Solar Energy Harvesting Using Nanofluids-Based Concentrating Solar Collector

2012 ◽  
Vol 3 (3) ◽  
Author(s):  
Vikrant Khullar ◽  
Himanshu Tyagi ◽  
Patrick E. Phelan ◽  
Todd P. Otanicar ◽  
Harjit Singh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Collector ◽  
Incident Angle ◽  
Convective Heat Transfer Coefficient ◽  
Radiant Energy ◽  
Absorption Capacity ◽  
Solar Collectors ◽  
Solar Insolation ◽  
Solar Energy Harvesting ◽  
Efficient Heat Transfer

Dispersing trace amounts of nanoparticles into common base-fluids has a significant impact on the optical as well as thermophysical properties of the base-fluid. This characteristic can be utilized to effectively capture and transport solar radiation. Enhancement of the solar irradiance absorption capacity leads to a higher heat transfer rate resulting in more efficient heat transfer. This paper attempts to introduce the idea of harvesting solar radiant energy through usage of nanofluid-based concentrating parabolic solar collectors (NCPSC). In order to theoretically analyze the NCPSC, it has been mathematically modeled, and the governing equations have been numerically solved using finite difference technique. The results of the model were compared with the experimental results of conventional concentrating parabolic solar collectors under similar conditions. It was observed that while maintaining the same external conditions (such as ambient/inlet temperatures, wind speed, solar insolation, flow rate, concentration ratio, etc.) the NCPSC has about 5–10% higher efficiency as compared to the conventional parabolic solar collector. Furthermore, parametric studies were carried out to discover the influence of various parameters on performance and efficiency. The following parameters were studied in the present study: solar insolation, incident angle, and the convective heat transfer coefficient. The theoretical results clearly indicate that the NCPSC has the potential to harness solar radiant energy more efficiently than a conventional parabolic trough.

Solar Energy Harvesting Using Nanofluids-Based Concentrating Solar Collector

2012 ◽  
Author(s):  
Vikrant Khullar ◽  
Himanshu Tyagi ◽  
Patrick E. Phelan ◽  
Todd P. Otanicar ◽  
Harjit Singh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Collector ◽  
Base Fluid ◽  
Incident Angle ◽  
Convective Heat Transfer Coefficient ◽  
Radiant Energy ◽  
Absorption Capacity ◽  
Solar Collectors ◽  
Solar Insolation ◽  
Solar Energy Harvesting

Dispersing trace amounts of nanoparticles into the base-fluid has significant impact on the optical as well as thermo-physical properties of the base-fluid. This characteristic can be utilized in effectively capturing as well as transporting the solar radiant energy. Enhancement of the solar irradiance absorption capacity of the base fluid scales up the heat transfer rate resulting in higher & more efficient heat transfer. This paper attempts to introduce the idea of harvesting the solar radiant energy through usage of nanofluid-based concentrating parabolic solar collectors. In order to theoretically analyze the nanofluid-based concentrating parabolic solar collector (NCPSC) it has been mathematically modeled, and the governing equations have been numerically solved using finite difference technique. The results of the model were compared with the experimental results of conventional concentrating parabolic solar collectors under similar conditions. It was observed that while maintaining the same external conditions (such as ambient/inlet temperatures, wind speed, solar insolation, flow rate, concentration ratio etc.) the NCPSC has about 5–10% higher efficiency as compared to the conventional parabolic solar collector. Furthermore, some parametric studies were carried out which reflected the effect of various parameters such as solar insolation, incident angle, convective heat transfer coefficient etc. on the performance indicators such as thermal efficiency etc.

Comparison of Heat Transfer in Solar Collectors With Heat-Pipe Versus Flow-Through Absorbers

1987 ◽  
Vol 109 (4) ◽  
pp. 253-258 ◽  
Author(s):  
J. R. Hull
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Collector ◽  
Hot Water ◽  
Solar Collectors ◽  
Heat Transfer Characteristics ◽  
Absorption Chiller ◽  
Transfer Characteristics ◽  
Proper Design ◽  
Flow Through

Analysis of heat transfer in solar collectors with heat-pipe absorbers is compared to that for collectors with flow-through absorbers for systems that produce hot water or other heated fluids. In these applications the heat-pipe absorber suffers a heat transfer penalty compared with the flow-through absorber, but in many cases the penalty can be minimized by proper design at the heat-pipe condenser and system manifold. When the solar collector is used to drive an absorption chiller, the heat-pipe absorber has better heat transfer characteristics than the flow-through absorber.

