mol respectively.     

Greener energy: Issues and challenges for Pakistan—Solar energy prospective

Energy plays a pivotal role in socio-economic development by raising standard of living. It is becoming gradually accepted that current energy systems, networks encompassing every thing from primary energy sources to final energy services, are becoming unsustainable. Development of conventional forms of energy for meeting the growing energy needs of society at a reasonable cost is the responsibility of the Governments. In recent years, public and political sensitivities to environmental issues and energy security have led to the promotion of renewable energy resources. Diversification of fuel sources is imperative to address these issues; and limited fossil resources and environmental problems associated with them have emphasized the need for new sustainable energy supply options that use renewable energies. Development and promotion of new non-conventional, alternate and renewable sources of energy such as solar, wind and bio-energy, etc. are now getting sustained attention. Solar power is one of the hottest areas in energy investment right now, but there is much debate about the future of solar technology and solar energy markets. This investigates the progress and challenges for solar power in Pakistan according to the overall concept of sustainable development, and identifies the region wise potential of solar power in Pakistan and its current status. Barriers are examined over the whole solar energy spectrum and policy issues and institutional roles and responsibilities are discussed.     

Mixed convective heat transfer in rectangular enclosures driven by a continuously moving horizontal plate

The fluid flow and heat transfer induced by the combined effects of the mechanically driven lid and the buoyancy force within rectangular enclosures were investigated in this work. The fluid filled enclosures are heated and lid-driven either on the upper or on the lower horizontal wall, thermally isolated on the right vertical wall, and cooled on the other walls. The basis of the investigation was the numerical solutions of the equations for the conservation of mass, momentum, and energy transport using the finite difference method. The effects of the flow governing parameters including the Richardson and the Prandtl numbers, and the length-to-height aspect ratio, respectively, in the range 10⁻²  Ri  10², 10⁻³  Pr  10, and 1  AR  4 for a fixed Reynolds number, Re = 100, were studied. The results are presented in the form of the hydrodynamic and thermal fields, and the profiles for vertical and horizontal components of velocity, temperature, and the local heat flux. The fluid flow and energy distributions within the enclosures and heat flux on the heated wall are enhanced by the increase in the Richardson number. While an increase in the Prandtl number improves the heat flux on the heated wall, an increase in aspect ratio suppresses it. The results can be used as base line data in the design of systems in which mixed convection heat transfer in rectangular enclosures occurs.     

High Efficiency Neutron Detector for Low Neutron Flux Measurement

A neutron flux detector composed of a bank of nine He³ detectors is developed. It is employed successfully to record neutron flux from a pulsed source as low as 5 × 10² neutrons per m², which is about 0.5 nrem per shot. It may find applications in recording low neutron flux at large distances from the source or in detecting leakage from the radiation shield, and hence may help to estimate health hazards.     

Single and two-phase flow modeling and analysis of a coaxial vacuum tube solar collector

In this paper, an analytical steady state model is developed to study the thermal performance of an individual vacuum tube solar collector with coaxial piping (direct flow type) incorporating both single and two-phase flows. A system of equations which describe the different heat transfer mechanisms and flow conditions was established, discretised, and solved in an iterative manner. For the case of good vacuum condition (10^?5 mb) the calculated efficiency curve for single phase flow deviates significantly from the experiments with increasing collector temperature, but agrees well for the case of gas conduction inside the glass envelope at very low pressure (?1 mb) due to the corresponding increase in overall heat loss coefficient (U-value).For two-phase flow, the occurrence and propagation of flow boiling and condensation inside the collector piping under saturated condition is hypothesized. The modeling results indicate that for all-liquid-single-phase fluid flow, the collector efficiency decreases with decreasing mass flow rate. Once the fluid reaches the boiling point at a certain mass flow rate, no significant reduction in efficiency is observed anymore, which is in accordance with the experimental study.     

Semi-modified okara whey diet increased insulin secretion in diabetic rats fed a basal or high fat diet

Food Science and Biotechnology - Lifestyle and diet preferences are primarily responsible for developing type 2 diabetes. In this study, okara was manufactured into okara whey crackers (OWC) to...     

Bayesian belief-based model for reliability improvement of the digital reactor protection system

Nuclear Science and Techniques - This paper introduces some latest developments regarding the X-ray imaging methodology and applications of the X-ray imaging and biomedical application beamline...