Erdem Cuce

Improving thermodynamic performance parameters of silicon photovoltaic cells via air cooling

A numerical and experimental study based on analysing the cooling effect on performance characteristics of silicon solar cells is presented. In the experiments carried out for different cell temperatures, a substantial decrease in power output with increasing cell temperature was observed depending on the decrease in exergy efficiency. In contrast to the remarkable decrease in voltage parameters, a slight increase in current parameters with increasing cell temperature was obtained. A well-known computational fluid dynamics software was utilised to evaluate the effectiveness of cooling applications in terms of enhancement of energy conversion in silicon solar cells. Air was chosen as the cooling fluid in the numerical study. The numerical study was performed for various velocities and temperatures of cooling fluid. Enhancement in energy conversion was determined for each operating condition. The results indicated that cooling applications are quite important to improve the efficiency and the maximum power output of the photovoltaic modules. These strategies can be more efficient for large-scale photovoltaic power plants.

Homotopy perturbation method for temperature distribution, fin efficiency and fin effectiveness of convective straight fins with temperature-dependent thermal conductivity

Homotopy perturbation method is a novel approach that provides an approximate analytical solution to differential equations in the form of an infinite power series. In our previous work, homotopy perturbation method has been used to evaluate thermal performance of straight fins with constant thermal conductivity. A dimensionless analytical expression has been developed for fin effectiveness. In this study, homotopy perturbation method has been applied to convective straight fins considering thermal conductivity of the fin material is a function of the fin temperature. Former expression for fin effectiveness has been rearranged. The fin efficiency and the fin effectiveness have been obtained as a function of thermo-geometric fin parameter. The results have revealed that homotopy perturbation method is a very effective and practical approach for a rapid assessment of physical systems even if the energy balance equations include terms with strong nonlinearities. The resulting correlation equations can assist thermal design engineers for designing of straight fins with both constant and temperature-dependent thermal conductivity.

Effects of concavity level on heat loss, effectiveness and efficiency of a longitudinal fin exposed to natural convection and radiation

Purpose – The purpose of this paper is to investigate the effects of concavity level on performance parameters of a parabolic fin under the influences of natural convection and radiation. Design/methodology/approach – Computational fluid dynamics software (FLUENT) is used for the heat transfer analysis. Optimum fin geometry is searched in order to maximize the heat dissipation from fin to the ambient while minimizing the volume of fin. Findings – The fin profile with concavity level of 2 dissipates 14.92, 17.53, 24.33 and 26.60 percent more heat and uses 34.62, 49.64, 57.66 and 63.09 percent much material compared to the fin with concavity level of 4, 6, 8 and 10, respectively. It is also observed that the amount of heat dissipation per mass considerably increases with increasing concaveness. Research limitations/implications – The research was carried out for five different concavity levels in the range of 2-10. Practical implications – The results can be used in passive cooling applications of PV system...

Comments on “Analytical expression for electrical efficiency of PV/T hybrid air collector” by S. Dubey, G.S. Sandhu, and G.N. Tiwari

In this short communication, a theoretical attempt has been made and the analytical expression developed by Dubey, Sandhu, and Tiwari [2009. “Analytical Expression for Electrical Efficiency of PV/T Hybrid air Collector.” Applied Energy 86: 697–705.] for temperature-dependent electrical efficiency of air type PV/T collector has been corrected. The analyses have indicated that their efficiency expression only considers the effects of solar intensity. However, it is unequivocal from the governing equations that the ambient temperature is another variable that should be in the efficiency expression as an initial condition of the energy balance equation of flowing air. Although they asserted that the electrical efficiency of the system has been evaluated with respect to the variations in solar intensity and ambient temperature for a typical day in the month of April 2008 for New Delhi condition, the results clearly show that the ambient temperature has not been taken into account in their study. Their expression not including a term for ambient temperature proves our statement. In the present work, the corrected version of the efficiency expression is given.

Experimental and numerical investigation of a novel energy-efficient vacuum glazing technology for low-carbon buildings

In this study, a recently developed innovative window technology called vacuum tube window is introduced, and its performance assessment is presented through an experimental and numerical research. The novel design of vacuum tube window consists of evacuated tubes surrounded by Argon as inert gas to eliminate conductive and convective effects inside the window and thus to produce a building element with remarkably low overall heat transfer coefficient (U-value). Heat transfer inside the window was modelled via a reliable commercial computational fluid dynamics software ANSYS FLUENT. The accuracy of simulations was verified by environmental chamber tests. For the vacuum tube diameter of 28 mm, an excellent agreement between experimental and numerical data was achieved. For different values of design parameters such as pane thickness, tube thickness, tube diameter and Argon gap, total heat loss and U-value of the vacuum tube window and optimum data were evaluated. Optimum tube diameter was found to be 60 mm in terms of thermal performance characteristics, cost, lightness and aesthetic issues. It is concluded that the vacuum tube window is able to provide a U-value lower than 0.40 W/m2K, which is very promising for both retrofitting of existing buildings and new-build applications.

Energetic and exergetic performance assessment of solar cookers with different geometrical designs

In our previous paper, a thorough review of the available literature on solar cookers has been presented. In this paper, a thermodynamic performance assessment of solar cookers of different geometries has been carried out. In general, the study has aimed at providing a complete performance evaluation criterion for solar cookers irrespective of their geometrical design and also comparing the thermal performances of different types of solar cookers. Recent experimental studies considering conventional and novel geometrical constructions have been investigated in detail for data acquisition. Peak energy and exergy outputs, energetic and exergetic efficiencies, heat loss coefficients, cooker quality factors and portability factors have been obtained for each cooking design and the results have been analysed. Finally, some recommendations have been made to enhance the performance parameters of solar cookers.

An overview of domestic energy consumption in the UK: past, present and future

Global contribution from domestic sector towards energy use is quite remarkable, accounting for 20–40% of total primary energy consumption in developed countries. Current predictions indicate that the domestic energy consumption will steadily increase as a consequence of notable growth in world population, everlasting technological developments, growing demand for building services and rising comfort levels. In this respect, an accurate understanding and interpretation of energy consumption data in domestic sector is of vital importance for further amendments in energy policies at the global scale. Within the scope of this paper, an overview of the trends and some key drivers that have affected domestic energy consumption in the UK from 1970 to present is presented. Energy consumption by fuel type and end use, average domestic gas and electricity use in recent years, energy consumption per household and per person are illustrated in a comparable way.

Strategies for ideal indoor environments towards low/zero carbon buildings through a biomimetic approach

ABSTRACT Biomimicry is a relatively new discipline of applied science that seeks inspiration from natural systems for innovative solutions to human problems. Taking nature as ‘model, mentor and measure’ receives wide acceptance in the field of architecture but predominantly in conceptualising novel forms. The biomimicry concept is comprehensively analysed for its ability to provide more sustainable and possibly even regenerative built environments. As part of this study, first, various frameworks for approaching ‘biomimicry’ in general are discussed and then relevant examples pertaining to architecture are evaluated. Case studies are critiqued with respect to varied levels of sustainability achieved and its causative factors. In the second part, an approach model for ‘biomimetic architecture’ in the context of Mumbai is presented and applicable strategies based on climatic adaptation are suggested using local biodiversity as a library of organisms. The generic example of ‘human skin’ addressing the same adaptation is analysed and complemented by a state-of-the-art case study on similar lines. The results achieved clearly reveal that biomimicry is a successful approach to design and operate the sustainable built environments for the buildings of the future.