Natural Convection in Collector Cavities With an Isoflux Absorber Plate

1983 ◽  
Vol 105 (1) ◽  
pp. 19-22 ◽  
Author(s):  
W. M. M. Schinkel ◽  
C. J. Hoogendoorn
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Natural Convection ◽  
Solar Collector ◽  
Numerical Study ◽  
Cold Wall ◽  
Solar Collectors ◽  
Absorber Plate ◽  
Hot Plate ◽  
Expected Values

The boundary condition at the hot absorber plate in a solar collector will influence the natural convection in the enclosure. For the isoflux boundary condition and an isothermal cold wall an experimental and numerical study has been made for Ra numbers from 105 to 107 and inclinations from 20 to 90 deg with the horizontal. For vertical enclosures the heat transfer by natural convection was about 19 percent above that for an isothermal hot plate. This decreases with angle of inclination, to 9 percent at 20 deg. For solar collectors it means that for cases where the absorber plate is not isothermal the convective losses can be about 10 percent above the usually expected values.

Applicability of Heat Mirrors in Reducing Thermal Losses in Concentrating Solar Collectors

2016 ◽  
Author(s):  
Prashant Mahendra ◽  
Vikrant Khullar ◽  
Madhup Mittal
Keyword(s):  
Heat Transfer ◽  
Thermal Efficiency ◽  
Solar Irradiance ◽  
Solar Collector ◽  
Flux Distribution ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Solar Collectors ◽  
Parabolic Trough ◽  
Glass Envelope

Flux distribution around the parabolic trough receiver being typically non-uniform, only a certain portion of the receiver circumference receives the concentrated solar irradiance. However, radiative and convective losses occur across the entire receiver circumference. This paper attempts to introduce the idea employing transparent heat mirror to effectively reduce the heat loss area and thus improve the thermal efficiency of the solar collector. Transparent heat mirror essentially has high transmissivity in the solar irradiance wavelength band and high reflectivity in the mid-infrared region thus it allows the solar irradiance to pass through but reflects the infrared radiation back to the solar selective metal tube. Practically, this could be realized if certain portion of the conventional low iron glass envelope is coated with Sn-In2O3 so that its acts as a heat mirror. In the present study, a parabolic receiver design employing the aforesaid concept has been proposed. Detailed heat transfer model has been formulated. The results of the model were compared with the experimental results of conventional concentrating parabolic trough solar collectors in the literature. It was observed that while maintaining the same external conditions (such as ambient/initial temperatures, wind speed, solar insolation, flow rate, concentration ratio etc.) the heat mirror-based parabolic trough concentrating solar collector has about 3–12% higher thermal efficiency as compared to the conventional parabolic solar collector. Furthermore, steady state heat transfer analysis reveals that depending on the solar flux distribution there is an optimum circumferential angle (θ = θoptimum, where θ is the heat mirror circumferential angle) up to which the glass envelope should be coated with Sn-In2O3. For angles higher than the optimum angle, the collector efficiency tends to decrease owing to increase in optical losses.

scholarly journals Performance Investigation of a Solar Thermal Collector Based on Nanostructured Energy Materials

2021 ◽  
Vol 7 ◽  
Author(s):  
Muhammad Zain ◽  
Muhammad Amjad ◽  
Muhammad Farooq ◽  
Zahid Anwar ◽  
Rabia Shoukat ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nanostructured Materials ◽  
Solar Collector ◽  
Conductive Heat Transfer ◽  
Outlet Temperature ◽  
Conductive Heat ◽  
Solar Collectors ◽  
Energy Materials ◽  
Working Fluids ◽  
Weather Model

The convective and conductive heat transfer between the solar collector and working fluids make photothermal performance limited, and result in a higher rate of heat loss from the surface of the conventional absorber to the surroundings. Direct absorption solar collectors (DASC) are a favorable alternative for their improved photothermal performance. In this study, a simulation based on the performance of a nanostructured solar collector has been carried out using TRNSYS. The connective and conductive heat transfer from direct solar collectors were improved by using nanofluids and three different nanostructured materials, CuO, GO, and ZnO, in this study. The analysis determines the outlet temperature of the working fluids that passed through the direct solar collector. The TRNSYS model consists of a direct solar collector and weather model for Lahore city, the simulations were performed for the whole year for 1,440 h. The stability of these nanostructured materials in the water was investigated by using a UV‐Vis spectrophotometer. Various performance parameters of direct solar collectors were determined, such as variation in outlet collector temperature and heat transfer rates. The numerical model is validated with experimental results. A maximum outlet temperature of 63°C was observed for GO-based nanofluids. The simulation results show that for the whole year, nanofluids improved the performance of direct solar collectors. Significant improvements in the heat transfer rate of 23.52, 21.11, and 15.09% were observed for the nanofluids based on nanostructures of CuO, ZnO, and GO respectively, as compared to water. These nanostructured energy materials are beneficial in solar-driven applications like solar desalination, solar water, and space heating.

