Optical Cascade Heat-Collection for Effective Solar Energy Gain

1987 ◽  
Vol 109 (4) ◽  
pp. 298-302 ◽  
Author(s):  
Isao Oshida ◽  
Akio Suzuki
Keyword(s):  
Solar Energy ◽  
Solar Collector ◽  
Fluid Flows ◽  
The Other ◽  
Heat Transfer Fluid ◽  
Cascade System ◽  
Medium Temperature ◽  
Fresnel Lenses ◽  
Higher Temperature ◽  
Tracking Device

Optical cascade heat collection of solar energy has proved effective for gaining thermal energy in the medium temperature region (80∼150° C). The cascade system consists of two separate absorbers (one hot and the other warm) and an optical system including CPC’s and Fresnel lenses which concentrate the direct solar radiation on one of the two absorbers. The temperature of the heat transfer fluid can be increased effectively if the fluid flows into the warm absorber first and then flows into the hot absorber. This type of solar collector, having no mechanical tracking device, can theoretically collect heat at a higher temperature than usual flat-plate collectors.

Solar Driven Absorption Chiller for Medium Temperature Food Refrigeration, a Study for Application in Indonesia

2014 ◽  
Vol 493 ◽  
pp. 167-172 ◽  
Author(s):  
I Nyoman Suamir
Keyword(s):  
Renewable Energy ◽  
Solar Energy ◽  
Weather Conditions ◽  
Heat Transfer Fluid ◽  
Cfd Modeling ◽  
Fluid Temperature ◽  
Renewable Energy Resources ◽  
Absorption Chiller ◽  
Total Energy Consumption ◽  
Medium Temperature

Indonesia has abundant renewable energy resources. In 2005 this country, however, only consumed 0.38% renewable energy of the total energy consumption. Most of the energy sources of the country are from fossil fuels which result in high CO2 emissions. Solar energy systems would be as an option to reduce the CO2 emissions of this country. This paper studied the application of solar energy to provide cooling for medium temperature food refrigeration based on Indonesian weather conditions. The paper additionally analyzed the environmental impact relating to CO2 emissions, and investigated the economical aspect. CFD-Fluent software was applied on modeling the modification of the absorption chiller generator to enable it to operate with heat from solar radiation, while F-Chart and Microsoft Excel spreadsheet were used to analyze the solar system and the economical viability of the technology. The results showed that the optimum modification of the absorption chiller was to use a jacket for heat addition. CFD modeling with Fluent using Diphyl THT as the heat transfer fluid (HTF) indicated that the system would function optimally at fluid temperature input of 180°C, whereas the optimum average temperature of the chiller generator would be 170 °C. The proposed technology was found economically less viable for food refrigeration compared to the vapor compression cycle using R-404A but it could provide a significant impact on the environment by a reduction of 37% CO2 emissions.

A Nonlinear Steady-State Characteristic Performance Curve for Medium-Temperature Solar Energy Collectors

1991 ◽  
Vol 113 (3) ◽  
pp. 164-171 ◽  
Author(s):  
P. C. Eames ◽  
B. Norton
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Solar Energy ◽  
Environmental Conditions ◽  
Solar Collector ◽  
Performance Curve ◽  
State Characteristic ◽  
Medium Temperature ◽  
New Approach ◽  
Made In

A numerical simulation model was employed to investigate the effects of ambient temperature and insolation of the efficiency of compound parabolic concentrating solar energy collectors. The limitations of presently used collector performance characterization curves were investigated and a new approach proposed. The major advantage of the new procedure over those employed previously is that different solar collector performance characteristics can now be readily normalized to a common set of environmental conditions. Thus, an equitable comparison may be made, in the context of the application conditions, of rating characteristics for disparate collectors which were obtained initially under different conditions.

scholarly journals Realization of a Based Concrete Thermal Storage Module used with a Medium Temperature Parabolic Trough Solar Collector

2015 ◽  
Vol 10 (1) ◽  
Keyword(s):  
Solar Energy ◽  
Solar Collector ◽  
Thermal Characteristic ◽  
Operation Time ◽  
Thermal Storage ◽  
Solar Irradiation ◽  
Parabolic Trough ◽  
Night Time ◽  
Medium Temperature ◽  
Parabolic Trough Solar Collector

