An exergetic optimization is developed to determine the optimal performance and design parameters of a solar photovoltaic (PV) array. A detailed energy and exergy analysis is carried out to evaluate the electrical performance, exergy destruction components, and exergy efficiency of a typical PV array. The exergy efficiency of a PV array obtained in this paper is a function of climatic, operating, and design parameters such as ambient temperature, solar radiation intensity, PV array temperature, overall heat loss coefficient, open-circuit voltage, short-circuit current, maximum power point voltage, maximum power point current, and PV array area. A computer simulation program is also developed to estimate the electrical and operating parameters of a PV array. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, exergetic optimization has been carried out under given climatic, operating, and design parameters. The optimized values of the PV array temperature, the PV array area, and the maximum exergy efficiency have been found. Parametric studies have been also carried out.

Faramarz Sarhaddi

Said Farahat

Hossein Ajam

Amin Behzadmehr

Exergetic Optimization of a Solar Photovoltaic Array

Optical fiber thermometry technology for high-temperature measurement is briefly reviewed in this paper. The principles, characteristics, recent progresses and advantages of the technology are described. Examples of using the technology are introduced. Many blackbody, infrared, and fluorescence optical thermometers are developed for practical applications.

Y. B. Yu

W. K. Chow

Review on an Advanced High-Temperature Measurement Technology: The Optical Fiber Thermometry

The first and second laws of thermodynamic were applied to statistical databases on nutrition and human growth in order to estimate the entropy generation over the human lifespan. The calculations were performed for the cases of variation in the diet composition and calorie restriction diets; and results were compared to a base case in which lifespan entropy generation was found to be 11&#x2009;404 kJ/K per kg of body mass, predicting a lifespan of 73.78 and 81.61 years for the average male and female individuals respectively. From the analysis of the results, it was found that changes of diet &#37;  of fat and carbohydrates do not have a significant impact on predicted lifespan, while the diet &#37;  of proteins has an important effect. Reduction of diet protein &#37;  to the minimum recommended in nutrition literature yields an average increase of 3.3 years on the predicted lifespan. Changes in the calorie content of the diet also have an important effect, yielding a &#37;  increase in lifespan equal or higher than the &#37;  reduction in the diet caloric content. This correlates well experimental data on small mammal and insects, in which lifespan has been increased by diet restriction.

Carlos A. Silva

Kalyan Annamalai

Entropy Generation and Human Aging: Lifespan Entropy and Effect of Diet Composition and 
 Caloric Restriction Diets

 In this communication, we review recent studies by these authors for modeling the <svg style="vertical-align:-3.27548pt;width:24.299999px;" id="M1" height="14.4125" version="1.1" viewBox="0 0 24.299999 14.4125" width="24.299999"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,14.4125)">
		<g transform="translate(72,-60.47)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝐿</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-63.1,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑊</tspan>
			</text>

		</g>
	</g>
</svg>-<i  >H</i>
                         equilibrium. With the aim of estimating the solubility of pure hydrocarbon hydrate former in pure water in equilibrium with gas hydrates, a thermodynamic model is introduced based on equality of water fugacity in the liquid water and hydrate phases. The solid solution theory of Van der Waals-Platteeuw is employed for calculating the fugacity of water in the hydrate phase. The Henry's law approach and the activity coefficient method are used to 
                        calculate the fugacities of the hydrocarbon hydrate former and water in the liquid water phase, respectively. The results of this model are successfully compared with some selected experimental data from the literature. A mathematical model based on feed-forward artificial neural network algorithm is then introduced to estimate the solubility of pure hydrocarbon hydrate former in pure water being in equilibrium with gas hydrates. Independent experimental data (not employed in training and testing steps) are used to examine the reliability of this algorithm successfully.

Amir H. Mohammadi

Dominique Richon

Development of Predictive Techniques for Estimating Liquid Water-Hydrate Equilibrium of Water-Hydrocarbon System

A numerical study of the effect of slip flow irreversibility and axial conduction in microdevices with a conjugate heat transfer between unmixed streams is presented. The effects of axial conduction due to parallel flows for thermal management in energy systems are investigated. Silicon substrate containing rectangular microchannels is simulated using a finite volume, staggered coupling of the pressure-velocity fields. The entropy generation transport within the entire system is analyzed and coupled with the solution procedure. The effects of channel size perturbation, Reynolds number, and pressure ratios on the thermal performance and exergy destruction are presented. Comparative analysis of the axial conduction and flow irreversibility between parallel flow on thermal management is studied. A proton exchange membrane (PEM) fuel cell model is used as a quality indicator to access the importance of the exergy-based design method.

E. O. B. Ogedengbe

Thermal Management with Solid-Fluid Slip Irreversibility Treatment in Conjugate Microdevices

The aim of this paper is to analyse the natural convective heat transfer generated by a source with a height of <svg style="vertical-align:-2.29482pt;width:8.4875002px;" id="M1" height="13.425" version="1.1" viewBox="0 0 8.4875002 13.425" width="8.4875002"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,13.425)">
		<g transform="translate(72,-61.26)">
			<text transform="matrix(1,0,0,-1,-71.95,63.6)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝜁</tspan>
			</text>

		</g>
	</g>
</svg> located in two different positions inside a square enclosure of side <svg style="vertical-align:-0.0pt;width:15.175px;" id="M2" height="10.325" version="1.1" viewBox="0 0 15.175 10.325" width="15.175"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,10.325)">
		<g transform="translate(72,-63.74)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝐻</tspan>
			</text>

		</g>
	</g>
</svg>. In the first case, <svg style="vertical-align:-0.13794pt;width:7.9875002px;" id="M3" height="10.7375" version="1.1" viewBox="0 0 7.9875002 10.7375" width="7.9875002"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,10.7375)">
		<g transform="translate(72,-63.41)">
			<text transform="matrix(1,0,0,-1,-71.95,63.6)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝛿</tspan>
			</text>

		</g>
	</g>
</svg> is 0.5 of <svg style="vertical-align:-0.0pt;width:15.175px;" id="M4" height="10.325" version="1.1" viewBox="0 0 15.175 10.325" width="15.175"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,10.325)">
		<g transform="translate(72,-63.74)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝐻</tspan>
			</text>

		</g>
	</g>
</svg> while in the second case it is 0.4. The comparison is based both on the evaluation of the local and average Nusselt numbers at different Rayleigh numbers and on the study of the velocity fields at the same Rayleigh numbers in the two different configurations. The experimental analysis was carried out through a holographic interferometry, to study the heat transfer, and through a 2D-PIV system, to analyse the dynamic behaviour of the phenomenon. Finally, for  <svg style="vertical-align:-0.13794pt;width:7.9875002px;" id="M5" height="10.7375" version="1.1" viewBox="0 0 7.9875002 10.7375" width="7.9875002"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,10.7375)">
		<g transform="translate(72,-63.41)">
			<text transform="matrix(1,0,0,-1,-71.95,63.6)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝛿</tspan>
			</text>

		</g>
	</g>
</svg> = 0.5 we compared the experimental results with those obtained through the volume finite software Fluent 6.3.26. In the analysis, it is possible to see that the position of the source influences both the average Nusselt numbers on the hot surfaces and the development of a small bubble on the upper surface.

Francesco Corvaro

Massimo Paroncini

The Natural Convective Heat Transfer in a Partially Divided Enclosure: A Study on the Influence of the Source Position

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Journal of Thermodynamics