scholarly journals Potential Use of Nanofluids in Solar Collectors: A Review

2020 ◽  
Vol 12 (01) ◽  
pp. 32-36
Author(s):  
Mangesh Gupta ◽  
Ram Bilas Prasad
Keyword(s):  
Heat Transfer ◽  
Solar Energy ◽  
Solar Collector ◽  
Solar Collectors ◽  
Review Of The Literature ◽  
Heat Transfer Medium ◽  
Potential Use

Solar energy is clean and easily available everywhere. It is trapped by a device called a solar collector. Solar collectors are used to utilize solar energy. Generally, the performances of the solar collector are low. Nanofluid is used in solar collectors to boost up the performance of the solar collector. This paper presents a review of the literature on the role of nanofluids in various types of solar collectors. It is found that the performance of the solar collector improves by using nanofluids as a heat transfer medium.

Wind Induced Heat Transfer Coefficient From Flat Horizontal Surfaces Exposed to Solar Radiation

2007 ◽  
Author(s):  
Subhash C. Mullick ◽  
Suresh Kumar ◽  
Basant K. Chourasia
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Loss ◽  
Convective Heat ◽  
Solar Collector ◽  
Convective Heat Transfer Coefficient ◽  
Loss Coefficient ◽  
Operating Conditions

Upward heat losses have strong effect on the performance of flat plate solar collectors under different operating conditions. Suitable equations for estimation of top heat loss coefficient have already been proposed [1,2]. The top heat loss coefficient is a function of wind induced convective heat transfer coefficient in a flat plate solar collector. It is, therefore, important to choose appropriate values of this convective heat transfer coefficient for correct estimation of the top heat loss coefficient. Researchers [3–6] have suggested different wind speed based correlations for estimation of the wind induced convective heat transfer coefficient. These correlations give different values of wind heat transfer coefficient thus resulting in variation in values of the top heat loss coefficient of a solar collector under same operating conditions. In present study, an attempt has been made to measure and study the wind induced convective heat transfer coefficient from exposed flat horizontal surfaces in real wind. For this purpose, three unglazed test plates of similar construction and different sizes were employed. Experiments were conducted on the three test plates over rooftop of a building in built environment. From experimental data of the test plate, of size 925mm × 865mm × 2mm, a correlation between wind heat transfer coefficient and wind speed has been obtained by linear regression. The obtained correlation has also been compared with work of other researchers [3–6]. Results obtained from experimental data of the three test plates provide some interesting information about wind induced convective heat transfer coefficient.

Heat Exchanger Theory Applied to the Design of Water- and Air-Heating Flat-Plate Solar Collectors

1988 ◽  
Vol 110 (2) ◽  
pp. 132-138 ◽  
Author(s):  
Gregory J. Kowalski ◽  
Arthur R. Foster
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Flat Plate ◽  
Solar Collector ◽  
Operating Conditions ◽  
Solar Collectors ◽  
Heat Transfer Characteristics ◽  
Air Heating ◽  
Collector Efficiency ◽  
The Difference

A general method for the design of flat-plate solar collectors based on solar collector theory has been developed. It can be applied to both liquid- and air-heating solar collectors. The solar collector efficiency is determined by the product of the effectiveness (ε) and the insolation use factor (IUF). The effectiveness describes the heat transfer characteristics of the collector and is shown to be a function of a solar number of transfer units (SNTU) and a parameter ψ. For an air-heating collector, the ψ parameter equals the collector efficiency factor, while for a liquid-heating collector it must account for the difference between the plate and tube heat transfer areas. The effectiveness and SNTU parameters are similar to the effectiveness and NTU parameters used in heat exchanger design methods. The IUF is a measure of the operating conditions of the collector. It represents the difference between the transmittance-absorptance product and the ratio of the minimum heat loss to the insolation on the exterior cover. The relationship between the effectiveness and the SNTU parameter is general for all nonconcentrating collectors. One advantage of this method over the traditional Hottel-Whillier method is that it separates the heat transfer characteristics of the solar collector from its optical properties and the operating conditions.

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