Thermal solar energy has been considered for years as one of the most promising candidate for the substitution of the conventional systems providing a clean and sustainable energy solution. However, the intermittent aspect of the solar irradiation received by the earth surface presented a major obstacle for the exploitation and the integration of such technology in various applications. In order to avoid this barrier a thermal storage system for solar energy became a necessity especially for the concentrated solar power technologies. This paper shows the work carried out to determine the thermal behavior of a concrete storage unit for medium temperature applications. The experimental thermal storage module using concrete was realized and tested in order to be integrated in an advanced setup to a solar cooling installation powered by a parabolic trough solar collector. The thermal characteristic of the used concrete matrix was determined. The thermal storage module was tested under the same thermal conditions provided by the solar collectors. The temperature variations of the module during the charging and the heat loss during the night time were investigated. The test results showed some interesting thermal inertia of the concrete based storage module. The integration of the proposed storage module to the solar loop of the cooling installation will lead to extend the operation time after sunset and to decrease time lasted by the solar parabolic trough collector to reach the required operational temperature in the morning.

scholarly journals Pengaruh jumlah haluan pipa paralel pada kolektor surya plat datar absorber batu kerikil terhadap laju perpindahan panas

2016 ◽  
Vol 6 (2) ◽  
Author(s):  
M. Wirawan ◽  
R. Kurniawan ◽  
Mirmanto Mirmanto
Keyword(s):  
Renewable Energy ◽  
Solar Radiation ◽  
Solar Energy ◽  
Thermal Energy ◽  
Solar Collector ◽  
Alternative Energy ◽  
Mesh Size ◽  
The Other ◽  
Energy Crisis ◽  
Better Than

Recently the use of energy increases. It leads to the energy crisis. Therefore, it is important to promote alternative energy (renewable energy). One of renewable energies, which is potential in Indonesia, is solar enrgy. Solar energy can be harvested using a solar collector. This device can collect or absorb solar radiation and convert it to thermal energy. In this study, two identical collectors are used. One collector consists of 7 pipes and the other comprises 9 pipes. The overall dimension of the collector is 100 cm x 80 cm x 10 cm and the absorber of the collector is made of gravels with a mesh size of 9.5 -12.5 mm. The collectors are placed with a slope of 15o facing to North. The volumetric rates of water used in the experiments are 300 cc / min, 350 cc / min and 400 cc / min. The results show that the collector with 9 pipes is better than that with 7 pipes.

Effects of Double Glazing on the Performance of a Solar Thermal Collector

2014 ◽  
Vol 492 ◽  
pp. 118-122 ◽  
Author(s):  
Nabila Ihaddadène ◽  
Razika Ihaddadène ◽  
Azzeddine Mahdi
Keyword(s):  
Solar Energy ◽  
Solar Collector ◽  
The Other ◽  
Solar Thermal ◽  
Correct Position ◽  
Glass Pane ◽  
Solar Thermal Collector ◽  
Commercial Glass ◽  
To Come ◽  
Research Document

In this research document, an attempt has been made to come across the effect of double glazing on the efficiency of a solar thermal collector. Experiments were performed on an active solar energy demonstration system (ET 200). Commercial glass pane of 3 mm thick having the same dimensions as that of the apparatus was placed above the collector at a distance of 2 cm. Tests were done with and without the added glass. Experiments were performed for double glazing with two positions of the light meter. In one position, it was placed in the middle of the collector surface. While, in the other, the light meter was placed in the middle of the added glass. To study the effect of double glazing on the performance of the solar collector ET200, the correct position of the light meter was to place it exactly in the middle of the additional pane under the lamp. Double glazing decreased the efficiency of the collector of 15%.

Experimental Study of Single-Slope Solar Still Coupled With Nanofluid-Based Volumetric Absorption Solar Collector

2021 ◽  
Vol 144 (1) ◽  
Author(s):  
Jagteshwar Singh ◽  
M. K. Mittal ◽  
Vikrant Khullar
Keyword(s):  
Solar Energy ◽  
Solar Collector ◽  
Low Cost ◽  
Engine Oil ◽  
Heat Transfer Fluid ◽  
Working Fluid ◽  
Solar Still ◽  
Surface Absorption ◽  
Paraffin Oil ◽  
The Given

Abstract In the present endeavor, a conventional single-slope solar still has been modified to improve its performance by coupling it with a novel nanofluid-based volumetric absorption solar collector (NBVASC). A low-cost and thermally stable nanofluid (prepared by dispersing functionalized carbon soot nanoparticles extracted from used engine oil into paraffin oil) having high solar weighted absorptivity has been employed to volumetrically absorb the incident solar energy. This additional absorbed solar energy is provided to the solar still by circulating a heat transfer fluid in a closed loop through serpentine type heat exchangers placed inside the NBVASC and the solar still. The experiments were performed from May to July 2020, and the results of the experiments conducted on May 25 and June 9, 2020, are reported. Extensive on-sun experiments reveal that coupling NBVASC to the conventional still could lead to substantial performance enhancements—distillate productivity, thermal efficiency, and night distillate improved by 75.3%, 66.9%, and 33.9%, respectively. More importantly, solar still coupled to NBVASC was found to perform better at an optimum nanoparticle concentration of 1.25 mlL−1 (20.75% higher distillate productivity) than the solar still coupled to a surface absorption-based collector (with paraffin oil as the working fluid)—truly establishing the benefits of volumetric absorption over surface absorption under the given set of conditions. Overall, the present study represents a noteworthy step forward in realizing efficient solar energy-driven desalination systems for remote underdeveloped areas.

