In this study, a new approach for numerically modeling of an entire cabinet solar dryer is proposed. Collector, drying chamber and chimney are the three principle sections considered in the present modeling. The collector section containing a cover and an absorber plate is modeled applying energy and fluid flow equations to obtain temperature distribution inside the collector. Due to the non-linear behavior of the governing equations as well as variety of effective variables, an iterative method is employed for solution. Regarding the geometry complexity of the drying chamber along with the air compressibility (that in turn causes coupling of momentum and energy equations) drying chamber is simulated by CFD method. Chimney’s effect and effective parameters in suction are comprehensively considered in the present model. The numerical results are in line with experimental results which show that the model can be applied with certainty to employ the dryer for drying highly demanded and time-consuming products in a scientific, sanitary, and timely manner. The model is then optimized by adding some baffles to achieve higher efficiencies and accelerate the drying process.

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The hybrid solar chimneys power plant can produce electric energy and fresh water simultaneously. The purpose of this research is to numerically analyze the hybrid solar power plant, using heat transfer mathematical models. In this study, performance of two different cases for power generation is investigated. First, combination of solar chimney and humidifier is investigated, and second, combination of the solar chimney, humidifier, and a condenser is investigated. The effect of solar radiation and water temperature used in the humidifier on the produced electric power and fresh water is investigated. Obtained results of the first case show that adding moisture in the collector entry, it can decrease air weight as much as the radiation of the sun. According to the results obtained, in the integrating solar chimney with the humidifier, generated power increases by higher solar radiation in all three modes, although the increased power of the first case with spraying water of 40, 20, and 10°C is almost 4 times, 2.7 times, and 1.3 times higher in comparison with the classical solar chimney. It is found for the second case that, for increased solar radiation in the above three cases, the humidifier output air temperature increases and the amount of produced water and relative humidity at the output of the humidifier decreases.

Advanced combined cycles using gas turbine and bottoming cycles have been developed to improve energy efficiency and output power of the conventional thermal power plants. In this study, integrated biomass gasification‐cascaded humidification advanced turbine and steam turbine cycle have been presented as a novel approach to reach out the sustainable energy vision. All generators of this comprehensive system operate by syngas produced from biomass gasification. Based on the technical consideration, modeling and simulation of the mentioned cycle have been performed, which results indicated more than 33.6 MW power generation and about 56.4% total efficiency in the base case. Moreover, parametric studies demonstrated the considerable dependency of the delivered power, specific fuel consumption, and heat rate to ambient temperature variations. In addition, principal parameters changes due to the fluctuation of the gasification temperature demonstrated an obvious increase in fuel consumption rate after crossing a turning point. Eventually, other achievements such as the negative effect of biomass moisture increase on cycle outputs, and also, advantages of turbine inlet temperature rise have obtained by plant analyzes. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019

Efficiently employing two-phase flows for cooling objectives requires comprehensive knowledge of their behavior in different conditions. Models, capable of predicting heat transfer and fluid flow trends in this area, are of great value. Numerical/analytical models in the literature are one-dimensional models involving with many simplifying assumptions. These assumptions in most cases include neglecting some mechanisms of mass transfer in two-phase flows. This study is devoted to developing an analytical two-dimensional model for simulation of fluid flow and mass transfer in two-phase flows considering the all mass transfer mechanisms (entrainment, evaporation, deposition and condensation). The correlation employed for modeling entrainment in this study, is a semiempirical correlation derived based on physical concept of entrainment phenomenon. Emphasis is put on the annular flow pattern of liquid vapor two-phase flow since this regime is the last encountered two-phase regime and has a higher heat transfer coefficient among other two-phase flow patterns. Attempts are made to employ the least possible simplification assumptions and empirical correlations in the modeling procedure. The model is then verified with experimental models of Shanawany et al., Stevanovic et al. and analytical model of Qu and Mudawar. It will be shown, considering pressure variations in both radial and axial directions along with applying our semiempirical entrainment correlation has improved the present analytical model accuracy in comparison with the accuracy of available analytical models.