Experimental Comparison of Control Strategies for Solar Energy Systems Incorporating Dual Storage Tanks

1981 ◽  
Vol 103 (1) ◽  
pp. 47-51
Author(s):  
R. L. T. Wolfson ◽  
H. S. Harvey
Keyword(s):  
Solar Energy ◽  
Control Strategy ◽  
Solar Collector ◽  
Control Strategies ◽  
Energy Systems ◽  
The Other ◽  
Experimental Comparison ◽  
Storage Tanks ◽  
Period Data ◽  
And Control

Two identical solar collector systems were operated side by side for a 67 day period. Data acquisition and control of both systems were accomplished by a minicomputer. One system’s control strategy kept its two storage tanks at the same temperature, simulating a single tank. The other system employed a dual temperature strategy designed to allow greater flexibility in adjusting to varying isolation. The dual temperature strategy showed a modest 4 percent gain in energy delivered to a load.

scholarly journals Modification of a Solar Thermal Collector to Promote Heat Transfer inside an Evacuated Tube Solar Thermal Absorber

2021 ◽  
Vol 11 (9) ◽  
pp. 4100
Author(s):  
Rasa Supankanok ◽  
Sukanpirom Sriwong ◽  
Phisan Ponpo ◽  
Wei Wu ◽  
Walairat Chandra-ambhorn ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Small Scale ◽  
Medium Temperature ◽  
Change Behavior ◽  
Set Up ◽  
Evacuated Tube ◽  
Heating Medium

Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.

scholarly journals Amide-Type Substrates in the Synthesis of N-Protected 1-Aminomethylphosphonium Salts

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 552
Author(s):  
Dominika Kozicka ◽  
Paulina Zieleźny ◽  
Karol Erfurt ◽  
Jakub Adamek
Keyword(s):  
Reaction Times ◽  
The Other ◽  
Hydroxyl Group ◽  
Other Hand ◽  
Step Procedure ◽  
Higher Temperature ◽  
Short Time ◽  
Work Up

Herein we describe the development and optimization of a two-step procedure for the synthesis of N-protected 1-aminomethylphosphonium salts from imides, amides, carbamates, or lactams. Our “step-by-step” methodology involves the transformation of amide-type substrates to the corresponding hydroxymethyl derivatives, followed by the substitution of the hydroxyl group with a phosphonium moiety. The first step of the described synthesis was conducted based on well-known protocols for hydroxymethylation with formaldehyde or paraformaldehyde. In turn, the second (substitution) stage required optimization studies. In general, reactions of amide, carbamate, and lactam derivatives occurred at a temperature of 70 °C in a relatively short time (1 h). On the other hand, N-hydroxymethylimides reacted with triarylphosphonium salts at a much higher temperature (135 °C) and over longer reaction times (as much as 30 h). However, the proposed strategy is very efficient, especially when NaBr is used as a catalyst. Moreover, a simple work-up procedure involving only crystallization afforded good to excellent yields (up to 99%).

An example of steady laminar flow at large Reynolds number

1960 ◽  
Vol 9 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Iam Proudman
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Tangential Velocity ◽  
Fluid Flows ◽  
The Other ◽  
Large Reynolds Number ◽  
Rotational Flows ◽  
Flow Domain ◽  
Source Of Information

The purpose of this note is to describe a particular class of steady fluid flows, for which the techniques of classical hydrodynamics and boundary-layer theory determine uniquely the asymptotic flow for large Reynolds number for each of a continuously varied set of boundary conditions. The flows involve viscous layers in the interior of the flow domain, as well as boundary layers, and the investigation is unusual in that the position and structure of all the viscous layers are determined uniquely. The note is intended to be an illustration of the principles that lead to this determination, not a source of information of practical value.The flows take place in a two-dimensional channel with porous walls through which fluid is uniformly injected or extracted. When fluid is extracted through both walls there are boundary layers on both walls and the flow outside these layers is irrotational. When fluid is extracted through one wall and injected through the other, there is a boundary layer only on the former wall and the inviscid rotational flow outside this layer satisfies the no-slip condition on the other wall. When fluid is injected through both walls there are no boundary layers, but there is a viscous layer in the interior of the channel, across which the second derivative of the tangential velocity is discontinous, and the position of this layer is determined by the requirement that the inviscid rotational flows on either side of it must satisfy the no-slip conditions on the walls.

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